Vehicular heat management system

Abstract

[Problem] To provide heating in a low-temperature environment without using an electric heater or the like. [Solution] When a heat medium–heating electric heater 83 cannot be used in a low-temperature environment and it has been determined that there is frost on an outdoor heat exchanger 42, the outside air temperature is above a prescribed condition, and the demand for heating is high, a control device 90 selects to not perform a heat exchange at a high-temperature-side heat exchanger 22 and to perform a hot gas cycle–based defrosting and heating operation in which defrosting is performed by release of heat from a refrigerant at a first evaporator 14 to heat a heat medium flowing through a first low-temperature-side heat exchanger 24 and passage of the heated heat medium through the outdoor heat exchanger 42 and heating is performed by release of heat from a refrigerant at a second evaporator 17 to heat a heat medium flowing through a second low-temperature-side heat exchanger 27 and passage of the heated heat medium through a cooler core 72.

Description

Vehicle Thermal Management System

[0001] The present invention relates to a vehicle thermal management system.

[0002] In order to perform air conditioning in a vehicle and temperature adjustment of in-vehicle devices, a system is known that includes a refrigerant circuit that functions as a heat pump and a heat medium circuit in which a heat medium that exchanges heat with the refrigerant of the refrigerant circuit is provided to carry heat to each part. In such a system, various measures have been taken for heating operation when the refrigerant circuit cannot function as a heat pump due to insufficient heat source in a low-temperature environment. For example, Patent Document 1 discloses a technique in which a heater core is heated by waste heat from a motor or the like to perform heating, when the heater core is warmed, the low-temperature side heat exchanger of the refrigerant circuit is warmed, and when the low-temperature side heat exchanger is warmed, the heat pump is operated. According to this method, there is no need to separately prepare a heat source such as an electric heater for warming the low-temperature side heat exchanger. In such a system, there can be various methods of performing heating in a low-temperature environment without using an electric heater or the like.

[0003] Japanese Unexamined Patent Application Publication No. 2021-024364

[0004] An object of the present invention is to provide a vehicle thermal management system that can perform heating in a low-temperature environment without using an electric heater or the like.

[0005] According to one aspect of the present invention, a vehicle thermal management system includes a refrigerant circuit including a compressor, a condenser for a high-temperature side heat exchanger, a depressurizing device, and an evaporator for a low-temperature side heat exchanger; a heat transfer medium circuit configured to carry a heat transfer medium that exchanges heat with the refrigerant flowing through the refrigerant circuit; and a control device configured to control the operation of the refrigerant circuit and the heat transfer medium circuit. The heat transfer medium circuit includes a heater core for heating that can be connected to the high-temperature side heat exchanger, a cooler core for cooling that can be connected to the low-temperature side heat exchanger, a heat transfer medium heating electric heater configured to heat the heat transfer medium flowing through the low-temperature side heat exchanger, an outdoor heat exchanger configured to exchange heat between the heat transfer medium and the outside air, and a target equipment temperature control unit configured to control the temperature of equipment to be temperature controlled using the heat transfer medium. The control device is configured to perform defrosting operations using a hot gas cycle when the electric heater for heating the heat transfer medium cannot be used in a low-temperature environment, and it is determined that there is frost on the outdoor heat exchanger, the outside air temperature is higher than predetermined conditions, and the heating requirement is low; to perform heating operations using a hot gas cycle when it is determined that the outside air temperature is lower than predetermined conditions; and to perform heating and defrosting operations using a hot gas cycle when it is determined that there is frost on the outdoor heat exchanger, the outside air temperature is higher than predetermined conditions, and the heating requirement is also high. The defrosting operation using a hot gas cycle is an operation in which, without performing heat exchange in the high-temperature side heat exchanger, the refrigerant releases heat in the evaporator to heat the heat transfer medium flowing through the low-temperature side heat exchanger, and the heated heat transfer medium is flowed to the outdoor heat exchanger to perform defrosting. The heating operation using the hot gas cycle is an operation in which, without performing heat exchange in the high-temperature side heat exchanger, the refrigerant releases heat in the evaporator to heat the heat transfer medium flowing through the low-temperature side heat exchanger, and the heated heat transfer medium is then flowed to the cooler core to perform heating. The heating and defrosting operation using the hot gas cycle is an operation in which, without performing heat exchange in the high-temperature side heat exchanger, the refrigerant releases heat in the evaporator to heat the heat transfer medium flowing through the low-temperature side heat exchanger, the heated heat transfer medium is then flowed to the cooler core to perform heating, and the heated heat transfer medium is then flowed to the outdoor heat exchanger to perform defrosting.

[0006] According to the present invention, a vehicle thermal management system can be provided that can perform heating in low-temperature environments without using electric heaters or the like.

[0007] Figure 1 is a schematic diagram showing an example configuration of a vehicle thermal management system according to one embodiment, and is a diagram showing an operating mode that performs defrosting and heating of the outdoor heat exchanger in a low-temperature environment. Figure 2 is a schematic diagram for explaining defrosting operation, which performs defrosting of the outdoor heat exchanger when the heat transfer medium heating electric heater cannot be used in a low-temperature environment. Figure 3 is a schematic diagram for explaining heating operation when the heat transfer medium heating electric heater cannot be used in a low-temperature environment. Figure 4 is a schematic diagram for explaining operation that performs heating and defrosting operation simultaneously when the heat transfer medium heating electric heater cannot be used in a low-temperature environment. Figure 5 is a schematic diagram for explaining heating operation when the heat transfer medium heating electric heater cannot be used in a low-temperature environment. Figure 6 is a flowchart showing an example of the operation of the control device when the heat transfer medium heating electric heater cannot be used. Figure 7 is a diagram showing an example of a method for determining the operating mode. Figure 8 is a schematic diagram showing an example configuration of a vehicle thermal management system according to a first modified example. Figure 9 is a schematic diagram showing an example configuration of a vehicle thermal management system according to a second modified example. Figure 10 is a schematic diagram showing an example configuration of a vehicle thermal management system according to the third modified example. Figure 11 is a schematic diagram showing an example configuration of a vehicle thermal management system according to the fourth modified example. Figure 12 is a schematic diagram showing an example configuration of a vehicle thermal management system according to the fifth modified example.

[0008] [Configuration of the Vehicle Thermal Management System] One embodiment will be described with reference to the drawings. Figure 1 is a schematic diagram showing an example of the configuration of the vehicle thermal management system 1 according to this embodiment. The vehicle thermal management system 1 is installed in a vehicle such as an electric vehicle. The vehicle thermal management system 1 has the function of adjusting the temperature, humidity, etc. of the air inside the vehicle. The vehicle thermal management system 1 is a thermal management system configured to be able to adjust not only the temperature inside the vehicle, but also the temperature of the motor and battery installed in the vehicle.

[0009] The vehicle thermal management system 1 comprises a refrigerant circuit 10, a first heat transfer medium circuit 30, and a second heat transfer medium circuit 60. The vehicle thermal management system 1 also includes a control device 90 that controls the operation of each part of the vehicle thermal management system 1, and various sensors (not shown). The control device 90 may include various integrated circuits for calculation, storage, and other functions. The operation of the control device 90 may be performed according to programs stored in the various integrated circuits as hardware or software.

[0010] The first heat transfer fluid circuit 30 and the second heat transfer fluid circuit 60 are circuits through which a heat transfer fluid flows to exchange heat with the refrigerant circuit 10, and the heat transfer fluid carries the necessary heat to various parts of the vehicle. The first heat transfer fluid circuit 30 is configured to switch circuits according to various operations and can take on various states. Figure 1 shows, as an example, an operating mode that performs defrosting and heating of the outdoor heat exchanger 42 in a low-temperature environment.

[0011] The refrigerant circuit 10 includes a compressor 11, a condenser 12 of the high-temperature side heat exchanger 22, a pressure reducing device, an evaporator of the low-temperature side heat exchanger, and an accumulator 19, all arranged to allow the refrigerant to circulate. In this embodiment, two sets of pressure reducing devices and evaporators are provided in parallel. Specifically, one of two parallel flow paths, which branch off at a first branching point 111 downstream of the condenser 12 and merge at a first confluence point 121 upstream of the accumulator 19, is provided with a first pressure reducing device 13, a first evaporator 14 of the first low-temperature side heat exchanger 24, and a first check valve 15, while the other is provided with a second pressure reducing device 16, a second evaporator 17 of the second low-temperature side heat exchanger 27, and a second check valve 18.

[0012] The refrigerant is not limited to this, but for example, propane R290 refrigerant may be used. The refrigerant circuit 10 is configured to function as a refrigerator or a heat pump. That is, the refrigerant circulating in the refrigerant circuit 10 is compressed, condensed, expanded, and evaporated in the compressor 11, condenser 12, first pressure reducing device 13 or second pressure reducing device 16, and first evaporator 14 or second evaporator 17, respectively, and these processes are repeated.

[0013] In the high-temperature heat exchanger 22 or the first low-temperature heat exchanger 24, heat exchange takes place between the refrigerant in the refrigerant circuit 10 and the heat transfer medium in the first heat transfer medium circuit 30. Similarly, in the second low-temperature heat exchanger 27, heat exchange takes place between the refrigerant in the refrigerant circuit 10 and the heat transfer medium in the second heat transfer medium circuit 60. The heat transfer medium is a fluid, such as coolant. The heat transfer medium circulates throughout the vehicle, heating or cooling each part, and transferring heat from one part to another.

[0014] The vehicle thermal management system 1 includes an HVAC (Heating, Ventilation, and Air Conditioning) unit 70. Inside the HVAC unit 70 are a heater core 71 which constitutes part of the first heat transfer medium circuit 30 and a cooler core 72 which constitutes part of the second heat transfer medium circuit 60.

[0015] The heater core 71 of the first heat transfer medium circuit 30 is configured to circulate a heat transfer medium heated in the high-temperature side heat exchanger 22. The heater core 71 is configured to heat the air supplied to the vehicle interior. The heater core 71 can be used when heating the vehicle interior. The cooler core 72 of the second heat transfer medium circuit 60 is configured to circulate a heat transfer medium cooled in the second low-temperature side heat exchanger 27. The cooler core 72 is configured to cool the air supplied to the vehicle interior. The cooler core 72 can be used when cooling the vehicle interior.

[0016] The cooler core 72 is located upstream of the air passage 75 of the HVAC unit 70, and the heater core 71 is located downstream of the air passage 75 of the HVAC unit 70. The blower 76 of the HVAC unit 70 supplies air taken in from inside and outside the vehicle interior through the air passage 75 into the vehicle interior. The air supplied to the vehicle interior is heated by passing through the heater core 71 or cooled by passing through the cooler core 72 in the HVAC unit 70, thereby heating or cooling the vehicle interior.

[0017] The first heat transfer medium circuit 30 includes an outdoor heat exchanger 42, a motor temperature control unit 81, a battery temperature control unit 82, and a heat transfer medium heating electric heater 83. The outdoor heat exchanger 42 is configured so that the heat transfer medium flowing through it can exchange heat with the outside air. In the outdoor heat exchanger 42, the heat transfer medium can release heat to the outside air or absorb heat from the outside air. The motor temperature control unit 81 is configured so that the heat transfer medium flowing through it can exchange heat with the motor. The motor is heated or cooled by the heat transfer medium flowing through the motor temperature control unit 81. The battery temperature control unit 82 is configured so that the heat transfer medium flowing through it can exchange heat with the battery. The battery is heated or cooled by the heat transfer medium flowing through the battery temperature control unit 82. Note that a configuration similar to that of the battery temperature control unit 82 can be applied not only to batteries but also to on-board equipment temperature control units for temperature control of other on-board equipment that similarly requires temperature control. Thus, the motor and battery are temperature-controlled devices, and the motor temperature control unit 81 and battery temperature control unit 82 are temperature-controlled devices configured to control the temperature of the temperature-controlled devices. The heat transfer medium heating electric heater 83 is configured to heat the heat transfer medium flowing through the heat transfer medium heating electric heater 83 with an electric heater. The heat transfer medium heating electric heater 83 is arranged in parallel with the battery temperature control unit 82.

[0018] Each component, such as the heater core 71, outdoor heat exchanger 42, motor temperature control unit 81, battery temperature control unit 82, and heat transfer medium heating electric heater 83, is connected to the flow path of the heat transfer medium in the first heat transfer medium circuit 30. The flow path of the first heat transfer medium circuit 30 is provided with a plurality of flow path switching means. In this embodiment, the flow path switching means includes a six-way valve 44. The flow path switching means also includes flow path switching units such as a first three-way valve 32, a second three-way valve 33, a third three-way valve 53, and a fourth three-way valve 54. By switching the connection of each flow path using these flow path switching means, the first heat transfer medium circuit 30 can form various circulation circuits.

[0019] Furthermore, the first heat transfer medium circuit 30 is equipped with multiple pumps for circulating the heat transfer medium through the flow path. Specifically, the first heat transfer medium circuit 30 includes a first pump 31 provided to circulate the heat transfer medium heated in the high-temperature side heat exchanger 22 to the heater core 71, etc., and second pumps 51 and third pumps 52 provided to circulate the heat transfer medium cooled in the first low-temperature side heat exchanger 24 to various parts. Through their operation, these pumps can circulate the heat transfer medium in the circulation circuit formed in the first heat transfer medium circuit 30. In addition, upstream of the first pump 31, the second pump 51, and the third pump 52, a first tank 34, a second tank 56, and a third tank 57 are provided in parallel with the flow path, respectively, in order to adjust the amount of heat transfer medium circulated according to the volume which may vary depending on the flow path. A third check valve 55 is provided upstream of the third tank 57. In this example, by providing two pumps, a second pump 51 and a third pump 52, the battery temperature control unit 82 for the battery, which requires precise temperature control, can be separated from the rest of the unit.

[0020] The cooler core 72 is connected to the flow path through which the heat transfer medium of the second heat transfer circuit 60 flows. The second heat transfer circuit 60 forms a circulation path. The second heat transfer circuit 60 is equipped with a fourth pump 61 and a fourth tank 62. The heat transfer medium discharged from the fourth pump 61 flows through the second low-temperature heat exchanger 27 and the cooler core 72 in that order, and then returns to the fourth pump 61.

[0021] [Regarding heating and defrosting operations of outdoor heat exchangers in low-temperature environments] Figure 1 shows an example of the state during heating and defrosting operations of outdoor heat exchangers in low-temperature environments, such as below -10°C. Due to the low temperature, frost has formed on the outdoor heat exchanger 42, but defrosting will allow the heat absorbed from the outside air to be used for heating, so the defrosting operation is performed. Also, because the heat source is limited at low temperatures, the heat transfer medium heating electric heater 83 is used as the heat source. The operation in this case will be explained below.

[0022] In the refrigerant circuit 10, the expansion valve of the second pressure reducing device 16 is fully closed, and the refrigerant does not pass through the second evaporator 17. On the other hand, the opening degree of the expansion valve of the first pressure reducing device 13 is adjusted based on the outlet subcool of the condenser 12, and the refrigerant passes through the first evaporator 14. The rotational speed of the compressor 11 is adjusted based on the temperature of the heat transfer medium at the outlet of the high-temperature side heat exchanger 22, the temperature of the heat transfer medium at the outlet of the heater core 71, the temperature of the heat transfer medium at the inlet of the outdoor heat exchanger 42, etc.

[0023] In the refrigerant circuit 10, the refrigerant is compressed into a high-temperature, high-pressure gas by the compressor 11, condenses and releases heat in the condenser 12 of the high-temperature side heat exchanger 22 to become a high-temperature, high-pressure liquid, expands in the first depressurization device 13 to become a low-pressure gas-liquid two-phase state, evaporates and absorbs heat in the first low-temperature side heat exchanger 24 to become a low-temperature, low-pressure gas, and is sent back to the compressor 11 via the accumulator 19.

[0024] At this time, the fourth pump 61 is stopped, and the heat transfer medium is not circulating in the second heat transfer medium circuit 60. On the other hand, in the high-temperature side heat transfer medium circuit of the first heat transfer medium circuit 30, the first pump 31 operates and sends the heat transfer medium to the high-temperature side heat exchanger 22. The heat transfer medium heated in the high-temperature side heat exchanger 22 is sent to the heater core 71 via the first three-way valve 32. In the HVAC unit 70, air is sent to the heater core 71 by the blower 76. Heat exchange takes place in the heater core 71 through which the high-temperature heat transfer medium flows, heating the air, and the warmed air is sent into the vehicle interior. Heating is performed in this manner. The heat transfer medium that has passed through the heater core 71 returns to the first pump 31 via the second junction 321.

[0025] Furthermore, the heat transfer medium heated in the high-temperature heat exchanger 22 is sent to the outdoor heat exchanger 42 via the first three-way valve 32 and the third junction 322. At this time, the shutter of the outdoor heat exchanger 42 is closed and the fan that blows air to the outdoor heat exchanger 42 is stopped. The outdoor heat exchanger 42 is defrosted as the high-temperature heat transfer medium passes through it. The heat transfer medium that has passed through the outdoor heat exchanger 42 returns to the first pump 31 via the six-way valve 44, the second three-way valve 33 and the second junction 321.

[0026] Furthermore, in the low-temperature side heat transfer circuit of the first heat transfer circuit 30, the third pump 52 is stopped, while the second pump 51 is operating. The second pump 51 sends the heat transfer medium to the first low-temperature side heat exchanger 24. The low-temperature heat transfer medium, which has released heat in the first low-temperature side heat exchanger 24 and supplied heat to the refrigerant in the refrigerant circuit 10, is sent to the heat transfer medium heating electric heater 83 via the third three-way valve 53, the fourth junction 521, the six-way valve 44, and the fourth three-way valve 54. The heat transfer medium is heated by the heat transfer medium heating electric heater 83, passes through the fifth junction 522, the second branch 511, and the sixth junction 523, passes through the motor temperature control unit 81, and returns to the second pump 51.

[0027] The vehicle thermal management system 1 generally operates the heat transfer medium heating electric heater 83 as a low-temperature heat source, as a heat pump cycle in the refrigerant circuit 10, and supplies heat to the heater core 71 and the outdoor heat exchanger 42.

[0028] Furthermore, once the outdoor heat exchanger 42 has been sufficiently defrosted, the outdoor heat exchanger 42 can be used to absorb heat from the outside air, and the outside air can be used as a heat source to heat the inside of the vehicle.

[0029] [Operation in Low-Temperature Environments When the Heat Transfer Medium Heating Electric Heater is Unavailable] As mentioned above, in low-temperature environments, the vehicle's thermal management system 1 uses the heat transfer medium heating electric heater 83 as a heat source for defrosting and heating operations. Suppose that, in a low-temperature environment, the heat transfer medium heating electric heater 83 becomes unusable due to a malfunction or other reason. In this case, the vehicle's thermal management system 1 loses its low-temperature heat source, and the refrigerant circuit 10 is unable to realize a heat pump cycle. In such cases, the refrigerant circuit 10 operates in an operating mode called a hot gas cycle or triangular cycle. Here, we will explain the operation of the vehicle's thermal management system 1 when the heat transfer medium heating electric heater 83 cannot be used as a low-temperature heat source, and when defrosting and heating operations are required in a low-temperature environment.

[0030] (1) Diagram 2 of the defrosting operation using the hot gas cycle is a schematic diagram for explaining the defrosting operation of the outdoor heat exchanger 42 when the heat transfer medium heating electric heater 83 cannot be used in a low-temperature environment. This operation is performed when, once the defrosting of the outdoor heat exchanger 42 is complete, the heat pump cycle of the refrigerant circuit 10 can be realized using the outside air as a low-temperature heat source by absorbing heat from the outside air using the outdoor heat exchanger 42, and heating can be performed by absorbing heat from the outside air.

[0031] In this state, the first pump 31 is stopped in the high-temperature side heat transfer medium circuit of the first heat transfer medium circuit 30, and no heat exchange takes place in the high-temperature side heat exchanger 22. Also, the fourth pump 61 is stopped, the heat transfer medium in the second heat transfer medium circuit 60 does not circulate, and no heat exchange takes place in the second low-temperature side heat exchanger 27. On the other hand, in the low-temperature side heat transfer medium circuit of the first heat transfer medium circuit 30, the second pump 51 is operating, and heat exchange takes place in the first low-temperature side heat exchanger 24.

[0032] In this operation, the refrigerant circuit 10 operates in a mode called a hot gas cycle or triangular cycle, in which heat is not dissipated in the condenser 12 of the high-temperature heat exchanger 22, but is dissipated in the first evaporator 14 of the first low-temperature heat exchanger 24. In the refrigerant circuit 10, the expansion valve of the second pressure reducing device 16 is fully closed, and the refrigerant does not pass through the second evaporator 17. On the other hand, the expansion valve of the first pressure reducing device 13 is open, and the refrigerant passes through the first evaporator 14. The rotational speed of the compressor 11 is adjusted based on the temperature of the heat transfer medium at the outlet of the first low-temperature heat exchanger 24. As a result, in the refrigerant circuit 10, the refrigerant is compressed into a high-temperature, high-pressure gas by the compressor 11, expands into a medium-temperature, low-pressure gas by the first pressure reducing device 13, dissipates heat in the first low-temperature heat exchanger 24 to become a low-temperature, low-pressure gas, and is sent back to the compressor 11 via the accumulator 19.

[0033] In the low-temperature side heat transfer circuit of the first heat transfer circuit 30, the third pump 52 is stopped, and the second pump 51 is operating. The second pump 51 sends the heat transfer medium to the first low-temperature side heat exchanger 24. The heat transfer medium, heated by absorbing heat in the first low-temperature side heat exchanger 24, is sent to the outdoor heat exchanger 42 via the third three-way valve 53, the six-way valve 44, the second three-way valve 33, and the third junction 322. At this time, the shutter of the outdoor heat exchanger 42 is closed and the fan that blows air to the outdoor heat exchanger 42 is stopped. The heated heat transfer medium passes over the frosted outdoor heat exchanger 42, defrosting it. The heat transfer medium that has passed through the outdoor heat exchanger 42 passes through the six-way valve 44 and the sixth junction 523, passes through the motor temperature control unit 81, and returns to the second pump 51.

[0034] The vehicle's thermal management system 1 generally supplies heat to the outdoor heat exchanger 42 by transferring heat from the refrigerant heated by the compressor 11 to a heat transfer medium in the first low-temperature heat exchanger 24. However, because there are limitations on the discharge pressure and discharge temperature of the compressor 11, there are limitations on the amount of heat that can be supplied to the first low-temperature heat exchanger 24, and it is not possible to make the heat transfer medium relatively hot in the first low-temperature heat exchanger 24. Therefore, the efficiency of the defrosting operation is not very good.

[0035] Furthermore, once the outdoor heat exchanger 42 has been sufficiently defrosted, as described later, the outdoor heat exchanger 42 will be used to absorb heat from the outside air, and the outside air will be used as the low-temperature heat source to realize the heat pump cycle of the refrigerant circuit 10, enabling efficient heating of the vehicle interior.

[0036] (2) Hot gas cycle heating operation diagram 3 is a schematic diagram for explaining heating operation when the heat transfer medium heating electric heater 83 cannot be used in a low-temperature environment. This type of operation is performed when the outside air temperature is extremely low and heating using the outside air as a heat source cannot be performed.

[0037] In this state, in the high-temperature side heat transfer circuit of the first heat transfer circuit 30, the first pump 31 is stopped, and no heat exchange takes place in the high-temperature side heat exchanger 22. Also, in the low-temperature side heat transfer circuit of the first heat transfer circuit 30, the second pump 51 and the third pump 52 are stopped, and no heat exchange takes place in the first low-temperature side heat exchanger 24. On the other hand, in the second heat transfer circuit 60, the fourth pump 61 is operating, and heat exchange takes place in the second low-temperature side heat exchanger 27.

[0038] In this operation, the refrigerant circuit 10 operates in a mode called a hot gas cycle or triangular cycle, in which heat is not dissipated in the condenser 12 of the high-temperature heat exchanger 22, but is dissipated in the second evaporator 17 of the second low-temperature heat exchanger 27. In the refrigerant circuit 10, the expansion valve of the first pressure reducing device 13 is fully closed, and the refrigerant does not pass through the first evaporator 14. On the other hand, the expansion valve of the second pressure reducing device 16 is open, and the refrigerant passes through the second evaporator 17. The rotational speed of the compressor 11 is adjusted based on the temperature of the heat transfer medium at the outlet of the second low-temperature heat exchanger 27. As a result, in the refrigerant circuit 10, the refrigerant is compressed into a high-temperature, high-pressure gas by the compressor 11, expands into a medium-temperature, low-pressure gas by the second pressure reducing device 16, dissipates heat in the second low-temperature heat exchanger 27 to become a low-temperature, low-pressure gas, and is sent back to the compressor 11 via the accumulator 19.

[0039] In the second heat transfer medium circuit 60, the fourth pump 61 is in operation. The fourth pump 61 sends the heat transfer medium to the second low-temperature heat exchanger 27. The heat transfer medium, heated by heat absorption in the second low-temperature heat exchanger 27, is sent to the cooler core 72. In the HVAC unit 70, air is supplied to the cooler core 72 by the blower 76. Heat exchange takes place in the cooler core 72 through which the heated heat transfer medium flows, heating the air, and the heated air is sent into the vehicle interior. Heating is performed in this manner. The heat transfer medium that has passed through the cooler core 72 returns to the fourth pump 61.

[0040] The vehicle thermal management system 1 generally supplies heat to the cooler core 72 by transferring heat from the refrigerant heated by the compressor 11 to a heat transfer medium in the second low-temperature heat exchanger 27, thereby providing heating. However, because there are limitations on the discharge pressure and discharge temperature of the compressor 11, there are limitations on the amount of heat that can be supplied to the second low-temperature heat exchanger 27, and it is not possible to raise the temperature of the heat transfer medium in the second low-temperature heat exchanger 27. Therefore, the heating efficiency is not very good.

[0041] (3) Hot gas cycle heating and defrosting operation Diagram 4 is a schematic diagram for explaining the operation of simultaneously performing heating and defrosting when the heat transfer medium heating electric heater 83 cannot be used in a low-temperature environment. Such operation is performed when heating can be performed by taking in outside air using the outdoor heat exchanger 42 once defrosting of the outdoor heat exchanger 42 is complete, and when it is required to start heating immediately.

[0042] In this state, the first pump 31 is stopped in the high-temperature side heat transfer circuit of the first heat transfer circuit 30, and no heat exchange takes place in the high-temperature side heat exchanger 22. In the low-temperature side heat transfer circuit of the first heat transfer circuit 30, the second pump 51 is operating, and heat exchange takes place in the first low-temperature side heat exchanger 24. In addition, the fourth pump 61 is operating in the second heat transfer circuit 60, and heat exchange takes place in the second low-temperature side heat exchanger 27.

[0043] At this time, in the refrigerant circuit 10, heat dissipation is not performed in the condenser 12 of the high-temperature side heat exchanger 22, and heat dissipation is performed in the first evaporator 14 of the first low-temperature side heat exchanger 24 and the second evaporator 17 of the second low-temperature side heat exchanger 27. An operation mode called a hot gas cycle or a delta cycle is implemented. In the refrigerant circuit 10, the expansion valve of the second decompression device 16 is opened, and the opening degree of the expansion valve of the first decompression device 13 is adjusted according to the temperature of the heat medium at the outlet of the first low-temperature side heat exchanger 24. The refrigerant passes through the first evaporator 14 and the second evaporator 17. Based on the temperature of the heat medium at the outlet of the second low-temperature side heat exchanger 27 and the like, the rotational speed of the compressor 11 is adjusted. As a result, in the refrigerant circuit 10, the refrigerant is compressed into a high-temperature and high-pressure gas by the compressor 11, expands through the first decompression device 13 and the second decompression device 16 to become a medium-temperature and low-pressure gas, dissipates heat in the first low-temperature side heat exchanger 24 and the second low-temperature side heat exchanger 27 to become a low-temperature and low-pressure gas, and is sent back to the compressor 11 via the accumulator 19.

[0044] In the low-temperature side heat medium circuit of the first heat medium circuit 30, the third pump 52 is stopped and the second pump 51 is operating. The second pump 51 sends the heat medium to the first low-temperature side heat exchanger 24. The heat medium heated by absorbing heat in the first low-temperature side heat exchanger 24 is sent to the outdoor heat exchanger 42 via the third three-way valve 53, the six-way valve 44, the second three-way valve 33, and the third confluence part 322. At this time, the shutter of the outdoor heat exchanger 42 is closed and the blower fan that blows air to the outdoor heat exchanger 42 is stopped. The outdoor heat exchanger 42 is defrosted by passing the heat medium heated by the frosted outdoor heat exchanger 42. The heat medium that has passed through the outdoor heat exchanger 42 passes through the motor temperature control part 81 via the six-way valve 44 and the sixth confluence part 523 and returns to the second pump 51.

[0045] In the second heat medium circuit 60, the fourth pump 61 is operating. The fourth pump 61 sends the heat medium to the second low-temperature side heat exchanger 27. The heat medium heated by absorbing heat in the second low-temperature side heat exchanger 27 is sent to the cooler core 72. In the HVAC unit 70, air is sent to the cooler core 72 by a blower 76. Heat exchange is performed in the cooler core 72 through which the heated heat medium flows, and the air is heated. The heated air is sent into the vehicle interior. Heating is thus carried out. The heat medium that has passed through the cooler core 72 returns to the fourth pump 61.

[0046] The vehicle heat management system 1 generally supplies heat to the outdoor heat exchanger 42 and the cooler core 72 by transferring the heat of the refrigerant heated by the compressor 11 to the heat medium in the first low-temperature side heat exchanger 24 and the second low-temperature side heat exchanger 27. However, since there are limitations on the discharge pressure and discharge temperature of the compressor 11, there are limitations on the heat that can be supplied to the first low-temperature side heat exchanger 24 and the second low-temperature side heat exchanger 27, and it is not possible to make the heat medium relatively high temperature in the first low-temperature side heat exchanger 24 and the second low-temperature side heat exchanger 27. Therefore, the efficiency of the defrost operation and the heating operation is not very good.

[0047] In addition, when the defrosting of the outdoor heat exchanger 42 is sufficiently performed, as will be described later, heat is absorbed from the outside air using the outdoor heat exchanger 42, and the heat pump cycle of the refrigerant circuit 10 is realized using the outside air as a heat source on the low-temperature side, enabling heating of the vehicle interior.

[0048] (4) Heating operation by outside air and motor exhaust heat Fig. 5 is a schematic diagram for explaining the heating operation when the heat medium heating electric heater 83 cannot be used in a low-temperature environment. Such an operation is performed, for example, when the defrosting of the outdoor heat exchanger 42 is sufficiently performed by the defrost operation using the above-mentioned hot gas cycle, and heating can be performed using the outside air as a heat source and the exhaust heat of the motor as a heat source.

[0049] In this state, the first pump 31 operates in the high-temperature side heat transfer circuit of the first heat transfer circuit 30, and heat exchange takes place in the high-temperature side heat exchanger 22. The fourth pump 61 is stopped, the heat transfer fluid in the second heat transfer circuit 60 does not circulate, and no heat exchange takes place in the second low-temperature side heat exchanger 27. In the low-temperature side heat transfer circuit of the first heat transfer circuit 30, the second pump 51 operates, and heat exchange takes place in the first low-temperature side heat exchanger 24.

[0050] In the refrigerant circuit 10, the expansion valve of the second pressure reducing device 16 is fully closed, and the refrigerant does not pass through the second evaporator 17. On the other hand, the opening degree of the expansion valve of the first pressure reducing device 13 is adjusted based on the outlet subcool of the condenser 12, and the refrigerant passes through the first evaporator 14. The rotational speed of the compressor 11 is adjusted based on the temperature of the heat transfer medium at the outlet of the high-temperature side heat exchanger 22, the temperature of the heat transfer medium at the outlet of the heater core 71, etc.

[0051] In the refrigerant circuit 10, the refrigerant is compressed into a high-temperature, high-pressure gas by the compressor 11, condenses and releases heat in the condenser 12 of the high-temperature side heat exchanger 22 to become a high-temperature, high-pressure liquid, expands in the first depressurization device 13 to become a low-pressure gas-liquid two-phase state, evaporates and absorbs heat in the first low-temperature side heat exchanger 24 to become a low-temperature, low-pressure gas, and is sent back to the compressor 11 via the accumulator 19.

[0052] At this time, in the high-temperature side heat transfer circuit of the first heat transfer circuit 30, the first pump 31 operates to send the heat transfer medium to the high-temperature side heat exchanger 22. The heat transfer medium heated in the high-temperature side heat exchanger 22 is sent to the heater core 71 via the first three-way valve 32. In the HVAC unit 70, air is supplied to the heater core 71 by the blower 76. Heat exchange takes place in the heater core 71 through which the high-temperature heat transfer medium flows, heating the air, and the warmed air is sent into the vehicle interior. Heating is performed in this manner. The heat transfer medium that has passed through the heater core 71 returns to the first pump 31 via the second junction 321.

[0053] Furthermore, in the low-temperature side heat transfer circuit of the first heat transfer circuit 30, the third pump 52 is stopped, and the second pump 51 is operating. The second pump 51 sends the heat transfer medium to the first low-temperature side heat exchanger 24. The heat transfer medium dissipates heat in the first low-temperature side heat exchanger 24, transferring heat to the refrigerant in the refrigerant circuit 10. The low-temperature heat transfer medium that has dissipated heat in the first low-temperature side heat exchanger 24 is sent to the outdoor heat exchanger 42 via the third three-way valve 53, the six-way valve 44, the second three-way valve 33, and the third junction 322. At this time, the shutter of the outdoor heat exchanger 42 is open and a fan that blows air to the outdoor heat exchanger 42 is operating. The heat transfer medium is heated by the outside air in the outdoor heat exchanger 42. The heated heat transfer medium is sent to the motor temperature control unit 81 via the six-way valve 44 and the sixth junction 523. The heat transfer medium is further heated by the exhaust heat from the motor in the motor temperature control unit 81 and then returned to the second pump 51.

[0054] The vehicle thermal management system 1 generally uses the heat absorbed from the outside air by the outdoor heat exchanger 42 and the exhaust heat from the motor absorbed by the motor temperature control unit 81 as low-temperature heat sources to operate the heat pump cycle of the refrigerant circuit 10 and supply heat to the heater core 71. The vehicle thermal management system 1 can efficiently heat the vehicle interior using the heat from this heater core 71.

[0055] [Operational control when the heat transfer medium heating electric heater is unavailable] An example of operational control when the heat transfer medium heating electric heater 83 is unavailable due to a malfunction or other reason will be described. Figure 6 is a flowchart illustrating an example of the operation of the control device 90 when the heat transfer medium heating electric heater 83 is unavailable. This control is executed, for example, when a malfunction of the heat transfer medium heating electric heater 83 is detected, or when it is determined that the heat transfer medium heating electric heater 83 is unavailable.

[0056] In step S1, the control device 90 determines whether or not there is a heating request. For example, a heating request is determined if the vehicle interior temperature is below a predetermined value or if the user has given a heating instruction. If it is determined that there is no heating request, the process proceeds to step S6. On the other hand, if it is determined that there is a heating request, the process proceeds to step S2.

[0057] In step S2, the control device 90 determines the operating mode. An example of determining the operating mode is shown in Figure 7. In this example, based on whether or not frost has formed on the outdoor heat exchanger 42, whether or not outside air heat absorption is possible using the outdoor heat exchanger 42, and the degree of heating requirement, it is determined which of the above-mentioned (1) defrosting operation by hot gas cycle, (2) heating operation by hot gas cycle, (3) heating and defrosting operation by hot gas cycle, or (4) heating operation by outside air and motor exhaust heat will be performed.

[0058] Whether or not ambient air heat absorption is possible is determined, for example, based on the ambient temperature. If the ambient temperature is higher than a predetermined value, ambient air heat absorption is determined to be possible; if the ambient temperature is below the predetermined value, ambient air heat absorption is determined to be impossible. For example, if the ambient temperature is higher than -15°C, ambient air heat absorption is determined to be possible; if the ambient temperature is -15°C or lower, ambient air heat absorption is determined to be impossible.

[0059] The heating requirement is determined, for example, to be high if immediate heating is needed, and low if the start of heating can be delayed. The heating requirement may also be based on air conditioning indicators calculated based on the outside air temperature, the temperature inside the vehicle, solar radiation, vehicle speed, etc. Air conditioning indicators may include, for example, the target discharge temperature from the HVAC unit 70.

[0060] If the control device 90 determines, for example, that there is frost on the outdoor heat exchanger 42, but the outside air temperature is higher than a predetermined condition and outside air heat absorption is possible after defrosting, and the heating requirement is low, it first selects to (1) perform a defrosting operation using the hot gas cycle. If the control device 90 determines, for example, that the outside air temperature is lower than a predetermined condition and outside air heat absorption is not possible, it selects to (2) perform a heating operation using the hot gas cycle. If the control device 90 determines, for example, that there is frost on the outdoor heat exchanger 42, but the outside air temperature is higher than a predetermined condition and outside air heat absorption is possible after defrosting, and the heating requirement is also high, it selects to (3) perform a heating and defrosting operation using the hot gas cycle. If the control device 90 determines, for example, that there is no frost on the outdoor heat exchanger 42 and the outside air temperature is higher than a predetermined condition and outside air heat absorption is possible, it selects to (4) perform a heating operation using outside air and motor exhaust heat.

[0061] Returning to Figure 6, let's continue the explanation. In step S3, the control device 90 controls the operation of the vehicle thermal management system 1 based on the operation mode selected in step S2, causing the vehicle thermal management system 1 to perform the operation.

[0062] In step S4, the control device 90 determines whether the currently running operation mode can be continued. For example, if frost forms on the outdoor heat exchanger 42, defrosting is completed, or the outside air temperature changes, the currently running operation of the vehicle thermal management system 1 may not be able to continue. If it is determined that the currently running operation mode cannot be continued, the process returns to step S2, and the mode determination is performed again. On the other hand, if it is determined that the currently running operation mode can be continued, the process proceeds to step S5.

[0063] In step S5, the control device 90 determines whether there is a continued heating request. If there is a continued heating request, the process returns to step S3 and the currently selected operating mode continues to be performed. If it is determined that there is no heating request, the process proceeds to step S6.

[0064] In step S6, the control device 90 operates the vehicle thermal management system 1 in an operating mode other than the heating operating mode described above, but in the requested operating mode. After that, the process returns to step S1.

[0065] According to the vehicle thermal management system 1 described above, even if a malfunction occurs in the heat transfer medium heating electric heater 83 in a low-temperature environment, the vehicle thermal management system 1 can perform heating when a heating request is made. Heating can be performed even when frost has formed on the outdoor heat exchanger 42 and outside air intake heating is not possible. Appropriate operation can be performed by determining the operating mode, such as performing only heating inside the vehicle, performing both heating and defrosting of the outdoor heat exchanger 42, or performing only defrosting of the outdoor heat exchanger 42, depending on the outside air temperature, the degree of heating request, etc.

[0066] [Modifications] Modifications of the above-described embodiment will now be explained. Here, the differences from the above-described embodiment will be explained, and the same parts will be denoted by the same reference numerals and their descriptions will be omitted. The heat transfer fluid circuit shown as an embodiment above is just an example and can be modified as appropriate. Several modifications of the heat transfer fluid circuit are shown below.

[0067] [First Modified Example] Figure 8 is a schematic diagram showing an example of the configuration of a vehicle thermal management system 2 according to the first modified example. In the above-described embodiment, the second heat transfer medium circuit 60, which includes the cooler core 72, is independent in the heat transfer medium circuit, whereas in this modified example, it is not independent. An eight-way valve 244 is provided in place of the six-way valve 44. In addition, a first four-way valve 245 and a fifth three-way valve 246 are provided. These eight-way valve 244, the first four-way valve 245, the fifth three-way valve 246, etc., switch the flow paths in various ways, thereby switching the low-temperature side heat transfer medium circuit in various ways. In addition, in this modified example, the low-temperature side heat transfer medium circuit is provided with two pumps: a second pump 251 that sends the heat transfer medium to the first low-temperature side heat exchanger 24, and a third pump 261 that sends the heat transfer medium to the second low-temperature side heat exchanger 27. In the high-temperature side heat transfer medium circuit, a second four-way valve 233 is provided in place of the second three-way valve 33. With the circuit configuration shown in Figure 8, each operating mode operates as follows:

[0068] (1) Defrosting operation by hot gas cycle In the defrosting operation by hot gas cycle, as in the embodiment described above, the first pump 31 stops, the heat transfer medium does not flow through the high-temperature side heat exchanger 22, and no heat exchange between the refrigerant and the heat transfer medium takes place in the high-temperature side heat exchanger 22. In the refrigerant circuit 10, a hot gas cycle is formed in which the refrigerant is compressed, expanded, and released heat in the compressor 11, the second pressure reducing device 16, and the second low-temperature side heat exchanger 27, respectively.

[0069] At this time, the second pump 251 stops and the third pump 261 starts operating. The heat transfer medium sent from the third pump 261 absorbs heat and is warmed in the second low-temperature side heat exchanger 27, and is sent to the outdoor heat exchanger 42 via the fifth three-way valve 246, the seventh junction 247, the first four-way valve 245, the eight-way valve 244, and the second four-way valve 233. The heated heat transfer medium passes over the frosted outdoor heat exchanger 42, defrosting it. The heat transfer medium that has passed through the outdoor heat exchanger 42 returns to the third pump 261 via the eight-way valve 244 and the first four-way valve 245.

[0070] (2) Heating operation by hot gas cycle In the heating operation by hot gas cycle, as in the embodiment described above, the first pump 31 stops, the heat transfer medium does not flow through the high-temperature side heat exchanger 22, and no heat exchange between the refrigerant and the heat transfer medium takes place in the high-temperature side heat exchanger 22. In the refrigerant circuit 10, a hot gas cycle is formed in which the refrigerant is compressed, expanded, and released heat in the compressor 11, the second pressure reducing device 16, and the second low-temperature side heat exchanger 27, respectively.

[0071] At this time, the second pump 251 stops and the third pump 261 operates. The heat transfer medium sent from the third pump 261 absorbs heat and is heated in the second low-temperature heat exchanger 27, and is sent to the cooler core 72 via the fifth three-way valve 246. In the HVAC unit 70, air is supplied to the cooler core 72 by the blower 76. Heat exchange takes place in the cooler core 72 through which the heated heat transfer medium flows, heating the air, and the heated air is sent into the vehicle interior. Heating is performed in this manner. The heat transfer medium that has passed through the cooler core 72 returns to the third pump 261 via the seventh junction 247 and the first four-way valve 245.

[0072] (3) Heating and defrosting operation by hot gas cycle In the heating and defrosting operation by hot gas cycle, as in the embodiment described above, the first pump 31 stops, the heat transfer medium does not flow through the high-temperature side heat exchanger 22, and no heat exchange between the refrigerant and the heat transfer medium takes place in the high-temperature side heat exchanger 22. In the refrigerant circuit 10, a hot gas cycle is formed in which the refrigerant is compressed, expanded, and released heat in the compressor 11, the first pressure reducing device 13, and the first low-temperature side heat exchanger 24, respectively, and a hot gas cycle is formed in which the refrigerant is compressed, expanded, and released heat in the compressor 11, the second pressure reducing device 16, and the second low-temperature side heat exchanger 27, respectively.

[0073] At this time, the third pump 261 and the second pump 251 operate. The heat transfer medium sent from the third pump 261 absorbs heat and is heated in the second low-temperature heat exchanger 27, and is sent to the cooler core 72 via the fifth three-way valve 246. In the HVAC unit 70, air is supplied to the cooler core 72 by the blower 76. Heat exchange takes place in the cooler core 72 through which the heated heat transfer medium flows, heating the air, and the heated air is sent into the vehicle interior. Heating is performed in this manner. The heat transfer medium that has passed through the cooler core 72 passes through the motor temperature control unit 81 via the seventh junction 247, the first four-way valve 245, and the eight-way valve 244, and returns to the second pump 51 via the eight-way valve 244 and the first four-way valve 245.

[0074] Furthermore, the heat transfer medium sent from the second pump 251 is heated by heat absorption in the first low-temperature side heat exchanger 24, passes through the fourth three-way valve 54 and the battery temperature control unit 82, and is sent to the outdoor heat exchanger 42 via the fifth junction unit 522, the eight-way valve 244 and the second four-way valve 233. The heated heat transfer medium passes over the frosted outdoor heat exchanger 42, defrosting it. The heat transfer medium that has passed through the outdoor heat exchanger 42 returns to the second pump 251 via the eight-way valve 244.

[0075] (4) Heating operation using outside air and motor waste heat In heating operation using outside air and motor waste heat, the first pump 31 operates in the high-temperature heat transfer medium circuit, and heat exchange takes place in the high-temperature heat exchanger 22. In the refrigerant circuit 10, a heat pump cycle is formed in which the refrigerant is compressed, released, expanded, and absorbed in the compressor 11, the high-temperature heat exchanger 22, the second pressure reducing device 16, and the second low-temperature heat exchanger 27, respectively.

[0076] At this time, the heat transfer medium sent from the first pump 31 is heated by heat absorption in the high-temperature heat exchanger 22 and sent to the heater core 71 via the first three-way valve 32. In the HVAC unit 70, air is supplied to the heater core 71 by the blower 76. Heat exchange takes place in the heater core 71 through which the heated heat transfer medium flows, heating the air, and the heated air is sent into the vehicle interior. Heating is performed in this manner. The heat transfer medium that has passed through the heater core 71 returns to the first pump 31 via the second junction 321.

[0077] At this time, in the low-temperature heat transfer medium circuit, the second pump 251 stops and the third pump 261 operates. The heat transfer medium sent from the third pump 261 dissipates heat in the second low-temperature heat exchanger 27, supplying heat to the refrigerant in the refrigerant circuit 10. The low-temperature heat transfer medium that has dissipated heat in the second low-temperature heat exchanger 27 is sent to the outdoor heat exchanger 42 via the fifth three-way valve 246, the seventh junction 247, the first four-way valve 245, the eight-way valve 244, and the second four-way valve 233. The heat transfer medium is heated in the outdoor heat exchanger 42. The heated heat transfer medium is sent to the motor temperature control unit 81 via the eight-way valve 244. The heat transfer medium is further heated in the motor temperature control unit 81. The heated heat transfer medium returns to the third pump 261 via the eight-way valve 244 and the first four-way valve 245.

[0078] [Second Modification] Figure 9 is a schematic diagram showing an example of the configuration of a vehicle thermal management system 3 according to the second modification. This modification is similar in configuration to the vehicle thermal management system 2 according to the first modification described with reference to Figure 8, and the second four-way valve 233 portion of the first modification is configured by a combination of a second three-way valve 33 and a third junction 322, similar to the vehicle thermal management system 1 of the above-described embodiment.

[0079] In the first modified vehicle thermal management system 2, the flow path through which the heat transfer medium flows from the eight-way valve 244 to the outdoor heat exchanger 42 via the second four-way valve 233 is the same as in the second modified vehicle thermal management system 3, where the heat transfer medium flows from the eight-way valve 244 to the outdoor heat exchanger 42 via the second three-way valve 33 and the third confluence section 322. The other parts are the same as in the first modified vehicle thermal management system 2.

[0080] [Third Modification] Figure 10 is a schematic diagram showing an example of the configuration of a vehicle thermal management system 4 according to the third modification. In the third modification, compared to the embodiment described above, the arrangement of the second pump 451 and the third pump 452 in the low-temperature side heat transfer fluid circuit of the first heat transfer fluid circuit 30 is different. Also, an eight-way valve 444 is provided instead of the six-way valve 44. In addition, a sixth three-way valve 445 is provided. These eight-way valve 444, the sixth three-way valve 445, etc., switch the flow path in various ways, thereby switching the low-temperature side heat transfer fluid circuit in various ways. With the circuit configuration shown in Figure 10, the system operates as follows in each operating mode.

[0081] (1) Defrosting operation by hot gas cycle In the defrosting operation by hot gas cycle, as in the embodiment described above, the first pump 31 stops, the heat transfer medium does not flow through the high-temperature side heat exchanger 22, and no heat exchange between the refrigerant and the heat transfer medium takes place in the high-temperature side heat exchanger 22. In the refrigerant circuit 10, a hot gas cycle is formed in which the refrigerant is compressed, expanded, and released heat in the compressor 11, the first pressure reducing device 13, and the first low-temperature side heat exchanger 24, respectively.

[0082] At this time, the fourth pump 61 and the third pump 452 stop, and the second pump 451 operates. The heat transfer medium sent from the second pump 451 absorbs heat and is warmed in the first low-temperature side heat exchanger 24, and is sent to the outdoor heat exchanger 42 via the sixth three-way valve 445, the eight-way valve 444, the second three-way valve 33, and the third junction 322. The heated heat transfer medium passes over the frosted outdoor heat exchanger 42, defrosting it. The heat transfer medium that has passed through the outdoor heat exchanger 42 returns to the second pump 451 via the eight-way valve 444 and the third branch 447.

[0083] (2) Heating operation by hot gas cycle In the heating operation by hot gas cycle, as in the embodiment described above, the first pump 31 stops, the heat transfer medium does not flow through the high-temperature side heat exchanger 22, and no heat exchange between the refrigerant and the heat transfer medium takes place in the high-temperature side heat exchanger 22. In the refrigerant circuit 10, a hot gas cycle is formed in which the refrigerant is compressed, expanded, and released heat in the compressor 11, the second pressure reducing device 16, and the second low-temperature side heat exchanger 27, respectively.

[0084] At this time, the second pump 451 and the third pump 452 stop, and the fourth pump 61 operates. The heat transfer medium sent from the fourth pump 61 absorbs heat and is heated in the second low-temperature heat exchanger 27, and then sent to the cooler core 72. In the HVAC unit 70, air is supplied to the cooler core 72 by the blower 76. Heat exchange takes place in the cooler core 72 through which the heated heat transfer medium flows, heating the air, and the heated air is sent into the vehicle interior. Heating is performed in this manner. The heat transfer medium that has passed through the cooler core 72 returns to the fourth pump 61.

[0085] (3) Heating and defrosting operation by hot gas cycle In the heating and defrosting operation by hot gas cycle, as in the embodiment described above, the first pump 31 stops, the heat transfer medium does not flow through the high-temperature side heat exchanger 22, and no heat exchange between the refrigerant and the heat transfer medium takes place in the high-temperature side heat exchanger 22. In the refrigerant circuit 10, a hot gas cycle is formed in which the refrigerant is compressed, expanded, and released heat in the compressor 11, the first pressure reducing device 13, and the first low-temperature side heat exchanger 24, respectively, and a hot gas cycle is formed in which the refrigerant is compressed, expanded, and released heat in the compressor 11, the second pressure reducing device 16, and the second low-temperature side heat exchanger 27, respectively.

[0086] At this time, the third pump 452 stops, and the fourth pump 61 and the second pump 451 operate. The heat transfer medium sent from the fourth pump 61 absorbs heat and is heated in the second low-temperature heat exchanger 27, and then sent to the cooler core 72. In the HVAC unit 70, air is supplied to the cooler core 72 by the blower 76. Heat exchange takes place in the cooler core 72 through which the heated heat transfer medium flows, heating the air, and the heated air is sent into the vehicle interior. Heating is performed in this manner. The heat transfer medium that has passed through the cooler core 72 returns to the fourth pump 61.

[0087] Furthermore, the heat transfer medium sent from the second pump 451 is heated by heat absorption in the first low-temperature side heat exchanger 24 and sent to the outdoor heat exchanger 42 via the sixth three-way valve 445, the eight-way valve 444, the second three-way valve 33, and the third junction 322. The heated heat transfer medium passes over the frosted outdoor heat exchanger 42, defrosting it. After passing through the outdoor heat exchanger 42, the heat transfer medium returns to the second pump 451 via the eight-way valve 444 and the third branching section 447.

[0088] (4) Heating operation using outside air and motor waste heat In the heating operation using outside air and motor waste heat, the first pump 31 operates in the high-temperature heat transfer medium circuit, and heat exchange takes place in the high-temperature heat exchanger 22. In the refrigerant circuit 10, a heat pump cycle is formed in which the refrigerant is compressed, released, expanded, and absorbed in the compressor 11, the high-temperature heat exchanger 22, the first pressure reducing device 13, and the first low-temperature heat exchanger 24, respectively.

[0089] At this time, the heat transfer medium sent from the first pump 31 is heated by heat absorption in the high-temperature heat exchanger 22 and sent to the heater core 71 via the first three-way valve 32. In the HVAC unit 70, air is supplied to the heater core 71 by the blower 76. Heat exchange takes place in the heater core 71 through which the heated heat transfer medium flows, heating the air, and the heated air is sent into the vehicle interior. Heating is performed in this manner. The heat transfer medium that has passed through the heater core 71 returns to the first pump 31 via the second junction 321.

[0090] At this time, in the low-temperature side heat transfer medium circuit, the fourth pump 61 and the third pump 452 stop, and the second pump 451 operates. The heat transfer medium sent from the second pump 451 dissipates heat in the first low-temperature side heat exchanger 24, supplying heat to the refrigerant in the refrigerant circuit 10. The low-temperature heat transfer medium that has dissipated heat in the first low-temperature side heat exchanger 24 is sent to the outdoor heat exchanger 42 via the sixth three-way valve 445, the eight-way valve 444, the second three-way valve 33, and the third junction 322. The heat transfer medium is heated in the outdoor heat exchanger 42. The heated heat transfer medium is sent to the motor temperature control unit 81 via the eight-way valve 244. The heat transfer medium is further heated in the motor temperature control unit 81. The heated heat transfer medium returns to the second pump 451 via the eight-way valve 444 and the third branching unit 447.

[0091] [Fourth Modification] Figure 11 is a schematic diagram showing an example of the configuration of a vehicle thermal management system 5 according to the fourth modification. In the fourth modification, the arrangement of the second pump 551 in the low-temperature side heat transfer fluid circuit of the first heat transfer fluid circuit 30 is different from that of the embodiment described above. In this modification, the low-temperature side heat transfer fluid circuit is switched in various ways by the switching of the flow path by the six-way valve 544, the third three-way valve 53, the third four-way valve 546, etc. For each operating mode of this modification with the circuit configuration shown in Figure 11, only the parts that differ from the third modification will be explained. In the operation according to the fourth modification, only the flow path of the low-temperature side heat transfer fluid circuit of the first heat transfer fluid circuit 30 differs from the operation according to the third modification. Everything else is the same as in the third modification.

[0092] In the fourth modified example, during the defrosting operation using the hot gas cycle, and during the heating and defrosting operation using the hot gas cycle, the heat transfer medium sent from the second pump 551 is heated by heat absorption in the first low-temperature side heat exchanger 24 and sent to the outdoor heat exchanger 42 via the third three-way valve 53, the six-way valve 544, the third four-way valve 546, the second three-way valve 33, and the third junction 322. The heated heat transfer medium passes over the frosted outdoor heat exchanger 42, defrosting the outdoor heat exchanger 42. The heat transfer medium that has passed through the outdoor heat exchanger 42 returns to the second pump 551 via the six-way valve 544 and the eighth junction 547.

[0093] In the fourth modified example, during heating operation using outside air and motor exhaust heat, the heat transfer medium sent from the second pump 551 dissipates heat in the first low-temperature side heat exchanger 24, transferring heat to the refrigerant in the refrigerant circuit 10. The low-temperature heat transfer medium that has dissipated heat in the first low-temperature side heat exchanger 24 is branched by the third three-way valve 53, and in one flow, it is sent to the motor temperature control unit 81 via the six-way valve 544. The heat transfer medium is heated in the motor temperature control unit 81. The heated heat transfer medium returns to the second pump 451 via the eighth junction 547. In the other flow branched by the third three-way valve 53, the heat transfer medium is sent to the outdoor heat exchanger 42 via the fourth junction 521, the third four-way valve 546, the second three-way valve 33, and the third junction 322. The heat transfer medium is heated in the outdoor heat exchanger 42. The heated heat transfer medium passes through the battery temperature control unit 82 via the hexagonal valve 544, the third quadrant valve 546, and the fourth quadrant valve 54, and returns to the second pump 551 via the fifth junction 522, the second branch 511, the hexagonal valve 544, and the eighth junction 547.

[0094] [Fifth Modification] Figure 12 is a schematic diagram showing an example of the configuration of a vehicle thermal management system 6 according to the fifth modification. In the fifth modification, compared to the embodiment described above, a fourth four-way valve 645 and a fifth four-way valve 646 are provided instead of the six-way valve 44. In this modification, the low-temperature side heat transfer fluid circuit is switched in various ways by the fourth four-way valve 645, the fifth four-way valve 646, etc. switching the flow path in various ways. For each operating mode of this modification with the circuit configuration shown in Figure 12, only the parts that differ from the third modification will be explained. In the operation according to the fifth modification, only the flow path of the low-temperature side heat transfer fluid circuit of the first heat transfer fluid circuit 30 differs from the operation according to the third modification. Everything else is the same as in the third modification.

[0095] In the fifth modified example, during the defrosting operation using the hot gas cycle, and during the heating and defrosting operation using the hot gas cycle, the heat transfer medium sent from the second pump 51 is heated by heat absorption in the first low-temperature side heat exchanger 24 and sent to the outdoor heat exchanger 42 via the third three-way valve 53, the fourth four-way valve 645, the fifth four-way valve 646, the second three-way valve 33, and the third junction 322. The heated heat transfer medium passes over the frosted outdoor heat exchanger 42, defrosting the outdoor heat exchanger 42. After passing through the outdoor heat exchanger 42, the heat transfer medium passes through the fourth four-way valve 645 and the sixth junction 523, goes through the motor temperature control unit 81, and returns to the second pump 551.

[0096] In the fifth modified example, during heating operation using outside air and motor exhaust heat, the heat transfer medium sent from the second pump 51 dissipates heat in the first low-temperature side heat exchanger 24, transferring heat to the refrigerant in the refrigerant circuit 10. The low-temperature heat transfer medium that dissipates heat in the first low-temperature side heat exchanger 24 is sent to the outdoor heat exchanger 42 via the third three-way valve 53, the fourth four-way valve 645, the fifth four-way valve 646, the second three-way valve 33, and the third junction 322. The heat transfer medium is heated in the outdoor heat exchanger 42. The heated heat transfer medium is sent to the motor temperature control unit 81 via the fourth four-way valve 645 and the sixth junction 523. The heat transfer medium is further heated in the motor temperature control unit 81 and returned to the second pump 451.

[0097] In each of the above-described modifications, the device operates in the same manner as the embodiments described above, and the same effects are obtained.

[0098] Although the present invention has been described above with reference to preferred embodiments, it goes without saying that the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the present invention.

[0099] 1: Vehicle thermal management system 10: Refrigerant circuit, 11: Compressor, 12: Condenser, 13: First pressure reducing device, 14: First evaporator, 15: First check valve, 16: Second pressure reducing device, 17: Second evaporator, 18: Second check valve, 19: Accumulator, 111: First branch section, 121: First junction section 22: High-temperature side heat exchanger, 24: First low-temperature side heat exchanger, 27: Second low-temperature side heat exchanger 30: First heat transfer medium circuit, 31: First pump, 32: First three-way valve, 33: Second three-way valve, 34: First tank, 321: Second junction section, 322: Third junction section 42: Outdoor heat exchanger, 44: Six-way valve 51: Second pump, 52: Third pump, 53: Third three-way valve, 54: Fourth three-way valve, 55: Third check valve, 56: Second tank, 57: Third tank, 511: Second branch section, 521: Fourth junction section, 522: Fifth junction section, 523: Sixth junction section 60: Second heat transfer fluid circuit, 61: Fourth pump, 62: Fourth tank 70: HVAC unit, 71: Heater core, 72: Cooler core, 75: Airflow passage, 76: Blower 81: Motor temperature control section, 82: Battery temperature control section, 83: Heat transfer fluid heating electric heater 90: Control device

Claims

1. A refrigerant circuit including a compressor, a condenser of a high-temperature heat exchanger, a depressurizer, and an evaporator of a low-temperature heat exchanger; a heat transfer medium circuit configured to carry a heat transfer medium that exchanges heat with the refrigerant flowing through the refrigerant circuit; and a control device configured to control the operation of the refrigerant circuit and the heat transfer medium circuit, wherein the heat transfer medium circuit comprises a heater core for heating that can be connected to the high-temperature heat exchanger, a cooler core for cooling that can be connected to the low-temperature heat exchanger, a heat transfer medium heating electric heater configured to heat the heat transfer medium flowing through the low-temperature heat exchanger, an outdoor heat exchanger configured to exchange heat between the heat transfer medium and the outside air, and a target equipment temperature control unit configured to control the temperature of the equipment to be temperature controlled using the heat transfer medium, wherein the control device, when the heat transfer medium heating electric heater cannot be used in a low-temperature environment, determines that there is frost on the outdoor heat exchanger, the outside air temperature is higher than predetermined conditions, and the heating requirement is low, selects to perform a defrosting operation using a hot gas cycle. The system is configured to select to perform heating operations using a hot gas cycle if it is determined that the outside air temperature is lower than predetermined conditions, and to select to perform heating and defrosting operations using a hot gas cycle if it is determined that there is frost on the outdoor heat exchanger, the outside air temperature is higher than predetermined conditions, and the heating requirement is also high, the defrosting operation using a hot gas cycle is an operation in which the refrigerant releases heat in the evaporator to heat the heat transfer medium flowing through the low-temperature heat exchanger without performing heat exchange in the high-temperature heat exchanger, and the heated heat transfer medium is flowed to the outdoor heat exchanger to perform defrosting, the heating operation using a hot gas cycle is an operation in which the refrigerant releases heat in the evaporator to heat the heat transfer medium flowing through the low-temperature heat exchanger without performing heat exchange in the high-temperature heat exchanger, and the heated heat transfer medium is flowed to the cooler core to perform heating, A vehicle thermal management system in which the heating and defrosting operations using the hot gas cycle are performed by the refrigerant releasing heat in the evaporator without performing heat exchange in the high-temperature side heat exchanger, heating the heat transfer medium flowing through the low-temperature side heat exchanger, flowing the heated heat transfer medium to the cooler core for heating, and flowing the heated heat transfer medium to the outdoor heat exchanger for defrosting.

2. The control device is configured to select to perform heating using outside air and waste heat from the equipment to be temperature controlled when, in a low-temperature environment, the electric heater for heating the heat medium cannot be used, and when it is determined that there is no frost on the outdoor heat exchanger and the outside air temperature is higher than a predetermined condition, wherein the heating operation using outside air and waste heat from the equipment to be temperature controlled is an operation in which, in the low-temperature side heat exchanger through which the heat medium that has absorbed heat in the outdoor heat exchanger or the equipment to be temperature controlled flows, the refrigerant absorbs heat in the evaporator and the refrigerant releases heat in the condenser to heat the heat medium flowing through the high-temperature side heat exchanger, and the heated heat medium is flowed to the heater core to perform heating, as described in claim 1.

3. The vehicle thermal management system according to claim 1 or 2, wherein the low-temperature side heat exchanger comprises a first low-temperature side heat exchanger and a second low-temperature side heat exchanger, and the heat transfer medium circuit comprises a first heat transfer medium circuit including the first low-temperature side heat exchanger, the heat transfer medium heating electric heater, the outdoor heat exchanger, and the target equipment temperature control unit, and a second heat transfer medium circuit including the second low-temperature side heat exchanger and the cooler core.

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