JPH11115466A - Air conditioner for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect an electric system from intrusion of a foreign matter, to prevent an increase of ventilation resistance and to save electric power by providing an auxiliary heat source in an air-conditioning passage in an electric vehicle. SOLUTION: An evaporator 8 and a subcondenser 9 are arranged in an air- conditioning passage, and a refrigerant circulation cycle including a compressor 17, the subcondenser 9, an expansion valve 16, and the evaporator 8 and a hot water circulation cycle including a hot water heating device 27 arranged outdoors and a hot water heater 25 which is provided on a downstream side of the subconderder 9 and circulates hot water heated by the hot water heating device 27 are provided. When air temperature in an inlet of the evaporator 8 is lower than a predetermined temperature, only the hot water circulation cycle is operated. When air temperature in the inlet of the evaporator 8 is higher than the predetermined temperature and a temperature in a compartment is lower than a target temperature, the hot water circulation cycle and the refrigerant circulation cycle are operated. When a temperature in the compartment is above the target temperature, only the refrigerant circulation cycle is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a first heat exchanger disposed between a discharge side of a compressor and an inflow side of an expansion device, and a first heat exchanger disposed between an outflow side of the expansion device and a suction side of the compressor. The present invention relates to an air conditioner for an electric vehicle, in which a second heat exchanger is disposed in an air conditioning passage, and a third heat exchanger is disposed downstream of the first heat exchanger as an auxiliary heat source. .

[0002]

2. Description of the Related Art A heat pump type air conditioner disclosed in Japanese Patent Application Laid-Open No. Hei 5-229333 has a first air conditioner in an air conditioning duct.
A heat exchanger (sub-condenser) of the vehicle interior and a second heat exchanger (evaporator) of the vehicle interior disposed upstream of the heat exchanger are provided on the inflow side of the heat exchanger (main condenser) outside the vehicle. The flow path switching means (three-way valve) allows the refrigerant flowing out of the compressor to be supplied to the exterior heat exchanger (main condenser) or to be bypassed. During the cooling operation, the exterior heat exchanger, A first compartment heat exchanger, an expansion valve, a second compartment heat exchanger,
The refrigerant is circulated in the order of the compressor, and during the heating operation, the refrigerant is circulated in the order of the first interior heat exchanger, the expansion valve, the second interior heat exchanger, and the compressor by bypassing the exterior heat exchanger. I try to make it.

[0003] Such an air conditioner uses the first vehicle interior heat exchanger as a radiator, uses the second vehicle interior heat exchanger as a heat absorber, and uses the air flowing through the air conditioning duct during the heating operation. The second compartment heat exchanger cools and dehumidifies and simultaneously heats the first compartment heat exchanger. When the outside air temperature is lower than 0 ° C. and the outside air temperature is low, the efficiency deteriorates. It has been pointed out that a sufficient heating capacity cannot be obtained with only the exchanger. Therefore, as one of the countermeasures, providing an auxiliary heat source in an air conditioning passage is being studied.

The provision of an auxiliary heat source in an air-conditioning passage is known as disclosed in Japanese Patent Application Laid-Open No. 7-223429, which discloses that a heat pump is provided in a ventilation circuit provided in a vehicle cabin. Two interior heat exchangers are provided, and an electric heater is provided further downstream than the downstream interior heat exchanger. From the viewpoint of saving space, this electric heater is integrated with the downstream heat exchanger. The configuration points are shown. In addition, since the electric heater uses a high voltage, it is dangerous if the electric heater is disposed in the vehicle interior. Therefore, the electric heater branches from the rear side of the heat exchanger on the upstream side to the outside of the vehicle interior, and merges again into the ventilation circuit in the vehicle interior. Is shown, and a downstream heat exchanger and an electric heater are arranged in the second ventilation circuit.

[0005]

However, the configuration of the auxiliary heat source as described above has a risk of electric shock due to electric leakage or foreign matter adhering to the electric heater to short-circuit the electric system of the electric heater. In the case of electric vehicles such as automobiles, all power is supplied by electricity, so we want to eliminate the scandal of the electric system as much as possible and give priority to safety.

In consideration of safety, a passage protruding outside the vehicle cabin is provided as in the above-mentioned prior art, and an electric heater is disposed in this passage. Although the merit is recognized, even with such a configuration, it is not possible to avoid a point where foreign matter entering the passage adheres to the electric heater and short-circuits, and also, the air introduced into the room is temporarily moved out of the vehicle compartment. After being guided and heated, it must be returned to the vehicle interior again, which complicates the ventilation path and increases the passage resistance.

[0007] In addition, from the demand to enable the electric vehicle to be used for a long time, it is necessary to perform heating control by combining the refrigerant circulation cycle and the auxiliary heat source as efficiently as possible to effectively use electric power. It is desirable to save space as in the conventional case.

Therefore, in the present invention, an electric vehicle is provided with an auxiliary heat source for improving the heating capacity in low outside air, but also protects the electric system and prevents an increase in ventilation resistance due to the entry of foreign matter. It is an object of the present invention to provide an electric vehicle air conditioner that can satisfy a demand for power saving. Another challenge is to reduce space requirements.

[0009]

To achieve the above object, an air conditioner for an electric vehicle according to the present invention comprises a compressor, a first heat exchanger provided on a discharge side of the compressor, and a first heat exchanger. A refrigerant circulation cycle including an expansion device that decompresses the refrigerant that has passed through the heat exchanger, and a second heat exchanger provided between an outflow side of the expansion device and an inflow side of the compressor. A fluid heating device for arranging the second heat exchanger and the first heat exchanger in this order from an upstream side in an air conditioning passage provided in the vehicle, and arranged outside the vehicle compartment to heat a fluid; A third heat exchanger that is provided downstream of the first heat exchanger in the passage and circulates a fluid heated by the fluid heating device; and an inlet air temperature of the second heat exchanger. Is lower than the first temperature. The second heat exchanger is operated when the inlet air temperature of the second heat exchanger is equal to or higher than the first temperature and the vehicle interior temperature is lower than the second temperature. The invention is characterized in that the compressor and the fluid heating device are operated, and when the vehicle interior temperature is equal to or higher than the second temperature, the compressor is operated to stop the fluid heating device (claim 1).

Here, the refrigerant circulation cycle includes a path between the compressor and the first heat exchanger that passes through the external heat exchanger and a path that bypasses the external heat exchanger. The refrigerant may be circulated only through the path that bypasses the exchanger (claim 2).

Therefore, according to the heating by the refrigerant circulation cycle, the high-temperature and high-pressure refrigerant pressurized by the compressor is guided to the first heat exchanger, where it is radiated, then decompressed by the expansion device and decompressed by the expansion device. And heat is absorbed by this second heat exchanger and then returned to the compressor. Therefore, the air introduced into the air conditioning passage is dehumidified by the second heat exchanger, and then heated by the first heat exchanger and sent downstream.

As described above, when the outside air is low, the heating capacity of the first heat exchanger may not be sufficiently obtained in some cases. However, the third heat exchanger using hot water as a heat source is replaced with the first heat exchanger. Since it is arranged on the downstream side, the air can be heated by the third heat exchanger, and sufficient warm air is blown into the vehicle compartment even in low outside air that cannot be handled by the first heat exchanger. be able to.

[0013] The third heat exchanger itself has no electric system, and uses hot water heated by a fluid heating device arranged outside the vehicle compartment as a heat source, so that foreign matter adheres to this heat exchanger. Even in this case, there is no danger of short-circuiting of the electric system, and there is no danger of electric shock due to electric leakage.

Further, if the inlet air temperature of the second heat exchanger is lower than the first temperature and the heating capacity in the refrigerant circulation cycle cannot be sufficiently obtained, the refrigerant circulation cycle may be operated. In this case, the compressor is stopped and heating is not performed by the refrigerant circulation cycle, and only the third heat exchanger is used to heat the air introduced into the air-conditioning passage because power is wasted. It is.

In the case where the inlet air temperature of the second heat exchanger is a temperature at which the heating control in the refrigerant circulation cycle can be sufficiently performed, immediate warming is required because the temperature in the vehicle compartment is low (see the second embodiment). (2) when the inlet air temperature of the heat exchanger 2 is equal to or higher than the first temperature and the vehicle interior temperature is lower than the second temperature)
When the compressor is operated and the fluid heating device is also operated, the introduced air is heated by the first heat exchanger and the third heat exchanger, and is supplied to the passenger compartment in a sufficiently warmed state.

When the vehicle interior temperature exceeds the second temperature beyond the area requiring immediate warming, normal air-conditioning control by the refrigerant circulation cycle is sufficient thereafter. The power supply to the device is stopped, and heating is continued only by the refrigerant circulation cycle, thereby eliminating waste of power.

[0017] Therefore, a request for heating at the time of low outside air, an immediate warming property,
From the viewpoint of power saving, the auxiliary heat source can be operated most efficiently in relation to the refrigerant circulation cycle.

Further, even in the above-described configuration, the third heat exchanger may be formed integrally with the first heat exchanger for the purpose of saving space as in the prior art (claim). Item 3).

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an air conditioner for an electric vehicle mounted on an electric vehicle such as an electric vehicle. In this air conditioner, an intake device 3 is provided on the most upstream side of an air conditioning duct 2 forming an air conditioning passage 1, The opening ratio between the inlet 4 and the outside air inlet 5 is adjusted by the intake door 6. The air sucked by the rotation of the blower 7 through the intake device 3 is supplied to the evaporator 8.
And to the sub-condenser 9, where the heat is exchanged.

The sub-condenser 9 is disposed downstream of the evaporator 8 so that the ratio of the air passing therethrough to the bypassing air can be varied by adjusting the opening of the air mixing door 10. . The sub-condenser 9 corresponds to the first heat exchanger, and the evaporator 8 corresponds to the second heat exchanger.

The most downstream side of the air conditioning duct 2 is divided into a defrost air outlet 11, a vent air outlet 12, and a heat air outlet 13 and opens into the vehicle compartment. The blowout mode is switched by operating the mode door.

The outflow side of the sub-condenser 9 is connected to the inflow side of the evaporator 8 via a liquid tank 15 and an expansion valve 16, and the outflow side of the evaporator 8 is connected to the suction side of the compressor 17 by piping. The discharge side of the compressor 17 is connected via a solenoid valve 18 to the inflow side of a main condenser 19.
The outflow side of 9 is connected to the inflow side of the sub-condenser 9 via a check valve 20. Further, a bypass passage 22 that is opened and closed by an electromagnetic valve 21 and bypasses the main condenser 19 is connected between the discharge side of the compressor 17 and the outflow side of the check valve 20.

Therefore, by controlling the opening and closing of the solenoid valves 18 and 21, the refrigerant discharged from the compressor 17 is transferred to the main condenser 19, the check valve 20, the sub-condenser 9, the liquid tank 15, the expansion valve 16 and the evaporator 8 in this order. A first cycle path for returning to the compressor 17 and a second cycle for bypassing the main condenser 19 to the sub-condenser 9, the liquid tank 15, the expansion valve 16 and the evaporator 8 and returning to the compressor 17 in this order. A cycle path can be selectively switched.

In the cooling control by such a refrigerant circulation cycle (heat pump), the electromagnetic valve 18 is opened, the electromagnetic valve 21 is closed, and the refrigerant flows through the first cycle path. Then, the refrigerant discharged from the compressor 17 is radiated by the main condenser 19 and supplied to the sub-condenser 9 through the check valve 20. Air mix door 10
Is located at a position where the amount of ventilation to the sub-condenser 9 is to be suppressed during cooling control. The sub-condenser 9 does not have much heat radiation and is sent to the liquid tank 15 as it is.
Thereafter, the pressure is reduced by the expansion valve 16 and enters the evaporator 8, where the heat is absorbed from the air in the air-conditioning duct 2 passing through the evaporator 8 and then returned to the compressor 17. Therefore, the air sucked into the air conditioning duct 2 by the driving of the blower 7 is cooled by the evaporator 8, and most of the air is supplied to the passenger compartment without passing through the sub-condenser 9, thereby cooling the passenger compartment.

On the other hand, in the heating control, the solenoid valve 18 is closed, the solenoid valve 21 is opened, and the refrigerant flows through the second cycle path. In such an operation mode, the air mixing door 10 is located at a position where the amount of air flowing into the sub-condenser 9 is large. In particular, when the vehicle interior temperature is extremely low or when immediate heating is required, the sub-condenser 9 Ventilation volume to the maximum. Then, the refrigerant discharged from the compressor 17 enters the sub-condenser 9 through the bypass passage 22 without passing through the main condenser 19, radiates heat here, and then enters the liquid tank 15. Thereafter, the pressure is reduced by the expansion valve 16 and enters the evaporator 8, where heat is absorbed from the air passing through the evaporator 8 and then returned to the compressor 17. The balance between the amount of heat absorbed by the evaporator 8 and the amount of heat radiated by the sub-condenser 9 is such that the air radiated into the air conditioning duct 2 is cooled and dehumidified by the evaporator 8 because the amount of heat radiated is large by the work of the compressor 17. The air is heated by the sub-condenser 9 more than it is cooled by the evaporator 8, and is supplied to the vehicle interior as warm air as a whole.

Downstream of the sub-condenser 9, a hot water heater 25 constituting a third heat exchanger is further arranged. The hot water heater 25 heats the passing air using the hot water as a heat source. A pipe for flowing the hot water is drawn out through a partition wall 26 that partitions the inside and outside of the vehicle interior, and is connected to a hot water heating device 27 arranged outside the vehicle interior. Have been. The hot water heating device 27 circulates hot water heated by an electric heater 28 such as a sheath type heater to a hot water heater 25 by a pump 29. The hot water heater 25 is turned on only when the electric heater 28 and the pump 29 are energized. When the electric power to the electric heater 28 and the pump 29 is stopped, the heating operation by the hot water heater 25 is stopped.

The hot water heater 25 in such a hot water circulation cycle is formed integrally with the sub-condenser 9, and the specific configuration is shown in FIGS. 2 (a) and 2 (b). In this example, both the sub-condenser 9 and the hot water heater 25 have a pair of tank portions 9a, 9b, 25a, 25b, a number of flat tubes 9c, 25c communicating between these tank portions, and a corrugated shape interposed between the flat tubes. And the fins 30 of the tanks 9a, 9
The b, 25a, 25b and the fin 30 are integrally formed by both heat exchangers. In other words, the tank section of each heat exchanger divides the inside of one tank block 31 into partition walls 3.
The tubes 9c and 25c are separately formed by respective heat exchangers and are inserted and joined to the tank block 31 so as not to cover the partition walls 32. . The fins 30 are provided between the tubes of one heat exchanger and between the tubes of the other heat exchanger.

In place of such a configuration, as shown in FIG. 3A, the tubes of the respective heat exchangers may be formed by integral tubes 33. That is, tube 3
3 is divided into two passages 35 and 36 with a rib 34 provided inside as shown in FIG. 3 (b), and the rib 34 and a partition wall 32 provided in the tank block 30 are abutted to form a tube 33. The passage 35 may be joined to the tank block 31, and one passage 35 may be used for the sub-condenser 9 and the other passage 36 may be used for the hot water heater 25. According to such a configuration, the width of the tank block 31 in the ventilation direction can be reduced by an amount corresponding to the tube being integrally formed, and further downsizing can be achieved.

Reference numeral 39 denotes a heat storage tank which stores the heat of the hot water heated by the hot water heating device 27,
In the case where the air conditioner is temporarily stopped and restarted, hot water having a high temperature can be used from the initial stage, thereby improving the immediate warming.

A duct temperature sensor 40 is provided upstream of the evaporator 8 and measures the temperature of the inlet air passing through the evaporator 8. During the heating operation, the intake device 3 is set to the outside air introduction mode. If it is set, it actually detects the outside air temperature, and if it is set to the inside air introduction mode,
The temperature of the cabin is detected substantially. In addition, 41
The sensor is a room temperature sensor for detecting a vehicle interior temperature, and detection signals from the temperature sensors 40 and 41 are input to the control unit 42 together with signals from other sensors and a setting signal from a manual setting unit (not shown).

The control unit 42 includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), an input / output port (I / O) and the like (not shown), and drives the compressor 17. It has an inverter, a drive circuit for controlling on / off of the solenoid valves 18 and 21, on / off of energization of the electric heater 28, and on / off of the pump 29, and various input signals according to a predetermined program given to the ROM. And drives and controls a compressor, a solenoid valve, an electric heater, a pump, and the like.

FIG. 4 is a flowchart showing an operation example of the refrigerant circulation cycle and the hot water circulation cycle at the time of heating control by the control unit 42. In this flowchart, various doors 6, 10, 14a, 14 of the air conditioner are shown.
Controls not directly related to the present invention, such as b, 14c and the blower 7, are omitted, and the control shown here is executed as part of a control routine that is repeatedly performed after the air conditioner is switched to the heating control mode. You.

First, in step 50, signals from the duct temperature sensor 40, the room temperature sensor 41 and the like are input, and in the next step 52, the duct temperature sensor 4
It is determined whether the inlet air temperature (evaporator inlet air temperature) of the evaporator detected by 0 is lower than a predetermined temperature (for example, a low temperature such as 0 ° C.).

If it is determined in step 52 that the air inlet air temperature is lower than the predetermined temperature, the process proceeds to step 54, where the hot water heater 27 is operated, the compressor 17 is stopped, and the hot water heater 25 is turned off.
Heat only by heating. As a result, the air introduced into the air conditioning duct is not heated and exchanged by the evaporator 8 and the sub-condenser 9, but is directly heated by the hot water heater 25 to be warmed and supplied to the passenger compartment.

Here, the presence or absence of the operation of the compressor 17
That is, the reason that the presence or absence of the operation of the refrigerant circulation cycle is based on the predetermined temperature having a low temperature is that the above-described heat pump configuration cannot obtain sufficient heating capacity when the intake air is below freezing. If the intake air temperature is lower than the predetermined temperature, there is no practical benefit in operating the refrigerant circulation cycle, so that the operation is stopped to save power. Therefore, this reference value can be set to a value lower than 0 ° C. as long as the heating capacity by the refrigerant circulation cycle can be sufficiently obtained even below the freezing point.

If it is determined in step 52 that the air inlet air temperature is equal to or higher than the predetermined temperature, it is determined in step 56 whether the vehicle interior temperature is lower than a target temperature (for example, 25 ° C.) If it is determined that the vehicle interior temperature is lower than the target temperature, the process proceeds to step 58, where both the compressor 17 and the hot water heating device 27 are operated.
Thereby, the air introduced into the air conditioning duct 2 is cooled and dehumidified by the evaporator 8, heated by the sub-condenser 9, further heated by the hot water heater 25, and supplied to the passenger compartment.

If it is determined in step 56 that the room temperature is equal to or higher than the target temperature, the process proceeds to step 60,
The compressor 17 is operated, and the hot water heating device 27 is stopped. At this time, since the room temperature exceeding the target temperature needs to be asymptotically approached to the target temperature, the opening of the air mix door 10 is adjusted in order to form a blowing temperature corresponding to the room temperature. As a result, the air introduced into the air conditioning duct 2 is cooled and dehumidified by the evaporator 8, and the air passing through the sub-condenser 9 is heated here, and then passes through the hot water heater 25. Is suppressed, and is mixed with air bypassing the sub-condenser 9 on the downstream side of the hot water heater 25 and supplied to the vehicle interior.

From the above, assuming a case where a vehicle that has been left in a place where the outside air is below freezing for a long time and the air conditioner is activated to heat the inside of the vehicle in the inside air circulation mode is as follows.
The air temperature at the inlet of the Eva roughly matches the cabin temperature,
While the room temperature is below the freezing point, only the auxiliary heater 25 operates to start heating.

In this state, as shown in FIG. 5, although there is some problem in the point of immediate heating, a larger heating capacity cannot be obtained by operating the heat pump.
The vehicle interior is heated solely by relying on the heating capacity of the auxiliary heater. Thereafter, when the vehicle compartment is warmed to 0 ° C. or higher, the compressor 17 is driven to start heating by the heat pump, and the air is warmed by both the sub-condenser 9 and the hot water heater 25. As a result, the vehicle interior is rapidly warmed toward the target temperature.

When the vehicle interior temperature exceeds the target temperature after a while, there is no longer a need for immediate heating, and at this point, only heating control by a heat pump is sufficient. Therefore, heating by the auxiliary heater 25 is stopped and only the heat pump is used. Keep the cabin temperature at the target value.

Accordingly, the auxiliary heater is activated when the outside air cannot be handled by the heat pump or when immediate heat is required while using the heat pump, and in other cases, the auxiliary heater is turned off to save power. Answer the request. Further, since the sub-condenser and the hot water heater are integrally formed, space can be saved, and at the same time, the supply of the refrigerant to the sub-condenser 9 and the hot water heater 25
Even when the supply of hot water to is stopped, the heat of one heat exchanger is transmitted to the components of the other heat exchanger,
Substantially, the heat radiation area is enlarged, and the heating capacity is enhanced.

[0042]

As described above, according to the present invention,
Since the third heat exchanger using the fluid heated by the fluid heating device arranged outside the vehicle as a heat source is arranged downstream of the first and second heat exchangers constituting the refrigerant circulation cycle, Even if foreign matter enters the air conditioning passage, there is no inconvenience such as short-circuiting of the electric system, and there is no danger that the occupant will get an electric shock due to the leakage of electricity. In addition, since there is no problem even if the third heat exchanger is disposed on the passenger compartment side, the air conditioning passage does not need to have a complicated shape that forms a branch passage, and the increase in passage resistance can be suppressed. it can.

In a low outside air condition where the heating capacity by the refrigerant circulation cycle is not sufficient, the air is heated only by the third heat exchanger, and the heating by the refrigerant circulation cycle can be performed effectively. When the temperature is low, the heating of the air by the refrigerant circulation cycle and the heating of the air by the third heat exchanger are used in combination to enhance the immediate warming property. Since the heating control is performed only by the cycle, it is possible to cope with an extremely low temperature region in which heating cannot be performed only by the refrigerant circulation cycle, and it is possible to save power while satisfying the demand for immediate warming.

Further, if the first heat exchanger and the third heat exchanger are integrally formed in order to save space, the operation of the compressor or the fluid heating device is stopped due to a demand for power saving. Even in this case, since the heat of one heat exchanger is transmitted to the other heat exchanger, the heat exchange area is substantially increased, and the heat exchange capacity can be increased.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an electric vehicle air conditioner according to the present invention.

FIG. 2 is a diagram showing a sub-condenser and a hot water heater used in the electric vehicle air conditioner;
(A) is a sectional view taken along the ventilation direction, FIG.
(B) shows a part of the front view.

FIG. 3 is another configuration example showing a sub-condenser and a hot water heater used in the air conditioner for an electric vehicle, and FIG. 3 (a) is a cross-sectional view cut along a ventilation direction;
FIG. 3B is a cross-sectional view of the tube used in FIG.

FIG. 4 is a flowchart illustrating an example of heating control by a control unit.

FIG. 5 is a characteristic diagram showing a change in room temperature during heating control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air-conditioning passage 2 Air-conditioning duct 8 Evaporator 9 Subcondenser 16 Expansion valve 17 Compressor 19 Main condenser 22 Bypass passage 25 Hot water heater 27 Hot water heating device

Claims (3)

[Claims] 1. A compressor, a first heat exchanger provided on a discharge side of the compressor, an expansion device for reducing the pressure of refrigerant passing through the first heat exchanger, and an outlet of the expansion device and A refrigerant circulation cycle including a second heat exchanger provided between the first heat exchanger and the second heat exchanger. The second heat exchanger and the first heat exchanger are provided in an air conditioning passage provided on the indoor side. An electric vehicle air conditioner arranged in this order from the upstream side, comprising: a fluid heating device arranged outside the cabin to heat the fluid; and a downstream side of the air conditioning passage downstream of the first heat exchanger. A third heat exchanger for circulating a fluid heated by the fluid heating device, wherein the compressor is stopped when an inlet air temperature of the second heat exchanger is lower than a first temperature. To make the fluid heating device When the inlet air temperature of the second heat exchanger is equal to or higher than the first temperature and the vehicle interior temperature is lower than the second temperature, the compressor and the fluid heating device are operated. An air conditioner for an electric vehicle, wherein the compressor is operated to stop the fluid heating device when the vehicle interior temperature is equal to or higher than the second temperature. 2. The refrigerant circulation cycle includes a path between the compressor and the first heat exchanger that passes through an external heat exchanger and a path that bypasses the external heat exchanger. The air conditioner for an electric vehicle according to claim 1, wherein the refrigerant is circulated only through a path that bypasses the exterior heat exchanger. 3. The air conditioner for an electric vehicle according to claim 1, wherein the third heat exchanger is formed integrally with the first heat exchanger.