Diagnostic device for a flow switching valve

Abstract

The present application provides a kind of diagnostic device of flow path switching valve, by using the information of temperature difference before and after sending switching signal to determine switching to given connection state, it can determine that flow path switching valve normal action.Diagnostic device has the processing circuit that sends the switching signal that makes flow path switching valve act to flow path switching valve.In the case where the first switching pre-temperature difference PRTD1A is greater than the value of given value DA and the second switching post-temperature difference POTD2A is less than or equal to given value DA and the value obtained by subtracting the lower limit value LL in the second state from the second water temperature WT2 from the third switching pre-temperature difference PRTD3A is greater than the second switching post-temperature difference POTD2A (S16: Yes), processing circuit determines that flow path switching valve normal action (S17).

Description

Technical Field

[0001] This invention relates to a diagnostic device for a flow path switching valve. Background Technology

[0002] Patent Document 1 discloses a switching valve fault determination device that determines whether a switching valve in the engine's coolant circuit is operating normally. To determine whether the switching valve is operating normally, the device sends an opening request to the switching valve. If, after sending the opening request, the temperature readings of the upstream and downstream water temperature sensors are nearly identical, the device determines that the switching valve is operating normally. If the device cannot determine normal operation after a certain period, it determines that a fault has occurred.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2012-102690 Summary of the Invention

[0004] There are also cooling water circuits equipped with flow path switching valves. These valves are configured to switch the cooling water circulation path, rather than simply switching between opening and closing paths in the cooling water circuit to allow or block cooling water flow. In this case, even before the flow path switching valve changes the connection between the upstream and downstream flow paths, the difference between the temperature readings from the water temperature sensor upstream of the valve and the water temperature readings from the water temperature sensor downstream of the valve may be almost identical. In this situation, the aforementioned valve failure detection device cannot determine whether the flow path switching valve is functioning correctly.

[0005] The diagnostic device for the flow path switching valve used to solve the above-mentioned problems is a device installed in the cooling water circuit of a vehicle that selectively switches the connection state of the upstream and downstream flow paths from multiple connection states to switch the cooling water circulation path. The diagnostic device includes a processing circuit that sends a switching signal to the flow path switching valve to activate it. The upstream water temperature before the switching signal is sent is defined as the upstream water temperature before the switch, and the downstream water temperature before the switching signal is sent is defined as the downstream water temperature before the switch. The upstream water temperature after a predetermined time has elapsed since the switching signal was sent is defined as the upstream water temperature after the switch. The downstream water temperature after the predetermined time has elapsed since the switching signal is sent is defined as the downstream water temperature after the switch. When the processing circuit sends a switching signal to the flow path switching valve to switch the connection state to a predetermined connection state among the multiple connection states, it determines that the flow path switching valve is operating normally based on the fact that the difference between the upstream water temperature before the switch and the downstream water temperature before the switch (i.e., the temperature difference before the switch) and the difference between the upstream water temperature after the switch and the downstream water temperature after the switch (i.e., the temperature difference after the switch) both meet the respective specified conditions.

[0006] Invention Effects

[0007] The diagnostic device described above determines the switch to a predetermined connection state by using the temperature difference information before and after sending the switching signal, and can determine that the flow path switching valve is operating normally. Attached Figure Description

[0008] Figure 1 This is a schematic diagram showing the structure of the cooling water circuit of a vehicle equipped with the diagnostic device of the first embodiment.

[0009] Figure 2 It means used for Figure 1 The flowchart shows a series of processes performed by the processing circuit to diagnose the flow path switching valve.

[0010] Figure 3 This is a diagram showing the conditions specified for the temperature difference before and after switching in the diagnostic device of the first embodiment.

[0011] Figure 4 This is a flowchart illustrating a series of processes performed by the processing circuit of the diagnostic device in the second embodiment to diagnose the flow path switching valve.

[0012] Figure 5 This is a diagram showing the conditions specified for the temperature difference before and after switching in the diagnostic device of the second embodiment. Detailed Implementation

[0013] (First Embodiment)

[0014] The following is for reference. Figures 1-3 The diagnostic device of the first embodiment will be described.

[0015] <Temperature Management System 1 Installed in Vehicles>

[0016] like Figure 1 As shown, the vehicle includes: a battery pack 10 that houses multiple battery cells 10A; and a drive motor 51 that uses the electricity stored in the multiple battery cells 10A. Figure 1 In the diagram, multiple battery cells 10A arranged within the battery pack 10 are shown enclosed by a single-dotted line. The drive motor 51 is the power source for the vehicle. The vehicle is an electric vehicle (BEV) that uses only the drive motor 51 as its power source.

[0017] A thermal management system 1 is installed on the vehicle. The thermal management system 1 is a system for maintaining multiple battery cells 10A at appropriate temperatures and cooling multiple on-board devices, including a drive motor 51. The thermal management system 1 includes a cooling water circuit 80 and a diagnostic device 90. A flow path switching valve 20 is provided in the cooling water circuit 80. The diagnostic device 90 includes: a processing circuit 91 that executes programs to perform various processes; and a storage device 92 that stores programs. The processing circuit 91 includes a processor. The storage device 92 is capable of storing various data. Hereinafter, the structure of the cooling water circuit 80 will be described first, followed by an explanation of the diagnostic capabilities of the flow path switching valve 20 based on the diagnostic device 90.

[0018] <Cooling water circuit 80>

[0019] The cooling water circuit 80 is configured to allow cooling water to circulate. Figure 1 In the diagram, the direction of the arrow indicates the flow direction of the cooling water in the cooling water circuit 80. The cooling water is, for example, long-life coolant (LLC).

[0020] like Figure 1 As shown, the cooling water circuit 80 includes a first water jacket 11. Figure 1 As shown by the dashed line, the first water jacket 11 is disposed inside the battery pack 10. Heat exchange occurs between the battery cells 10A housed in the battery pack 10 and the cooling water within the first water jacket 11.

[0021] The cooling water circuit 80 includes a cooler 17 for cooling the cooling water. The cooler 17 is a water-cooled heat exchanger. The cooler 17, for example, performs heat exchange between the air conditioning refrigerant and the cooling water flowing in the cooling water circuit 80. The air conditioning refrigerant is, for example, a hydrofluorocarbon (HFC) refrigerant or a hydrofluoroolefin (HFO) refrigerant.

[0022] The cooling water circuit 80 includes a radiator 30 for cooling the cooling water. The radiator 30 is an air-cooled heat exchanger. The cooling water circuit 80 also includes a second water jacket 32. Figure 1 As shown by the dashed line, the second water jacket 32 ​​is disposed inside the on-board charger 31. Heat exchange occurs between the on-board charger 31 and the cooling water within the second water jacket 32. The on-board charger 31 is an on-board device that generates heat. The on-board charger 31 is an on-board device that converts externally supplied AC power into DC power to charge the battery cell 10A.

[0023] The cooling water circuit 80 includes an oil cooler 40 for heat exchange between the lubricating oil and cooling water that lubricates the drive motor 51. The lubricating oil in... Figure 1 The lubricating oil circulates within the lubricating oil path 50, indicated by a double-dotted line. The lubricating oil within the lubricating oil path 50 is circulated by the oil pump 52.

[0024] The cooling water circuit 80 is equipped with a third water jacket 37. For example... Figure 1 As shown by the dashed line, the third water jacket 37 is located inside the power control unit 36. Heat exchange occurs between the power control unit 36 ​​and the cooling water within the third water jacket 37. The power control unit 36 ​​controls the power supplied to the drive motor 51. The power control unit 36 ​​is an on-board device that generates heat.

[0025] The cooling water circuit 80 includes a cooler flow path 76, a radiator flow path 79, a first flow path 71, a second flow path 72, a third flow path 73, a fourth flow path 74, and a bypass flow path 75. The cooler flow path 76 is a flow path from the outlet 13 of the first water jacket 11 to the inlet 17A of the cooler 17. A storage tank 14, a water pump 15, and a water-to-water heat exchanger 16 are provided in the cooler flow path 76. The outlet 13 is connected to the storage tank 14, which stores cooling water. The storage tank 14 is connected to the water pump 15, which circulates the cooling water. The cooling water discharged from the water pump 15 flows into the inlet 17A after passing through the water-to-water heat exchanger 16. The water-to-water heat exchanger 16 is a water-cooled heat exchanger. The water-to-water heat exchanger 16, for example, performs heat exchange between an air conditioning heat medium and the cooling water flowing in the cooling water circuit 80. The air conditioning heat medium is, for example, LLC.

[0026] The radiator flow path 79 is the flow path from the outlet 30B of the radiator 30 to the inlet 33 of the second water jacket 32.

[0027] The first flow path 71 is the flow path from the outlet 17B of the cooler 17 to the flow path switching valve 20. The second flow path 72 is the flow path from the flow path switching valve 20 to the inlet 12 of the first water jacket 11. The third flow path 73 is the flow path from the outlet 34 of the second water jacket 32 ​​to the flow path switching valve 20. In the third flow path 73, a water pump 35, a third water jacket 37, and an oil cooler 40 are arranged sequentially from upstream to downstream. The fourth flow path 74 is the flow path from the flow path switching valve 20 to the inlet 30A of the radiator 30. The bypass flow path 75 is the flow path from the flow path switching valve 20 to the inlet 17A of the cooler 17. A liquid storage tank 14, a water pump 15, and a water-to-water heat exchanger 16 are arranged in the bypass flow path 75.

[0028] The cooling water circuit 80 includes a first water temperature sensor 61, a second water temperature sensor 62, and a third water temperature sensor 63. The first water temperature sensor 61 measures the temperature of the cooling water in the first flow path 71, i.e., the first water temperature WT1. The second water temperature sensor 62 measures the temperature of the cooling water in the second flow path 72, i.e., the second water temperature WT2. The third water temperature sensor 63 measures the temperature of the cooling water flowing between the water pump 35 and the power control unit 36 ​​in the third flow path 73, i.e., the third water temperature WT3.

[0029] <Flow path switching valve 20>

[0030] The flow path switching valve 20 has a first port P1, a second port P2, a third port P3, a fourth port P4, and a fifth port P5. The first port P1 is connected to the first flow path 71. The second port P2 is connected to the second flow path 72. The third port P3 is connected to the third flow path 73. The fourth port P4 is connected to the fourth flow path 74. The fifth port P5 is connected to the bypass flow path 75.

[0031] The flow path switching valve 20 is configured to selectively switch the connection between a flow path upstream of the flow path switching valve 20 and a flow path downstream of the flow path switching valve 20 from any of the four states: state 1, state 2, state 3, and state 4. Thus, the flow path switching valve 20 switches the path of the cooling water circulation. The flow path switching valve 20 is driven, for example, by a stepper motor.

[0032] In the first state, the flow path switching valve 20 connects the first port P1 and the second port P2, blocks the first port P1 and the fourth port P4, connects the third port P3 and the fourth port P4, blocks the third port P3 and the second port P2, and shields the fifth port P5. Figure 1The connection state indicated by the solid line inside the flow path switching valve 20 is the first state. In the first state, the cooling water flow path is divided into two paths: one is the path that circulates through the cooler 17, the first flow path 71, the second flow path 72, the first water jacket 11 and the cooler flow path 76, and the other is the path that circulates through the fourth flow path 74, the radiator 30 and the third flow path 73.

[0033] In the second state, the flow path switching valve 20 blocks port 1 P1 and port 2 P2, connects port 1 P1 and port 4 P4, blocks port 3 P3 and port 4 P4, connects port 3 P3 and port 2 P2, and shields port 5 P5. Figure 1 The connection state indicated by a single-dot dash within the flow path switching valve 20 is the second state. In the second state, the cooling water flows only through the path of circulating through the cooler 17, the first flow path 71, the fourth flow path 74, the radiator 30, the third flow path 73, the second flow path 72, the first water jacket 11, and the cooler flow path 76.

[0034] In the third state, the flow path switching valve 20 blocks port 1 P1 and port 2 P2, connects port 1 P1 and port 4 P4, blocks port 3 P3 and port 4 P4, connects port 3 P3 and port 5 P5, and shields port 2 P2. In the third state, the cooling water flows only around the first water jacket 11 and circulates through the cooler 17, the first flow path 71, the fourth flow path 74, the radiator 30, the third flow path 73, and the bypass flow path 75.

[0035] In the fourth state, the flow path switching valve 20 blocks ports P1 and P2, and also blocks ports P1 and P4, while connecting ports P3 and P4, connecting ports P1 and P5, and shielding port P2. In the fourth state, the cooling water flow path is divided into two paths: one that bypasses the first water jacket 11 and circulates through the cooler 17, the first flow path 71, and the bypass flow path 75; and the other that circulates through the fourth flow path 74, the radiator 30, and the third flow path 73.

[0036] <Diagnostic Device 90>

[0037] The diagnostic device 90 receives a detection signal ×1 output from the first water temperature sensor 61, a detection signal ×2 output from the second water temperature sensor 62, and a detection signal ×3 output from the third water temperature sensor 63. The processing circuit 91 obtains the water temperature in each flow path based on the detection signals ×1, ×2, and ×3.

[0038] The processing circuit 91 controls the cooler 17 by outputting a command signal Y2 to the cooler 17. The storage device 92 stores the lower limit value LL of the possible values ​​of the second water temperature WT2 in the second state. For example, the storage device 92 can store the upper limit value UL of the possible values ​​of the second water temperature WT2 in the first state.

[0039] The processing circuit 91 controls the flow path switching valve 20 by outputting a control signal, Y1, indicating the valve position of the flow path switching valve 20. When the flow path switching valve 20 is in its normal state, it selectively switches the connection state to the state indicated by the control signal. However, due to wear of the stepper motor, the flow path switching valve 20 may sometimes fail to switch the path to the connection state indicated by the control signal, even when receiving the control signal normally. That is, the flow path switching valve 20 may sometimes malfunction and fail to operate normally even when receiving the control signal normally.

[0040] Diagnosis of flow path switching valve 20

[0041] The processing circuit 91 performs a series of processes to determine whether the flow path switching valve 20 is operating normally, when the flow path switching valve 20 sends a switching signal C1, indicating a switch to the cooling water circuit 80 connection state, as a command signal Y1 in its first state. This series of processes is executed by the processing circuit 91, for example, when a distributor or other diagnoses whether the flow path switching valve 20 is functioning correctly. Hereinafter, the step numbers of each process are indicated by numbers beginning with "S".

[0042] like Figure 2 As shown, if this series of processes begins, in process S10, the processing circuit 91 sends a cooling signal FC as a command signal Y2 to the cooler 17. Upon receiving the cooling signal FC, the cooler 17 begins cooling the cooling water. Then, the processing circuit 91 proceeds to process S11.

[0043] In the process of S11, the processing circuit 91 determines whether a predetermined time TE1 has elapsed. The predetermined time TE1 is predetermined, for example, based on the cooling capacity of the cooler 17 and the flow path length of the cooling water circuit 80. The predetermined time TE1 can be set, for example, as the time required from the time the cooler 17 starts operating in the second state until the water temperature measured by the first water temperature sensor 61, the second water temperature sensor 62, and the third water temperature sensor 63 stabilizes. The predetermined time TE1 can be determined in advance through experiments. If the predetermined time TE1 has not elapsed (S11: No), the processing circuit 91 repeats the process of S11. If the predetermined time TE1 has elapsed (S11: Yes), the processing circuit 91 proceeds to S12.

[0044] In the process of S12, the processing circuit 91 acquires the first water temperature PRWT1A, the second water temperature PRWT2A, and the third water temperature PRWT3A before the switch. The first water temperature PRWT1A before the switch is the first water temperature WT1 before the processing circuit 91 sends the switching signal C1 to the flow path switching valve 20 and the cooler 17 is in operation. The second water temperature PRWT2A before the switch is the second water temperature WT2 before the processing circuit 91 sends the switching signal C1 to the flow path switching valve 20 and the cooler 17 is in operation. The third water temperature PRWT3A before the switch is the third water temperature WT3 before the processing circuit 91 sends the switching signal C1 to the flow path switching valve 20 and the cooler 17 is in operation. After acquiring the first water temperature PRWT1A, the second water temperature PRWT2A, and the third water temperature PRWT3A before the switch, the processing circuit 91 proceeds to S13.

[0045] In process S13, processing circuit 91 sends switching signal C1 to flow path switching valve 20. Then, processing circuit 91 proceeds to process S14. In process S14, processing circuit 91 determines whether a predetermined time TE2 has elapsed. The predetermined time TE2 is predetermined, for example, based on the flow path length of cooling water circuit 80. The predetermined time TE2 can be set, for example, as the time required for the water temperature measured by the first water temperature sensor 61, the second water temperature sensor 62, and the third water temperature sensor 63 to stabilize after switching the connection state from the second state to the first state. The predetermined time TE2 can be determined in advance through experiments. If the predetermined time TE2 has not elapsed (S14: No), processing circuit 91 repeats process S14. If the predetermined time TE2 has elapsed (S14: Yes), processing circuit 91 proceeds to process S15.

[0046] In the process of S15, the processing circuit 91 acquires the first water temperature POWT1A and the second water temperature POWT2A after the switch. The first water temperature POWT1A after the switch is the first water temperature WT1 after a predetermined time TE2. The second water temperature POWT2A after the switch is the second water temperature WT2 after a predetermined time TE2. After acquiring the first water temperature POWT1A and the second water temperature POWT2A after the switch, the processing circuit 91 proceeds to S16.

[0047] In the S16 processing, the processing circuit 91 performs calculations on the first pre-switch temperature difference PRTD1A, the second post-switch temperature difference POTD2A, and the third pre-switch temperature difference PRTD3A. The first pre-switch temperature difference PRTD1A is the value obtained by subtracting the first pre-switch water temperature PRWT1A from the second pre-switch water temperature PRWT2A. The second post-switch temperature difference POTD2A is the value obtained by subtracting the first post-switch water temperature POWT1A from the second post-switch water temperature POWT2A. The third pre-switch temperature difference PRTD3A is the value obtained by subtracting the first pre-switch water temperature PRWT1A from the third pre-switch water temperature PRWT3A.

[0048] In the process of S16, the processing circuit 91 determines whether the following conditions (A1), (A2) and (A3) are met.

[0049] Condition (A1): The temperature difference PRTD1A before the first switch is greater than the predetermined value DA. The predetermined value DA is, for example, the upper limit UL of the possible values ​​of the second water temperature WT2 in the first state.

[0050] Condition (A2): After the second switch, the temperature difference POTD2A is below the predetermined value DA.

[0051] Condition (A3): The value obtained by subtracting the lower limit LL of the possible values ​​of the second water temperature WT2 in the second state from the temperature difference PRTD3A before the third switch is greater than the temperature difference POTD2A after the second switch.

[0052] In the process of S16, if the processing circuit 91 determines that all conditions (A1), (A2), and (A3) are met (S16: Yes), the process proceeds to S17. In the process of S17, the processing circuit 91 determines that the connection state of the cooling water circuit 80 has been switched to state 1, and determines that the flow path switching valve 20 is normally performing the action of switching the connection state of the cooling water circuit 80 to state 1. Then, the processing circuit 91 terminates. Figure 2 The series of processes shown.

[0053] In the process of S16, if the processing circuit 91 determines that at least one of the conditions (A1), (A2), and (A3) is not met (S16: No), the process proceeds to S18. In the process of S18, the processing circuit 91 retains its determination of whether the flow path switching valve 20 is operating normally. Then, the processing circuit 91 terminates. Figure 2 The series of processes shown.

[0054] When the temperature of the cooling water upstream of the flow path switching valve 20 before sending the switching signal C1 is set as the upstream water temperature PRUWT before the switch, the first water temperature PRWT1A before the switch is the upstream water temperature PRUWT before the switch. When the temperature of the cooling water downstream of the flow path switching valve 20 before sending the switching signal C1 is set as the downstream water temperature PRDWT before the switch, the second water temperature PRWT2A and the third water temperature PRWT3A before the switch are the downstream water temperatures PRDWT before the switch.

[0055] If the temperature of the cooling water upstream of the flow path switching valve 20 after a predetermined time TE2 elapsed from the sending of the switching signal C1 is set as the upstream water temperature POUWT after the switch, then the first water temperature POWT1A after the switch is the upstream water temperature POUWT after the switch. If the temperature of the cooling water downstream of the flow path switching valve 20 after a predetermined time TE2 elapsed from the sending of the switching signal C1 is set as the downstream water temperature PODWT after the switch, then the second water temperature POWT2A after the switch is the downstream water temperature PODWT after the switch.

[0056] When the difference between the upstream water temperature PRUWT and the downstream water temperature PRDWT before the switch is set as the pre-switch temperature difference PRTD, the first pre-switch temperature difference PRTD1A and the third pre-switch temperature difference PRTD3A are the pre-switch temperature difference PRTD. When the difference between the upstream water temperature POUWT and the downstream water temperature PODWT after the switch is set as the post-switch temperature difference POTD, the second post-switch temperature difference POTD2A is the post-switch temperature difference POTD. That is, the processing circuit 91 in... Figure 2 In the process of S16 shown, the flow path switching valve 20 is determined to be operating normally based on the fact that both the temperature difference PRTD before switching and the temperature difference POTD after switching meet the specified conditions.

[0057] <Function of the first implementation method>

[0058] In states 1, 2, 3, and 4, the connection state of the cooling water from cooler 17 flowing into the first water jacket 11 is states 1 and 2. Compared to state 2, the path from cooler 17 to the first water jacket 11 is shorter in state 1. Therefore, compared to state 2, state 1 makes it easier for the cooling water from cooler 17 to cool the battery cell 10A. Therefore, in order to diagnose a state where the battery cell 10A is easily cooled, it is necessary to determine whether the connection state of the flow path switching valve 20 has switched to state 1.

[0059] use Figure 3 The function of the first embodiment will be explained. Figure 3 Indicates in Figure 2The diagram illustrates the progression of water temperatures WT1, WT2, and WT3 during a series of processes, where the flow path switching valve 20 normally switches to state 1. Solid line L1 represents the progression of water temperature WT1. Solid line L2 represents the progression of water temperature WT2. Solid line L3 represents the progression of water temperature WT3. Time "T1" is the moment after a predetermined time TE1 has elapsed since the processing circuit 91 activated the cooler 17. Time "T2" is the moment when the processing circuit 91 sends the switching signal C1 to the flow path switching valve 20. Time "T3" is the moment after a predetermined time TE2 has elapsed from time "T2".

[0060] exist Figure 2 In the S12 process shown, the processing circuit 91 acquires the first water temperature PRWT1A, the second water temperature PRWT2A, and the third water temperature PRWT3A before the switch at time "T1". The first water temperature PRWT1A before the switch at time "T1" is "K1". The second water temperature PRWT2A before the switch at time "T1" is "K2B". The third water temperature PRWT3A before the switch at time "T1" is "K3". Figure 2 In the S15 process shown, the processing circuit 91 acquires the first water temperature POWT1A and the second water temperature POWT2A after the switch at time "T3". The first water temperature POWT1A after the switch at time "T3" is "K1". The second water temperature POWT2A after the switch at time "T3" is "K2A".

[0061] If the first water temperature WT1 and the second water temperature WT2 are close to each other before the switching signal C1 for switching to state 1 is sent, it cannot be determined that the connection state of the cooling water circuit 80 has become state 1 and that the first water temperature WT1 and the second water temperature WT2 are close to each other. Therefore, the processing circuit 91 uses the temperature difference PRTD1A before the first switch being greater than the predetermined value DA as the first condition (A1) for determining that the cooling water circuit 80 has switched to state 1.

[0062] like Figure 3 As shown, the temperature difference PRTD1A before the first switch at time "T1" is "K2B" - "K1". "K2B" - "K1" is greater than the predetermined value DA. Therefore, Figure 3 The change in water temperature shown satisfies condition (A1).

[0063] In the first state, cooling water flowing from cooler 17 flows into the first port P1 of flow path switching valve 20 after passing through the first flow path 71. Then, the cooling water flowing into the first port P1 flows out from the second port P2 and into the second flow path 72. Therefore, in the first state, the first water temperature WT1 and the second water temperature WT2 gradually become close to each other. Therefore, the processing circuit 91 uses the temperature difference POTD2A after the second switch being a predetermined value DA or below as the second condition (A2) for determining the connection state to switch to the first state.

[0064] like Figure 3 As shown, the temperature difference POTD2A after the second switch at time "T3" is "K2A" - "K1". "K2A" - "K1" is below the predetermined value DA. Therefore, Figure 3 The change in water temperature shown satisfies condition (A2).

[0065] Even if the temperature difference POTD2A after the second switch is below the predetermined value DA, the connection state after the switch may still be in the second state if the second water temperature POWT2A after the switch is within the range of the possible values ​​of the second water temperature WT2 in the second state. If the value obtained by subtracting the lower limit LL of the possible values ​​of the second water temperature WT2 in the second state from the temperature difference PRTD3A before the third switch is greater than the temperature difference POTD2A after the second switch, the second water temperature POWT2A after the switch becomes a temperature lower than the lower limit LL. Therefore, the processing circuit 91 uses the value obtained by subtracting the lower limit LL from the temperature difference PRTD3A before the third switch being greater than the temperature difference POTD2A after the second switch as the third condition (A3) for determining that the connection state has switched to the first state.

[0066] like Figure 3 As shown, the value DEF, obtained by subtracting the lower limit LL of the possible values ​​of the second water temperature WT2 in the second state from the temperature difference PRTD3A before the third switch, is greater than the temperature difference POTD2A after the second switch. Therefore, Figure 3 The temperature shift shown satisfies condition (A3).

[0067] <Effects of the first implementation method>

[0068] (1-1) The diagnostic device 90 can diagnose whether the connection state of the path in the cooling water circuit 80 can be normally switched to the first state by determining whether all three conditions (A1), (A2) and (A3) are met.

[0069] (1-2) A second water jacket 32, a third water jacket 37, and an oil cooler 40 are provided in the third flow path 73 of the cooling water circuit 80. In the second water jacket 32, heat exchange occurs between the on-board charger 31 and the cooling water. In the third water jacket 37, heat exchange occurs between the power control unit 36 ​​and the cooling water. In the oil cooler 40, heat exchange occurs between the lubricating oil and the cooling water.

[0070] In the cooling water circuit 80, which is in the second connection state, the cooling water cooled by the cooler 17 flows through the second water jacket 32, the third water jacket 37, and the oil cooler 40 before flowing into the first water jacket 11. At this time, the cooling water recovers heat from each on-board device. Therefore, the second water temperature WT2 in the second state is more likely to be higher than the first water temperature WT1. On the other hand, compared to the second state, the first state allows colder cooling water to flow into the first water jacket 11. The diagnostic device 90 can determine whether the flow path switching valve 20 can properly switch the connection state of the cooling water circuit 80 to the first state, which facilitates cooling of the battery cell 10A.

[0071] (1-3) If the cooling water circulation path is switched due to a change in the connection state, the temperature difference between the upstream and downstream of the flow path switching valve 20 changes. The diagnostic device 90 determines whether the pre-switching temperature difference PRTD before the switching signal C1 to switch to the established connection state is sent meets the specified conditions. The diagnostic device 90 also determines whether the post-switching temperature difference POTD after a predetermined time TE2 following the sending of the switching signal C1 to switch to the established connection state meets the specified conditions. That is, the diagnostic device 90 determines whether both the pre-switching temperature difference PRTD and the post-switching temperature difference POTD meet the specified conditions, unlike the case where the diagnostic device 90 determines whether the path is opened or closed, where it only determines whether the temperature difference decreases. By performing this determination, it is possible to determine whether the cooling water circulation path has switched to the established path. According to the diagnostic device 90, by using the information of the temperature difference before and after sending the switching signal C1 to determine the switch to the established connection state, it is possible to determine that the flow path switching valve 20 is operating normally.

[0072] (Second Implementation)

[0073] The following is for reference. Figure 4 and Figure 5 The diagnostic device for the flow path switching valve 20 of the second embodiment will be described. The diagnostic device 90 of this embodiment performs... Figure 4 The series of processes shown replace Figure 2 The process is shown. This series of processes is performed by the processing circuit 91, for example, when a distributor or other diagnoses whether the flow path switching valve 20 is functioning properly.

[0074] Diagnosis of flow path switching valve 20

[0075] like Figure 4 As shown, if this series of processes begins, in process S30, the processing circuit 91 acquires the first water temperature PRWT1B and the third water temperature PRWT3B before switching. The first water temperature PRWT1B before switching is the first water temperature WT1 before the processing circuit 91 sends the switching signal C1 to the flow path switching valve 20 and before the cooler 17 is in operation. The third water temperature PRWT3B before switching is the third water temperature WT3 before the processing circuit 91 sends the switching signal C1 to the flow path switching valve 20 and before the cooler 17 is in operation. After acquiring the first water temperature PRWT1B and the third water temperature PRWT3B before switching, the processing circuit 91 proceeds to process S31.

[0076] In process S31, processing circuit 91 sends switching signal C1 to flow path switching valve 20. Then, processing circuit 91 proceeds to process S32.

[0077] In the process of S32, the processing circuit 91 sends a cooling signal FC to the cooler 17. Upon receiving the cooling signal FC, the cooler 17 begins cooling the cooling water. Then, the processing circuit 91 proceeds to S33.

[0078] In the process of S33, the processing circuit 91 determines whether a predetermined time TE3 has elapsed since the cooling signal FC was sent. The predetermined time TE3 is predetermined, for example, based on the cooling capacity of the cooler 17 and the flow path length of the cooling water circuit 80. The predetermined time TE3 can be set, for example, as the time required from the time the cooler 17 is started in the first state until the water temperature measured by the first water temperature sensor 61, the second water temperature sensor 62, and the third water temperature sensor 63 stabilizes. The predetermined time TE3 can be determined in advance through experiments. If the predetermined time TE3 has not elapsed (S33: No), the processing circuit 91 repeats the process of S33. If the predetermined time TE3 has elapsed (S33: Yes), the processing circuit 91 proceeds to S34.

[0079] In the process of S34, the processing circuit 91 acquires the first water temperature CWT1, the second water temperature CWT2, and the third water temperature CWT3 after cooling. The first water temperature CWT1 after cooling is the first water temperature WT1 after a predetermined time TE3. The second water temperature CWT2 after cooling is the second water temperature WT2 after a predetermined time TE3. The third water temperature CWT3 after cooling is the third water temperature WT3 after a predetermined time TE3. After acquiring the first water temperature CWT1, the second water temperature CWT2, and the third water temperature CWT3 after cooling, the processing circuit 91 proceeds to S35.

[0080] In the S35 processing, the processing circuit 91 performs calculations on the temperature difference PRTD1B before the first switch, the temperature difference POTD2B after the second switch, and the temperature difference POTD3B after the third switch. The temperature difference PRTD1B before the first switch is obtained by subtracting the temperature PRWT1B before the first switch from the temperature PRWT3B before the third switch. The temperature difference POTD2B after the second switch is obtained by subtracting the temperature CWT1 after the first switch from the temperature CWT2 after cooling. The temperature difference POTD3B after the third switch is obtained by subtracting the temperature CWT1 after the first switch from the temperature CWT3 after cooling.

[0081] In the processing of S35, the processing circuit 91 determines whether the following conditions (B1), (B2) and (B3) are met.

[0082] Condition (B1): The temperature difference PRTD1B before the first switch is less than the predetermined first value DB1. The predetermined first value DB1 is determined in advance through experiments.

[0083] Condition (B2): After the second switch, the temperature difference POTD2B is less than the pre-defined second predetermined value DB2. The second predetermined value DB2 is determined in advance through experiments. Condition (B3): After the third switch, the temperature difference PRTD3B is greater than the pre-defined third predetermined value DB3. The third predetermined value DB3 is determined in advance through experiments.

[0084] In the process of S35, if the processing circuit 91 determines that all conditions (B1), (B2), and (B3) are met (S35: Yes), the process proceeds to S36. In the process of S36, if the processing circuit 91 determines that the connection state of the cooling water circuit 80 has been switched to state 1 and that the flow path switching valve 20 is operating normally, then the processing circuit 91 terminates. Figure 4 The series of processes shown.

[0085] In the process of S35, if the processing circuit 91 determines that at least one of the conditions (B1), (B2), and (B3) is not met (S35: No), the process proceeds to S37. In the process of S37, the processing circuit 91 retains its determination of whether the flow path switching valve 20 is operating normally. Then, the processing circuit 91 terminates. Figure 4 The series of processes shown.

[0086] Before switching, the first water temperature PRWT1B is the upstream water temperature PRUWT. Before switching, the third water temperature PRWT3B is the downstream water temperature PRDWT. After cooling, the first water temperature CWT1 is the upstream water temperature POUWT. After cooling, the second and third water temperatures CWT2 and CWT3 are the downstream water temperatures PODWT. The first temperature difference before switching PRTD1B is the temperature difference PRTD before switching. The second and third temperature differences after switching POTD2B and POTD3B are the temperature differences after switching POTD. That is, in the processing of S35, the processing circuit 91 determines that the flow path switching valve 20 is operating normally based on the fact that both the temperature difference PRTD before switching and the temperature difference POTD after switching meet the respective specified conditions.

[0087] <Function of the second implementation method>

[0088] use Figure 5 The function of the second embodiment will be explained. Figure 5 Indicates in Figure 4 The diagram illustrates the progression of water temperatures WT1, WT2, and WT3 during a series of processes, where the flow path switching valve 20 normally switches to state 1. Solid line L4 represents the progression of water temperature WT1. Solid line L5 represents the progression of water temperature WT2. Solid line L6 represents the progression of water temperature WT3. Time "T4" is the moment when the processing circuit 91 sends the cooling signal FC to the cooler 17. Time "T5" is the moment when a predetermined time TE3 has elapsed after the processing circuit 91 sends the cooling signal FC.

[0089] exist Figure 4 In the S30 process shown, the processing circuit 91 acquires the first water temperature PRWT1B and the third water temperature PRWT3B before the switch. The first water temperature PRWT1B before the switch is "K4BF". The third water temperature PRWT3B before the switch is "K6". Figure 4 In the S34 process shown, the processing circuit 91 acquires the first cooled water temperature CWT1, the second cooled water temperature CWT2, and the third cooled water temperature CWT3 at time "T5". The first cooled water temperature CWT1 at time "T5" is "K4AF". The second cooled water temperature CWT2 at time "T5" is "K5". The third cooled water temperature CWT3 at time "T5" is "K6".

[0090] If there is a difference between the first water temperature WT1 and the third water temperature WT3 before the cooler 17 starts operating, it cannot be determined whether the difference between the first water temperature WT1 and the third water temperature WT3 after the cooler 17 starts operating is a result of the cooling water being cooled by the cooler 17. The value obtained by subtracting the first water temperature PRWT1B before switching from the third water temperature PRWT3B before switching is the first temperature difference PRTD1B before switching. The processing circuit 91 uses the first temperature difference PRTD1B before switching being less than a predetermined first value DB1 as the first condition (B1) for determining that the cooling water circuit 80 is in the first state.

[0091] like Figure 5 As shown, the temperature difference PRTD1B before the first switch is "K6" - "K4BF". "K6" - "K4BF" is less than the first predetermined value DB1. Therefore, Figure 5 The change in water temperature shown satisfies condition (B1).

[0092] In the second state, the cooling water cooled by the cooler 17 passes through the flow path switching valve 20, then through the fourth flow path 74, radiator 30, radiator flow path 79, and third flow path 73, before flowing back into the flow path switching valve 20 and finally into the second flow path 72. Conversely, in the first state, the cooling water cooled by the cooler 17, after passing through the flow path switching valve 20, does not flow into the fourth flow path 74, but only into the second flow path 72. Therefore, the difference between the first water temperature WT1 and the second water temperature WT2 when the cooler 17 is operating is smaller in the first state than in the second state. The value obtained by subtracting the first water temperature CWT1 after cooling from the second water temperature CWT2 after cooling is the second switching temperature difference POTD2B. The processing circuit 91 uses the second switching temperature difference POTD2B being less than a predetermined second value DB2 as the second condition (B2) for determining that the cooling water circuit 80 is in the first state.

[0093] like Figure 5 As shown, the temperature difference POTD2B after the second switch at time "T5" is "K5" - "K4AF". "K5" - "K4AF" is below the second predetermined value DB2. Therefore, Figure 5 The temperature change shown satisfies condition (B2).

[0094] In the first state, the cooling water cooled by the cooler 17 does not flow into the third flow path 73. Therefore, in the first state, the temperature difference between the third water temperature WT3 and the first water temperature WT1 after the cooler 17 is running is greater than the temperature difference between the third water temperature WT3 and the first water temperature WT1 before the cooler 17 is running. The value obtained by subtracting the first water temperature CWT1 after cooling from the third water temperature CWT3 after cooling is the third switching temperature difference POTD3B. Therefore, the processing circuit 91 uses the third switching temperature difference POTD3B being greater than a predetermined third value DB3 as the third condition (B3) for determining that the cooling water circuit 80 is in the first state.

[0095] like Figure 5 As shown, the temperature difference POTD3B after the third switch at time "T5" is "K6" - "K4AF". "K6" - "K4AF" is greater than the predetermined value DB3. Therefore, Figure 5 The temperature shift shown satisfies condition (B3).

[0096] <Effects of the second implementation method>

[0097] In the second embodiment, in addition to the effects shown in (1-3) of the first embodiment, the following effects are also achieved.

[0098] (2-1) The diagnostic device 90 can diagnose whether the connection state of the flow path in the cooling water circuit 80 can be normally switched to the first state by determining whether all three conditions (B1), (B2) and (B3) are met.

[0099] Change Example

[0100] The following elements are among the elements that can be modified together with the above-described embodiments. The following modification examples can be combined and implemented within a technically compatible scope.

[0101] The diagnostic device 90 can be configured to perform simultaneous... Figure 2 The series of processes and Figure 4 The series of processes shown.

[0102] • The processing circuit 91 can be configured to perform a series of processes to determine whether the flow path switching valve 20 is operating normally, even while the vehicle is in motion.

[0103] For example, when the vehicle is in motion and a cooling signal FC is sent to the cooler 17, the processing circuit 91 acquires the first water temperature PRWT1A, the second water temperature PRWT2A, and the third water temperature PRWT3A before the switch, after a predetermined time TE1. The processing circuit 91 stores the acquired first water temperature PRWT1A, second water temperature PRWT2A, and third water temperature PRWT3A before the switch in the storage device 92. Then, when the processing circuit 91 performs the process of switching the cooling water circuit 80 to the first state while the cooler 17 is continuously operating, it acquires the first water temperature PRWT1A and the second water temperature PRWT2A after the switch after a predetermined time TE2. The processing circuit 91 uses the first water temperature PRWT1A, the second water temperature PRWT2A, and the third water temperature PRWT3A before the switch to calculate the first temperature difference PRTD1A and the third temperature difference PRTD3A before the switch. Processing circuit 91 uses the first water temperature POWT1A and the second water temperature POWT2A after the switch to calculate the second temperature difference POTD2A after the switch. Then, processing circuit 91 determines whether conditions (A1), (A2) and (A3) are met.

[0104] Processing circuit 91 acquires, for example, the first water temperature PRWT1B and the third water temperature PRWT3B before switching while the vehicle is in motion. Processing circuit 91 stores the acquired first water temperature PRWT1B and third water temperature PRWT3B before switching in storage device 92. Then, when a switching signal C1 is sent to flow path switching valve 20 due to the need to cool battery cell 10A, and a cooling signal FC is sent to cooler 17, the following processing is performed: After a predetermined time TE3 elapses after sending cooling signal FC, the first water temperature CWT1, the second water temperature CWT2, and the third water temperature CWT3 after cooling are acquired. Processing circuit 91 uses the first water temperature PRWT1B, the third water temperature PRWT3B before switching, the first water temperature CWT1 after cooling, the second water temperature CWT2 after cooling, and the third water temperature CWT3 after cooling to determine whether conditions (B1), (B2), and (B3) are met.

[0105] • The processing circuit 91 can be configured to perform the following when, for example, a user of a vehicle selects a diagnostic item for the flow path switching valve 20 displayed on the vehicle's display screen: Figure 2 The series of processes and Figure 4 The series of processes shown.

[0106] The vehicle is not limited to electric vehicles. Any vehicle may have a battery cell 10A housed within the battery pack 10. For example, the vehicle may be a plug-in hybrid electric vehicle (PHEV).

[0107] • The vehicle-mounted device equipped with the second water jacket 32 ​​is not limited to the vehicle charger 31. Any vehicle-mounted device equipped with the second water jacket 32 ​​that generates heat is acceptable.

[0108] • In the flow path from the outlet 34 of the second water jacket 32 ​​to the third port P3, the oil cooler 40 and the third water jacket 37 may not be provided.

[0109] Symbol Explanation

[0110] 20 - Flow path switching valve, 80 - Cooling water circuit, 90 - Diagnostic device, 91 - Processing circuit, C1 - Switching signal, PRUWT - Upstream water temperature before switching, PRDWT - Downstream water temperature before switching, PRTD - Temperature difference before switching, POUWT - Upstream water temperature after switching, PODWT - Downstream water temperature after switching, POTD - Temperature difference after switching.

Claims

1. A diagnostic device for a flow path switching valve, disposed in the cooling water circuit of a vehicle, selectively switching the connection state of the upstream flow path and the downstream flow path from multiple connection states to switch the cooling water circulation path, the diagnostic device for the flow path switching valve being characterized in that it comprises: The processing circuit sends a switching signal that causes the flow path switching valve to operate to the flow path switching valve. In the case where the water temperature of the cooling water upstream of the flow path switching valve before sending the switching signal is set as the upstream water temperature before switching, the water temperature of the cooling water downstream of the flow path switching valve before sending the switching signal is set as the downstream water temperature before switching, the water temperature of the cooling water upstream of the flow path switching valve after a predetermined time has elapsed since sending the switching signal is set as the upstream water temperature after switching, and the water temperature of the cooling water downstream of the flow path switching valve after the predetermined time has elapsed since sending the switching signal is set as the downstream water temperature after switching, When the processing circuit sends the switching signal to the flow path switching valve to switch the connection state to a predetermined connection state among the plurality of connection states, If the difference between the upstream water temperature before the switch and the downstream water temperature before the switch (i.e., the temperature difference before the switch) and the difference between the upstream water temperature after the switch and the downstream water temperature after the switch (i.e., the temperature difference after the switch) both meet the specified conditions, the flow path switching valve is determined to be operating normally.

2. The diagnostic device for the flow path switching valve according to claim 1, characterized in that, The cooling water circuit includes: a first water jacket for heat exchange between the battery cells housed in the battery pack and the cooling water; a cooler for cooling the cooling water; a radiator for cooling the cooling water; and a second water jacket for heat exchange between the on-board equipment that generates heat and the cooling water. A cooler flow path from the outlet of the first water jacket to the inlet of the cooler; a radiator flow path from the outlet of the radiator to the inlet of the second water jacket; a first flow path from the outlet of the cooler to the flow path switching valve; a second flow path from the flow path switching valve to the inlet of the first water jacket; a third flow path from the outlet of the second water jacket to the flow path switching valve; a fourth flow path from the flow path switching valve to the inlet of the radiator; and a bypass flow path from the flow path switching valve to the inlet of the cooler. A first water temperature sensor measures the temperature of the cooling water in the first flow path, i.e., the first water temperature; a second water temperature sensor measures the temperature of the cooling water in the second flow path, i.e., the second water temperature; and a third water temperature sensor measures the temperature of the cooling water in the third flow path, i.e., the third water temperature. The flow path switching valve includes: a first port connected to the first flow path; a second port connected to the second flow path; a third port connected to the third flow path; a fourth port connected to the fourth flow path; and a fifth port connected to the bypass flow path. The flow path switching valve is configured to switch the connection state to the following state: In the first state, it connects the first port and the second port, blocks the first port and the fourth port, connects the third port and the fourth port, blocks the third port and the second port, and shields the fifth port; In the second state, it blocks the first port and the second port, connects the first port and the fourth port, blocks the third port and the fourth port, connects the third port and the second port, and blocks the fifth port; In the third state, it blocks the first port and the second port, connects the first port and the fourth port, blocks the third port and the fourth port, connects the third port and the fifth port, and shields the second port; and In the fourth state, it blocks ports 1 and 2, and also blocks ports 1 and 4, while connecting ports 3 and 4; it also blocks ports 3 and 2, and connects ports 1 and 5. The predetermined connection state is the first state. The processing circuit performs the following processing: before sending the switching signal to the flow path switching valve to switch to the predetermined connection state, while the cooler is running, it acquires the first water temperature before switching (which is the first water temperature), the second water temperature before switching (which is the second water temperature before switching) before sending the switching signal to the flow path switching valve, and the third water temperature before switching (which is the third water temperature before switching) before sending the switching signal to the flow path switching valve. After acquiring the first water temperature, the second water temperature, and the third water temperature before the switch, the switching signal indicating the switch to the predetermined connection state is sent to the flow path switching valve; and After a predetermined time has elapsed since the switching signal indicating a switch to the predetermined connection state was sent, the first water temperature (i.e., the first water temperature after the switch) and the second water temperature (i.e., the second water temperature after the switch) are obtained after the predetermined time. The first pre-switch temperature difference, which is the value obtained by subtracting the first pre-switch water temperature from the second pre-switch water temperature, is greater than a predetermined value, and the second post-switch temperature difference, which is the value obtained by subtracting the first post-switch water temperature from the second post-switch water temperature, is less than or equal to the predetermined value. Furthermore, if the value obtained by subtracting the first water temperature before the switch from the third water temperature before the switch is taken as the third temperature difference before the switch, then the condition is that the value obtained by subtracting the lower limit of the possible values ​​of the second water temperature in the second state from the third temperature difference before the switch is greater than the second temperature difference after the switch. It is determined that the connection state of the cooling water circuit has been switched to the first state, and it is determined that the flow path switching valve is normally performing the action of switching the connection state of the cooling water circuit to the first state.

3. The diagnostic device for the flow path switching valve according to claim 2, characterized in that, The on-board device is an on-board charger that converts externally supplied AC power into DC power to charge the battery cell, and is adapted to a cooling water circuit. The cooling water circuit in the third flow path includes: an oil cooler that exchanges heat between the lubricating oil that lubricates the motor, which is the power source of the vehicle, and the cooling water; and a third water jacket that exchanges heat between the power control unit that controls the power of the motor and the cooling water.

4. The diagnostic device for the flow path switching valve according to claim 1, characterized in that, The cooling water circuit includes: a first water jacket for heat exchange between the battery cells housed in the battery pack and the cooling water; a cooler for cooling the cooling water; a radiator for cooling the cooling water; and a second water jacket for heat exchange between the on-board equipment that generates heat and the cooling water. A cooler flow path from the outlet of the first water jacket to the inlet of the cooler; a radiator flow path from the outlet of the radiator to the inlet of the second water jacket; a first flow path from the outlet of the cooler to the flow path switching valve; a second flow path from the flow path switching valve to the inlet of the first water jacket; a third flow path from the outlet of the second water jacket to the flow path switching valve; a fourth flow path from the flow path switching valve to the inlet of the radiator; and a bypass flow path from the flow path switching valve to the inlet of the cooler. A first water temperature sensor measures the temperature of the cooling water in the first flow path, i.e., the first water temperature; a second water temperature sensor measures the temperature of the cooling water in the second flow path, i.e., the second water temperature; and a third water temperature sensor measures the temperature of the cooling water in the third flow path, i.e., the third water temperature. The flow path switching valve includes: a first port connected to the first flow path; a second port connected to the second flow path; a third port connected to the third flow path; a fourth port connected to the fourth flow path; and a fifth port connected to the bypass flow path. The flow path switching valve is configured to switch the connection state to the following state: In the first state, it connects the first port and the second port, blocks the first port and the fourth port, connects the third port and the fourth port, blocks the third port and the second port, and shields the fifth port; In the second state, it blocks the first port and the second port, connects the first port and the fourth port, blocks the third port and the fourth port, connects the third port and the second port, and blocks the fifth port; In the third state, it blocks the first port and the second port, connects the first port and the fourth port, blocks the third port and the fourth port, connects the third port and the fifth port, and shields the second port; and In the fourth state, it blocks ports 1 and 2, and also blocks ports 1 and 4, while connecting ports 3 and 4; it also blocks ports 3 and 2, and connects ports 1 and 5. The predetermined connection state is the first state. The processing circuit performs the following processing: before sending the switching signal to the predetermined connection state to the flow path switching valve, it obtains the first water temperature before sending the switching signal to the flow path switching valve, i.e., the first water temperature before switching, and the third water temperature before sending the switching signal to the flow path switching valve, i.e., the third water temperature before switching. After obtaining the first water temperature before switching and the third water temperature before switching, the switching signal is sent to the flow path switching valve; After the switching signal is sent, a cooling signal that causes the cooler to operate is sent to the cooler. After a predetermined time has elapsed since the cooling signal was sent, the first water temperature (i.e., the first water temperature after cooling), the second water temperature (i.e., the second water temperature after cooling), and the third water temperature (i.e., the third water temperature after cooling) are obtained after the predetermined time. The condition is that the first pre-switch temperature difference (obtained by subtracting the first pre-switch temperature from the third pre-switch temperature) is less than a predetermined first value, the second post-switch temperature difference (obtained by subtracting the first post-cooling temperature from the second post-cooling temperature) is less than a predetermined second value, and the third post-switch temperature difference (obtained by subtracting the first post-cooling temperature from the third post-cooling temperature) is greater than a predetermined third value. It is determined that the connection state of the cooling water circuit has been switched to the first state, and it is determined that the flow path switching valve is normally performing the action of switching the connection state of the cooling water circuit to the first state.

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