Refrigerating device
Abstract
Problem to be solved.To provide a refrigerating apparatus capable of suppressing time loss in a defrosting mode and quickly returning to a second mode.
Solution.It has a first compression unit 2c that uses a low-pressure refrigerant as an intermediate pressure refrigerant, a second compression unit 2d that uses an intermediate pressure refrigerant as a high-pressure refrigerant, a first mode, a second mode, and a defrosting mode. The control unit 9 is arranged below the first heat exchanger 40 and the first heat exchanger 40, which exchange heat between the high-pressure refrigerant and air in the first mode and exchange heat between the low-pressure refrigerant and air in the second mode. A second heat exchanger 60 is provided, which exchanges heat between the intermediate pressure refrigerant and air in the first mode, and exchanges heat between the low pressure refrigerant and air in the second mode. In the defrosting mode, the high-pressure refrigerant compressed by the second compression unit 2d flows to the first heat exchanger 40, the refrigerant that has passed through the first heat exchanger 40 flows to the second heat exchanger 60, and the second heat exchange occurs. It has a first refrigerant flow time zone in which a first refrigerant flow, in which the refrigerant that has passed through the vessel 60 is sucked into the first compression unit 2c, is generated. [Selection diagram] Fig. 1

Term
5 yearsto projected expiry
Projected expiry 7 October 2031, counted from filing; an application has no term until it is granted.
- Priority and filed
- Published
- Today
- Projected expiry
5 claims: 1 independent, 4 dependent
- 1低圧冷媒を圧縮して中間圧冷媒にする第1圧縮部(2c)と、 中間圧冷媒を圧縮して高圧冷媒にする第2圧縮部(2d)と、 第1モードと、第2モードと、を有し、前記第1圧縮部及び前記第2圧縮部を制御する制御部(9,90)と、 前記第1モードにおいて高圧冷媒と空気とを熱交換させ、前記第2モードにおいて低圧冷媒と空気とを熱交換させる第1熱交換器(40)と、 前記第1熱交換器の下方に配置され、前記第1モードにおいて中間圧冷媒と空気とを熱交換させ、前記第2モードにおいて低圧冷媒と空気とを熱交換させる第2熱交換器(60)と、を備え、 前記制御部は、前記第1熱交換器及び前記第2熱交換器に付着した霜を溶かす除霜モード、をさらに有し、 前記除霜モードは、 前記第2圧縮部で圧縮された高圧冷媒が前記第1熱交換器に流れ、前記第1熱交換器を通過した冷媒が前記第2熱交換器に流れ、前記第2熱交換器を通過した冷媒が前記第1圧縮部に吸入される第1冷媒流れ、が発生する第1冷媒流れ時間帯を有する、冷凍装置(1)。
- 2前記第2熱交換器は、複数あり、 前記第2熱交換器同士は、直列又は並列に接続されている、請求項1に記載の冷凍装置。
- 3前記第2モードにおいて高圧冷媒と空気又は水とを熱交換させる第3熱交換器(8,308)と、 前記第1モードにおいて、前記第1圧縮部の吐出側と前記第2熱交換器の一端とを接続する第1状態を採り、前記第2モードにおいて前記第1圧縮部の吐出側と前記第2圧縮部の吸入側とを接続する第2状態を採る第1切換機構(3)と、 前記第1モードにおいて、前記第2圧縮部の吐出側と前記第1熱交換器の一端とを接続する第3状態と、前記第2モードにおいて前記第2圧縮部の吐出側と前記第3熱交換器の一端とを接続する第4状態を採る第2切換機構(4)と、をさらに備え、 前記制御部は、前記除霜モードにおいて、前記第1切換機構を第2状態に制御し、前記第2切換機構を前記第3状態に制御する、請求項1又は2に記載の冷凍装置。
- 4前記除霜モードは、 前記第2圧縮部で圧縮された高圧冷媒が前記第1熱交換器に流れ、前記第1熱交換器を通過した冷媒が前記第3熱交換器に流れ、前記第3熱交換器を通過した冷媒が前記第1圧縮部に吸入される第2冷媒流れ、が発生する第2冷媒流れ時間帯を有しており、 前記第2冷媒流れ時間帯は、前記第1冷媒流れ時間帯の一部と重なる時間帯である、又は、前記第1冷媒流れ時間帯の前の時間帯である、請求項3に記載の冷凍装置。
- 5前記第1熱交換器と前記第3熱交換器とを接続する第1冷媒管(12)と、 前記第1冷媒管と前記第2熱交換器とを接続する第2冷媒管(13,113)と、 前記第1冷媒管に設けられる第1膨張機構(6,306)と、 前記第2冷媒管に設けられる第2膨張機構(14,314)と、をさらに備え、 前記制御部は、前記第1膨張機構及び前記第2膨張機構の開度を調節することによって、前記第1冷媒流れ及び/又は前記第2冷媒流れを発生させる、請求項4に記載の冷凍装置。
Independent claims5
133 paragraphs, as filed
The present invention relates to a refrigerating apparatus.
Conventionally, as disclosed in Patent Document 1 (Japanese Unexamined Patent Publication No. 2009-133581), a first compression unit that compresses a low-pressure refrigerant into an intermediate pressure refrigerant and a second compression unit that compresses an intermediate pressure refrigerant into a high-pressure refrigerant. A first heat exchanger that exchanges heat between the compression unit and the high-pressure refrigerant and air in the first mode (cooling mode) and heat exchange between the low-pressure refrigerant and air in the second mode (heating mode), and in the first mode. An air conditioner including a second heat exchanger that exchanges heat between the intermediate pressure refrigerant and air and exchanges heat between the low pressure refrigerant and air in the second mode has been proposed.
<p> In the air conditioner disclosed in Patent Document 1, in order to suppress frost formation in the first heat exchanger when the second mode is performed under the condition that the temperature of the air as the heat source of the first heat exchanger is low. It has a defrosting mode. In this air conditioner, basically, the refrigerant flow in the first mode is controlled in the defrosting mode. Here, for example, in the air conditioner disclosed in Patent Document 1, if the second heat exchanger is arranged below the first heat exchanger, it is discharged from the first compression unit in the defrosting mode. Since the intermediate pressure refrigerant first flows to the second heat exchanger, the frost adhering to the second heat exchanger arranged below melts before the frost adhering to the first heat exchanger. it is conceivable that. After that, the frost adhering to the first heat exchanger is melted by the high-pressure refrigerant discharged from the second compression section, but the drain water generated in the first heat exchanger is below the first heat exchanger. Since it will flow through the arranged second heat exchanger, it will not be possible to switch to the second mode while the drain water generated in the first heat exchanger flows through the second heat exchanger. That is, time is lost in the defrosting mode, and the return to the second mode is delayed.</p><p> Therefore, an object of the present invention is to provide a refrigerating apparatus capable of suppressing time loss in the defrosting mode and quickly returning to the second mode.</p>
<p> The refrigerating apparatus according to the first aspect of the present invention includes a first compression unit, a second compression unit, a control unit, a first heat exchanger, and a second heat exchanger. The first compression unit compresses the low-pressure refrigerant into an intermediate-pressure refrigerant. The second compression section compresses the intermediate pressure refrigerant into a high pressure refrigerant. The control unit has a first mode and a second mode, and controls the first compression unit and the second compression unit. The first heat exchanger exchanges heat between the high-pressure refrigerant and air in the first mode, and exchanges heat between the low-pressure refrigerant and air in the second mode. The second heat exchanger is arranged below the first heat exchanger and exchanges heat between the intermediate pressure refrigerant and air in the first mode and heat exchange between the low pressure refrigerant and air in the second mode. Further, the control unit further has a defrosting mode for melting the frost adhering to the first heat exchanger and the second heat exchanger. In the defrosting mode, the high-pressure refrigerant compressed in the second compression section flows to the first heat exchanger, the refrigerant that has passed through the first heat exchanger flows to the second heat exchanger, and passes through the second heat exchanger. It has a first refrigerant flow time zone in which a first refrigerant flow, in which the refrigerant is sucked into the first compression unit, is generated.</p><p> In the present invention, since the high-pressure refrigerant first flows to the first heat exchanger arranged above during the first refrigerant flow time zone, the surface of the first heat exchanger is more than the frost adhering to the surface of the second heat exchanger. The frost attached to the can be melted first. At this time, the molten water generated by melting the frost in the first heat exchanger flows to the second heat exchanger arranged below the first heat exchanger. Therefore, the frost adhering to the surface of the second heat exchanger can be easily melted. Next, since the refrigerant flowing through the first heat exchanger flows to the second heat exchanger, it adheres to the surface of the second heat exchanger and is easily dissolved by the molten water flowing from the first heat exchanger. The frost that is forming can be melted. Therefore, the time loss in the defrosting mode can be suppressed and the return to the second mode can be made quickly.</p><p> The refrigerating apparatus according to the second aspect of the present invention is the refrigerating apparatus according to the first aspect of the present invention, and there are a plurality of second heat exchangers, and the second heat exchangers are connected in series or in parallel. ing.</p><p> In the present invention, even when there are a plurality of second heat exchangers, the time loss in the defrosting mode can be suppressed and the return to the second mode can be made quickly.</p><p> The refrigerating apparatus according to the third aspect of the present invention is the refrigerating apparatus according to the first aspect or the second aspect of the present invention, and includes a third heat exchanger, a first switching mechanism, and a second switching mechanism. Further prepare. The third heat exchanger exchanges heat between the high-pressure refrigerant and air in the second mode. The first switching mechanism takes the first state of connecting the discharge side of the first compression unit and one end of the second heat exchanger in the first mode, and the discharge side of the first compression unit and the second in the second mode. Take the second state of connecting to the suction side of the compression unit. In the first mode, the second switching mechanism has a third state of connecting the discharge side of the second compression unit and one end of the first heat exchanger, and in the second mode, the discharge side of the second compression unit and the third heat. Take the fourth state of connecting to one end of the exchanger. Further, the control unit controls the first switching mechanism to the second state and the second switching mechanism to the third state in the defrosting mode.</p><p> In the present invention, by controlling the first switching mechanism as described above in the defrosting mode, the refrigerant discharged from the first compression unit flows to the second compression unit without going to the second heat exchanger. Then, the high-pressure refrigerant discharged from the second compression unit can flow to the first heat exchanger. Therefore, the frost attached to the first heat exchanger arranged above can be melted before the frost adhering to the second heat exchanger arranged below.</p><p> The refrigerating apparatus according to the fourth aspect of the present invention is the refrigerating apparatus according to the third aspect of the present invention, and the defrosting mode has a second refrigerant flow time zone. In the second refrigerant flow time zone, the high-pressure refrigerant compressed in the second compression section flows to the first heat exchanger, the refrigerant that has passed through the first heat exchanger flows to the third heat exchanger, and the third heat exchange occurs. This is the time zone during which the second refrigerant flow, in which the refrigerant that has passed through the vessel is sucked into the first compression section, occurs. The second refrigerant flow time zone is a time zone that overlaps with a part of the first refrigerant flow time zone, or is a time zone before the first refrigerant flow time zone.</p><p> In the present invention, the heat from the refrigerant flowing around the third heat exchanger including the third heat exchanger can be recovered by creating the second refrigerant flow time zone.</p><p> The refrigerating device according to the fifth aspect of the present invention is the refrigerating device according to the fourth aspect of the present invention, and includes a first refrigerant pipe, a second refrigerant pipe, a first expansion mechanism, and a second expansion mechanism. Further prepare. The first refrigerant pipe connects the first heat exchanger and the third heat exchanger. The second refrigerant pipe connects the first refrigerant pipe and the second heat exchanger. The first expansion mechanism is provided in the first refrigerant pipe. The second expansion mechanism is provided in the second refrigerant pipe. The control unit generates a first refrigerant flow and / or a second refrigerant flow by adjusting the opening degree of the first expansion mechanism and the second expansion mechanism.</p><p> In the present invention, the first refrigerant flow and / or the second refrigerant flow can be generated by controlling the first expansion mechanism and the second expansion mechanism. That is, the frost adhering to the first heat exchanger can be melted before the frost adhering to the second heat exchanger, and the refrigerant flowing around the third heat exchanger including the third heat exchanger. Can recover heat from.</p>
<p> In the refrigerating apparatus according to the first aspect of the present invention, it is possible to suppress the time loss in the defrosting mode and quickly return to the second mode.</p><p> In the refrigerating apparatus according to the second aspect of the present invention, even when there are a plurality of second heat exchangers, the time loss in the defrosting mode can be suppressed and the return to the second mode can be accelerated.</p><p> In the refrigerating apparatus according to the third aspect of the present invention, the refrigerant discharged from the first compression unit flows to the second compression unit without going to the second heat exchanger, and is discharged from the second compression unit. High pressure refrigerant can flow to the first heat exchanger.</p><p> In the refrigerating apparatus according to the fourth aspect of the present invention, heat from the refrigerant flowing around the third heat exchanger including the third heat exchanger can be recovered.</p><p> The refrigerating apparatus according to the fifth aspect of the present invention can melt the frost adhering to the first heat exchanger before the frost adhering to the second heat exchanger, and also includes the third heat exchanger. The heat from the refrigerant flowing around the third heat exchanger can be recovered.</p>
<figref num="1">The schematic block diagram of the air conditioner as an example of the refrigeration apparatus which concerns on this invention.</figref><figref num="2">The control block diagram of the control unit.</figref><figref num="3">Refrigerant pressure-enthalpy diagram illustrating refrigeration cycle during cooling operation in cooling mode.</figref><figref num="4">Refrigerant temperature-entropy diagram illustrating the refrigeration cycle during cooling operation in cooling mode.</figref><figref num="5">Refrigerant pressure-enthalpy diagram illustrating refrigeration cycle during heating operation in heating mode.</figref><figref num="6">Refrigerant temperature-entropy diagram illustrating refrigeration cycle during heating operation in heating mode.</figref><figref num="7">Schematic diagram of the heat exchange unit according to the modified example D.</figref><figref num="8">Schematic configuration diagram of an air conditioner as an example of the refrigerating device according to the modified example E</figref><figref num="9">The control block diagram of the control part which concerns on modification E.</figref><figref num="10">Refrigerant pressure-enthalpy diagram showing the refrigeration cycle during cooling operation in the cooling mode of the air conditioner according to the modified example E.</figref><figref num="11">Refrigerant pressure-enthalpy diagram illustrating the refrigeration cycle during heating operation in the heating mode of the air conditioner according to variant E.</figref>
Hereinafter, an embodiment of the air conditioner 1 as an example of the refrigerating device according to the present invention will be described with reference to the drawings.
(1) Configuration of air conditioner 1 FIG. 1 is a schematic configuration diagram of an air conditioner 1 as an example of the refrigerating device according to the present invention.
The air conditioner 1 includes a refrigerant circuit 10 configured to be able to switch between a cooling mode (corresponding to the first mode) in which the cooling operation is mainly performed and a heating mode (corresponding to the second mode) in which the heating operation is mainly performed. Have. Further, the air conditioner 1 is a device that performs a two-stage compression refrigeration cycle using a refrigerant (carbon dioxide in the present embodiment) that operates in a supercritical region.
The refrigerant circuit 10 of the air conditioner 1 mainly includes a compression mechanism 2, a first switching mechanism 3, a second switching mechanism 4, and a heat exchange unit 5 (first heat exchanger 40 and second heat exchanger 60). It has a first expansion mechanism 6, a third expansion mechanism 7, and a heat exchanger 8 on the user side. Hereinafter, the components of the refrigerant circuit 10 will be described.
(2) Components of refrigerant circuit 10 (2-1) Compression mechanism 2 The compression mechanism 2 has a first compression unit 2c and a second compression unit 2d, and the two compression units 2c and 2d compress the refrigerant in two stages. Since the first compression unit 2c and the second compression unit 2d have the same configuration, only the configuration of the first compression unit 2c will be described here, and the configuration of the second compression unit 2d will be described in the first. No. 22 is added instead of No. 21 indicating the configuration of the compression unit 2c, and the description is omitted. The first compression unit 2c has a closed structure in which a compression mechanism drive motor 21b, a drive shaft 21c, and a compression element 21d are housed in a casing 21a. The compression mechanism drive motor 21b is connected to the drive shaft 21c. The drive shaft 21c is connected to the compression element 21d. In the present embodiment, a multi-stage compression mechanism is configured by connecting a plurality of compression units 2c and 2d in which a single compression element 21d is incorporated in series. The first compression unit 2c is a positive displacement type compression unit such as a rotary type or a scroll type.
The compression mechanism 2 sucks the low-pressure refrigerant from the suction pipe 2a, compresses the sucked low-pressure refrigerant by the first compression unit 2c to make an intermediate-pressure refrigerant, and then discharges the low-pressure refrigerant into the intermediate refrigerant pipe 11 to the intermediate refrigerant pipe 11. The discharged intermediate pressure refrigerant is sucked into the second compression unit 2d, further compressed into a high pressure refrigerant, and then discharged to the discharge pipe 2b.
Here, in the intermediate refrigerant pipe 11, the intermediate pressure refrigerant compressed and discharged by the first compression unit 2c connected to the front stage side of the second compression unit 2d is connected to the rear stage side of the first compression unit 2c. It is a refrigerant pipe for sucking into the second compression unit 2d. The discharge pipe 2b is a refrigerant pipe for sending the high-pressure refrigerant discharged from the compression mechanism 2 (second compression unit 2d) to the first heat exchanger 40. The discharge pipe 2b is provided with a check valve 19 as a check valve that allows only the refrigerant flow from the second compression unit 2d to the second switching mechanism 4.
As described above, the compression mechanism 2 has two compression units 2c and 2d, and the low-pressure refrigerant is compressed by the first compression unit 2c on the front stage side of these compression units 2c and 2d to achieve an intermediate pressure. It is configured to be a refrigerant, and the intermediate pressure refrigerant is further compressed by the second compression unit 2d on the rear stage side to be a high pressure refrigerant.
(2-2) 1st switching mechanism 3 The first switching mechanism 3 is a mechanism for switching the flow direction of the refrigerant in the refrigerant circuit 10. The first switching mechanism 3 is a four-way switching valve connected to the suction side of the first compression unit 2c, the discharge side of the first compression unit 2c, the second heat exchanger 60, and the suction side of the second compression unit 2d. Is. The first switching mechanism 3 has the discharge side of the first compression unit 2c and the first in order to make the second heat exchanger 60 function as a radiator of the refrigerant compressed by the first compression unit 2c during the cooling operation in the cooling mode. 2 Take the first state of connecting to one end (upstream side) of the heat exchanger 60 (see the solid line of the first switching mechanism 3 in Fig. 1). On the other hand, the first switching mechanism 3 is discharged from the first compression unit 2c so that the second heat exchanger 60 does not function as a radiator of the refrigerant discharged from the first compression unit 2c during the heating operation in the heating mode. In order to suck the refrigerant into the second compression section 2d as it is, a second state is adopted in which the discharge side of the first compression section 2c and the suction side of the second compression section 2d are connected (in the first switching mechanism 3 of FIG. 1). See broken line). Further, the first switching mechanism 3 is in the second heat exchanger 60 in the second state in order to return the refrigerant evaporated in the second heat exchanger 60 to the first compression unit 2c during the heating operation in the heating mode. One end (downstream side) of is connected to the suction side of the first compression unit 2c.
The second switching mechanism 4 is not limited to the four-way switching valve, and is configured to have a function of switching the direction of the refrigerant flow as described above by, for example, combining a plurality of solenoid valves. It may be a thing.
As described above, in the cooling mode, the first switching mechanism 3 connects the discharge side of the first compression unit 2c and one end of the second heat exchanger 60 (that is, takes the first state), and in the heating mode. , Connect the discharge side of the first compression unit 2c and the suction side of the second compression unit 2d (that is, take the second state).
(2-3) 2nd switching mechanism 4 The second switching mechanism 4 is a mechanism for switching the flow direction of the refrigerant in the refrigerant circuit 10. The second switching mechanism 4 is connected to the suction side of the compression mechanism 2 (first compression unit 2c), the discharge side of the compression mechanism 2 (second compression unit 2d), the first heat exchanger 40, and the heat exchanger 8 on the user side. It is a four-way switching valve. The second switching mechanism 4 uses the first heat exchanger 40 as a radiator of the refrigerant compressed by the compression mechanism 2 (second compression unit 2d) and the user side heat exchanger 8 during the cooling operation in the cooling mode. In order to function as an evaporator of the cooled refrigerant in the first heat exchanger 40, the discharge side of the compression mechanism 2 (second compression unit 2d) and one end (upstream side) of the first heat exchanger 40 are connected. At the same time, a third state is taken in which the suction side of the compression mechanism 2 (first compression unit 2c) and one end (downstream side) of the heat exchanger 8 on the user side are connected (see the solid line of the second switching mechanism 4 in FIG. 1). ). On the other hand, the second switching mechanism 4 serves as a radiator for the refrigerant compressed by the compression mechanism 2 (second compression unit 2d) and the first heat exchanger 8 during the heating operation in the heating mode. In order to make 40 function as an evaporator of the cooled refrigerant in the utilization side heat exchanger 8, the discharge side of the compression mechanism 2 (second compression unit 2d) and the other end (upstream side) of the utilization side heat exchanger 8 And take the fourth state of connecting the suction side of the compression mechanism 2 (first compression unit 2c) and the other end (downstream side) of the first heat exchanger 40 (of the second switching mechanism 4 in FIG. 1). (See dashed line) is possible. The second switching mechanism 4 is not limited to the four-way switching valve, and is configured to have a function of switching the direction of the refrigerant flow as described above by, for example, combining a plurality of solenoid valves. It may be a thing.
(2-4) Heat exchange unit 5 The heat exchange unit 5 has a plurality of heat exchangers (in this embodiment, the first heat exchanger 40 and the second heat exchanger 60), and is between the refrigerant flowing inside and the passing air passing outside. By exchanging heat, it functions as a radiator or evaporator of the refrigerant. The first heat exchanger 40 and the second heat exchanger 60 have a two-stage structure in which the first heat exchanger 40 is arranged in the upper stage and the second heat exchanger 60 is arranged in the lower stage, and are integrated. ing. Hereinafter, the first heat exchanger 40 and the second heat exchanger 60 will be described. The air passing outside the first heat exchanger 40 and the second heat exchanger 60 is supplied by the fan 50. The fan 50 is driven by the fan drive motor 50a.
(2-4-1) First heat exchanger 40 The first heat exchanger 40 mainly includes a pair of headers extending in the vertical direction separated from each other and a pair of headers extending horizontally so as to intersect (substantially orthogonal to) the extending direction of the headers. A laminated microchannel heat exchanger composed of a plurality of flat tubes arranged in a vertical direction and heat transfer fins arranged between the flat tubes is used. One end of the first heat exchanger 40 is connected to the second switching mechanism 4, and the other end is connected to the first expansion mechanism 6. The first heat exchanger 40 functions as a radiator of the high-pressure refrigerant compressed by the compression mechanism 2 (second compression unit 2d) during the cooling operation in the cooling mode, and the compression mechanism 2 (second) during the heating operation in the heating mode. It functions as an evaporator of the refrigerant compressed by the compression unit 2d).
As described above, the first heat exchanger 40 exchanges heat between the high-pressure refrigerant compressed by the second compression unit 2d and the air as a cooling source during the cooling operation in the cooling mode, and during the heating operation in the heating mode. In, the low-pressure refrigerant decompressed by the first expansion mechanism 6 is configured to exchange heat with air as a heating source.
(2-4-2) Second heat exchanger 60 The second heat exchanger 60 is arranged below the first heat exchanger 40, and is located between the first compression unit 2c (specifically, the first switching mechanism 3) and the second compression unit 2d. It is provided in. Similar to the first heat exchanger 40, the second heat exchanger 60 mainly has a pair of headers extending in the vertical direction separated from each other and a pair of headers intersecting each other with respect to the extending direction of the headers (omitted). A laminated microchannel heat exchanger consisting of a plurality of flat tubes extending in the horizontal direction so as to be orthogonal to each other and arranged in the vertical direction (vertical direction), and heat transfer fins arranged between the flat tubes. It is used. The second heat exchanger 60 is configured such that one end thereof is connected to the first switching mechanism 3 and the other end is connected to the second compression unit 2d. During the cooling operation in the cooling mode, the second heat exchanger 60 is compressed by the first compression unit 2c on the front stage side and sucked into the second compression unit 2d on the rear stage side in order to improve the performance during the cooling operation. , Acts as a radiator for intermediate pressure refrigerant in the refrigeration cycle. On the other hand, during the heating operation in the heating mode, in order to improve the performance during the heating operation, the refrigerant compressed by the second compression unit 2d together with the first heat exchanger 40 (specifically, the user side heat exchanger 8). Acts as an evaporator of the refrigerant cooled by).
As described above, the second heat exchanger 60 exchanges heat between the intermediate pressure refrigerant compressed by the first compression unit 2c and the air as a cooling source during the cooling operation in the cooling mode, and the heating operation in the heating mode. At times, it is configured to exchange heat between the low-pressure refrigerant cooled by the user-side heat exchanger 8 and decompressed by the first expansion mechanism 6 and the air as a heating source.
In the present embodiment, the intermediate refrigerant pipe 11 includes a first intermediate refrigerant pipe 11a that connects the discharge side of the first compression unit 2c and the first switching mechanism 3, the first switching mechanism 3 and the second heat exchanger. The second intermediate refrigerant pipe 11b that connects one end of 60, the third intermediate refrigerant pipe 11c that connects the other end of the second heat exchanger 60 and the suction side of the second compression unit 2d, and the first compression unit 2c. It has a fourth intermediate refrigerant pipe 11d that connects the suction side (specifically, the first switching mechanism 3) and the suction side of the second compression unit 2d. The first intermediate refrigerant pipe 11a is provided with a check valve 17 as a check valve that allows only the refrigerant flow from the first compression unit 2c to the first switching mechanism 3. The fourth intermediate refrigerant pipe 11d has a check valve 18 as a check valve that allows only the refrigerant flow from the discharge side (first switching mechanism 3) of the first compression unit 2c to the suction side of the second compression unit 2d. Is provided.
Further, in the present embodiment, in order to make the second heat exchanger 60 function as a refrigerant evaporator during the heating operation, a second heat exchange is performed on the upstream side of the refrigerant flow during the heating operation of the first heat exchanger 40. A vessel guide tube 13 is provided. Specifically, the second heat exchanger guide pipe 13 branches a part of the refrigerant flowing between the user side heat exchanger 8 and the first expansion mechanism 6 during the heating operation and the defrosting operation. , A refrigerant pipe that can flow through the second heat exchanger 60 (specifically, the third intermediate refrigerant pipe 11c), and is used with the first expansion mechanism 6 of the refrigerant pipe 12 (corresponding to the first refrigerant pipe). It is configured to connect the portion between the side heat exchanger 8 and the second heat exchanger 60 (specifically, the third intermediate refrigerant pipe 11c). Here, the refrigerant pipe 12 is a refrigerant pipe that connects the first heat exchanger 40 and the user-side heat exchanger 8. The second heat exchanger guide pipe 13 is provided with a second expansion mechanism 14 for reducing the pressure of the refrigerant. The second expansion mechanism 14 is an electric expansion valve whose opening degree can be adjusted. The second expansion mechanism 14 reaches the low pressure in the refrigeration cycle before sending the refrigerant sent from the user side heat exchanger 8 and flowing through the second heat exchanger guide pipe 13 to the second heat exchanger 60 during the heating operation. Reduce the pressure.
(2-5) 1st expansion mechanism 6 The first expansion mechanism 6 is a mechanism for reducing the pressure of the refrigerant, and an electric expansion valve capable of adjusting the opening degree is used. The first expansion mechanism 6 is provided in the refrigerant pipe 12 that connects the first heat exchanger 40 and the user-side heat exchanger 8. One end of the first expansion mechanism 6 is connected to the first heat exchanger 40, and the other end is connected to the third expansion mechanism 7.
(2-6) Third expansion mechanism 7 The third expansion mechanism 7 is a mechanism for reducing the pressure of the refrigerant, and an electric expansion valve capable of adjusting the opening degree is used. The third expansion mechanism 7 is provided in the refrigerant pipe 12. One end of the third expansion mechanism 7 is connected to the first expansion mechanism 6, and the other end is connected to the user side heat exchanger 8.
(2-7) User side heat exchanger 8 (equivalent to the third heat exchanger) The user-side heat exchanger 8 is a heat exchanger that functions as a refrigerant evaporator or a radiator. The user-side heat exchanger 8 is configured such that one end is connected to the third expansion mechanism 7 and the other end is connected to the second switching mechanism 4. The user-side heat exchanger 8 serves as an evaporator of the refrigerant cooled by the first heat exchanger 40 during the cooling operation in the cooling mode, and the compression mechanism 2 (specifically, the second compression) during the heating operation in the heating mode. It functions as a radiator of the refrigerant compressed in part 2d). Although not shown here, the user-side heat exchanger 8 is supplied with water or air as a heat source or a cooling source that exchanges heat with the refrigerant flowing through the user-side heat exchanger 8. ..
(3) Control unit 9 FIG. 2 is a control block diagram of the control unit 9.
The air conditioner 1 includes a compression mechanism drive motor 21b, a first switching mechanism 3, a second switching mechanism 4, a first expansion mechanism 6, a second expansion mechanism 14, and a fan drive of the first compression unit 2c and the second compression unit 2d. It has a control unit 9 that controls the operation of each unit that constitutes the air conditioner 1 such as the motor 50a.
The control unit 9 is connected to various sensors provided in the air conditioner 1. The various sensors include a first heat exchange temperature sensor 51, a second heat exchange outlet temperature sensor 52, an air temperature sensor 53, and the like. The first heat exchange temperature sensor 51 is provided in the first heat exchanger 40 and is a sensor that detects the temperature of the refrigerant flowing through the first heat exchanger 40. The second heat exchange outlet temperature sensor 52 is provided at the outlet of the second heat exchanger 60, and is a sensor that detects the temperature of the refrigerant at the outlet of the second heat exchanger 60. The air temperature sensor 53 is provided in the main body of the air conditioner 1 and is a sensor that detects the temperature of air as a heat source of the first heat exchanger 40 and the second heat exchanger 60.
As described above, the control unit 9 has a cooling mode, a heating mode, and a defrosting mode, and switches between these modes according to detection signals from various sensors.
When the heating operation in the heating mode is performed under the condition that the temperature of the air as the heat source of the first heat exchanger and the second heat exchanger is low, the first heat exchanger and the second heat function as the evaporator of the refrigerant. Frost or ice may adhere to the surface of the exchanger. Therefore, in the air conditioner 1, the control unit 9 has a defrosting mode. Simply put, the defrosting mode is a mode in which frost and ice adhering to the first heat exchanger 40 and the second heat exchanger 60 are melted to defrost / deicer.
(4) Operation of air conditioner 1 FIG. 3 is a refrigerant pressure-enthalpy diagram illustrating a refrigeration cycle during cooling operation in cooling mode. FIG. 4 is a refrigerant temperature-entropy diagram showing the refrigeration cycle during the cooling operation in the cooling mode. FIG. 5 is a refrigerant pressure-enthalpy diagram illustrating the refrigeration cycle during heating operation in heating mode. FIG. 6 is a refrigerant temperature-entropy diagram illustrating the refrigeration cycle during heating operation in heating mode.
Hereinafter, the operation of the air conditioner 1 will be described with reference to FIGS. 1 and 3 to 6. The operation control in the following cooling operation, heating operation, first defrosting operation, and second defrosting operation is performed by the above-mentioned control unit 9. Further, in the following description, "high pressure" means high pressure in the refrigeration cycle (that is, pressure at points D and E in FIGS. 3 and 4 and pressure at points D and F in FIGS. 5 and 6). , "Low pressure" means low pressure in the refrigeration cycle (ie, pressure at points A, F in FIGS. 3 and 4, pressure at points A, E, G in FIGS. 5 and 6), "intermediate pressure". Means the intermediate pressure in the refrigeration cycle (that is, the pressure at points B and C in FIGS. 3 to 6).
As described above, the operation mode of the air conditioner 1 includes a cooling mode, a heating mode, and a defrosting mode. Hereinafter, operation control in various modes will be described.
(4-1) Cooling mode In the cooling mode, the cooling operation is mainly performed. During the cooling operation, the first switching mechanism 3 takes the first state and the second switching mechanism 4 takes the third state. The first expansion mechanism 6 is controlled to be in a fully open state. The opening degree of the third expansion mechanism 7 is adjusted. The second expansion mechanism 14 is controlled to be in the closed state.
When the compression mechanism 2 is driven in the state of the refrigerant circuit 10, the low-pressure refrigerant (see points A in FIGS. 1, 3 and 4) first starts from the suction pipe 2a and first in the first compression section 2c on the front stage side. , After being compressed to the intermediate pressure by the first compression unit 2c, it is discharged to the intermediate refrigerant pipe 11 (specifically, the first intermediate refrigerant pipe 11a) (points of FIGS. 1, 3 and 4). See B). The intermediate pressure refrigerant discharged from the first compression unit 2c is sent to the second heat exchanger 60 via the first switching mechanism 3 and the second intermediate refrigerant pipe 11b. The intermediate pressure refrigerant sent to the second heat exchanger 60 is radiated and cooled by exchanging heat with the air as a cooling source passing outside in the second heat exchanger 60 (Fig. 1, Fig. 1,). See point C in Figures 3 and 4). The refrigerant radiated and cooled in the second heat exchanger 60 is sucked into the second compression unit 2d connected to the rear stage side of the first compression unit 2c via the third intermediate refrigerant pipe 11c. The refrigerant sucked into the second compression section 2d is compressed by the second compression section 2d to become a high-pressure refrigerant, which is discharged to the discharge pipe 2b (see points D in FIGS. 1, 3 and 4). Here, the high-pressure refrigerant discharged from the second compression unit 2d is the compression unit 2c, By the two-stage compression operation by 2d, the pressure is compressed to exceed the critical pressure (that is, the critical pressure Pcp at the critical point CP shown in FIG. 3). The high-pressure refrigerant discharged from the second compression unit 2d is sent to the first heat exchanger 40, which functions as a radiator of the refrigerant, through the second switching mechanism 4. Then, the high-pressure refrigerant sent to the first heat exchanger 40 exchanges heat with the air as a cooling source passing outside in the first heat exchanger 40, dissipates heat, and is cooled (FIG. 1, FIG. 1, See point E in Figures 3 and 4). The high-pressure refrigerant radiated and cooled in the first heat exchanger 40 is sent to the third expansion mechanism 7 via the refrigerant pipe 12 and the first expansion mechanism 6. The high-pressure refrigerant sent to the third expansion mechanism 7 is decompressed by the third expansion mechanism 7 to become a low-pressure gas-liquid two-phase state refrigerant, and is sent to the utilization side heat exchanger 8 that functions as a refrigerant evaporator. (See point F in Figures 1, 3 and 4). The low-pressure gas-liquid two-phase refrigerant sent to the user-side heat exchanger 8 exchanges heat with water or air as a heating source to be heated and evaporates (FIGS. 1, 3 and). See point A in Figure 4). The low-pressure refrigerant evaporated in the user-side heat exchanger 8 is sucked into the first compression unit 2c again via the second switching mechanism 4 and the suction pipe 2a.
In the cooling mode of the air conditioner 1, the cooling operation is performed as described above.
(4-2) Heating mode In the heating mode, the heating operation is mainly performed. During the heating operation, the first switching mechanism 3 takes the second state, and the second switching mechanism 4 takes the fourth state. The third expansion mechanism 7 is controlled to be in the fully open state. The opening degree of the first expansion mechanism 6 and the second expansion mechanism 14 is adjusted. During the heating operation, the second heat exchanger 60 does not function as a radiator of the refrigerant compressed by the first compression unit 2c, and together with the first heat exchanger 40, the refrigerant compressed by the second compression unit 2d. (Specifically, it functions as an evaporator of the refrigerant cooled by the heat exchanger 8 on the user side).
When the compression mechanism 2 is driven in the state of the refrigerant circuit 10, the low-pressure refrigerant (see points A in FIGS. 1, 5 and 6) first starts from the suction pipe 2a and first in the first compression section 2c on the front stage side. , After being compressed to the intermediate pressure by the first compression unit 2c, it is discharged to the first intermediate refrigerant pipe 11a of the intermediate refrigerant pipe 11 (see point B in FIGS. 1, 5 and 6). The intermediate pressure refrigerant discharged to the first intermediate refrigerant pipe 11a passes through a part of the fourth intermediate refrigerant pipe 11d and the third intermediate refrigerant pipe 11c without passing through the second heat exchanger 60 (FIGS. 1, FIG. 5 and point C in FIG. 6), it is sucked into the second compression section 2d connected to the rear side of the first compression section 2c. The refrigerant sucked into the second compression section 2d is compressed by the second compression section 2d to become a high-pressure refrigerant, which is discharged to the discharge pipe 2b (see points D in FIGS. 1, 5 and 6). Here, the high-pressure refrigerant discharged from the second compression unit 2d is the compression unit 2c, as in the cooling operation. By the two-stage compression operation by 2d, the pressure is compressed to exceed the critical pressure (that is, the critical pressure Pcp at the critical point CP shown in FIG. 5). The high-pressure refrigerant discharged from the second compression unit 2d is sent to the utilization side heat exchanger 8 which functions as a radiator of the refrigerant through the second switching mechanism 4. The high-pressure refrigerant sent to the user-side heat exchanger 8 exchanges heat with water or air as a cooling source in the user-side heat exchanger 8 to dissipate heat and cool (FIGS. 1, 5, and 5). See point F at 6). A part of the high-pressure refrigerant cooled in the user-side heat exchanger 8 is sent to the first expansion mechanism 6 via the third expansion mechanism 7, and the rest is sent to the second heat exchanger guide pipe 13. It is sent to the second expansion mechanism 14 via. The high-pressure refrigerant sent to the first expansion mechanism 6 is decompressed by the first expansion mechanism 6 to become a low-pressure gas-liquid two-phase state refrigerant (see points E in FIGS. 1, 5 and 6). On the other hand, the refrigerant sent to the second expansion mechanism 14 is decompressed by the second expansion mechanism 14 to become a low-pressure gas-liquid two-phase state refrigerant (see point G in FIGS. 1, 5 and 6). The low-pressure gas-liquid two-phase state refrigerant decompressed by the first expansion mechanism 6 is sent to the first heat exchanger 40 that functions as an evaporator of the refrigerant, while the low-pressure low pressure decompressed by the second expansion mechanism 14 The gas-liquid two-phase state refrigerant is sent to the second heat exchanger 60, which functions as a refrigerant evaporator. The low-pressure gas-liquid two-phase refrigerant sent to the first heat exchanger 40 exchanges heat with air as a heating source to be heated and evaporates (point A in FIGS. 1, 5 and 6). reference). On the other hand, the low-pressure gas-liquid two-phase refrigerant sent to the second heat exchanger 60 is also heated and evaporated by exchanging heat with air as a heating source, similarly to the first heat exchanger 40 (similar to the first heat exchanger 40). See point A in Figures 1, 5 and 6). Then, the low-pressure refrigerant evaporated in the first heat exchanger 40 is sucked into the first compression unit 2c again via the second switching mechanism 4 and the suction pipe 2a, and is evaporated in the second heat exchanger 60. The low-pressure refrigerant generated is sucked into the first compression unit 2c again through the first switching mechanism 3 and the suction pipe 2a. The refrigerant is sent to the second heat exchanger 60, which functions as a refrigerant evaporator. The low-pressure gas-liquid two-phase refrigerant sent to the first heat exchanger 40 exchanges heat with air as a heating source to be heated and evaporates (point A in FIGS. 1, 5 and 6). reference). On the other hand, the low-pressure gas-liquid two-phase refrigerant sent to the second heat exchanger 60 is also heated and evaporated by exchanging heat with air as a heating source, similarly to the first heat exchanger 40 (similar to the first heat exchanger 40). See point A in Figures 1, 5 and 6). Then, the low-pressure refrigerant evaporated in the first heat exchanger 40 is sucked into the first compression unit 2c again via the second switching mechanism 4 and the suction pipe 2a, and is evaporated in the second heat exchanger 60. The low-pressure refrigerant generated is sucked into the first compression unit 2c again through the first switching mechanism 3 and the suction pipe 2a. The refrigerant is sent to the second heat exchanger 60, which functions as a refrigerant evaporator. The low-pressure gas-liquid two-phase refrigerant sent to the first heat exchanger 40 exchanges heat with air as a heating source to be heated and evaporates (point A in FIGS. 1, 5 and 6). reference). On the other hand, the low-pressure gas-liquid two-phase refrigerant sent to the second heat exchanger 60 is also heated and evaporated by exchanging heat with air as a heating source, similarly to the first heat exchanger 40 (similar to the first heat exchanger 40). See point A in Figures 1, 5 and 6). Then, the low-pressure refrigerant evaporated in the first heat exchanger 40 is sucked into the first compression unit 2c again via the second switching mechanism 4 and the suction pipe 2a, and is evaporated in the second heat exchanger 60. The low-pressure refrigerant generated is sucked into the first compression unit 2c again through the first switching mechanism 3 and the suction pipe 2a.
In the heating mode of the air conditioner 1, the heating operation is performed as described above.
(4-3) Defrost mode Switching from the heating mode to the defrosting mode is performed when it is determined that frost has formed on the first heat exchanger 40 and the second heat exchanger 60. Whether or not frost is formed on the first heat exchanger 40 and the second heat exchanger 60 is determined by determining the temperature of the refrigerant flowing in the first heat exchanger 40 detected by the first heat exchange temperature sensor 51. , It is performed based on the temperature of the refrigerant at the outlet of the second heat exchanger 60 detected by the second heat exchange outlet temperature sensor 52. Specifically, when it is detected that these temperatures are below a predetermined temperature corresponding to the conditions under which frost is formed on the first heat exchanger 40 and the second heat exchanger 60, the first heat exchanger 40 and It is determined that frost has formed on the second heat exchanger 60. Since the predetermined temperature depends on the temperature of air as a heat source, it is preferable to set the predetermined temperature as a function of the temperature of air detected by the air temperature sensor 53. If a temperature sensor is provided at the inlet or outlet of the first heat exchanger 40 and at the inlet or inside of the second heat exchanger 60, the first heat exchange temperature sensor 51 and the second heat exchange outlet are provided. Instead of the temperature of the refrigerant detected by the temperature sensor 52, the temperature of the refrigerant detected by these temperature sensors may be used for determining the temperature condition.
On the other hand, in the defrosting mode, when it is determined that the first heat exchanger 40 and the second heat exchanger 60 are not frosted, the mode is switched to the heating mode. Specifically, the temperature of the refrigerant flowing in the first heat exchanger 40 detected by the first heat exchange temperature sensor 51 and the outlet of the second heat exchanger 60 detected by the second heat exchange outlet temperature sensor 52. When it is detected that the temperature of the refrigerant exceeds the above-mentioned predetermined temperature, it is determined that frost has not occurred in the first heat exchanger 40 and the second heat exchanger 60.
Various operations in the defrost mode will be described below. In the defrosting mode, the first defrosting operation and the second defrosting operation are mainly performed. Specifically, after the first defrosting operation is performed, the second defrosting operation is performed.
(4-3-1) 1st defrosting operation In the first defrosting operation, the first switching mechanism 3 is controlled to the second state, and the second switching mechanism 4 is controlled to the third state. The first expansion mechanism 6 is controlled to the fully open state. The second expansion mechanism 14 is controlled to be in the closed state. The opening degree of the third expansion mechanism 7 is adjusted. It also controls the fan drive motor 50a to a stopped state. If the heat source of the refrigerant flowing through the user-side heat exchanger 8 is air, the fan drive motor (not shown) of the fan that generates the air flow supplied to the user-side heat exchanger 8 is also controlled to be stopped. ..
The flow of the refrigerant at this time will be described below.
First, the low-pressure refrigerant sucked from the suction pipe 2a into the first compression section 2c is compressed by the first compression section 2c to become an intermediate-pressure refrigerant, and is discharged to the first intermediate refrigerant pipe 11a of the intermediate refrigerant pipe 11. .. The intermediate pressure refrigerant discharged to the first intermediate refrigerant pipe 11a is sucked into the second compression unit 2d via the first switching mechanism 3, the fourth intermediate refrigerant pipe 11d, and the third intermediate refrigerant pipe 11c. It is further compressed to become a high-pressure refrigerant, which is discharged to the discharge pipe 2b. Here, the refrigerant discharged from the compression mechanism 2 (second compression unit 2d) is compressed to a pressure exceeding the critical pressure of the refrigerant by the two-stage compression operation by the compression units 2c and 2d. The high-pressure refrigerant discharged to the discharge pipe 2b is sent to the first heat exchanger 40 through the second switching mechanism 4. When the refrigerant sent to the first heat exchanger 40 passes through the first heat exchanger 40, it exchanges heat with frost and ice adhering to the first heat exchanger 40 to dissipate heat and dissipate heat to a high-pressure liquid refrigerant. At the same time, it melts frost and ice. The high-pressure refrigerant that has passed through the first heat exchanger 40 is sent to the third expansion mechanism 7 via the refrigerant pipe 12 and the first expansion mechanism 6. The high-pressure refrigerant sent to the third expansion mechanism 7 is decompressed by the third expansion mechanism 7 to become a low-pressure refrigerant. The low-pressure refrigerant decompressed by the third expansion mechanism 7 is sent to the user-side heat exchanger 8. The refrigerant sent to the user-side heat exchanger 8 is evaporated in the user-side heat exchanger 8 to become a low-pressure gas refrigerant. Then, the refrigerant evaporated by the user-side heat exchanger 8 is sucked into the first compression unit 2c again via the second switching mechanism 4 and the suction pipe 2a. Although it has been described here that the first expansion mechanism 6 is controlled to the fully open state, the opening degree may be adjusted. In this case, the high-pressure refrigerant that has passed through the first heat exchanger 40 may be depressurized to an intermediate pressure in the first expansion mechanism 6 and further depressurized to a low pressure in the third expansion mechanism 7.
As described above, in the first defrosting operation, the high-pressure refrigerant compressed by the second compression unit 2d flows to the first heat exchanger 40, and the refrigerant that has passed through the first heat exchanger 40 exchanges heat on the user side. There is a refrigerant flow (corresponding to the second refrigerant flow) that flows into the vessel 8 and the refrigerant that has passed through the heat exchanger 8 on the user side is sucked into the first compression unit 2c. Here, the high-temperature and high-pressure refrigerant discharged from the second compression unit 2d is flowed through the first heat exchanger 40 to melt the frost and ice adhering to the first heat exchanger 40 and defrost / de-ice. Further, by forming a refrigerant flow such that the refrigerant compressed by the second compression unit 2d passes through the utilization side heat exchanger 8, the utilization side heat exchanger 8 including the utilization side heat exchanger 8 can be formed. The heat from the refrigerant flowing around the can be recovered.
(4-3-2) Second defrosting operation The switching from the first defrosting operation to the second defrosting operation is triggered when the defrosting of the first heat exchanger 40 is almost completed. Specifically, the defrosting of the first heat exchanger 40 is considered to be almost completed, or the predetermined temperature of the refrigerant flowing in the first heat exchanger 40 is set in advance, and the first defrosting is performed. From the first defrosting operation to the second defrosting operation when it is detected that the operation time of the operation exceeds the predetermined time or when it is determined that the refrigerant temperature detected by the first heat exchange temperature sensor 51 exceeds the predetermined temperature. Switch to.
In the second defrosting operation, the first switching mechanism 3 and the second switching mechanism 4 are controlled to the same state as in the first defrosting operation. That is, the first switching mechanism 3 is controlled to the second state, and the second switching mechanism 4 is controlled to the third state. The first expansion mechanism 6 and the second expansion mechanism 14 are controlled to be in a fully open state. The third expansion mechanism 7 is controlled to the closed state. It also controls the fan drive motor 50a to a stopped state. If the heat source of the refrigerant flowing through the user-side heat exchanger 8 is air, the fan drive motor (not shown) of the fan that generates the air flow supplied to the user-side heat exchanger 8 is also controlled to be stopped. ..
The flow of the refrigerant at this time will be described below.
First, the low-pressure refrigerant sucked from the suction pipe 2a into the first compression section 2c is compressed by the first compression section 2c to become an intermediate-pressure refrigerant, and is discharged to the first intermediate refrigerant pipe 11a of the intermediate refrigerant pipe 11. .. The intermediate pressure refrigerant discharged to the first intermediate refrigerant pipe 11a is sucked into the second compression unit 2d via the first switching mechanism 3, the fourth intermediate refrigerant pipe 11d, and the third intermediate refrigerant pipe 11c. It is further compressed to become a high-pressure refrigerant, which is discharged to the discharge pipe 2b. Here, the refrigerant discharged from the compression mechanism 2 is compressed to a pressure exceeding the critical pressure of the refrigerant by the two-stage compression operation by the compression units 2c and 2d. The high-pressure refrigerant discharged to the discharge pipe 2b is sent to the first heat exchanger 40 through the second switching mechanism 4. The high-pressure refrigerant sent to the first heat exchanger 40 passes through the first heat exchanger 40, but in the first defrosting operation, the frost and ice adhering to the first heat exchanger 40 are almost melted. Therefore, the high-temperature and high-pressure refrigerant discharged from the second compression unit 2d passes through the first heat exchanger 40 in that state. Then, the high-pressure refrigerant that has passed through the first heat exchanger 40 passes through the first expansion mechanism 6 provided in the refrigerant pipe 12 and the second expansion mechanism 14 provided in the second heat exchanger guide pipe 13. , It will be sent to the second heat exchanger 60 and will pass through the second heat exchanger 60. At this time, the molten water generated by melting the frost and ice in the first heat exchanger 40 flows downward, and the frost and ice adhering to the second heat exchanger 60 are in a state of being easily melted. Therefore, the high-pressure refrigerant sent to the second heat exchanger 60 passes through the second heat exchanger 60 in that state. Then, the high-pressure refrigerant that has passed through the second heat exchanger 60 is decompressed to a low pressure by the defrosting expansion mechanism 16 described later via the first switching mechanism 3, and is sucked into the first compression unit 2c again. Will be done.
In the second defrosting operation, the high-temperature and high-pressure refrigerant discharged from the second compression unit 2d flows to the first heat exchanger 40, and the high-temperature and high-pressure refrigerant flowing to the first heat exchanger 40 is discharged. Since it flows to the second heat exchanger 60 without being depressurized and is sucked into the first compression unit 2c again, the pressure of the refrigerant is reduced in the refrigerant pipe 15 connecting the first switching mechanism 3 and the suction pipe 2a. Therefore, the above-mentioned expansion mechanism 16 for defrosting is provided. An electric expansion valve whose opening degree can be adjusted is used for the defrost expansion mechanism 16. In the second defrosting operation, the opening degree of the defrosting expansion mechanism 16 is adjusted, and in the defrosting expansion mechanism 16, the high-pressure refrigerant that has passed through the second heat exchanger 60 reaches the low pressure in the refrigeration cycle. The pressure is reduced. The defrosting expansion mechanism 16 is controlled to a closed state during a cooling operation and to a fully open state during a heating operation.
In the second defrosting operation, the high-temperature and high-pressure refrigerant discharged from the second compression unit 2d flows to the first heat exchanger 40, and the refrigerant that has passed through the first heat exchanger 40 flows to the second heat exchanger 60. , The refrigerant that has passed through the second heat exchanger 60 is sucked into the first compression unit 2c again (corresponding to the first refrigerant flow). Here, by flowing the high-temperature and high-pressure refrigerant discharged from the second compression unit 2d to the first heat exchanger 40, the frost and ice adhering to the first heat exchanger 40 can be melted and defrosted / deiced. .. Further, the high-temperature and high-pressure refrigerant that has flowed to the first heat exchanger 40 is allowed to flow to the second heat exchanger 60 without flowing to the user-side heat exchanger 8. As a result, the high-temperature and high-pressure refrigerant can flow to the second heat exchanger 60, so that the frost and ice adhering to the second heat exchanger 60 can be melted.
(5) Features (5-1) Conventionally, as disclosed in Patent Document 1 (Japanese Unexamined Patent Publication No. 2009-133581), a first heat exchanger that exchanges heat between a high-pressure refrigerant and air in a cooling mode and heat exchanges a low-pressure refrigerant and air in a heating mode. An air conditioner including a second heat exchanger that exchanges heat between the intermediate pressure refrigerant and air in the cooling mode and heat exchanges between the low pressure refrigerant and air in the heating mode has been proposed. In the air conditioner of Patent Document 1, the first heat exchanger and the second heat exchanger are defrosted by switching the switching mechanism to the cooling operation state in the defrost mode. In this air conditioner, the defrosting of the second heat exchanger is completed earlier than that of the first heat exchanger. Here, when the second heat exchanger is arranged below the first heat exchanger as in the present embodiment, the defrosting of the second heat exchanger is completed, but the first heat exchanger Since the defrosting of the first heat exchanger has not been completed, the frost and ice adhering to the surface of the first heat exchanger become molten water and flow through the second heat exchanger. There may be situations where you cannot switch to. That is, time is lost in the defrosting mode, and the return to the heating mode is delayed.
Therefore, in the defrosting mode of the present embodiment, in the second defrosting operation, the high-temperature and high-pressure refrigerant compressed by the second compression unit 2d flows to the first heat exchanger 40 and passes through the first heat exchanger 40. Refrigerant flow time zone (corresponding to the first refrigerant flow) in which the generated refrigerant flows into the second heat exchanger 60 and the refrigerant that has passed through the second heat exchanger 60 is sucked into the first compression unit 2c (corresponding to the first refrigerant flow). It has (corresponding to the first refrigerant flow time zone).
Here, frost and ice adhering to the first heat exchanger 40 are removed by forming a refrigerant flow in which the high-temperature and high-pressure refrigerant compressed and discharged by the second compression unit 2d flows to the first heat exchanger 40. Can be melted. Further, here, since the high-temperature and high-pressure refrigerant discharged from the second compression unit 2d flows to the first heat exchanger 40 without flowing to the second heat exchanger 60, de-icing of the second heat exchanger 60 / Defrosting / deicing of the first heat exchanger 40 can be performed before deicing. As a result, the melted water of frost and ice adhering to the surface of the first heat exchanger 40 flows to the second heat exchanger 60 arranged below the first heat exchanger 40. Therefore, the frost and ice adhering to the second heat exchanger 60 can be easily melted. Then, in a state where the second heat exchanger 60 can be easily defrosted, a refrigerant flow is formed in which the high-temperature and high-pressure refrigerant that has passed through the first heat exchanger 40 flows to the second heat exchanger 60. Therefore, the frost and ice adhering to the second heat exchanger 60 can be melted quickly.
Further, in the air conditioner disclosed in Patent Document 1, even if the defrosting of the first heat exchanger is completed earlier than the completion of the defrosting of the second heat exchanger, the defrosting of the first heat exchanger is completed. The high-temperature, high-pressure refrigerant discharged from the compression mechanism 2 will flow to the utilization unit side after passing through the first heat exchanger, so that the defrosting of the second heat exchanger can be performed. Completion will be delayed. On the other hand, in the present embodiment, as described above, the high-temperature and high-pressure refrigerant that has passed through the first heat exchanger 40 flows directly to the second heat exchanger 60, so that the second heat exchanger 60 Defrosting can be completed quickly.
As described above, in the present embodiment, the time loss in the defrosting mode can be suppressed, and the defrosting of the first heat exchanger 40 and the second heat exchanger 60 can be efficiently performed. Therefore, the defrosting mode You can reduce the time to do. As a result, it is possible to quickly return from the defrosting mode to the heating mode, and it is possible to take more time for the heating operation.
In the present embodiment, in order to generate such a refrigerant flow, the control unit 9 controls the first switching mechanism 3 to the second state and the second switching mechanism 4 to the third state in the defrosting mode. Is controlled. Further, the opening degree of the first expansion mechanism 6 provided in the refrigerant pipe 12 and the second expansion mechanism 14 provided in the second heat exchanger guide pipe 13 is adjusted.
(5-2) In the defrosting mode of the present embodiment, in the first defrosting operation, the high-temperature and high-pressure refrigerant compressed by the second compression unit 2d flows to the first heat exchanger 40 and passes through the first heat exchanger 40. Refrigerant flow time zone (corresponding to the second refrigerant flow), in which the refrigerant flows to the user side heat exchanger 8 and the refrigerant that has passed through the user side heat exchanger 8 is sucked into the first compression unit 2c 2 (corresponding to the refrigerant flow time zone).
In the present embodiment, in the defrosting mode, the refrigerant that has passed through the first heat exchanger 40 forms a refrigerant flow that flows to the utilization side heat exchanger 8, so that the utilization side heat exchanger including the utilization side heat exchanger 8 is formed. It is possible to create a time zone for recovering heat from the refrigerant flowing around 8.
Further, since the second defrosting operation is performed after the first defrosting operation, the second defrosting operation is performed in a state where the heat from the refrigerant flowing around the user side heat exchanger 8 including the user side heat exchanger 8 is recovered. Defrosting operation can be performed.
In the present embodiment, in order to generate such a refrigerant flow, the control unit 9 controls the first switching mechanism 3 to the second state and the second switching mechanism 4 to the third state in the defrosting mode. Is controlled. Further, the opening degree of the first expansion mechanism 6 provided in the refrigerant pipe 12 and the second expansion mechanism 14 provided in the second heat exchanger guide pipe 13 is adjusted (specifically, the first expansion mechanism 6). And the second expansion mechanism 14 is controlled to the fully open state). In the present embodiment, since the refrigerant flows to the utilization side heat exchanger 8 in the first defrosting operation, the high-pressure refrigerant compressed by the second compression unit 2d is used in the first heat exchanger 40. In the refrigerant flow, the refrigerant that has passed through the first heat exchanger 40 flows into the second heat exchanger 60 and the refrigerant that has passed through the second heat exchanger 60 is sucked into the first compression unit 2c. By further controlling 7 to the closed state, the refrigerant does not flow to the heat exchanger 8 on the user side.
(6) Modification example Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to the above embodiments and can be changed without departing from the gist of the invention.
(6-1) Modification A In the above embodiment, it has been described that the same refrigerant flow is generated all the time in each of the first defrosting operation and the second defrosting operation in the defrosting mode, but the present invention is not limited to this. That is, at any timing of the defrosting mode, the high-temperature and high-pressure refrigerant compressed by the second compression unit 2d flows to the first heat exchanger 40, and the refrigerant that has passed through the first heat exchanger 40 is the second heat. Refrigerant flow time zone in which the refrigerant that flows through the exchanger 60 and passes through the second heat exchanger 60 is sucked into the first compression unit 2c (corresponding to the first refrigerant flow) is generated, and the second compression unit 2d The high-temperature, high-pressure refrigerant compressed in the above flows into the first heat exchanger 40, the refrigerant that has passed through the first heat exchanger 40 flows into the user-side heat exchanger 8, and the refrigerant that has passed through the user-side heat exchanger 8 flows. It suffices to have a refrigerant flow time zone in which the refrigerant flow sucked into the first compression unit 2c (corresponding to the second refrigerant flow) is generated. Even in this case, the same effect as described above can be obtained.
(6-2) Modification B In the above embodiment, it has been described that the second expansion mechanism 14 is controlled in the closed state in the first defrosting operation. For example, the refrigerant that has passed through the first heat exchanger 40 and the first expansion mechanism 6 has passed through. The opening degree of the second expansion mechanism 14 may be adjusted so as to flow through the second heat exchanger 60. In the case of this modification B, the high-pressure refrigerant is decompressed to the intermediate pressure by the second expansion mechanism 14, and the intermediate-pressure refrigerant decompressed by the second expansion mechanism 14 is the second heat exchanger. After passing through 60, it flows to the refrigerant pipe 15 via the second intermediate refrigerant pipe 11b and the first switching mechanism 3. Then, the intermediate-pressure refrigerant flowing through the refrigerant pipe 15 is decompressed to a low pressure by the defrosting expansion mechanism 16 in the refrigerant pipe 15, and then sucked into the first compression unit 2c.
As described above, in addition to the above embodiment, in the first defrosting operation, the refrigerant flow generated in the second defrosting operation, that is, the high-temperature / high-pressure refrigerant compressed by the second compression unit 2d is the first heat. A refrigerant flow that flows to the exchanger 40, the refrigerant that has passed through the first heat exchanger 40 flows to the second heat exchanger 60, and the refrigerant that has passed through the second heat exchanger 60 is sucked into the first compression unit 2c is generated. There may be a refrigerant flow time zone.
In other words, the high-temperature, high-pressure refrigerant compressed by the second compression unit 2d flows to the first heat exchanger 40, the refrigerant that has passed through the first heat exchanger 40 flows to the second heat exchanger 60, and the second heat. Refrigerant flow time zone in which the refrigerant that has passed through the exchanger 60 is sucked into the first compression section 2c (corresponding to the first refrigerant flow) and the high-temperature / high-pressure refrigerant compressed by the second compression section 2d Flows to the first heat exchanger 40, the refrigerant that has passed through the first heat exchanger 40 flows to the utilization side heat exchanger 8, and the refrigerant that has passed through the utilization side heat exchanger 8 is sucked into the first compression unit 2c. The refrigerant flow (corresponding to the second refrigerant flow) may overlap.
In this modification B, since the second heat exchanger 60 can be defrosted even during the first defrosting operation, the execution time of the defrosting mode can be further shortened. Therefore, the return to the heating mode can be accelerated.
(6-3) Modification C In the above embodiment, the switching from the heating mode to the defrosting mode is performed by the temperature of the refrigerant flowing in the first heat exchanger 40 detected by the first heat exchange temperature sensor 51 or by the second heat exchange outlet temperature sensor 52. It has been explained that the temperature is based on the temperature of the refrigerant at the outlet of the second heat exchanger 60 that is detected, but the method is not limited to this. For example, it may be performed based on the elapsed time of the heating operation in the heating mode. In this case, when the elapsed time of the heating operation exceeds a predetermined time corresponding to the condition that frost is generated on the first heat exchanger 40 and the second heat exchanger 60, the first heat exchanger 40 and the second heat exchanger 40 and the second heat exchanger 60 are used. It is determined that frost has formed on the heat exchanger 60. Since the predetermined time depends on the temperature of the air as a heat source, it is preferable to set the predetermined time as a function of the temperature of the air detected by the air temperature sensor 53.
(6-4) Modification D FIG. 7 is a schematic configuration diagram of the heat exchange unit 105 according to this modified example.
In the above embodiment, as the compression mechanism 2, two compression units are connected in series to form a two-stage compression mechanism, but the present invention is not limited to this. For example, it may be a compression mechanism having one single-axis two-stage compression structure, a compression mechanism having more stages than a two-stage compression type such as a three-stage compression type, or further, multi-stage compression. It may be a parallel multi-stage compression type compression mechanism in which two or more types of compressors are connected in parallel.
The three-stage compression type compression mechanism has a low-stage side compression unit, a middle-stage side compression unit, and a high-stage side compression unit. Then, to explain the refrigerant flow focusing only on these compression portions, the refrigerant of the first intermediate pressure discharged from the lower stage side compression portion is transferred to the middle stage side compression portion connected to the rear stage side of the lower stage side compression portion. The refrigerant of the second intermediate pressure higher than the first intermediate pressure, which is sucked and discharged from the middle stage side compression part, is sucked into the high stage side compression part connected to the rear stage side of the middle stage side compression part. become. The refrigerant discharged from the high-stage compression unit is discharged to the discharge pipe 2b as a high-pressure refrigerant in the refrigeration cycle.
When the three-stage compression type compression mechanism is used as described above, it is preferable to provide a plurality of second heat exchangers 60 (here, two) as shown in FIG. That is, in this modification, instead of the heat exchange unit 5 of the above embodiment, a heat exchange unit 105 having a first heat exchanger 40 and a plurality of second heat exchangers 60 can be adopted. The plurality of second heat exchangers 60 are arranged so as to be arranged in the vertical direction (vertical direction). In FIG. 7, the second heat exchanger 60 arranged on the upper stage side is referred to as an upper stage side heat exchanger 60a, and the second heat exchanger 60 arranged on the lower stage side is referred to as a lower stage side heat exchanger 60b.
The flow of the refrigerant flowing through the heat exchange unit 105 when the three-stage compression type compression mechanism is used will be briefly described. First, during the cooling operation, the low-pressure refrigerant sucked into the lower-stage compression section through the suction pipe 2a is compressed by the lower-stage compression section and discharged, and flows into the lower-stage heat exchanger 60b (C1 in FIG. 7). See). Then, the refrigerant that has flowed into the lower heat exchanger 60b is sucked into the middle stage compression section, compressed by the middle stage side compression section, and flows into the upper stage side heat exchanger 60a (see C2 in FIG. 7). The refrigerant that has flowed into the upper heat exchanger 60a is sucked into the upper compression section. Then, the refrigerant sucked into the high-stage compression section is compressed by the high-stage compression section, discharged to the discharge pipe 2b, and flows into the first heat exchanger 40 (see C3 in FIG. 7). As described above, when the three-stage compression type compression mechanism is used, the second heat exchangers 60 are connected in series during the cooling operation. The flow of the refrigerant after flowing into the first heat exchanger 40 is the same as that of the above embodiment.
Next, during the heating operation, the refrigerant sent from the third expansion mechanism 7 flows in parallel to each of the first heat exchanger 40, the upper heat exchanger 60a, and the lower heat exchanger 60b ( See H1 in Figure 7). In this case, the refrigerant decompressed by the second expansion mechanism 14 flows to the upper heat exchanger 60a and the lower heat exchanger 60b, respectively. Then, the refrigerant flowing through these heat exchangers is sucked into the low-stage compression portion again. As described above, when the three-stage compression type compression mechanism is used, the second heat exchangers 60 are connected in parallel during the heating operation.
Next, during the second defrosting operation, the refrigerant discharged from the high-stage compression section flows into the first heat exchanger 40 (see D1 in FIG. 7). The refrigerant that has passed through the first heat exchanger 40 flows in parallel to each of the upper heat exchanger 60a and the lower heat exchanger 60b (see D2 in FIG. 7). Then, after passing through the upper heat exchanger 60a and the lower heat exchanger 60b, they are rejoined and sucked into the lower compression section. When the refrigerant flows through the second heat exchanger 60 even during the first defrosting operation, the refrigerant that has passed through the first heat exchanger 40 exchanges heat with the upper heat exchanger 60a and the lower heat exchanger 60 in the same manner as described above. It flows in parallel to each of the vessels 60b, passes through the upper heat exchanger 60a and the lower heat exchanger 60b, then rejoins and is sucked into the lower compression section.
As described above, the refrigerant may flow through the plurality of second heat exchangers 60 in parallel, but may also flow in series. That is, the refrigerant discharged from the high-stage compression section passes through the first heat exchanger 40 (see DD1 in FIG. 7), and the refrigerant that has passed through the first heat exchanger 40 first passes through the upper heat exchanger 40. It may flow through 60a (see DD2 in Figure 7) and then through the lower heat exchanger 60b (see DD3 in Figure 7). In this case, the refrigerant that has passed through the first heat exchanger 40 flows to the upper heat exchanger 60a before the lower heat exchanger 60b, so that the melted water of frost and ice adhering to the upper heat exchanger 60a. Can be flushed through the frost and ice adhering to the lower heat exchanger 60b, and the lower heat exchanger 60b can be efficiently defrosted / iced.
In the above, the case where there are a plurality of second heat exchangers 60 has been described by taking the case where a three-stage compression type compression mechanism is used as an example, but depending on other situations, the second heat exchanger 60 may be used as 2. In some cases, more than one unit may be provided.
(6-5) Modification E FIG. 8 is a schematic configuration diagram of an air conditioner 300 as an example of the refrigerating device according to the present modification E. FIG. 9 is a control block diagram of the control unit 90 according to the present modification E. FIG. 10 is a refrigerant pressure-enthalpy diagram showing a refrigeration cycle during cooling operation in the cooling mode of the air conditioner 300 according to the present modification E. FIG. 11 is a refrigerant pressure-enthalpy diagram showing a refrigeration cycle during heating operation in the heating mode of the air conditioner 300 according to the present modification E.
In the above embodiment, it has been described that the heat exchange unit 5 has two heat exchangers, a first heat exchanger 40 and a second heat exchanger 60, but the present invention is not limited to this, and heat exchange is not limited to this. The unit 5 may have a heat exchanger other than these as described in the modified example D. For example, instead of the heat exchange unit 5 of the above embodiment, as shown in FIG. 8, the heat exchange unit 305 of the air conditioner 300 according to the present modification E may be adopted. The heat exchange unit 305 further includes an economizer heat exchanger 70 and an overcooling heat exchanger 80 in addition to the first heat exchanger 40 and the second heat exchanger 60. It is assumed that these heat exchangers are integrated as in the above embodiment.
Hereinafter, the configuration of the refrigerant circuit 310 of the air conditioner 300 according to the present modification E in which the heat exchange unit 305 is adopted will be described. The same configurations as those in the above embodiment will be assigned the same numbers, and the description thereof will be omitted.
(6-5-1) Schematic configuration of refrigerant circuit 310 The refrigerant circuit 310 mainly includes a compression mechanism 2 having a first compression unit 2c and a second compression unit 2d, a first switching mechanism 3, a second switching mechanism 4, a heat exchange unit 305, a receiver 92, and a bridge. It has a circuit 110, a third expansion mechanism 307, and a heat exchanger 308 on the user side.
<Heat exchange unit 305> As described above, the heat exchange unit 305 includes a first heat exchanger 40, a second heat exchanger 60, an economizer heat exchanger 70, and an overcooling heat exchanger 80.
<Economizer heat exchanger 70> The economyr heat exchanger 70 includes a refrigerant cooled in the first heat exchanger 40 during the cooling operation, a refrigerant cooled by the user side heat exchanger 308 during the heating operation, and a refrigerant flowing through the economyr branch pipe 72 (specifically, the refrigerant). , A part of the refrigerant branched from the refrigerant cooled in the first heat exchanger 40 during the cooling operation or the refrigerant cooled in the utilization side heat exchanger 308 during the heating operation, and the intermediate pressure in the economizer inlet expansion mechanism 77. It is a heat exchanger that exchanges heat with the refrigerant after the pressure is reduced to the vicinity. More specifically, the economizer heat exchanger 70 is located on the upstream side of the receiver inlet side expansion mechanism 76 of the economizer refrigerant pipe 71 (specifically, when the second switching mechanism 4 is controlled to the third state, It is the position between the first heat exchanger 40 and the receiver inlet side expansion mechanism 76, and when the second switching mechanism 4 is controlled to the fourth state, the user side heat exchanger 308 and the receiver inlet side expansion mechanism 76 (Position between) and the refrigerant flowing through the economizer branch pipe 72, which will be described later. Specifically, the refrigerant cooled in the first heat exchanger 40 during the cooling operation or cooled by the user side heat exchanger 308 during the heating operation. A part of the refrigerant branched from the refrigerant that has been used is provided so as to exchange heat with the refrigerant after the pressure is reduced to near the intermediate pressure in the economizer inlet expansion mechanism 77), and both refrigerants are provided. It has flow paths that flow so as to face each other.
Here, between the first heat exchanger 40 and the user side heat exchanger 308, for flowing the refrigerant cooled by the first heat exchanger 40 or the user side heat exchanger 308 to the economizer heat exchanger 70. The economizer refrigerant pipe 71 is connected. The economizer refrigerant pipe 71 flows the refrigerant cooled by the first heat exchanger 40 or the user side heat exchanger 308 to the economizer heat exchanger 70 and then to the receiver 92. An economizer branch pipe 72 is connected to the economizer refrigerant pipe 71. The economizer branch pipe 72 branches a part of the refrigerant cooled by the first heat exchanger 40 or the user side heat exchanger 308, flows it through the economizer heat exchanger 70, and then returns it to the second compression unit 2d on the rear stage side. It is a possible refrigerant pipe. The economizer branch pipe 72 is connected to the third intermediate refrigerant pipe 11c. In this modification, in order to prevent the refrigerant flowing through the economizer branch pipe 72 from flowing to the second heat exchanger 60, a check mechanism 99 is placed on the downstream side of the second heat exchanger 60 during cooling operation. Is provided. The check mechanism 99 allows only the flow of the refrigerant from the second heat exchanger 60 to the second compression unit 2d, and prevents the refrigerant flowing from the economizer heat exchanger 70 from flowing into the second heat exchanger 60. It is a check valve that shuts off.
The economizer refrigerant pipe 71 is provided with a receiver inlet side expansion mechanism 76. The receiver inlet side expansion mechanism 76 is configured such that one end is connected to the economizer heat exchanger 70 and the other end is connected to the inlet of the receiver 92. The receiver inlet side expansion mechanism 76 transfers the high-pressure refrigerant flowing through the economizer refrigerant pipe 71 (that is, sent from the first heat exchanger 40 or the user side heat exchanger 308) to the economizer branch pipe in the economizer heat exchanger 70. It is a decompression mechanism for reducing the pressure to the vicinity of the intermediate pressure after heat exchange with the intermediate pressure refrigerant flowing through 72. More specifically, the receiver inlet side expansion mechanism 76 transfers the high-pressure refrigerant cooled by the first heat exchanger 40 to the refrigerant evaporator via the receiver 92 and the overcooling heat exchanger 80 during the cooling operation. The pressure is reduced to near the intermediate pressure before being sent to the utilization side heat exchanger 308, and during the heating operation, the high-pressure refrigerant cooled by the utilization side heat exchanger 308 is passed through the receiver 92 and the overcooling heat exchanger 80. Then, the pressure is reduced to near the intermediate pressure before being sent to the first heat exchanger 40 and the second heat exchanger 60 which function as a refrigerant evaporator. An electric expansion valve capable of adjusting the opening degree is used for the receiver inlet side expansion mechanism 76.
Further, the economizer branch pipe 72 is provided with an economizer branch expansion mechanism 77. Specifically, the economizer branch expansion mechanism 77 is provided at a portion connecting one end of the first heat exchanger 40 or the user side heat exchanger 308 and the upstream side of the economizer heat exchanger 70. The economizer branch expansion mechanism 77 is a decompression mechanism that reduces the high-pressure refrigerant cooled by the first heat exchanger 40 or the user-side heat exchanger 308 to near the intermediate pressure. More specifically, the economizer branch expansion mechanism 77 decompresses the high-pressure refrigerant cooled by the first heat exchanger 40 to near the intermediate pressure during the cooling operation, and cools it by the user side heat exchanger 308 during the heating operation. The high-pressure refrigerant is reduced to near the intermediate pressure. The economizer branch expansion mechanism 77 uses an electric expansion valve whose opening degree can be adjusted.
As described above, in this modification, the refrigerant sent from the first heat exchanger 40 functioning as the radiator of the refrigerant or the heat exchanger 308 on the user side and flowing through the economyr refrigerant pipe 71 flows through the economyr branch pipe 72. Since it is cooled by exchanging heat with the pressure refrigerant, it is per unit flow rate of the refrigerant sent to the utilization side heat exchanger 308 that functions as an evaporator, or the first heat exchanger 40 and the second heat exchanger 60. Cooling capacity can be increased. Further, the refrigerant flowing through the economizer branch pipe 72 is heated in the economizer heat exchanger 70, evaporated, and merged with the intermediate pressure refrigerant discharged from the first compression unit 2c, so that the refrigerant is sucked into the second compression unit 2d. The temperature of the refrigerant can be lowered. As a result, the power consumption of the second compression unit 21d can be reduced and the performance can be improved.
<Supercooled heat exchanger 80> The supercooling heat exchanger 80 is a heat exchanger that is arranged on the downstream side of the economizer heat exchanger 70 and puts the refrigerant that has passed through the economizer heat exchanger 70 into a supercooled state. The supercooling heat exchanger 80 includes a refrigerant flowing through the suction return pipe 95 (specifically, a refrigerant after being decompressed to a low pressure by the first suction expansion mechanism 96 and the second suction expansion mechanism 97 described later) and a receiver outlet. Intermediate pressure refrigerant flowing through tube 94 (sent from the economizer heat exchanger 70 to the user-side heat exchanger 308 as an evaporator, or to the first heat exchanger 40 and the second heat exchanger 60). It is configured to exchange heat and has a flow path in which both refrigerants face each other.
Here, the suction return pipe 95 is the suction side of the compression mechanism 2 (specifically, the suction side of the first compression unit 2c) via the supercooling heat exchanger 80 by extracting the refrigerant from the receiver 92. It is a refrigerant pipe that can be returned. One end of the suction return pipe 95 is such that a part of the refrigerant extracted from the receiver 92 passes through the overcooling heat exchanger 80 and returns to the suction side of the compression mechanism 2 (the suction side of the first compression unit 2c). It is configured to be connected to the receiver 92 and the other end to be connected to the suction pipe 2a. Further, the receiver outlet pipe 94 is a refrigerant pipe connected to the outlet side of the receiver 92 and the bridge circuit 110. The receiver outlet pipe 94 is a position between the receiver 92 and the upstream side of the supercooling heat exchanger 80 (specifically, the position of the refrigerant flowing through the suction return pipe 95 by branching a part of the refrigerant flowing through the receiver outlet pipe 94. It has a receiver outlet branch pipe 94a for merging with the refrigerant (flowing refrigerant).
The suction return pipe 95 (specifically, the position between the receiver 92 and the upstream end of the supercooling heat exchanger 80) is provided as an expansion mechanism for further reducing the refrigerant decompressed by the receiver inlet side expansion mechanism 76. The first suction expansion mechanism 96 is provided, and the receiver outlet branch pipe 94a is provided with a second suction expansion mechanism 97 as an expansion mechanism for further reducing the refrigerant decompressed by the receiver inlet side expansion mechanism 76. .. An electric expansion valve capable of adjusting the opening degree is used in the first suction expansion mechanism 96 and the second suction expansion mechanism 97. The first suction expansion mechanism 96 and the second suction expansion mechanism 97 transfer the refrigerant decompressed by the receiver inlet side expansion mechanism 76 to the suction side of the compression mechanism 2 (of the first compression unit 2c) via the supercooling heat exchanger 80. In order to return to the suction side), the pressure is reduced to the low pressure in the refrigeration cycle.
As described above, in this modification, the refrigerant that passes through the economizer heat exchanger 70 and flows to the receiver outlet pipe 94 (specifically, from the receiver 92, the third expansion mechanism 307, or the first expansion mechanism 306 and The low-pressure refrigerant (specifically, the refrigerant sent to the second expansion mechanism 314) passes through the suction return pipe 95 and passes through the first suction expansion mechanism 96 and the second suction expansion mechanism 97 to reduce the pressure to low pressure. By exchanging heat with the refrigerant that is returned to the first compression section 2c), it becomes overcooled. Therefore, the user-side heat exchanger 308 that functions as an evaporator, or the first heat exchanger 40 and the second heat The cooling capacity per unit flow rate of the refrigerant sent to the exchanger 60 can be increased.
<Receiver 92> The receiver 92 temporarily stores the refrigerant after being decompressed by the receiver inlet side expansion mechanism 76 so that the surplus refrigerant generated according to the operating state such as different circulation amounts of the refrigerant in the refrigerant circuit 310 can be stored. It is a container for storing. The receiver 92 is configured such that its inlet is connected to the economizer refrigerant pipe 71 and its outlet is connected to the receiver outlet pipe 94.
<Bridge circuit 110> The bridge circuit 110 is provided between the first heat exchanger 40 and the user side heat exchanger 308, and is connected to the economizer refrigerant pipe 71 and the receiver outlet pipe 94. The bridge circuit 110 includes a first inlet check mechanism 110a, a second inlet check mechanism 110b, an outlet check mechanism 110c, and a first expansion mechanism 306. The first inlet check mechanism 110a is a check valve that allows only the flow of refrigerant from the first heat exchanger 40 to the economizer refrigerant pipe 71 through the refrigerant pipe 112a. The refrigerant pipe 112a is a refrigerant pipe that connects the first heat exchanger 40 and the bridge circuit 110. The second inlet check mechanism 110b is a check valve that allows only the flow of refrigerant from the user side heat exchanger 308 to the economizer refrigerant pipe 71 through the refrigerant pipe 112b. The refrigerant pipe 112b is a refrigerant pipe that connects the heat exchanger 308 on the user side and the bridge circuit 110. The outlet check mechanism 110c is a check valve that allows only the flow of the refrigerant from the receiver outlet pipe 94 to the utilization side heat exchanger 308.
The first expansion mechanism 306 is a mechanism for reducing the pressure of the refrigerant, and an electric expansion valve capable of adjusting the opening degree is used. In this modification, the first expansion mechanism 306 is used instead of the first expansion mechanism 6 in the above embodiment. During the heating operation, the first expansion mechanism 306 sends the refrigerant decompressed by the receiver inlet side expansion mechanism 76 to the first heat exchanger 40 which functions as an evaporator via the receiver 92 and the supercooling heat exchanger 80. Further depressurize to low pressure in the refrigeration cycle. Further, the first expansion mechanism 306 adjusts the opening degree (specifically, it is controlled to the closed state), so that the refrigerant flowing from the first heat exchanger 40 during the cooling operation is the economizer refrigerant. It also has a function to flow only to the pipe 71.
In this modified example, as in the above embodiment, the second heat exchanger guide pipe 113 is provided in order to make the second heat exchanger 60 function as a refrigerant evaporator during the heating operation. Specifically, the second heat exchanger guide pipe 113 branches a part of the refrigerant flowing between the overcooling heat exchanger 80 and the first expansion mechanism 306 during the heating operation and the defrosting operation. 2 Refrigerant pipe that can flow through the heat exchanger 60, and is configured to connect the part between the overcooling heat exchanger 80 and the first expansion mechanism 306 and one end of the second heat exchanger 60. ing. The second heat exchanger guide pipe 113 is provided with a second expansion mechanism 314 for reducing the pressure of the refrigerant. The second expansion mechanism 314 is an electric expansion valve whose opening degree can be adjusted. In this modification, the second expansion mechanism 314 is used instead of the second expansion mechanism 14 in the above embodiment. The second expansion mechanism 314 reaches the low pressure in the refrigeration cycle before sending the refrigerant decompressed by the receiver inlet side expansion mechanism 76 to the second heat exchanger 60 via the supercooling heat exchanger 80 during the heating operation. Further reduce the pressure.
<Third expansion mechanism 307> The third expansion mechanism 307 is a mechanism for reducing the pressure of the refrigerant, and an electric expansion valve capable of adjusting the opening degree is used. In this modification, the third expansion mechanism 307 is used instead of the third expansion mechanism 7 in the above embodiment. The third expansion mechanism 307 is configured such that one end is connected to the bridge circuit 110 and the other end is connected to the utilization side heat exchanger 308. The third expansion mechanism 307 freezes the refrigerant decompressed by the receiver inlet side expansion mechanism 76 during the cooling operation before sending it to the utilization side heat exchanger 308 which functions as an evaporator via the supercooling heat exchanger 80. Further depressurize to low pressure in the cycle.
<User side heat exchanger 308> The user-side heat exchanger 308 is a heat exchanger that functions as a refrigerant evaporator or radiator. In this modification, the user side heat exchanger 308 is used instead of the user side heat exchanger 8 in the above embodiment. The user-side heat exchanger 308 is configured such that one end is connected to the third expansion mechanism 307 and the other end is connected to the second switching mechanism 4. The user-side heat exchanger 308 is compressed by the compression mechanism 2 (specifically, the second compression unit 2d) during the heating operation as an evaporator of the refrigerant cooled by the overcooling heat exchanger 80 during the cooling operation. It functions as a radiator for the refrigerant. Although not shown here, the user-side heat exchanger 308 is supplied with water or air as a heating source or a cooling source that exchanges heat with the refrigerant flowing through the user-side heat exchanger 308. ..
Further, in the air conditioner 300 of the present embodiment, the compression mechanism drive motor 21b, the first switching mechanism 3, the second switching mechanism 4, the fan drive motor 50a, and the first expansion of the first compression unit 2c and the second compression unit 2d It has a control unit 90 that controls the operation of each part of the air conditioner 300 such as various expansion mechanisms including the mechanism 306, the second expansion mechanism 314, and the third expansion mechanism 307.
The control unit 90 has a cooling mode, a heating mode, and a defrosting mode as in the above embodiment, and switches between these modes according to detection signals from various sensors.
(6-5-2) Operation of air conditioner 300 Hereinafter, the operation of the air conditioner 300 having the above configuration will be described with reference to FIGS. 8, 10 and 11. The operation control in the following cooling operation, heating operation, first defrosting operation, and second defrosting operation is performed by the above-mentioned control unit 90. Further, in the following description, "high pressure" means high pressure in the refrigeration cycle (that is, pressure at points d to f in FIG. 10 and pressure at points d, j, f in FIG. 11), and is "low pressure". Means the low pressure in the refrigeration cycle (ie, the pressure at points a, k, l, j in FIG. 10, the pressure at points a, k, l, e, o in FIG. 11), and what is "intermediate pressure"? , Means the intermediate pressure in the refrigeration cycle (ie, the pressure at points b, c, n, m, g, h, i in FIGS. 10 and 11).
Hereinafter, operation control in various modes will be described.
(6-5-2-1) Cooling mode In the cooling mode, the cooling operation is mainly performed. During the cooling operation, the first switching mechanism 3 is controlled to the first state, and the second switching mechanism 4 is controlled to the third state. The defrosting expansion mechanism 16, the first expansion mechanism 306 and the second expansion mechanism 314 are controlled to be closed. The opening degree of the third expansion mechanism 307, the receiver inlet side expansion mechanism 76, the economizer branch expansion mechanism 77, the first suction expansion mechanism 96, and the second suction expansion mechanism 97 is adjusted.
When the compression mechanism 2 is driven in the state of the refrigerant circuit 310, the low-pressure refrigerant (see point a in FIGS. 8 and 10) is first sucked into the first compression unit 2c on the front stage side through the suction pipe 2a. After being compressed to the intermediate pressure in the first compression section 2c, it is discharged to the intermediate refrigerant pipe 11 (first intermediate refrigerant pipe 11a) (see point b in FIGS. 8 and 10). The refrigerant discharged from the first compression unit 2c is sent to the second heat exchanger 60 through the first switching mechanism 3 and the second intermediate refrigerant pipe 11b. The refrigerant sent to the second heat exchanger 60 is cooled by exchanging heat with air as a cooling source in the second heat exchanger 60, and is sucked into the second compression unit 2d through the third intermediate refrigerant pipe 11c. Will be done. The refrigerant cooled by the second heat exchanger 60 is returned from the economizer branch pipe 72 to the second compression section 2d on the rear stage side (see point n in FIGS. 8 and 10) and the third intermediate refrigerant pipe. It is further cooled by merging at 11c (see point c in FIGS. 8 and 10). The intermediate pressure refrigerant that has merged with the refrigerant returning from the economizer branch pipe 72 is sucked into the second compression unit 2d, further compressed in the second compression unit 2d, and discharged to the discharge pipe 2b (FIGS. 8 and 10). See point d). Here, the high-pressure refrigerant discharged from the second compression unit 2d is the compression unit 2c, By the two-stage compression operation by 2d, it is compressed to a pressure exceeding the critical pressure (Pcp at the critical point CP shown in FIG. 10). Then, the high-pressure refrigerant discharged from the second compression unit 2d is sent to the first heat exchanger 40, which functions as a radiator of the refrigerant, via the second switching mechanism 4. The high-pressure refrigerant sent to the first heat exchanger 40 is cooled by exchanging heat with air as a cooling source (see point e in FIGS. 8 and 10). A part of the high-pressure refrigerant cooled in the first heat exchanger 40 is branched into the economizer branch pipe 72. The high-pressure refrigerant flowing through the economizer branch pipe 72 is decompressed to near the intermediate pressure by the economizer branch expansion mechanism 77, and then sent to the economizer heat exchanger 70 (see point m in FIGS. 8 and 10). On the other hand, the high-pressure refrigerant flowing through the economizer refrigerant pipe 71 is also sent to the economizer heat exchanger 70. Then, the refrigerant flowing through the economizer branch pipe 72 and flowing into the economizer heat exchanger 70 is heated by exchanging heat with the high-pressure refrigerant flowing through the economizer refrigerant pipe 71 and flowing so as to face the refrigerant flowing through the economizer branch pipe 72. (See point n in FIGS. 8 and 10), as described above, the refrigerant joins the cooled intermediate pressure refrigerant in the second heat exchanger 60. On the other hand, the refrigerant flowing through the economizer refrigerant pipe 71 and flowing into the economizer heat exchanger 70 is cooled by exchanging heat with the intermediate pressure refrigerant flowing through the economizer branch pipe 72 (see points f in FIGS. 8 and 10). ). The high-pressure refrigerant cooled in the economizer heat exchanger 70 is decompressed to the intermediate pressure in the refrigeration cycle by the receiver inlet side expansion mechanism 76 (see point g in FIGS. 8 and 10) and temporarily enters the receiver 92. It can be stored. A part of the intermediate pressure refrigerant stored in the receiver 92 is branched into the suction return pipe 95. The refrigerant flowing through the suction return pipe 95 is decompressed to near low pressure in the first suction expansion mechanism 96 and then sent to the supercooling heat exchanger 80 (see point k in FIGS. 8 and 10). On the other hand, the remaining intermediate pressure refrigerant partially branched into the suction return pipe 95 passes through the receiver outlet pipe 94 (FIGS. 8 and 8). At point 10 (see point h), it flows into the supercooling heat exchanger 80 and exchanges heat with the refrigerant near the low pressure flowing through the suction return pipe 95 in the supercooling heat exchanger 80 to cool and enter the supercooled state (Fig. 10). 8 and point i in Figure 10). Here, a part of the refrigerant flowing through the receiver outlet pipe 94 branches to the receiver outlet branch pipe 94a and is depressurized to near the low pressure in the second suction expansion mechanism 97 (see point l in FIGS. 8 and 10). , Will join the suction return pipe 95. The refrigerant flowing through the suction return pipe 95 and flowing into the overcooling heat exchanger 80 exchanges heat with the refrigerant flowing through the receiver outlet pipe 94, is heated and evaporates, and presses the suction side (suction pipe 2a) of the compression mechanism 2. It will join the flowing refrigerant. The refrigerant cooled in the supercooling heat exchanger 80 is sent to the third expansion mechanism 307, decompressed by the third expansion mechanism 307 to become a low-pressure refrigerant, and functions as a refrigerant evaporator. (See point j in Figures 8 and 10). Then, the low-pressure refrigerant sent to the user-side heat exchanger 308 exchanges heat with air or water as a heating source to be heated and evaporates (see point a in FIGS. 8 and 10). Then, the low-pressure refrigerant heated and evaporated by the user-side heat exchanger 308 is sucked into the first compression unit 2c. It is sent to the utilization side heat exchanger 308, which acts as a refrigerant evaporator (see point j in FIGS. 8 and 10). Then, the low-pressure refrigerant sent to the user-side heat exchanger 308 exchanges heat with air or water as a heating source to be heated and evaporates (see point a in FIGS. 8 and 10). Then, the low-pressure refrigerant heated and evaporated by the user-side heat exchanger 308 is sucked into the first compression unit 2c. It is sent to the utilization side heat exchanger 308, which acts as a refrigerant evaporator (see point j in FIGS. 8 and 10). Then, the low-pressure refrigerant sent to the user-side heat exchanger 308 exchanges heat with air or water as a heating source to be heated and evaporates (see point a in FIGS. 8 and 10). Then, the low-pressure refrigerant heated and evaporated by the user-side heat exchanger 308 is sucked into the first compression unit 2c.
In the air conditioner 300, the cooling operation in the cooling mode is performed as described above. During the cooling operation, the first switching mechanism 3 is controlled to the first state and the second switching mechanism 4 is controlled to the third state. Therefore, the refrigerant is mainly the first compression unit 2c and the second heat exchanger 60. , 2nd compression section 2d, 1st heat exchanger 40, economizer heat exchanger 70, overcooling heat exchanger 80, 3rd expansion mechanism 307, and user side heat exchanger 308.
(6-5-2-2) Heating mode In the heating mode, the heating operation is mainly performed. During the heating operation, the first switching mechanism 3 is controlled to the second state, and the second switching mechanism 4 is controlled to the fourth state. The defrosting expansion mechanism 16 and the third expansion mechanism 307 are controlled to be fully open. The opening degree of the receiver inlet side expansion mechanism 76, the economizer branch expansion mechanism 77, the first suction expansion mechanism 96, the second suction expansion mechanism 97, the first expansion mechanism 306 and the second expansion mechanism 314 is adjusted.
When the compression mechanism 2 is driven in the state of the refrigerant circuit 310, the low-pressure refrigerant (see point a in FIGS. 8 and 11) is first sucked into the first compression unit 2c on the front stage side through the suction pipe 2a. After being compressed to the intermediate pressure in the first compression section 2c, it is discharged to the intermediate refrigerant pipe 11 (first intermediate refrigerant pipe 11a) (see point b in FIGS. 8 and 11). The intermediate pressure refrigerant discharged from the first compression unit 2c does not pass through the second heat exchanger 60 (that is, without being cooled), unlike during the cooling operation, and the first switching mechanism 3 and the first 4 It is sucked into the second compression section 2d on the rear stage side through the intermediate refrigerant pipe 11d. The refrigerant discharged from the first compression section 2c is cooled by merging with the refrigerant returned from the economizer branch pipe 72 to the second compression section 2d on the rear stage side (see points c in FIGS. 8 and 11). ). The intermediate pressure refrigerant discharged from the first compression unit 2c and merged with the refrigerant returning from the economizer branch pipe 72 is sucked into the second compression unit 2d, further compressed, and discharged to the discharge pipe 2b (FIG. 8). And see point d in Figure 11). Here, the high-pressure refrigerant discharged from the second compression unit 2d is the compression unit 2c, as in the cooling operation. By the two-stage compression operation by 2d, it is compressed to a pressure exceeding the critical pressure (Pcp at the critical point CP shown in FIG. 11). The high-pressure refrigerant discharged from the second compression unit 2d is sent to the user-side heat exchanger 308, which functions as a radiator of the refrigerant, via the second switching mechanism 4, and is combined with air or water as a cooling source. It is cooled by heat exchange (see point j in FIGS. 8 and 11). A part of the high-pressure refrigerant cooled in the user-side heat exchanger 308 is branched to the economizer branch pipe 72 via the third expansion mechanism 307 controlled to the fully open state. The high-pressure refrigerant flowing through the economizer branch pipe 72 is decompressed to near the intermediate pressure by the economizer branch expansion mechanism 77, and then sent to the economizer heat exchanger 70 (see point m in FIGS. 8 and 11). On the other hand, the high-pressure refrigerant flowing through the economizer refrigerant pipe 71 is also sent to the economizer heat exchanger 70. Then, the refrigerant flowing through the economizer branch pipe 72 and flowing into the economizer heat exchanger 70 is heated by exchanging heat with the high-pressure refrigerant flowing through the economizer refrigerant pipe 71 and flowing so as to face the refrigerant flowing through the economizer branch pipe 72. (See point n in FIGS. 8 and 11), as described above, the refrigerant merges with the refrigerant discharged from the first compression unit 2c. On the other hand, the refrigerant flowing through the economizer refrigerant pipe 71 and flowing into the economizer heat exchanger 70 is cooled by exchanging heat with the intermediate pressure refrigerant flowing through the economizer branch pipe 72 (see points f in FIGS. 8 and 11). ). The high pressure refrigerant cooled in the economizer heat exchanger 70 is decompressed by the receiver inlet side expansion mechanism 76 to the intermediate pressure in the refrigeration cycle (see point g in FIGS. 8 and 11) and temporarily into the receiver 92. It can be stored. A part of the refrigerant stored in the receiver 92 is branched into the suction return pipe 95. The refrigerant flowing through the suction return pipe 95 is decompressed to near low pressure by the first suction expansion mechanism 96 and then sent to the supercooling heat exchanger 80 (see point k in FIGS. 8 and 11). On the other hand, the remaining intermediate pressure refrigerant partially branched into the suction return pipe 95 passes through the receiver outlet pipe 94 (FIGS. 8 and 11). (Refer to point h), it flows into the supercooling heat exchanger 80, exchanges heat with the refrigerant near the low pressure flowing through the suction return pipe 95, and is cooled to become a supercooled state (point i in FIGS. 8 and 11). See). Here, a part of the refrigerant flowing through the receiver outlet pipe 94 branches to the receiver outlet branch pipe 94a and is depressurized to near the low pressure in the second suction expansion mechanism 97 (see point l in FIGS. 8 and 11). , Will join the suction return pipe 95. The refrigerant that has flowed through the suction return pipe 95 and has flowed into the overcooling heat exchanger 80 exchanges heat with the refrigerant that flows through the receiver outlet pipe 94, is heated, and flows through the suction side (suction pipe 2a) of the compression mechanism 2. Will join in. Part of the refrigerant cooled in the supercooled heat exchanger 80 is sent to the second expansion mechanism 314, becomes a low-pressure refrigerant in the second expansion mechanism 314 (see point o in FIGS. 8 and 11), and the second Sent to heat exchanger 60. The remaining refrigerant cooled in the supercooling heat exchanger 80 and partially sent to the second expansion mechanism 314 is sent to the first expansion mechanism 306 and becomes a low-pressure refrigerant in the first expansion mechanism 306 (FIGS. 8 and 8). (See point e at 11), sent to the first heat exchanger 40. The refrigerant sent to the second heat exchanger 60 exchanges heat with air as a heating source in the second heat exchanger 60 to be heated and evaporated (see point a in FIGS. 8 and 11). On the other hand, the refrigerant sent to the first heat exchanger 40 is heated and evaporated by exchanging heat with the air as a heat reduction in the first heat exchanger 40 (see point a in FIGS. 8 and 11). .. Then, the low-pressure refrigerants heated and evaporated in the first heat exchanger 40 and the second heat exchanger 60, respectively, merge and are sucked into the first compression unit 2c. The refrigerant that has flowed into the overcooling heat exchanger 80 exchanges heat with the refrigerant flowing through the receiver outlet pipe 94, is heated, and joins the refrigerant flowing through the suction side (suction pipe 2a) of the compression mechanism 2. .. Part of the refrigerant cooled in the supercooled heat exchanger 80 is sent to the second expansion mechanism 314, becomes a low-pressure refrigerant in the second expansion mechanism 314 (see point o in FIGS. 8 and 11), and the second Sent to heat exchanger 60. The remaining refrigerant cooled in the supercooling heat exchanger 80 and partially sent to the second expansion mechanism 314 is sent to the first expansion mechanism 306 and becomes a low-pressure refrigerant in the first expansion mechanism 306 (FIGS. 8 and 8). (See point e at 11), sent to the first heat exchanger 40. The refrigerant sent to the second heat exchanger 60 exchanges heat with air as a heating source in the second heat exchanger 60 to be heated and evaporated (see point a in FIGS. 8 and 11). On the other hand, the refrigerant sent to the first heat exchanger 40 is heated and evaporated by exchanging heat with the air as a heat reduction in the first heat exchanger 40 (see point a in FIGS. 8 and 11). .. Then, the low-pressure refrigerants heated and evaporated in the first heat exchanger 40 and the second heat exchanger 60, respectively, merge and are sucked into the first compression unit 2c. The refrigerant that has flowed into the overcooling heat exchanger 80 exchanges heat with the refrigerant flowing through the receiver outlet pipe 94, is heated, and joins the refrigerant flowing through the suction side (suction pipe 2a) of the compression mechanism 2. .. A part of the refrigerant cooled in the supercooling heat exchanger 80 is sent to the second expansion mechanism 314 and becomes a low pressure refrigerant in the second expansion mechanism 314 (see point o in FIGS. 8 and 11), and the second Sent to heat exchanger 60. The remaining refrigerant cooled in the supercooling heat exchanger 80 and partially sent to the second expansion mechanism 314 is sent to the first expansion mechanism 306 and becomes a low-pressure refrigerant in the first expansion mechanism 306 (FIGS. 8 and 8). (See point e at 11), sent to the first heat exchanger 40. The refrigerant sent to the second heat exchanger 60 exchanges heat with air as a heating source in the second heat exchanger 60 to be heated and evaporated (see point a in FIGS. 8 and 11). On the other hand, the refrigerant sent to the first heat exchanger 40 is heated and evaporated by exchanging heat with the air as a heat reduction in the first heat exchanger 40 (see point a in FIGS. 8 and 11). .. Then, the low-pressure refrigerants heated and evaporated in the first heat exchanger 40 and the second heat exchanger 60, respectively, merge and are sucked into the first compression unit 2c. It heats up and evaporates by exchanging heat with air as a heat reduction (see point a in FIGS. 8 and 11). Then, the low-pressure refrigerants heated and evaporated in the first heat exchanger 40 and the second heat exchanger 60, respectively, merge and are sucked into the first compression unit 2c. It heats up and evaporates by exchanging heat with air as a heat reduction (see point a in FIGS. 8 and 11). Then, the low-pressure refrigerants heated and evaporated in the first heat exchanger 40 and the second heat exchanger 60, respectively, merge and are sucked into the first compression unit 2c.
In the air conditioner 300, the heating operation in the heating mode is performed as described above. During the heating operation, the first switching mechanism 3 is controlled to the second state and the second switching mechanism 4 is controlled to the fourth state. Therefore, the refrigerant is mainly used in the first compression unit 2c, the second compression unit 2d, and the like. User side heat exchanger 308, 3rd expansion mechanism 307, economizer heat exchanger 70, overcooling heat exchanger 80, 1st expansion mechanism 306 and 2nd expansion mechanism 314, 1st heat exchanger 40 and 2nd heat exchanger It will flow in the order of 60.
(6-5-2-3) Defrost mode The conditions for switching from the heating mode to the defrosting mode and the conditions for switching from the defrosting mode to the heating mode are the same as those in the above embodiment. Hereinafter, various operations in the defrosting mode in this modification will be described. In the defrosting mode of this modification, the third defrosting operation and the fourth defrosting operation are mainly performed. Specifically, the fourth defrosting operation is performed after the third defrosting operation is performed. In this modification, the third defrosting operation is performed instead of the first defrosting operation of the above embodiment, and the fourth defrosting operation is performed instead of the second defrosting operation.
(6-5-2-3-1) Third defrosting operation In the third defrosting operation, the first switching mechanism 3 is controlled to the second state, and the second switching mechanism 4 is controlled to the third state. The opening degree of the receiver inlet side expansion mechanism 76, the first expansion mechanism 306 and the third expansion mechanism 307 is adjusted. The economizer branch expansion mechanism 77, the first suction expansion mechanism 96, and the second expansion mechanism 314 are controlled to be closed. The second suction expansion mechanism 97 is controlled to the fully open state. It also controls the fan drive motor 50a to a stopped state. If the heat source of the refrigerant flowing through the user-side heat exchanger 308 is air, the fan drive motor (not shown) of the fan that generates the air flow supplied to the user-side heat exchanger 308 is also controlled to be stopped. ..
The flow of the refrigerant in the state of the refrigerant circuit 310 will be described below.
First, the low-pressure refrigerant sucked into the first compression section 2c on the front stage side through the suction pipe 2a is compressed by the first compression section 2c to become an intermediate pressure refrigerant, and becomes the first intermediate refrigerant pipe 11a of the intermediate refrigerant pipe 11. It is discharged. The intermediate pressure refrigerant discharged to the first intermediate refrigerant pipe 11a is further sucked into the second compression unit 2d via the first switching mechanism 3, the fourth intermediate refrigerant pipe 11d and the third intermediate refrigerant pipe 11c. It is compressed and becomes a high-pressure refrigerant. Here, the refrigerant discharged from the compression mechanism 2 is the compression unit 2c, By the two-stage compression operation by 2d, it is compressed to a pressure exceeding the critical pressure of the refrigerant. The high-pressure refrigerant compressed by the second compression unit 2d is discharged to the discharge pipe 2b and sent to the first heat exchanger 40 via the second switching mechanism 4. When the high-pressure refrigerant sent to the first heat exchanger 40 passes through the first heat exchanger 40, it exchanges heat with frost and ice adhering to the first heat exchanger 40 to dissipate heat and generate high pressure. It becomes a liquid refrigerant and melts frost and ice. A part of the high-pressure liquid refrigerant that has passed through the first heat exchanger 40 is branched to the economizer branch pipe 72, and the remaining refrigerant is sent to the first expansion mechanism 306. The refrigerant flowing through the economizer branch pipe 72 passes through the economizer heat exchanger 70 (note that the economizer branch expansion mechanism 77 is controlled to be closed and the refrigerant does not flow through the economizer branch pipe 72, so that the economizer heat exchanger No heat exchange takes place in 70), it is sent to the receiver inlet side expansion mechanism 76, and the pressure is reduced to a low pressure by the receiver inlet side expansion mechanism 76. The refrigerant decompressed to a low pressure by the receiver inlet side expansion mechanism 76 is temporarily stored in the receiver 92. The low-pressure gas refrigerant in the receiver 92 flows to the suction return pipe 95 via the receiver outlet branch pipe 94a, and flows through the second suction expansion mechanism 97 and the supercooling heat exchanger 80 (note that the receiver outlet branch pipe). Since no refrigerant is flowing through the receiver outlet pipe 94 except 94a, heat exchange is not performed in the supercooling heat exchanger 80), and the refrigerant returns to the suction side (suction pipe 2a) of the first compression unit 2c. On the other hand, the refrigerant sent to the first expansion mechanism 306 is decompressed to near the intermediate pressure by the first expansion mechanism 306 and sent to the third expansion mechanism 307. The intermediate pressure refrigerant sent to the third expansion mechanism 7 is depressurized by the third expansion mechanism 307 to become a low pressure refrigerant. The refrigerant decompressed to a low pressure by the third expansion mechanism 307 is heated and evaporated by exchanging heat with air or water in the user side heat exchanger 308. The gas refrigerant evaporated in the user-side heat exchanger 308 is returned to the suction side (suction pipe 2a) of the first compression unit 2c again via the second switching mechanism 4. still,
In the defrosting mode, the third defrosting operation is first performed as described above.
In the third defrosting operation, the high-pressure refrigerant compressed by the second compression unit 2d flows to the first heat exchanger 40, and the refrigerant that has passed through the first heat exchanger 40 flows to the user side heat exchanger 308, and the user side. A refrigerant flow (corresponding to the second refrigerant flow) in which the refrigerant that has passed through the heat exchanger 308 is sucked into the first compression unit 2c is generated. Here, the high-temperature and high-pressure refrigerant discharged from the second compression unit 2d can be flowed through the first heat exchanger 40 to melt and defrost the frost and ice adhering to the first heat exchanger 40. Furthermore, by forming a refrigerant flow such that the refrigerant compressed by the second compression unit 2d passes through the utilization side heat exchanger 308, the periphery of the utilization side heat exchanger 308 including the utilization side heat exchanger 308 is formed. The heat from the flowing refrigerant can be recovered. Further, by flowing a part of the refrigerant from the first heat exchanger 40 to the user side heat exchanger 308 to the economizer branch pipe 72, the refrigerant stored in the receiver 92 is transferred to the suction side (first compression unit) of the compression mechanism 2. It can be returned to the suction side of 2c).
(6-5-2-3-2) 4th defrosting operation The switching from the third defrosting operation to the fourth defrosting operation is triggered when the defrosting of the first heat exchanger 40 is almost completed. Specifically, the defrosting of the first heat exchanger 40 is considered to be almost completed, or the predetermined temperature of the refrigerant flowing in the first heat exchanger 40 is set in advance, and the first defrosting is performed. From the third defrosting operation to the fourth defrosting operation when it is detected that the operation time of the operation exceeds the predetermined time or when it is determined that the refrigerant temperature detected by the first heat exchange temperature sensor 51 exceeds the predetermined temperature. Switch to.
In the fourth defrosting operation, the first switching mechanism 3 and the second switching mechanism 4 are kept controlled in the same state as in the first defrosting operation. That is, the first switching mechanism 3 is controlled to the second state, and the second switching mechanism 4 is controlled to the third state. The first expansion mechanism 306 and the second expansion mechanism 314 are controlled to be fully open. The third expansion mechanism 307, the economizer branch expansion mechanism 77, the first suction expansion mechanism 96, and the second suction expansion mechanism 97 are controlled to be in a closed state. The opening degree of the receiver inlet side expansion mechanism 76 and the defrost expansion mechanism 16 is adjusted. It also controls the fan drive motor 50a to a stopped state. If the heat source of the refrigerant flowing through the user-side heat exchanger 308 is air, the fan drive motor (not shown) of the fan that generates the air flow supplied to the user-side heat exchanger 308 is also controlled to be stopped. ..
Hereinafter, the flow of the refrigerant in the state of the refrigerant circuit 310 will be described.
First, the low-pressure refrigerant sucked into the first compression section 2c on the front stage side through the suction pipe 2a is compressed by the first compression section 2c to become an intermediate pressure refrigerant, and becomes the first intermediate refrigerant pipe 11a of the intermediate refrigerant pipe 11. It is discharged. The intermediate pressure refrigerant discharged to the first intermediate refrigerant pipe 11a is further sucked into the second compression unit 2d via the first switching mechanism 3, the fourth intermediate refrigerant pipe 11d and the third intermediate refrigerant pipe 11c. It is compressed and becomes a high-pressure refrigerant. Here, the refrigerant discharged from the compression mechanism 2 is the compression unit 2c, By the two-stage compression operation by 2d, it is compressed to a pressure exceeding the critical pressure of the refrigerant. The high-pressure refrigerant compressed by the second compression unit 2d is discharged to the discharge pipe 2b and sent to the first heat exchanger 40 via the second switching mechanism 4. The high-pressure refrigerant sent to the first heat exchanger 40 passes through the first heat exchanger 40, but in the third defrosting operation, the frost and ice adhering to the first heat exchanger 40 are almost melted. Therefore, the high-temperature and high-pressure refrigerant discharged from the second compression unit 2d passes through the first heat exchanger 40 in that state. Then, a part of the high-temperature and high-pressure refrigerant that has passed through the first heat exchanger 40 is branched into the economizer refrigerant pipe 71, and the remaining refrigerant passes through the first expansion mechanism 306 and the second expansion mechanism 314 in the fully opened state. Then, it is sent to the second heat exchanger 60. The high-pressure refrigerant flowing through the economizer refrigerant pipe 71 flows through the economizer heat exchanger 70 (note that the economizer branch expansion mechanism 77 is controlled to be closed and the refrigerant does not flow through the economizer branch pipe 72, so that the economizer heat exchanger No heat exchange takes place at 70), and it is sent to the receiver inlet side expansion mechanism 76. The high-pressure refrigerant sent to the receiver inlet-side expansion mechanism 76 is decompressed to a low pressure by the receiver inlet-side expansion mechanism 76 and stored in the receiver 92. On the other hand, the high-pressure refrigerant sent to the second heat exchanger 60 passes through the second heat exchanger 60. At this time, the molten water generated by melting the frost and ice in the first heat exchanger 40 flows downward, and the frost and ice adhering to the second heat exchanger 60 are in a state of being easily melted. Therefore, the high-pressure refrigerant sent to the second heat exchanger 60 passes through the second heat exchanger 60 in that state. Then, the high-pressure refrigerant that has passed through the second heat exchanger 60 is decompressed to a low pressure by the defrosting expansion mechanism 16 and returned to the suction side of the compression mechanism 2 (the suction side of the first compression unit 2c) again. ..
In the defrosting mode, the fourth defrosting operation is performed after the third defrosting operation is performed as described above.
As described above, in this modification, in the fourth defrosting operation, the high-temperature and high-pressure refrigerant compressed by the second compression unit 2d flows into the first heat exchanger 40 and passes through the first heat exchanger 40. Refrigerant flow time zone (corresponding to the first refrigerant flow) in which the refrigerant flows to the second heat exchanger 60 and the refrigerant that has passed through the second heat exchanger 60 is sucked into the first compression unit 2c (corresponding to the first refrigerant flow). 1 (corresponding to the refrigerant flow time zone). Here, frost and ice adhering to the first heat exchanger 40 are removed by forming a refrigerant flow in which the high-temperature and high-pressure refrigerant compressed and discharged by the second compression unit 2d flows to the first heat exchanger 40. Can be melted. Further, here, since the high-temperature and high-pressure refrigerant discharged from the second compression unit 2d flows to the first heat exchanger 40 without flowing to the second heat exchanger 60, de-icing of the second heat exchanger 60 / Defrosting / deicing of the first heat exchanger 40 can be performed before deicing. As a result, the melted water of frost and ice adhering to the surface of the first heat exchanger 40 flows to the second heat exchanger 60 arranged below the first heat exchanger 40. Therefore, the frost and ice adhering to the second heat exchanger 60 can be easily melted. Then, in a state where such defrosting of the second heat exchanger 60 can be easily performed, a refrigerant flow is formed in which the high-temperature and high-pressure refrigerant that has passed through the first heat exchanger 40 flows to the second heat exchanger 60. Therefore, the frost and ice adhering to the second heat exchanger 60 can be melted quickly. Further, in the air conditioner disclosed in Patent Document 1 of the above embodiment, even if the defrosting of the first heat exchanger is completed earlier than the completion of the defrosting of the second heat exchanger, the first heat exchange is completed. The high-temperature, high-pressure refrigerant discharged from the compression mechanism 2 for defrosting the vessel will flow to the third heat exchanger side (utilization unit side) after passing through the first heat exchanger. Therefore, the completion of defrosting of the second heat exchanger will be delayed. On the other hand, in this modification, as described above, the high-temperature and high-pressure refrigerant that has passed through the first heat exchanger 40 flows directly to the second heat exchanger 60, so that the second heat exchanger 60 Defrosting can be completed quickly.
As described above, in this modification, the time loss in the defrosting mode can be suppressed, and the defrosting of the first heat exchanger 40 and the second heat exchanger 60 can be efficiently performed, so that the defrosting mode can be performed. The defrosting operation time in the above can be shortened. As a result, it is possible to quickly return from the defrosting mode to the heating mode, and it is possible to take more time for the heating operation. In this modification, in order to generate such a refrigerant flow, the control unit 9 controls the first switching mechanism 3 to the second state and the second switching mechanism 4 to the third state in the defrosting mode. Is controlled. Further, the bridge circuit 110 (in this modification, the refrigerant pipe connecting the first heat exchanger 40 and the user side heat exchanger 308, including the bridge circuit 110, fulfills the function of the refrigerant pipe 12 in the above embodiment). The opening degree of the first expansion mechanism 306 provided in the first expansion mechanism 306 and the second expansion mechanism 314 provided in the second heat exchanger guide pipe 113 is adjusted.
Further, in this modification, in the defrosting mode, in the third defrosting operation, the high-temperature and high-pressure refrigerant compressed by the second compression unit 2d flows to the first heat exchanger 40, and the first heat exchanger 40 is operated. Refrigerant flow time in which the passed refrigerant flows to the user-side heat exchanger 8 and the refrigerant that has passed through the user-side heat exchanger 8 is sucked into the first compression unit 2c (corresponding to the second refrigerant flow). It has a zone (corresponding to the second refrigerant flow time zone). In this modification, in the defrosting mode, the refrigerant that has passed through the first heat exchanger 40 forms a refrigerant flow that flows to the utilization side heat exchanger 308, so that the utilization side heat exchanger including the utilization side heat exchanger 308 is formed. It is possible to create a time zone for recovering heat from the refrigerant flowing around 308. Further, since the fourth defrosting operation is performed after the third defrosting operation, the fourth defrosting operation is performed in a state where the heat from the refrigerant flowing around the user side heat exchanger 308 including the user side heat exchanger 308 is recovered. Defrosting operation can be performed. In this modification, in order to generate such a refrigerant flow, the control unit 9 controls the first switching mechanism 3 to the second state and the second switching mechanism 4 to the third state in the defrosting mode. Is controlled. Further, the opening degree of the first expansion mechanism 306 provided in the bridge circuit 110 and the second expansion mechanism 314 provided in the second heat exchanger guide tube 113 is adjusted (specifically, the first expansion mechanism 306). And the second expansion mechanism 314 is controlled to the fully open state). In the present embodiment, since the refrigerant flows to the user side heat exchanger 308 in the third defrosting operation, the high temperature / high pressure refrigerant compressed by the second compression unit 2d exchanges the first heat. In the refrigerant flow, the refrigerant flowing through the container 40 flows through the first heat exchanger 40 flows into the second heat exchanger 60, and the refrigerant passing through the second heat exchanger 60 is sucked into the first compression unit 2c. By further controlling the expansion mechanism 307 to the closed state, the refrigerant does not flow to the heat exchanger 308 on the user side.
(6-5-3) Other variants In addition to the above-described form, the economizer branch expansion mechanism 77 so that the superheat degree of the refrigerant at the outlet of the economizer heat exchanger 70 on the economizer branch pipe 72 side becomes the target value, that is, so-called superheat degree control is performed. The opening degree may be adjusted. In this case, the air conditioner 300 has a sensor for detecting (deriving) the degree of superheat of the refrigerant at the outlet of the economizer heat exchanger 70 on the economizer branch pipe 72 side.
Further, in the above-described embodiment, it has been explained that the second expansion mechanism 314 is in a fully open state in the third defrosting operation, but as described in the modified example B, for example, it passes through the first heat exchanger 40. Then, the opening degree of the second expansion mechanism 314 may be adjusted so that the refrigerant that has passed through the first expansion mechanism 306 flows into the second heat exchanger 60. In this case, the same effect as that of the modified example B can be obtained.
(6-6) Modification F In addition to the configuration of the above embodiment, a configuration having a receiver as described in the modified example E may be used. For example, when the heat source of the refrigerant flowing through the user-side heat exchanger 8 is air, the fan that generates the air flow supplied to the user-side heat exchanger 8 is stopped during the first defrosting operation. The liquid refrigerant that has not been vaporized by the side heat exchanger 8 may be temporarily stored in the receiver. That is, the receiver in this case is arranged between the downstream side of the heat exchanger 8 on the utilization side in the refrigerant flow direction and the suction side of the compression mechanism 2.
(6-7) Modification G In the above embodiment, the first expansion mechanism 6 and the third expansion mechanism 7 are provided between the first heat exchanger 40 and the user side heat exchanger 8 (that is, the refrigerant pipe 12), but one of them is provided. Only may be provided. That is, one of the expansion mechanisms selected and provided may function as the first expansion mechanism provided in the first refrigerant pipe 12. In this case, one of the expansion mechanisms selected and provided is provided between the portion of the refrigerant pipe 12 connected to the second heat exchanger guide pipe 13 and the first heat exchanger 40. ..
In such a configuration, one of the selected expansion mechanisms decompresses the high-pressure refrigerant sent from the first heat exchanger 40 to a low pressure and sends it to the user heat exchanger 8 during the cooling operation in the cooling mode. During the heating operation in the heating mode, the high-pressure refrigerant sent from the user-side heat exchanger 8 is decompressed to a low pressure and sent to the first heat exchanger 40.
In the present invention, a plurality of heat exchangers are arranged side by side in the vertical direction, and various applications can be applied to a refrigerating apparatus having a heating mode.
1 Air conditioner (refrigerator) 2c 1st compression section 2d 2nd compression section 3 1st switching mechanism 4 2nd switching mechanism 6 1st expansion mechanism 8 User side heat exchanger (3rd heat exchanger) 9 Control unit 12 Refrigerant pipe (1st refrigerant pipe) 13 2nd heat exchanger guide pipe (2nd refrigerant pipe) 14 Second expansion mechanism 40 1st heat exchanger 60 Second heat exchanger 90 Control unit 110 bridge circuit 113 2nd heat exchanger guide pipe (2nd refrigerant pipe) 306 1st expansion mechanism 308 User side heat exchanger (3rd heat exchanger) 314 2nd expansion mechanism
<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2009-133581</text></patcit></p>
12 sheets
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Sheet 6 Sheet 7 Sheet 8 Sheet 9 Sheet 10 Sheet 11 Sheet 12
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| Document | Relation | Office | Cited during |
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| JP2023000853A | Cited by | Japan | Search report |
| JP2009133578A | Cites | Japan | Search report |
| JP2010043800A | Cites | Japan | Search report |
| JP2010139097A | Cites | Japan | Search report |
| JP2010156493A | Cites | Japan | Search report |
| US6880353B1 | Cites | United States of America | Search report |
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| 2011223323 | Japan | A | |
| JP20110223323 | – | – | – |
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| JP2013083395AThis record | Japan | A | |
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Numbers
- Publication
- 2013083395
- Publication, DOCDB
- 2013083395
- Publication, EPODOC
- JP2013083395
- Application
- 223323
- Application, DOCDB
- 2011223323
- Application, EPODOC
- JP20110223323
Titles2
- Japanese
- 冷凍装置
- English
- Refrigeration equipment
Classification
- IPC, 3
- F25B47 02
- F25B1 00
- F25B1 10