Heat management device of vehicle

Abstract

To prevent a refrigerant flowing into a refrigeration cycle compressor from being brought into a liquid phase state or an air / liquid mixed phase state while suppressing the lowering of a heating capacity when a temperature of a low-temperature side heat medium flowing into a chiller is lowered.SOLUTION: When a temperature difference ΔT (=Tb-Tr) between a temperature Tb of a low-temperature side heat medium before switching detected by a temperature sensor 12 and a temperature Tr of the low-temperature side heat medium after the switching is equal to or higher than a prescribed value α when a five-way valve 310 is switched to a third connection pattern (P1 and P5 are connected, and P3 and P4 are connected) from a first connection pattern (P1 and P2 are connected, and P3 and P4 are connected) at the heating of an air conditioner 2, a refrigerant flowing out of a chiller 160 and flowing into a compressor 151 is heated by an electric heater 300.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to vehicle thermal management systems. [Background technology]

[0002] JP 2020-165604 A (Patent Document 1) discloses a refrigeration cycle device applied to an air conditioner for an electric vehicle. In this refrigeration cycle device, the heat of a battery and the outside air absorbed by a chiller arranged in a refrigeration cycle (heat pump cycle) is used to heat the vehicle interior. The heat of the battery and the outside air is absorbed in the chiller by a low-temperature side heat medium circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-165604 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the refrigeration cycle device of Patent Document 1, when cooling of the battery by the low-temperature side heat medium circuit (low-temperature side circuit) is stopped, the amount of heat absorbed from the battery decreases, the temperature of the low-temperature side heat medium flowing into the chiller drops sharply, and the refrigerant flowing into the compressor of the refrigeration cycle becomes liquid phase or a gas-liquid mixed phase state, causing a malfunction of the compressor. In Patent Document 1, when cooling of the battery by the low-temperature side circuit is stopped, the rotation speed of the compressor is reduced to suppress the occurrence of liquid backflow, in which liquid phase refrigerant flows into the compressor.

[0005] If the compressor rotation speed is reduced, the amount of refrigerant flowing into the chiller will decrease, which could result in a decrease in the amount of heat absorbed by the chiller and a decrease in heating capacity.

[0006] The object of the present disclosure is to prevent the refrigerant flowing into the compressor of the refrigeration cycle from becoming liquid phase or a gas-liquid mixed phase state while suppressing a decrease in heating capacity when the temperature of the low-temperature side heat medium flowing into a chiller drops. [Means for solving the problem]

[0007] The vehicle thermal management device according to the present disclosure is a vehicle thermal management device including a refrigeration cycle, a low-temperature side circuit, and an air conditioner. The refrigeration cycle includes a compressor that compresses and discharges a refrigerant flowing out of a chiller, a condenser that dissipates heat from the refrigerant discharged from the compressor, and a pressure reducing section that reduces the pressure of the refrigerant flowing out of the condenser. The chiller exchanges heat between the refrigerant depressurized in the pressure reducing section and a low-temperature side heat medium. The low-temperature side circuit includes a heat exchanger that absorbs heat from a battery, heat from a vehicle drive device, and heat from outside air into the low-temperature side heat medium. The air conditioner performs heating by utilizing the heat dissipated by the condenser. The thermal management device further includes an electric heater that heats the refrigerant flowing out of the chiller and flowing into the compressor, or a bypass passage that allows the refrigerant discharged from the compressor to flow into the compressor. When the air conditioner is heating, when the heat exchanger in the low-temperature side circuit that causes the low-temperature side heat medium to absorb heat is switched, if the temperature of the low-temperature side heat medium flowing into the chiller after the heat exchanger is switched is lower by a predetermined value or more than the temperature of the low-temperature refrigerant flowing into the chiller before the switch, the electric heater is turned on or the refrigerant is circulated through a bypass passage.

[0008] According to this configuration, the refrigerant in the refrigeration cycle absorbs heat from the low-temperature heat medium that has absorbed the heat of the battery, the heat of the vehicle drive device, and the heat of the outside air in the chiller, and dissipates the heat in the condenser to be used for heating. In this way, the heat of the battery, the heat of the vehicle drive device, and the heat of the outside air are used for heating.

[0009] During heating, when the heat exchanger in the low-temperature side circuit that causes the low-temperature side heat medium to absorb heat is switched, if the temperature of the low-temperature side heat medium flowing into the chiller after the heat exchanger is switched becomes lower than the temperature of the low-temperature refrigerant flowing into the chiller before the switch, the amount of heat absorbed by the refrigerant will decrease, raising the concern that the refrigerant flowing into the compressor will become liquid phase or a gas-liquid mixed phase.

[0010] According to the above configuration, during heating, when the heat exchanger that absorbs heat into the low-temperature heat medium in the low-temperature side circuit is switched, if the temperature of the low-temperature side heat medium flowing into the chiller after the heat exchanger is switched is lower than the temperature of the low-temperature side heat medium flowing into the chiller before the switch by a predetermined value or more, an electric heater that heats the refrigerant flowing out of the chiller and into the compressor is energized, or a bypass passage that allows the refrigerant discharged from the compressor to flow into the compressor is used to return the refrigerant to the compressor. This makes it possible to compensate for the decrease in the amount of heat absorbed by the refrigerant and to prevent the refrigerant flowing into the compressor from becoming liquid phase or gas-liquid mixed phase. In addition, it is possible to maintain the amount of refrigerant required for heating, and to prevent a decrease in heating capacity. Effect of the Invention

[0011] According to the present disclosure, when the temperature of the low-temperature side heat medium flowing into the chiller drops, it is possible to suppress a decrease in heating capacity while preventing the refrigerant flowing into the compressor of the refrigeration cycle from becoming liquid phase or a gas-liquid mixed phase state. [Brief description of the drawings]

[0012] [Figure 1] 1 is a diagram showing a schematic configuration of a thermal management device for a vehicle according to an embodiment of the present disclosure; [Diagram 2] 4 is a flowchart showing an example of a process for controlling an electric heater, which is executed by an ECU. [Diagram 3] FIG. 11 is a diagram showing a schematic configuration of a heat management device for a vehicle according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure will now be described in detail with reference to the accompanying drawings, in which the same or corresponding parts are designated by the same reference characters and will not be described repeatedly.

[0014] <Embodiment 1> Fig. 1 is a diagram showing a schematic configuration of a thermal management device for a vehicle according to this embodiment. As shown in Fig. 1, vehicle 1 is an electric vehicle (xEV) equipped with a thermal management device 10 according to this embodiment. Vehicle 1 is a BEV (electric vehicle). However, vehicle 1 may be, for example, an industrial vehicle or another electric vehicle such as a plug-in hybrid vehicle.

[0015] The thermal management device 10 includes a thermal management circuit 100 and an ECU (Electronic Control Unit) 500. The ECU 500 includes a processor 501 and a memory 502. The processor 501 executes a program stored in the memory 502, whereby various types of thermal management control in the ECU 500 are performed.

[0016] The thermal management device 10 is configured to perform thermal management of the vehicle 1 using the heat medium of the thermal management circuit 100. The thermal management circuit 100 includes a first circuit 110, a second circuit 120, and a third circuit 130. The thermal management circuit 100 also includes a condenser 140, a refrigeration cycle 150, a chiller 160, a five-way valve 310, and a reservoir tank (R / T) 320. The five-way valve 310 and the reservoir tank 320 are shared by the second circuit 120 and the third circuit 130. The condenser 140, the refrigeration cycle 150, and the chiller 160 are disposed between the first circuit 110 and the second circuit 120. The second circuit 120, the third circuit 130, and a flow path 170a described later correspond to an example of a "low-temperature side circuit" according to the present disclosure, and are also referred to as the low-temperature side circuit hereinafter.

[0017] The first circuit 110 includes a first flow path through which the high-temperature side heat medium flows. The first circuit 110 includes a pump 111, an electric heater 112, a three-way valve 113, a heater core 114, a reservoir tank (R / T) 115, and a high-temperature radiator 118. The three-way valve 113 switches the path of the high-temperature side heat medium. The pump 111 circulates the high-temperature side heat medium through the first circuit 110. The high-temperature side heat medium exchanges heat with each device when passing through. The heater core 114 is used as a heating source (heat source) for the air conditioner 2.

[0018] The five-way valve 310 switches the path of the low-temperature side heat medium. The five-way valve 310 has five ports P1 to P5. The ECU 500 controls the five-way valve 310 to assume one of the first to fifth connection patterns. Hereinafter, the ports P1, P2, P3, P4, and P5 may be simply referred to as "P1", "P2", "P3", "P4", and "P5", respectively.

[0019] In the first connection pattern, P1 and P2 are connected, P3 and P4 are connected, and P5 is in an unconnected state. In the second connection pattern, P1 and P2 are connected, P4 and P5 are connected, and P3 is in an unconnected state. In the third connection pattern, P1 and P5 are connected, P3 and P4 are connected, and P2 is in an unconnected state. In the fourth connection pattern, P2 and P4 are connected, P1 and P3 are connected, and P5 is in an unconnected state. In the fifth connection pattern, P2 and P4 are connected, P1 and P5 are connected, and P3 is in an unconnected state.

[0020] Flow paths 120a and 120b are connected to ports P1 and P2 of the five-way valve 310, respectively. Flow path 120a is a flow path that connects port P1 and reservoir tank 320. Flow path 120b is a flow path that connects port P2 and reservoir tank 320. By connecting P1 and P2 of the five-way valve 310 (for example, first and second connection patterns), a second circuit 120 including the flow paths 120a and 120b is formed.

[0021] A pump 121 and a chiller 160 are arranged in the flow path 120a. A battery 200 and an electric battery heater 220 are arranged in the flow path 120b. The pump 121 circulates the low-temperature side heat medium through the second circuit 120. The low-temperature side heat medium exchanges heat with each device when passing through. For this reason, each device is equipped with a heat exchanger (or has the function of a heat exchanger). The battery 200 corresponds to an example of a "battery" in this disclosure.

[0022] Flow paths 130b and 130a are respectively connected to ports P3 and P4 of the five-way valve 310. The flow paths 130b and 130a are flow paths that connect ports P3 and P4 to the reservoir tank 320. By connecting P3 and P4 of the five-way valve 310 (for example, the first and third connection patterns), a third circuit 130 including the flow paths 130a and 130b is formed.

[0023] The high-temperature heat medium may be a known heat medium for heating, and the low-temperature heat medium may be insulating oil or antifreeze. In addition, in the refrigeration cycle 150 described later, the refrigerant may be hydrofluorocarbon (HFC), ammonia, carbon dioxide, or the like.

[0024] In the flow path 130a, a pump 131, an SPU (Smart Power Unit) 132, a motor PCU (Power Control Unit) 133, and an oil cooler (O / C) 135 are arranged. The oil cooler 135 cools the trunk axle of the vehicle 1. The pump 131 circulates the low-temperature side heat medium in the third circuit 130. The low-temperature side heat medium exchanges heat with each device when passing through. For this reason, each device is equipped with a heat exchanger (or has the function of a heat exchanger). The motor PCU 133 and the oil cooler 135 correspond to an example of a "vehicle drive device" in this disclosure.

[0025] A flow path 170a is connected to a port P5 of the five-way valve 310. The flow path 170a connects the port P5 and the reservoir tank 320. A low-temperature radiator 170 is provided in the flow path 170a. The low-temperature radiator 170 functions as a heat exchanger. The low-temperature radiator 170 exchanges heat between the low-temperature side refrigerant flowing through the flow path 170a and the outside air.

[0026] A refrigerant circulates through the refrigeration cycle 150. The refrigeration cycle 150 includes a compressor 151, an electric expansion valve 152, an evaporator 153, an evaporative pressure regulator (EPR) 154, and an electric expansion valve 155. The compressor 151 compresses and discharges the refrigerant flowing out of the chiller 180. The evaporator 153 is used as a cooling source for the air conditioner 2. The condenser 140 is connected to both the first circuit 110 and the refrigeration cycle 150, and functions as a heat exchanger. The condenser 140 exchanges heat between the high-temperature side heat medium flowing through the first circuit 110 and the refrigerant circulating through the refrigeration cycle 150. The chiller 160 is connected to both the refrigeration cycle 150 and the flow path 120a, and functions as a heat exchanger. The chiller 160 exchanges heat between the refrigerant circulating in the refrigeration cycle 150 and the low-temperature side heat medium flowing in the second circuit 120. In this manner, the condenser 140, the refrigeration cycle 150, and the chiller 160 are configured to transfer heat between the high-temperature side heat medium flowing in the first circuit 110 and the low-temperature side heat medium flowing in the second circuit 120.

[0027] The air conditioner 2 performs heating by utilizing the heat dissipated by the condenser 140. When the air conditioner 2 performs heating, the three-way valve 113 has ports Pa and Pb connected, and the high-temperature side heat medium that absorbs heat in the condenser 140 dissipates heat in the heater core 114, thereby performing heating. When the five-way valve 310 is set to, for example, the second connection pattern during heating, and the battery 200 is cooled in the low-temperature side circuit, the heat (waste heat) of the battery 200 absorbed by the low-temperature side refrigerant is absorbed by the refrigerant of the refrigeration cycle 150 in the chiller 160, and the heat of the battery 200 is absorbed by the high-temperature side heat medium in the condenser 140, so that the heat (waste heat) of the battery 200 is used for heating.

[0028] When the low-temperature side circuit is switched to stop cooling the battery 200 and the five-way valve 310 is set to the third connection pattern, for example, the low-temperature side refrigerant cannot exchange heat with the battery 200, and therefore the heat (waste heat) of the battery 200 cannot be used for heating. In this case, when the temperature of the low-temperature side refrigerant is lower than the outside air, the low-temperature side refrigerant absorbs the heat of the outside air in the low-temperature radiator 170. The low-temperature side refrigerant also absorbs the heat of the motor PCU 133 and the oil cooler 135, and these heats are absorbed by the refrigerant of the refrigeration cycle 150 in the chiller 160, so that the heat of the outside air, the motor PCU 133, and the oil cooler 135 is used for heating. However, since the heat of the battery 200 is not absorbed by the low-temperature side refrigerant flowing into the chiller 160, the temperature of the refrigerant flowing out of the chiller 160 decreases, and the refrigerant flowing into the compressor 151 may become liquid phase or gas-liquid mixed phase. In the above-mentioned Patent Document 1, when cooling of battery 200 by the low-temperature side circuit is stopped, the rotation speed of compressor 151 is reduced to suppress the occurrence of liquid backflow, in which liquid-phase refrigerant flows into compressor 151. However, this reduces the amount of refrigerant flowing into chiller 160, thereby reducing heating capacity.

[0029] In this embodiment, an electric heater 300 that heats the refrigerant flowing out of the chiller 160 and flowing into the compressor 151 is provided in the refrigeration cycle 150, thereby preventing the refrigerant flowing into the compressor 151 from becoming liquid phase or gas-liquid mixed phase.

[0030] 2 is a flowchart showing an example of the process of electric heater control executed by the ECU 500. This flowchart is executed, for example, when the five-way valve 310 is switched from the first connection pattern to the third connection pattern during heating of the air conditioner 2. First, in step (hereinafter, step is abbreviated as "S") 10, a temperature difference ΔT of the low-temperature side heat medium flowing into the chiller 160 before and after the low-temperature side circuit is switched is calculated. The temperature of the low-temperature side heat medium flowing into the chiller 160 may be detected by the temperature sensor 12 provided in the second circuit 120. The temperature detected by the temperature sensor 12 immediately before switching from the first connection pattern to the third connection pattern is stored as Tb in the memory 502. The current temperature (temperature after switching to the third connection pattern) Tr is detected by the temperature sensor 12. Then, the temperature difference ΔT=Tb-Tr is calculated.

[0031] In the next S11, it is determined whether the temperature difference ΔT is equal to or greater than a predetermined value α. The predetermined value α is set in advance by experiment or the like, and is a value at which it is estimated that the refrigerant flowing into compressor 151 will be in liquid phase or gas-liquid mixed phase due to a lack of heat (lack of temperature) in the low-temperature side heat medium flowing through chiller 160. If the temperature difference ΔT is the predetermined value α, a positive determination is made and the process proceeds to S12. If the temperature difference ΔT is less than the predetermined value α, a negative determination is made and the process proceeds to S13.

[0032] In S12, electricity is supplied to the electric heater 300 provided in the refrigeration cycle 150 to heat the refrigerant flowing out of the chiller 160 and flowing into the compressor 151. The amount of electricity (power) supplied to the electric heater 300 may be a predetermined value, or a heat deficit in the chiller 160 may be calculated based on the temperature difference ΔT, and a value according to the heat deficit may be set.

[0033] In the next S14, it is determined whether or not the recovery condition is satisfied. The recovery condition may be when a set time has elapsed since the start of energization of the electric heater 300, when the temperature difference ΔT becomes equal to or smaller than a predetermined value β (β<α), or when the current temperature Tr exceeds a set temperature. If the recovery condition is not satisfied, the process returns to S12 and energization of the electric heater 300 continues. If the recovery condition is satisfied, the process proceeds to S15, where energization of the electric heater 300 is stopped, and the current process is terminated.

[0034] In S13, it is determined whether or not a predetermined time A has elapsed since the low-temperature side circuit was switched (since the first connection pattern was switched to the third connection pattern). The predetermined time A is intended to compensate for the delay until the temperature of the low-temperature side heat medium changes after the low-temperature side circuit is switched. If the predetermined time A has not elapsed, a negative determination is made and the process returns to S10. If the predetermined time A has elapsed, a positive determination is made and the current process is terminated.

[0035] According to this embodiment, when the air conditioner 2 is heating, the low-temperature side circuit is switched and the heat exchanger that absorbs heat into the low-temperature side heat medium is switched from the battery 200 to the motor PCU 133, the oil cooler 135, and the low-temperature radiator 170. If the temperature Tr of the low-temperature side heat medium flowing into the chiller 160 after the switching is lower than the temperature Tb of the low-temperature refrigerant flowing into the chiller 160 before the switching by a predetermined value α or more, the electric heater 300 that heats the refrigerant that flows out of the chiller 160 and into the compressor 151 is energized. This makes it possible to compensate for the decrease in the amount of heat absorbed by the refrigerant and to prevent the refrigerant flowing into the compressor 151 from becoming liquid phase or gas-liquid mixed phase. Also, it is possible to increase the rotation speed of the compressor 151 as necessary to maintain the amount of refrigerant required for heating, and to prevent a decrease in the heating capacity.

[0036] <Embodiment 2> 3 is a diagram showing a schematic configuration of a thermal management device for a vehicle according to the second embodiment. In the second embodiment, the thermal management device 10 is configured by replacing the electric heater 300 of the first embodiment with a bypass passage 150p. A thermal management circuit 100a according to the second embodiment includes a bypass passage 150p that bypasses the discharge side and the inlet side of a compressor 151 in a refrigeration cycle 150. A flow control valve 400 is provided in the bypass passage 150p. The other configurations of the thermal management circuit 100a are similar to those of the thermal management circuit 100.

[0037] In the second embodiment, the opening and closing control of the flow control valve 400 is executed by replacing S12 with "open the flow control valve 400" and S15 with "close the flow control valve" in the flowchart of Fig. 2. Note that in S12, the opening degree of the flow control valve 400 may be a predetermined value, and the heat deficit in the chiller 160 may be calculated based on the temperature difference ΔT and set to a value according to the heat deficit.

[0038] According to this embodiment, when the low-temperature side circuit is switched during heating by the air conditioner 2, and the heat exchanger that absorbs heat into the low-temperature side heat medium is switched from the battery 200 to the motor PCU 133, the oil cooler 135, and the low-temperature radiator 170, if the temperature of the low-temperature side heat medium flowing into the chiller 160 after the switching is lower than the temperature of the low-temperature refrigerant flowing into the chiller 160 before the switching by a predetermined value α or more, the flow control valve 400 opens, and the refrigerant is returned to the compressor 151 using the bypass passage 150p that allows the refrigerant discharged from the compressor 151 to flow into the compressor 151. Since the returned refrigerant is in a state of superheated vapor, it is possible to compensate for the decrease in the amount of heat absorbed by the refrigerant flowing into the compressor 151, and it is possible to suppress the refrigerant flowing into the compressor 151 from becoming a liquid phase or a gas-liquid mixed phase. In addition, it is possible to increase the rotation speed of the compressor 151 as necessary to maintain the amount of refrigerant required for heating, and it is possible to suppress a decrease in the heating capacity.

[0039] In the above embodiment, electric heater 300 or bypass passage 150p (flow control valve 400) is controlled based on the temperature difference ΔT of the low-temperature side circuit. However, the temperature difference of the low-temperature side heat medium when switching the low-temperature side circuit may be obtained from the temperature of the low-temperature side heat medium in chiller 160 and the temperature of the low-temperature side heat medium in low-temperature radiator 170.

[0040] In the above embodiment, when the low-temperature side circuit is switched from the first connection pattern to the third connection pattern, the flowchart in Fig. 2 is executed. However, even when the low-temperature side circuit is switched from the first connection pattern to the third connection pattern, the flowchart in Fig. 2 may be executed when the temperature of the low-temperature side heat medium flowing into chiller 160 becomes lower by a predetermined value or more than the temperature of the low-temperature side heat medium flowing into chiller 160 before the switch due to switching of the low-temperature side circuit.

[0041] In the above embodiment, the first circuit 110 is provided with the heater 112, but the heater 112 may be omitted. The condenser 140 may be used as the heating source for the air conditioner 2. In this case, the heater 112, the three-way valve 113, and the heater core 114 of the first circuit 110 may be omitted.

[0042] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not by the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0043] 1 vehicle, 2 air conditioning device, 100 thermal management circuit, 110 first circuit, 120 second circuit (low temperature side circuit), 130 third circuit (low temperature side circuit), 140 condenser, 150 refrigeration cycle, 150p bypass passage, 160 chiller, 170 low temperature radiator, 200 battery, 300 electric heater, 400 flow control valve, 500 ECU.

Claims

[Claim 1] a refrigeration cycle including a compressor that compresses and discharges a refrigerant flowing out of a chiller, a condenser that dissipates heat from the refrigerant discharged from the compressor, and a pressure reducing unit that reduces the pressure of the refrigerant flowing out of the condenser, wherein the chiller exchanges heat between the refrigerant decompressed in the pressure reducing unit and a low-temperature side heat medium; a low-temperature side circuit having a heat exchanger that absorbs heat from a battery, heat from a vehicle drive device, and heat from outside air into the low-temperature side heat medium; and an air conditioning device that performs heating by utilizing heat dissipated by the condenser. an electric heater for heating the refrigerant flowing out of the chiller and into the compressor; or, a bypass passage for allowing the refrigerant discharged from the compressor to flow into the compressor, a heat management device for a vehicle, wherein, during heating by the air conditioning device, when the heat exchanger in the low-temperature side circuit, which causes the low-temperature side heat medium to absorb heat, is switched, if the temperature of the low-temperature side heat medium flowing into the chiller after the heat exchanger is switched is lower by a predetermined value or more than the temperature of the low-temperature side heat medium flowing into the chiller before the switching, the electric heater is energized or the refrigerant is circulated through the bypass passage.

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