JP2006232145A - Air-conditioner for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air-conditioner for a vehicle capable of performing a stable heating operation by enhancing the heating efficiency. <P>SOLUTION: The air-conditioner 1 for the vehicle is equipped with a compressor 7 to compress refrigerant to become super-critical on the discharge side, a refrigerant circuit 3 connected with the discharge side of the compressor 7, connected with an outdoor heat-exchanger 9 to condense the refrigerant and with the suction side of the compressor 9 and having an indoor heat-exchanger 11 to evaporate the condensed refrigerant, and a heating medium circuit 5 having a cooling water circuit 19 to circulate the engine cooling water and a heater core 21 arranged in the cooling water circuit 19, wherein the refrigerant circuit 3 is furnished upstream of the outdoor heat-exchanger 9 with a coolant heat-exchanger 23 to make heat exchange with the heating medium circuit 5 and with a bypass circuit 25 to suck the discharged refrigerant having passed the coolant heat-exchanger 23 to the suction side of the compressor 7 upon decompressing by a throttle 29. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle air conditioner.

Vehicle air conditioners that use hot gas from the compressor as an auxiliary heating source when the heating capacity of engine drive water, for example when the engine is started or when the outside air temperature is extremely low, is insufficient. As an apparatus, there exists a thing shown by patent document 1, for example.
This is because, during the refrigeration cycle, a heat exchanger that heats the engine coolant circulated to the heater core with a compressor discharge gas refrigerant is installed, and a condenser and a receiver are connected downstream of the heat exchanger. A bypass circuit for directly bypassing the gas refrigerant separated by the liquid receiver to the compressor suction side is provided, and the bypass circuit is provided with an electromagnetic valve.
During heating, if the temperature of the hot water is lower than the set temperature, the compressor is turned on, the condenser fan is stopped, the solenoid valve is opened, the bypass circuit is opened, and the engine coolant is compressed by the heat exchanger. Heating with hot gas from the machine increases the temperature of the engine cooling water to improve the heating capacity of the heater core.

Japanese Patent Laid-Open No. 10-297270 (paragraphs [0014] to [0021] and FIG. 1)

  However, since the compressor discharge gas refrigerant which heated engine cooling water passes through a condenser, what is shown by patent documents 1 will be further cooled with the condenser cooled to substantially outside temperature. For this reason, the temperature of the gas refrigerant sucked into the suction side of the compressor through the bypass circuit gradually decreases, so that the temperature of the discharged gas refrigerant does not rise sufficiently even when pressurized by the compressor. It becomes. Therefore, heating of the engine cooling water by the discharged gas refrigerant becomes insufficient and gradually decreases, so that there is a problem that heating efficiency is lowered and stable heating operation cannot be performed.

  An object of this invention is to provide the vehicle air conditioner which can improve heating efficiency and can perform the stable heating operation in view of the said problem.

In order to solve the above problems, the present invention employs the following means.
That is, a vehicle air conditioner according to the present invention includes a compressor that compresses a refrigerant that becomes supercritical on the discharge side, an outdoor heat exchanger that is connected to the discharge side of the compressor and cools the discharged refrigerant, and the compressor. A refrigerant circuit having a first indoor heat exchanger disposed between the suction side and the outdoor heat exchanger and evaporating the cooling refrigerant, a circulation path for circulating the heat medium, and a second circuit disposed in the circulation path A vehicle with a heat medium circuit having an indoor heat exchanger, wherein the first indoor heat exchanger and the second indoor heat exchanger are installed in a ventilation portion to a vehicle interior. Includes a heat exchanger for exchanging heat with the heat medium circuit on the upstream side of the outdoor heat exchanger, and the compressor is configured to depressurize the discharged refrigerant that has passed through the heat exchanger by a throttle means. There is a bypass circuit for suction on the suction side of And wherein the Rukoto.

According to the present invention, when heating operation is performed, the refrigerant discharged from the compressor passes through the bypass circuit, and the heat medium in the heat medium circuit is circulated. In the heat exchanger, the heat medium circulating in the heat medium circuit is heated by the high-temperature, high-pressure supercritical discharge refrigerant discharged from the compressor and supplied to the second indoor heat exchanger. The ventilation that passes around the second indoor heat exchanger is warmed and sent to the vehicle interior, so that the vehicle interior is heated.
Thus, since the heat medium circulating through the heat medium circuit is heated by the refrigerant discharged from the compressor in the supercritical state, a large amount of heat can be obtained. For this reason, efficient heating can be performed.

The discharged refrigerant that has been heat-exchanged by the heat exchanger and has reached a low temperature passes through the bypass circuit and is decompressed by the throttle means. The gas refrigerant that has been decompressed to low temperature and pressure is sucked into the suction side of the compressor. That is, the refrigerant is compressed by the compressor to become a supercritical high temperature and high pressure, releases heat by the heat exchanger to become low temperature, and repeats the heating cycle in which the refrigerant is decompressed and becomes a low pressure gas refrigerant.
Further, by providing an accumulator on the suction side of the compressor, the refrigerant in the heating cycle can be positioned on the saturated vapor line on the low pressure side sucked into the compressor, so that it is a refrigerant discharged in a supercritical state. However, the gas refrigerant can be reliably sucked into the compressor. For this reason, since the liquid refrigerant is not sucked into the compressor, it is possible to prevent the reliability of the compressor from being lowered.

Further, since the discharged refrigerant that has passed through the heat exchanger located on the upstream side of the outdoor heat exchanger flows in the bypass circuit, the refrigerant does not pass through the outdoor heat exchanger during heating. For this reason, even when the outdoor air temperature is low, the refrigerant is not cooled by the outdoor heat exchanger. Therefore, the temperature and pressure of the refrigerant sucked into the compressor are reduced, and the temperature and pressure of the refrigerant discharged from the compressor are reduced. There is no fear of decline.
Therefore, the amount of heat supplied to the heat medium by the heat exchanger can be maintained, so that stable heating operation can be performed. Moreover, since there is no possibility that the pressure of the refrigerant sucked into the compressor will be lowered, it is possible to prevent the reliability of the compressor from being lowered.
Even when the refrigerant circuit is in cooling operation, the discharged refrigerant can transfer the amount of heat to the heat medium of the heat medium circuit, so the heat exchanger and the outdoor heat exchanger can be used in series as a radiator, Cooling efficiency can be improved.

  Moreover, in the said invention, it is preferable that the said refrigerant circuit is provided with the switching means which can selectively change the flow direction of the said discharge refrigerant | coolant in the branch position where the said bypass circuit branches.

  An air conditioner for a vehicle according to the present invention includes a compressor that compresses a refrigerant that is supercritical on the discharge side, an outdoor heat exchanger that is connected to the discharge side of the compressor and cools the discharged refrigerant, and the compressor. A refrigerant circuit that is disposed between the suction side and the outdoor heat exchanger and has a first indoor heat exchanger that evaporates the cooling refrigerant, a circulation path that circulates the heat medium, and a second circuit that is disposed in the circulation path. A vehicle air conditioner, wherein the first indoor heat exchanger and the second indoor heat exchanger are installed in a ventilation portion into a vehicle compartment, and a heat medium circuit having two indoor heat exchangers, The refrigerant circuit is installed between the compressor and the outdoor heat exchanger, and exchanges heat with the heat medium circuit, and between the heat exchanger and the outdoor heat exchanger. A bypass circuit connecting the branch position of the compressor and the suction side of the compressor, and the branch position And selectively changeable switching means in the direction of refrigerant flow definitive, a throttle means provided in the bypass circuit, characterized in that is provided.

According to the present invention, when performing the heating operation, the switching means allows the refrigerant from the compressor to pass through the bypass circuit and circulates the heat medium in the heat medium circuit. In the heat exchanger, the heat medium circulating in the heat medium circuit is heated by the high-temperature, high-pressure supercritical discharge refrigerant discharged from the compressor and supplied to the second indoor heat exchanger. Ventilation passing around the second indoor heat exchanger is warmed and sent to the passenger compartment.
Thus, since the heat medium circulating through the heat medium circuit is heated by the refrigerant discharged from the compressor in the supercritical state, a large amount of heat can be obtained. For this reason, efficient heating can be performed.

The discharged refrigerant that has been heat-exchanged by the heat exchanger and has reached a low temperature passes through the bypass circuit and is decompressed by the throttle means. The gas refrigerant that has been decompressed to low temperature and pressure is sucked into the suction side of the compressor. That is, the refrigerant is compressed by the compressor to become a supercritical high temperature and high pressure, releases heat by the heat exchanger to become low temperature, and repeats the heating cycle in which the refrigerant is decompressed and becomes a low pressure gas refrigerant.
Further, by providing an accumulator on the suction side of the compressor, the refrigerant in the heating cycle can be positioned on the saturated vapor line on the low pressure side sucked into the compressor, so that it is a refrigerant discharged in a supercritical state. However, the gas refrigerant can be reliably sucked into the compressor. For this reason, since the liquid refrigerant is not sucked into the compressor, it is possible to prevent the reliability of the compressor from being lowered.
This can be done more reliably and easily if an accumulator is provided on the suction side of the compressor.

Moreover, since the branch position of the bypass circuit is on the upstream side of the outdoor heat exchanger, the refrigerant does not pass through the outdoor heat exchanger during heating. For this reason, even when the outdoor air temperature is low, the refrigerant is not cooled by the outdoor heat exchanger. Therefore, the temperature and pressure of the refrigerant sucked into the compressor are reduced, and the temperature and pressure of the refrigerant discharged from the compressor are reduced. There is no fear of decline.
Therefore, the amount of heat supplied to the heat medium by the heat exchanger can be maintained, so that stable heating operation can be performed. Moreover, since there is no possibility that the pressure of the refrigerant sucked into the compressor will be lowered, it is possible to prevent the reliability of the compressor from being lowered.
Even when the refrigerant circuit is in cooling operation, the discharged refrigerant can transfer the amount of heat to the heat medium of the heat medium circuit, so the heat exchanger and the outdoor heat exchanger can be used in series as a radiator, Cooling efficiency can be improved.

  The vehicle air conditioner according to the present invention is characterized in that an oil separator is disposed between the heat exchanger and the branch position.

As described above, since the oil separator is disposed between the heat exchanger and the branch position, the heat amount of the lubricating oil contained in the discharged refrigerant can be effectively utilized in the heat exchanger.
Further, since the lubricating oil contained in the discharged refrigerant can be recovered by the oil separator, the amount of lubricating oil circulated to the outdoor heat exchanger or the like during the cooling operation can be reduced. For this reason, the amount of lubricating oil that accumulates in the outdoor heat exchanger or the like that occurs when switching to heating operation can be suppressed to a small amount, so that there is insufficient lubricating oil during heating operation, which hinders compressor operation. Can be prevented.

  In the vehicle air conditioner according to the present invention, an oil separator is disposed at the branch position, an electromagnetic valve is used as the throttle means, and the refrigerant is supplied from the oil separator to an outdoor heat exchanger as the switching means during heating operation. It is characterized by using a regulating valve for regulating the flow.

According to the present invention, during cooling operation, the regulating valve is opened so that the refrigerant flows to the outdoor heat exchanger, while the electromagnetic valve is opened small and the lubricating oil separated by the oil separator is compressed through the bypass circuit. Flow on the suction side of the machine.
Then, during the heating operation, the regulating valve is closed, and the electromagnetic valve is opened to make a gentle throttle act. By doing so, the refrigerant flows through the bypass circuit together with the lubricating oil, and is throttled to a low pressure by the electromagnetic valve.
Thus, since the bypass circuit can be utilized for collecting the lubricating oil collected by the oil separator, the circuit configuration is simplified and the apparatus can be made inexpensive.

  In the vehicle air conditioner according to the present invention, the heat medium is cooling water for a vehicle drive device.

When the vehicle drive device is an engine, the engine cooling water becomes sufficiently high when the engine is sufficiently warmed. Therefore, when the temperature of the engine cooling water exceeds a predetermined temperature, the operation of the compressor can be stopped. .
In this way, when the engine is started up or when the outside air temperature is extremely low, the heating operation in the refrigerant circuit is used when heating using only engine cooling water is insufficient. Heating capacity can be maintained without increasing the power drop.

  According to the present invention, during the heating operation, the heat medium of the heat medium circuit is heated by the discharged refrigerant in the supercritical state, and the heated refrigerant returns to the suction side of the compressor without passing through the outdoor heat exchanger. As a result, heating efficiency is improved and stable heating operation can be performed.

Embodiments according to the present invention will be described below with reference to the drawings.
[First embodiment]
FIG. 1 shows an outline of a vehicle air conditioner 1 according to the present embodiment.
The vehicle air conditioner 1 includes a refrigerant circuit 3 that performs a cooling operation and a heat medium circuit 5 that performs a heating operation.
The refrigerant circuit 3 mainly includes a compressor 7 that compresses the refrigerant, an outdoor heat exchanger 9, an expansion valve 11, an indoor heat exchanger (first indoor heat exchanger) 13, and an accumulator 15. Yes.

The compressor 3 is driven by the engine 17 via a clutch (not shown), compresses carbon dioxide as a refrigerant, and for example, a scroll compressor is used.
The outdoor heat exchanger 9 is connected to the discharge side of the compressor 7, exchanges heat with the outside air, and operates as a radiator during cooling operation.
The expansion valve 11 depressurizes the high-pressure refrigerant into a low-temperature and low-pressure refrigerant. The expansion valve 11 is, for example, electronically operated, and the refrigerant flow rate is adjusted so that the high-pressure side refrigerant pressure is maintained at a predetermined value.
The indoor heat exchanger 13 exchanges heat between the gaseous refrigerant and the air blown into the vehicle interior, and supplies cold air to the vehicle interior.
The accumulator 15 collects moisture from the refrigerant and supplies the gaseous refrigerant to the suction side of the compressor 7.

The heat medium circuit 5 includes a cooling water circuit (circulation path) 19 that circulates engine cooling water of the engine 17, and a heater core (second indoor heat exchanger) 21 that exchanges heat between the engine cooling water and the air in the passenger compartment. Is provided.
The coolant circuit 19 circulates engine coolant heated by the heat generated by the engine 17 by a pump (not shown), and the circulation amount is adjusted by a flow rate control valve (not shown).
The heater core 21 exchanges heat between the engine cooling water and the air blown into the vehicle interior, and supplies warm air to the vehicle interior.

The refrigerant circuit 3 is provided with a coolant heat exchanger (heat exchanger) 23 on the discharge side of the compressor 7. The coolant heat exchanger 23 exchanges heat between the engine coolant of the engine 17 and the compressed refrigerant.
In the heat medium circuit 5, the coolant heat exchanger 23 is arranged on the side where the engine coolant in the coolant circuit 19 flows into the heater core 21.
The refrigerant circuit 3 includes a position A located downstream of the coolant heat exchanger 23 and upstream of the outdoor heat exchanger 9, and a position B located between the indoor heat exchanger 13 and the accumulator 15. A connecting bypass circuit 25 is provided. The position A is provided with a three-way valve (switching means) 27 for switching whether the refrigerant from the compressor 9 is sent to the outdoor heat exchanger 9 side of the refrigerant circuit 3 or to the bypass circuit 25.
The bypass circuit 27 is provided with a diaphragm (a diaphragm means) 29. The throttle 29 depressurizes the refrigerant from the compressor 7 and becomes a liquid / gas mixed refrigerant depending on the situation.

The indoor heat exchanger 13 and the heater core 21 are composed of an HVAC unit (Heating,
Ventilating and Air-Conditioning) 31. The HVAC unit 31 adjusts the temperature of air (outside air or vehicle interior air) supplied to the vehicle interior, and the blower 33, the indoor heat exchanger 13 and the heater core 21 are sequentially arranged from the upstream side (downward in the figure). That is, they are provided in series. An air mix damper 35 is provided on the upstream side of the heater core 21. By adjusting the opening degree of the air mix damper 35, the flow rate of the cold air that has passed through the indoor heat exchanger 13 flows through the heater core 21.

The vehicle air conditioner 1 configured as described above operates as follows.
During cooling (see the dotted line in FIG. 1), the refrigerant compressed by the compressor 3 is cooled by the coolant heat exchanger 23, and then flows through the three-way valve 27 to the outdoor heat exchanger 9. The compressed refrigerant is in a supercritical state because carbon dioxide is used as the refrigerant.
In the outdoor heat exchanger 9, heat is exchanged with the outside air, and the high-pressure refrigerant is cooled.
The high-pressure refrigerant radiated by the outdoor heat exchanger 9 is throttled by the expansion valve 11 and depressurized. The refrigerant decompressed by the expansion valve 11 becomes a low-pressure refrigerant and is led to the indoor heat exchanger 13.

In the indoor heat exchanger 13, heat exchange is performed between the air (outside air or vehicle interior air) guided from the blower 33 and the low-pressure refrigerant, and the low-pressure refrigerant evaporates. The amount of heat is deprived by the latent heat of vaporization of the low-pressure refrigerant, and the air is cooled and guided to the downstream heater core 21.
The refrigerant evaporated in the indoor heat exchanger 13 becomes a low-pressure gas refrigerant and is led to the accumulator 15. The low-pressure gas refrigerant is guided to the suction side of the compressor 3 after moisture is removed by the accumulator 15.

  In the HVAC unit 31, air (outside air or vehicle interior air) introduced from the blower 33 is cooled by the indoor heat exchanger 13, and then warmed by the heater core 21 into which engine cooling water is introduced, and guided to the vehicle interior. . Cooling water that has cooled the discharge gas from the compressor 3 is guided to the heater core 21, and the amount of heat taken from the discharge gas can be effectively recovered by the heater core 16. The amount of heating given to the air by the heater core 21 is adjusted by the air mix damper 35.

  During heating (see the solid line and broken line in FIG. 1), a flow rate control valve (not shown) is opened to allow the engine coolant to flow down the coolant circuit 19. Then, a pump (not shown) is driven to circulate the engine coolant warmed by the heat generated by the engine to the coolant circuit 19. The circulated warm engine cooling water comes into contact with the air passing through the HVAC unit 31 by passing through the heater core 21, and the air is radiated from the engine cooling water to become warm air and sent to the vehicle interior.

For example, when the engine 17 is started or when the outside air temperature is very low, the heating from the heater core 21 using only engine cooling water is insufficient in the heating capacity, and the refrigerant from the compressor 9 is used as an auxiliary heating source. Utilize as.
That is, a clutch (not shown) is connected, and the compressor 7 is driven by the engine 17 so that the three-way valve communicates with the switching bypass circuit 25. Thereby, a heating cycle is formed by the compressor 7, the coolant heat exchanger 23, the throttle 29 and the accumulator 15. The behavior of the heating cycle will be described with reference to the Mollier chart shown in FIG.
Since the refrigerant separated into gas and liquid by the accumulator 15 and sucked into the compressor 7 is in the state of saturated steam, it is located at the point X on the saturated steam line.
This refrigerant is compressed by the compressor 7 to be a supercritical high-temperature and high-pressure refrigerant (point Y) and discharged.

The refrigerant discharged from the compressor 7 is cooled by giving heat to the engine coolant flowing through the coolant circuit 19 in the coolant heat exchanger 23 (point Z). As a result, the engine coolant flowing through the coolant circuit 19 is supplied with heat by the refrigerant from the compressor 7 in the coolant heat exchanger 23, and the coolant temperature is raised. Since the cooling water whose temperature of the cooling water has been raised flows into the heater core 21, the amount of heat supply in the heater core 21 increases, and the heating capacity can be improved.
Then, the cooled and cooled refrigerant passes through the three-way valve 27 and is led to the bypass circuit 25. The refrigerant introduced into the bypass circuit 25 is throttled and depressurized by the throttle 29 (point A), and flows into the accumulator 15. The refrigerant whose moisture has been collected by the accumulator 15 is sucked into the suction side of the compressor 9.
For example, when the engine 17 is sufficiently warmed, the engine cooling water becomes sufficiently high. For example, the temperature of the engine cooling water is measured, and when the temperature exceeds a predetermined temperature, the compressor is cooled. The operation of 7 is stopped.

According to this embodiment, there exist the following effects.
When the engine 17 is started or when the outside air temperature is extremely low and the heating capacity is insufficient with only the engine cooling water, the refrigerant from the compressor 7 is caused to pass through the bypass circuit 25 by the three-way valve 27, and the heat medium The engine coolant is circulated through the circuit 5. In the coolant heat exchanger 23, the engine coolant circulating through the heat medium circuit 5 is heated by the high-temperature and high-pressure supercritical refrigerant discharged from the compressor 7 and supplied to the heater core 21. The air passing around the heater core is warmed by the blower 33 and sent to the passenger compartment.
Thus, the engine coolant circulating in the heat medium circuit 5 is heated by the refrigerant from the compressor 7 in the supercritical state, so that a large amount of heat can be obtained. For this reason, even when the engine 17 is started or when the outside air temperature is very low or the like, even when heating by the heater core 21 using only engine cooling water is insufficient in heating capacity, the amount of heat can be reinforced immediately. Therefore, sufficient heating can be performed efficiently.

The refrigerant cooled by applying heat to the cooling water in the coolant heat exchanger 23 passes through the bypass circuit 25 and is decompressed by the throttle 29. The decompressed refrigerant is sucked into the suction side of the compressor 7 after moisture is collected by the accumulator 15. That is, the refrigerant is compressed by the compressor 7 to become high temperature and pressure, releases heat by the coolant heat exchanger 23 to become low temperature, and repeats the heating cycle in which the pressure is reduced by the throttle 29 and becomes low pressure.
Therefore, the refrigerant in the heating cycle is gas-liquid separated by the accumulator 15 and is sucked into the compressor 7 as a gas refrigerant. Therefore, even if the refrigerant is discharged in a supercritical state, the refrigerant is reliably sucked into the compressor 7. Can be made. For this reason, since the liquid refrigerant is not sucked into the compressor 7, it is possible to prevent the reliability of the compressor 7 from being lowered.

Further, since the branch position A of the bypass circuit 25 is on the upstream side of the outdoor heat exchanger 9, the refrigerant does not pass through the outdoor heat exchanger 9 during heating. For this reason, even when the outdoor air temperature is low, the refrigerant is not cooled by the outdoor heat exchanger 9, so the temperature of the refrigerant sucked into the compressor 7 decreases and the temperature of the refrigerant discharged from the compressor 7 decreases. There is no fear of doing.
Therefore, the amount of heat supplied to the heat medium by the coolant heat exchanger 23 can be maintained, so that stable heating operation can be performed.
Moreover, since there is no possibility that the pressure of the refrigerant sucked into the compressor 7 is also reduced, it is possible to prevent the reliability of the compressor 7 from being lowered.
Even when the refrigerant circuit 3 is in the cooling operation, the discharged refrigerant can transfer the amount of heat to the heat medium of the heat medium circuit 5, so that the coolant heat exchanger 23 and the outdoor heat exchanger 9 are used in series as a radiator. It is possible to improve the cooling efficiency.

In the present embodiment, carbon dioxide is used as the refrigerant. However, the refrigerant used in the present invention is not limited to this, and may be another refrigerant (for example, ethane) that can be in a supercritical state after compression.
In the present embodiment, the vehicle drive device is an engine, but the vehicle drive device used in the present invention is not limited to this, and may be a fuel cell or a motor.
In the present embodiment, the compressor is driven by an engine, but the compressor used in the present invention is not limited to this and may be electrically driven.

In addition, as shown in FIG. 3, an internal heat exchanger 37 may be provided between the downstream side of the outdoor heat exchanger 9 and the suction side of the compressor 7.
In this way, the internal heat exchanger 20 exchanges heat between the high-pressure side refrigerant and the low-pressure refrigerant on the suction side of the compressor 7, and the high-pressure refrigerant that has passed through the outdoor heat exchanger 9 during cooling provides supercooling. As a result, the dryness of the refrigerant at the inlet of the indoor heat exchanger 13 can be lowered. On the other hand, since the temperature of the refrigerant sucked into the compressor 7 is raised, the efficiency of the refrigeration cycle can be improved.

Furthermore, as shown in FIG. 4, an oil separator 39 may be provided between the coolant heat exchanger 23 and the three-way valve 27 in the refrigerant circuit 3.
In this way, the refrigerant containing the lubricating oil from the compressor 7 is cooled by the coolant heat exchanger 23 and introduced into the oil separator 39. In the oil separator 39, the lubricating oil contained in the refrigerant is separated and returned to the compressor 7.
Thus, since the oil separator 39 is arranged between the coolant heat exchanger 23 and the three-way valve 27 (branch position A), the amount of heat of the lubricating oil contained in the refrigerant is also effectively increased by the coolant heat exchanger 23. Can be used.
Further, since the lubricating oil contained in the refrigerant can be recovered by the oil separator 39, the amount of lubricating oil circulated to the outdoor heat exchanger 9 and the like during the cooling operation can be reduced. For this reason, the amount of lubricating oil accumulated in the outdoor heat exchanger 9 or the like that occurs when switching to the heating operation can be suppressed to a small amount, so that the lubricating oil is insufficient during the heating operation, which hinders the operation of the compressor 7. Can be prevented.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
In this embodiment, the structure of the part relevant to the heating operation in the refrigerant circuit 3 is different from that of the first embodiment described above. Since other components are the same as those of the first embodiment described above, description of these components is omitted here.
In addition, the same code | symbol is attached | subjected to the member same as 1st embodiment mentioned above.

That is, in this embodiment, the oil separator 41 is installed at the branch position A.
An electromagnetic valve (a regulating valve as a switching means) 43 is provided on the downstream side of the oil separator 41 of the refrigerant circuit 3. The solenoid valve 43 is configured to be closed when the refrigerant circuit 3 performs a heating operation, and to block the flow of the refrigerant to the outdoor heat exchanger 9, and to be opened when the cooling operation is performed.
A solenoid valve (throttle means) 45 with a bypass port is provided on the oil separator 41 side of the bypass circuit 25.

The vehicle air conditioner 1 according to the present embodiment configured as described above operates as follows.
During the cooling operation, the electromagnetic valve 45 is placed with a small opening (tight throttle). By doing so, only the lubricating oil separated by the oil separator 41 passes through the bypass circuit 25 and is returned to the suction side of the compressor 7.
Since other operations are the same as those in the first embodiment, a duplicate description is omitted here.

When the coolant heat exchanger 23 of the refrigerant circuit 3 is used as an auxiliary heating source during heating, the electromagnetic valve 43 is closed so that the refrigerant from the compressor 7 is not introduced into the outdoor heat exchanger 9. Further, the opening degree of the electromagnetic valve 45 is increased (a loose throttle) so that the refrigerant can pass through the bypass circuit 25 together with the lubricating oil separated by the oil separator 41.
In this state, a clutch (not shown) is connected, and the compressor 7 is driven by the engine 17. The refrigerant from the compressor 7 is introduced into the oil separator 41 via the coolant heat exchanger 23.
The engine coolant flowing through the coolant circuit 19 is supplied with heat by the refrigerant from the compressor 7 in the coolant heat exchanger 23, and the coolant temperature is raised. Since the cooling water whose temperature of the cooling water has been raised flows into the heater core 21, the amount of heat supply in the heater core 21 increases, and the heating capacity can be improved.

The refrigerant introduced from the oil separator 41 to the bypass circuit 25 is throttled and depressurized by the electromagnetic valve 45, flows into the accumulator 15, and moisture is collected by the accumulator 15 and then sucked into the suction side of the compressor 9. The
For example, when the engine 17 is sufficiently warmed up, the engine cooling water becomes sufficiently hot. For example, the temperature of the engine cooling water is measured, and when the temperature becomes a predetermined temperature abnormality, the compressor is cooled. The operation of 7 is stopped.

  Thus, since the solenoid valve 43 can be used for switching during cooling and heating operation, and the bypass circuit 25 can be used for recovery of lubricating oil during cooling operation, the circuit configuration is provided despite having various functions. Is simplified and can be manufactured at low cost.

Also in the present embodiment, as shown in FIG. 3, an internal heat exchanger 37 may be provided between the downstream side of the outdoor heat exchanger 9 and the suction side of the compressor 7.
In this way, the internal heat exchanger 20 exchanges heat between the high-pressure side refrigerant and the low-pressure refrigerant on the suction side of the compressor 7, and the high-pressure refrigerant that has passed through the outdoor heat exchanger 9 during cooling provides supercooling. As a result, the dryness of the refrigerant at the inlet of the indoor heat exchanger 13 can be lowered. On the other hand, the temperature of the refrigerant sucked into the compressor 7 is raised.

In the present embodiment, the refrigerant is carbon dioxide, but the refrigerant used in the present invention is not limited to this, and may be another refrigerant (for example, ethane) that can be in a supercritical state after compression.
In the present embodiment, the vehicle drive device is an engine, but the vehicle drive device used in the present invention is not limited to this, and may be a fuel cell or a motor.
In the present embodiment, the compressor is driven by an engine, but the compressor used in the present invention is not limited to this and may be electrically driven.

1 is a block diagram showing an overall schematic configuration of a vehicle air conditioner according to a first embodiment of the present invention. It is a Mollier diagram which shows the behavior of the heating cycle of 1st embodiment. It is a block diagram which shows another embodiment of 1st embodiment. It is a block diagram which shows another embodiment of 1st embodiment. It is a block diagram which shows the whole schematic structure of the vehicle air conditioner concerning 2nd embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle air conditioner 3 Refrigerant circuit 5 Heat medium circuit 7 Compressor 9 Outdoor heat exchanger 13 Indoor heat exchanger 19 Cooling water circuit 21 Heater core 23 Coolant heat exchanger 25 Bypass circuit 27 Three-way valve 29 Restriction 31 HVAC unit 43 Solenoid valve 45 Solenoid valve
A Branch position

Claims (6)

A compressor that compresses supercritical refrigerant on the discharge side, an outdoor heat exchanger that is connected to the discharge side of the compressor and cools the discharged refrigerant, and between the suction side of the compressor and the outdoor heat exchanger A refrigerant circuit having a first indoor heat exchanger disposed and evaporating the cooling refrigerant;
A heat medium circuit having a circulation path for circulating the heat medium and a second indoor heat exchanger disposed in the circulation path,
In the vehicle air conditioner in which the first indoor heat exchanger and the second indoor heat exchanger are installed in the ventilation portion to the vehicle interior,
In the refrigerant circuit,
A heat exchanger for exchanging heat with the heat medium circuit is provided on the upstream side of the outdoor heat exchanger,
A vehicle air conditioner comprising a bypass circuit for reducing the pressure of the discharged refrigerant that has passed through the heat exchanger by a throttle means and sucking the refrigerant to a suction side of the compressor.
2. The vehicle according to claim 1, wherein the refrigerant circuit is provided with switching means capable of selectively changing a flow direction of the discharged refrigerant at a branch position where the bypass circuit is branched. Air conditioner. A compressor that compresses supercritical refrigerant on the discharge side, an outdoor heat exchanger that is connected to the discharge side of the compressor and cools the discharged refrigerant, and between the suction side of the compressor and the outdoor heat exchanger A refrigerant circuit having a first indoor heat exchanger disposed and evaporating the cooling refrigerant;
A heat medium circuit having a circulation path for circulating the heat medium and a second indoor heat exchanger disposed in the circulation path,
In the vehicle air conditioner in which the first indoor heat exchanger and the second indoor heat exchanger are installed in the ventilation portion to the vehicle interior,
In the refrigerant circuit,
A heat exchanger installed between the compressor and the outdoor heat exchanger, for exchanging heat with the heat medium circuit;
A bypass circuit that connects a branch position between the heat exchanger and the outdoor heat exchanger and a suction side of the compressor;
Switching means capable of selectively changing the direction of refrigerant flow at the branch position;
And a throttle means provided in the bypass circuit. The vehicle air conditioner according to claim 2 or 3, wherein an oil separator is disposed between the heat exchanger and the branch position. An oil separator is disposed at the branch position,
Using a solenoid valve as the throttling means,
The vehicle air conditioner according to claim 2 or 3, wherein a restriction valve for restricting a flow of refrigerant from the oil separator to the outdoor heat exchanger during heating operation is used as the switching means. The vehicle air conditioner according to any one of claims 1 to 5, wherein the heat medium is cooling water of a vehicle drive device.

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