WO2023248706A1 - Vehicle air conditioning device - Google Patents

Abstract

[Problem] To prevent liquid condensation in a compressor while maintaining heating capacity even when the outside air temperature is particularly low. [Solution] Provided is a vehicle air conditioning device comprising a refrigerant circuit in which a compressor, a condenser, an expansion unit, an evaporator, and a gas-liquid separation unit are connected in this order by refrigerant piping and a refrigerant is made to circulate, wherein the refrigerant circuit comprises: a first bypass path that causes refrigerant discharged from the compressor to flow into the inlet side of the gas-liquid separation unit; and an internal heat exchanger that causes heat exchange between refrigerant flowing toward the compressor from the gas-liquid separation unit and refrigerant flowing out from the condenser.

Description

Vehicle air conditioner

The present invention relates to an air conditioner for a vehicle.

As a vehicle air conditioner, one using a heat pump type refrigerant circuit is known. Such a vehicle air conditioner is equipped with a refrigerant circuit that includes a compressor, a condenser for heat radiation, an expansion mechanism, and an evaporator for heat absorption. Temperature-controlled air is blown into the vehicle interior by indirectly exchanging heat via a heat medium.

In a heat pump type refrigerant circuit, when the outside air is at an extremely low temperature (for example, −10° C.), the density of the refrigerant sucked into the compressor becomes low, resulting in insufficient heating capacity. For this reason, for example, auxiliary heat sources such as electric heaters are used to supplement heating capacity.
On the other hand, in order to ensure heating capacity without installing an auxiliary heat source, the high-temperature, high-pressure gas refrigerant discharged from the compressor is returned to the suction side of the compressor without passing through a heat exchanger, making it dependent on the outside temperature. There are some methods that increase the suction density of refrigerant without increasing the refrigerant intake density (for example, Patent Document 1).

Japanese Patent Application Publication No. 5-223357

As in the prior art described above, when the high-temperature, high-pressure gas refrigerant discharged from the compressor is returned to the suction side of the compressor, it is difficult to adjust the suction dryness of the compressor. Therefore, protective measures are required to prevent the compressor from causing liquid compression.

The present invention aims to address such problems. That is, an object of the present invention is to prevent liquid compression in a compressor while ensuring heating capacity even when the outside air temperature is particularly low in a vehicle air conditioner equipped with a heat pump type refrigerant circuit.

In order to solve such problems, one embodiment of the present invention includes the following configuration.
That is, a vehicle air conditioner according to one aspect of the present invention includes a refrigerant circuit that sequentially connects a compressor, a condenser, an expansion section, an evaporator, and a gas-liquid separation section through refrigerant piping and circulates refrigerant. In the vehicle air conditioner, the refrigerant circuit includes a first bypass flow path through which refrigerant discharged from the compressor flows into an inlet side of the gas-liquid separation section, and a flow path from the gas-liquid separation section to the compressor. It includes an internal heat exchanger that exchanges heat between the refrigerant flowing toward the condenser and the refrigerant flowing out from the condenser.

According to the vehicle air conditioner of the present invention having such features, it is possible to prevent liquid compression in the compressor while ensuring heating capacity even when the outside air temperature is particularly low.

FIG. 1 is an explanatory diagram showing a schematic configuration of a refrigerant circuit applied to a vehicle air conditioner according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing the flow of refrigerant during heating operation in the refrigerant circuit applied to the vehicle air conditioner according to the embodiment of the present invention. FIG. 2 is an explanatory diagram showing the flow of refrigerant during heating operation when the outside air is at an extremely low temperature in a refrigerant circuit applied to a vehicle air conditioner according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing the flow of refrigerant during cooling operation in a refrigerant circuit applied to a vehicle air conditioner according to an embodiment of the present invention. 1 is an explanatory diagram showing a schematic configuration of a vehicle air conditioner according to Example 1 of the present invention. FIG. 2 is an explanatory diagram showing the flow of refrigerant during heating operation when the outside air is at an extremely low temperature in the vehicle air conditioner according to Example 1 of the present invention. FIG. 2 is an explanatory diagram showing a schematic configuration of a vehicle air conditioner according to a second embodiment of the present invention. FIG. 7 is an explanatory diagram showing the flow of refrigerant during heating operation when the outside air is at an extremely low temperature in the vehicle air conditioner according to Example 2 of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals in different figures indicate parts with the same function, and redundant explanation in each figure will be omitted as appropriate.

As shown in FIG. 1, the refrigerant circuit R applied to the vehicle air conditioner according to the embodiment of the present invention includes a compressor 11, a condenser 12, an expansion valve 13, an evaporator 14, an accumulator 15, and an internal heat exchanger. The refrigerant pipes 16 are connected by refrigerant pipes 120A to 120H to circulate the refrigerant.

The refrigerant outlet of the compressor 11 and the refrigerant inlet of the condenser 12 are connected by a refrigerant pipe 120A, and the refrigerant outlet of the condenser 12 and the refrigerant inlet of the high pressure side flow path 16A of the internal heat exchanger 16 are connected by a refrigerant pipe 120B. It is connected. The refrigerant outlet of the high pressure side flow path 16A of the internal heat exchanger 16 and the refrigerant inlet of the evaporator 14 are connected by a refrigerant pipe 120C. The expansion valve 13 is provided in the refrigerant pipe 120C. The refrigerant outlet of the evaporator 14 and the refrigerant inlet of the accumulator 15 are connected by a refrigerant pipe 120D, and the accumulator 15 and the refrigerant inlet of the low pressure side flow path 16B of the internal heat exchanger 16 are connected by a refrigerant pipe 120E. The refrigerant outlet of the low pressure side flow path 16B of the internal heat exchanger 16 and the refrigerant inlet of the compressor 11 are connected by a refrigerant pipe 120F.

The refrigerant pipe 120A connecting the compressor 11 and the condenser 12 branches at a branch part 121 provided at the refrigerant outlet of the compressor 11, and one end of the refrigerant pipe 120G is connected to the branch part 121. There is. The other end of the refrigerant pipe 120G is connected to a confluence section 122 provided on the upstream side of the accumulator 15 of the refrigerant pipe 120D. The refrigerant pipe 120G is provided with an electronic expansion valve 18, and by opening the electronic expansion valve 18, a first bypass flow path is configured to guide the refrigerant discharged from the compressor 11 to the inlet side of the accumulator 15. Can be done.

The refrigerant pipe 120B that connects the condenser 12 and the high-pressure side flow path 16A of the internal heat exchanger 16 branches at a branch part 123, and one end of the refrigerant pipe 120H is connected to the branch part 123. The other end of the refrigerant pipe 120H is connected to a confluence section 124 provided on the upstream side of the expansion valve 13 of the refrigerant pipe 120C. The refrigerant pipe 120H is provided with a flow rate adjustment section 19, and by opening the flow rate adjustment section 19, the refrigerant flowing out from the condenser 12 is expanded by bypassing the high pressure side flow path 16A of the internal heat exchanger 16. A second bypass flow path leading to the valve 13 can be configured.

In the refrigerant circuit R configured as described above, the opening of the expansion valve 13, the electronic expansion valve 18, and the flow rate adjustment unit 19 is controlled by a control unit (not shown) according to the purpose of air conditioning in the vehicle air conditioner to which the refrigerant circuit R is applied. At the same time, the rotation speed of the compressor 11 is controlled to circulate the refrigerant.

In particular, with respect to the flow rate adjustment unit 19, the control unit controls the state of the refrigerant discharged from the compressor 11 (pressure, temperature, degree of dryness and degree of superheating) or the state of the refrigerant at the outlet of the accumulator 15 (pressure, temperature, degree of dryness). The opening degree is appropriately adjusted between fully closed and fully open based on the temperature and degree of superheating.

For example, the control unit estimates the degree of superheat from the state (pressure, temperature, etc.) of the refrigerant at the outlet of the compressor 11, that is, the state of the refrigerant discharged from the compressor 11, and adjusts the flow rate based on the estimated degree of superheat. By adjusting and controlling the opening degree of the portion 19, the flow rate of the refrigerant passing through the second bypass flow path is adjusted.

If the degree of superheat is greater than a predetermined threshold value, liquid compression is unlikely to occur, but if it is less than the threshold value, it is estimated that there is a high possibility that liquid compression will occur. Therefore, by adjusting the flow rate of the refrigerant passing through the second bypass flow path by the flow rate adjustment unit 19 so that the degree of superheat becomes larger than the threshold value, the refrigerant passes through the high pressure side flow path 16A of the internal heat exchanger 16. Adjust the refrigerant flow rate. Thereby, the amount of heat exchanged in the internal heat exchanger 16 can be controlled.

Also, from the state of the refrigerant on the discharge side of the compressor 11 and the state (pressure, temperature, etc.) of the refrigerant on the suction side of the compressor 11, that is, the outlet of the accumulator 15, the suction dryness of the compressor 11 under normal conditions can be determined. Since the adiabatic compression efficiency of the compressor 11 is determined as (for example, 0.95), the discharge temperature of the compressor 11 during normal operation can be determined. This makes it possible to determine whether the compressor 11 is operating normally, that is, whether liquid compression is occurring.

Therefore, the control unit estimates the suction dryness of the compressor 11 from the state of the refrigerant discharged from the compressor 11 and the state of the refrigerant at the outlet of the accumulator 15, and based on the estimated suction dryness, the second bypass flow By adjusting the flow rate of the refrigerant passing through the channel, the flow rate of the refrigerant passing through the high pressure side flow channel 16A of the internal heat exchanger 16 is adjusted. Thereby, the amount of heat exchanged in the internal heat exchanger 16 can be controlled.

In addition, in FIGS. 2 to 4, refrigerant piping through which high-pressure refrigerant passes is shown by a solid line, refrigerant piping through which low-pressure refrigerant passes by a dashed line, and refrigerant piping through which refrigerant does not pass is shown by a broken line.

(Flow of refrigerant during heating operation)
For example, when heating operation is performed immediately after starting the vehicle air conditioner, the refrigerant is circulated in the refrigerant circuit R as follows.
As shown in FIG. 2, in the refrigerant circuit R, the first bypass flow path (refrigerant pipe 120G) is not used, that is, the electronic expansion valve 18 is in a fully closed state, and the flow rate adjustment section 19 is in a fully open state. 2 bypass flow path (refrigerant pipe 120H) is used. The high-pressure gas refrigerant discharged from the compressor 11 radiates heat and liquefies and condenses by exchanging heat with a heat medium passing through a high-temperature heat exchanger 21 provided integrally with the condenser 12 in the condenser 12, It becomes a high-pressure liquid refrigerant. The high-pressure liquid refrigerant flowing out of the condenser 12 is depressurized and expanded by the expansion valve 13, becomes a low-pressure refrigerant, and flows into the evaporator 14.

The low-pressure refrigerant that has flowed into the evaporator 14 evaporates by exchanging heat with the heat medium passing through the low-temperature heat exchanger 31 that is provided integrally with the evaporator 14, and flows out of the evaporator 14 as a gas refrigerant. , flows through the accumulator 15 to the low pressure side flow path 16B of the internal heat exchanger 16. At this time, since the flow rate adjustment unit 19 is fully open, the high-pressure refrigerant that has passed through the condenser 12 does not flow into the high-pressure side flow path 16A of the internal heat exchanger 16. Therefore, the refrigerant that has exited the accumulator 15 passes through the low-pressure side flow path 16B of the internal heat exchanger 16 without undergoing heat exchange, and returns to the compressor 11.

(Refrigerant flow during heating operation when the outside air is extremely low temperature)
On the other hand, for example, in heating operation when the outside air is extremely low temperature, the refrigerant is circulated in the refrigerant circuit R as follows.
As shown in FIG. 3, in the refrigerant circuit R, the electronic expansion valve 18 is opened to use the first bypass flow path (refrigerant pipe 120G), and the flow rate adjustment section 19 is fully closed to use the second bypass flow path (refrigerant pipe 120G). Heat exchange between the high-pressure refrigerant and the low-pressure refrigerant is performed in the internal heat exchanger 16 without using the refrigerant pipe 120H). Note that, as described above, the opening degree of the flow rate adjustment section 19 is adjusted based on the state of the refrigerant at the outlet of the compressor 11 or the outlet of the accumulator 15, so the flow rate adjustment section 19 is not necessarily in a fully closed state.

As a result, a part of the high-pressure gas refrigerant discharged from the compressor 11 radiates heat by exchanging heat with the heat medium passing through the high-temperature heat exchanger 21 provided integrally with the condenser 12 in the condenser 12. It liquefies and condenses to become a high-pressure liquid refrigerant. The high-pressure liquid refrigerant flowing out of the condenser 12 passes through the high-pressure side flow path 16A of the internal heat exchanger 16, and exchanges heat with the low-pressure side refrigerant passing through the low-pressure side flow path 16B.

The refrigerant that has flowed out of the high-pressure side flow path 16A of the internal heat exchanger 16 is depressurized and expanded by the expansion valve 13, becomes a low-pressure refrigerant, and flows into the evaporator 14. The low-pressure refrigerant that has flown out of the evaporator 14 flows out of the evaporator 14 without exchanging heat with the heat medium that passes through the low-temperature heat exchanger 31 that is provided integrally with the evaporator 14, and merges from the first bypass flow path. The refrigerant flows into the accumulator 15 together with the refrigerant that has flowed into the section 122.

In addition, the remainder of the high-pressure gas refrigerant discharged from the compressor 11 flows through the first bypass flow path, is depressurized at the electronic expansion valve 18, and joins with the refrigerant that has exited the evaporator 14 at the confluence section 122 to form the accumulator 15. flows into. The low-pressure refrigerant separated into gas and liquid by the accumulator 15 passes through the low-pressure side passage 16B of the internal heat exchanger 16, exchanges heat with the high-pressure refrigerant passing through the high-pressure side passage 16A, and returns to the compressor 11.

(Flow of refrigerant during cooling operation)
For example, when performing cooling operation, the refrigerant is circulated in the refrigerant circuit R as follows.
As shown in FIG. 4, in the refrigerant circuit R, the electronic expansion valve 18 is fully closed and the first bypass flow path (refrigerant pipe 120G) is not used, and the flow rate adjustment section 19 is fully closed and the second bypass flow path (refrigerant pipe 120G) is not used. Heat exchange between the high-pressure refrigerant and the low-pressure refrigerant is performed in the internal heat exchanger 16 without using the refrigerant pipe 120H).

As a result, the high-pressure gas refrigerant discharged from the compressor 11 radiates heat and liquefies by exchanging heat with the heat medium passing through the high-temperature heat exchanger 21 provided integrally with the condenser 12 in the condenser 12. It condenses and becomes a high-pressure liquid refrigerant. The high-pressure liquid refrigerant flowing out of the condenser 12 passes through the high-pressure side flow path 16A of the internal heat exchanger 16, and exchanges heat with the low-pressure side refrigerant passing through the low-pressure side flow path 16B.

The refrigerant that has flowed out of the high-pressure side flow path 16A of the internal heat exchanger 16 is depressurized and expanded by the expansion valve 13, becomes a low-pressure refrigerant, and flows into the evaporator 14. The low-pressure refrigerant that has flown out of the evaporator 14 evaporates by exchanging heat with the heat medium that passes through the low-temperature heat exchanger 31 that is provided integrally with the evaporator 14, and flows out of the evaporator 14 as a gas refrigerant. It flows into the accumulator 15. The low-pressure refrigerant separated into gas and liquid by the accumulator 15 passes through the low-pressure side passage 16B of the internal heat exchanger 16, exchanges heat with the high-pressure refrigerant passing through the high-pressure side passage 16A, and returns to the compressor 11.

According to the refrigerant circuit configured in this way, during heating operation when the outside air is extremely low temperature, the first bypass flow path is used to transfer the high temperature and high pressure refrigerant discharged from the compressor 11 to the other heat exchanger. By returning the refrigerant to the upstream side of the accumulator 15 without passing it through, the density of the refrigerant sucked into the compressor 11 can be increased. Therefore, the heating capacity of the condenser 12 can be ensured without depending on outside air, and the heating capacity can be ensured.

Further, by flowing the refrigerant that has flowed out of the accumulator 15 into the low-pressure side channel 16B of the internal heat exchanger 16, the state of the refrigerant can be stabilized and liquid compression in the compressor 11 can be prevented.
In other words, when the second bypass flow path is used and the internal heat exchanger 16 does not perform heat exchange with the refrigerant passing through the low-temperature side flow path 16B, the low-pressure side flow path 16B of the internal heat exchanger 16 is Since the chamber can be a mixture of refrigerant and gas refrigerant, the state of the refrigerant can be stabilized and liquid compression in the compressor 11 can be suppressed.
On the other hand, when the refrigerant flows through the high-pressure side flow path 16A and exchanges heat with the refrigerant flowing through the low-pressure side flow path 16B, the state of the refrigerant can be further stabilized by heat exchange, and liquid compression can be further prevented.

Note that signs of liquid compression are monitored based on the discharge temperature of the compressor 11, and if signs of liquid compression are observed, the amount of refrigerant flowing into the high-pressure side flow path 16A of the internal heat exchanger 16 is increased. control the flow rate adjustment unit 19 so that the amount of refrigerant flowing into the high-pressure side flow path 16A of the internal heat exchanger 16 becomes small when there is no sign of liquid compression. The flow rate of the refrigerant flowing into the second bypass flow path and the high pressure side flow path 16A of the internal heat exchanger 16 is adjusted. Thereby, liquid compression in the compressor 11 can be more reliably prevented without reducing air conditioning efficiency.

In the examples shown in FIGS. 2 to 4, a case has been described in which the flow rate adjustment section 19 is fully closed or fully opened, but the flow rate adjustment section 19 can be adjusted as appropriate to improve air conditioning efficiency.
For example, when the flow rate of refrigerant flowing into the high-pressure side passage 16A of the internal heat exchanger 16 is small, the suction density of the refrigerant in the compressor 11 becomes large, the discharge temperature of the compressor 11 becomes low, and the inlet of the expansion valve 13 The temperature increases. On the other hand, when the flow rate of refrigerant flowing into the high pressure side flow path 16A of the internal heat exchanger 16 is large, the suction density of the refrigerant in the compressor 11 becomes small, the discharge temperature of the compressor 11 becomes high, and the inlet of the expansion valve 13 temperature becomes lower.

In the case of heating operation, when improving the heating capacity and air conditioning efficiency, it is determined which of the refrigerant suction density in the compressor 11 or the refrigerant discharge temperature in the compressor 11 makes a larger contribution, and the flow rate adjustment unit 19 control.

Furthermore, in the case of cooling operation, when improving the cooling capacity and air conditioning efficiency, it is determined which of the refrigerant suction density in the compressor 11 or the inlet temperature of the expansion valve 13 contributes more, and the flow rate adjustment unit 19 control.

When applying the refrigerant circuit R described above to a vehicle air conditioner, for example, the refrigerant circuit R may be configured to directly exchange heat between the refrigerant and the air supplied into the vehicle interior (Example 1), or After the refrigerant and another heat medium undergo heat exchange, the heat medium and the air supplied into the vehicle interior may be configured to exchange heat (Example 2).

(Example 1)
As shown in FIG. 5, the vehicle air conditioner 101 is configured to directly exchange heat between the refrigerant in the refrigerant circuit and the air supplied into the vehicle interior. The air conditioning unit 80 supplies temperature-controlled air into the vehicle interior through exchange.

In the example of FIG. 5, the condenser 12 and evaporator 14 of the refrigerant circuit R1 are arranged within the air flow passage 84 of the air conditioning unit 80. The condenser 12 includes an air heat exchanger provided integrally with the condenser 12, and is an indoor heat exchanger that radiates heat from the high-temperature, high-pressure refrigerant discharged from the compressor 11 to heat the air supplied into the vehicle interior. It becomes 4. The evaporator 14 includes an air heat exchanger provided integrally with the evaporator 14, and serves as a heat absorber 9 that cools the air supplied into the vehicle interior by causing the refrigerant to absorb heat from inside and outside the vehicle interior during cooling and dehumidification. .

In addition, the refrigerant circuit R1 in FIG. 5 includes an outdoor expansion valve 6 that depressurizes and expands the refrigerant during heating, and functions as a radiator that radiates heat from the refrigerant during cooling, and as an evaporator that absorbs heat from the refrigerant during heating. An outdoor heat exchanger 7 for exchanging heat with outside air, a refrigerant heat medium heat exchanger 64 for exchanging heat between the refrigerant in the refrigerant circuit R1 and another heat medium, and a refrigerant heat medium heat exchanger An expansion valve 72 is provided to reduce the pressure of the refrigerant flowing into the refrigerant 64 .

In the vehicle air conditioner 101 configured in this way, when performing heating operation at low outside temperatures using the first bypass flow path, a control unit (not shown) controls the outdoor expansion valve 6, the expansion valve 13, and the solenoid valve. 23 is closed, the electromagnetic valve 22 and expansion valve 72 are opened, and the electronic expansion valve 18 is opened. As a result, a first bypass flow path is formed, and the refrigerant circulates as shown in FIG. At this time, the indoor blower 87 is operated to introduce air from the suction port 83, and the air mix damper 89 adjusts the ratio of the air blown out from the indoor blower 87 to the indoor heat exchanger 4. .

As shown in FIG. 6, a portion of the refrigerant discharged from the compressor 11 flows into the indoor heat exchanger 4. The high-temperature, high-pressure gas refrigerant that has flowed into the indoor heat exchanger 4 exchanges heat with the air in the air flow passage 84, so that the air in the air flow passage 84 is heated by the refrigerant, and the heated air is discharged from the outlet. The air is blown into the passenger compartment to heat the vehicle. The refrigerant that has undergone heat exchange in the indoor heat exchanger 4 loses heat to the air, is cooled, and condenses.

After the condensed refrigerant leaves the indoor heat exchanger 4, part of it flows into the high-pressure side flow path 16A of the internal heat exchanger 16, and the rest flows into the second bypass flow path. The refrigerant passing through the high-pressure side flow path 16A exchanges heat with the refrigerant passing through the low-pressure side flow path 16B, and heads toward the merging portion 124. The refrigerant that has flowed into the second bypass flow path and passed through the flow rate adjustment section 19 and the refrigerant that has flowed into the high-pressure side flow path 16A of the internal heat exchanger 16 join together at the confluence section 124 and pass through the expansion valve 72 to generate heat from the refrigerant heat medium. It passes through an exchanger 64. The refrigerant expands in the expansion valve 72 to become low temperature and low pressure, passes through the refrigerant heat medium heat exchanger 64 without exchanging heat with the heat medium, and flows into the accumulator 15.

On the other hand, the high-temperature, high-pressure gas refrigerant discharged from the compressor 11 flows through the first bypass flow path, is expanded by the electronic expansion valve 18, and flows into the accumulator 15 again. That is, the accumulator 15 contains refrigerant that has been liquefied through the indoor heat exchanger 4, the high-pressure side channel 16A of the internal heat exchanger, and the expansion valve 72, and the refrigerant that has been compressed by the compressor 11 and then expanded by the electronic expansion valve 18. The refrigerant will flow in. The refrigerant that has flowed into the accumulator 15 is separated into gas and liquid, and then is sucked into the compressor 11 as a gas refrigerant while passing through the low-pressure side passage 16B of the internal heat exchanger 16 and repeats the circulation.

(Example 2)
As shown in FIG. 7, the vehicle air conditioner 102 is configured to exchange heat between the refrigerant in the refrigerant circuit and another heat medium, and then exchange heat between the heat medium and air supplied into the vehicle interior. , a refrigerant circuit R2 serving as a heat source, a heat medium circuit 10 that circulates a heat medium whose temperature is controlled by heat exchange with the refrigerant, and air whose temperature is controlled by the heat medium circulating in the heat medium circuit 10 is supplied into the vehicle interior. An air conditioning unit 80 is provided.

The heat medium circuit 10 includes a high temperature heat medium flow path 20, a low temperature heat medium flow path 30, a temperature control target heat medium flow path 40, a tank 50, a first flow path switching section V1, a second flow path switching section V2, and a second flow path switching section V2. It is configured to include a three-channel switching section V3.

The high temperature heat medium flow path 20 includes a high temperature heat exchanger 21 which is a refrigerant heat medium heat exchanger that is integrated with the condenser 12 in the refrigerant circuit R2 and performs heat exchange between the heat medium and the refrigerant. In the high-temperature heat medium flow path 20, the heat medium pumped by the first pump P1 becomes high in temperature due to heat radiation of the refrigerant in the condenser 12 in the refrigerant circuit R2 while passing through the high-temperature heat exchanger 21, and circulates.

The low-temperature heat medium flow path 30 includes a low-temperature heat exchanger 31 that is integrated with the evaporator 14 in the refrigerant circuit R2 and performs heat exchange between the heat medium and the refrigerant. However, while passing through the low-temperature heat exchanger 31, the temperature becomes low due to heat absorption by the refrigerant in the evaporator 14 in the refrigerant circuit R2, and the refrigerant circulates.

The temperature-controlled heat medium flow path 40 includes a battery heat exchanger 41 that controls the temperature of the battery in an electric vehicle, a motor heat exchanger 42 that controls the temperature of the driving motor, and an inverter that controls the temperature of the inverter. A PCU heat exchanger 44 for controlling the temperature of the power control unit, and an outdoor heat exchanger 45 are provided. In the temperature-controlled heat medium flow path 40, the heat medium is pumped by the third pump P3.

The tank 50 has an inlet 52 connected to the high temperature heat medium flow path 20, an inlet 54 connected to the temperature controlled heat medium flow path 40, and an outlet 53 connected to the low temperature heat medium flow path 30. It is equipped with
The high temperature heat medium flow path 20 is provided with a connection portion 28 connected to the inlet 52 on the heat medium upstream side of the first pump P1. The temperature-controlled heat medium flow path 40 is provided with a connecting portion 48 connected to the inlet 54 on the downstream side of the heat medium of each temperature-controlled heat exchanger. The low-temperature heat medium flow path 30 is provided with a connection portion 38 connected to the outlet 53 on the heat medium upstream side of the second pump P2.

That is, as shown in FIG. 7, the tank 50 is connected to the upstream side of the first pump P1 in the high-temperature heat medium flow path 20 through an inlet 52, and is connected to the upstream side of the first pump P1 in the temperature-controlled heat medium flow path 40 through an inflow port 54. It is connected to the heat medium downstream side of the heat exchanger 42 and connected to the heat medium upstream side of the second pump P2 in the low temperature heat medium flow path 30 through the outlet 53.

Additionally, a relief valve 57 is provided in a path from the connection portion 28 to the inlet 52 of the tank 50. As a result, when the heat medium expands due to an increase in the temperature of the heat medium circulating in the high temperature heat medium flow path 20 and the amount of heat medium becomes large with respect to the circuit capacity of the high temperature heat medium flow path 20, the relief valve 57 is in an open state, and the heat medium flows from the high temperature heat medium flow path 20 into the tank 50 via the inlet 52.

Similarly, a relief valve 58 is provided in a path from the connection portion 48 to the inlet 54 of the tank 50. As a result, when the heat medium expands due to an increase in the temperature of the heat medium circulating in the heat medium flow path 40 to be temperature controlled, and the amount of heat medium becomes large with respect to the circuit capacity of the heat medium flow path 40 to be temperature controlled. , the relief valve 58 is opened, and the heat medium flows from the temperature-controlled heat medium flow path 40 into the tank 50 via the inlet 54.

On the other hand, when the temperature of the heat medium circulating in the low temperature heat medium flow path 30 decreases and the heat medium contracts, the heat medium stored in the tank 50 flows out from the outlet 53 and the low temperature heat medium flows through the connection part 38. Flows into channel 30.

In addition, as the heat medium circulating in the heat medium circuit 10, water without additives, water mixed with additives such as antifreeze agents and preservatives, or liquid heat medium such as oil may be used. can do.

The air conditioning unit 80 includes an inlet 83 that introduces air (outside air or indoor air), an air flow passage 84 through which the air sucked from the inlet 83 passes, and an air flow passage 84 that is provided in the air flow passage 84 and circulates through the heat medium circuit 10. A first heat exchanger 81 and a second heat exchanger 82 are provided, through which a heat medium flows.

In the air conditioning unit 80, the air introduced into the air flow path 84 from the suction port 83 is ventilated through the first heat exchanger 81 and the second heat exchanger 82, and the air is passed through the first heat exchanger 81 and the second heat exchanger 82. Temperature-controlled air is blown into the vehicle interior by exchanging heat with the heat medium.

In the vehicle air conditioner 102 configured as described above, the control unit (not shown) adjusts the opening degrees of the flow rate adjustment unit 19 and the electronic expansion valve 18 to control the flow to the first bypass flow path and the second bypass flow path. Control the flow rate of refrigerant. In addition, in the heat medium circuit 10, by controlling the first flow path switching section V1, the second flow path switching section V2, and the third flow path switching section V3, the high temperature heat medium flow path 20 of the heat medium circuit 10, the low temperature The connection state of the heat medium flow path 30 and the temperature-controlled heat medium flow path 40 can be changed as appropriate.

Hereinafter, in the vehicle air conditioner 102 configured as described above, the rotation speed of the compressor 11 and the like are appropriately controlled by a control unit (not shown), while utilizing the heat radiation of the condenser 12 and the heat absorption of the evaporator 14. It adjusts the air supplied to the vehicle interior to a target temperature and air-conditions the vehicle interior. In particular, when performing heating operation at low outside temperatures, in the refrigerant circuit R2, the electronic expansion valve 18 is opened to form a first bypass flow path, and the flow rate adjustment section 19 is closed to close the second bypass flow path. do. In the refrigerant circuit R2, the refrigerant circulates in the same manner as in the refrigerant circuit R of FIG.

That is, in the refrigerant circuit R2, the electronic expansion valve 18 is fully open and the first bypass flow path is used, and the flow rate adjustment section 19 is fully closed and the second bypass flow path is not used, and the internal heat exchanger 16 is Heat exchange is performed between the high pressure refrigerant and the low pressure refrigerant.

As a result, a part of the high-pressure gas refrigerant discharged from the compressor 11 radiates heat by exchanging heat with the heat medium passing through the high-temperature heat exchanger 21 provided integrally with the condenser 12 in the condenser 12. It liquefies and condenses to become a high-pressure liquid refrigerant. The high-pressure liquid refrigerant flowing out of the condenser 12 passes through the high-pressure side flow path 16A of the internal heat exchanger 16, and exchanges heat with the low-pressure side refrigerant passing through the low-pressure side flow path 16B.

The refrigerant that has flowed out of the high-pressure side flow path 16A of the internal heat exchanger 16 is depressurized and expanded by the expansion valve 13, becomes a low-pressure refrigerant, and flows into the evaporator 14. The low-pressure refrigerant that has flown out of the evaporator 14 flows out of the evaporator 14 without exchanging heat with the heat medium that passes through the low-temperature heat exchanger 31 that is provided integrally with the evaporator 14, and merges from the first bypass flow path. The refrigerant flows into the accumulator 15 together with the refrigerant that has flowed into the section 122.

In addition, the remainder of the high-pressure gas refrigerant discharged from the compressor 11 flows through the first bypass flow path, is depressurized at the electronic expansion valve 18, and joins with the refrigerant that has exited the evaporator 14 at the confluence section 122 to form the accumulator 15. flows into. The low-pressure refrigerant separated into gas and liquid by the accumulator 15 passes through the low-pressure side passage 16B of the internal heat exchanger 16, exchanges heat with the high-pressure refrigerant passing through the high-pressure side passage 16A, and returns to the compressor 11.

On the other hand, in the heat medium circuit 10, the heat medium circulates as follows (FIG. 8).

In Fig. 8, regarding the flow of the heat medium, the piping in which the high temperature heat medium circulates is shown as a solid black line, the piping in which the heat medium in the intermediate temperature range between high and low temperatures circulates is shown as a two-dot chain line, and the heat medium The broken lines indicate piping in which water does not circulate.
The control section controls the first flow path switching section V1, the second flow path switching section V2, and the third flow path switching section V3 to circulate the heat medium in the heat medium circuit 10 as follows.

The heat medium passed through the high temperature heat exchanger 21 and heated is circulated to the high temperature heat medium flow path 20. That is, the heat medium heated by passing through the high-temperature heat exchanger 21 flows into the second heat exchanger 82 via the first flow path switching section V1, and after exchanging heat with the air passing through the air conditioning unit 80. , flows into the first heat exchanger 81 via the first flow path switching section V1, and exchanges heat with the air passing through the air conditioning unit 80. The heat medium that has exited the first heat exchanger 81 is repeatedly circulated back to the high temperature heat exchanger 21 by the first pump P1 via the first flow path switching section V1 and the third flow path switching section V3. Thereby, the vehicle interior can be heated.

In the temperature-controlled heat medium flow path 40, the battery heat exchanger 41 is connected to the motor heat exchanger 42, the inverter heat exchanger 43, and the PCU heat exchanger 44 via the second flow path switching section V2. , the temperature of each on-vehicle device is adjusted by circulating the heat medium through the battery heat exchanger 41, motor heat exchanger 42, inverter heat exchanger 43, and PCU heat exchanger 44 while being pumped by the third pump P3. Make adjustments.

Furthermore, as described above, the control unit controls the first flow path switching unit V1 to be switched so that the heat medium that has flowed through the second heat exchanger 82 also flows through the first heat exchanger 81. That is, the first flow path switching unit V1 can be switched so that the heated or cooled heat medium flows through both of the plurality of first heat exchangers 81 and second heat exchangers 82 included in the air conditioning unit 80. Therefore, it is possible to improve the air conditioning capacity when executing the heating mode or the cooling mode.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments or examples, and the design may be modified within the scope of the gist of the present invention. Even if there are changes, they are included in the present invention. In addition, the above-described embodiments can be combined by using each other's technologies unless there is a particular contradiction or problem in their purpose, structure, etc.

4: indoor heat exchanger, 6: outdoor expansion valve, 7: outdoor heat exchanger, 9: heat absorber 10: heat medium circuit, 11: compressor, 12: condenser, 13: expansion valve, 14: evaporator, 15: Accumulator, 16: Internal heat exchanger, 16A: High pressure side flow path, 16B: Low pressure side flow path 18: Electronic expansion valve, 19: Flow rate adjustment section, 20: High temperature heat medium flow path, 21: High temperature heat exchanger 22, 23: Solenoid valve, 30: Low temperature heat medium flow path, 31: Low temperature heat exchanger 40: Temperature control target heat medium flow path, 64: Refrigerant heat medium heat exchanger, 72: Expansion valve, 80: Air conditioning unit 101 , 102: Vehicle air conditioner R: Refrigerant circuit, R1: Refrigerant circuit, R2: Refrigerant circuit

Claims (6)

1. A vehicle air conditioner comprising a refrigerant circuit that sequentially connects a compressor, a condenser, an expansion section, an evaporator, and a gas-liquid separation section through refrigerant piping and circulates the refrigerant,
   The refrigerant circuit is
   a first bypass flow path that causes the refrigerant discharged from the compressor to flow into the inlet side of the gas-liquid separation section;
   An air conditioner for a vehicle, comprising: an internal heat exchanger that exchanges heat between a refrigerant flowing from the gas-liquid separation section to the compressor and a refrigerant flowing out from the condenser.
2. The vehicle air conditioner according to claim 1, further comprising a second bypass passage that causes the refrigerant flowing out of the condenser to flow into the evaporator, bypassing the internal heat exchanger.
3. The vehicle air conditioner according to claim 2, wherein the second bypass flow path has a flow rate adjustment section that adjusts the flow rate of the refrigerant passing through the second bypass flow path.
4. The vehicle according to claim 3, wherein the flow rate adjustment unit adjusts the flow rate of the refrigerant passing through the second bypass flow path based on the degree of superheating estimated from the pressure and temperature of the refrigerant discharged from the compressor. Air conditioner.
5. The vehicle air conditioner according to claim 4, wherein the flow rate adjustment unit reduces the flow rate of the refrigerant flowing into the second bypass flow path when the degree of superheat is less than or equal to a threshold value.
6. The vehicle air conditioner according to claim 3, wherein the flow rate adjustment unit adjusts the flow rate of the refrigerant passing through the second bypass flow path based on the suction dryness estimated from the temperature of the refrigerant discharged from the compressor. Device.