Heat management device for vehicle

Abstract

To prevent a refrigerant flowing into a compressor of a refrigerant circuit from becoming a liquid phase state or a gas-liquid mixed phase state even when a response delay of an expansion valve occurs.SOLUTION: When switching from a first mode (a circuit A) in which there is a heating request for an air conditioner and there is a cooling request for a battery 200 to a second mode (a circuit B) in which there is the heating request for the air conditioner and there is no cooling request for the battery 200, an opening of an electric expansion valve 155 of a refrigerant circuit 150 is reduced for a predetermined period. After a lapse of the predetermined period, the first mode (the circuit A) is switched to the second mode (the circuit B).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a vehicle thermal management device.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2020-165604 (Patent Document 1) discloses a refrigerant circuit device applied to an air conditioner of an electric vehicle. In this refrigerant circuit device, heat from a battery (battery) or outside air, which is absorbed by a chiller disposed in a refrigerant circuit (heat pump cycle), is used for heating the vehicle interior. Heat from the battery or outside air is absorbed by the chiller through a low-temperature side heat medium circuit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The refrigerant circuit device of Patent Document 1 includes a heating mode and a cooling and heating mode. The heating mode heats the vehicle interior without cooling the battery. In the cooling and heating mode, heat absorbed during battery cooling is used for heating the vehicle interior. Therefore, when switching from the cooling and heating mode to the heating mode, since heat absorption from the battery stops, the temperature of the low-temperature side heat medium flowing into the chiller decreases, and the refrigerant flowing into the compressor of the refrigerant circuit becomes in a liquid phase or a gas-liquid mixed phase state, causing problems in the compressor. In Patent Document 1, when cooling of the battery by the low-temperature side heat medium circuit (low-temperature side circuit) is stopped, the rotation speed of the compressor is decreased, or the opening degree of an expansion valve that decompresses the refrigerant flowing into the chiller is decreased, thereby reducing the flow rate of the refrigerant flowing into the chiller and suppressing the occurrence of liquid back where liquid-phase refrigerant flows into the compressor.

[0005] When reducing the opening degree of the expansion valve, a response delay may occur. In this case, the flow rate of the refrigerant flowing into the chiller may temporarily become excessive, and there is a concern that the occurrence of liquid backflow in which the liquid-phase refrigerant flows into the compressor cannot be suppressed.

[0006] An object of the present disclosure is to suppress the refrigerant flowing into the compressor of the refrigerant circuit from becoming in a liquid phase or a gas-liquid mixed phase even when a response delay of the expansion valve occurs.

Means for Solving the Problems

[0007] The vehicle thermal management device according to the present disclosure includes a compressor that compresses and discharges the refrigerant flowing out of the chiller, a condenser that radiates the heat of the refrigerant discharged from the compressor, and an expansion valve that decompresses the refrigerant flowing out of the condenser. The chiller has a refrigerant circuit that exchanges heat between the refrigerant decompressed by the expansion valve and the low-temperature side heat medium, and a low-temperature side circuit that has heat exchange equipment that absorbs the heat of the battery, the heat of the vehicle drive device, and the heat of the outside air in the low-temperature side heat medium, an air conditioner that performs heating using the heat radiation of the condenser, and a control device. The control device controls the opening degree of the expansion valve to a predetermined opening degree when there is a heating demand and a cooling demand for the battery in the first state, and the refrigerant exchanges heat with the low-temperature side heat medium that has absorbed the heat of the battery in the chiller to perform battery cooling and heating. When switching from the first state to the second state where there is a heating demand and no cooling demand, the opening degree of the expansion valve is made smaller than the predetermined opening degree for a predetermined period, and then switched from the first state to the second state. In the second state, the low-temperature side heat medium does not flow through the battery heat exchanger.

[0008] According to this configuration, the refrigerant in the refrigerant circuit absorbs heat from the low-temperature side 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, radiates heat in the condenser, and is used for heating. Thereby, the heat of the battery, the heat of the vehicle drive device, and the heat of the outside air are used for heating.

[0009] When the control device is in the first state where there is a heating demand and a battery cooling demand, it controls the opening degree of the expansion valve to a predetermined opening degree so that the refrigerant exchanges heat with the low-temperature side heat medium that has absorbed the heat of the battery in the chiller, thereby cooling the battery and heating the air conditioner. In the second state where there is a heating demand but no cooling demand, since the low-temperature side heat medium does not flow through the heat exchanger of the battery, the heat of the battery is not used for heating. When switching from the first state to the second state, the control device reduces the opening degree of the expansion valve to be smaller than the predetermined opening degree for a predetermined period, and then switches from the first state to the second state.

[0010] In the first state, since the battery is cooled, the heat of the battery is absorbed by the low-temperature side heat medium. However, in the second state, since the battery is not cooled, the heat of the battery is not absorbed by the low-temperature side heat medium. Therefore, when switching from the first state to the second state, the temperature of the low-temperature side heat medium flowing into the chiller decreases. At this time, even if the opening degree of the expansion valve is decreased to reduce the flow rate of the refrigerant flowing into the chiller, due to the response delay of the change in the opening degree of the expansion valve, the flow rate of the refrigerant temporarily becomes excessive, and there is a concern that liquid backflow may occur where the liquid-phase refrigerant flows into the compressor.

[0011] According to this configuration, when switching from the first state to the second state, the opening degree of the expansion valve is made smaller than the predetermined opening degree for a predetermined period, and then switched from the first state to the second state. During the predetermined period when the opening degree of the expansion valve is small, the flow rate of the refrigerant flowing into the chiller decreases and the dryness (quality) of the refrigerant increases, so the occurrence of liquid backflow when switching from the first state to the second state can be suppressed.

[0012] Preferably, in the second state, the refrigerant may perform heat exchange with the low-temperature side heat medium that has absorbed the heat of at least one of the vehicle drive device and the outside air in the chiller to perform heating.

[0013] According to this configuration, in the second state, heating of the air conditioner can be performed using the heat of at least one of the vehicle drive device and the outside air.

[0014] Preferably, when the control device switches from the first state to the second state, if it is predicted that the temperature of the low-temperature side heat medium flowing into the chiller will drop below a predetermined temperature, the opening degree of the expansion valve may be made smaller than a predetermined opening degree for a predetermined period.

[0015] When switching from the first state to the second state, if it is predicted that the temperature of the low-temperature side heat medium flowing into the chiller is less than a predetermined temperature, there is a high possibility that liquid back will not occur. According to this configuration, when switching from the first state to the second state, if it is predicted that the temperature of the low-temperature side heat medium flowing into the chiller will drop by a predetermined temperature or more, the opening degree of the expansion valve is made smaller than a predetermined opening degree for a predetermined period. And when there is a high possibility that liquid back will not occur, the flow rate of the refrigerant flowing into the chiller is not reduced, so that a decrease in heating performance can be minimized.

[0016] Preferably, the control device controls the opening degree of the expansion valve so that the superheat degree of the refrigerant flowing out of the chiller becomes a target value, and by increasing and correcting the target value for a predetermined period, the opening degree of the expansion valve may be made smaller than a predetermined opening degree.

[0017] According to this configuration, the opening degree of the expansion valve is controlled so that the superheat degree of the refrigerant flowing out of the chiller becomes a target value, and by increasing and correcting the target value for a predetermined period, the opening degree of the expansion valve is made smaller than a predetermined opening degree. Therefore, for example, the superheat degree of the refrigerant flowing into the compressor can be maintained at 1 or more, and liquid back can be suppressed.

[0018] Preferably, in the above configuration, the control device may be configured to increase the rotational speed of the compressor for a predetermined period.

[0019] According to this configuration, since the rotational speed of the compressor is increased for a predetermined period, the decrease in the flow rate of the refrigerant can be suppressed while making the superheat degree of the refrigerant flowing out of the chiller a target value, and the decrease in heating performance before switching from the first state to the second state can be minimized.

Advantages of the Invention

[0020] According to the present disclosure, even when a response delay of the expansion valve occurs, it is possible to suppress the refrigerant flowing into the compressor of the refrigerant circuit from becoming a liquid phase or a gas-liquid mixed phase.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0022] Embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

[0023] FIG. 1 is a diagram showing a schematic configuration of a vehicle thermal management device according to this embodiment. As shown in FIG. 1, the vehicle 1 is an electric vehicle (xEV) equipped with the thermal management device 10 according to this embodiment. The vehicle 1 is a BEV (battery electric vehicle). However, the vehicle 1 may be, for example, an industrial vehicle or another electric vehicle such as a plug-in hybrid vehicle.

[0024] 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. By the processor 501 executing the program stored in the memory 502, various thermal management controls in the ECU 500 are executed. The ECU 500 corresponds to an example of the "control device" of the present disclosure.

[0025] The heat management device 10 is configured to perform heat management of the vehicle 1 using the heat medium of the heat management circuit 100. The heat management circuit 100 includes a first circuit 110, a second circuit 120, and a third circuit 130. Further, the heat management circuit 100 includes a capacitor 140, a refrigerant circuit 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. Further, the capacitor 140, the refrigerant circuit 150, and the chiller 160 are arranged 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 the "low-temperature side circuit" according to the present disclosure, and are hereinafter also referred to as the low-temperature side circuit.

[0026] The first circuit 110 includes a first flow path through which a high-temperature side heat medium flows. The first circuit 110 includes a pump 111, an electric heater 112 for heating, 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 heat source of the heating source of the air conditioner 2.

[0027] The five-way valve 310 switches the path of the low-temperature side heat medium. The five-way valve 310 includes five ports P1 to P5. The ECU 500 controls the five-way valve 310 so as to be in any 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.

[0028] In the first connection pattern, P1 and P2 are connected, P3 and P4 are connected, and P5 is in a non-connected state. In the second connection pattern, P1 and P2 are connected, P4 and P5 are connected, and P3 is in a non-connected state. In the third connection pattern, P1 and P5 are connected, P3 and P4 are connected, and P2 is in a non-connected state. In the fourth connection pattern, P2 and P4 are connected, P1 and P3 are connected, and P5 is in a non-connected state. In the fifth connection pattern, P2 and P4 are connected, P1 and P5 are connected, and P3 is in a non-connected state.

[0029] Flow paths 120a and 120b are respectively connected to ports P1 and P2 of the five-way valve 310. Flow path 120a is a flow path connecting port P1 and the reservoir tank 320. Flow path 120b is a flow path connecting port P2 and the reservoir tank 320. When P1 and P2 of the five-way valve 310 are connected (for example, in the first and second connection patterns), the second circuit 120 including flow paths 120a and 120b is formed.

[0030] A pump 121 and a chiller 160 are arranged in flow path 120a. A battery 200 and an electric battery heater 220 are arranged in 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. Therefore, each device is provided with a heat exchanger (or has the function of a heat exchanger). The battery 200 corresponds to an example of the "battery" in the present disclosure.

[0031] Flow paths 130b and 130a are respectively connected to ports P3 and P4 of the five-way valve 310. Flow paths 130b and 130a are flow paths connecting ports P3 and P4 and the reservoir tank 320, respectively. When P3 and P4 of the five-way valve 310 are connected (for example, in the first and third connection patterns), the third circuit 130 including flow paths 130a and 130b is formed.

[0032] The high-temperature-side heat medium may be a known heat medium for heating, and the low-temperature-side heat medium may be insulating oil or antifreeze. Also, in the refrigerant circuit 150 described later, refrigerants such as hydrofluorocarbons (HFCs), ammonia, and carbon dioxide may be used.

[0033] In the flow path 130a, a pump 131, an SPU (Signal Processing Unit) 132, a PCU (Power Control Unit) 133 for a motor, 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 through the third circuit 130. The low-temperature-side heat medium exchanges heat with each device when passing through. For this reason, each device includes (or has the function of) a heat exchanger. The PCU 133 for the motor and the oil cooler 135 correspond to an example of the "vehicle drive device" of the present disclosure.

[0034] A flow path 170a is connected to the port P5 of the five-way valve 310. The flow path 170a is a flow path connecting 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. Heat exchange occurs between the low-temperature-side heat medium flowing through the flow path 170a and the outside air by the low-temperature radiator 170.

[0035] Refrigerant circulates in the refrigerant circuit 150. The refrigerant circuit 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 from the chiller 160. The refrigerant circuit 150 is a refrigeration cycle or a heat pump cycle. The electric expansion valve 155 corresponds to the "expansion valve" of the present disclosure.

[0036] The evaporator 153 is used as a cooling source of the air conditioner 2. The condenser 140 is connected to both the first circuit 110 and the refrigerant circuit 150 and functions as a heat exchanger. By the condenser 140, the high-temperature side heat medium flowing through the first circuit 110 and the refrigerant circulating in the refrigerant circuit 150 exchange heat. The chiller 160 is connected to both the refrigerant circuit 150 and the flow path 120a and functions as a heat exchanger. By the chiller 160, the refrigerant circulating in the refrigerant circuit 150 and the low-temperature side heat medium flowing through the second circuit 120 exchange heat. Thus, the condenser 140, the refrigerant circuit 150, and the chiller 160 are configured to perform heat transfer between the high-temperature side heat medium flowing through the first circuit 110 and the low-temperature side heat medium flowing through the second circuit 120.

[0037] The air conditioner 2 performs heating in the vehicle interior by utilizing the heat dissipation of the condenser 140. During heating of the air conditioner 2, the three-way valve 113 connects the ports Pa and Pb, and the high-temperature side heat medium that has absorbed heat in the condenser 140 dissipates heat in the heater core 114, thereby performing heating. During heating, the five-way valve 310 is set to, for example, the second connection pattern (P1 and P2, P4 and P5 are connected). When the battery 200 is being cooled in the low-temperature side circuit, the heat (waste heat) of the battery 200 absorbed by the low-temperature side heat medium is absorbed by the refrigerant in the refrigerant circuit 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. Therefore, the heat (waste heat) of the battery 200 is utilized for heating. Thus, the mode of simultaneously executing heating and cooling of the battery 200 is referred to as the first mode. The first mode corresponds to an example of the "first state" of the present disclosure.

[0038] When the air conditioner 2 is in heating operation and there is no cooling demand from the battery 200, the cooling of the battery 200 is stopped. As a result, the low-temperature side circuit is switched. For example, when the five-way valve 310 is set to the third connection pattern (P1 and P5, P3 and P4 are connected), the low-temperature side heat medium cannot exchange heat with the battery 200, so the heat (waste heat) of the battery 200 cannot be utilized for heating. In this case, when the temperature of the low-temperature side heat medium is lower than the outside air, the low-temperature side heat medium absorbs the heat of the outside air in the low-temperature radiator 170. Also, the low-temperature side heat medium absorbs the heat of the motor PCU 133 and the oil cooler 135, and this heat is absorbed by the refrigerant in the refrigerant circuit 150 in the chiller 160. Therefore, the heat of the outside air, the motor PCU 133, and the oil cooler 135 is utilized for heating. In this way, the mode of performing heating without cooling the battery 200 is referred to as the second mode. The second mode corresponds to an example of the "second state" of the present disclosure.

[0039] FIG. 2 is a diagram showing the heat flow during heating operation of the air conditioner 2. FIG. 2(A) shows the heat flow during heating in the first mode, and in the present embodiment, the state of this heat management circuit 100 is also referred to as circuit A. FIG. 2(B) shows the heat flow during heating in the second mode, and in the present embodiment, the state of this heat management circuit 100 is also referred to as circuit B. In the first mode, as shown in FIG. 2(A), the heat (waste heat) of the battery 200 absorbed by the low-temperature side heat medium is absorbed by the refrigerant in the refrigerant circuit 150 in the chiller 160, and the heat of the battery 200 is absorbed by the high-temperature side heat medium in the capacitor 140 and radiated from the heater core 114. Therefore, the heat (waste heat) of the battery 200 is utilized for heating. In the second mode, as shown in FIG. 2(B), the heat of the outside air, the motor PCU 133, and the oil cooler 135 is radiated from the heater core 114 and utilized for heating.

[0040] When the battery 200 is cooled, since the amount of heat generated by the battery 200 is large (the temperature of the battery 200 is high), in the first mode (circuit A), the amount of heat absorbed by the low-temperature side heat medium flowing into the chiller 160 is large. In the second mode (circuit B), the amount of heat absorbed by the low-temperature side heat medium from the outside air, the motor PCU 133, and the oil cooler 135 is less than that in the first mode.

[0041] Figure 3 is a diagram showing the transition of various parameters when switching from the first mode (circuit A) to the second mode (circuit B). Figure 3(A) shows the transition of various parameters in the comparative example, and Figure 3(B) shows the transition of various parameters in the present embodiment. In Figures 3(A) and (B), from the top, the chiller 160 inlet temperature of the low-temperature side heat medium (chiller inlet temperature Ti), the superheat degree target value (SH target value) after the chiller 160 of the refrigerant (refrigerant circuit 150), the opening degree of the electronic expansion valve 155 (expansion valve opening degree K), the dryness (quality) of the refrigerant after the chiller 160, the rotational speed of the compressor 151, the heating performance of the air conditioner 2, and the refrigerant flow rate Q flowing into the chiller 160 are shown.

[0042] In the comparative example, as shown in Figure 3(A), at time t1, the switching from the first mode (circuit A) to the second mode (circuit B) is performed. When switching from circuit A to circuit B, the chiller inlet temperature Ti drops rapidly. Since the superheat degree target value (SH target value) after the chiller 160 does not change, in order to make the superheat degree of the refrigerant the SH target value, the expansion valve opening degree K decreases. At this time, due to the responsiveness of the change in the opening degree of the electronic expansion valve 155, the refrigerant flow rate Q becomes temporarily excessive with respect to the decrease in the chiller inlet temperature Ti (refer to the portion surrounded by the dashed-dotted line). For this reason, the refrigerant cannot absorb heat sufficiently, and the refrigerant flowing into the compressor 151 becomes in a liquid phase or a gas-liquid mixed phase state, resulting in liquid back.

[0043] In the present embodiment shown in FIG. 3(B), from the time t0, which is a time predetermined time ts before the time t1 when switching from circuit A to circuit B, the SH target value is increased and corrected to increase the SH target value. The predetermined time ts corresponds to the "predetermined period" of the present disclosure. When the increase in the SH target value starts at time t0, the expansion valve opening degree K decreases. As a result, the refrigerant flow rate Q decreases, and the dryness (quality) of the refrigerant increases. At time t1, when switching from circuit A to circuit B, the increase correction of the SH target value is stopped, and the SH target value is returned to the normal value. As a result, the chiller inlet temperature Ti drops rapidly and the expansion valve opening degree K decreases. Since the refrigerant flow rate Q decreases and the dryness of the refrigerant is increasing, at time t1, even if the chiller inlet temperature Ti drops rapidly and the expansion valve opening degree K decreases, the refrigerant does not enter the liquid phase or the gas-liquid mixed phase state, and liquid back can be suppressed.

[0044] In the present embodiment, at time t0, the rotational speed of the compressor 151 is increased, and at time t1, the rotational speed of the compressor 151 is returned to the normal value. When the expansion valve opening degree K decreases at time t0, as shown by the dashed-dotted line in FIG. 3(B), the refrigerant flow rate Q decreases, and the heating performance deteriorates. By increasing the rotational speed of the compressor 151 at time t0, as shown by the solid line, the decrease in the refrigerant flow rate Q can be suppressed, and the deterioration of the heating performance can also be suppressed.

[0045] FIG. 4 is a flowchart showing an example of the process of control during circuit switching, which is executed by the ECU 500. This flowchart is repeatedly executed at predetermined intervals when the power switch (ignition switch) of the vehicle 1 is in the ON state. In step (hereinafter, steps are abbreviated as "S") 10, it is determined whether there is a switching request from the first mode (circuit A) to the second mode (circuit B). The first mode is when there is a heating request for the air conditioner 2 and a cooling request for the battery 200. For example, the five-way valve 310 is set to the second connection pattern to perform heating in the vehicle interior and cooling of the battery 200. Then, when the battery 200 is cooled (the temperature of the battery 200 decreases), the cooling request disappears, and the heating request continues, a switching request is generated to switch from the first mode to the second mode. The second mode is when there is a heating request for the air conditioner 2 and no cooling request for the battery 200. For example, the five-way valve 310 is set to the third connection pattern, and the heat of the outside air, the motor PCU 133, and the oil cooler 135 is used for heating without cooling the battery 200.

[0046] If there is no switching request from the first mode (circuit A) to the second mode (circuit B), a negative determination is made in S10, and the current routine ends. If there is a switching request from the first mode (circuit A) to the second mode (circuit B), an affirmative determination is made and the process proceeds to S11.

[0047] In S11, when switching from circuit A to circuit B, it is determined whether the chiller inlet temperature Ti drops by a predetermined temperature S or more. For example, when the first mode (circuit A) is set (the state before switching from circuit A to circuit B), the estimated temperature drop ΔTi is calculated by subtracting the low-temperature side heat medium temperature To detected by the temperature sensor 13 provided at the outlet of the oil cooler 135 in the flow path 130a from the temperature (chiller inlet temperature Ti) of the low-temperature side heat medium detected by the temperature sensor 12 provided at the inlet of the chiller 160 of the second circuit 120 (ΔTi = Ti - To). When the estimated temperature drop ΔTi is equal to or higher than the predetermined temperature S (ΔTi ≧ S), it is determined that the chiller inlet temperature Ti drops by a predetermined temperature S or more, and the process proceeds to S12. When the estimated temperature drop ΔTi is less than the predetermined temperature S (ΔTi < S), a negative determination is made, and the process proceeds to S17, and after switching from circuit A to circuit B, this routine ends.

[0048] In S12, the target SH (the target value of the superheat degree after the chiller 160 of the refrigerant) is increased. The increase in the target SH may be increased and corrected so that the target SH gradually increases, or the target SH may be increased step by step. When the target SH increases, the expansion valve opening degree K of the electric expansion valve 155 decreases. As a result, the refrigerant flow rate Q flowing into the chiller 160 decreases, and the dryness (quality) of the refrigerant after the chiller 160 increases. Therefore, in S15 described later, even when the chiller inlet temperature Ti drops rapidly and the expansion valve opening degree K decreases when switching from circuit A to circuit B, the refrigerant does not become a liquid phase or a gas-liquid mixed phase, and liquid back can be suppressed.

[0049] In the subsequent S13, the rotational speed of the compressor 151 is increased. For example, an increase correction is performed so that the target rotational speed gradually increases. Thereby, the decrease amount of the refrigerant flow rate Q can be suppressed, and the decrease in the heating performance can be suppressed.

[0050] In S14, it is determined whether or not a predetermined time ts has elapsed since the switching request from circuit A to circuit B. The process of S14 is repeated until the predetermined time ts elapses, and when the predetermined time ts elapses, the process proceeds to S15.

[0051] In S15, after switching from circuit A to circuit B, the process proceeds to S16. In S16, after returning the target SH and the target rotational speed of the compressor 151 to their normal control values, this routine is terminated. The normal control values of the target SH and the target rotational speed of the compressor 151 are set according to the heating demand of the air conditioner 2, the degree of cooling demand, the temperature rise demand of the battery 200, the degree of cooling demand, etc. Note that the predetermined temperature S, the predetermined time ts, the increase correction amount of the target SH, the increase correction amount of the target rotational speed, etc. are determined in advance through experiments or the like and stored in the memory 502.

[0052] According to the present embodiment, when in the first mode (circuit A) where there is a heating demand and a cooling demand for the battery 200, the ECU 500 controls the expansion valve opening degree K of the electric expansion valve 155 to a predetermined opening degree, and the refrigerant exchanges heat with the low-temperature side heat medium that has absorbed the heat of the battery 200 in the chiller 160, thereby performing cooling of the battery 200 and heating of the vehicle interior. In the second mode (circuit B) where there is a heating demand and no cooling demand, since the low-temperature side heat medium does not flow through the heat exchanger of the battery 200, the heat of the battery 200 is not used for heating. When switching from the first mode to the second mode, the ECU 500 reduces the expansion valve opening degree K of the electric expansion valve 155 to be smaller than the predetermined opening degree for a predetermined time ts, and then switches from the first mode to the second mode. Thereby, during the predetermined time ts, the refrigerant flow rate Q decreases and the dryness (quality) of the refrigerant increases. Therefore, even if there is a response delay in the change of the opening degree of the electric expansion valve 155, the occurrence of liquid back when switching from the first mode to the second mode can be suppressed.

[0053] According to the present embodiment, in the second mode (circuit B), since the refrigerant exchanges heat with the low-temperature side heat medium that has absorbed the heat of at least one of the motor PCU 133, the oil cooler 135, and the outside air in the chiller 160, heating is performed. Therefore, heating of the air conditioner 2 can be performed using the heat of at least one of the motor PCU 133, the oil cooler 135, and the outside air.

[0054] According to the present embodiment, the ECU 500 controls the expansion valve opening degree K of the electric expansion valve 155 so that the superheat degree of the refrigerant flowing out of the chiller 160 reaches the SH target value, and increases and corrects the SH target value for a predetermined time ts to make the expansion valve opening degree K smaller than the predetermined opening degree, and increases the rotation speed of the compressor 151 for the predetermined time ts. Since the rotation speed of the compressor is increased for the predetermined time ts, it is possible to suppress the decrease in the refrigerant flow rate Q while increasing the superheat degree of the refrigerant flowing out of the chiller, and it is possible to reduce the decrease in the heating performance before switching from the first mode to the second mode.

[0055] In the above embodiment, when switching from the first mode (circuit A) to the second mode (circuit B), when the ECU 300 predicts that the temperature of the low-temperature side heat medium flowing into the chiller 160 will drop below a predetermined temperature S (positive determination in S11), for a predetermined time ts, the expansion valve opening degree K of the electric expansion valve 155 is made smaller than the predetermined opening degree. As a result, when switching from circuit A to circuit B, when it is predicted that the temperature of the low-temperature side heat medium flowing into the chiller 160 is less than the predetermined temperature S and there is a high possibility that liquid back will not occur, the refrigerant flow rate Q flowing into the chiller does not decrease, so the decrease in heating performance can be reduced.

[0056] Note that S11 may be omitted, and S12 may be executed regardless of the magnitude of the estimated temperature drop ΔTi.

[0057] Further, when a large heating performance is required by the air conditioner 2, the heating heater 112 provided in the first circuit 110 may be energized to perform heating. Note that the heating heater 112 may not be provided.

[0058] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present disclosure is shown not by the description of the above embodiments but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Description of Reference Numerals

[0059] 1 Vehicle, 2 Air conditioner, 100 Thermal management circuit, 110 First circuit, 120 Second circuit (low-temperature side circuit), 130 Third circuit (low-temperature side circuit), 133 PCU, 140 Capacitor, 150 Refrigerant circuit, 155 Electric expansion valve, 160 Chiller, 170 Low-temperature radiator, 200 Battery, 500 ECU.

Claims

1. A vehicle thermal management device comprising a compressor that compresses and discharges refrigerant flowing out from a chiller, a condenser that dissipates heat of the refrigerant discharged from the compressor, and an expansion valve that decompresses the refrigerant flowing out from the condenser, wherein the chiller has a refrigerant circuit that exchanges heat between the refrigerant decompressed by the expansion valve and a low-temperature-side heat medium, a low-temperature-side circuit having heat exchange equipment that absorbs heat from the heat of a battery, the heat of a vehicle drive device, and the heat of outside air in the low-temperature-side heat medium, an air conditioner that performs heating using the heat dissipation of the condenser, and a control device, wherein the control device in a first state where there is a heating demand and a cooling demand for the battery, controls the opening degree of the expansion valve to a predetermined opening degree so that the refrigerant exchanges heat with the low-temperature-side heat medium that has absorbed the heat of the battery in the chiller, thereby performing cooling of the battery and heating, when switching from the first state to a second state where there is a heating demand and no cooling demand, is configured to reduce the opening degree of the expansion valve to be smaller than the predetermined opening degree for a predetermined period and then switch from the first state to the second state, a vehicle thermal management device in which the low-temperature-side heat medium does not flow through the heat exchanger of the battery in the second state.

2. The vehicle thermal management device according to claim 1, wherein in the second state, the refrigerant exchanges heat with the low-temperature-side heat medium that has absorbed heat from at least one of the vehicle drive device and the outside air in the chiller, thereby performing heating.

3. The control device when predicting that the temperature of the low-temperature-side heat medium flowing into the chiller will drop below a predetermined temperature when switching from the first state to the second state, reduces the opening degree of the expansion valve to be smaller than the predetermined opening degree for the predetermined period. The vehicle thermal management device according to claim 2.

4. The control device controls the opening degree of the expansion valve so that the superheat degree of the refrigerant flowing out from the chiller reaches a target value, and increases the target value during the predetermined period to make the opening degree of the expansion valve smaller than the predetermined opening degree. The vehicle thermal management device according to any one of claims 1 to 3.

5. The control device is configured to increase the rotational speed of the compressor during the predetermined period. The vehicle thermal management device according to claim 4.

Images