THERMAL MANAGEMENT SYSTEM FOR A BATTERY-ELECTRIC VEHICLE

Abstract

Thermal management system (2) for a battery electric vehicle with: a power supply unit (3) that supplies an electric motor (4) for driving, a power supply cooler (11) which cools the power supply unit (3) with a heat medium, an air conditioning system (20) that heats a vehicle interior with the heat of the heat medium, an outdoor air heat exchanger (13) that exchanges heat between the heat medium and the outdoor air, a circulation path (10) that connects the power supply cooler (11), the air conditioning unit (20) and the outdoor air heat exchanger (13) and through which the heat medium flows, a switching valve (14) arranged in the circulation path (10), wherein the switching valve (14) is configured to be selectively switchable between a first valve position and a second valve position, and the switching valve (14) is configured such that the heat medium circulates between the air conditioning unit (20) and the power supply cooler (11) and the flow of the heat medium between the air conditioning unit (20) and the outdoor air heat exchanger (13) is interrupted when the switching valve (14) is in the first valve position, and the heat medium circulates between the air conditioning unit (20) and the outdoor air heat exchanger (13) and the flow of the heat medium between the air conditioning unit (20) and the power supply cooler (11) is interrupted when the switching valve (14) is in the second valve position, a control unit (30) configured to control the switching valve (14), wherein the control unit (30) is configured to operate in a heating mode in which the air conditioner (20) is operated, The switching valve (14) switches to the first valve position when a power supply temperature, which is a temperature of the power supply unit (3), is higher than a predetermined power supply temperature limit, and the switching valve (14) switches to the second valve position when the power supply temperature is less than or equal to the predetermined power supply temperature limit, and The switching valve (14) switches from the first valve position to the second valve position independently of the power supply temperature when the temperature of the heat medium flowing through the power supply cooler (11) is lower than the outside air temperature by a predetermined temperature difference range or more while the switching valve (14) is in the first valve position.

Description

BACKGROUND OF THE INVENTION 1. Technical field of the invention

[0001] The teaching disclosed herein relates to a thermal management system for a battery electric vehicle. 2. State of the art

[0002] Thermal management systems exist that utilize the heat of the outside air to heat a vehicle interior. An example of such a thermal management system is disclosed in JP 2012-158 197 A. JP 2020-200 943 A discloses a switching valve for a circulation path in which cooling water flows, wherein the switching valve is configured to be selectively switchable between a first valve position and a second valve position, and the switching valve is configured such that a heating medium circulates between one group of inlets and outlets and a flow of the heating medium between another group of inlets and outlets is interrupted when the switching valve is in a first valve position, and the heating medium circulates between inlets and outlets of the other group and the flow of the heating medium between the inlets and outlets of one group is interrupted when the switching valve is in the second valve position. SUMMARY OF THE INVENTION

[0003] A battery-electric vehicle is equipped with a power supply that supplies electrical power to an electric motor for propulsion. The heat from the power supply can also be used to heat the vehicle interior. The present disclosure provides a thermal management system that can efficiently utilize the heat from a power supply and the heat from the outside air to heat the vehicle interior.

[0004] A thermal management system according to one aspect of the present invention includes a power supply that supplies electric power to an electric motor for propulsion, a power supply cooler that cools the power supply via a heat medium, a heating element that heats a vehicle interior with heat from the heat medium, an outside air heat exchanger that exchanges heat between the heat medium and the outside air, a circulation path that connects the power supply cooler, the heating element, and the outside air heat exchanger, a switching valve disposed in the circulation path, and a control unit configured to control the switching valve. The switching valve is configured to switch between a first valve position and a second valve position.When the switching valve is in the first valve position, the heat medium circulates between the heating element and the power supply cooler, and the flow of the heat medium is interrupted between the heating element and the outside air heat exchanger. When the switching valve is in the second valve position, the heat medium circulates between the heating element and the outside air heat exchanger, and the flow of the heat medium is interrupted between the heating element and the power supply cooler.

[0005] The control unit is configured to switch the switching valve to the first valve position in a heating mode in which the heating element is operated when a power supply temperature, which is a temperature of the power supply, is higher than a predetermined power supply temperature limit, and to switch the switching valve to the second valve position when the power supply temperature is less than or equal to the power supply temperature limit. The control unit is configured to switch the switching valve from the first valve position to the second valve position, regardless of the power supply temperature, when a temperature of the heat medium that has flowed through the power supply cooler is lower than the outside air temperature by a predetermined temperature difference margin or more while the switching valve is in the first valve position.

[0006] When the power supply temperature is higher than the power supply temperature limit, the first valve position is selected (i.e., the switching valve is in the first valve position), and the heat medium circulates between the heating element and the power supply cooler. The heat medium absorbs the heat from the high-temperature power supply and heats the air in the vehicle interior through the heating element. When the power supply temperature is high, the heat from the power supply is used for heating.

[0007] On the other hand, when the power supply temperature is less than or equal to the power supply temperature limit, the second valve position is selected (i.e., the switching valve is in the second valve position), and the heat medium circulates between the heating element and the outside air heat exchanger. The heat medium absorbs heat from the outside air and heats the air in the vehicle interior through the heating element. When the power supply temperature is low, the heat from the outside air is used for heating. A heat pump mechanism can be used to transfer the heat from the power supply or the outside air into the vehicle interior. The heat pump mechanism is described in one embodiment.

[0008] The control unit switches the switching valve from the first valve position to the second valve position, regardless of the power supply temperature, when the temperature of the heat medium that has passed through the power supply cooler is lower than the outside air temperature by the specified temperature difference margin or more while the switching valve is in the first valve position. For example, heat may not be transferred well from the power supply to the heat medium if the heat transfer layer sandwiched between the power supply and the power supply cooler deteriorates, or if a gap occurs between the power supply and the power supply cooler due to vehicle vibration.Even if the power supply temperature is not low, the control unit switches to heating using the outside air heat if the heat transfer from the power supply to the heating medium is poor. By controlling the switching valve in this way, the heat from the power supply and the outside air heat can be efficiently used to heat the vehicle interior.

[0009] The control unit can be configured to hold the switching valve in the second valve position for at least a predetermined holding time, regardless of the power supply temperature, if the temperature of the heat medium that has flowed through the power supply cooler is below the outside air temperature by the temperature difference range or more. Undesirable fluctuation or hunting of the valve position when switching the switching valve position can thus be prevented.

[0010] Details and further improvements of the teachings disclosed herein are described below in the "DETAILED DESCRIPTION OF THE EMBODIMENTS" section. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Features, advantages and technical and industrial significance of exemplary embodiments of the invention are described below with reference to the accompanying drawings, in which like reference numerals designate like elements, and wherein: Fig. 1 is a thermal circuit diagram of a thermal management system of an embodiment (first valve position), Fig. 2 is a thermal circuit diagram of a thermal management system of an embodiment (second valve position), Fig. 3 is a flowchart of a process performed by the control unit during heating, and Fig. 4 is a thermal diagram of an air conditioning system. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0012] A thermal management system 2 of an embodiment will be described with reference to the drawings. Fig. 1 is a thermal circuit diagram of the thermal management system 2. In the embodiment, the “thermal circuit” means a circuit of a flow path through which a thermal medium flows.

[0013] The thermal management system 2 is mounted on a battery-electric vehicle. The thermal management system 2 adjusts the temperature of a vehicle interior and maintains the temperatures of a power supply unit 3 (referred to briefly as the power supply 3), an electric motor 4 (referred to briefly as the motor) for driving, and a power converter 5 within their appropriate temperature ranges. The electrical current of the power supply 3 is converted by the power converter 5 into alternating current (AC), which is suitable for driving the motor 4 and is supplied to the motor 4. The power supply 3 is typically a battery, such as a lithium-ion battery, or a fuel cell, but can also be another type of power supply. The power lines are in Fig. 1 not shown.

[0014] The thermal management system 2 includes a circulation path 10 through which a heat medium flows, a power supply cooler 11 configured to cool the power supply 3, an electric motor cooler 12 (hereinafter referred to as an engine cooler) configured to cool the engine 4, an outside air heat exchanger 13 configured to exchange heat between the heat medium and outside air, an air conditioner 20 configured to adjust the temperature of the vehicle interior, pumps 15, 16 configured to convey the heat medium, and a switching valve 14 configured to switch the flow path for the heat medium.

[0015] The circulation path 10 is a pipe that connects the power supply cooler 11, the engine cooler 12, the outside air heat exchanger 13, the air conditioner 20, and the switching valve 14, and circulates the heat medium between the coolers and the air conditioner. For convenience, the circulation path 10 is divided into the following flow paths: an air conditioner flow path 10a passing through the air conditioner 20, a heat exchanger flow path 10b passing through the outside air heat exchanger 13, a power supply cooler flow path 10c passing through the power supply cooler 11, an engine cooler flow path 10d passing through the engine cooler 12, and a bypass flow path 10e. The engine cooler flow path 10d also passes through a power converter cooler 17 configured to cool the power converter 5.

[0016] The air conditioning system 20 adjusts the temperature of the vehicle interior. The air conditioning system 20 operates in two modes, which include a cooling mode in which the air conditioning system 20 cools the vehicle interior, and a heating mode in which the air conditioning system 20 heats the vehicle interior. The air conditioning system 20 is in Fig. 1 is shown in simplified form. The structure of the air conditioning system 20 will be described in detail later.

[0017] The power supply cooler 11 cools the power supply 3. The heat medium flowing through the power supply cooler 11 absorbs the heat of the power supply 3 to cool the power supply 3.

[0018] The outside air heat exchanger 13 includes a fan 13a. The outside air introduced into the outside air heat exchanger 13 by the fan 13a exchanges heat with the heat medium flowing through the outside air heat exchanger 13. The outside air heat exchanger 13 is generally referred to as a radiator, but in the present embodiment, it is referred to as an outside air heat exchanger because it can transfer heat from the outside air to the heat medium.

[0019] The engine cooler 12 includes an oil cooler 91, an oil pump 92, and an oil flow path 93. The engine cooler flow path 10d passes through the oil cooler 91. The oil flow path 93 passes through the oil cooler 91 and the engine 4. The oil flows through the oil flow path 93. The oil pump 92 is located in the oil flow path 93 and circulates the oil between the oil cooler 91 and the engine 4. The engine 4 is cooled by the heat medium flowing through the circulation path 10. More specifically, the heat medium cools the oil in the oil cooler 91, and the cooled oil cools the engine 4. The heat of the engine 4 is absorbed by the heat medium via the oil.

[0020] The thermal management system 2 includes temperature sensors 94a, 94b, and 94c. Temperature sensor 94a measures the temperature of the power supply 3. Temperature sensor 94b is located in the power supply cooler flow path 10c and measures the temperature of the heat medium that has flowed through the power supply cooler 11. Temperature sensor 94c is attached to the outside air heat exchanger 13 and measures the temperature of the outside air introduced into the outside air heat exchanger 13. The thermal management system 2 includes additional temperature sensors, which are not described here.

[0021] The measured values ​​of the temperature sensors 94a to 94c are transmitted to a control unit 30. The control unit 30 controls the pumps 15, 16, the oil pump 92, and the switching valve 14 based on the measured values ​​of the temperature sensors 94a to 94c. The control unit 30 is, for example, an electronic control unit with a processor.

[0022] First ends of the air conditioning flow path 10a, the heat exchanger flow path 10b, the power supply cooler flow path 10c, the engine cooler flow path 10d, and the bypass flow path 10e are connected to the switching valve 14. The switching valve 14 switches the connection between the air conditioning flow path 10a, the heat exchanger flow path 10b, the power supply cooler flow path 10c, the engine cooler flow path 10d, and the bypass flow path 10e. The connection between the flow paths by the switching valve 14 will be described in detail later. Second ends of the air conditioning flow path 10a, the heat exchanger flow path 10b, the power supply cooler flow path 10c, the engine cooler flow path 10d, and the bypass flow path 10e are connected by a plurality of three-way valves 95. The pumps 15, 16 are located in the circulation path 10.Pump 15 is located upstream of the air conditioner 20 in the air conditioner flow path 10a, and pump 16 is located upstream of the engine cooler 12 in the engine cooler flow path 10d. The arrows along the flow paths indicate the flow direction of the heat medium. Pumps 15, 16 force the heat medium to flow toward the switching valve 14. The flow path for the heat medium is determined according to the state of the switching valve 14. The flow directions of the heat medium in the three-way valves 95 are determined depending on the flow path for the heat medium.

[0023] The switching valve 14 can be selectively switched between a first valve position and a second valve position (ie, the valve position of the switching valve 14 can be selected between the first valve position and the second valve position). Fig. 1 shows the flow of the heat medium when the switching valve 14 is in the first valve position. When the switching valve 14 is in the first valve position, it connects the air conditioning flow path 10a with the power supply cooler flow path 10c and the heat exchanger flow path 10b with the engine cooler flow path 10d. At this time, the heat medium circulates between the air conditioning system 20 and the power supply cooler 11, and also between the engine cooler 12 and the outside air heat exchanger 13. When the switching valve 14 is in the first valve position, the heat medium circulating between the air conditioning system 20 and the power supply cooler 11 and the heat medium circulating between the engine cooler 12 and the outside air heat exchanger 13 do not mix with each other.In other words, when the switching valve 14 is in the first valve position, the heat medium circulates between the air conditioner 20 and the power supply cooler 11, and the flow of the heat medium is interrupted between the air conditioner 20 and the outside air heat exchanger 13.

[0024] Fig. 2 shows the flow of the heat medium when the switching valve 14 is in the second valve position. When the switching valve 14 is in the second valve position, it connects the air conditioning flow path 10a with the heat exchanger flow path 10b and connects the engine cooling radiator flow path 10d with the bypass flow path 10e. At this time, the heat medium circulates between the air conditioning system 20 and the outside air heat exchanger 13, and also between the engine cooling radiator 12 and the bypass flow path 10e. When the switching valve 14 is in the second valve position, the heat medium circulating between the air conditioning system 20 and the outside air heat exchanger 13 and the heat medium in the power supply radiator 11 do not mix with each other.In other words, when the switching valve 14 is in the second valve position, the heat medium circulates between the air conditioner 20 and the outside air heat exchanger 13, and the flow of the heat medium between the air conditioner 20 and the power supply cooler 11 is interrupted.

[0025] When the heating mode is selected, the air conditioning system 20 heats the vehicle interior as described above. The heat from the power supply 3 or the heat from the outside air is used to heat the vehicle interior.

[0026] Fig. 3 is a flowchart of a process performed by the control unit 30 during heating. If a timer is operating in step S2, the control unit 30 compares the elapsed time indicated by the timer with a predetermined hold time (step S2: YES, S3). The timer is a variable defined in a program executed by the control unit 30 and measures the elapsed time since the timer was started. The timer is started in step S9, which will be described later. Since the timer is normally stopped, the determination result of step S2 is "NO," and the routine of the control unit 30 proceeds to step S5. A condition for starting the timer will be described later.

[0027] The control unit 30 compares the power supply temperature with a power supply temperature threshold (step S5). The power supply temperature is detected by the temperature sensor 94a attached to the power supply 3. The control unit 30 controls the switching valve 14 to select the first valve position when the power supply temperature is higher than the power supply temperature threshold (step S5: YES, S6). The control unit 30 controls the switching valve 14 to select the second valve position when the power supply temperature is less than or equal to the power supply temperature threshold (step S5: NO, S7).

[0028] As in Fig. As shown in Figure 1, the heat medium circulates between the air conditioner 20 and the power supply cooler 11 when the first valve position is selected (i.e., when the switching valve 14 is in the first valve position). At this time, the movement of the heat medium between the air conditioner 20 and the outside air heat exchanger 13 is blocked. The heat medium, which has absorbed the heat from the power supply 3 in the power supply cooler 11, releases the heat to the air conditioner 20 while flowing through the air conditioner 20. The air conditioner 20 uses the heat from the power supply 3 to heat the vehicle interior.

[0029] As in Fig. As shown in Figure 2, when the second valve position is selected (that is, when the switching valve 14 is in the second valve position), the heat medium circulates between the air conditioner 20 and the outside air heat exchanger 13. At this time, the movement of the heat medium between the air conditioner 20 and the power supply cooler 11 is blocked. The heat medium, which has absorbed the heat of the outside air in the outside air heat exchanger 13, releases the heat to the air conditioner 20 while passing through the air conditioner 20. The air conditioner 20 uses the heat of the outside air to heat the vehicle interior. The air conditioner 20 uses a heat pump mechanism to transfer heat from the power supply 3 or the outside air to the vehicle interior. The structure of the air conditioner 20 will be described later.

[0030] As described above, the thermal management system 2 heats the vehicle interior with the heat of the power supply 3 when the temperature of the power supply 3 is high, and heats the vehicle interior with the heat of the outside air when the temperature of the power supply 3 is low.

[0031] However, as described below, even at a high power supply temperature, the thermal management system 2 switches to heating using outside air heat if the heat is not well transferred from the power supply 3 to the heat medium. For example, if the heat transfer film sandwiched between the power supply and the power supply cooler deteriorates, or if a gap develops between the power supply and the power supply cooler due to vehicle vibration, the heat may not be well transferred from the power supply to the heat medium.

[0032] After selecting the first valve position in step S6, the control unit 30 compares the temperature of the heat medium that has flowed through the power supply cooler 11 with the outside air temperature (step S8). The temperature of the heat medium that has flowed through the power supply cooler 11 is detected by the temperature sensor 94b located downstream of the power supply cooler 11, and the outside air temperature is detected by the temperature sensor 94c attached to the outside air heat exchanger 13.

[0033] If the temperature of the heat medium that has flowed through the power supply cooler 11 is lower than the outside air temperature by a predetermined temperature difference margin or more (step S8: YES), the control unit 30 switches the switching valve 14 from the first valve position to the second valve position regardless of the power supply temperature (step S9). The control unit 30 maintains the switching valve 14 in the first valve position if the temperature of the heat medium that has flowed through the power supply cooler 11 is not lower than the outside air temperature by the predetermined temperature difference margin or more (step S8: NO).

[0034] When the switching valve 14 is set to the second valve position, as described above, the heat of the outside air is used to heat the vehicle interior. The temperature difference margin is set to, for example, 5 degrees. When the temperature of the heat medium that has flowed through the power supply cooler 11 is 5 degrees or more lower than the outside air temperature, the control unit 30 switches from heating using the heat of the power supply (first valve position) to heating using the heat of the outside air (second valve position). That is, when the temperature of the heat medium supplied to the air conditioner 20 drops below the outside air temperature by the temperature difference margin or more while the switching valve 14 is in the first valve position, the control unit 30 switches the switching valve 14 to the second valve position to switch to heating using the heat of the outside air.

[0035] If the determination result in step S8 is YES, the control unit 30 starts the timer and ends the process of Fig. 3 (step S9). If the determination result in step S8 is NO, the control unit 30 stops the timer and ends the process (step S10). The control unit 30 resets the timer value to zero at the same time the control unit 30 stops the timer.

[0036] The control unit 30 repeats the process of Fig. 3 at regular intervals. After the timer starts in step S9, the switching valve 14 is held in the second valve position regardless of the power supply temperature until the predetermined holding time elapses (step S2: YES, step S3: YES, return). On the other hand, if the predetermined holding time has elapsed since the timer started in step S9, the timer is stopped, and step S5 and the following steps are executed (steps S2: YES, S3: NO, S4). As in step S10, the control unit 30 resets the timer value to zero at the same time that the control unit 30 stops the timer in step S4.

[0037] After the switching valve 14 is switched from the first valve position to the second valve position in step S9, the switching valve 14 is held in the second valve position for a specified holding time. This process fixes the valve position even when the power supply temperature, the heating medium temperature, or the outside air temperature changes slightly. This prevents undesirable fluctuation or oscillation of the valve position when switching the position of the switching valve 14. The holding time is set to 5 minutes, for example.

[0038] In the thermal management system 2 of the present embodiment, even at a high power supply temperature, the thermal management system 2 switches from heating with the heat of the power supply 3 to heating with the heat of the outside air when the heat is not well transferred from the power supply 3 to the heat medium (that is, when the temperature of the heat medium that has passed through the power supply cooler 11 is low). By controlling the switching valve 14 in this way, the heat of the power supply 3 and the heat of the outside air can be efficiently utilized for heating the vehicle interior.

[0039] The structure of the air conditioning system 20 is described with reference to Fig.4. The air conditioning system 20 includes a first thermal circuit 40 and a second thermal circuit 50. The first thermal circuit 40 cools the vehicle interior, and the second thermal circuit 50 heats the vehicle interior. The first thermal circuit 40 also serves to transfer the heat of the heat medium flowing through the circulation path 10 to the second thermal circuit 50 during heating. For convenience, the thermal circuit that circulates the heat medium between the outside air heat exchanger 13 (or the power supply cooler 11) and the air conditioning system 20 (i.e., the circulation path 10 and the devices connected to the circulation path 10) is hereinafter referred to as the main thermal circuit.

[0040] The first thermal circuit 40 includes a circulation path 41, a chiller 42, an evaporator 43, expansion valves 44a, 44b, a compressor 45, a heat exchanger 47, a switching valve 46, and a modulator 48. The circulation path 41 connects the chiller 42, the evaporator 43, and the heat exchanger 47. A first heat medium flows through the circulation path 41. The switching valve 46 switches the flow path for the first heat medium. In heating mode, the control unit 30 controls the switching valve 46 so that the first heat medium circulates between the chiller 42 and the heat exchanger 47 and that the first heat medium does not flow to the evaporator 43.

[0041] The first heat medium, which is a liquid, becomes a gas, and its temperature drops as it flows through the expansion valve 44a. The first heat medium with the lowered temperature absorbs heat from the heat medium of the main thermal circuit and increases its temperature as it flows through the refrigeration machine 42. The first heat medium (gas), which has flowed through the refrigeration machine 42, is compressed and liquefied, and its temperature further increases as it flows through the compressor 45. This high-temperature first heat medium is supplied to the heat exchanger 47. The first heat medium, which has flowed through the heat exchanger 47, is directed to the switching valve 46 via the modulator 48.

[0042] The second thermal circuit 50 comprises a circulation path 51, a vehicle interior heating element 53, a radiator 56, and a switching valve 52. The circulation path 51 connects the heat exchanger 47, a vehicle interior heating element 53, and the radiator 56. A second heat medium flows through the circulation path 51. The switching valve 52 switches the flow path for the second heat medium. In heating mode, the control unit 30 controls the switching valve 52 so that the second heat medium circulates between the heat exchanger 47 and the vehicle interior heating element 53 and so that the second heat medium does not flow to the radiator 56.

[0043] As described above, the first high-temperature heat medium flows to the heat exchanger 47. In the heating mode, the second heat medium absorbs heat from the first heat medium while flowing through the heat exchanger 47. The second heat medium, with an increased temperature due to the heat of the first heat medium, flows through the vehicle interior heating element 53. An air duct 53a, through which air flows into the vehicle interior, also passes through the vehicle interior heating element 53. The vehicle interior heating element 53 heats the air in the vehicle interior with the high-temperature second heat medium. When the second heat medium has low thermal energy, the control unit 30 heats the second heat medium using an electric heating element 54. In the heating mode, the heat from the power supply 3 or the heat from the outside air heats the vehicle interior through the heat medium of the main thermal circuit via the first heat medium and the second heat medium.In the first thermal circuit 40, the first heat medium, which has evaporated and whose temperature has decreased, absorbs heat from the heat medium of the main thermal circuit, and the first heat medium, which has been compressed and liquefied and whose temperature has further increased, releases heat to the second heat medium. Through this circuit, heat can be transferred between the power supply 3 (or the outside air) and the vehicle interior, between which there is a small temperature difference. This heat transfer circuit between two heat circuits with a small temperature difference between them is called a heat pump.

[0044] In cooling mode, the control unit 30 controls the switching valve 46 so that the first heat medium circulates between the evaporator 43 and the heat exchanger 47, and so that the first heat medium does not flow to the refrigeration unit 42. An air duct 43a, through which air flows into the vehicle interior, also passes through the evaporator 43. The first heat medium, which is liquid, transforms into a gas and decreases in temperature as it passes through the expansion valve 44a. The first heat medium with the reduced temperature cools the air in the vehicle interior as it flows through the first evaporator 43. The first heat medium (gas), which has flowed through the evaporator 43, is compressed and liquefied, and its temperature increases as it flows through the compressor 45. The high-temperature first heat medium is supplied to the heat exchanger 47 and transfers heat to the second heat medium in the second thermal circuit 50.In cooling mode, the control unit 30 controls the switching valve 52 so that the second heat medium circulates between the heat exchanger 47 and the radiator 56 in the second thermal circuit 50, and so that the second heat medium does not flow to the vehicle interior heating element 53. The heat of the second heat medium is dissipated to the outside air via the radiator 56. The first heat medium cooled by the heat exchanger 47 is passed to the switching valve 46 via the modulator 48, where it evaporates and decreases in temperature as it flows through the expansion valve 44b.

[0045] As described above, the thermal management system 2 can efficiently use the heat from the power supply and the heat from the outside air to heat the vehicle interior.

[0046] Points to note regarding the teachings described in the embodiment will be described. The air conditioner 20 in heating mode is an example of the heating element that heats the vehicle interior.

[0047] While specific examples of the invention have been described in detail above, these examples are merely illustrative and are not intended to limit the scope of the disclosure. The technology defined in the disclosure includes various modifications and alterations of the specific examples shown above. The technical elements shown in the present description or the drawings have technical benefits alone or in various combinations and are not limited to the combinations described in the originally filed disclosure. The technology shown in the present description or the drawings can achieve multiple objects at the same time and has technical benefits by achieving one of the objects.

Claims

[1] Thermal management system (2) for a battery electric vehicle with: a power supply unit (3) which supplies an electric motor (4) with electric power for driving, a power supply cooler (11) which cools the power supply unit (3) with a heat medium, an air conditioning system (20) which heats a vehicle interior with the heat of the heat medium, an outside air heat exchanger (13) which exchanges heat between the heat medium and the outside air, a circulation path (10) connecting the power supply cooler (11), the air conditioning system (20) and the outside air heat exchanger (13) and through which the heat medium flows, a switching valve (14) arranged in the circulation path (10), wherein the switching valve (14) is configured to be selectively switchable between a first valve position and a second valve position, and the switching valve (14) is configured such that the heat medium circulates between the air conditioner (20) and the power supply cooler (11) and a flow of the heat medium between the air conditioner (20) and the outside air heat exchanger (13) is interrupted when the switching valve (14) is in the first valve position, and the heat medium circulates between the air conditioner (20) and the outside air heat exchanger (13) and the flow of the heat medium between the air conditioner (20) and the power supply cooler (11) is interrupted when the switching valve (14) is in the second valve position, a control unit (30) configured to control the switching valve (14), wherein the control unit (30) is configured to operate in a heating mode in which the air conditioner (20) is operated, the switching valve (14) switches to the first valve position when a power supply temperature, which is a temperature of the power supply unit (3), is higher than a predetermined power supply temperature limit, and the switching valve (14) switches to the second valve position when the power supply temperature is less than or equal to the predetermined power supply temperature limit, and the switching valve (14) switches from the first valve position to the second valve position regardless of the power supply temperature when a temperature of the heat medium that has flowed through the power supply cooler (11) is lower than an outside air temperature by a predetermined temperature difference range or more while the switching valve (14) is in the first valve position. [2] Thermal management system according to claim 1, wherein the control unit (30) is configured to hold the switching valve (14) in the second valve position for at least a predetermined holding time regardless of the power supply temperature when the temperature of the heat medium that has flowed through the power supply cooler (11) is lower than the outside air temperature by the predetermined temperature difference range or more. [3] Thermal management system according to claim 1, wherein the predetermined temperature difference range is 5 degrees. [4] Thermal management system according to claim 2 or 3, wherein the predetermined holding time is 5 minutes.

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