Air conditioning unit for motor vehicles and method for its operation

The present invention relates to an automobile air-conditioning unit provided with a compression refrigeration circuit (compression refrigerant circuit) and a method for operating the same.

Automotive air conditioning units typically include compressors, heat exchangers that release heat, ie condensers or gas coolers, expansion elements and one or several heat exchangers that absorb heat, such as evaporation. Have a vessel. The heat dissipation heat exchanger works to cool the refrigerant after it has been compressed and heated as close as possible to ambient temperature levels. The heat dissipation heat exchanger is typically housed in an engine chamber between the headlamps that are exposed to the air flow. If the air flow is inadequate, the function of the heat exchanger for heat dissipation is additionally assisted by one or several fans.

Traditional air conditioning units are usually passed through a refrigerant often composed of a composition containing fluorine. Such units are generally operated in subcritical mode. This means that if the refrigerant evaporates at a low temperature level and if the refrigerant condenses at a high temperature level, the two-phase region of the refrigerant will pass through. In addition, there are known air conditioning units whose circuits operate on the basis of natural refrigerants such as carbon dioxide. Refrigeration circuits that use carbon dioxide as the refrigerant generally operate in supercritical mode. This means that both the temperature and pressure in the state of the refrigerant obtained by compression are higher than the critical pressure and critical temperature of carbon dioxide. Therefore, no path is made into the wet saturated steam region during the release of heat by the refrigerant in the next gas cooler.

In particular, it is important that the refrigerating capacity of an automobile air-conditioning unit in a compression refrigeration circuit operated at a criticality limit achieves the lowest possible refrigerant temperature before the refrigerant is sent to the expansion unit. For this purpose, circuit designers typically try to bring the refrigerant temperature in the heat dissipation heat exchanger as close to the ambient temperature as possible.

In many vehicles, it is difficult to make such an approach to ambient temperature, especially when the vehicle is parked or under undesired ambient conditions. On the cooling air side, the input temperature of the cooling air may be significantly higher than the ambient temperature, for example, due to the heated state of the pavement surface or the backflow from the engine chamber. This undesired preheating of cooling air can actually be as high as 20-25 ° C. Further, the oil cooler and the air supply cooler arranged on the upstream side also contribute to this effect. Even if the temperature of the refrigerant drops to the temperature of this relatively hot cooling air (which is virtually impossible by mere heat transfer), the resulting cooling effect, and therefore the refrigerating capacity, is , Will often be inadequate. As a result, it is no longer possible to achieve optimum high pressure or required refrigeration capacity, respectively, depending on the circuit design. The result is a decrease in COP and an increase in the power demand for compressor drives. Especially in high ambient temperatures, where high refrigeration capacity is usually required, these effects work extremely negatively and become normal in the meantime, which is incompatible with the demand for comfort.

For example, it is known that the capacity of an automobile air-conditioning unit is enhanced by passing a refrigerant through a branched flow path using an internal heat exchanger that utilizes a separated flow provided on the upstream side of the evaporator (). International Publication No. 2005/059449 (A1) Pamphlet and German Patent Application Publication No. 10060114 (A1)). However, such designs impose relatively stringent installation requirements on the realization of various channels and many line connections.

In addition, it is known to cool the refrigerant before sending it to the condenser / gas cooler. This can be obtained because an additional heat exchanger is provided between the compressor of the air conditioning unit and the throttle device to extract heat from the compressed refrigerant before it reaches the condenser / gas cooler. Yes (German Patent Application Publication No. 10231645 (A1)). In this way, the inlet temperature on the high temperature side of the condenser / gas cooler is reduced. However, the problem that the ambient temperature is too high as the lowest theoretically achievable refrigerant temperature at the outlet of the heat dissipation heat exchanger remains unsolved in this solution.

In addition, a heat exchanger is placed in front of the evaporator, where the temperature of the refrigerant is reduced before it enters the evaporator by extracting heat from the refrigerant in countercurrent mode by evaporating water as a liquid. It is known. For this purpose, the water to be evaporated is drawn from the collected condensate of the air conditioning unit and sent to the heat exchanger (German Patent Application Publication No. 10159148 (A1)). This solution is disadvantageous because the efficiency of condensate formation and evaporation is strongly dependent on ambient conditions, especially the humidity of the air. Therefore, the support function of such an assembly can only be controlled within a narrow limit. In addition, this additional cooling function depends on the operating state of the air conditioning circuit. It is necessary to allow at least a certain operating time in advance until sufficient condensate flow begins to supply the condensate to the additional heat exchanger.

It is also known to be provided in the refrigeration circuit in a state where the cold store that provides the potential cooling capacity is continuously switched, especially when the refrigerating capacity of the evaporator is not sufficient or effective (German Patent No. 1). 10258618 (B3) specification). Such a system is preferably used for air-conditioning a stopped vehicle and helps to cool the passenger cabin before the actual air-conditioning unit compression circuit is fully effective.

<patcit num="1"><text>International Publication No. 2005/059449 (A1) Pamphlet</text></patcit><patcit num="2"><text>German Patent Application Publication No. 10060114 (A1)</text></patcit><patcit num="3"><text>German Patent Application Publication No. 10231645 (A1)</text></patcit><patcit num="4"><text>German Patent Application Publication No. 10159148 (A1)</text></patcit><patcit num="5"><text>German Patent No. 10258618 (B3)</text></patcit>

<p> An object of the present invention is to ensure sufficient refrigerating capacity of an automobile air conditioning unit for all vehicle operating conditions with as little effort as possible under critical conditions, such as when the vehicle is stopped and / or when the ambient temperature is high. There is.</p><p> This problem is solved by an air conditioning unit having the feature of claim 1. Claims 2 to 11 describe advantageous embodiments of the air conditioning unit of the present invention. Claim 12 relates to a method of operating the air conditioning unit of the present invention. Claims 13-17 describe advantageous embodiments of this method. An essential aspect of the present invention is to support the heat dissipation function of the compression refrigeration circuit of an automobile air conditioning unit. This assistance is achieved because an additional heat sink is inserted in the compression refrigeration circuit. Such a heat sink is added to the compression refrigeration circuit on the downstream side of the heat dissipation heat exchanger. The thermal properties of the heat sink are switchable and / or controllable. The function of the heat sink, that is, the function of removing heat from the refrigerant of the compression refrigeration circuit, is mainly executed in a state of being separated from the operating state of the compression refrigeration circuit. Overall, the present invention allows for effective and defined cooling of the refrigerant in the compression refrigeration circuit of the automotive air conditioning unit, which should be achieved as required. Thus, the gist of the present invention is an automobile air-conditioning unit provided with a compression / refrigeration circuit in which a refrigerant circulates, which is provided on the upstream side of a heat radiating heat exchanger and a heat absorbing heat exchanger, respectively, and allows a flow of fluid. From the outlet of the heat dissipation heat exchanger, with at least one compressor and expansion element that is continuously and extensively switched with respect to, with additional heat exchangers thermally coupled to at least one cooling means. It is incorporated in the flow path leading to the expansion element, and is characterized in that the temperature of the cooling means can be set to a temperature lower than the temperature of the refrigerant in the compression refrigeration circuit at the outflow position of the refrigerant from the heat dissipation heat exchanger. Located in the air conditioning unit. The present invention, on the one hand, is incorporated into the flow from the heat absorption heat exchanger to the compressor, and on the other hand, is incorporated into the flow path from the heat dissipation heat exchanger to the expansion element, and the heat sink of the present invention with respect to the flow of fluid. It can be advantageously utilized if additional internal heat exchangers are provided that can be switched in series with additional heat exchangers that act as.</p><p> The present invention is advantageously an automobile air conditioning unit provided with a compression refrigeration circuit in which a refrigerant circulates, which is provided on the upstream side of a heat radiating heat exchanger and a heat absorbing heat exchanger, respectively, and allows a flow of fluid. In a compression / refrigeration circuit that has at least one compressor and expansion element that can be continuously and extensively switched with respect to, especially in a compression refrigeration circuit that operates in an overcritical state, on the one hand a flow path leading from a heat absorption heat exchanger to the compressor An internal heat exchanger is further built in and, on the other hand, is built into the flow path leading from the heat dissipation heat exchanger to the expansion element, and an additional heat exchanger expands from the outlet of the heat dissipation heat exchanger. Incorporated in the flow path leading to the element, an additional heat exchanger is thermally coupled to the cooling means to bring the temperature of the cooling means to the refrigerant in the compression refrigeration circuit at the location of the refrigerant outflow from the heat dissipation heat exchanger. It is based on an air conditioning unit, which is characterized in that the temperature can be lower than the temperature of. The present invention can also be used for an air conditioning unit in which the refrigerant in the compression refrigeration circuit is composed of compressed carbon dioxide. The cooling means in the viewpoint of the present invention are technical media and devices that can or are required to reduce the temperature in particular. These are not limited to refrigerants and / or cooling fluids, but include them.</p><p> In order to operate the air-conditioning unit of the present invention, it is a method of operating the air-conditioning unit for automobiles including the above-mentioned components of the compression refrigeration circuit in which the refrigerant circulates, and the outflow of the refrigerant from the heat exchanger that releases heat to the surroundings. At least one parameter that depends on the temperature of the refrigerant at the location is measured or manually determined, and depending on the value of this parameter, downstream of the heat exchanger that releases heat to the surroundings with respect to the flow of fluid. A method characterized by reducing the temperature of at least one cooling means thermally coupled to the compression refrigeration circuit via an additional heat exchanger located upstream of the expansion element is suitable. To achieve this, the temperature of the refrigerant itself or the surface temperature of the line leading the refrigerant is measured as a parameter that depends on the temperature of the refrigerant at the outflow position of the refrigerant from the heat exchanger that releases heat to the surroundings. Is good. The manual operation of such parameters may be merely a confirmation that the temperature subjectively perceived in the driver's cab is too high.</p><p> The automatic operation of the air conditioning unit of the present invention can be carried out, for example, by automatically reducing the temperature of the refrigerant when the value of the measurement parameter exceeds the threshold value. It is particularly advantageous to lower the temperature of the refrigerant in a controlled manner and use the measurement parameters as control variables. This means that instead of simply booting additional heatsinks, the energy required to boot the heatsinks is not wasted by too high a cooling output, but is continuously used as required.</p>

<p> The realization of refrigeration output can be guaranteed under critical conditions for the heat dissipation heat exchanger, which is part of the compression refrigeration circuit of the automotive air conditioning unit. The improvement in customer comfort is obvious. The increase in the capacity of the compression refrigeration circuit can be switched automatically, easily or manually.</p><p> Environmental and economic benefits come with it. This is because the components of the compression refrigeration circuit of the air conditioning unit of the present invention can be more precisely sized to the rating due to the switchable power storage, yet under optimum ambient and normal ambient conditions. This is because less energy is required to operate the air conditioning unit underneath.</p><p> Expensive means of thermally optimizing the front part of the vehicle can be significantly reduced or eliminated altogether. A wide variety of vehicles are easily feasible. This is because the area of the major compression refrigeration circuit does not require individual optimization measures. The solution of the present invention can be applied to vehicles of various forms and vehicles of different manufacturers with relatively little effort. Also, retrofitting is possible, and with respect to fluid flow, the main compression refrigeration circuit of the air conditioning unit and the support unit that helps lower the temperature at the additional heat exchangers are consistently separated from each other. Therefore, retrofitting can be performed with a small amount of installation effort. All you have to do is incorporate an additional heat exchanger into the existing original compression refrigeration circuit. This is a great advantage in opening up the retrofit market.</p><p> Further, for the reasons described above, in the air conditioning unit of the present invention, an additional heat exchanger thermally coupled to at least one cooling means capable of lowering the temperature to a temperature lower than the ambient temperature is used as a heat exchanger for heat dissipation. It is advantageous to incorporate it into the flow path leading from the outlet to the internal heat exchanger. It is particularly advantageous if the temperature of the cooling means can be adjusted depending on the temperature of the refrigerant in the compression refrigeration circuit.</p><p> If the cooling means includes a secondary circuit that uses a circulating fluid and an additional heat exchanger for heat dissipation, the result is a particularly simple embodiment of the invention. Only the cooling power of the heat dissipation heat exchanger, which may already be useful in extreme operating conditions, is coupled into the main compression refrigeration circuit.</p><p> Alternatively or additionally, the advantage is obtained when the cooling means includes at least one thermoelectric element.</p><p> Alternatively or additionally, it would be advantageous if the main compression refrigeration circuit of the air conditioning unit could be thermally coupled to the cold part of the heat pump circuit via an additional heat exchanger.</p><p> Another advantageous embodiment of the air conditioning unit of the present invention is obtained if a cold store is provided downstream of the endothermic heat exchanger that can be charged by a charging heat exchanger positioned in the compression refrigeration circuit with respect to fluid flow. Be done. In an operating state where it is not necessary to lower the temperature of the cooling means, the cold store is charged using a charging heat exchanger thermally coupled to the compression refrigeration circuit. In operating conditions where the temperature of the cooling means needs to be lowered, the cold store is thermally coupled to the compression refrigeration circuit via an additional heat exchanger. In this way, in these operating conditions, additional heat sinks of the present invention are provided. Thermal coupling of the cold store to the compression refrigeration circuit via an additional heat exchanger is favorably implemented by the secondary refrigeration circuit, which in this case is air-conditioned with the cold store by circulating fluid. Achieve thermal contact with the unit's main compression refrigeration circuit.</p><p> The same various embodiments of the cooling means embodiments in view of the present invention may be combined or interchanged with each other based on technical and / or economic conditions, and if necessary, technically and / or (or). ) Each may be tolerated based on economic conditions.</p>

The present invention will be described with reference to various examples of embodiments.

FIG. 1 shows a conventional compression refrigeration circuit for an automobile air conditioning unit. This circuit has a compressor 1, a heat exchanger for heat dissipation 2, that is, a heat exchanger in the form of a condenser or gas cooler, an expansion element 3 and an endothermic heat exchanger 4 in the form of, for example, an evaporator. There is. During the operation of the air conditioning unit, the refrigerant circulates in the compression refrigeration circuit, and the refrigerant continuously changes its temperature and / or pressure, resulting in a phase transition. A refrigerant is passed through the heat absorption heat exchanger 4 at a low pressure, and the refrigerant absorbs heat from the surrounding air to be cooled at that time. The absorption of heat causes evaporation and / or heating of the refrigerant. Next, the refrigerant as a gas is passed through the compressor 1, whereby the pressure and temperature of the refrigerant rise. A high-temperature refrigerant in a compressed state is directed to the heat exchanger 2 for heat dissipation, where a part of the heat energy is released to the ambient air, and the enthalpy of the compressed refrigerant is reduced. The compressed refrigerant is then directed toward the expansion element 3 to expand, resulting in a decrease in pressure and temperature thereof. At this stage, the expanded low-temperature refrigerant is led into the endothermic heat exchanger 4 again. In order to increase the efficiency of such an air conditioning unit, an internal heat exchanger 5 is preferably incorporated in a state where a countercurrent path is performed. For an air conditioning unit configured similar to an efficiently operating air conditioning unit, the refrigerant needs to be guided into the endothermic heat exchanger with the lowest enthalpy possible. Under desirable environments or operating conditions, the heat released by the heat dissipation heat exchanger 2 can ensure a sufficiently low refrigerant enthalpy at the outlet of the expansion element 3 under certain operating pressure conditions. Insufficient. In addition, accumulator 6 is shown for perfection. Also, the accumulator 6 should be combined with the internal heat exchanger 5 to form a component. Air is directed to both heat exchangers 2 and 4 as indicated by the arrows. One arrow indicates the airflow 7 to be cooled. The other arrow indicates the ambient airflow 8 that should draw heat from the heat dissipation heat exchanger 2 and cause cooling or condensation of the refrigerant.

FIG. 2 shows a compression refrigeration circuit of an automobile air-conditioning unit provided with an additional heat exchanger 9 that is continuously switched downstream of the heat dissipation heat exchanger 2 and upstream of the expansion element. The additional heat exchanger 9 is thermally coupled to a switchable heat sink, and its action as a heat sink is evident by the heat flow 10 directed away from the compression refrigeration circuit of the air conditioning unit.

FIG. 2 outlines the basic method of the solution of the present invention. The purpose is to extract a large amount of heat when heat is required, that is, when the cooling output of the heat dissipation heat exchanger 2 is too low. This function is provided by an additional heat exchanger 9 when needed. According to the present invention, this function is performed immediately downstream of the heat dissipation heat exchanger 2 before the refrigerant enters the internal heat exchanger 5. The requirement for an additional reduction in the temperature of the refrigerant is, for example, by measuring the temperature of the refrigerant after the refrigerant exits the heat dissipation heat exchanger 2, in some cases the temperature difference between the temperature of the refrigerant and the ambient temperature. May be found by judging. The controller should then make the decision to operate the additional heat exchanger 9. In this case, the heat sink on the secondary side of the additional heat exchanger 9 must be activated.

According to the present invention, such a heat sink on the secondary side of the additional heat exchanger 9 can be realized in various ways.

FIG. 3 shows a compression refrigeration circuit for an automotive air conditioning unit of the present invention with an additional heat exchanger 9 coupled to a secondary cooling circuit 11. In this simple embodiment of the invention, the additional heat exchanger 9 absorbs heat from the refrigerant on its primary side 9'and dissipates this heat to the secondary circuit 11 on its secondary side 9'. .. The secondary circuit 11 can send the absorbed heat to the surroundings via another heat exchanger 12, and the position of this other heat exchanger 12 can be freely selected. The functional principle of this embodiment is that, first of all, two heat exchangers 2 and 12 for heat dissipation are provided, and the position of these heat exchangers for heat dissipation is such that the heat dissipation efficiency to the ambient air is the actual boundary condition. It is based on making it progressively dependent. When the air flow is sufficient, the thermally non-deteriorated ambient air reaches the heat exchanger 2 for heat dissipation in the vapor-compression refrigeration circuit, resulting in efficient heat transfer. If the airflow is reduced (this may occur when the vehicle is decelerating or stopping), the temperature of the inflow air is close to the hot assembly in the engine compartment or the sidewalk where the temperature may be rising. In addition, it is no longer equal to the external temperature, and is partially much higher than this. This problem is sufficient for the assembly where the heat exchanger 12 is in a heated state and / or in some cases the sidewalk in a heated state and / or in some cases the area silenced by the stagnation of the flow. If the distance is secured, it will not occur in the heat exchanger 12 for heat dissipation of the secondary cooling circuit 11. In this case, a more preferred boundary condition for heat release exists at the heat exchanger 12 of the secondary cooling circuit 11. According to the present invention, the built-in coupling of the heat radiating heat exchanger 12 is a heat sink according to the present invention in which the recirculation of the cooling fluid in the secondary cooling circuit 11 requires energy to operate the secondary cooling circuit 11. When initiated by a switchable recirculator 13, preferably a recirculation pump, corresponding to the activation of the heat sink at the additional heat exchanger 9, by occurring only when it is necessary to be switchable. It is good to be implemented.

According to this embodiment of the present invention, the ambient temperature of the refrigerant can be reached as the minimum temperature. However, during actual operation, it is never possible to cool the refrigerant until it has an ambient temperature. This is because it is only possible to achieve limited component dimensions, and heat transfer requires a driving temperature difference.

FIG. 4 shows a compression refrigeration circuit of an automobile air conditioning unit of the present invention provided with an additional heat exchanger 9 in contact with a thermoelectric element 14 used as a cooling element. Thus, a preferred embodiment is configured in which the refrigerant can be cooled even to a temperature lower than the ambient temperature.

The work of thermoelectric elements is based on the Seebeck effect. When a voltage is applied to a thermoelectric element, regions of different temperatures are created. This physical effect can produce a cold portion directly from the current. The element acts like an electrically driven unit that produces a low temperature. A thermoelectric element absorbs heat at a particular temperature and releases this heat to the surroundings at a higher temperature level. According to the present invention, an additional heat exchanger 9 is brought into contact with the low temperature region 15 of the thermoelectric element 14. The high temperature region 16 of the thermoelectric element 14 is positioned so that it can dissipate heat to the ambient air. Therefore, the high temperature region 16 of the thermoelectric element 14 has a temperature close to the ambient temperature. When a voltage is applied, the temperature of the low temperature region 15 of the thermoelectric element 14 decreases accordingly. Thus, the cold region 15 of the thermoelectric element 14 produces a heat sink that can be used according to the present invention for further cooling the refrigerant in the compression refrigeration circuit after the refrigerant exits the heat exchanger 2. Similarly, embodiments of the present invention can be realized with some thermoelectric elements provided. Further, the thermoelectric element can cool the refrigerant to a temperature lower than the ambient temperature. However, operating a thermoelectric element requires electrical energy available from the vehicle-mounted power source of the vehicle. At the same time, the ability to switch electrical energy also allows the heat sink to be turned on in a manner similar to that required in a compression refrigeration circuit of an air conditioning unit, according to the present invention. This embodiment provides, among other things, the advantage of easy retrofitting. For example, a thermoelectric element can be easily retrofitted because it is attached to the refrigerant-containing portion of a tube or similar thermally conductive component and, when controlled accordingly, enhances heat dissipation to the surroundings. can do. Such a retrofit is advantageous, for example, when some percentage of the vehicle should be adapted to critical ambient conditions, for example, in a situation where the continuous production of the models involved is forced to change. Not surprisingly, the entire model series or mass production

FIG. 5 shows a compression refrigeration circuit for an automotive air conditioning unit of the present invention, which includes additional heat exchangers 9 , 9 coupled to another compression refrigeration circuit 17. .. This embodiment can also reduce the temperature of the refrigerant in the main compression refrigeration circuit of the air conditioning unit to a temperature lower than the ambient temperature after the refrigerant has been discharged from the heat dissipation heat exchanger 2. However, this separate vapor refrigeration circuit 17 is an additional circuit that is completely disconnected from the main vapor refrigeration circuit of the air conditioning unit with respect to fluid flow. An important component of this other compression / refrigeration circuit 17 is the compressor 18, expansion element, in addition to the secondary side 9 of the heat exchanger as a means of coupling the air conditioning unit to the main compression / refrigeration circuit. 19 and another heat exchanger 20 for heat dissipation, and the heat energy is dissipated toward the surroundings by the other heat exchanger 20 for heat dissipation. In a preferred embodiment, the compressor 18 is electrically driven. At the same time, the switchability of the compressor 18 also makes it possible to switch between additional heat sinks as required by the compression refrigeration circuit of the air conditioning unit, according to the present invention.

FIG. 6 also includes additional heat exchangers 9 , 9 coupled to a secondary cooling circuit 21 thermally coupled to the cold store 23 by another heat exchanger 22. The compression refrigeration circuit of the automobile air-conditioning unit of the present invention is shown. The cold store is preferably designed as a high volume fluid circuit with at least one recirculation element 24 realized as a pump. At the same time, in this advantageous embodiment of the air conditioning unit of the present invention, the cold store 23 is thermally directly coupled to the main compression refrigeration circuit of the air conditioning unit via the charging heat exchanger 25 for charging. The heat exchanger 25 is positioned downstream of the heat absorption heat exchanger 4 in the main vapor-compression refrigeration circuit with respect to the flow of fluid. In the operating state where it is not necessary to lower the temperature of the cooling means, the cold store 23 is charged via the charging heat exchanger 25 thermally coupled to the compression refrigeration circuit. In operating conditions where the temperature of the cooling means needs to be reduced, the cold store 23 is thermally coupled to the compression refrigeration circuit via additional heat exchangers 9 , 9 . In this way, in these operating conditions, additional heat sinks of the present invention are provided. Thermal coupling of the cold store 23 to the compression refrigeration circuit via additional heat exchangers 9, 9'is preferably achieved by the secondary cooling circuit 21, in which case such secondary cooling circuit In this case, the circulating fluid achieves thermal contact between the cold store 23 and the main compression refrigeration circuit of the air conditioning unit.

In this embodiment, the compression refrigeration process can be optimally performed in the compression refrigeration circuit without using the additional heat sink of the present invention, and the heat release conditions by the heat dissipation heat exchanger 2 are almost optimal or at least favorable. Charge the cold store 23 at. As a result, the refrigerant passes through another heat exchanger, that is, the charge heat exchanger 25, on the downstream side of the endothermic heat exchanger 4. If the heat absorption heat exchanger 4 is an evaporator, the refrigerant simply continues to evaporate within the charging heat exchanger 25, thereby the working medium on the secondary side of the charging heat exchanger 25, i.e. cold. Extract the corresponding amount of heat from the fluid in store 23. Therefore, the working medium thus cooled in the cold store 23 can absorb an equivalent amount of heat from the secondary cooling circuit 21 if necessary and is the basis of the "charged" cold store. .. The process described above is preferably carried out cyclically.

FIG. 7 shows a compression refrigeration circuit of an automotive air conditioning unit of the present invention with an alternative heat exchanger 9 in contact with a thermoelectric element 14. Compared to the embodiment of FIG. 4, the order of the internal heat exchanger 5 and the additional heat exchanger 9 has been changed in the flow direction. In other respects, the description in Figure 5 applies.

FIG. 8 shows a vapor-compression refrigeration circuit for an automobile air-conditioning unit of the present invention, in which the air-conditioning unit is an alternative positioned additional heat exchanger 9', 9 coupled to another vapor-compression refrigeration circuit 17. It has . Compared to the embodiment of FIG. 5, the order of the internal heat exchanger 5 and the additional heat exchangers 9 , 9 has been changed in the flow direction. In other respects, the description in Figure 5 applies.

<figref num="1">It is a figure which shows the traditional compression refrigeration circuit of the air-conditioning unit for a vehicle.</figref><figref num="2">It is a figure which shows the compression refrigeration circuit of the air-conditioning unit for automobiles of this invention which has the additional heat exchanger which is continuously switched on the downstream side of the heat exchanger for heat dissipation and the upstream side of an expansion unit.</figref><figref num="3">It is a figure which shows the compression refrigeration circuit of the heat exchange unit for automobiles of this invention which has an additional heat exchanger coupled to the secondary cooling circuit.</figref><figref num="4">It is a figure which shows the compression refrigerating circuit of the air-conditioning unit for automobiles of this invention which has an additional heat exchanger in contact with a thermoelectric cooling element.</figref><figref num="5">It is a figure which shows the compression refrigeration circuit of the air-conditioning unit for automobiles of this invention, and is the figure which shows the state which has the additional heat exchanger coupled to another compression refrigeration circuit.</figref><figref num="6">It is a figure which shows the compression refrigeration circuit of the air-conditioning unit for automobiles of this invention which has an additional heat exchanger coupled to the secondary cooling circuit which provided with a cold store.</figref><figref num="7">It is a figure which shows the compression refrigeration circuit of the air-conditioning unit for automobiles of this invention which has the additional heat exchangers arranged alternately in contact with a thermoelectric cooling element.</figref><figref num="8">It is a figure which shows the compression refrigeration circuit of the air-conditioning unit for automobiles of this invention, and is the figure which shows the state which has the additional heat exchanger coupled to the compression refrigeration circuit in the state which is alternately located in another compression refrigeration circuit. ..</figref>

Code description

1 compressor 2 Heat exchanger for heat dissipation 3 expansion element 4 Endothermic heat exchanger 5 Internal heat exchanger 6 accumulator 7 Cooled air flow 8 Ambient air flow 9 Additional heat exchanger 9'Primary side of additional heat exchanger 9 Secondary side of additional heat exchanger 10 heat flow 11 Secondary cooling circuit 12 heat exchanger 13 Recirculation factor 14 Thermoelectric element 15 Cold side of thermoelectric element 16 High temperature side of thermoelectric element 17 Another compression / refrigeration circuit 18 compressor 19 Expansion element 20 Heat exchanger for heat dissipation 21 Secondary cooling circuit 22 heat exchanger 23 Cold store 24 Recirculation factor 25 Charge heat exchanger