Heat management system for vehicle

Abstract

To surely supply a refrigerant in a liquid phase when a battery for supplying electric power to an electric motor for driving a vehicle is cooled by the refrigerant of a refrigeration cycle circuit of an air conditioner.SOLUTION: When front and rear air-conditioning units 28F, 28R are performing a dehumidifying and heating operation and a battery 18 is to be cooled, a refrigeration cycle circuit 30 performs a cooling operation to supply a refrigerant in a liquid phase to front and rear evaporators 42F, 42R and a battery-cooling heat-exchanger 41. A heating circuit 32 supplies a high-temperature liquid heated by an electric heater 38 to front and rear heater cores 44F, 44R. Air cooled by the front and rear evaporators 42F, 42R is warmed by the front and rear heater cores 44F, 44R and supplied to a passenger compartment 20. A battery cooling liquid cooled by the battery-cooling heat-exchanger 41 is sent to the battery 18 to cool the battery.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a thermal management system for air conditioning a passenger compartment of a vehicle and for managing the temperature of on-board equipment. [Background technology]

[0002] Patent Document 1 listed below shows a vehicle equipped with a front air conditioning unit (2) that sends temperature- and humidity-controlled air to the front space of the passenger compartment, and a rear air conditioning unit (3) that sends temperature- and humidity-controlled air to the rear space. The front and rear air conditioning units (2, 3) each have a heater core (27, 48) and an evaporator (26, 47), and can independently condition the air in the front and rear of the passenger compartment.

[0003] In addition, a vehicle air conditioning system is known that performs dehumidifying and heating operation in which air is cooled and dehumidified by an evaporator while being heated by a heater core in a predetermined range determined by the relationship between the outside air temperature and the temperature blown out from the air conditioning unit.

[0004] The reference numerals in the parentheses above are the reference numerals used in the following Patent Document 1, and are not related to the reference numerals used in the description of the embodiments of the present application. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-103643 Summary of the Invention [Problem to be solved by the invention]

[0006] When a refrigeration cycle circuit for an air conditioning unit cools a battery that supplies power to an electric motor that drives a vehicle, supplying refrigerant to the front and rear air conditioning units and also supplying refrigerant for battery cooling may result in insufficient air conditioning and battery cooling. In particular, when the air conditioner is operating in dehumidifying and heating mode, the refrigerant supplied to the evaporators and battery-cooling heat exchangers of the front and rear air conditioning units may be in a gas-liquid two-phase state. This may prevent adequate control of the flow rate of the refrigerant supplied to each evaporator and battery-cooling heat exchanger, potentially preventing the desired air conditioning and battery cooling performance.

[0007] The present invention provides a vehicle thermal management system that can achieve required air conditioning performance and battery cooling performance in the dehumidifying operating range. [Means for solving the problem]

[0008] The vehicle thermal management system of the present invention includes a front air conditioning unit that conditions the air in a space in front of the vehicle passenger compartment, a rear air conditioning unit that conditions the air in a space in rear of the passenger compartment, a battery cooling circuit that circulates a coolant that cools a battery that supplies power to an electric motor that drives the vehicle, a refrigeration cycle circuit that supplies refrigerant to the front air conditioning unit and the rear air conditioning unit and also supplies refrigerant to a battery cooling heat exchanger that exchanges heat between the coolant in the battery cooling circuit and the refrigerant, and a heating circuit that generates a high-temperature liquid using a heat source or the refrigerant in the refrigeration cycle circuit and supplies the high-temperature liquid to the front air conditioning unit and the rear air conditioning unit. A dehumidifying and heating operating range is defined by a required outlet temperature that is a control target for the temperature of air discharged from the front air conditioning unit and the rear air conditioning unit and by an outside air temperature. In the dehumidifying and heating operation range, when the front and rear air conditioning units are operating and the battery cooling demand is equal to or greater than the first demand value, the refrigeration cycle circuit performs cooling operation and supplies refrigerant to the front and rear air conditioning units and the battery cooling heat exchanger. The heating circuit generates high-temperature liquid using a heat source. The battery cooling circuit cools the battery with coolant cooled by the refrigerant in the refrigeration cycle circuit in the battery cooling heat exchanger.

[0009] By operating the refrigeration cycle circuit in cooling mode, the refrigerant is in a liquid phase only, which allows the refrigerant to be sent to the front air conditioning unit, the rear air conditioning unit, and the battery cooling heat exchanger.

[0010] In the vehicle thermal management system described above, when the battery cooling requirement is equal to or greater than a second requirement value higher than a first requirement value and the battery charge level is lower than a predetermined value, the supply of refrigerant to the front air conditioning unit and the rear air conditioning unit by the refrigeration cycle circuit can be stopped. By reducing the power consumed by the refrigeration cycle circuit, the driving distance by the electric motor can be extended.

[0011] In the above-mentioned vehicle thermal management system, the refrigeration cycle circuit can have a compressor that compresses the refrigerant and an outdoor heat exchanger that exchanges heat with outside air, and during cooling operation, the entire amount of refrigerant compressed and discharged by the compressor passes through the outdoor heat exchanger and is liquefied.

[0012] In the above-described vehicle thermal management system, the heat source of the heating circuit may be one or both of an engine that drives the vehicle and an electric heater. [Effects of the Invention]

[0013] In the dehumidifying and heating operation range, when both the front and rear air conditioning units are operating and battery cooling is required, liquid-phase refrigerant can be sent to the front and rear air conditioning units and the battery cooling heat exchanger. Compared to sending refrigerant in a gas-liquid two-phase state, the amount of refrigerant sent to the front and rear air conditioning units and the battery cooling heat exchanger can be appropriately adjusted. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing a schematic configuration of a vehicle equipped with a thermal management system according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram showing a front air conditioning unit and its control unit. [Figure 3] 1 is a diagram illustrating a schematic configuration of a thermal management system according to an embodiment of the present invention; [Figure 4] FIG. 4 is a diagram showing conditions that define the operation modes of the air conditioning apparatus. [Figure 5] FIG. 2 is a diagram showing the operating state of the thermal management system, particularly during heating operation using engine coolant. [Figure 6] FIG. 2 is a diagram showing the operating state of the thermal management system, particularly showing the state during heating operation using an electric heater. [Figure 7] FIG. 2 is a diagram showing the operating state of the thermal management system, particularly showing the state during heating operation by heat pump operation of the refrigeration cycle circuit. [Figure 8] FIG. 2 is a diagram showing the operating state of the thermal management system, particularly the state during cooling operation. [Figure 9] FIG. 10 is a diagram showing the operating state of the thermal management system, particularly the state during parallel dehumidifying and heating operation. [Figure 10] FIG. 10 is a diagram showing the operating state of the thermal management system, particularly during serial dehumidifying and heating operation. [Figure 11] FIG. 10 is a diagram showing the operating state of the thermal management system, particularly when the front and rear air conditioning units are operating and cooling the battery in the dehumidifying and heating area. [Figure 12] FIG. 10 is a diagram showing the operating state of the thermal management system, particularly showing the state when there is a strong demand for battery cooling and the amount of stored battery power is low in the dehumidifying heating region. [Figure 13] FIG. 2 is a diagram showing a part of the control flow of the thermal management system. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the general configuration of a thermal management system 12 of a vehicle 10. The vehicle 10 is equipped with an engine 14 and two electric motors 16F, 16R that drive the front and rear wheels, respectively, as prime movers for driving the vehicle 10. The vehicle 10 is equipped with a battery 18 that supplies power to the electric motors 16F, 16R and is charged with electricity generated by the electric motors 16F, 16R during braking. The vehicle may be equipped with a single electric motor that drives only the front wheels or the rear wheels. Furthermore, the vehicle may be equipped with no engine and drive one or both of the front and rear wheels with an electric motor. Hereinafter, for simplicity, the electric motors 16F, 16R will be simply referred to as motor 16.

[0016] The thermal management system 12 cools the engine 14, the motor 16, and the battery 18, and also provides air conditioning for the passenger compartment 20. The cooling system for the engine 14 includes an engine radiator 22 that dissipates heat generated by the engine through engine coolant. The engine coolant flows through piping connecting the engine 14 and the engine radiator 22 and circulates between the engine 14 and the engine radiator 22. In FIG. 1, the piping connecting the engine 14 and the engine radiator 22 is omitted. The cooling system for the motor 16 includes a motor radiator 24 that dissipates heat generated by the motor 16 through motor coolant. The motor coolant flows through piping connecting the motor 16 and the motor radiator 24 and circulates between the motor 16 and the motor radiator 24. In FIG. 1, the piping connecting the motor 16 and the motor radiator 24 is omitted.

[0017] The thermal management system 12 includes an air conditioner 26 that conditions the passenger compartment 20. The air conditioner 26 has an air conditioning unit 28 that supplies air whose temperature, humidity, etc. have been regulated to the passenger compartment 20. The air conditioning unit 28 includes a front air conditioning unit 28F that conditions the front seat space of the passenger compartment 20 and a rear air conditioning unit 28R that conditions the rear seat space. The air conditioner 26 includes a refrigeration cycle circuit 30 that supplies refrigerant to the air conditioning unit 28 and a heating circuit 32 that supplies heated liquid. The refrigeration cycle circuit 30 includes a compressor 34 that compresses the refrigerant and an outdoor condenser 36 that cools the refrigerant compressed by the compressor 34 with outside air to liquefy it. The compressor 34 may be an electric compressor driven by an electric motor, and the output of the compressor 34 can be adjusted by controlling the rotational speed of the electric motor. The heating circuit 32 includes an electric heater 38 as a heat source. The refrigeration cycle circuit 30 and the heating circuit 32, including the other cooling systems of the thermal management system 12, will be described in more detail below.

[0018] The thermal management system 12 further includes a battery cooling circuit 40 that cools the battery 18. The battery cooling circuit 40 cools the battery 18 by supplying battery coolant that has been cooled by the refrigerant of the refrigeration cycle circuit 30 in a battery cooling heat exchanger 41 to the battery 18.

[0019] 2 is a diagram schematically illustrating the configuration of the front air conditioning unit 28F. The front air conditioning unit 28F has a front evaporator 42F, which is one of the components of the refrigeration cycle circuit 30, and a front heater core 44F, which is one of the components of the heating circuit 32, and further has an air conditioning case 46 that houses the front evaporator 42F and the front heater core 44F. The air conditioning case 46 has an air inlet 48 that introduces air into the air conditioning case 46. The air inlet 48 includes an inside air inlet 48C that introduces air from inside the passenger compartment 20 and an outside air inlet 48E that introduces air from outside the vehicle. The air conditioning case 46 also has an air outlet 50 that sends conditioned air toward a predetermined location. The air outlets 50 include a head outlet 50H that delivers airflow toward the heads and surrounding areas of front seat occupants, a foot outlet 50F that delivers airflow toward the feet of the front seat occupants, and a defroster outlet 50D that delivers airflow toward the interior surface of the windshield. The airflow delivered from the head outlet 50H passes through a duct in the instrument panel (not shown) and is blown out toward the heads and surrounding areas of the front seat occupants in the passenger compartment 20 from multiple outlets formed in the instrument panel. The airflow delivered from the foot outlet 50F is blown out toward the feet of the front seat occupants directly from the foot outlet 50F or through a duct in the instrument panel. The airflow delivered from the defroster outlet 50D passes through a duct in the instrument panel and is blown out from an outlet provided opposite the lower edge of the windshield. The front air conditioning unit 28F has a blower 52 disposed upstream of the air conditioning case 46. The blower 52 generates an air flow that flows from the air inlet 48 to the air outlet 50.

[0020] An inside / outside air switching door 54 is disposed at the confluence of the flow path from the inside air inlet 48C and the flow path from the outside air inlet 48E. The inside / outside air switching door 54 is rotatable between a position that closes the inside air inlet 48C and a position that closes the outside air inlet 48E, and the mixing ratio of the inside air and the outside air is adjusted according to the rotation angle. An air mix door 56 is disposed between the front evaporator 42F and the front heater core 44F. The air mix door 56 rotates to adjust the amount of air that passes through the front evaporator 42F and the front heater core 44F. An outlet door 58 that opens and closes the air outlet 50 is provided corresponding to each air outlet 50. Specifically, a head outlet door 58H is provided at the head outlet 50H, a foot outlet door 58F is provided at the foot outlet 50F, and a defroster outlet door 58D is provided at the defroster outlet 50D, and the amount of air blown from each outlet 50 is adjusted by the opening degree of each outlet door 58.

[0021] The volume of air blown by the blower 52, the rotation angle of the inside / outside air switching door 54 and the air mix door 56, and the opening degree of each outlet door 58 are controlled by a control unit 60. The control unit 60 controls the rotation angle of the inside / outside air switching door 54 and the air mix door 56, the opening degree of each outlet door 58, and the volume of air blown by the blower 52 based on conditions set by the occupant and environmental conditions. The occupant sets a desired temperature using a temperature setting switch 62, and further sets the air outlet 50 from which they want air to be blown using an outlet selector switch 64. Selection of the air outlet 50 can be made in a blowing mode that selects one of the air outlets 50H, 50F, and 50D individually, or in a blowing mode that blows air from both the head outlet 50H and the foot outlet 50F. The occupant can also set the automatic air conditioning mode using the automatic air conditioning switch 66. In this case, the control unit 60 selects the air outlet 50 from which to blow air according to a predetermined program in accordance with the desired temperature and environmental conditions. The control unit 60 receives inputs such as the air temperature in the passenger compartment 20 detected by a room temperature sensor 68, the outside air temperature detected by an outside air temperature sensor 70, the liquid temperature in the heating circuit 32 detected by a liquid temperature sensor 72, and the amount of solar radiation entering the passenger compartment 20 detected by a solar radiation sensor 74. The control unit 60 also receives inputs such as the temperature of the air immediately after passing through the front evaporator 42F (evaporator outlet temperature) detected by an evaporator outlet temperature sensor 76 located immediately after the front evaporator 42F.

[0022] The rear air conditioning unit 28R has a configuration similar to that of the front air conditioning unit 28F and is not shown in the drawings. The rear air conditioning unit 28R has an air conditioning case that houses the rear evaporator 42R and the rear heater core 44R (see FIG. 1), and the air conditioning case is provided with an air inlet and an air outlet. In the rear air conditioning unit 28R, the air inlet does not need to include an outside air inlet, and the air outlet does not need to include a defroster outlet. Like the front air conditioning unit 28F, the rear air conditioning unit 28R can send conditioned air to either the heads or the areas around them and / or the feet of rear seat occupants.

[0023] The rear air conditioning unit 28R can be switched on and off by the passenger. When the passenger operates the rear air conditioning switch 67, the control unit 60 operates the rear air conditioning unit 28R in addition to the front air conditioning unit 28F. The temperature setting and air outlet mode can be selected independently for the front air conditioning unit 28F and the rear air conditioning unit 28R.

[0024] The control unit 60 is a processing device that controls the air conditioning device 26 in accordance with a predetermined program, and operates to achieve the temperature and air blowing mode desired by the occupant in accordance with the above-mentioned temperatures, the amount of solar radiation, and the like.

[0025] FIG. 3 is a schematic diagram illustrating the configuration of the thermal management system 12. Components already described are designated by the same reference numerals. The refrigeration cycle circuit 30 includes the compressor 34, the outdoor condenser 36, the front and rear evaporators 42F and 42R, and the outdoor condenser 36, as already described. The refrigeration cycle circuit 30 also includes a liquid-cooled condenser 78 that exchanges heat with the heating circuit 32 and a battery cooling heat exchanger 41 that exchanges heat with the battery cooling circuit 40. In the refrigeration cycle circuit 30, adjustable-opening electric expansion valves 84 and 86 are provided upstream of the front evaporator 42F and the battery cooling heat exchanger 41, respectively. An expansion valve 88 and a solenoid valve 90 are provided upstream of the rear evaporator 42R. The electric expansion valves 84 and 86 cannot be completely closed. Even when their openings are at their smallest, a small amount of refrigerant is supplied to the front evaporator 42F and the battery cooling heat exchanger 41. On the other hand, the supply of refrigerant to the rear evaporator 42R can be completely stopped by closing the solenoid valve 90. Furthermore, a heating expansion valve 92 is provided upstream of the outdoor condenser 36. The opening of the heating expansion valve 92 is adjustable and may be an electric expansion valve. When the refrigeration cycle circuit 30 is in heating operation, the refrigerant expands as it passes through the heating expansion valve 92 with its opening reduced, and then vaporizes and absorbs heat in the outdoor condenser 36. Therefore, during heating operation, the outdoor condenser 36 functions as an evaporator. When the refrigeration cycle circuit 30 is in cooling operation, the heating expansion valve 92 is fully open, allowing the refrigerant to simply pass through. The capacity of the refrigeration cycle circuit 30 is adjusted by adjusting the output of the compressor 34 and the opening of each expansion valve 84, 86, 88, and 92.

[0026] The refrigeration cycle circuit 30 has a first bypass flow path 94 arranged in parallel with the front and rear evaporators 42F, 42R and the battery cooling heat exchanger 41. By passing through the first bypass flow path 94, the refrigerant can bypass the front and rear evaporators 42F, 42R and the battery cooling heat exchanger 41. The refrigeration cycle circuit 30 also has a second bypass flow path 96 arranged in parallel with the outdoor condenser 36, and by passing through the second bypass flow path 96, the refrigerant can bypass the outdoor condenser 36.

[0027] The battery cooling circuit 40 includes the battery 18, a battery cooling heat exchanger 41, and a battery cooling circuit pump 98 that circulates coolant between the battery 18 and the battery cooling heat exchanger 41. The battery 18 is cooled by sending coolant cooled by the battery cooling heat exchanger 41 to the battery 18. The battery 18 is provided with a battery temperature sensor 100 that detects the temperature of the battery 18, and a power storage amount sensor 102 that detects the amount of power stored in the battery 18. The level of cooling required for the battery 18 is determined based on the temperature of the battery 18, and the battery cooling circuit 40 is controlled according to the level. The power storage amount sensor 102 constantly monitors the power input and output to and from the battery 18, and calculates the current amount of power stored by integrating the input and output power.

[0028] The heating circuit 32 includes the electric heater 38, front and rear heater cores 44F, 44R, a liquid-cooled condenser 78, and a heating circuit pump 104 that supplies high-temperature liquid. The heating circuit pump 104 circulates circulating liquid through the electric heater 38, the front and rear heater cores 44F, 44R, and the liquid-cooled condenser 78. The liquid-cooled condenser 78 heats the circulating liquid in the heating circuit 32 with high-temperature refrigerant compressed by the compressor 34 of the refrigeration cycle circuit 30 to generate high-temperature liquid. The high-temperature liquid, which is the circulating liquid heated by the electric heater 38 or the liquid-cooled condenser 78, is supplied to the front and rear heater cores 44F, 44R. The heating circuit 32 also shares heating / cooling liquid with the engine cooling circuit 106, allowing the engine 14 to be used as a heat source. The operation of the three-way valve 108 determines whether the high-temperature liquid sent to the front and rear heater cores 44F, 44R is supplied from the engine 14 side or from the electric heater 38 and liquid-cooled condenser 78 side.

[0029] The engine cooling circuit 106 includes the engine 14 and the engine radiator 22, and further includes an engine cooling circuit pump 110 that circulates engine coolant between the engine 14 and the engine radiator 22. The engine cooling circuit 106 also includes a radiator bypass flow path 112 arranged in parallel with the engine radiator 22, allowing the engine coolant to circulate while bypassing the engine radiator 22. When the engine 14 is cold, such as during warm-up, the engine cooling circuit 106 circulates the engine coolant through the radiator bypass flow path 112 rather than sending it to the engine radiator 22, thereby enabling the temperature of the engine coolant to be increased quickly. As described above, the engine coolant can be shared with the fluid in the heating circuit 32.

[0030] The flow paths of the refrigerant or fluid in the refrigeration cycle circuit 30, heating circuit 32, battery cooling circuit 40, and engine cooling circuit 106 are changed according to predetermined conditions. The change in the flow path of the refrigerant or fluid is achieved by the operation of the three-way valve 108 and solenoid valve 90 already described, as well as a plurality of valves (not shown) appropriately provided in each circuit. The opening / closing and opening degree of these valves may be controlled by the control unit 60. The control unit 60 also controls the output of the compressor 34, the discharge flow rate of the battery cooling circuit pump 98, and the discharge flow rate of the heating circuit pump 104 according to requirements.

[0031] The thermal management system 12 operates in several operating modes according to predetermined conditions, which are determined based on, for example, the outside air temperature, the temperature of the airflow blown out from the air conditioner 26 based on the passenger's request (requested blowout temperature), and the cooling demand and power storage capacity of the battery 18.

[0032] FIG. 4 is a diagram showing an example of conditions that define the operating modes of the thermal management system 12, particularly the operating modes of the air conditioner 26. In the heating region H where the outdoor air temperature is below a predetermined temperature T1 (e.g., 0°C), the thermal management system 12 operates in heating mode, i.e., performs heating operation. In the cooling region C where the outdoor air temperature is higher than the predetermined temperature T1, the required discharge temperature is low, and the difference between the required discharge temperature and the outdoor air temperature is large, the thermal management system 12 operates in cooling mode, i.e., performs cooling operation. In the dehumidifying and heating regions Dp and Ds, which are intermediate between the heating region H and the cooling region C, the thermal management system 12 operates in dehumidifying and heating mode, where the air taken in by the air conditioning unit 28 is first cooled and dehumidified, and then heated to the required discharge temperature, i.e., performs dehumidifying and heating operation. The dehumidifying and heating region is further divided into a parallel dehumidifying and heating region Dp and a series dehumidifying and heating region Ds. The thermal management system 12 performs parallel dehumidifying and heating operation in the parallel dehumidifying and heating region Dp and series dehumidifying and heating operation in the series dehumidifying and heating region Ds. Parallel dehumidifying and heating operation is an operation mode in which heating is stronger than in series dehumidifying and heating operation. Furthermore, if the front air conditioning unit 28F and the rear air conditioning unit 28R can independently set their required discharge temperatures, the required discharge temperature of one of the air conditioning units 28, for example, the front air conditioning unit 28F, which has been predetermined, may be used as the factor defining the operation mode. Alternatively, the required discharge temperature of the air conditioning unit 28 set to a lower temperature may be used as the factor defining the operation mode. The operation of the thermal management system 12 in each operation mode is described below.

[0033] 5 to 7 are diagrams showing the operating states of the thermal management system 12 in the heating region H. In the following description, the front heater core 44F and the rear heater core 44R will be collectively referred to as the heater core 44 unless a particular distinction is required.

[0034] 5 is a diagram showing the operating state when the temperature of the coolant of the engine 14 is sufficiently high. When the temperature of the engine coolant is high, a portion of the engine coolant circulated by the engine cooling circuit pump 110 is supplied to the heater core 44. Depending on the operation of the occupant, the engine coolant may be supplied to either or both of the front and rear heater cores 44F, 44R.

[0035] 6 is a diagram showing the operating state when the temperature of the engine coolant is low. When the temperature of the engine coolant is low, the electric heater 38 generates high-temperature liquid, which is supplied to the heater core 44 by the heating circuit pump 104. The high-temperature liquid from the electric heater 38 may be supplied to either or both of the front and rear heater cores 44F, 44R by operation of the occupant. In addition, in a vehicle that does not have an engine 14 and runs only on power from the electric motor 16, heating is performed by the electric heater 38 or by operating the heat pump of the refrigeration cycle circuit 30, which will be described below.

[0036] FIG. 7 illustrates the operating state of the refrigeration cycle circuit 30 in heat pump mode for heating. The refrigerant compressed by the compressor 34 and heated to a high temperature is cooled and liquefied in the liquid-cooled condenser 78 by the fluid circulating through the heating circuit 32. At this time, the circulating fluid in the heating circuit 32 is heated by the high-temperature refrigerant and becomes a high-temperature liquid. The refrigerant in the refrigeration cycle circuit 30 liquefied in the liquid-cooled condenser 78 passes through the heating expansion valve 92, expands, and vaporizes in the outdoor condenser 36, absorbing heat from the outside air. In other words, the outdoor condenser 36 functions as an evaporator. The vaporized refrigerant returns to the compressor 34 through the first bypass flow path 94. The high-temperature liquid heated by the liquid-cooled condenser 78 is supplied to the heater core 44 by the heating circuit pump 104. The occupant may operate the electric heater 38 to supply high-temperature liquid to either or both of the front and rear heater cores 44F, 44R. In this heat pump operation, the passenger compartment 20 is heated by heat drawn from the outside air.

[0037] FIG. 8 is a diagram showing the operating state of the thermal management system 12 in the cooling region C. In the following description, unless a particular distinction is required, the front evaporator 42F and the rear evaporator 42R will be collectively referred to as the evaporator 42. The refrigerant compressed by the compressor 34 dissipates heat to the outside air in the outdoor condenser 36, where it is cooled and liquefied. The liquefied refrigerant expands as it passes through the electric expansion valve 84 and the expansion valve 88, and then vaporizes and absorbs heat in the front and rear evaporators 42F and 42R, respectively. This cools the passenger compartment 20. Furthermore, when there is no need to cool the rear side of the passenger compartment 20, such as when there are no passengers in the rear seats, the solenoid valve 90 may be closed to prevent refrigerant from being supplied to the rear evaporator 42R.

[0038] FIG. 9 illustrates the operating state of the thermal management system 12 in the parallel dehumidifying and heating zone Dp. The refrigerant compressed by the compressor 34 dissipates heat in the liquid-cooled condenser 78 to the circulating liquid in the heating circuit 32. This generates high-temperature liquid in the heating circuit 32 and supplies it to the heater core 44. As in the heating operation described above, high-temperature liquid may be supplied to either or both of the front and rear heater cores 44F and 44R. In parallel dehumidifying and heating operation, the amount of heat transferred through the refrigeration cycle circuit 30 is less than in heating and cooling operations using a heat pump, reducing the required capacity of the refrigeration cycle circuit 30. Therefore, the output of the compressor 34 is low, and the refrigerant that dissipates heat in the liquid-cooled condenser 78 is not completely liquefied but remains in a two-phase gas-liquid state. A portion of the refrigerant flows toward the outdoor condenser 36, passes through the throttled heating expansion valve 92, and at least a portion of the refrigerant vaporizes and absorbs heat in the outdoor condenser 36. At this time, the outdoor condenser 36 functions as an evaporator. The refrigerant that has passed through the exterior condenser 36 returns to the compressor 34 through the first bypass flow path 94. The remainder of the refrigerant that has passed through the liquid-cooled condenser 78 passes through the second bypass flow path 96 toward the evaporator 42. In the evaporator 42, at least a portion of the liquid-phase refrigerant vaporizes and absorbs heat. After passing through the evaporator 42, the refrigerant returns to the compressor 34. Furthermore, when there is no need to cool the rear side of the passenger compartment 20, such as when there are no passengers in the rear seats, the solenoid valve 90 may be closed to prevent refrigerant from being supplied to the rear evaporator 42R.

[0039] In the air conditioning unit 28, the water vapor is cooled and condensed to dehumidify the air by cooling the air in the evaporator 42. The cooled air is heated by the heater core 44, and the air conditioning unit 28 delivers warm, dry air to the passenger compartment 20.

[0040] FIG. 10 illustrates the operating state of the thermal management system 12 in the series dehumidifying and heating zone Ds. The refrigerant compressed by the compressor 34 dissipates heat to the circulating liquid in the heating circuit 32 in the liquid-cooled condenser 78. This generates high-temperature liquid for the heating circuit 32 and supplies it to the heater core 44. As in the heating operation described above, high-temperature liquid may be supplied to either or both of the front heater core 44F and the rear heater core 44R. The entire refrigerant that passes through the liquid-cooled condenser 78 is sent to the outdoor condenser 36. When the refrigerant dissipates a large amount of heat in the liquid-cooled condenser 78—that is, when heating is performed at a high level—the refrigerant absorbs heat in the outdoor condenser 36, as in the parallel dehumidifying and heating operation. By narrowing the opening of the heating expansion valve 92, a portion of the refrigerant vaporizes and absorbs heat in the outdoor condenser 36. On the other hand, when heating is performed at a low level, the refrigerant dissipates heat in the outdoor condenser 36. In this case, the heating expansion valve 92 is fully open. In the series dehumidifying and heating operation, the amount of heat transferred through the refrigeration cycle circuit 30 is smaller than in the heating and cooling operation using a heat pump, and therefore the capacity required of the refrigeration cycle circuit 30 is smaller. Therefore, the output of the compressor 34 is low, and the refrigerant that has dissipated heat in the liquid-cooled condenser 78 and the exterior condenser 36 is not completely liquefied but remains in a two-phase gas-liquid state. The two-phase gas-liquid refrigerant flows toward the evaporator 42. In the evaporator 42, the liquid refrigerant vaporizes and absorbs heat. After passing through the evaporator 42, the refrigerant returns to the compressor 34. Furthermore, when there is no need to cool the rear side of the passenger compartment 20, such as when there are no passengers in the rear seats, the solenoid valve 90 may be closed to prevent refrigerant from being supplied to the rear evaporator 42R.

[0041] In heating operation, the refrigeration cycle circuit 30 transfers heat from outside the passenger compartment 20 into the passenger compartment 20 to heat the passenger compartment 20, and in cooling operation, it transfers heat from inside the passenger compartment 20 to the outside to cool the passenger compartment. In dehumidifying and heating operation, the refrigeration cycle circuit 30 absorbs heat from the evaporator 42 and radiates heat from the heater core 44 via the heating circuit 32, thereby transferring heat within the passenger compartment 20. The difference between the amount of heat absorbed by the evaporator 42 and the amount of heat radiated by the liquid-cooled condenser 78 is absorbed or radiated by the exterior condenser 36.

[0042] In dehumidifying heating operation, heat transfer is less than in heating and cooling operation, and the output of the compressor 34 is also reduced. As a result, the refrigerant does not completely liquefy after heat dissipation and remains in a two-phase gas-liquid state. When a two-phase gas-liquid refrigerant is supplied to multiple targets, the liquid refrigerant may not be distributed evenly. When cooling the battery 18, it is necessary to reliably supply liquid refrigerant to the battery cooling heat exchanger 41. In particular, when refrigerant is supplied to both the front evaporator 42F and the rear evaporator 42R and also to the battery cooling heat exchanger 41, it may not be possible to supply a sufficient amount of liquid refrigerant.

[0043] In the thermal management system 12, when both the front and rear air conditioning units 28F, 28R are operating (dual mode) in the dehumidifying heating zones Dp, Ds, and there is a request to cool the battery 18, the refrigeration cycle circuit 30 operates in cooling mode to supply liquid refrigerant to the evaporator 42, and high-temperature liquid heated by the electric heater 38 is supplied to the heater core 44. During cooling mode operation of the refrigeration cycle circuit 30, the compressor 34 operates at high output, sufficiently compressing the refrigerant, which then dissipates heat in the outdoor condenser 36 and is completely liquefied. As a result, the required amount of liquid refrigerant is supplied to the front and rear evaporators 42F, 42R and the battery cooling heat exchanger 41.

[0044] When the demand for cooling the battery 18 increases, such as when the temperature of the battery 18 rises, the output of the compressor 34 also increases. This increases the power required to drive the compressor 34, resulting in increased power consumption. Increased power consumption shortens the driving distance possible with the electric motor 16. In this thermal management system 12, when the demand for cooling the battery 18 increases and the battery 18's charge level falls below a predetermined value, e.g., 20%, the dehumidification by the air conditioner 26 is stopped. Specifically, the supply of refrigerant to the front and rear evaporators 42F, 42R is stopped. Stopping the supply of refrigerant to the evaporator 42 reduces the output of the compressor 34 and reduces power consumption. Furthermore, because dehumidification is not performed, the temperature of the air after passing through the evaporator 42 does not decrease, and heating by the heater core 44 is reduced. This also reduces the power supplied to the electric heater 38, thereby reducing power consumption. As a result, the decrease in the amount of electricity stored in the battery 18 is suppressed, and the distance that can be traveled by the electric motor 16 can be extended.

[0045] FIG. 11 illustrates the operating state of the thermal management system 12 in the dehumidifying and heating zones Dp and Ds, where the air conditioner 26 operates in dual mode and the battery cooling circuit 40 is operating. In the refrigeration cycle circuit 30, the refrigerant compressed by the compressor 34 is sent to the outdoor condenser 36, where it dissipates heat and is completely liquefied. The liquid refrigerant is supplied to the front and rear evaporators 42F and 42R and the battery cooling heat exchanger 41. The refrigerant sent to the front and rear evaporators 42F and 42R vaporizes and absorbs heat from the air in the passenger compartment 20. The refrigerant sent to the battery cooling heat exchanger 41 vaporizes and absorbs heat from the battery coolant in the battery cooling circuit 40. Meanwhile, the battery coolant is cooled, and the cooled battery coolant is sent to the battery 18 to cool it. In the heating circuit 32, the electric heater 38 operates to generate high-temperature liquid, which is then supplied to the heater core 44. If the engine 14 coolant is hot enough, engine coolant may be supplied to the front and rear heater cores 44F, 44R.

[0046] FIG. 12 shows the operating state of the thermal management system 12 when stronger cooling of the battery 18 is required. In contrast to the operating state shown in FIG. 11, the supply of refrigerant to the front and rear evaporators 42F, 42R is stopped. The refrigerant compressed by the compressor 34 is heated to a high temperature to generate high-temperature liquid in the heating circuit 32. Because dehumidification is not performed in the air conditioning unit 28, the temperature of the air after passing through the evaporator 42 does not decrease, and reheating by the heater core 44 is unnecessary or only slight. When heating by the refrigerant in the refrigeration cycle circuit 30 is insufficient, the electric heater 38 also heats the circulating liquid in the heating circuit 32.

[0047] 13 is a diagram showing the control flow of the thermal management system 12 when both the front and rear air conditioning units 28F, 28R are performing dehumidifying and heating operation and there is also a request to cool the battery. The control unit 60 controls the thermal management system 12 in accordance with this control flow.

[0048] When the rear air conditioning switch 67 is in the ON state, i.e., the system is in dual mode in which both the front and rear air conditioning units 28F, 28R are operating (S100), and the operating condition is in the dehumidifying and heating ranges Dp, Ds (S102), the control unit 60 further determines whether battery cooling is required (S104, S106). If the battery cooling requirement is equal to or greater than a first requirement value, the control unit 60 determines that battery cooling by the battery cooling circuit 40 is necessary (S104). The battery cooling requirement is determined based on, for example, the temperature of the battery 18 detected by the battery temperature sensor 100. If the battery cooling requirement is less than the first requirement value in step S104, the process returns to the start of this control flow. If the battery cooling requirement is equal to or greater than the first requirement value, the control unit 60 further determines whether the battery cooling requirement is equal to or greater than a second requirement value (S106). The second required value corresponds to a stronger battery cooling requirement than the first required value, for example, when the battery temperature rises further. If the battery cooling requirement is less than the second required value in step S106, the control unit 60 controls the refrigeration cycle circuit 30 to perform cooling operation and the heating circuit 32 to perform heating operation (S108), as shown in Fig. 11. The control unit 60 controls the refrigeration cycle circuit 30 to send refrigerant to the battery cooling heat exchanger 41 of the battery cooling circuit 40, and further controls the battery cooling circuit 40 to send coolant cooled by the refrigerant to the battery 18 (S108).

[0049] In a situation where refrigerant is supplied to three targets, the front and rear evaporators 42F, 42R, and the battery cooling heat exchanger 41, the refrigeration cycle circuit 30 operates in cooling mode, so that only liquid-phase refrigerant can be sent to the three targets. This allows refrigerant to be supplied to the three targets more reliably than when a two-phase gas-liquid refrigerant is sent.

[0050] If the battery cooling request is equal to or greater than the second request value in step S106, the control unit 60 further determines whether the amount of stored power in the battery 18 is less than a predetermined value, for example, less than 20% (S110). If the amount of stored power is equal to or greater than the predetermined value, the process proceeds to step S108. If the amount of stored power is less than the predetermined value, the control unit 60 stops dehumidifying the air conditioner 26 (S112). Specifically, as shown in FIG. 12, the control unit 60 controls the refrigeration cycle circuit 30 to stop the supply of refrigerant to the front and rear evaporators 42F, 42R. The refrigeration cycle circuit 30 supplies refrigerant only to the battery cooling heat exchanger 41. The heating circuit 32 supplies high-temperature liquid to the front and rear heater cores 44F, 44R as needed.

[0051] Stopping dehumidification suppresses an increase in the output of the compressor 34 and also suppresses the reheating of the air in the air conditioning unit 28. This reduces the power consumption of the battery 18 and extends the distance that can be traveled by the electric motor 16. [Explanation of symbols]

[0052] 10 vehicle, 12 thermal management system, 14 engine, 16 electric motor, 18 battery, 20 passenger compartment, 22 engine radiator, 26 air conditioning device, 28 air conditioning unit, 28F front air conditioning unit, 28R rear air conditioning unit, 30 refrigeration cycle circuit, 32 heating circuit, 34 compressor, 36 outdoor condenser, 38 electric heater, 40 battery cooling circuit, 41 battery cooling heat exchanger, 42 evaporator, 42F front evaporator, 42R rear evaporator, 44 heater core, 44F front heater core, 44R rear heater core, 60 control unit, 78 liquid-cooled condenser, 84, 86 electric expansion valve, 88 expansion valve, 90 solenoid valve, 92 heating expansion valve, 94 first bypass flow path, 96 second bypass flow path, 98 Battery cooling circuit pump, 100 battery temperature sensor, 102 battery charge sensor, 104 heating circuit pump, 106 engine cooling circuit, 108 three-way valve.

Claims

1. A front air conditioning unit that conditions air in a front space of a passenger compartment of a vehicle; A rear air conditioning unit that conditions air in a rear space of the passenger compartment; a battery cooling circuit that circulates a coolant that cools a battery that supplies power to an electric motor for driving the vehicle; a refrigeration cycle circuit that supplies a refrigerant to the front air conditioning unit and the rear air conditioning unit, and also supplies a refrigerant to a battery cooling heat exchanger that exchanges heat between a cooling liquid in the battery cooling circuit and the refrigerant; a heating circuit that generates a high-temperature liquid using a heat source or a refrigerant in the refrigeration cycle circuit and supplies the high-temperature liquid to the front air conditioning unit and the rear air conditioning unit; A vehicle thermal management system comprising: In a dehumidifying and heating operation region determined based on a required blowing temperature, which is a control target for the temperature of air blown out from the front air conditioning unit and the rear air conditioning unit, and an outside air temperature, when the front air conditioning unit and the rear air conditioning unit are in an operating state and a cooling requirement for the battery is equal to or greater than a first required value, the refrigeration cycle circuit performs a cooling operation and supplies a refrigerant to the front air conditioning unit, the rear air conditioning unit, and the battery cooling heat exchanger; The heating circuit generates a high-temperature liquid using the heat source, the battery cooling circuit cools the battery with a coolant cooled by a refrigerant in the battery cooling heat exchanger of the refrigeration cycle circuit, Vehicle thermal management system.

2. 2. A vehicle thermal management system as described in claim 1, wherein when the cooling requirement of the battery is equal to or greater than a second requirement value higher than the first requirement value and the amount of charge stored in the battery is lower than a predetermined value, the supply of refrigerant to the front air conditioning unit and the rear air conditioning unit by the refrigeration cycle circuit is stopped.

3. 3. A vehicle thermal management system according to claim 1 or 2, wherein the refrigeration cycle circuit has a compressor that compresses a refrigerant and an exterior heat exchanger that exchanges heat with outside air, and during the cooling operation, the entire amount of the refrigerant compressed and discharged by the compressor passes through the exterior heat exchanger and is liquefied.

4. 3. The vehicle thermal management system according to claim 1 or 2, wherein the heat source of the heating circuit is one or both of an engine that drives the vehicle and an electric heater.

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