Air conditioner

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention has a refrigerating circuit including a compressor driven by an electric motor whose rotation speed is controlled by an inverter, and relates to an air conditioner suitable for mounting on an automobile, in particular, using the low temperature side of the refrigerating circuit to provide an inverter. Regarding an air conditioner having a cooling function.

【0002】

[Conventional technology]

In this type of air conditioner, the rotation speed of the compressor is controlled by controlling the rotation speed of the electric motor by an inverter according to the air conditioning load. Then, for example, in order to prevent the cooling load from being large and the input current value to the electric motor from becoming larger than the predetermined value, when the input current value becomes larger than the predetermined value, the rotation speed of the electric motor (resulting in this). The input current value is reduced by lowering the rotation speed of the compressor. The purpose of preventing the input current value to the electric motor from becoming larger than the predetermined value is also for the purpose of preventing the inverter from being damaged due to the overcurrent.

【0003】

However, in the above-mentioned conventional example, when the cooling load is large and the input current value becomes larger than a predetermined value, the rotation speed of the electric motor (compressor) is reduced, so that the cooling capacity of the refrigeration circuit is sharply reduced. There is a problem that it ends up.

【0004】

In order to solve this problem, Japanese Patent Application Laid-Open No. 10-115448 discloses an air conditioner in which the input current to the electric motor is reduced without a sharp decrease in cooling capacity.

【0005】

In this air conditioner, the rotation speed of the electric motor (compressor) and the input current value to the electric motor correlate with the torque (load torque) of the compressor. By reducing the torque of the compressor based on the action of increasing the rotation speed of the electric motor (compressor), the rotation speed of the electric motor (compressor) is maintained even if the input current value to the electric motor is reduced. is there.

【0006】

Specifically, this air conditioner reduces the low pressure of the refrigeration circuit in order to keep the input current value of the electric motor that drives the compressor below a predetermined value (prevents inverter damage due to overcurrent), or By controlling to reduce the amount of air blown by the inverter, the torque of the compressor is reduced to increase the number of revolutions of the electric motor (compressor), and while suppressing a sudden decrease in cooling capacity, the electric motor is supplied. Decrease the input current value.

【0007】

Further, in order to prevent damage to the inverter due to overcurrent, a technique for cooling the inverter using the low temperature side of the refrigerating circuit has been proposed and implemented. This is useful for reducing the size and cost of the entire air conditioner because a dedicated cooling means is not provided separately from the refrigerating circuit to cool the inverter.

【0008】

[Problems to be Solved by the Invention]

However, conventional air conditioners, including the devices disclosed in Japanese Patent Application Laid-Open No. 10-115448, generate heat from the inverter even if the electric motor is operated below the input current value by limiting the input current value. In reality, it is often possible that the amount of heat taken by the low temperature side of the refrigeration circuit is exceeded. If the inverter is not sufficiently cooled by the low temperature side of the refrigeration circuit in this way, even if the input current value of the electric motor is limited and the operation is performed below the input current value, the inverter may be damaged in the end. is there.

【0009】

An object of the present invention is to provide an air conditioner capable of reliably avoiding damage to an inverter by preventing an excessive temperature rise of the inverter.

【0010】

[Means for solving problems]

According to the present invention, the following air conditioners (1) to (9) can be obtained.

【0011】

(1) A compressor that compresses the refrigerant to high temperature and high pressure, a condenser that condenses and liquefies the high temperature and high pressure refrigerant, an expansion valve that decompresses the condensed liquefied refrigerant, and an inverter that evaporates and vaporizes the decompressed refrigerant. An air conditioner having a refrigerating circuit, wherein the compressor is driven by an electric motor whose rotation speed is controlled by an inverter, and the inverter is cooled by using the refrigerating circuit. The temperature determining means for determining whether or not (T) is higher than the first predetermined value (Tset1) and the determination result by the temperature determining means are "the temperature (T) of the inverter is the first predetermined value (T). An air-conditioning apparatus comprising: a compressor rotation speed control means for lowering the rotation speed of the compressor via the inverter and the electric motor when the value is higher than Tset1).

【0012】

(2) The air conditioner according to (1), wherein the electric motor and the inverter are integrally configured with the compressor.

【0013】

(3) The temperature determining means also determines whether or not the temperature (T) of the inverter is higher than the second predetermined value (Tset2), which is higher than the first predetermined value (Tset1). When the determination result by the temperature determining means is "the temperature (T) of the inverter is higher than the second predetermined value (Tset2)", the compressor is stopped via the inverter and the electric motor. The air conditioner according to (1) or (2), further comprising a compressor rotation stopping means.

【0014】

(4) In the compressor rotation speed control means, when the determination result by the temperature determination means at the time of starting the compressor is "the temperature (T) of the inverter is higher than the first predetermined value (Tset1)". In addition, after the compressor is started, the number of revolutions of the compressor is kept lowered via the inverter and the electric motor until the temperature (T) of the inverter becomes equal to or lower than the first predetermined value (Tset1). The air conditioner according to any one of (1) to (3).

【0015】

(5) The compressor suction pressure detecting means for detecting the suction pressure (Ps) of the compressor is further provided, and the temperature determining means is the calculated temperature (Ps) of the inverter calculated according to the suction pressure (Ps) of the compressor. It also determines whether or not Tv) is higher than the third predetermined value (Tset3), and the compressor rotation speed control means determines that the determination result by the temperature determination means is "calculated temperature (Tv) of the inverter." The air conditioning according to any one of (1) to (4), wherein the number of revolutions of the compressor is reduced via the inverter and the electric motor when is higher than the third predetermined value (Tset3). apparatus.

【0016】

(6) Evaporator air flow control for reducing the air volume of the evaporator when the determination result by the temperature determination means is "the temperature (T) of the inverter is higher than the first predetermined value (Tset1)". The air conditioner according to any one of (1) to (5), further comprising means.

【0017】

(7) Expansion valve opening that increases the opening degree of the expansion valve when the determination result by the temperature determination means is "the temperature (T) of the inverter is higher than the first predetermined value (Tset1)". The air conditioner according to any one of (1) to (6), further comprising a temperature control means.

【0018】

(8) When the determination result by the temperature determination means is "the temperature (T) of the inverter is higher than the first predetermined value (Tset1)", the rotation speed of the capacitor fan attached to the capacitor is determined. The air conditioner according to any one of (1) to (7), further comprising a condenser fan speed control means for raising the condenser fan speed.

【0019】

(9) The air conditioner according to any one of (3) to (8), wherein the compressor rotation speed control means and the compressor rotation stop means are integrally configured with the inverter.

【0020】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the air conditioner according to the embodiment of the present invention will be described with reference to the drawings.

【0021】

[Embodiment 1] This air conditioner is mounted on a vehicle such as an automobile whose drive source is an internal combustion engine and / or an electric motor. With reference to FIG. 1, the air conditioner has an air conditioner unit 100 that forms an air passage to the passenger compartment of the vehicle. The air conditioning unit 100 is provided with an evaporator fan 25, which is a blower that generates an air flow toward the vehicle interior. The evaporator fan 25 is a well-known one including a fan motor and a fan. The air conditioning unit 100 on the upstream side of the evaporator fan 25 has an inside air introduction port 111 for taking in vehicle interior air (hereinafter referred to as inside air) and an outside air introduction port for taking in vehicle interior outside air (hereinafter referred to as outside air). 112 and are formed. These can be selectively opened and closed by the inside / outside air switching door 120. The inside / outside air switching door 120 is driven by a servomotor. Then, when the inside / outside air switching door 120 closes the inside air introduction port 111 and opens the outside air introduction port 112, the outside air mode is set. On the other hand, when the inside / outside air switching door 120 closes the outside air introduction port 112 and opens the inside air introduction port 111, the inside air mode is set.

【0022】

An evaporator 14 for cooling the passing air is housed and arranged in the air conditioning unit 100 on the downstream side of the evaporator fan 25. The evaporator 14 is a component of the refrigeration circuit 10.

【0023】

The refrigeration circuit 10 separates the vapor phase refrigerant and the liquid phase refrigerant from the compressor 11 that compresses the refrigerant to high temperature and high pressure, the condenser 12 that condenses and liquefies the high temperature and high pressure refrigerant, and the condensed liquefied refrigerant. It includes a receiver 24 for storing the liquid phase refrigerant, an expansion valve 13 for reducing the pressure of the liquid phase refrigerant, and an evaporator 14 for evaporating and vaporizing the reduced pressure refrigerant. These components are connected by a refrigerant pipe 15.

【0024】

The compressor 11 is driven by an electric motor 21. The rotation speed of the compressor 11 is controlled by continuously changing the input to the electric motor 21 by the inverter 22 according to the cooling load, whereby the air-conditioned space is air-conditioned. That is, as shown in FIG. 2, the inverter 22 constitutes the compressor rotation speed control means 221 which will be described in detail later. The inverter 22 also comprises the compressor rotation stopping means 222 and the inverter temperature detecting means 223, which will be described in detail later, as shown in FIG.

【0025】

A heater core 26, which is a superheater that superheats air that has passed through the evaporator 14, is arranged in the air conditioning unit 100 on the downstream side of the evaporator 14. The heater core 26 uses the cooling water of the vehicle drive source as a heat source. An air mix door 130 is provided on the air downstream side of the evaporator 14 and on the air upstream side of the heater core 26. The air mix door 130 adjusts the temperature of the conditioned air by adjusting the air volume ratio between the air that has passed through the evaporator 14 and the air that has passed through the heater core 26 and that is bypassed. The air mix door 130 is driven by, for example, a servomotor (not shown).

【0026】

As shown in FIGS. 1 and 2, in this example, the electric motor 21 is integrally configured with the compressor 11.

【0027】

Further, as shown in FIGS. 1 and 2, the inverter 22 and the electric motor 21 are provided so as to be interposed between the evaporator 14 and the compressor 11 in the refrigerating circuit 10, and are vaporized and vaporized by the evaporator 14. It is cooled by the refrigerant. The refrigerant that has cooled the inverter 22 and the electric motor 21 proceeds to the compressor 11 side.

【0028】

This air conditioner is controlled by the control unit 30. Hereinafter, the control unit 30 will be described.

【0029】

The control unit 30 is a well-known computer means such as RAM, ROM, and CPU, and performs air conditioning calculation processing based on various air conditioning information. Further, the control unit 30 is supplied with electric power from a battery mounted on the vehicle.

【0030】

The control unit 30 is provided as input terminals on an inside air sensor 351 that detects the temperature inside the vehicle interior in the air-conditioned space, an outside air sensor 352 that detects the temperature outside the vehicle interior, and an air conditioning operation panel (not shown) inside the vehicle interior. A temperature setter 355 that sets the set temperature in the room, a water temperature sensor 353 that detects the temperature of the cooling water of the vehicle drive source, and the temperature of the air that has passed through the evaporator 14 are detected immediately downstream of the evaporator 14. The outlet temperature sensor 354 is connected. Further, as is clear from FIGS. 1 and 2, the inverter temperature determining means 31 of the control unit 30 can read the temperature of the inverter 22 from the inverter temperature detecting means 223.

【0031】

As shown in FIG. 1, the control unit 30 is also connected to the fan motor of the evaporator fan 25 as an output terminal, and functions as the evaporator fan rotation speed control means 32. Specifically, the evaporator fan rotation speed control means 32 is a drive circuit composed of a variable resistor.

【0032】

The air conditioner has an inverter temperature determining means 31 in the control unit 30 for determining whether or not the temperature (T) of the inverter 22 obtained from the inverter temperature detecting means 223 is higher than the first predetermined value (Tset1). ing.

【0033】

Further, in this air conditioner, when the determination result by the inverter temperature determination means 31 is "the temperature (T) of the inverter 22 is higher than the first predetermined value (Tset1)", the inverter 22 and the electric motor 21 are used. It has a compressor rotation speed control means 221 that reduces the rotation speed of the compressor 11.

【0034】

The inverter temperature determining means 31 also determines whether or not the temperature (T) of the inverter 22 is higher than the second predetermined value (Tset2), which is higher than the first predetermined value (Tset1). The air conditioner also passes through the inverter 22 and the electric motor 21 when the determination result by the inverter temperature determining means 31 is "the temperature (T) of the inverter 22 is higher than the second predetermined value (Tset2)". Further, the compressor rotation stopping means 222 for stopping the compressor 11 is provided.

【0035】

The compressor rotation speed control means 221 is a compressor when the determination result by the inverter temperature determining means 31 at the time of starting the compressor 11 is "the temperature (T) of the inverter 22 is higher than the first predetermined value (Tset1)". After starting 11, the number of revolutions of the compressor 11 is kept lowered via the inverter 22 and the electric motor 21 until the temperature (T) of the inverter 22 becomes equal to or lower than the first predetermined value (Tset1).

【0036】

Further, the control unit 30 reduces the amount of air blown by the evaporator 14 when the determination result by the inverter temperature determining means 31 is "the temperature (T) of the inverter 22 is higher than the first predetermined value (Tset1)". The opening degree of the expansion valve 13 when the determination result by the evaporator fan rotation speed control means 32 and the inverter temperature determination means 31 is "the temperature (T) of the inverter 22 is higher than the first predetermined value (Tset1)". When the determination result by the expansion valve opening degree control means 33 and the inverter temperature determination means 31 is "the temperature (T) of the inverter 22 is higher than the first predetermined value (Tset1)", the capacitor 12 is used. It also has a condenser fan rotation speed control means 34 for increasing the rotation speed of the installed condenser fan 23.

【0037】

In this example, the compressor rotation speed control means 231 and the compressor rotation stop means 222 are integrally configured with the inverter 22. However, in the present invention, the compressor rotation speed control means 231 and the compressor rotation stop means 222 may be configured separately from the inverter 22, for example, integrally with the control unit 30.

【0038】

Next, the control contents of the control unit 30 will be described with reference to the flow charts shown in FIGS. 5 and 6. It should be noted that these flows are executed when a key switch of a vehicle (not shown) is turned on.

【0039】

First, referring to FIG. 5, in step S01, the detection value of the inside air sensor 351 and the detection value of the outside air sensor 352, the detection value of the water temperature sensor 353, the set temperature Tset0 of the temperature setter 355, and the blowout are used to read the air conditioning information. Read the detected temperature of the temperature sensor 354.

【0040】

In step S02, the target blowing temperature Teo of the blowing temperature of the air passing through the evaporator 14 is calculated based on the information read in step S01.

【0041】

Next, in step S03, the target rotation speed Nc of the compressor 11 is calculated from the target blowout temperature Teo calculated in step S20. The target rotation speed Nc is calculated so that the lower the target blowout temperature Teo, the higher the target rotation speed Nc. Further, the inverter 22 controls the input current value so as to have the target rotation speed Nc.

【0042】

Then, in step S04, the inside / outside air mode is determined, and specifically, the target blowing temperature Teo calculated in step S20 is set to be lower than the inside / outside air mote.

【0043】

In step S05, the opening degree of the air mix door 130 is determined, and the opening degree is determined according to the target blowing temperature Teo and the detection temperature of the water temperature sensor 353. If the target outlet temperature is Teo or very low, the air mix door 130 has an opening degree at which all the air that has passed through the evaporator 14 bypasses the heater core 26.

【0044】

Further, in step S06, the amount of air blown by the evaporator fan 25 (applied voltage Vn of the fan motor) is set, and this applied voltage is set so that the target blowing temperature Teo becomes lower and larger.

【0045】

Step S10 is a main part of the present embodiment, and reduces the rotation speed of the compressor 11 via the inverter 22 and the electric motor 21 according to the temperature (T) of the inverter 22 obtained from the inverter temperature detecting means 223. Etc. are controlled.

【0046】

This will be described below with reference to FIG.

【0047】

First, the inverter temperature determining means 31 of the control unit 30 detects the temperature (T) of the inverter 22 via the inverter temperature detecting means 223 (step S11), and the temperature (T) of the inverter 22 is the first predetermined value. It is determined whether or not it is higher than the value (Tset1) (step S12). If the result of the determination is "the temperature (T) of the inverter 22 is equal to or less than the first predetermined value (Tset1)", the process proceeds to step S13. On the other hand, if "the temperature (T) of the inverter 22 is higher than the first predetermined value (Tset1)", the process proceeds to step S15.

【0048】

In step S13, the control unit 30 sets the rotation speed of the compressor 11 to the target rotation speed Nc via the inverter 11 and the electric motor 21, and returns to step S11.

【0049】

In step S15, the compressor rotation speed control means 221 reduces the rotation speed of the compressor 11 via the electric motor 21 in accordance with the instruction from the control unit 30.

【0050】

In step S16, the inverter temperature determining means 31 detects the temperature (T) of the inverter 22 via the inverter temperature detecting means 223, and the temperature (T) of the inverter 22 is higher than the first predetermined value (Tset1). Judge whether or not. As a result of the determination, if "the temperature (T) of the inverter 22 is equal to or less than the first predetermined value (Tset1)", the process proceeds to step S13, while "the temperature (T) of the inverter 22 is still the first predetermined value". If it is higher than (Tset1), the process returns to step S15. If the temperature (T) of the inverter 22 is higher than the first predetermined value (Tset1) and the rotation speed of the compressor 11 is the minimum, the process proceeds to step S17.

【0051】

In step S17, the inverter temperature determining means 31 detects the temperature (T) of the inverter 22 via the inverter temperature detecting means 223, and the temperature (T) of the inverter 22 is higher than the second predetermined value (Tset2). Judging whether it is high or not. As a result of the judgment, "the temperature (T) of the inverter 22 is equal to or less than the second predetermined value (Tset2)", and "the temperature (T) of the inverter 22 is the first predetermined value". If it is "higher than (Tset1)", the process proceeds to step S18, while if "the temperature (T) of the inverter 22 is higher than the second predetermined value (Tset2)", the process proceeds to step S24. The compressor rotation stop means 222 of the inverter 22 stops the rotation of the compressor 11.

【0052】

In step S18, the evaporator fan rotation speed control means 32 of the control unit 30 reduces the amount of air blown by the evaporator 14.

【0053】

In step S19, the inverter temperature determining means 31 detects the temperature (T) of the inverter 22 via the inverter temperature detecting means 223, and the temperature (T) of the inverter 22 is higher than the first predetermined value (Tset1). It is determined whether or not the temperature is high. As a result of the determination, if "the temperature (T) of the inverter 22 is equal to or less than the first predetermined value (Tset1)", the process proceeds to step S13, while still "the temperature of the inverter 22 (T)". ) Is higher than the first predetermined value (Tset1) , the process proceeds to step S20.

【0054】

In step S20, the condenser fan rotation speed control means 34 of the control unit 30 increases the rotation speed of the condenser fan 23 attached to the condenser 12.

【0055】

In step S21, the inverter temperature determining means 31 detects the temperature (T) of the inverter 22 via the inverter temperature detecting means 223, and the temperature (T) of the inverter 22 is higher than the first predetermined value (Tset1). It is determined whether or not the temperature is high. As a result of the determination, if "the temperature (T) of the inverter 22 is equal to or less than the first predetermined value (Tset1)", the process proceeds to step S13, while still "the temperature of the inverter 22 (T)". ) Is higher than the first predetermined value (Tset1) , the process proceeds to step S22.

【0056】

In step S22, the expansion valve opening degree control means 33 of the control unit 30 increases the opening degree of the expansion valve 13.

【0057】

In step S23, the inverter temperature determining means 31 detects the temperature (T) of the inverter 22 via the inverter temperature detecting means 223, and the temperature (T) of the inverter 22 is higher than the first predetermined value (Tset1). It is determined whether or not the temperature is high. As a result of the determination, if "the temperature (T) of the inverter 22 is equal to or less than the first predetermined value (Tset1)", the process proceeds to step S13, while still "the temperature of the inverter 22 (T)". ) Is higher than the first predetermined value (Tset1) , the process proceeds to step S25, and the compressor rotation stopping means 222 of the inverter 22 stops the rotation of the compressor 11.

【0058】

[Variation Example of Control] In the present invention, in the compressor rotation speed control means 221, the determination result by the inverter temperature determination means 31 at the time of starting the compressor 11 is "the temperature (T) of the inverter 22 is the first predetermined value." When it is "higher than (Tset1)", after the compressor 11 is started, the rotation speed of the compressor 11 is increased until the temperature (T) of the inverter 22 becomes equal to or less than the first predetermined value (Tset1). May be left lowered via.

【0059】

[Other Modifications of Control] In the present invention, the compressor suction pressure detecting means 113 for detecting the suction pressure (Ps) of the compressor 11 may be provided.

【0060】

In this case, the control unit 30 can calculate the calculated temperature (Tv) of the inverter 22 according to the suction pressure (Ps) of the compressor 11. The inverter temperature determining means 31 also determines whether or not the calculated temperature (Tv) of the inverter 22 calculated according to the suction pressure (Ps) of the compressor 11 is higher than the third predetermined value (Tset3). The compressor rotation speed control means 221 determines the inverter 22 and the electric motor 21 when the determination result by the inverter temperature determination means 31 is "the calculated temperature (Tv) of the inverter 22 is higher than the second predetermined value (Tset2)". The rotation speed of the compressor 11 is reduced through.

【0061】

Next, the control contents of the control unit 30 will be described with reference to the flow chart shown in FIG.

【0062】

First, referring to FIG. 7, the control unit 30 detects the suction pressure (Ps) of the compressor 11 via the compressor suction pressure detecting means 112 (step S31), while the suction pressure (Ps) of the compressor 11 is detected. The calculated temperature (Tv) of the inverter 22 is calculated according to (step S35).

【0063】

In step S32, the control unit 30 determines whether or not the calculated temperature (Tv) of the inverter 22 is higher than the third predetermined value (Tset3). As a result of the determination, if "the calculated temperature (Tv) of the inverter 22 is equal to or less than the third predetermined value (Tset3)", the process proceeds to step S33, while "the calculated temperature (Tv) of the inverter 22 is the third predetermined value". If it is higher than the value (Tset3), the process proceeds to step S36.

【0064】

In step S33, the control unit 30 sets the rotation speed of the compressor 11 to the target rotation speed Nc via the inverter 11 and the electric motor 21, and returns to step S31.

【0065】

In step S36, the compressor rotation speed control means 221 reduces the rotation speed of the compressor 11 via the electric motor 21 in accordance with the instruction from the control unit 30.

【0066】

In step S37, the control unit 30 determines whether or not the calculated temperature (Tv) of the inverter 22 is higher than the third predetermined value (Tset3). As a result of the determination, if "the calculated temperature (Tv) of the inverter 22 is equal to or less than the third predetermined value (Tset3)", the process proceeds to step S33, while "the calculated temperature (Tv) of the inverter 22 is still the third". If it is higher than the predetermined value (Tset3), the process returns to step S36. If "the calculated temperature (Tv) of the inverter 22 is higher than the third predetermined value (Tset3)" and the rotation speed of the compressor 11 is the minimum, the process proceeds to step S38.

【0067】

In step S38, the compressor rotation stopping means 222 of the inverter 22 stops the rotation of the compressor 11.

【0068】

[Embodiment 2] In the present invention, as shown in FIGS. 3 and 4, the inverter 22 ́ may be integrally configured with the electric motor 21 ́. Further, the electric motor 21 ́ and the inverter 22 ́ may be integrally configured with the compressor 11.

【0069】

Since the air conditioner has the same configuration and the same control operation as in the first embodiment except that the inverter 22 ́ is integrally configured with the electric motor 21 ́, the description thereof will be omitted.

【0070】

In the embodiment described above, the refrigerating circuit 10 is dedicated to cooling, but the refrigerant is condensed and liquefied by the evaporator 14 by switching the flow direction of the refrigerant, and the air conditioning unit 100 is generated by the heat of condensation. It may be a heat pump type that heats the air inside. Further, the compressor 11 may be a fixed capacity type or a variable capacity type.

【0071】

Further, the present invention is not limited to vehicle air conditioners, but is also applicable to home and commercial air conditioners, for example.

【0072】

[Effect of the invention]

In the air conditioner according to the present invention, the temperature determination means for determining whether or not the temperature (T) of the inverter is higher than the first predetermined value (Tset1) and the determination result by the temperature determination means are "inverter temperature (T)". Is higher than the first predetermined value (Tset1) , the inverter has an excessive temperature of the inverter because it has a compressor rotation speed control means for lowering the rotation speed of the compressor via an inverter and an electric motor. By preventing the rise, damage to the inverter can be reliably avoided.

[Simple explanation of drawings]

[Figure 1]

It is an overall block diagram of the vehicle air conditioner according to Embodiment 1 of this invention.

[Figure 2]

It is a figure which shows the main part of the air conditioner shown in FIG.

[Fig. 3]

It is an overall block diagram of the vehicle air conditioner according to Embodiment 2 of this invention.

[Fig. 4]

It is a figure which shows the main part of the air conditioner shown in FIG.

[Fig. 5]

It is a flow chart which shows the basic air-conditioning control contents by the control part of the air-conditioning apparatus shown in FIG.

[Fig. 6]

It is a flow chart which shows the control content for the inverter protection by the air conditioner shown in FIG.

[Fig. 7]

It is a flow chart which shows the modification of the control content for protection of the inverter by the air conditioner by this invention.

[Explanation of symbols]

10 refrigeration circuit 11 Compressor 12 capacitors 13 Expansion valve 14 Evaporator 15 Refrigerant pipe 21, 21 ́ Electric motor 22, 22 ́ Inverter 23 condenser fan 24 receiver 25 Evaporator fan 30 Control unit 31 Inverter temperature determination means 32 Evaporator fan speed control means 33 Expansion valve opening control means 34 Condenser fan speed control means 100 air conditioning unit 113 Compressor suction pressure detecting means 221 Compressor speed control means 222 Compressor rotation stop means 223 Inverter temperature detection means