Failure detection device

Abstract

A failure detection device (20) comprises: a power generation control unit (70) that stops power generation of some of a plurality of fuel cells (30); a temperature acquisition unit (76) that acquires an inflow temperature (Ti) of a refrigerant and an outflow temperature (To) of the refrigerant; and a pump failure detection unit (78) that detects, after the power generation of the fuel cell is stopped, a failure of a pump (40) that circulates the refrigerant into the fuel cell subjected to the power generation stop, if a difference (Td) between the outflow temperature and the inflow temperature in the fuel cell subjected to the power generation stop is greater than or equal to a predetermined value (Tv).

Description

Failure Detection Device

[0001] The present disclosure relates to a failure detection device.

[0002] In recent years, research and development have been conducted on fuel cells that contribute to energy efficiency, in order to ensure access to affordable, reliable, sustainable, and advanced energy for more people. US Patent Application Publication No. 2023 / 0178762 discloses an FC system including a plurality of FC units and a controller. The controller compares measured values of refrigerant temperature of the FC units and notifies of an abnormality in a temperature sensor that outputs a different measured value.

[0003] There is a long-felt need for a failure detection device that can favorably detect failures in a fuel cell system.

[0004] An object of the present disclosure is to solve the above-described problems, and thereby contribute to energy efficiency.

[0005] Aspects of the present disclosure are fault detection devices for detecting a fault in a fuel cell system comprising: a plurality of fuel cells that generate electricity; a refrigerant flow path through which refrigerant supplied to each of the plurality of fuel cells flows, branching off from a common supply flow path connected to a refrigerant supply device, and through which refrigerant recovered from each of the plurality of fuel cells flows and merges with a common recovery flow path connected to the refrigerant supply device; a plurality of pumps that circulate the refrigerant inside each of the plurality of fuel cells; a plurality of inflow temperature sensors that measure the inflow temperature of the refrigerant flowing into each of the plurality of fuel cells; and a plurality of outflow temperature sensors that measure the outflow temperature of the refrigerant flowing out from inside each of the plurality of fuel cells, wherein the device detects a fault in a pump, wherein the plurality of pumps The fault detection device comprises: a power generation control unit that stops the power generation of some of the fuel cells; a temperature acquisition unit that acquires the inflow temperature of the refrigerant flowing into each of the plurality of fuel cells and the outflow temperature of the refrigerant flowing out from each of the plurality of fuel cells from an inflow temperature sensor and an outflow temperature sensor corresponding to the fuel cell, respectively; and a pump fault detection unit that, after the power generation of the fuel cell targeted for power generation stoppage by the power generation control unit has stopped, detects a fault in the pump that circulates the refrigerant inside the fuel cell targeted for power generation stoppage if the difference between the outflow temperature and the inflow temperature which is lower than the outflow temperature is greater than or equal to a predetermined value.

[0006] According to this disclosure, it is possible to effectively detect pump failures in fuel cell systems.

[0007] Figure 1 is an illustrative diagram of a fuel cell system and a fault detection device. Figure 2 is a time chart showing the temporal changes in the state of the fuel cell system. Figure 3A is a diagram illustrating the detection of pump failure in a fuel cell system. Figure 3B is a diagram illustrating the detection of failures of the inlet temperature sensor and outlet temperature sensor in a fuel cell system. Figure 4 is a flowchart illustrating the processing procedure for fault detection in a fuel cell system. Figure 5 is a diagram illustrating fault detection in a fuel cell system.

[0008] Large vehicles may be equipped with multiple fuel cells. When a large vehicle is stationary or moving at a low speed, the power output required by the multiple fuel cells is not high. In that case, even if some of the fuel cells stop, the power output requirement can be met as long as the remaining fuel cells continue to generate power. In a state where multiple fuel cells are generating power at such low output, the fault detection device according to one embodiment described below detects a pump failure in the fuel cell system.

[0009] Figure 1 is a diagram illustrating a fuel cell system 10 and a fault detection device 20. The fuel cell system 10 includes a plurality of fuel cells 30 that generate electricity and a refrigerant supply device 32 that supplies refrigerant to the plurality of fuel cells 30. In the example shown in Figure 1, the fuel cell system 10 has three fuel cells 30A, 30B, and 30C.

[0010] The fuel cell system 10 has a refrigerant flow path. The refrigerant flow path includes a supply flow path 34 and a recovery flow path 36 common to the plurality of fuel cells 30, and a refrigerant flow path 38 corresponding to each of the plurality of fuel cells 30. The supply flow path 34 and the recovery flow path 36 are connected to a refrigerant supply device 32. The refrigerant supply device 32 cools the refrigerant flowing in through the recovery flow path 36. The refrigerant supply device 32 discharges the cooled refrigerant into the supply flow path 34 and allows it to flow through the supply flow path 34.

[0011] The refrigerant supplied from the refrigerant supply device 32 to each of the multiple fuel cells 30 flows through the supply channel 34 and then through the refrigerant channel 38 that branches off from the supply channel 34. The refrigerant supplied to each fuel cell 30 flows into the interior of each fuel cell 30. The refrigerant that has flowed into the interior of each fuel cell 30 flows through the refrigerant channel 38 inside each fuel cell 30 and then flows out from the interior of each fuel cell 30. In this way, refrigerant is recovered from each of the multiple fuel cells 30. The refrigerant recovered from each fuel cell 30 flows through the refrigerant channel 38 and then through the recovery channel 36 where the refrigerant channels 38 converge.

[0012] The fuel cell system 10 has a plurality of pumps 40, each corresponding to a plurality of fuel cells 30. The plurality of pumps 40 circulate refrigerant inside each of the plurality of fuel cells 30, as will be described later. The fuel cell system 10 has a plurality of switching valves 42, each corresponding to a plurality of fuel cells 30. The fuel cell system 10 has a plurality of bypass passages 44, each corresponding to a plurality of fuel cells 30. In the refrigerant passage 38 corresponding to each fuel cell 30, each pump 40 and each switching valve 42 is provided in the inflow section through which the refrigerant supplied to each fuel cell 30 flows toward each fuel cell 30.

[0013] Each bypass channel 44 branches off from the inflow section of the refrigerant channel 38 upstream of the pump 40 and bypasses the fuel cell 30 without passing through it. The bypass channel 44 merges with the outflow section of the refrigerant channel 38 corresponding to the fuel cell 30, through which the refrigerant recovered from the fuel cell 30 flows.

[0014] The switching valve 42 is installed at the point where the bypass flow path 44 branches off from the inflow section of the refrigerant flow path 38. The switching valve 42 can output a portion of the refrigerant supplied from the refrigerant supply device 32 and flowing through the aforementioned inflow section to the bypass flow path 44. That is, a portion of the refrigerant supplied from the refrigerant supply device 32 flows into the bypass flow path 44 from the section of the inflow section of the refrigerant flow path 38 upstream of the switching valve 42. The remaining portion of the refrigerant supplied from the refrigerant supply device 32 flows into the section of the inflow section of the refrigerant flow path 38 downstream of the switching valve 42, from the section upstream of the switching valve 42.

[0015] The refrigerant that flows from the inlet section of the refrigerant flow path 38 into the bypass flow path 44 flows through the bypass flow path 44, flows through the aforementioned outlet section, and returns to the refrigerant supply device 32. The remaining refrigerant is not output to the bypass flow path 44, but flows toward the fuel cell 30 through the section downstream of the aforementioned switching valve 42. The pump 40 provided in this downstream section circulates the refrigerant flowing through this downstream section into the inside of the fuel cell 30.

[0016] In this embodiment, when the switching valve 42 is fully open, the switching valve 42 blocks the inflow of refrigerant from the section of the refrigerant flow path 38 upstream of the switching valve 42 to the bypass flow path 44. In this case, the entire amount of refrigerant supplied from the refrigerant supply device 32 and flowing through the inflow section of the refrigerant flow path 38 flows through the section downstream of the switching valve 42. That is, the pump 40 circulates the entire amount of refrigerant supplied from the refrigerant supply device 32 and flowing through the inflow section of the refrigerant flow path 38 inside the fuel cell 30.

[0017] When the switching valve 42 is fully closed, the switching valve 42 blocks the inflow of refrigerant supplied from the refrigerant supply device 32. The refrigerant supplied from the refrigerant supply device 32 is not supplied to the fuel cell 30 and does not flow into the bypass passage 44. The pump 40 circulates the refrigerant flowing downstream of the switching valve 42 into the inside of the fuel cell 30. The refrigerant that flows out from inside the fuel cell 30 flows in the reverse direction through the bypass passage 44 and is output again to the section downstream of the switching valve 42 by the switching valve 42. In other words, the pump 40 circulates the refrigerant in a closed circuit formed by a part of the refrigerant passage 38 and the bypass passage 44.

[0018] The fuel cell system 10 has multiple inlet temperature sensors 46 and multiple outlet temperature sensors 48, each corresponding to one of the multiple fuel cells 30. The multiple inlet temperature sensors 46 each measure the inlet temperature Ti of the refrigerant flowing into the multiple fuel cells 30. The multiple outlet temperature sensors 48 each measure the outlet temperature To of the refrigerant flowing out from the multiple fuel cells 30. As will be described later, based on the measured inlet temperature Ti and outlet temperature To, a failure of the pump 40 corresponding to the fuel cell 30 whose power generation has stopped is detected.

[0019] In this embodiment, as shown in Figure 1, the inlet temperature sensor 46 is provided in the fuel cell 30. This allows for accurate measurement of the refrigerant inlet temperature Ti. However, the inlet temperature sensor 46 may be provided at other locations within the aforementioned inlet section of the refrigerant flow path 38. For example, the inlet temperature sensor 46 may be provided upstream of the switching valve 42.

[0020] Furthermore, two inflow temperature sensors 46 may be provided, one at the fuel cell 30 and the other upstream of the switching valve 42. In this case, the inflow temperature Ti measured by either or both of the two inflow temperature sensors 46 may be used to detect a malfunction in the pump 40 corresponding to the fuel cell 30 when power generation has stopped.

[0021] In this embodiment, as shown in Figure 1, the outlet temperature sensor 48 is provided on the fuel cell 30. However, the outlet temperature sensor 48 may be provided at any other location within the aforementioned outlet section of the refrigerant flow path 38.

[0022] Figure 1 shows a block diagram illustrating the configuration of the fault detection device 20. The fault detection device 20 detects a fault in the pump 40 of the fuel cell system 10. The fault detection device 20 has a calculation unit 60 and a storage unit 62. The calculation unit 60 is a computer and includes a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). In other words, the calculation unit 60 includes processing circuitry.

[0023] The storage unit 62 is a recording medium that can be read by a computer. The storage unit 62 includes volatile memory such as RAM (Random Access Memory) and non-volatile memory such as ROM (Read Only Memory) or flash memory. The volatile memory is used as the working memory of the processor. The non-volatile memory stores computer programs executed by the processor, a predetermined value Tv and a predetermined time Cp used for detecting failures of the pump 40, which will be described later.

[0024] Computer programs (computer software) executed by a processor can also be called computer program products. Computer program products are not limited to computer programs stored on recording media, but also include computer programs transmitted, distributed, or downloaded via the internet, etc.

[0025] The calculation unit 60 includes a power generation control unit 70, a pump control unit 72, a switching valve control unit 74, a temperature acquisition unit 76, a pump failure detection unit 78, and a temperature sensor failure detection unit 80. The calculation unit 60 executes a computer program stored in the storage unit 62 to realize the power generation control unit 70, the pump control unit 72, the switching valve control unit 74, the temperature acquisition unit 76, the pump failure detection unit 78, and the temperature sensor failure detection unit 80.

[0026] At least a portion of the power generation control unit 70, the pump control unit 72, the switching valve control unit 74, the temperature acquisition unit 76, the pump failure detection unit 78, and the temperature sensor failure detection unit 80 may be implemented by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array), or by an electronic circuit including discrete devices.

[0027] The power generation control unit 70 may stop power generation in some of the fuel cells 30 if both the power output conditions and the outlet temperature conditions in each of the fuel cells 30 are met. The power output conditions are met if the power output of each of the fuel cells 30 is less than or equal to a predetermined output Pp. The outlet temperature conditions are met if the outlet temperature To of the refrigerant flowing out from inside each of the fuel cells 30 is less than or equal to a predetermined temperature Tp.

[0028] The detection of a pump 40 failure, as described later, is performed periodically, for example. The fuel cell 30 to be shut down is determined by sequential switching, for example. Suppose that the power generation of fuel cell 30C was shut down when the pump 40 failure was detected last time. In that case, the power generation control unit 70 determines, for example, a fuel cell 30A different from fuel cell 30C, as the fuel cell 30 to be shut down when the pump 40 failure is detected this time. In this embodiment, the fuel cell 30 to be shut down by the power generation control unit 70 is the single fuel cell 30A shown in Figure 1.

[0029] Therefore, the fuel cells 30 other than fuel cell 30A, which is the target of the power generation shutdown this time, are the two fuel cells 30B and 30C shown in Figure 1. As will be described later, the power generation control unit 70 can control the power generation output of fuel cells 30B and 30C other than fuel cell 30A, which is the target of the power generation shutdown.

[0030] The pump control unit 72 determines the rotational speed of the multiple pumps 40. The pump control unit 72 controls the multiple pumps 40 based on the determined rotational speed. Each pump 40 operates according to the rotational speed determined by the pump control unit 72, unless it is malfunctioning. Figure 1 shows three pumps 40A, 40B, and 40C that circulate refrigerant inside three fuel cells 30A, 30B, and 30C, respectively. The pump control unit 72 determines the rotational speed of each of the three pumps 40A, 40B, and 40C, and controls each of the three pumps 40A, 40B, and 40C based on the determined rotational speed.

[0031] The switching valve control unit 74 controls a plurality of switching valves 42. By controlling each switching valve 42 and adjusting the opening degree of each switching valve 42, the switching valve control unit 74 can set each switching valve 42 to a fully open state, a fully closed state, or an intermediate state between the fully open state and the fully closed state.

[0032] The temperature acquisition unit 76 acquires the inflow temperature Ti of the refrigerant flowing into each of the multiple fuel cells 30 from the inflow temperature sensor 46 corresponding to each fuel cell 30. The temperature acquisition unit 76 acquires the outflow temperature To of the refrigerant flowing out from each of the multiple fuel cells 30 from the outflow temperature sensor 48 corresponding to each fuel cell 30.

[0033] The pump failure detection unit 78 detects a failure in the pump 40 that circulates refrigerant inside the fuel cell 30, which is the target of power generation shutdown, based on the inflow temperature Ti and outflow temperature To obtained by the temperature acquisition unit 76. As described above, in this embodiment, the fuel cell 30A is the target of power generation shutdown. Therefore, the pump failure detection unit 78 detects a failure in the pump 40A corresponding to the fuel cell 30A based on the inflow temperature Tia of the refrigerant flowing into the fuel cell 30A and the outflow temperature Toa of the refrigerant flowing out from the fuel cell 30A.

[0034] The temperature sensor failure detection unit 80 detects failures in the inlet temperature sensor 46 and the outlet temperature sensor 48 based on the inlet temperature Ti and outlet temperature To acquired by the temperature acquisition unit 76. In this embodiment, power generation from fuel cell 30A is stopped, while power generation from fuel cells 30B and 30C continues.

[0035] The temperature sensor failure detection unit 80 detects a failure in either of the inlet temperature sensors 46B and 46C corresponding to the fuel cells 30B and 30C based on the inlet temperatures Tib and Tic measured by the inlet temperature sensors 46B and 46C, respectively. The temperature sensor failure detection unit 80 also detects a failure in either of the outlet temperature sensors 48B and 48C corresponding to the fuel cells 30B and 30C based on the outlet temperatures Tob and Toc measured by the outlet temperature sensors 48B and 48C, respectively.

[0036] Figure 2 is a time chart showing the temporal changes in the state of the fuel cell system 10. As described above, the power generation control unit 70 of the fault detection device 20 can stop the power generation of some of the fuel cells 30 if the power generation output of each of the fuel cells 30 is below a predetermined output Pp. In the example shown in Figure 2, at time C0, when the power generation output of each fuel cell 30 is below a predetermined output Pp, the power generation control unit 70 stops the power generation of the fuel cell 30A that is subject to power generation stoppage.

[0037] Assume that the power output of at least one fuel cell 30 is greater than a predetermined output Pp. If some of the fuel cells 30 stop generating power in this state, the remaining fuel cells 30 may not be able to generate enough power to meet the required output. For example, this could result in a large vehicle equipped with multiple fuel cells 30 being unable to continue high-speed driving.

[0038] As described above, if the power output of each fuel cell 30 falls below a predetermined output Pp, the power generation of some of the fuel cells 30 can be stopped. This allows the required output to be met by the power generation of the remaining fuel cells 30. In other words, a failure of the pump 40 can be detected without affecting the utilization of the power output of multiple fuel cells 30. The predetermined output Pp is determined in advance and stored in the storage unit 62 of the fault detection device 20.

[0039] Furthermore, as described above, if the outlet temperature To of the refrigerant flowing out from inside each fuel cell 30 is below a predetermined temperature Tp, the power generation of some of the fuel cells 30 can be stopped. This prevents drying caused by high temperatures inside the fuel cells 30 that are not generating power, and the resulting deterioration of those fuel cells 30. In other words, a failure of the pump 40 can be detected without affecting the lifespan of the fuel cells 30. The predetermined temperature Tp is determined in advance and stored in the memory unit 62 of the failure detection device 20.

[0040] The predetermined temperature Tp is not predetermined, but may be determined according to the temperature of the fuel cell 30, the amount of water produced, the power generation current value, etc., immediately before the power generation of the fuel cell 30 is stopped. Alternatively, the measured value of the power generation current and the predetermined current value may be used instead of the refrigerant outlet temperature To and the predetermined temperature Tp.

[0041] As described above, since the power generation of fuel cell 30A stops at time C0, the power output of fuel cell 30A becomes zero or an equivalent value, as shown in Figure 2. At time C0, the power generation control unit 70 increases the power output of all fuel cells 30 other than fuel cell 30A, which is the one whose power generation is stopped. That is, the power output of fuel cells 30B and 30C is increased. This makes it possible to reduce the impact on the utilization of the power output of multiple fuel cells 30.

[0042] The increment of the power generation output of fuel cells 30B and 30C other than the fuel cell 30A subject to power generation stoppage is determined based on the power generation output before time C0 when the power generation of the fuel cell 30A subject to power generation stoppage is stopped. Until the power generation of the fuel cell 30A is stopped at time C0, the fuel cell 30A generates power as shown in FIG. 2. The power generation output of the fuel cell 30A that has been generating power until time C0 is covered by the increment of the power generation output of the fuel cells 30B and 30C at time C0. This makes it easy to determine a change in the refrigerant outflow temperature To described later when the pump 40A fails.

[0043] When it is assumed that the fuel cells 30B and 30C perform uniform power generation, half of the power generation output of the fuel cell 30A is equally distributed as the increment of the power generation output of the fuel cells 30B and 30C, respectively. That is, the power generation control unit 70 equalizes the increased power generation output of each of the fuel cells 30 other than the fuel cell 30A subject to power generation stoppage. This makes it easy to determine an increase in the refrigerant outflow temperature To described later when the pump 40A fails.

[0044] At time C0, since the power generation output of the fuel cells 30B and 30C increases, the rotation speeds of pumps 40B and 40C that circulate refrigerant into the respective interiors of the fuel cells 30B and 30C are increased. Note that the pump control unit 72 of the failure detection device 20 determines to match all the rotation speeds of the plurality of pumps 40. Further, the pump control unit 72 determines to increase all the rotation speeds of the plurality of pumps 40 compared to before the power generation of the fuel cell subject to power generation stoppage is stopped. That is, the rotation speed of the pump 40A that circulates refrigerant into the interior of the fuel cell 30A subject to power generation stoppage is also increased in the same manner as the rotation speeds of the pumps 40B and 40C. The rotation speeds of the pumps 40A, 40B and 40C match each other.

[0045] Accordingly, if the flow rate of the refrigerant flowing through the section downstream of the switching valve 42 in the inflow section of the refrigerant flow path 38 is uniform, the flow rate of the refrigerant flowing inside each fuel cell 30 can be made uniform. In this case, it becomes easy to determine an increase in the refrigerant outflow temperature To flowing out from the fuel cell 30 that is subject to power generation stoppage in response to a failure of the pump 40 that circulates the refrigerant inside the fuel cell 30. The detection of a failure of the pump 40 using the outflow temperature To will be described later.

[0046] At time C0, the switching valve control unit 74 of the failure detection device 20 controls the plurality of switching valves 42 to equalize the flow rate of the refrigerant flowing through the section downstream of the switching valve 42 in the inflow section of the refrigerant flow path 38. That is, the switching valve control unit 74 matches all the flow rates of the refrigerant that respectively circulate inside the plurality of fuel cells 30.

[0047] The switching valve control unit 74 can match all the flow rates of the refrigerant that respectively circulate inside the plurality of fuel cells 30 by adjusting the opening degree of each switching valve 42. This can be easily achieved by adjusting each switching valve 42 to the fully open state described above. As shown in FIG. 2, the switching valve control unit 74 controls the switching valve 42 corresponding to each of the plurality of fuel cells 30 at time C0, and adjusts the opening degree of each switching valve 42 so that each switching valve 42 is brought into a fully open state. Thereby, the switching valve control unit 74 blocks the inflow of the refrigerant from the refrigerant flow path 38 to the bypass flow path 44.

[0048] In this case, the entire amount of the refrigerant supplied from the refrigerant supply device 32 and flowing through the inflow section of the refrigerant flow path 38 can flow inside each fuel cell 30. Therefore, all the flow rates of the refrigerant flowing inside the plurality of fuel cells 30 can be matched. This makes it easy to determine a change in the refrigerant outflow temperature To, which will be described later, when the pump 40A fails.

[0049] Furthermore, the inlet temperatures Ti of the refrigerant flowing into the interior of multiple fuel cells 30 are approximately the same. Also, the outlet temperatures To of the refrigerant flowing out from fuel cells 30 other than the fuel cell 30 targeted for power generation shutdown are approximately the same. Since the fuel cells 30 other than the fuel cell 30 targeted for power generation shutdown are generating power, the outlet temperature To of the refrigerant in those fuel cells 30 is higher than the inlet temperature Ti of the refrigerant.

[0050] In other words, the inflow temperatures Tia, Tib, and Tic of the refrigerant flowing into the fuel cells 30A, 30B, and 30C are approximately the same. The outflow temperatures Tob and Toc of the refrigerant flowing out from the fuel cells 30B and 30C are approximately the same. The outflow temperature Tob in fuel cell 30B is higher than the inflow temperature Tib. The outflow temperature Toc in fuel cell 30C is higher than the inflow temperature Tic.

[0051] Since the fuel cell 30, which is subject to power generation shutdown, is not generating power, the refrigerant outlet temperature To in the fuel cell 30 is approximately equal to the refrigerant inlet temperature Ti. In other words, the refrigerant outlet temperature Toa in fuel cell 30A is approximately equal to the refrigerant inlet temperature Tia.

[0052] However, Figure 2 shows an example of refrigerant temperature change when the pump 40A corresponding to the fuel cell 30A fails. Because the pump 40A failed at time C0 when the power generation of the fuel cell 30A was stopped, it becomes difficult for the refrigerant to circulate inside the fuel cell 30A. That is, the refrigerant flow rate decreases, and the refrigerant tends to accumulate inside the fuel cell 30A and in the refrigerant flow path 38.

[0053] The aforementioned outflow section of the refrigerant flow path 38 for the refrigerant flowing out from inside the fuel cell 30A connects with another refrigerant flow path 38 at the point where the outflow section merges with the recovery flow path 36. High-temperature refrigerant flowing out from inside the other fuel cells 30B and 30C, which are generating electricity, flows through the other refrigerant flow path 38.

[0054] As described above, because pump 40A has failed, the flow rate of refrigerant decreases in the aforementioned outflow section of the refrigerant flow path 38 for refrigerant flowing out from inside fuel cell 30A, and the refrigerant tends to accumulate in the refrigerant flow path 38. Therefore, the temperature in this outflow section rises due to the influence of the high-temperature refrigerant flowing out from inside the other fuel cells 30B and 30C. In other words, the outflow temperature Toa of the refrigerant flowing out from inside fuel cell 30A gradually increases with the passage of time from time C0 onward. The outflow temperature Toa of the refrigerant rises to the temperature corresponding to the outflow temperatures Tob and Toc of the refrigerant mentioned above.

[0055] Therefore, if the pump 40A fails, after time C0, the refrigerant outlet temperature Toa in the fuel cell 30A will be different from the inlet temperature Tia, which is lower than the refrigerant outlet temperature Toa. The refrigerant inlet temperature Tia is lower than the refrigerant outlet temperature Toa. Thus, by detecting that the difference Td between the refrigerant outlet temperature Toa and the inlet temperature Tia in the fuel cell 30A is greater than or equal to a predetermined value Tv, the failure of the pump 40A can be detected.

[0056] The pump failure detection unit 78 of the failure detection device 20 detects a failure in the pump 40 that circulates refrigerant inside the fuel cell 30 after the power generation of the fuel cell 30, which is subject to power generation shutdown by the power generation control unit 70, has been stopped. The failure of the pump 40 is detected when the difference Td between the refrigerant outlet temperature To and the lower inlet temperature Ti in the fuel cell 30 is greater than or equal to a predetermined value Tv. This allows for reliable detection of failures in the pump 40 in the fuel cell system 10.

[0057] As shown in Figure 2, immediately after time C0 when the power generation of the fuel cell 30A, which is the target of the power generation shutdown, is stopped, the difference Td between the outlet temperature To = Toa and the inlet temperature Ti = Tia is small. As described above, the outlet temperature Toa of the refrigerant rises to the temperature corresponding to the outlet temperatures Tob and Toc of the refrigerant described above after time C0. Accordingly, the difference Td also increases. Therefore, it is preferable to detect the failure of the pump 40 after the difference Td has increased sufficiently.

[0058] The time required for the difference Td to increase sufficiently is measured experimentally in advance, and a predetermined time Cp, which is the elapsed time from time C0, is determined based on the measured value. The determined predetermined time Cp is stored in the memory unit 62 of the fault detection device 20. That is, the pump fault detection unit 78 detects a fault in the pump 40 that circulates refrigerant inside the fuel cell 30 after a predetermined time Cp has elapsed since the power generation of the fuel cell 30, which is the target of power generation shutdown, has been stopped. This makes it possible to detect a fault in the pump 40 in the fuel cell system 10 more effectively.

[0059] In the example shown in Figure 2, at time C1, after a predetermined time Cp has elapsed from time C0 when the power generation of fuel cell 30A is stopped, the refrigerant outlet temperature Toa and inlet temperature Tia in fuel cell 30A are obtained, and the difference Td between them is calculated. Based on whether or not this difference Td is greater than or equal to a predetermined value Tv, a fault detection of pump 40 is performed. If no fault is detected, at a subsequent time C2, power generation of fuel cell 30A is restarted, and the power output of fuel cells 30B and 30C, which had increased at time C0, is returned to its original output value.

[0060] Figure 3A is a diagram illustrating the detection of a pump 40 failure in the fuel cell system 10. The pump failure detection unit 78 of the failure detection device 20 performs a temperature comparison between the difference Td between the refrigerant outlet temperature Toa and the inlet temperature Tia in the fuel cell 30A, which is subject to power generation shutdown, and a predetermined value Tv. Based on this temperature comparison, the pump failure detection unit 78 determines whether or not a pump failure has occurred in the pump 40.

[0061] If the difference Td between the refrigerant outlet temperature Toa and the inlet temperature Tia in the fuel cell 30A is greater than or equal to a predetermined value Tv, the pump failure detection unit 78 determines that a pump failure has occurred. In other words, a pump failure of 40 is detected. If the difference Td is less than the predetermined value Tv, the pump failure detection unit 78 determines that a pump failure has not occurred.

[0062] The refrigerant outlet temperature Toa in the fuel cell 30A is obtained by the temperature acquisition unit 76 from the outlet temperature sensor 48A corresponding to the fuel cell 30A. The refrigerant inlet temperature Tia in the fuel cell 30A is obtained by the temperature acquisition unit 76 from the inlet temperature sensor 46A corresponding to the fuel cell 30A.

[0063] Figure 3B is a diagram illustrating the detection of failures in the inlet temperature sensor 46 and outlet temperature sensor 48 in the fuel cell system 10. As described above, the temperature sensor failure detection unit 80 of the failure detection device 20 detects failures in the inlet temperature sensor 46 and outlet temperature sensor 48 based on the inlet temperature Ti and outlet temperature To.

[0064] If the inflow temperature Ti of the refrigerant flowing into a fuel cell 30 other than the fuel cell 30 targeted for power generation shutdown does not match, a malfunction of the inflow temperature sensor 46 corresponding to that fuel cell 30 is detected. If the outflow temperature To of the refrigerant flowing out from a fuel cell 30 other than the fuel cell 30 targeted for power generation shutdown does not match, a malfunction of the outflow temperature sensor 48 corresponding to that fuel cell 30 is detected.

[0065] In this embodiment, the detection of failures in the inlet temperature sensor 46 and the outlet temperature sensor 48 is performed when the power generation of fuel cell 30A is stopped and fuel cells 30B and 30C are generating power. The temperature acquisition unit 76 acquires the refrigerant inlet temperature Tib in fuel cell 30B from the inlet temperature sensor 46B corresponding to fuel cell 30B. The temperature acquisition unit 76 acquires the refrigerant inlet temperature Tic in fuel cell 30C from the inlet temperature sensor 46C corresponding to fuel cell 30C.

[0066] The temperature sensor failure detection unit 80 compares the refrigerant inlet temperature Tib in fuel cell 30B with the refrigerant inlet temperature Tic in fuel cell 30C. Based on this temperature comparison, the temperature sensor failure detection unit 80 determines whether or not a failure has occurred in the inlet temperature sensor 46.

[0067] Assume that the refrigerant inlet temperature Tib in fuel cell 30B and the refrigerant inlet temperature Tic in fuel cell 30C are the same. Alternatively, the two temperatures may be considered to be the same if the difference between the refrigerant inlet temperature Tib in fuel cell 30B and the refrigerant inlet temperature Tic in fuel cell 30C falls within a predetermined range. In this case, the temperature sensor failure detection unit 80 determines that no failure has occurred in the inlet temperature sensor 46B corresponding to fuel cell 30B and the inlet temperature sensor 46C corresponding to fuel cell 30C. In other words, no failure is detected in the inlet temperature sensors 46B and 46C.

[0068] Assume that the refrigerant inlet temperature Tib in fuel cell 30B and the refrigerant inlet temperature Tic in fuel cell 30C do not match. Alternatively, if the difference between the refrigerant inlet temperature Tib in fuel cell 30B and the refrigerant inlet temperature Tic in fuel cell 30C falls outside a predetermined range, the two may be considered to be mismatched. In this case, the temperature sensor failure detection unit 80 determines that a failure has occurred in either the inlet temperature sensor 46B corresponding to fuel cell 30B or the inlet temperature sensor 46C corresponding to fuel cell 30C. That is, a failure in either the inlet temperature sensor 46B or the inlet temperature sensor 46C is detected by the temperature sensor failure detection unit 80.

[0069] The temperature acquisition unit 76 acquires the refrigerant discharge temperature Tob in fuel cell 30B from the discharge temperature sensor 48B corresponding to fuel cell 30B. The temperature acquisition unit 76 acquires the refrigerant discharge temperature Toc in fuel cell 30C from the discharge temperature sensor 48C corresponding to fuel cell 30C.

[0070] The temperature sensor failure detection unit 80 compares the refrigerant discharge temperature Tob in fuel cell 30B with the refrigerant discharge temperature Toc in fuel cell 30C. Based on this temperature comparison, the temperature sensor failure detection unit 80 determines whether or not a failure has occurred in the discharge temperature sensor 48.

[0071] Assume that the refrigerant discharge temperature Tob in fuel cell 30B and the refrigerant discharge temperature Toc in fuel cell 30C are the same. Alternatively, the two temperatures may be considered to be the same if the difference between the refrigerant discharge temperature Tob in fuel cell 30B and the refrigerant discharge temperature Toc in fuel cell 30C falls within a predetermined range. In this case, the temperature sensor failure detection unit 80 determines that no failure has occurred in the discharge temperature sensor 48B corresponding to fuel cell 30B and the discharge temperature sensor 48C corresponding to fuel cell 30C. In other words, no failure is detected in the discharge temperature sensors 48B and 48C.

[0072] Assume that the refrigerant discharge temperature Tob in fuel cell 30B and the refrigerant discharge temperature Toc in fuel cell 30C do not match. Alternatively, if the difference between the refrigerant discharge temperature Tob in fuel cell 30B and the refrigerant discharge temperature Toc in fuel cell 30C falls outside a predetermined range, the two may be considered to be inconsistent. In this case, the temperature sensor failure detection unit 80 determines that a failure has occurred in either the discharge temperature sensor 48B corresponding to fuel cell 30B or the discharge temperature sensor 48C corresponding to fuel cell 30C. That is, a failure in either the discharge temperature sensor 48B or the discharge temperature sensor 48C is detected by the temperature sensor failure detection unit 80.

[0073] In this way, failures of the inlet temperature sensor 46 and outlet temperature sensor 48 corresponding to fuel cells 30 other than the fuel cell 30 targeted for power generation shutdown can be detected. The fuel cells 30 other than the fuel cell 30 targeted for power generation shutdown may later be determined to be the fuel cell 30 targeted for power generation shutdown in order to detect failures of the pump 40. By detecting failures of the inlet temperature sensor 46 and outlet temperature sensor 48 in advance, the detection of failures of the pump 40 that may be performed later can be done effectively. In other words, if the detection of failures of the pump 40 corresponding to the fuel cell 30 other than the fuel cell 30 targeted for power generation shutdown is performed later, this can be done effectively.

[0074] Figure 4 is a flowchart illustrating the processing procedure for detecting a fault in the fuel cell system 10. This processing procedure is performed by the calculation unit 60 executing a computer program stored in the memory unit 62 of the fault detection device 20. When this processing procedure is started, in step S1, the power generation control unit 70 determines whether the power generation output of each of the multiple fuel cells 30 is less than or equal to a predetermined output Pp. If the answer in step S1 is YES, the processing procedure proceeds to step S2. If the answer in step S1 is NO, the processing procedure ends.

[0075] In addition, instead of determining in step S1 whether the power output of each of the multiple fuel cells 30 is less than or equal to a predetermined output Pp, the following determinations may be made. For example, a determination may be made as to whether the sum of the power output of the multiple fuel cells 30 is less than or equal to a predetermined output. Alternatively, a determination may be made as to whether the required power output of the multiple fuel cells 30 is less than or equal to a predetermined value.

[0076] In step S2, the temperature acquisition unit 76 acquires the outlet temperature To of the refrigerant flowing out from inside each of the multiple fuel cells 30 from the outlet temperature sensor 48 corresponding to each fuel cell 30. In step S3, the power generation control unit 70 determines whether the refrigerant outlet temperature To acquired in step S2 is below a predetermined temperature Tp. If the answer in step S3 is YES, the process proceeds to step S4. If the answer in step S3 is NO, the process ends.

[0077] In step S4, the power generation control unit 70 determines which fuel cell 30A is to be stopped from generating power. The fuel cell 30 to be stopped from generating power is determined by sequentially switching between multiple fuel cells 30 each time this processing procedure is performed. In step S5, the power generation control unit 70 stops the power generation of the fuel cell 30A determined in step S4. The power generation control unit 70 increases the power output of all fuel cells 30B and 30C other than the fuel cell 30A that is to be stopped from generating power. In step S6, the pump control unit 72 controls the multiple pumps 40 to increase the rotational speed of all of the multiple pumps 40.

[0078] In step S7, the switching valve control unit 74 controls the multiple switching valves 42 to adjust the opening degree of each of the multiple switching valves 42. In step S8, the pump failure detection unit 78 determines whether a predetermined time Cp has elapsed since the power generation of the fuel cell 30A was stopped in step S5. If the answer in step S8 is YES, the process proceeds to step S9. If the answer in step S8 is NO, the process returns to step S8.

[0079] In step S9, the temperature acquisition unit 76 acquires the inflow temperature Ti of the refrigerant flowing into each of the multiple fuel cells 30 from the inflow temperature sensor 46 corresponding to each fuel cell 30. The temperature acquisition unit 76 acquires the outflow temperature To of the refrigerant flowing out from each of the multiple fuel cells 30 from the outflow temperature sensor 48 corresponding to each fuel cell 30.

[0080] In step S10, the pump failure detection unit 78 determines whether the difference Td between the refrigerant outlet temperature Toa and the inlet temperature Tia in the fuel cell 30A, which was obtained in step S9, is greater than or equal to a predetermined value Tv. If the answer in step S10 is YES, the process proceeds to step S11. If the answer in step S10 is NO, the process proceeds to step S12. In step S11, the pump failure detection unit 78 detects a failure in the pump 40A corresponding to the fuel cell 30A.

[0081] In step S12, the temperature sensor failure detection unit 80 determines whether the refrigerant inlet temperatures Tib and Tic for fuel cells 30B and 30C, respectively, obtained in step S9, match. If the result in step S12 is YES, the process proceeds to step S14. If the result in step S12 is NO, the process proceeds to step S13. In step S13, the temperature sensor failure detection unit 80 detects a failure in the inlet temperature sensors 46B and 46C corresponding to fuel cells 30B and 30C based on the determination result in step S12.

[0082] In step S14, the temperature sensor failure detection unit 80 determines whether the refrigerant outlet temperatures Tob and Toc for fuel cells 30B and 30C, respectively, obtained in step S9, match. If the result in step S14 is YES, this process procedure ends. If the result in step S14 is NO, this process procedure proceeds to step S15. In step S15, the temperature sensor failure detection unit 80 detects a failure in the outlet temperature sensors 48B and 48C corresponding to fuel cells 30B and 30C based on the determination result in step S14. Once the processing in step S14 is complete, this process procedure ends.

[0083] The embodiments described above may be modified as follows. In the following modifications, explanations that overlap with the embodiments described above will be omitted.

[0084] (Modification 1) In the above-described embodiment, the fuel cell 30 that is subject to power generation shutdown by the power generation control unit 70 is one fuel cell 30. However, the fuel cell 30 that is subject to power generation shutdown by the power generation control unit 70 may be multiple fuel cells 30. It is sufficient that at least one fuel cell 30 is generating power in addition to the fuel cell 30 that is subject to power generation shutdown.

[0085] The temperature of the refrigerant flow path 38 in the aforementioned outflow section of each fuel cell 30 that has stopped generating power rises due to the influence of the high-temperature refrigerant flowing out from the fuel cell 30 that is still generating power. Therefore, a malfunction in each pump 40 corresponding to each fuel cell 30 can be detected based on whether the difference Td between the outflow temperature To and inflow temperature Ti of the refrigerant in each fuel cell 30 that is subject to power shutdown is greater than or equal to a predetermined value Tv.

[0086] (Modification 2) In the above-described embodiment, a failure of the pump 40 corresponding to the fuel cell 30 is detected after a predetermined time Cp has elapsed since the power generation of the fuel cell 30 that is subject to power generation shutdown was stopped. The failure of the pump 40 is detected based on the outlet temperature To and inlet temperature Ti of the refrigerant in the fuel cell 30. The outlet temperature To and inlet temperature Ti of the refrigerant are obtained from the inlet temperature sensor 46 and the outlet temperature sensor 48 corresponding to the fuel cell 30.

[0087] Failures in the inlet temperature sensor 46 and outlet temperature sensor 48 corresponding to the fuel cell 30 may be detected before a failure in the pump 40 corresponding to the fuel cell 30, which is subject to power generation shutdown, is detected.

[0088] Figure 5 is a diagram illustrating fault detection in the fuel cell system 10. Assume that the power generation of fuel cell 30A, one of the multiple fuel cells 30A, 30B, and 30C, stops at time C0. At time C0, the pump control unit 72 of the fault detection device 20 increases the rotation speeds of pumps 40A, 40B, and 40C and synchronizes them. In addition, the switching valve control unit 74 of the fault detection device 20 fully opens the multiple switching valves 42 corresponding to each of the multiple fuel cells 30. This makes it possible to synchronize the flow rate of refrigerant circulating inside each of the multiple fuel cells 30.

[0089] Furthermore, at time C0, the temperature acquisition unit 76 acquires the inflow temperature Tia of the refrigerant flowing into the fuel cell 30A, which is subject to power generation shutdown, and the outflow temperature Toa of the refrigerant flowing out from the fuel cell 30A. The inflow temperature Tia and outflow temperature Toa of the refrigerant in the fuel cell 30A are acquired from the inflow temperature sensor 46A and the outflow temperature sensor 48A, which are corresponding to the fuel cell 30A.

[0090] The temperature sensor failure detection unit 80 compares the inlet temperature Tia and outlet temperature Toa of the refrigerant in the fuel cell 30A. Based on this temperature comparison, the temperature sensor failure detection unit 80 determines whether or not a failure has occurred in the inlet temperature sensor 46A and the outlet temperature sensor 48A.

[0091] Assume that the inlet temperature Tia of the refrigerant flowing into the fuel cell 30A and the outlet temperature Toa of the refrigerant flowing out of the fuel cell 30A are the same. Alternatively, the two temperatures may be considered to be the same if the difference between the inlet temperature Tia of the refrigerant flowing into the fuel cell 30A and the outlet temperature Toa of the refrigerant flowing out of the fuel cell 30A falls within a predetermined range. In this case, the temperature sensor failure detection unit 80 determines that no failure has occurred in the inlet temperature sensor 46A and the outlet temperature sensor 48A corresponding to the fuel cell 30A. In other words, no failure of the inlet temperature sensor 46A and the outlet temperature sensor 48A is detected.

[0092] Assume that the inlet temperature Tia of the refrigerant flowing into the fuel cell 30A and the outlet temperature Toa of the refrigerant flowing out of the fuel cell 30A do not match. Alternatively, if the difference between the inlet temperature Tia of the refrigerant flowing into the fuel cell 30A and the outlet temperature Toa of the refrigerant flowing out of the fuel cell 30A falls outside a predetermined range, the two may be considered to be mismatched. In this case, the temperature sensor failure detection unit 80 determines that a failure has occurred in either the inlet temperature sensor 46A or the outlet temperature sensor 48A corresponding to the fuel cell 30A. That is, a failure in either the inlet temperature sensor 46A or the outlet temperature sensor 48A is detected.

[0093] If the temperature sensor failure detection unit 80 does not detect a failure in the inlet temperature sensor 46A or the outlet temperature sensor 48A, the pump failure detection unit 78 will detect a failure in the pump 40A. At time C1, after a predetermined time Cp has elapsed from time C0 when the fuel cell 30A, which is subject to power generation shutdown, is stopped, the temperature acquisition unit 76 will again acquire the inlet temperature Tia and outlet temperature Toa of the refrigerant in the fuel cell 30A.

[0094] The pump failure detection unit 78 performs a temperature comparison between the difference Td between the refrigerant inlet temperature Tia and outlet temperature Toa in the fuel cell 30A and a predetermined value Tv. Based on this temperature comparison, the pump failure detection unit 78 determines whether or not a failure has occurred in the pump 40A, thereby detecting a failure in the pump 40A. A detailed explanation of this process will be omitted as it will overlap with the explanation described above using Figure 3A.

[0095] According to this modified example 2, the malfunction of the pump 40 can be detected after the normal operation of the inlet temperature sensor 46 and outlet temperature sensor 48 corresponding to the fuel cell 30, which is the target of power generation shutdown, has been confirmed. Therefore, the accuracy of detecting the malfunction of the pump 40 can be further improved.

[0096] With regard to the embodiments and modifications described above, the following additional information is disclosed.

[0097] (Note 1) The fault detection device (20) of the present disclosure is a fault detection device for a fuel cell system (10) having a plurality of fuel cells (30) that generate electricity, a refrigerant flow path (38) through which refrigerant supplied to each of the plurality of fuel cells flows from a common supply flow path (34) connected to a refrigerant supply device (32) and the refrigerant recovered from each of the plurality of fuel cells flows and merges into a common recovery flow path (36) connected to the refrigerant supply device, a plurality of pumps (40) that circulate the refrigerant inside each of the plurality of fuel cells, a plurality of inflow temperature sensors (46) that measure the inflow temperature (Ti) of the refrigerant flowing into each of the plurality of fuel cells, and a plurality of outflow temperature sensors (48) that measure the outflow temperature (To) of the refrigerant flowing out from inside the plurality of fuel cells, and the fault detection device for the pumps in the fuel cell system (10) A fault detection device for detecting malfunctions, comprising: a power generation control unit (70) that stops the power generation of some of the plurality of fuel cells; a temperature acquisition unit (76) that acquires the inflow temperature of the refrigerant flowing into each of the plurality of fuel cells and the outflow temperature of the refrigerant flowing out from each of the plurality of fuel cells from an inflow temperature sensor and an outflow temperature sensor corresponding to the fuel cell, respectively; and a pump fault detection unit (78) that, after the power generation of the fuel cell targeted for power generation stoppage by the power generation control unit has stopped, detects a fault in the pump that circulates the refrigerant inside the fuel cell targeted for power generation stoppage if the difference (Td) between the outflow temperature and the inflow temperature which is lower than the outflow temperature is greater than or equal to a predetermined value (Tv). With such a configuration, a pump fault in a fuel cell system can be detected effectively.

[0098] (Note 2) In the fault detection device described in Note 1, the power generation control unit may stop the power generation of the fuel cell to be stopped if the outflow temperature of the refrigerant flowing out from inside each of the plurality of fuel cells is below a predetermined temperature (Tp). With such a configuration, a pump failure can be detected without affecting the lifespan of the fuel cell.

[0099] (Note 3) The fault detection device described in Note 1 may further include a pump control unit (72) that determines the rotation speeds of the multiple pumps to be the same and controls the multiple pumps based on the determined rotation speeds. With such a configuration, it becomes easier to determine the rise in the refrigerant outlet temperature when a pump fails.

[0100] (Note 4) In the fault detection device described in Note 3, the power generation control unit may decide to stop the power generation of the fuel cell that is subject to the power generation stoppage, and to increase the power output of all fuel cells other than the fuel cell subject to the power generation stoppage, and the pump control unit may decide to increase the rotational speed of all of the multiple pumps compared to before the power generation of the fuel cell subject to the power generation stoppage was stopped. With such a configuration, it becomes easier to determine the rise in the outflow temperature of the refrigerant when a pump fails.

[0101] (Note 5) In the fault detection device described in Note 4, the increase in the power output of fuel cells other than the fuel cell that is subject to power generation shutdown may be determined based on the power output of the fuel cell subject to power generation shutdown before power generation is stopped. With such a configuration, it becomes easier to determine the rise in the refrigerant outflow temperature when the pump fails.

[0102] (Note 6) In the fault detection device described in Note 4, the power generation control unit may equalize the increased power output of each of the fuel cells other than the fuel cell that is subject to power generation shutdown. With such a configuration, it becomes easier to determine the rise in the refrigerant outflow temperature when the pump fails.

[0103] (Note 7) The fault detection device described in Note 6 may further include a temperature sensor fault detection unit (80) that detects a fault in the inlet temperature sensor or outlet temperature sensor corresponding to a fuel cell if the inlet temperature of the refrigerant flowing into the fuel cell other than the fuel cell that is subject to power generation shutdown does not match, or if the outlet temperature of the refrigerant flowing out from the fuel cell does not match. With such a configuration, if a fault in a pump corresponding to a fuel cell other than the fuel cell that is subject to power generation shutdown is detected later, this can be done effectively.

[0104] (Note 8) In the fault detection device described in Note 1, the inflow temperature sensor may be provided in the fuel cell. With this configuration, the inflow temperature of the refrigerant can be measured accurately.

[0105] (Note 9) In the fault detection device described in Note 1, the power generation control unit may stop the power generation of the fuel cell that is subject to power generation stoppage when the power generation output of each of the plurality of fuel cells is below a predetermined output (Pp). With such a configuration, a pump failure can be detected without affecting the utilization of the power generation output of the plurality of fuel cells.

[0106] (Note 10) In the fault detection device described in Note 1, the pump fault detection unit may detect a pump fault after a predetermined time (Cp) has elapsed since the power generation of the fuel cell that is subject to power generation shutdown has been stopped. With such a configuration, pump faults in the fuel cell system can be detected more effectively.

[0107] (Note 11) A fault detection device according to any one of Notes 1 to 10, wherein the fuel cell system further comprises a bypass channel (44) that branches upstream of the pump from the refrigerant channel through which the refrigerant supplied to each of the plurality of fuel cells flows, bypasses the fuel cell, and joins the refrigerant channel through which the refrigerant recovered from the fuel cell flows, and a switching valve (42) provided at a position where it branches off from the refrigerant channel through which the refrigerant supplied to the fuel cell flows, and the fault detection device further comprises a switching valve control unit (74) that controls the switching valve to make the flow rates of the refrigerant circulating inside each of the plurality of fuel cells all equal. With such a configuration, it becomes easier to determine the rise in the outflow temperature of the refrigerant when the pump fails.

[0108] (Note 12) In the fault detection device described in Note 11, the switching valve control unit may control the switching valve corresponding to each of the plurality of fuel cells to block the inflow of the refrigerant from the refrigerant flow path to the bypass flow path. With such a configuration, it becomes easier to determine the rise in the outflow temperature of the refrigerant when the pump fails.

[0109] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above.

[0110] 10...Fuel cell system 20...Fault detection device 30...Fuel cell 32...Refrigerant supply device 34...Supply channel 36...Recovery channel 38...Refrigerant channel 40...Pump 42...Switching valve 44...Bypass channel 46...Inlet temperature sensor 48...Outlet temperature sensor 60...Calculation unit 62...Storage unit 70...Power generation control unit 72...Pump control unit 74...Switching valve control unit 76...Temperature acquisition unit 78...Pump fault detection unit 80...Temperature sensor fault detection unit

Claims

1. A fault detection device (20) for detecting a pump failure in a fuel cell system (10) having: a plurality of fuel cells (30) that generate electricity; a refrigerant flow path (38) through which refrigerant supplied to each of the plurality of fuel cells flows from a common supply flow path (34) connected to a refrigerant supply device (32) and the refrigerant recovered from each of the plurality of fuel cells flows and merges into a common recovery flow path (36) connected to the refrigerant supply device; a plurality of pumps (40) that circulate the refrigerant inside each of the plurality of fuel cells; a plurality of inflow temperature sensors (46) that measure the inflow temperature (Ti) of the refrigerant flowing into each of the plurality of fuel cells; and a plurality of outflow temperature sensors (48) that measure the outflow temperature (To) of the refrigerant flowing out from inside each of the plurality of fuel cells, wherein the fault detection device (20) detects a pump failure in the fuel cell system (10), and further comprises a power generation control unit (70) that stops the power generation of some of the plurality of fuel cells, A fault detection device comprising: a temperature acquisition unit (76) that acquires the inlet temperature of the refrigerant flowing into each of the plurality of fuel cells and the outlet temperature of the refrigerant flowing out from each of the plurality of fuel cells from an inlet temperature sensor and an outlet temperature sensor corresponding to the fuel cell, respectively; and a pump fault detection unit (78) that, after the power generation of the fuel cell targeted for power generation shutdown by the power generation control unit has been stopped, detects a fault in the pump that circulates the refrigerant inside the fuel cell targeted for power generation shutdown if the difference (Td) between the outlet temperature and the inlet temperature which is lower than the outlet temperature in the fuel cell targeted for power generation shutdown is greater than or equal to a predetermined value (Tv); 2. A fault detection device according to claim 1, wherein the power generation control unit can stop the power generation of a fuel cell that is subject to power generation stoppage when the outlet temperature of the refrigerant flowing out from inside each of the plurality of fuel cells is below a predetermined temperature (Tp).

3. A fault detection device according to claim 1, further comprising a pump control unit (72) that determines the rotational speeds of a plurality of pumps to be the same and controls the plurality of pumps based on the determined rotational speeds.

4. A fault detection device according to claim 3, wherein the power generation control unit stops the power generation of the fuel cell that is subject to power generation stoppage and increases the power output of all fuel cells other than the fuel cell that is subject to power generation stoppage, and the pump control unit determines to increase the rotational speed of all of the plurality of pumps compared to before the power generation of the fuel cell that is subject to power generation stoppage was stopped.

5. A fault detection device according to claim 4, wherein the increment in the power output of fuel cells other than the fuel cell targeted for power generation shutdown is determined based on the power output of the fuel cell targeted for power generation shutdown before power generation is shut off.

6. A fault detection device according to claim 4, wherein the power generation control unit equalizes the increased power output of each of the fuel cells other than the fuel cell that is subject to power generation shutdown.

7. A fault detection device according to claim 6, further comprising a temperature sensor fault detection unit (80) that detects a fault in the inlet temperature sensor or outlet temperature sensor corresponding to a fuel cell when the inlet temperature of the refrigerant flowing into the fuel cell other than the fuel cell that is subject to power generation shutdown does not match, or when the outlet temperature of the refrigerant flowing out from the fuel cell does not match.

8. A fault detection device according to claim 1, wherein the inlet temperature sensor is provided in the fuel cell.

9. A fault detection device according to claim 1, wherein the power generation control unit can stop the power generation of a fuel cell that is subject to power generation stoppage when the power generation output of each of the plurality of fuel cells is less than or equal to a predetermined output (Pp).

10. A fault detection device according to claim 1, wherein the pump fault detection unit detects a fault in the pump after a predetermined time (Cp) has elapsed since the power generation of the fuel cell that is subject to power generation shutdown has been stopped.

11. A fault detection device according to any one of claims 1 to 10, wherein the fuel cell system further comprises a bypass channel (44) that branches upstream of the pump from the refrigerant channel through which the refrigerant supplied to each of the plurality of fuel cells flows, bypasses the fuel cell, and joins the refrigerant channel through which the refrigerant recovered from the fuel cell flows, and a switching valve (42) provided at a position where it branches off from the refrigerant channel through which the refrigerant supplied to the fuel cell flows, and the fault detection device further comprises a switching valve control unit (74) that controls the switching valve to make the flow rates of the refrigerant circulating inside each of the plurality of fuel cells all equal.

12. A fault detection device according to claim 11, wherein the switching valve control unit controls the switching valve corresponding to each of the plurality of fuel cells to block the inflow of the refrigerant from the refrigerant flow path to the bypass flow path.

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