Diagnostic device for flow path switching valves

Abstract

This invention provides a diagnostic device for a flow path switching valve that can determine if the flow path switching valve is operating normally by using information on the temperature difference before and after the transmission of a switching signal to determine that the valve has switched to the default connection state. [Solution] The diagnostic device includes a processing circuit that transmits a switching signal C1 to the flow path switching valve 20 to operate the flow path switching valve. The processing circuit determines that the flow path switching valve 20 is operating normally if the first pre-switching temperature difference PRTD1A is greater than a default value DA, the second post-switching temperature difference POTD2A is less than or equal to a default value DA, and the value obtained by subtracting the lower limit value LL of the possible values ​​of the second water temperature WT2 in the second state from the third pre-switching temperature difference PRTD3A is greater than the second post-switching temperature difference POTD2A (S16:YES). (S17)

Description

TECHNICAL FIELD

[0001] The present invention relates to a diagnostic device for a flow path switching valve.

BACKGROUND ART

[0002] Patent Document 1 discloses a switching valve failure determination device that determines whether a switching valve operates normally in an engine cooling water circuit. This device issues a valve opening request to the switching valve in order to determine whether the switching valve operates normally. In this device, after the valve opening request is issued to the switching valve, when the detected value of the water temperature sensor upstream of the switching valve and the detected value of the water temperature sensor downstream of the switching valve become substantially the same value, it is determined that the switching valve operates normally. This device determines that a failure has occurred when it cannot be determined that the switching valve is operating normally even after a predetermined period of time has elapsed.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0003]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] There is also a cooling water circuit provided with a flow path switching valve configured to be capable of switching the path through which cooling water circulates, instead of a switching valve that switches between a state where the path in the cooling water circuit is opened and closed to allow cooling water to flow and a state where the flow of cooling water is blocked. In this case, even before the connection state between the upstream flow path and the downstream flow path is switched by the flow path switching valve, the difference between the detected value of the water temperature sensor upstream of the flow path switching valve and the detected value of the water temperature sensor downstream of the flow path switching valve may possibly become a substantially identical value. In that case, the above-described switching valve failure determination device cannot determine whether the flow path switching valve is normal.

MEANS FOR SOLVING THE PROBLEMS

[0005] A diagnostic device for a flow path switching valve to solve the above problems is provided in the vehicle's cooling water circuit and selectively switches the connection state between the upstream flow path and the downstream flow path from a plurality of connection states to switch the path through which the cooling water circulates. The diagnostic device includes a processing circuit that transmits a switching signal to the flow path switching valve to operate the flow path switching valve. The water temperature of the cooling water upstream of the flow path switching valve before the switching signal is defined as the upstream water temperature before switching. The water temperature of the cooling water downstream of the flow path switching valve before the switching signal is defined 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 the switching signal was transmitted is defined as the upstream water temperature after switching. The water temperature of the cooling water downstream of the flow path switching valve after the predetermined time has elapsed since the switching signal was transmitted is defined as the downstream water temperature after switching. When the processing circuit transmits a switching signal to the flow path switching valve to switch the connection state to a predetermined connection state from among the plurality of connection states, it determines that the flow path switching valve is operating normally based on the fact that both the pre-switching temperature difference, which is the difference between the upstream water temperature before switching and the downstream water temperature before switching, and the post-switching temperature difference, which is the difference between the upstream water temperature after switching and the downstream water temperature after switching, each satisfy the conditions specified for each. [Effects of the Invention]

[0006] The diagnostic device described above can determine that the flow path switching valve is operating normally by using information on the temperature difference before and after the transmission of the switching signal to determine that it has switched to the default connection state. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing the configuration of the cooling water circuit of a vehicle equipped with the diagnostic device of the first embodiment. [Figure 2] Figure 2 is a flowchart showing the sequence of processes performed by the processing circuit in Figure 1 for diagnosing the flow path switching valve. [Figure 3]Figure 3 shows the conditions defined for the temperature difference before switching and the temperature difference after switching in the diagnostic device of the first embodiment. [Figure 4] Figure 4 is a flowchart showing the flow of a series of processes for diagnosing a flow path switching valve, which are performed by the processing circuit of the diagnostic device in the second embodiment. [Figure 5] Figure 5 shows the conditions defined for the temperature difference before switching and the temperature difference after switching in the diagnostic device of the second embodiment. [Modes for carrying out the invention]

[0008] (First Embodiment) The diagnostic device of the first embodiment will be described below with reference to Figures 1 to 3. <Regarding the thermal management system 1 installed in the vehicle> As shown in Figure 1, the vehicle comprises a battery pack 10 containing multiple battery cells 10A, and a drive motor 51 that uses the power stored in the multiple battery cells 10A. In Figure 1, the multiple battery cells 10A arranged inside the battery pack 10 are shown together enclosed by a dashed line. The drive motor 51 is the power source of the vehicle. The vehicle is an electric vehicle (Battery Electric Vehicle: BEV) that uses only the drive motor 51 as its power source.

[0009] The vehicle is equipped with a thermal management system 1. The thermal management system 1 is a system for maintaining multiple battery cells 10A at appropriate temperatures and for cooling multiple on-board equipment, including the drive motor 51. The thermal management system 1 comprises a cooling water circuit 80 and a diagnostic device 90. The flow path switching valve 20 is provided in the cooling water circuit 80. The diagnostic device 90 comprises a processing circuit 91 that executes a program and performs various processes, and a storage device 92 in which the program is stored. The processing circuit 91 includes a processor. The storage device 92 can store various data. Below, the configuration of the cooling water circuit 80 will be described first, followed by a description of the diagnosis of the flow path switching valve 20 by the diagnostic device 90.

[0010] <Cooling water circuit 80> The cooling water circuit 80 is configured for the circulation of cooling water. In Figure 1, the direction of the cooling water flow in the cooling water circuit 80 is indicated by the direction of the arrows. The cooling water is, for example, LLC (Long Life Coolant).

[0011] As shown in Figure 1, the cooling water circuit 80 includes a first water jacket 11. As shown by the dashed line in Figure 1, the first water jacket 11 is located inside the battery pack 10. Heat exchange takes place in the first water jacket 11 between the battery cells 10A housed in the battery pack 10 and the cooling water.

[0012] The cooling water circuit 80 includes a chiller 17 for cooling the cooling water. The chiller 17 is a water-cooled heat exchanger. The chiller 17 performs heat exchange between, for example, a refrigerant for air conditioning and the cooling water flowing through the cooling water circuit 80. The refrigerant for air conditioning is, for example, an HFC (Hydrofluorocarbon) refrigerant or an HFO (Hydrofluoroolefin) refrigerant.

[0013] 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 includes a second water jacket 32. As shown by the dashed line in Figure 1, the second water jacket 32 ​​is located inside the on-board charger 31. Heat exchange takes place between the on-board charger 31 and the cooling water in 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 AC power supplied from an external source into DC power to charge the battery cell 10A.

[0014] The cooling water circuit 80 includes an oil cooler 40 in which heat exchange takes place between the lubricating oil that lubricates the drive motor 51 and the cooling water. The lubricating oil circulates within the lubricating oil path 50, which is shown by the dashed line in Figure 1. The lubricating oil within the lubricating oil path 50 is circulated by the oil pump 52.

[0015] The cooling water circuit 80 includes a third water jacket 37. As shown by the dashed line in Figure 1, the third water jacket 37 is located inside the power control unit 36. Heat exchange takes place between the power control unit 36 ​​and the cooling water in 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 in-vehicle device that generates heat.

[0016] The cooling water circuit 80 includes a chiller passage 76, a radiator passage 79, a first passage 71, a second passage 72, a third passage 73, a fourth passage 74, and a bypass passage 75. The chiller flow path 76 is a flow path from the outlet 13 of the first water jacket 11 to the inlet 17A of the chiller 17. The chiller flow path 76 is equipped with a reserve tank 14, a water pump 15, and a water-to-water heat exchanger 16. The outlet 13 is connected to the reserve tank 14, which stores cooling water. The reserve tank 14 is connected to the water pump 15, which circulates the cooling water. The cooling water discharged from the water pump 15 passes through the water-to-water heat exchanger 16 and then flows into the inlet 17A. The water-to-water heat exchanger 16 is a water-cooled heat exchanger. The water-to-water heat exchanger 16 performs heat exchange between, for example, a heat transfer medium for air conditioning and the cooling water flowing through the cooling water circuit 80. The heat transfer medium for air conditioning is, for example, LLC (Long Life Coolant).

[0017] 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. The first flow path 71 is a flow path from the outlet 17B of the chiller 17 to the flow path switching valve 20. The second flow path 72 is a 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 a 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 provided in the order of the water pump 35, the third water jacket 37, and the oil cooler 40 from the upstream side to the downstream side. The fourth flow path 74 is a flow path from the flow path switching valve 20 to the inlet 30A of the radiator 30. The bypass flow path 75 is a flow path from the flow path switching valve 20 to the inlet 17A of the chiller 17. A reserve tank 14, a water pump 15, and a water-water heat exchanger 16 are provided in the bypass flow path 75.

[0018] 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 a first water temperature WT1 which is the temperature of the cooling water in the first flow path 71. The second water temperature sensor 62 measures a second water temperature WT2 which is the temperature of the cooling water in the second flow path 72. The third water temperature sensor 63 measures a third water temperature WT3 which is the temperature of the cooling water in the third flow path 73. The third water temperature sensor 63 measures, as the third water temperature WT3, the temperature of the cooling water flowing between the water pump 35 and the power control unit 36 in the third flow path 73.

[0019] <流路切替弁20> The flow path switching valve 20 includes 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.

[0020] The flow path switching valve 20 is configured to selectively switch the connection state between the flow path upstream of the flow path switching valve 20 and the flow path downstream of the flow path switching valve 20 to one of four connection states: a first state, a second state, a third state, and a fourth state. This allows the flow path switching valve 20 to switch the path through which the cooling water circulates. The flow path switching valve 20 is driven, for example, by a stepper motor.

[0021] 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. The connection state shown by the solid line within the flow path switching valve 20 in Figure 1 is the first state. In the first state, the paths through which the cooling water flows are divided into two paths: one that circulates through the chiller 17, the first flow path 71, the second flow path 72, the first water jacket 11, and the chiller flow path 76, and another that circulates through the fourth flow path 74, the radiator 30, and the third flow path 73.

[0022] In the second state, the flow path switching valve 20 blocks the first port P1 and the second port P2, connects the first port P1 and the fourth port P4, blocks the third port P3 and the fourth port P4, connects the third port P3 and the second port P2, and shields the fifth port P5. The connection state shown by the dashed line within the flow path switching valve 20 in Figure 1 is the second state. In the second state, the only path through which the cooling water flows is through the chiller 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 chiller flow path 76.

[0023] In the third state, the flow path switching valve 20 blocks the first port P1 and the second port P2, connects the first port P1 and the fourth port P4, blocks the third port P3 and the fourth port P4, connects the third port P3 and the fifth port P5, and shields the second port P2. In the third state, the only path through which the cooling water flows is one that bypasses the first water jacket 11 and circulates through the chiller 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.

[0024] In the fourth state, the flow path switching valve 20 blocks 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, connects the first port P1 and the fifth port P5, and shields the second port P2. In the fourth state, the path through which the cooling water flows is divided into two paths: one that bypasses the first water jacket 11 and circulates through the chiller 17, the first flow path 71, and the bypass flow path 75, and another that circulates through the fourth flow path 74, the radiator 30, and the third flow path 73.

[0025] <Diagnostic device 90> The diagnostic device 90 receives detection signals X1 output from the first water temperature sensor 61, detection signals X2 output from the second water temperature sensor 62, and detection signals X3 output from the third water temperature sensor 63. The processing circuit 91 acquires the water temperature in each flow path based on detection signals X1, X2, and X3.

[0026] The processing circuit 91 controls the chiller 17 by outputting a command signal Y2 to the chiller 17. The memory device 92 stores the lower limit LL of the possible values ​​of the second water temperature WT2 in the second state. For example, the memory device 92 may also store the upper limit UL of the possible values ​​of the second water temperature WT2 in the first state.

[0027] The processing circuit 91 controls the flow path switching valve 20 by outputting a control signal, Y1, to the flow path switching valve 20, which instructs the valve position of the flow path switching valve 20. When the flow path switching valve 20 is in a normal state, the flow path switching valve 20 selectively switches its connection state to the connection state instructed by the control signal. In some cases, the flow path switching valve 20 may not be able to switch the path to the connection state instructed by the control signal, even though it is receiving the control signal normally, for example, due to wear of the stepper motor. In other words, the flow path switching valve 20 may experience a malfunction that prevents it from operating normally, even though it is receiving the control signal normally.

[0028] <Diagnosis of the flow path switching valve 20> 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 transmits a switching signal C1 as a command signal Y1 to switch the connection state of the cooling water circuit 80 to the first state among multiple connection states. This series of processes is executed by the processing circuit 91, for example, when a dealer diagnoses whether the flow path switching valve 20 is functioning normally. In the following, the step number of each process is represented by a number preceded by "S".

[0029] As shown in Figure 2, when this series of processes is started, in process S10, the processing circuit 91 transmits the cooling signal FC as a command signal Y2 to the chiller 17. Upon receiving the cooling signal FC, the chiller 17 starts cooling the cooling water. After that, the processing circuit 91 proceeds to process S11.

[0030] In the process of S11, the processing circuit 91 determines whether a predetermined time TE1 has elapsed. The predetermined time TE1 is predetermined based on, for example, the cooling capacity of the chiller 17 and the flow path length of the cooling water circuit 80. The predetermined time TE1 may also be, for example, the time taken in the second state from the time the chiller 17 is activated 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 may also be determined experimentally in advance. If the predetermined time TE1 has not elapsed (S11: NO), the processing circuit 91 repeatedly executes the process of S11. If the predetermined time TE1 has elapsed (S11: YES), the processing circuit 91 proceeds to the process of S12.

[0031] In the S12 process, the processing circuit 91 acquires the first water temperature PRWT1A before switching, the second water temperature PRWT2A before switching, and the third water temperature PRWT3A before switching. The first water temperature PRWT1A before switching is the first water temperature WT1 before the processing circuit 91 transmits the switching signal C1 to the flow path switching valve 20 and when the chiller 17 is operating. The second water temperature PRWT2A before switching is the second water temperature WT2 before the processing circuit 91 transmits the switching signal C1 to the flow path switching valve 20 and when the chiller 17 is operating. The third water temperature PRWT3A before switching is the third water temperature WT3 before the processing circuit 91 transmits the switching signal C1 to the flow path switching valve 20 and when the chiller 17 is operating. After obtaining the first water temperature PRWT1A, the second water temperature PRWT2A, and the third water temperature PRWT3A before switching, the processing circuit 91 proceeds to S13.

[0032] In the process of S13, the processing circuit 91 transmits a switching signal C1 to the flow path switching valve 20. After that, the processing circuit 91 proceeds to the process of S14. In the process of S14, the 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 the cooling water circuit 80. The predetermined time TE2 may also be, for example, the time it takes 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 when the connection state is switched from the second state to the first state. The predetermined time TE2 may also be determined experimentally in advance. If the predetermined time TE2 has not elapsed (S14: NO), the processing circuit 91 repeatedly executes the process of S14. If the predetermined time TE2 has elapsed (S14: YES), the processing circuit 91 proceeds to the process of S15.

[0033] In the S15 process, the processing circuit 91 obtains the first water temperature POWT1A and the second water temperature POWT2A after switching. The first water temperature POWT1A after switching is the first water temperature WT1 after a predetermined time TE2 has elapsed. The second water temperature POWT2A after switching is the second water temperature WT2 after a predetermined time TE2 has elapsed. After obtaining the first water temperature POWT1A and the second water temperature POWT2A after switching, the processing circuit 91 proceeds to the S16 process.

[0034] In the S16 process, the processing circuit 91 calculates the first pre-switching temperature difference PRTD1A, the second post-switching temperature difference POTD2A, and the third pre-switching temperature difference PRTD3A. The first pre-switching temperature difference PRTD1A is the value obtained by subtracting the first water temperature PRWT1A before switching from the second water temperature PRWT2A before switching. The second post-switching temperature difference POTD2A is the value obtained by subtracting the first water temperature POWT1A after switching from the second water temperature POWT2A after switching. The third pre-switching temperature difference PRTD3A is the value obtained by subtracting the first water temperature PRWT1A before switching from the third water temperature PRWT3A before switching.

[0035] In the process of S16, the processing circuit 91 determines whether the following conditions (A1), (A2), and (A3) are met. Condition (A1): The temperature difference PRTD1A before the first switchover is greater than a predetermined default value DA. The default value DA is, for example, the upper limit UL of the possible values ​​of the second water temperature WT2 in the first state.

[0036] Condition (A2): The temperature difference POTD2A after the second switchover is less than or equal to the default value DA. Condition (A3): The difference between the temperature difference PRTD3A before the third switching state and the lower limit LL of the possible values ​​of the second water temperature WT2 in the second state is greater than the temperature difference POTD2A after the second switching state.

[0037] If the processing circuit 91 determines in the S16 process that all conditions (A1), (A2), and (A3) are met (S16: YES), it proceeds to the S17 process. In the S17 process, the processing circuit 91 determines that the connection state of the cooling water circuit 80 has been switched to the first state, and that the flow path switching valve 20 is performing normal operation to switch the connection state of the cooling water circuit 80 to the first state. After that, the processing circuit 91 completes the series of processes shown in Figure 2.

[0038] If the processing circuit 91 determines in the S16 process that at least one of conditions (A1), (A2), and (A3) is not met (S16: NO), it proceeds to the S18 process. In the S18 process, the processing circuit 91 suspends the determination of whether the flow path switching valve 20 is operating normally. After that, the processing circuit 91 terminates the series of processes shown in Figure 2.

[0039] If the temperature of the cooling water upstream of the flow path switching valve 20 before the switching signal C1 is transmitted is defined as the upstream water temperature PRUWT before switching, then the first water temperature PRWT1A before switching is the upstream water temperature PRUWT before switching. If the temperature of the cooling water downstream of the flow path switching valve 20 before the switching signal C1 is transmitted is defined as the downstream water temperature PRDWT before switching, then the second water temperature PRWT2A before switching and the third water temperature PRWT3A before switching are the downstream water temperature PRDWT before switching.

[0040] If the water temperature of the cooling water upstream of the flow path switching valve 20 after a predetermined time TE2 has elapsed since the switching signal C1 was transmitted is defined as the upstream water temperature POUWT after switching, then the first water temperature POWT1A after switching is the upstream water temperature POUWT after switching. If the water temperature of the cooling water downstream of the flow path switching valve 20 after a predetermined time TE2 has elapsed since the switching signal C1 was transmitted is defined as the downstream water temperature PODWT after switching, then the second water temperature POWT2A after switching is the downstream water temperature PODWT after switching.

[0041] If the difference between the upstream water temperature PRUWT before switching and the downstream water temperature PRDWT before switching is defined as the pre-switching temperature difference PRTD, then the first pre-switching temperature difference PRTD1A and the third pre-switching temperature difference PRTD3A are both the pre-switching temperature difference PRTD. If the difference between the upstream water temperature POUWT after switching and the downstream water temperature PODWT after switching is defined as the post-switching temperature difference POTD, then the second post-switching temperature difference POTD2A is also the post-switching temperature difference POTD. In other words, in the process of S16 shown in Figure 2, the processing circuit 91 determines that the flow path switching valve 20 is operating normally based on the fact that both the pre-switching temperature difference PRTD and the post-switching temperature difference POTD satisfy the conditions defined for each.

[0042] <Operation of the First Embodiment> Of the first, second, third, and fourth states, the connection states in which the cooling water cooled by the chiller 17 flows to the first water jacket 11 are the first and second states. The path from the chiller 17 to the first water jacket 11 is shorter in the first state than in the second state. Therefore, the battery cell 10A is more easily cooled by the cooling water cooled by the chiller 17 in the first state than in the second state. For this reason, in order to diagnose whether the battery cell 10A is in a state that is easy to cool, it is necessary to determine whether the connection state of the flow path switching valve 20 can be switched to the first state.

[0043] The operation of the first embodiment will be explained using Figure 3. Figure 3 shows the changes in the first water temperature WT1, the second water temperature WT2, and the third water temperature WT3 when the flow path switching valve 20 is successfully switched to the first state in the series of processes shown in Figure 2. The solid line L1 shows the change in the first water temperature WT1. The solid line L2 shows the change in the second water temperature WT2. The solid line L3 shows the change in the third water temperature WT3. Time "T1" is the time when a predetermined time TE1 has elapsed since the processing circuit 91 activated the chiller 17. Time "T2" is the time when the processing circuit 91 transmitted the switching signal C1 to the flow path switching valve 20. Time "T3" is the time when a predetermined time TE2 has elapsed since time "T2".

[0044] In the process of S12 shown in Figure 2, the processing circuit 91 acquires the first water temperature PRWT1A before switching, the second water temperature PRWT2A before switching, and the third water temperature PRWT3A before switching at time "T1". The first water temperature PRWT1A before switching at time "T1" is "K1". The second water temperature PRWT2A before switching at time "T1" is "K2B". The third water temperature PRWT3A before switching at time "T1" is "K3". In the process of S15 shown in Figure 2, the processing circuit 91 acquires the first water temperature POWT1A after switching and the second water temperature POWT2A after switching at time "T3". The first water temperature POWT1A after switching at time "T3" is "K1". The second water temperature POWT2A after switching at time "T3" is "K2A".

[0045] If the first water temperature WT1 and the second water temperature WT2 are close in value before the switching signal C1 is sent to switch the connection state to the first state, it cannot be determined that the connection state of the cooling water circuit 80 has become the first state, causing the first water temperature WT1 and the second water temperature WT2 to be close in value. Therefore, the processing circuit 91 uses the first condition (A1) for determining that the cooling water circuit 80 has been switched to the first state as the first condition in which the temperature difference PRTD1A before the first switching is greater than the default value DA.

[0046] As shown in Figure 3, the temperature difference PRTD1A before the first switchover at time "T1" is "K3" - "K1". "K3" - "K1" is greater than the default value DA. Therefore, the water temperature change shown in Figure 3 satisfies condition (A1).

[0047] In the first state, the cooling water flowing out from the chiller 17 passes through the first flow path 71 and then flows into the first port P1 of the flow path switching valve 20. Subsequently, the cooling water that has flowed 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 in value. Thus, the processing circuit 91 uses the fact that the temperature difference POTD2A after the second switching is less than or equal to a predetermined value DA as the second condition (A2) for determining that the connection state has been switched to the first state.

[0048] As shown in Figure 3, the temperature difference POTD2A after the second switchover at time "T3" is "K2A" - "K1". "K2A" - "K1" is less than or equal to the default value DA. Therefore, the water temperature change shown in Figure 3 satisfies condition (A2).

[0049] Even if the second post-switching temperature difference POTD2A is less than or equal to the default value DA, if the second water temperature POWT2A after switching is within the range of values ​​that the second water temperature WT2 in the second state can take, there remains a possibility that the connection state after switching is the second state. If the value obtained by subtracting the lower limit value LL of the values ​​that the second water temperature WT2 in the second state can take from the third pre-switching temperature difference PRTD3A is greater than the second post-switching temperature difference POTD2A, then the second water temperature POWT2A after switching will be lower than the lower limit value LL. Therefore, the processing circuit 91 uses as the third condition (A3) for determining that the connection state has been switched to the first state that the value obtained by subtracting the lower limit value LL from the third pre-switching temperature difference PRTD3A is greater than the second post-switching temperature difference POTD2A.

[0050] As shown in Figure 3, 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 switching, is greater than the temperature difference POTD2A after the second switching. Therefore, the temperature transition shown in Figure 3 satisfies condition (A3).

[0051] <Effects of the First Embodiment> (1-1) The diagnostic device 90 can diagnose whether the connection state of the path in the cooling water circuit 80 has been successfully switched to the first state by determining whether all conditions (A1), (A2), and (A3) are met.

[0052] (1-2) The third flow path 73 of the cooling water circuit 80 is provided with a second water jacket 32, a third water jacket 37, and an oil cooler 40. Heat exchange takes place between the onboard charger 31 and the cooling water in the second water jacket 32. Heat exchange takes place between the power control unit 36 ​​and the cooling water in the third water jacket 37. Heat exchange takes place between the lubricating oil and the cooling water in the oil cooler 40.

[0053] In the cooling water circuit 80, which is in the second state, the cooling water cooled by the chiller 17 passes through the second water jacket 32, the third water jacket 37, and the oil cooler 40 before flowing into the first water jacket 11. During this process, the cooling water recovers heat from each on-board component. Therefore, the second water temperature WT2 in the second state tends to be higher than the first water temperature WT1. On the other hand, the first state allows cooler cooling water to flow into the first water jacket 11 compared to the second state. The diagnostic device 90 can determine whether the flow path switching valve 20 can successfully switch the connection state of the cooling water circuit 80 to the first state, which is more suitable for cooling the battery cell 10A.

[0054] (1-3) When the connection state is switched and the path through which the cooling water circulates is switched, a change occurs in the temperature difference between the upstream and downstream of the flow path switching valve 20. The diagnostic device 90 determines whether the pre-switching temperature difference PRTD, before transmitting the switching signal C1 to switch to the default connection state, satisfies the specified conditions. The diagnostic device 90 also determines whether the post-switching temperature difference POTD, after a specified time TE2 has elapsed since transmitting the switching signal C1 to switch to the default connection state, satisfies the specified conditions. In other words, the diagnostic device 90 does not just determine whether the temperature difference has decreased, as in the case of simply determining whether the path is open or closed, but also determines whether both the pre-switching temperature difference PRTD and the post-switching temperature difference POTD satisfy the specified conditions. By performing such a determination, it becomes possible to determine whether the path through which the cooling water circulates has been switched to the default path. According to the diagnostic device 90, by using the temperature difference information before and after transmitting the switching signal C1 to determine that the connection state has been switched, it is possible to determine that the flow path switching valve 20 is operating normally.

[0055] (Second Embodiment) The diagnostic device for the flow path switching valve 20 of the second embodiment will now be described with reference to Figures 4 and 5. The diagnostic device 90 of this embodiment performs a series of processes shown in Figure 4 instead of the process shown in Figure 2. This series of processes is performed by the processing circuit 91 when diagnosing, for example, whether the flow path switching valve 20 is functioning correctly at a dealership.

[0056] <Diagnosis of the flow path switching valve 20> As shown in Figure 4, when this series of processes is started, in process S30, the processing circuit 91 acquires the pre-switching first water temperature PRWT1B and the pre-switching third water temperature PRWT3B. The pre-switching first water temperature PRWT1B is the first water temperature WT1 before the processing circuit 91 sends the switching signal C1 to the flow path switching valve 20 and when the chiller 17 is not operating. The pre-switching third water temperature PRWT3B is the third water temperature WT3 before the processing circuit 91 sends the switching signal C1 to the flow path switching valve 20 and when the chiller 17 is not operating. After acquiring the pre-switching first water temperature PRWT1B and the pre-switching third water temperature PRWT3B, the processing circuit 91 proceeds to process S31.

[0057] In the process of S31, the processing circuit 91 transmits a switching signal C1 to the flow path switching valve 20. After that, the processing circuit 91 proceeds to process S32. In the process of S32, the processing circuit 91 transmits a cooling signal FC to the chiller 17. Upon receiving the cooling signal FC, the chiller 17 begins to cool the cooling water. After that, the processing circuit 91 proceeds to process S33.

[0058] In the process of S33, the processing circuit 91 determines whether a predetermined time TE3 has elapsed since the cooling signal FC was transmitted. The predetermined time TE3 is predetermined based on, for example, the cooling capacity of the chiller 17 and the flow path length of the cooling water circuit 80. The predetermined time TE3 may also be, for example, the time it takes from the time the chiller 17 is activated 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 may also be determined experimentally in advance. If the predetermined time TE3 has not elapsed (S33: NO), the processing circuit 91 repeatedly executes the process of S33. If the predetermined time TE3 has elapsed (S33: YES), the processing circuit 91 proceeds to the process of S34.

[0059] In the process of S34, the processing circuit 91 obtains the first water temperature CWT1, the second water temperature CWT2, and the third water temperature CWT3 after cooling. The first water temperature CWT1 is the first water temperature WT1 after a predetermined time TE3 has elapsed. The second water temperature CWT2 is the second water temperature WT2 after a predetermined time TE3 has elapsed. The third water temperature CWT3 is the third water temperature WT3 after a predetermined time TE3 has elapsed. After obtaining 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.

[0060] In the S35 process, the processing circuit 91 calculates the first pre-switching temperature difference PRTD1B, the second post-switching temperature difference POTD2B, and the third post-switching temperature difference POTD3B. The first pre-switching temperature difference PRTD1B is the value obtained by subtracting the first water temperature PRWT1B before switching from the third water temperature PRWT3B before switching. The second post-switching temperature difference POTD2B is the value obtained by subtracting the first water temperature CWT1 after cooling from the second water temperature CWT2 after cooling. The third post-switching temperature difference POTD3B is the value obtained by subtracting the first water temperature CWT1 after cooling from the third water temperature CWT3 after cooling.

[0061] In the process of S35, the processing circuit 91 determines whether the following conditions (B1), (B2), and (B3) are met. Condition (B1): The temperature difference PRTD1B before the first switchover is less than the predetermined first default value DB1. The first default value DB1 has been determined experimentally in advance.

[0062] Condition (B2): The temperature difference POTD2B after the second switchover is less than the predetermined second default value DB2. The second default value DB2 has been determined experimentally in advance. Condition (B3): The temperature difference PRTD3B after the third switchover is greater than the predetermined third default value DB3. The third default value DB3 has been determined experimentally in advance.

[0063] If the processing circuit 91 determines in the S35 process that all conditions (B1), (B2), and (B3) are met (S35: YES), it proceeds to the S36 process. In the S36 process, the processing circuit 91 determines that the connection state of the cooling water circuit 80 has been switched to the first state and that the flow path switching valve 20 is operating normally. After that, the processing circuit 91 completes the series of processes shown in Figure 4.

[0064] If the processing circuit 91 determines in the S35 process that at least one of conditions (B1), (B2), and (B3) is not met (S35: NO), it proceeds to the S37 process. In the S37 process, the processing circuit 91 suspends the determination of whether the flow path switching valve 20 is operating normally. After that, the processing circuit 91 terminates the series of processes shown in Figure 4.

[0065] The first water temperature PRWT1B before switching is the upstream water temperature PRUWT before switching. The third water temperature PRWT3B before switching is the downstream water temperature PRDWT before switching. The first water temperature CWT1 after cooling is the upstream water temperature POUWT after switching. The second water temperature CWT2 and the third water temperature CWT3 after cooling are the downstream water temperature PODWT after switching. The first temperature difference PRTD1B before switching is the temperature difference PRTD before switching. The second temperature difference POTD2B after switching and the third temperature difference POTD3B after switching are the temperature difference POTD after switching. In other words, the processing circuit 91 determines that the flow path switching valve 20 is operating normally based on the fact that in the processing of S35, both the temperature difference PRTD before switching and the temperature difference POTD after switching satisfy the conditions specified for each.

[0066] <Operation of the second embodiment> The operation of the second embodiment will be explained using Figure 5. Figure 5 shows the changes in the first water temperature WT1, the second water temperature WT2, and the third water temperature WT3 when the flow path switching valve 20 is successfully switched to the first state in the series of processes shown in Figure 4. The solid line L4 shows the change in the first water temperature WT1. The solid line L5 shows the change in the second water temperature WT2. The solid line L6 shows the change in the third water temperature WT3. Time "T4" is the time when the processing circuit 91 transmits the cooling signal FC to the chiller 17. Time "T5" is the time when a predetermined time TE3 has elapsed since the processing circuit 91 transmitted the cooling signal FC.

[0067] In the process of S30 shown in Figure 4, the processing circuit 91 acquires the first water temperature PRWT1B before switching and the third water temperature PRWT3B before switching. The first water temperature PRWT1B before switching is "K4BF". The third water temperature PRWT3B before switching is "K6". In the process of S34 shown in Figure 4, the processing circuit 91 acquires the first water temperature CWT1 after cooling, the second water temperature CWT2 after cooling, and the third water temperature CWT3 after cooling at time "T5". The first water temperature CWT1 after cooling at time "T5" is "K4AF". The second water temperature CWT2 after cooling at time "T5" is "K5". The third water temperature CWT3 after cooling at time "T5" is "K6".

[0068] If there is a difference between the first water temperature WT1 and the third water temperature WT3 before the chiller 17 starts operating, it is not possible to determine whether the difference between the first water temperature WT1 and the third water temperature WT3 after the chiller 17 starts operating is a difference resulting from the cooling of the cooling water by the chiller 17. The value obtained by subtracting the first water temperature PRWT1B before switching from the third water temperature PRWT3B before switching is the first pre-switching temperature difference PRTD1B. The processing circuit 91 uses as the first condition (B1) for determining that the cooling water circuit 80 is in the first state that the first pre-switching temperature difference PRTD1B is less than a predetermined first default value DB1.

[0069] As shown in Figure 3, the first pre-switching temperature difference PRTD1B is "K6" - "K4BF". "K6" - "K4BF" is smaller than the first default value DB1. Therefore, the water temperature change shown in Figure 5 satisfies condition (B1).

[0070] In the second state, the cooling water cooled by the chiller 17 passes through the flow path switching valve 20, then through the fourth flow path 74, the radiator 30, the radiator flow path 79, and the third flow path 73, flows back into the flow path switching valve 20, and then flows into the second flow path 72. On the other hand, in the first state, the cooling water cooled by the chiller 17 passes through the flow path switching valve 20 and 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 chiller 17 is operating is smaller in the first state than in the second state. The value obtained by subtracting the cooled first water temperature CWT1 from the cooled second water temperature CWT2 is the temperature difference POTD2B after the second switching. The processing circuit 91 uses the second condition (B2) for determining that the cooling water circuit 80 is in the first state as follows: the temperature difference POTD2B after the second switching is less than a predetermined second default value DB2.

[0071] As shown in Figure 5, the temperature difference POTD2B after the second switchover at time "T5" is "K5" - "K4AF". "K5" - "K4AF" is less than or equal to the second default value DB2. Therefore, the water temperature change shown in Figure 5 satisfies condition (B2).

[0072] In the first state, cooling water cooled by the chiller 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 chiller 17 has started operating is greater than the temperature difference between the third water temperature WT3 and the first water temperature WT1 before the chiller 17 starts operating. The value obtained by subtracting the cooled first water temperature CWT1 from the cooled third water temperature CWT3 is the temperature difference POTD3B after the third switching. Therefore, the processing circuit 91 uses the fact that the temperature difference POTD3B after the third switching is greater than a predetermined third default value DB3 as the third condition (B3) for determining that the cooling water circuit 80 is in the first state.

[0073] As shown in Figure 5, the temperature difference POTD3B after the third switchover at time "T5" is "K6" - "K4AF". "K6" - "K4AF" is greater than the third default value DB3. Therefore, the temperature transition shown in Figure 5 satisfies condition (B3).

[0074] <Effects of the second embodiment> In the second embodiment, in addition to the effects shown in (1-3) of the first embodiment, the following further effects are achieved.

[0075] (2-1) The diagnostic device 90 can diagnose whether the connection state of the flow path in the cooling water circuit 80 can be switched to the first normal state by determining whether all of conditions (B1), (B2), and (B3) are met.

[0076] <Example of changes> The following are some elements that can be modified in common with each of the above embodiments. The following examples of modifications can be combined with each other to the extent that they do not contradict each other technically.

[0077] The diagnostic device 90 may be configured to perform both the series of processes shown in Figure 2 and the series of processes shown in Figure 4. The processing circuit 91 may 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.

[0078] For example, when a predetermined time TE1 has elapsed since the cooling signal FC was sent to the chiller 17 while the vehicle was in motion, the processing circuit 91 acquires the pre-switching first water temperature PRWT1A, the pre-switching second water temperature PRWT2A, and the pre-switching third water temperature PRWT3A. The processing circuit 91 stores the acquired pre-switching first water temperature PRWT1A, pre-switching second water temperature PRWT2A, and pre-switching third water temperature PRWT3A in the storage device 92. Subsequently, when the processing circuit 91 executes the process of switching the cooling water circuit 80 to the first state while the chiller 17 is still operating, it acquires the post-switching first water temperature POWT1A and the post-switching second water temperature POWT2A after a predetermined time TE2 has elapsed. The processing circuit 91 uses the first pre-switching temperature PRWT1A, the second pre-switching temperature PRWT2A, and the third pre-switching temperature PRWT3A to calculate the first pre-switching temperature difference PRTD1A and the third pre-switching temperature difference PRTD3A. The processing circuit 91 uses the first post-switching temperature POWT1A and the second post-switching temperature POWT2A to calculate the second post-switching temperature difference POTD2A. Then, the processing circuit 91 determines whether conditions (A1), (A2), and (A3) are met.

[0079] The processing circuit 91 acquires, for example, the pre-switching first water temperature PRWT1B and the pre-switching third water temperature PRWT3B while the vehicle is in motion. The processing circuit 91 stores the acquired pre-switching first water temperature PRWT1B and pre-switching third water temperature PRWT3B in the storage device 92. Subsequently, if a switching signal C1 is sent towards the flow path switching valve 20 and then a cooling signal FC is sent towards the chiller 17 due to factors such as the need to cool the battery cell 10A, the following processing is performed. That is, after a predetermined time TE3 has elapsed since the transmission of the cooling signal FC, the post-cooling first water temperature CWT1, post-cooling second water temperature CWT2, and post-cooling third water temperature CWT3 are acquired. The processing circuit 91 uses the first water temperature PRWT1B before switching, 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.

[0080] The processing circuit 91 may be configured to execute, for example, the series of processes shown in Figure 2 and the series of processes shown in Figure 4 when the vehicle user selects a diagnostic item for the flow path switching valve 20 displayed on the vehicle's display.

[0081] The vehicle is not limited to electric vehicles. The vehicle only needs to have battery cells 10A housed in a battery pack 10. The vehicle may be, for example, a plug-in hybrid electric vehicle (PHEV).

[0082] The in-vehicle equipment provided with the second water jacket 32 ​​is not limited to the in-vehicle charger 31. Any in-vehicle equipment that generates heat can be provided with the second water jacket 32.

[0083] The oil cooler 40 and the third water jacket 37 do not necessarily have to be provided in the flow path between the outlet 34 of the second water jacket 32 ​​and the third port P3. [Explanation of Symbols]

[0084] 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 installed in a vehicle's cooling water circuit, which selectively switches the connection state between an upstream flow path and a downstream flow path from among multiple connection states to switch the path through which the cooling water circulates, The system includes a processing circuit that transmits a switching signal to the flow path switching valve to operate the flow path switching valve, When the water temperature of the cooling water upstream of the flow path switching valve before the switching signal is transmitted is defined as the upstream water temperature before switching, the water temperature of the cooling water downstream of the flow path switching valve before the switching signal is transmitted is defined 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 the switching signal was transmitted is defined 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 the switching signal was transmitted is defined as the downstream water temperature after switching, The aforementioned processing circuit is When the switching signal is transmitted to the flow path switching valve to switch the connection state to a default connection state among the plurality of connection states, The flow path switching valve is determined to be operating normally based on the fact that both the pre-switching temperature difference, which is the difference between the upstream water temperature before switching and the downstream water temperature before switching, and the post-switching temperature difference, which is the difference between the upstream water temperature after switching and the downstream water temperature after switching, satisfy the respective specified conditions. Diagnostic device for flow path switching valves.

2. The cooling water circuit comprises a first water jacket in which heat exchange takes place between the battery cells housed in the battery pack and the cooling water, a chiller for cooling the cooling water, a radiator for cooling the cooling water, and a second water jacket in which heat exchange takes place between the on-board equipment that generates heat and the cooling water. A chiller flow path from the outlet of the first water jacket to the inlet of the chiller, 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 chiller 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 chiller. The system comprises a first water temperature sensor for measuring the first water temperature, which is the water temperature of the cooling water in the first flow path; a second water temperature sensor for measuring the second water temperature, which is the water temperature of the cooling water in the second flow path; and a third water temperature sensor for measuring the third water temperature, which is the water temperature of the cooling water in the third flow path. The flow path switching valve comprises 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 determines the connection state. A first state in which the first port and the second port are connected, the first port and the fourth port are disconnected, the third port and the fourth port are connected, the third port and the second port are disconnected, and the fifth port is shielded, A second state in which the first port and the second port are blocked, the first port and the fourth port are connected, the third port and the fourth port are blocked, the third port and the second port are connected, and the fifth port is shielded. A third state in which the first port and the second port are blocked, the first port and the fourth port are connected, the third port and the fourth port are blocked, the third port and the fifth port are connected, and the second port is shielded. It is configured to be switchable to a fourth state in which the first port and the second port are blocked, the first port and the fourth port are blocked, the third port and the fourth port are connected, the third port and the second port are blocked, and the first port and the fifth port are connected. The default connection state is the first state, The processing circuit, while operating the chiller, acquires the first water temperature (pre-switching first water temperature), the second water temperature (pre-switching second water temperature) before transmitting the switching signal to the flow path switching valve, and the third water temperature (pre-switching third water temperature) before transmitting the switching signal to the flow path switching valve. After obtaining the first water temperature before switching, the second water temperature before switching, and the third water temperature before switching, the switching signal to switch to the predetermined connection state is transmitted to the flow path switching valve. After a predetermined time has elapsed since transmitting the switching signal to switch to the default connection state, the following steps are performed: obtain the first water temperature after switching, which is the first water temperature after the predetermined time has elapsed, and the second water temperature after switching, which is the second water temperature after the predetermined time has elapsed. The first pre-switching temperature difference, which is the value obtained by subtracting the first pre-switching water temperature from the second pre-switching water temperature, is greater than a predetermined value, and the second post-switching temperature difference, which is the value obtained by subtracting the first post-switching water temperature from the second post-switching water temperature, is less than or equal to the predetermined value. Furthermore, if the value obtained by subtracting the first water temperature before switching from the third water temperature before switching is defined as the third pre-switching temperature difference, then the value obtained by subtracting the lower limit of the possible values ​​of the second water temperature in the second state from the third pre-switching temperature difference is greater than the second post-switching temperature difference, The system determines that the connection state of the cooling water circuit has been switched to the first state, and that the flow path switching valve is performing normal operation to switch the connection state of the cooling water circuit to the first state. A diagnostic device for a flow path switching valve according to claim 1.

3. The in-vehicle device is an in-vehicle charger that converts AC power supplied from an external source into DC power to charge the battery cells, and is applied to a cooling water circuit that includes an oil cooler that performs heat exchange between lubricating oil that lubricates the motor, which is the power source of the vehicle, and the cooling water, and a third water jacket that performs heat exchange between a power control unit that controls the power of the motor and the cooling water. A diagnostic device for a flow path switching valve according to claim 2.

4. The cooling water circuit comprises a first water jacket in which heat exchange takes place between the battery cells housed in the battery pack and the cooling water, a chiller for cooling the cooling water, a radiator for cooling the cooling water, and a second water jacket in which heat exchange takes place between the on-board equipment that generates heat and the cooling water. A chiller flow path from the outlet of the first water jacket to the inlet of the chiller, 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 chiller 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 chiller. The system comprises a first water temperature sensor for measuring the first water temperature, which is the water temperature of the cooling water in the first flow path; a second water temperature sensor for measuring the second water temperature, which is the water temperature of the cooling water in the second flow path; and a third water temperature sensor for measuring the third water temperature, which is the water temperature of the cooling water in the third flow path. The flow path switching valve comprises 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 determines the connection state. A first state in which the first port and the second port are connected, the first port and the fourth port are disconnected, the third port and the fourth port are connected, the third port and the second port are disconnected, and the fifth port is shielded, A second state in which the first port and the second port are blocked, the first port and the fourth port are connected, the third port and the fourth port are blocked, the third port and the second port are connected, and the fifth port is shielded. A third state in which the first port and the second port are blocked, the first port and the fourth port are connected, the third port and the fourth port are blocked, the third port and the fifth port are connected, and the second port is shielded. It is configured to be switchable to a fourth state in which the first port and the second port are blocked, the first port and the fourth port are blocked, the third port and the fourth port are connected, the third port and the second port are blocked, and the first port and the fifth port are connected. The default connection state is the first state, Before the processing circuit transmits the switching signal to the flow path switching valve to switch to the default connection state, it obtains the first water temperature before switching, which is the first water temperature before the switching signal is transmitted to the flow path switching valve, and the third water temperature before switching, which is the third water temperature before the switching signal is transmitted to the flow path switching valve. After obtaining the first water temperature before switching and the third water temperature before switching, the switching signal is transmitted to the flow path switching valve. After transmitting the switching signal, a cooling signal to activate the chiller is transmitted to the chiller. After a predetermined time has elapsed since the transmission of the cooling signal, the following are performed: first water temperature after cooling, which is the first water temperature after the predetermined time has elapsed; second water temperature after cooling, which is the second water temperature after the predetermined time has elapsed; and third water temperature after cooling, which is the third water temperature after the predetermined time has elapsed. The first pre-switching temperature difference, which is the value obtained by subtracting the first pre-switching water temperature from the third pre-switching water temperature, is less than a predetermined first default value, and the second post-switching temperature difference, which is the value obtained by subtracting the first post-cooling water temperature from the second post-cooling water temperature, is less than a predetermined second default value, and the third post-switching temperature difference, which is the value obtained by subtracting the first post-cooling water temperature from the third post-cooling water temperature, is greater than a predetermined third default value. The system determines that the connection state of the cooling water circuit has been switched to the first state, and that the flow path switching valve is performing normal operation to switch the connection state of the cooling water circuit to the first state. A diagnostic device for a flow path switching valve according to claim 1.

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