JP7831411B2 - Heating system - Google Patents

Description

This disclosure relates to a heating system.

Japanese Patent Publication No. 2020-165604 (Patent Document 1) discloses an air conditioning system for installation in a vehicle. The air conditioning system comprises a heat pump cycle (HPC), a high-temperature side heat transfer medium circuit (heating circuit), and a low-temperature side heat transfer medium circuit. The HPC has a chiller and a condenser. The chiller absorbs heat from the low-temperature side heat transfer medium circuit. The condenser transfers the heat from the HPC to the high-temperature side heat transfer medium circuit. The low-temperature side heat transfer medium circuit has a battery, an outside air heat exchanger, and a three-way valve (switching device). The battery and the outside air heat exchanger each function as heat absorption devices. The three-way valve is used to adjust the amount of heat transferred from the low-temperature side heat transfer medium to the HPC. The modes of the air conditioning system include a heating mode and a cooling-heating mode. In the heating mode, the heat absorbed by the outside air heat exchanger is transferred to the high-temperature side heat transfer medium circuit via the chiller and HPC (outside air is used as the heating heat source). In the cooling/heating mode, heat from the battery is transferred to the high-temperature heat transfer medium circuit via the chiller and HPC (the battery is used as the heating heat source).

Japanese Patent Publication No. 2020-165604

Whether outside air or batteries are used as the heating heat source, the HPC receives heat via the chiller system and transfers heat to the vehicle's heating circuit (heating operation). The switching device switches the connection state between each flow path of the heat transfer medium when changing the heating heat source during heating operation. In this case, the temperature at the heating air outlet changes significantly, potentially reducing the air conditioning comfort inside the vehicle.

This disclosure was made to solve the problems described above, and its purpose is to provide a heating system that suppresses the decline in air-conditioned comfort inside the vehicle cabin.

The heating system of this disclosure is mounted in a vehicle. The heating system comprises a first flow path, a second flow path, and a third flow path, a power storage device, a chiller device, a heat absorption device, a heating circuit, a heat pump cycle, and a switching device. A heat transfer medium can flow through the first, second, and third flow paths. The power storage device is capable of heat exchange with the heat transfer medium in the first flow path. The chiller device is provided in the second flow path. The heat absorption device is provided in the third flow path and is configured to absorb heat from the outside air of the vehicle. The heating circuit heats the passenger compartment of the vehicle. The heat pump cycle performs heating operation by receiving heat from the heat transfer medium in the second flow path via the chiller device and transferring heat to the heating circuit. The switching device is configured to switch the connection state between the first, second, and third flow paths. The connection state includes a first state, a second state, and a third state. In the first state, the first flow path is disconnected from the second and third flow paths, and the second flow path is connected to the third flow path. In the second state, the first flow path is connected to the second flow path and disconnected from the third flow path, and the second flow path is disconnected from the third flow path. In the third state, the first flow path is connected to both the second and third flow paths, and the second flow path is connected to the third flow path. When the switching device switches the connection state from one of the first and second states to the other state during heating operation, it first switches the connection state from the first state to the third state, and then switches the connection state from the third state to the other state.

According to this disclosure, it is possible to suppress the decline in air conditioning comfort inside the vehicle.

This figure shows an example of the overall configuration of the thermal management system (heating system) according to the embodiment. This diagram illustrates the control of a five-way valve by an ECU (Electronic Control Unit) in an embodiment of the invention. This is a diagram illustrating the control of a five-way valve in a comparative example. This is a time chart to explain the switching of connection states between flow paths when the battery starts cooling during heating operation. This flowchart shows the control process procedure for switching the connection state between each flow path using a five-way valve when the battery cooling starts. This is a time chart to explain the control of the five-way valve when the battery cooling is complete during heating operation. This flowchart shows the control process procedure for switching the connection state between each flow path using a five-way valve when the battery cooling is complete.

The embodiments of this disclosure will be described in detail below with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals, and their descriptions will not be repeated.

Figure 1 shows an example of the overall configuration of the thermal management system (heating system) according to the embodiment. Referring to Figure 1, the thermal management system 1 is mounted on a vehicle 5. The vehicle 5 is an electric vehicle such as a battery electric vehicle (BEV). The thermal management system 1 comprises an ECU 50 and a thermal management circuit 100.

The ECU 50 includes a CPU (Central Processing Unit) 51 and a memory 52. The CPU 51 performs various arithmetic operations. The memory 52 includes ROM (Read Only Memory) and RAM (Random Access Memory). The ROM stores the program executed by the CPU 51. The ECU 50 controls the thermal management circuit 100 by outputting control commands to the thermal management circuit 100 in accordance with sensor values from the thermal management circuit 100.

The thermal management circuit 100 is configured to allow a heat transfer medium (refrigerant) to flow through it. The thermal management circuit 100 includes an HT (High Temperature) circuit 110, a radiator 120, an LT (Low Temperature) circuit 130, a water-cooled condenser 141, a chiller (chiller device) 142, a heat pump cycle (HPC) 150, a battery circuit 160, a five-way valve 180 having ports P1 to P5, and temperature sensors 192 to 195.

The HT circuit 110 includes a water pump (W/P) 111, a heater 112, a three-way valve 113, and a heater core 114. The radiator 120 includes a high-temperature (HT) radiator 121 and a low-temperature (LT) radiator 122. The LT circuit 130 includes a flow path FP3, a W/P 131, and a PCU (Power Control Unit) 133. The HPC 150 includes a compressor 151, expansion valves 152 and 155, an evaporator 153, and an EPR (Evaporative Pressure Regulator) 154. The battery circuit 160 includes flow paths FP1 and FP2, a W/P 161, a battery 163, a connection 165, and a flow path BP.

A heat transfer medium can flow through each of the flow paths FP1 and FP2. Flow path FP1 is the flow path from port P1 to connection 165. Flow path FP2 is the flow path from port P2 to connection 165. W/P 111 circulates the heat transfer medium within the HT circuit 110. The water-cooled condenser 141 heats the heat transfer medium in the HT circuit 110 by receiving heat released from the heat transfer medium of the HPC 150. The heater 112 heats the heat transfer medium in the HT circuit 110. The three-way valve 113 switches the inflow destination of the heat transfer medium between the heater core 114 and the HT radiator 121. The heater core 114 warms the air blown into the vehicle interior through heat exchange between the heat transfer medium in the HT circuit 110 and the air. This heats the vehicle interior. The HT circuit 110 is a heating circuit that heats the vehicle interior.

The LT radiator 122 is installed in the flow path FP3. Flow path FP3 is a flow path from port P3 to port P4, through which the heat transfer medium can flow. The LT radiator 122 functions as a heat absorption device that absorbs heat from the outside air when the temperature of the heat transfer medium in flow path FP3 is lower than the temperature of the outside air of the vehicle 5. The W/P 131 circulates the heat transfer medium in flow path FP3. The PCU 133 converts DC power from the battery 163 into AC power and supplies it to the vehicle 5's drive motor.

The water-cooled condenser 141 releases heat from the heat transfer medium of the HPC 150 to the heat transfer medium of the HT circuit 110. The chiller 142 is located in the flow path FP2 and exchanges heat between the heat transfer medium of the HPC 150 and the heat transfer medium of the battery circuit 160 (flow path FP2).

The heat transfer medium (gas-phase or liquid-phase refrigerant) of the HPC 150 circulates within a circuit passing through the evaporator 153 or a circuit passing through the water-cooled condenser 141. The HPC 150 is configured to perform heating operation by receiving heat from the heat transfer medium in the flow path FP2 via the chiller 142 and transferring heat to the HT circuit 110.

The compressor 151 compresses the gaseous refrigerant circulating in the HPC 150. The rotational speed of the compressor 151 is controlled according to the deviation between the target value and the current value of the outlet temperature. The water-cooled condenser 141 condenses the gaseous refrigerant into a liquid refrigerant by releasing heat from the gaseous refrigerant, which has been compressed and is now high temperature and high pressure. The high temperature and high pressure refrigerant compressed by the compressor 151 dissipates heat to the heat transfer medium (hot water) circulating in the HT circuit 110 through heat exchange in the water-cooled condenser 141. The heat from the heated hot water is dissipated by the heater core 114, and the heated air (heated air) is sent from the outlet into the passenger compartment to heat the passenger compartment. The expansion valves 152 and 155 each reduce the pressure of the liquid refrigerant by expanding the high-pressure liquid refrigerant. The EPR 154 adjusts the pressure inside the evaporator 153 to be approximately constant by controlling the flow rate of the heat transfer medium flowing in from the evaporator 153. The chiller 142 evaporates the liquid-phase refrigerant, which has been depressurized by the expansion valve 155. As a result, heat is removed from the heat transfer medium circulating in the battery circuit 160, and this heat transfer medium is cooled.

The heat transfer fluid circulating in the battery circuit 160 flows through one or both of the first and second circulation circuits. The first circulation circuit is the path W/P 161 – chiller 142 – five-way valve 180 – battery 163 – W/P 161. The second circulation circuit is the path W/P 161 – chiller 142 – five-way valve 180 – flow path BP – W/P 161.

W/P 161 circulates the heat transfer medium within the battery circuit 160. The chiller 142 cools the heat transfer medium circulating in the battery circuit 160 through heat exchange between the heat transfer medium circulating in the HPC 150 and the heat transfer medium circulating in the battery circuit 160. The battery 163 is located in the flow path FP1 and is capable of heat exchange with the heat transfer medium in the flow path FP1. The battery 163 stores the power for the vehicle 5's operation. The battery 163 can be cooled by the heat transfer medium in the flow path FP1.

The flow path BP is a flow path from port P5 to connection point 165 through which the heat transfer medium can flow. Flow path BP is a bypass flow path through which the heat transfer medium bypasses the battery 163. Flow path BP is connected to connection point 165. Connection point 165 is located in the downstream portion of flow path FP1 beyond the battery 163 and in the upstream portion of flow path FP2 beyond the chiller 142. Flow path BP is configured to be connectable to the downstream portion of flow path FP3 beyond the LT radiator 122 via a five-way valve 180.

The five-way valve 180 has ports P1 to P5. Port P1 is connectable to the flow path FP1. Port P2 is connectable to the flow path FP2. Ports P3 and P4 are connectable to the upstream and downstream portions of the flow path FP3, respectively, beyond the LT radiator 122. Port P5 is connectable to the flow path BP. The five-way valve 180 is a switching device that switches the connection state between the flow paths FP1 to FP3 and BP, and is controlled by the ECU 50.

Temperature sensor 192 detects the radiator water temperature Tr, which is the temperature of the heat transfer medium flowing through the LT radiator 122 (temperature of the heat transfer medium in flow path FP3). The radiator water temperature Tr corresponds to the temperature of the heat transfer medium in the downstream portion of flow path FP3 beyond the LT radiator 122. Temperature sensor 193 detects the temperature of the heat transfer medium in flow path FP2 (chiller water temperature Tc). In this example, the chiller water temperature Tc corresponds to the temperature of the heat transfer medium in the upstream portion of flow path FP2 beyond the chiller 142. Temperature sensor 194 detects the temperature of the heat transfer medium in flow path FP1 (battery water temperature Tb). Temperature sensor 195 detects the temperature of the heat transfer medium flowing through the PCU 133 (power trainer water temperature Tp). The power trainer water temperature Tp may also be used as the temperature of the heat transfer medium in flow path FP3.

Figure 2 is a diagram illustrating the control of the five-way valve 180 by the ECU 50 in the embodiment. Referring to Figure 2, the ECU 50 controls the five-way valve 180 so that the connection state between the flow paths FP1, FP2, FP3 and BP is in the first state, second state, or third state.

The first state (upper part of Figure 2) corresponds to the connection state between each flow path when outside air is used as the heating heat source. In the first state, flow path FP1 is disconnected from flow paths FP2, FP3, and BP, flow path FP2 is connected to flow paths FP3 and BP, and flow path FP3 is connected to flow path BP. The heat transfer medium passing through the chiller 142 circulates through the closed circuit formed by flow paths FP2, FP3, and BP. The ECU 50 achieves the first state by controlling the five-way valve 180 so that port P1 is disconnected from ports P2 to P5, ports P2 and P3 are connected, and ports P4 and P5 are connected. In the first state, the HPC 150 is performing heating operation, and the battery 163 is not being cooled.

In the first state, flow path FP1 is isolated from flow paths FP2, FP3, and BP. Therefore, the battery water temperature Tb may deviate from the chiller water temperature Tc or the radiator water temperature Tr (or powertrain water temperature Tp). For example, when outside air is used as a heating source in a low-temperature winter environment, the radiator water temperature Tr is lower than the ambient temperature (e.g., 0°C). As a result, the battery water temperature Tb in the first state may be significantly higher than the radiator water temperature Tr. The deviation between the radiator water temperature Tr and the battery water temperature Tb becomes more pronounced when the cooling start temperature of the battery 163 is set high and the cooling frequency of the battery 163 is low from an energy-saving perspective.

The second state (lower part of Figure 2) corresponds to the connection state between each flow path when the battery 163 is used as a heating heat source. In the second state, flow path FP1 is connected to flow path FP2 and disconnected from flow path FP3, flow path FP2 is disconnected from flow path FP3, and flow path FP3 is disconnected from flow path BP. The heat transfer medium passing through the chiller 142 circulates in a closed circuit (dotted line) formed by flow paths FP1 and FP2. The ECU 50 achieves the second state by controlling the five-way valve 180 so that ports P1 and P2 are in communication, ports P3 and P4 are in communication, and port P5 is disconnected from ports P1 to P4. In the second state, heat from the battery 163 is supplied to the HT circuit 110 via the heat transfer fluid in the flow path FP1, the heat transfer fluid in the flow path FP2, the chiller 142, and the HPC 150 (Figure 1) (the HPC 150 performs heating operation), and the battery 163 is cooled.

In the second state, flow path FP3 is disconnected from flow paths FP1, FP2, and BP. Therefore, the radiator water temperature Tr (or powertrain water temperature Tp) may deviate from the battery water temperature Tb or chiller water temperature Tc.

The ECU 50 controls the five-way valve 180 so that the connection state between each flow path switches from one state (first state or second state) to the other state when cooling of the battery 163 begins or ends during heating operation. For example, when cooling of the battery 163 begins, the ECU 50 controls the five-way valve 180 so that the connection state switches from the first state to the second state in order to change the heating heat source from the outside air to the battery 163. When cooling of the battery 163 ends, the ECU 50 controls the five-way valve 180 so that the connection state switches from the second state to the first state in order to change the heating heat source from the battery 163 to the outside air.

As described above, when the ECU 50 switches its connection state from the first state to the second state, or from the second state to the first state, the chiller water temperature Tc may change rapidly, potentially reducing the comfort level of the air conditioning system (see below for details).

Therefore, when the ECU 50 switches the connection state between each flow path from one of the first or second states to the other state during heating operation (when starting or ending the cooling of the battery 163), it controls the five-way valve 180 to perform a specific switching operation. This operation involves switching the connection state from the first state to the third state (the middle part of Figure 2), and then switching the connection state from the third state to the other state.

In the third state, flow path FP1 is connected to flow paths FP2, FP3, and BP, flow path FP2 is connected to flow paths FP3 and BP, and flow path FP3 is connected to flow path BP. The ECU 50 achieves the third state by controlling the five-way valve 180 so that ports P1, P4, and P5 are in communication, and ports P2 and P3 are in communication.

In the third state, paths R1 and R2 are formed. Path R1 is the path through which the heat transfer medium flows into the chiller 142 via the flow paths FP3, BP, and the connection part 165. Path R2 is the path through which the heat transfer medium flows into the chiller 142 via the flow paths FP3, FP1, and the connection part 165.

The aforementioned specific switching operation includes a first operation performed when the cooling of battery 163 begins, and a second operation performed when the cooling of battery 163 begins to end. The first operation involves switching the connection state from the first state to the third state, and then switching the connection state from the third state to the second state (hatched arrow). The second operation involves switching the connection state from the second state to the third state, and then switching the connection state from the third state to the first state (white arrow).

According to the first operation, when cooling of the battery 163 begins, the connection state temporarily takes a third state before switching from the first state to the second state. In the third state, the closed circuit (chiller-battery circulation circuit) through which the heat transfer fluid circulates through the chiller 142 and battery 163 is larger than the chiller-battery circulation circuit in the second state (dotted line) in that it includes the flow path FP3. Therefore, the amount of heat transfer fluid in the chiller-battery circulation circuit in the third state is greater than the amount of heat transfer fluid in the chiller-battery circulation circuit in the second state. Consequently, the temperature change of the heat transfer fluid in the chiller-battery circulation circuit immediately after switching from the first state to the third state (temperature change associated with the connection of flow paths FP1 and FP2) is smaller than the temperature change of the heat transfer fluid in the chiller-battery circulation circuit immediately after directly switching from the first state to the second state. This reduces the influence of the heat transfer fluid in flow path FP2 on the heat of the battery 163 when cooling of the battery 163 begins. Therefore, the change in chiller water temperature Tc can be reduced.

According to the second operation, when the cooling of the battery 163 is complete, the connection state temporarily takes the third state before switching from the second state to the first state. In the third state, the closed circuit (chiller-radiator circulation circuit) through which the heat transfer medium circulates through the chiller 142 and LT radiator 122 is larger than the chiller-radiator circulation circuit in the first state (solid line) in that it includes the flow path FP1. Therefore, the amount of heat transfer medium in the chiller-radiator circulation circuit in the third state is greater than the amount of heat transfer medium in the chiller-radiator circulation circuit in the first state. Consequently, the temperature change of the heat transfer medium in the chiller-battery circulation circuit immediately after the switch from the second state to the third state (temperature change associated with the connection of flow paths FP2 and FP3) is smaller than the temperature change of the heat transfer medium in the chiller-battery circulation circuit immediately after the direct switch from the second state to the first state. This reduces the influence that the heat transfer medium in flow path FP2 receives from the heat transfer medium in flow path FP3 when the cooling of the battery 163 is complete. Therefore, changes in chiller water temperature Tc can be reduced.

Thus, the first and second operations can mitigate rapid changes in chiller water temperature Tc. As a result, a decrease in the comfort level of the vehicle's air conditioning can be suppressed. Furthermore, the operation of the heater 112, which is necessary to compensate for the decrease in air conditioning comfort caused by rapid changes in chiller water temperature Tc, is not required, allowing for the use of the highly efficient HPC 150. Therefore, power consumption during vehicle interior heating can be reduced.

In this embodiment, both paths R1 and R2 are formed in the third state. Therefore, the heat transfer fluid in path FP3 flows into the chiller 142 through both paths FP1 and FP2. In this case, the heat transfer fluid in the downstream portion of path FP1 (below the battery 163) and the heat transfer fluid in path BP are mixed at the connection point 165, and the mixed heat transfer fluid flows into the chiller 142. The temperature of the mixed heat transfer fluid is closer to the chiller water temperature Tc before the connection state switch than the temperature of the heat transfer fluid at the connection point 165 in the case where the heat transfer fluid flows into the chiller 142 through only one of paths R1 or R2. Therefore, the change in chiller water temperature Tc can be reduced more effectively than in the above case.

For example, when cooling of the battery 163 begins (from the first state to the third state), if the heat transfer medium flows into the chiller 142 only through path R1, then only the relatively high-temperature heat transfer medium that has passed through the battery 163 in path FP1 flows into the chiller 142 through the connection part 165. On the other hand, in this embodiment, the relatively low-temperature heat transfer medium supplied from path FP3 through path BP also flows into the connection part 165 and mixes with the relatively high-temperature heat transfer medium at the connection part 165. As a result, since the mixed, medium-temperature heat transfer medium flows into the chiller 142, the rapid change in chiller water temperature Tc can be more effectively mitigated than in the above case where only the high-temperature heat transfer medium flows into the chiller 142.

Similarly, when the cooling of the battery 163 is complete (second state → third state), if the heat transfer medium flows into the chiller 142 only through path R1, then only the relatively low-temperature heat transfer medium that has passed through the battery 163 in path FP1 flows into the chiller 142 through the connection part 165. On the other hand, in this embodiment, the relatively high-temperature heat transfer medium supplied from path FP3 through path BP also flows into the connection part 165 and mixes with the relatively low-temperature heat transfer medium at the connection part 165. As a result, the medium-temperature heat transfer medium flows into the chiller 142, effectively mitigating rapid changes in the chiller water temperature Tc.

Figure 3 illustrates the control of the five-way valve 180 by the ECU in a comparative example. In this comparative example, when the cooling of the battery 163 during heating operation begins or ends, the connection state between each flow path switches directly from one of the first and second states to the other.

Referring to Figure 3, when cooling of the battery 163 begins, the ECU of the comparative example controls the five-way valve 180 so that the connection state between each flow path switches directly from the first state to the second state (hatched arrow). This connects flow path FP2 to flow path FP1 and disconnects it from flow path FP3. As a result, the heat transfer medium flowing through the chiller 142 no longer flows through the LT radiator 122, and instead flows through the battery 163 (circulating through the closed circuit formed by flow paths FP1 and FP2). Therefore, if the battery water temperature Tb deviates from the chiller water temperature Tc when cooling of the battery 163 begins, the chiller water temperature Tc may change rapidly immediately after switching from the first state to the second state, influenced by the battery water temperature Tb.

When the cooling of the battery 163 is complete, the ECU controls the five-way valve 180 so that the connection state between each flow path switches directly from the second state to the first state (white arrow). This disconnects flow path FP2 from flow path FP1 and connects it to flow path FP3. As a result, the heat transfer fluid flowing through the chiller 142 no longer flows through the battery 163, and instead flows through the LT radiator 122 (circulating through the closed circuit formed by flow paths FP2, FP3, and BP). Therefore, if the radiator water temperature Tr (powertrain water temperature Tp) deviates from the chiller water temperature Tc when the cooling of the battery 163 is complete, the chiller water temperature Tc may change rapidly immediately after the switch from the second state to the first state due to the influence of the radiator water temperature Tr.

Rapid changes in chiller water temperature Tc affect the HT circuit 110 via the HPC 150, leading to significant temperature fluctuations at the heating air outlet. As a result, the air conditioning comfort inside the vehicle may decrease. While the heater 112 can be activated to compensate for this decrease in comfort, this increases power consumption compared to high-efficiency heating using the HPC 150.

As mentioned above, the compressor rotation speed is controlled according to the deviation between the target temperature and the current temperature at the heating air outlet. However, if the chiller heat absorption changes rapidly, the compressor rotation speed increases only after the widening of this deviation is detected. In other words, the increase in compressor rotation speed lags behind the switching timing between the first and second states. Therefore, it is difficult to suppress rapid changes in chiller heat absorption (chiller water temperature Tc) by adjusting the compressor rotation speed after switching from the first to the second state, or from the second state to the first state.

Furthermore, if the chiller's heat absorption rate changes rapidly, the refrigerant's dryness may change, potentially preventing the heat transfer medium from being completely vaporized by the chiller 142. That is, the heat transfer medium at the compressor 151 inlet may become a gas-liquid mixed state (a mixture of gaseous and liquid refrigerants). This is undesirable from the standpoint of protecting the compressor 151.

Thus, in the comparative example, problems such as a decrease in air conditioning comfort, increased power consumption, and gas-liquid mixed phase of the heat transfer medium at the compressor 151 inlet may occur when the cooling of the battery 163 starts or ends. On the other hand, in the embodiment (Figure 2), such problems can be suppressed.

Figure 4 is a time chart illustrating the switching of connection states between flow paths FP1-FP3 and BP at the start of cooling of battery 163 during heating operation. Referring to Figure 4, the horizontal axis represents elapsed time. The vertical axis, from top to bottom, represents the presence/absence of a cooling request for battery 163, the circuit to which chiller 142 is connected (LT circuit 130/battery circuit 160), chiller water temperature Tc, battery water temperature Tb, radiator water temperature Tr, power trainer water temperature Tp, and the connection state between each flow path.

The time evolution of each parameter in the embodiment and comparative example is shown by solid and dashed lines, respectively. In this comparative example, the connection state is directly switched from the first state to the second state.

During period TP1 prior to time ta, the connection state is the first state. At time ta, the battery water temperature Tb rises to the cooling start temperature TS, and a cooling request for battery 163 is generated. The ECU 50 of this embodiment controls the five-way valve 180 to perform a first operation in response to the cooling request. Specifically, at time ta, the ECU 50 switches the connection state between each flow path from the first state to the third state, and maintains the third state during period TP2. Period TP2 continues until the chiller water temperature Tc rises by a reference temperature ΔPT1 (until time tb). At time tb, the ECU 50 switches the connection state from the third state to the second state and maintains it in the second state during period TP3.

The temperature difference between the battery water temperature Tb and the chiller water temperature Tc or radiator water temperature Tr (powertrain water temperature Tp) is also expressed as the temperature difference ΔT1 (= |Tb - Tc|, |Tb - Tr|, or |Tb - Tp|). The temperature difference ΔT1 is related to the change in chiller water temperature Tc at the start of cooling of the battery 163. For example, if the temperature difference ΔT1 is large enough to be greater than or equal to the threshold TH1 in the first state before the start of cooling of the battery 163, then it is predicted that the chiller water temperature Tc will change rapidly if the connection state is directly switched from the first state to the second state at the start of cooling of the battery 163. Otherwise, because the temperature difference ΔT1 is small, it is predicted that the chiller water temperature Tc will not change rapidly at the time of switching.

Therefore, when switching the connection state from the first state to the second state, the ECU 50 may control the five-way valve 180 to execute the first operation when the temperature difference ΔT1 is greater than or equal to the threshold TH1. On the other hand, when the temperature difference ΔT1 is less than the threshold TH1, the ECU 50 may control the five-way valve 180 to switch directly to the second state without switching the connection state from the first state to the third state.

With this type of control, if a rapid change in chiller water temperature Tc is not predicted, heating of the vehicle compartment using battery 163 as the heating heat source can be started immediately.

Figure 5 is a flowchart showing the control process procedure for switching the connection state between each flow path using the five-way valve 180 when cooling of the battery 163 begins. The process shown in this flowchart is initiated in response to a cooling request for the battery 163. Hereafter, steps will be abbreviated as S.

Referring to Figure 5, in S105, the ECU 50 determines whether the temperature difference ΔT1 is greater than or equal to the threshold TH1 (S105).

If the temperature difference ΔT1 is less than the threshold TH1 (NO in S105), the ECU 50 controls the five-way valve 180 to directly switch the connection state of the flow paths FP1-FP3 and BP from the first state to the third state to the second state (S120). Otherwise (YES in S105), the ECU 50 controls the five-way valve 180 to switch the connection state of the flow paths FP1-FP3 and BP from the first state to the third connection state (S110). Subsequently, the ECU 50 controls the five-way valve 180 to switch the connection state of the flow paths FP1-FP3 and BP from the third state to the second connection state (S115).

Figure 6 is a time chart illustrating the control of the five-way valve 180 at the end of cooling of the battery 163 during heating operation. Referring to Figure 6, the parameters on the horizontal and vertical axes are the same as those shown in Figure 4.

The time evolution of each parameter in the embodiment and comparative example is shown by solid and dashed lines, respectively. In this comparative example, the connection state is directly switched from the second state to the first state.

During period TP1a prior to time tc, the connection state is in the second state. At time tc, the cooling request for battery 163 disappears. As a result, the ECU 50 of this embodiment controls the five-way valve 180 to perform the second operation. Specifically, at time tc, the ECU 50 switches each connection state from the second state to the third state, and maintains the third state during period TP2a. Period TP2a continues until the chiller water temperature Tc drops by a reference temperature ΔPT2 (until time td). At time td, the ECU 50 switches the connection state from the third state to the first state and maintains it in the first state during period TP3a.

In this example, the chiller water temperature Tc at the end of battery cooling is lower than that at the start of battery cooling (Figure 4), but even if this is not the case, the second operation can suppress rapid changes in the chiller water temperature Tc.

The temperature difference between the radiator water temperature Tr (powertrain water temperature Tp) and the battery water temperature Tb or chiller water temperature Tc is also expressed as the temperature difference ΔT2 (= |Tr - Tb|, |Tr - Tc|, |Tp - Tb|, or |Tp - Tc|). The temperature difference ΔT2 is related to the change in chiller water temperature Tc at the end of cooling of battery 163. For example, if the temperature difference ΔT2 is large enough to exceed the threshold TH2 in the second state before the end of cooling of battery 163, then it is predicted that the chiller water temperature Tc will change rapidly if the connection state is directly switched from the second state to the first state at the end of cooling of battery 163. Otherwise, the temperature difference ΔT2 is small, and it is predicted that the chiller water temperature Tc will not change rapidly.

Therefore, when switching the connection state from the second state to the first state, the ECU 50 may control the five-way valve 180 to execute the second operation when the temperature difference ΔT2 is greater than or equal to the threshold TH2. On the other hand, when the temperature difference ΔT2 is less than the threshold TH2, the ECU 50 may control the five-way valve 180 to switch directly to the first state without switching the connection state from the second state to the third state.

With this type of control, if a rapid change in chiller water temperature Tc is not predicted, the heating source can be switched early from battery 163 to outside air.

Figure 7 is a flowchart showing the control process for switching the connection state between each flow path using the five-way valve 180 when the cooling of the battery 163 is complete. The process shown in this flowchart is initiated in response to the disappearance of the cooling request for the battery 163.

Referring to Figure 7, in S205, the ECU 50 determines whether the temperature difference ΔT2 is greater than or equal to the threshold TH2 (S205).

If the temperature difference ΔT2 is less than the threshold TH2 (NO in S205), the ECU 50 controls the five-way valve 180 to directly switch the connection state of the flow paths FP1-FP3 and BP from the second state to the third state to the first state (S220). Otherwise (YES in S205), the ECU 50 controls the five-way valve 180 to switch the connection state of the flow paths FP1-FP3 and BP from the second state to the third connection state (S210). Subsequently, the ECU 50 controls the five-way valve 180 to switch the connection state of the flow paths FP1-FP3 and BP from the third state to the first connection state (S215).

As described above, according to this embodiment, the decrease in the air conditioning comfort inside the vehicle can be suppressed.

<Other variations>
If the thermal management circuit 100 includes an indoor capacitor, the heat from the heat transfer medium of the battery circuit 160 may be dissipated into the vehicle compartment via the chiller 142 and the indoor capacitor, thereby heating the vehicle compartment.

The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope of the claims are intended to be included.

1. Thermal management system, 5. Vehicle, 50. ECU, 100. Thermal management circuit, 122. LT radiator, 142. Chiller, 163. Battery, 180. Five-way valve, BP, FP1, FP2, FP3. Flow path.

Claims (5)

A heating system installed in a vehicle,
A first channel, a second channel, and a third channel through which a heat transfer medium can flow,
A power storage device capable of exchanging heat with the heat transfer medium in the first flow path,
A chiller device provided in the second flow path,
A heat absorption device provided in the third flow path and configured to absorb heat from the outside air of the vehicle,
A heating circuit for heating the passenger compartment of the aforementioned vehicle,
A heat pump cycle that performs heating operation by receiving heat from the heat transfer medium in the second flow path via the chiller device and transferring the heat to the heating circuit,
The system includes a switching device configured to switch the connection state between the first channel, the second channel, and the third channel,
The aforementioned connection state is,
A first state in which the first channel is disconnected from the second channel and the third channel, and the second channel is connected to the third channel,
A second state in which the first flow path is connected to the second flow path and disconnected from the third flow path, and the second flow path is disconnected from the third flow path,
This includes a third state in which the first flow path is connected to the second flow path and the third flow path, and the second flow path is connected to the third flow path,
The switching device is a heating system that, when switching the connection state from one of the first and second states to the other state during heating operation, first switches the connection state from one state to the third state, and then switches the connection state from the third state to the other state. If the temperature difference between the temperature of the heat medium in the second channel or the temperature of the heat medium in the third channel and the temperature of the heat medium in the first channel is defined as the first temperature difference,
When the switching device switches the connection state from the first state to the second state,
The operation is performed when the first temperature difference is equal to or greater than the first threshold.
The heating system according to claim 1, wherein when the first temperature difference is less than the first threshold, the connection state is switched to the second state without switching from the first state to the third state. If the temperature difference between the temperature of the heat medium in the first channel or the temperature of the heat medium in the second channel and the temperature of the heat medium in the third channel is defined as the second temperature difference,
When the switching device switches the connection state from the second state to the first state,
The operation is performed when the second temperature difference is equal to or greater than the second threshold.
The heating system according to claim 1, wherein when the second temperature difference is less than the second threshold, the connection state is switched to the first state without switching from the second state to the third state. Further equipped with a bypass channel,
The bypass channel is connected to a connection point located in the portion of the first channel downstream of the energy storage device and in the portion of the second channel upstream of the chiller device, and is configured to be connectable to the portion of the third channel downstream of the heat absorption device.
The heating system according to any one of claims 1 to 3, wherein the third state includes a state in which a first path is formed through which the heat transfer medium flows into the chiller device via the third flow path, the bypass flow path, and the connection part, and a second path is formed through which the heat transfer medium flows into the chiller device via the third flow path, the first flow path, and the connection part. The aforementioned switching device is
A first port connectable to the first flow path,
A second port connectable to the second flow path,
A third port that can be connected to the portion of the third flow path upstream of the heat absorption device,
A fourth port that can be connected to the portion of the third flow path downstream of the heat absorption device,
It has a fifth port that can be connected to the bypass channel,
The first state includes a state in which the first port is disconnected from the second to fifth ports, the second port is in communication with the third port, and the fourth port is in communication with the fifth port.
The second state includes a state in which the first port is in communication with the second port, the third port is in communication with the fourth port, and the fifth port is disconnected from the first to the fourth ports.
The heating system according to claim 4, wherein the third state includes a state in which the first port communicates with the fourth and fifth ports, and the second port communicates with the third port.