Cooling system for fuel cells

Abstract

To provide a cooling system for fuel cells capable of monitoring abnormalities in a cooling system with a relatively simple configuration.SOLUTION: The cooling system for fuel cells for cooling a fuel cell stack and an intercooler includes: a radiator, a stack cooling circuit, an intercooler cooling circuit, a bypass route, a flow control valve for adjusting the flow rate distribution to the bypass route, a first temperature sensor, a second temperature sensor, and a control unit that executes anomaly monitoring processing to monitor abnormalities in the cooling system. The anomaly monitoring processing includes a series of first determination processing to determine as abnormal when the flow split ratio by the flow control valve is 100 percent and when the difference between the value detected by the first temperature sensor and the value detected by the second temperature sensor is greater than or equal to a first predetermined value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a cooling system for a fuel cell. [Background technology]

[0002] Patent Document 1 describes a cooling system for a fuel cell that cools a fuel cell stack and an intercooler. This cooling system includes a radiator, a stack cooling circuit, an intercooler cooling circuit, a bypass path that bypasses the radiator, a flow control valve that adjusts the flow ratio to the bypass path, a temperature sensor that detects the temperature of the oxidizing gas after passing through the intercooler, and a control device. The control device estimates the temperature of the oxidizing gas after passing through the intercooler based on the temperature of the refrigerant after passing through the fuel cell stack, the temperature of the refrigerant after passing through the radiator, the pressure of the oxidizing gas after passing through the intercooler, etc., and determines that there is an abnormality in the cooling system when the difference between the estimated value and the value detected by the temperature sensor is equal to or greater than a predetermined value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-106901 Summary of the Invention [Problem to be solved by the invention]

[0004] In the cooling system described above, the temperature of the oxidizing gas after passing through the intercooler is estimated based on the values ​​detected by multiple sensors. Therefore, if an abnormality occurs in one of the sensors, an error will occur in the estimated value, and there is a risk that an abnormality in the cooling system will not be correctly determined.

[0005] In view of the above circumstances, the present specification provides a technique for monitoring abnormalities in a cooling system with a relatively simple configuration. [Means for solving the problem]

[0006] The technology disclosed in this specification is embodied in a fuel cell cooling system that cools a fuel cell stack and an intercooler that cools oxidizing gas supplied to the fuel cell stack. In a first aspect, the cooling system includes a radiator, a stack cooling circuit having a first refrigerant outbound path that sends refrigerant from the radiator to the fuel cell stack and a first refrigerant return path that returns the refrigerant from the fuel cell stack to the radiator, an intercooler cooling circuit having a second refrigerant outbound path that branches off from the first refrigerant outbound path and sends the refrigerant to the intercooler, and a second refrigerant return path that joins the first refrigerant return path from the intercooler and returns the refrigerant, a bypass path that branches off from the first refrigerant return path and bypasses the radiator to send the refrigerant to the first refrigerant outbound path, a flow control valve that is provided at a branch point where the bypass path branches off from the first refrigerant return path and adjusts the flow ratio to the bypass path, a first temperature sensor that is provided on the first refrigerant return path and detects the temperature of the refrigerant after passing through the fuel cell stack, and a second temperature sensor that detects the temperature of the oxidizing gas after passing through the intercooler, and a control device that executes an abnormality monitoring process to monitor abnormalities in the cooling system. The abnormality monitoring process includes a first determination process that determines that an abnormality has occurred when the diversion ratio by the flow control valve is 100 percent and the difference between the detected value by the first temperature sensor and the detected value by the second temperature sensor is equal to or greater than a first predetermined value.

[0007] In the above-described configuration, the refrigerant that has passed through the fuel cell stack is typically returned to the radiator via the first refrigerant outflow path and cooled there. However, when the flow control valve's diversion ratio is 100 percent, the refrigerant that has passed through the fuel cell stack is returned to the first refrigerant outflow path without passing through the radiator. A portion of the refrigerant returned to the first refrigerant outflow path is sent to the intercooler via the second refrigerant outflow path, where it exchanges heat with the oxidizing gas before merging with the first refrigerant inflow path. Here, the heat capacity of the oxidizing gas, which is a gas, is sufficiently smaller than the heat capacity of the refrigerant, which is a liquid. Therefore, there is no substantial temperature change in the refrigerant before and after passing through the intercooler. Therefore, the temperature of the refrigerant before passing through the intercooler, the temperature of the refrigerant after passing through the intercooler, and the temperature of the oxidizing gas after passing through the intercooler are always approximately the same.

[0008] From the above, when the flow control valve's diversion ratio is 100%, the temperature of the refrigerant after passing through the fuel cell stack and the temperature of the oxidizing gas after passing through the intercooler will be close to each other. That is, the values ​​detected by the first temperature sensor and the second temperature sensor should be close to each other. Therefore, the cooling system according to the present technology is configured to determine an abnormality when the difference between the values ​​detected by the first temperature sensor and the second temperature sensor is equal to or greater than a first predetermined value. With this configuration, an abnormality in the cooling system can be easily detected simply by comparing the values ​​detected by the two temperature sensors. Note that the first predetermined value used here can be freely set to an appropriate value taking into account factors such as natural heat dissipation that may occur in the refrigerant and measurement errors that may occur in each temperature sensor.

[0009] On the other hand, when the bypass flow ratio is 0 percent, the refrigerant after passing through the radiator is sent to the intercooler via the second refrigerant outflow path without being joined by refrigerant from the bypass path. Therefore, the temperature of the refrigerant after passing through the radiator is close to the temperature of the refrigerant before passing through the intercooler, and is also close to the temperature of the oxidizing gas after passing through the intercooler.

[0010] In light of the above, in a second aspect, the cooling system of the first aspect may further include a third temperature sensor provided in the first refrigerant outflow path and detecting the temperature of the refrigerant after passing through the radiator. In this case, the abnormality monitoring process may include a second determination process that determines an abnormality when the diversion ratio of the flow control valve is 0 percent and the difference between the value detected by the third temperature sensor and the value detected by the second temperature sensor is equal to or greater than a second predetermined value. Even with this configuration, an abnormality in the cooling system can be easily detected simply by comparing the values ​​detected by the two temperature sensors.

[0011] In a third aspect, in the second aspect, the abnormality monitoring process may further include a first identification process in which, when the first determination process determines an abnormality, the flow diversion ratio of the flow control valve is changed to 0 percent and a second determination process is further executed to identify an abnormal part. In this case, the first identification process may identify a part related to the second temperature sensor as the abnormal part when the second determination process also determines an abnormality, and may identify a part related to the first temperature sensor as the abnormal part when the second determination process does not determine an abnormality. With this configuration, an abnormal part in the cooling system can be identified with a relatively simple configuration.

[0012] In a fourth aspect, in the second or third aspect, the abnormality monitoring process may further include a second identification process in which, when the second determination process determines an abnormality, the flow diversion ratio of the flow control valve is changed to 100 percent and the first determination process is further executed to identify the abnormal part. In this case, the second identification process may identify a part related to the second temperature sensor as the abnormal part when the first determination process also determines an abnormality, and may identify a part related to the third temperature sensor as the abnormal part when the first determination process does not determine an abnormality. With this configuration, it is possible to identify an abnormal part in the cooling system with a relatively simple configuration.

[0013] In the cooling system described above, a portion of the refrigerant in the first refrigerant outflow path is sent to the intercooler via the second refrigerant outflow path, regardless of the opening of the flow control valve. In this case, the temperature of the refrigerant before passing through the fuel cell stack approximates the temperature of the refrigerant before passing through the intercooler. As described above, the temperature of the refrigerant before passing through the intercooler approximates the temperature of the oxidizing gas after passing through the intercooler. From the above relationship, the temperature of the refrigerant before passing through the fuel cell stack approximates the temperature of the oxidizing gas after passing through the intercooler, regardless of the opening of the flow control valve.

[0014] In light of the above, in a fifth aspect, in any of the first to fourth aspects, the cooling system may further include a fourth temperature sensor provided in the first refrigerant outflow path that detects the temperature of the refrigerant before passing through the fuel cell stack. In this case, the abnormality monitoring process may include a third determination process that determines an abnormality when the difference between the value detected by the fourth temperature sensor and the value detected by the second temperature sensor is equal to or greater than a third predetermined value, regardless of the diversion ratio set by the flow control valve. With this configuration, an abnormality in the cooling system can be easily detected simply by comparing the values ​​detected by the two temperature sensors. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram illustrating a schematic configuration of a cooling system 10 according to an embodiment and a fuel cell system 100 in which the cooling system 10 is employed. [Figure 2] 4 is a flowchart showing an abnormality monitoring process executed by the control device 32. [Figure 3] 6 is a flowchart showing a first identification process executed by the control device 32. [Figure 4] 10 is a flowchart showing a second identification process executed by the control device 32. DETAILED DESCRIPTION OF THE INVENTION

[0016] A cooling system 10 of this embodiment and a fuel cell system 100 in which the cooling system is employed will be described with reference to the drawings. The cooling system 10 is a system that cools the fuel cell system 100 using a liquid refrigerant such as cooling water. The specific configuration of the fuel cell system 100 is not particularly limited. The fuel cell system 100 may be employed as a power source for a mobile object (for example, an automobile, a bus, a truck, a train, a ship, or an airplane) or as a stationary power source.

[0017] As shown in FIG. 1, the fuel cell system 100 includes a fuel cell stack 102. The fuel cell stack 102 has a structure in which multiple fuel cell units are stacked. The fuel cell stack 102 includes an anode-side supply port (not shown), a cathode-side supply port 104a, an anode-side discharge port (not shown), and a cathode-side discharge port 104b. The anode-side supply port and cathode-side supply port 104a of each fuel cell stack 102 are connected to each of the multiple fuel cell units within the fuel cell stack 102. Each fuel cell stack 102 generates electricity by chemically reacting fuel gas taken in through the anode-side supply port with oxidizing gas taken in through the cathode-side supply port 104a within the multiple fuel cell units. Gas (i.e., off-gas) that has passed through the multiple fuel cell stacks 102 is discharged to the outside through the anode-side discharge port and the cathode-side discharge port 104b.

[0018] 1, the fuel cell system 100 further includes an oxidizing gas supply unit 106. The oxidizing gas supply unit 106 is a unit for supplying air as an oxidizing gas to the fuel cell stack 102. The oxidizing gas supply unit 106 includes an oxidizing gas supply path 108, an inlet valve 110, a compressor 112, an intercooler 114, an off-gas discharge path 116, an outlet valve 118, a flow dividing path 120, and a flow dividing valve 122.

[0019] The oxidizing gas supply path 108 is a path for supplying oxidizing gas (here, air) to the fuel cell stack 102. The oxidizing gas supply path 108 is connected to a cathode-side supply port 104a of the fuel cell stack 102. An inlet valve 110 is provided in the cathode-side supply port 104a of the fuel cell stack 102. A compressor 112 is provided in the oxidizing gas supply path 108, and compresses air taken in from the outside and supplies the air to the fuel cell stack 102. As an example, the compressor 112 is a turbo compressor. An intercooler 114 is provided in the oxidizing gas supply path 108 on the outlet side of the compressor 112. The intercooler 114 cools the air by exchanging heat between the air discharged from the compressor 112 and the refrigerant of the cooling system 10. As a result, the air discharged from the compressor 112 is cooled by the intercooler 114 and then supplied to the cathode supply port 104a of the fuel cell stack 102. Although not particularly limited, the oxidizing gas supply path 108 may further include an air cleaner that removes foreign matter such as dust and dirt from the air taken in from the outside.

[0020] The off-gas discharge path 116 is a path for discharging air off-gas from the fuel cell stack 102. The off-gas discharge path 116 is connected to the cathode-side discharge port 104b of the fuel cell stack 102. The outlet valve 118 is provided in the fuel cell stack 102 at the cathode-side discharge port 104b.

[0021] The shunt path 120 connects the oxidizing gas supply path 108 and the off-gas exhaust path 116 to each other. As an example, in this embodiment, the shunt path 120 is connected to the off-gas exhaust path 116 on the outlet side of the intercooler 114. A shunt valve 122 is provided in the shunt path 120. The inlet valve 110, the outlet valve 118, and the shunt valve 122 are control valves with adjustable openings. The operation (openings) of the inlet valve 110, the outlet valve 118, and the shunt valve 122 are controlled by a control device (not shown). The control device can adjust the supply pressure and supply flow rate of the oxidizing gas supplied to each of the fuel cell stacks 102 by controlling the operation of the compressor 112, the inlet valve 110, the outlet valve 118, and the shunt valve 122.

[0022] Although not shown, the fuel cell system 100 further includes a fuel gas supply unit. The fuel gas supply unit is a unit for supplying hydrogen gas as fuel gas to the fuel cell stack 102.

[0023] Next, the cooling system 10 will be described. As shown in Fig. 1, the cooling system 10 circulates a refrigerant through a fuel cell stack 102 and an intercooler 114. This cools the fuel cell stack 102 and the air passing through the intercooler 114. The cooling system 10 includes a radiator 12, stack cooling circuits 14a, 14b, intercooler cooling circuits 16a, 16b, a bypass path 18, a three-way valve 20, a pump 22, multiple temperature sensors 24, 26, 28, 30, and a control device 32. The radiator 12 is a heat exchanger that exchanges heat between the refrigerant and outside air, and typically cools the refrigerant by dissipating heat.

[0024] The stack cooling circuits 14a, 14b have a first refrigerant outflow path 14a and a first refrigerant return path 14b. The first refrigerant outflow path 14a is provided between the radiator 12 and the fuel cell stack 102, and can send refrigerant from the radiator 12 to the fuel cell stack 102. The first refrigerant return path 14b is provided between the fuel cell stack 102 and the radiator 12, and can return refrigerant from the fuel cell stack 102 to the radiator 12.

[0025] The intercooler cooling circuits 16a, 16b include a second refrigerant outflow path 16a and a second refrigerant return path 16b. The second refrigerant outflow path 16a is provided between the radiator 12 and the intercooler 114 and can send refrigerant from the radiator 12 to the intercooler 114. The second refrigerant outflow path 16a branches off from the first refrigerant outflow path 14a at a first branch point P1. As a result, a portion of the refrigerant in the first refrigerant outflow path 14a is sent to the second refrigerant outflow path 16a at the first branch point P1. The second refrigerant return path 16b is provided between the intercooler 114 and the radiator 12 and can return refrigerant from the intercooler 114 to the radiator 12. The second refrigerant return path 16b merges with the first refrigerant return path 14b at a first junction Q1. As a result, the refrigerant in the second refrigerant return line 16b that has passed through the intercooler 114 merges with the refrigerant in the first refrigerant return line 14b that has passed through the fuel cell stack 102 at the first merge point Q1.

[0026] The bypass path 18 branches off from the first refrigerant return path 14b at a second branch point P2 and merges with the first refrigerant outward path 14a at a second junction point Q2. A three-way valve 20 is provided at the second branch point P2 where the bypass path 18 branches off from the first refrigerant return path 14b. The operation (opening) of the three-way valve 20 is controlled by a control device 32. The control device 32 can adjust the opening of the three-way valve 20 to adjust the diversion ratio to the bypass path 18. Here, the diversion ratio to the bypass path 18 refers to the ratio of the flow rate of the refrigerant circulating through the bypass path 18 to the flow rate of the refrigerant passing through the second branch point P2 in the first refrigerant return path 14b. The pump 22 is provided on the first refrigerant outward path 14a between the second junction point Q2 and the first branch point P1.

[0027] The multiple temperature sensors 24, 26, 28, 30 include a first temperature sensor 24, a second temperature sensor 26, a third temperature sensor 28, and a fourth temperature sensor 30. The first temperature sensor 24 is provided in the first refrigerant return path 14b near the outlet of the fuel cell stack 102, and detects the temperature of the refrigerant after passing through the fuel cell stack 102. As the refrigerant passes through the multiple fuel cell units in the fuel cell stack 102, it absorbs heat from the fuel cell units. Therefore, the detection value S1 by the first temperature sensor 24, i.e., the temperature of the refrigerant after passing through the fuel cell stack 102, approximates the temperature of the fuel cell stack 102.

[0028] The control device 32 determines a target cooling temperature for the fuel cell stack 102. Then, based on the value S1 detected by the first temperature sensor 24, the control device 32 controls the pump 22 to adjust the flow rate of the coolant supplied to the fuel cell stack 102, thereby cooling the fuel cell stack 102 so that the temperature of the fuel cell stack 102 becomes the target cooling temperature.

[0029] The second temperature sensor 26 is provided in the oxidizing gas supply path 108 on the outlet side of the intercooler 114, and detects the temperature of the air after passing through the intercooler 114. The third temperature sensor 28 is provided in the first refrigerant outflow path 14a on the outlet side of the radiator 12, and detects the temperature of the refrigerant after passing through the radiator 12. The fourth temperature sensor 30 is provided in the first refrigerant outflow path 14a near the inlet of the fuel cell stack 102, and detects the temperature of the refrigerant before passing through the fuel cell stack 102. The detection values ​​S1, S2, S3, and S4 of the temperature sensors 24, 26, 28, and 30 are acquired by the control device 32.

[0030] 2-4, a description will be given of the abnormality monitoring process executed by the control device 32. The control device 32 can monitor the cooling system 10 for abnormalities by executing the abnormality monitoring process.

[0031] 2, the control device 32 determines whether the opening degree of the three-way valve 20 is 0 percent (S10). As described above, the control device 32 controls and monitors the opening degree of the three-way valve 20. When the opening degree of the three-way valve 20 is 0 percent, the diversion ratio to the bypass path 18 is 100 percent. Therefore, the refrigerant that has passed through the fuel cell stack 102 is returned to the first refrigerant outflow path 14a without passing through the radiator 12. In the fuel cell system 100 of this embodiment, the opening degree of the three-way valve 20 is set to 0 percent when the fuel cell stack 102 is started up.

[0032] If the answer is YES in step S10, the control device 32 determines whether the difference between the detected value S1 by the first temperature sensor 24 and the detected value S2 by the second temperature sensor 26 is equal to or greater than a first predetermined value A (S12). Here, the difference between the detected value S1 by the first temperature sensor 24 and the detected value S2 by the second temperature sensor 26 refers to the absolute value of the difference between the two detected values ​​S1 and S2. When the opening degree of the three-way valve 20 is 0 percent, a portion of the refrigerant after passing through the fuel cell stack 102 is sent to the intercooler 114 via the second refrigerant outflow path 16a, exchanges heat with air, and then merges with the first refrigerant return path 14b. The heat capacity of gaseous air is significantly smaller than the heat capacity of liquid refrigerant. Therefore, no substantial temperature change occurs in the refrigerant before and after passing through the intercooler 114. Therefore, the temperature of the refrigerant before passing through the intercooler 114, the temperature of the refrigerant after passing through the intercooler 114, and the temperature of the air after passing through the intercooler 114 are always close to each other. Here, the temperature of the refrigerant after passing through the fuel cell stack 102 is detected by the first temperature sensor 24, and the temperature of the air after passing through the intercooler 114 is detected by the second temperature sensor 26. The first predetermined value A can be determined taking into consideration natural heat dissipation that may occur in the refrigerant, measurement errors that may occur in each of the temperature sensors 24, 26, and the like. The first predetermined value A may be a constant value or a variable value that changes according to specific conditions. If the result of step S12 is YES, the control device 32 determines that an abnormality has occurred (S14) and proceeds to the first identification process shown in FIG. 3. If the result of step S12 is NO, the control device 32 proceeds to the process of step S22, which will be described later.

[0033] If the result in step S10 is NO, the control device 32 determines whether the opening degree of the three-way valve 20 is 100 percent (S16). When the opening degree of the three-way valve 20 is 100 percent, the diversion ratio to the bypass path 18 is 0 percent. Therefore, the refrigerant in the first refrigerant return path 14b is returned to the radiator 12 without passing through the bypass path 18. Then, the refrigerant after passing through the radiator 12 is sent to the second refrigerant outward path 16a without being joined by refrigerant from the bypass path 18. In the fuel cell system 100 of this embodiment, when power generation in the fuel cell stack 102 continues and the change in water temperature in the cooling system 10 becomes relatively small, the opening degree of the three-way valve 20 is set to 100 percent.

[0034] If the answer is YES in step S16, the control device 32 determines whether the difference between the value S3 detected by the third temperature sensor 28 and the value S2 detected by the second temperature sensor 26 is equal to or greater than the second predetermined value B (S18). Here, the difference between the value S3 detected by the third temperature sensor 28 and the value S2 detected by the second temperature sensor 26 refers to the absolute value of the difference between the two detected values ​​S2 and S3. As described above, when the three-way valve 20 is open 100 percent, the refrigerant after passing through the radiator 12 is sent to the intercooler 114 through the second refrigerant outflow path 16a without being joined by refrigerant from the bypass path 18. Therefore, the temperature of the refrigerant after passing through the radiator 12 is similar to the temperature of the refrigerant before passing through the intercooler 114 and is also similar to the temperature of the air after passing through the intercooler 114. Here, the temperature of the refrigerant after passing through the radiator 12 is detected by the third temperature sensor 28, and the temperature of the air after passing through the intercooler 114 is detected by the second temperature sensor 26. The second predetermined value B can be determined taking into consideration natural heat dissipation that may occur in the refrigerant, measurement errors that may occur in each of the temperature sensors 26, 28, and the like. The second predetermined value B may be a constant value or a variable value that is changed according to specific conditions. If the answer is YES in step S18, the control device 32 determines that an abnormality has occurred (S20) and proceeds to the second identification process shown in FIG. 4. If the answer is NO in step S18, the control device 32 proceeds to the process of step S22, which will be described later.

[0035] If the determination in step S18 is NO, the control device 32 determines whether the difference between the value S4 detected by the fourth temperature sensor 30 and the value S2 detected by the second temperature sensor 26 is equal to or greater than the third predetermined value C (S24). Here, the difference between the value S4 detected by the fourth temperature sensor 30 and the value S2 detected by the second temperature sensor 26 refers to the absolute value of the difference between the two detected values ​​S2 and S4. In the cooling system 10 of this embodiment, regardless of the opening degree of the three-way valve 20, a portion of the refrigerant in the first refrigerant outflow path 14a is sent to the intercooler 114 via the second refrigerant outflow path 16a, and the remaining portion of the refrigerant in the first refrigerant outflow path 14a is sent to the fuel cell stack 102. Therefore, the temperature of the refrigerant before passing through the fuel cell stack 102 is similar to the temperature of the refrigerant before passing through the intercooler 114. As described above, the temperature of the refrigerant before passing through the intercooler 114 is similar to the temperature of the air after passing through the intercooler 114. Due to the above relationship, the temperature of the refrigerant before passing through the fuel cell stack 102 approximates the temperature of the air after passing through the intercooler 114, regardless of the opening degree of the three-way valve 20. Here, the temperature of the refrigerant before passing through the fuel cell stack 102 is detected by the fourth temperature sensor 30, and the temperature of the air after passing through the intercooler 114 is detected by the second temperature sensor 26. The third predetermined value C can be determined taking into consideration natural heat dissipation that may occur in the refrigerant and measurement errors that may occur in each of the temperature sensors 26, 30. The third predetermined value C may be a constant value or a variable value that changes according to specific conditions. If the answer is YES in step S22, the control device 32 determines that an abnormality has occurred (S24) and ends the abnormality monitoring process. If the answer is NO in step S16, the control device 32 ends the abnormality monitoring process.

[0036] Next, the first identification process shown in Fig. 3 will be described. The first identification process is executed when a YES determination is made in step S12 of Fig. 2. When a YES determination is made in step S12 and an abnormality is detected (S14), the abnormal part is considered to be a part related to the first temperature sensor 24 or a part related to the second temperature sensor 26. By executing the first identification process, the control device 32 identifies one of the part related to the first temperature sensor 24 or the part related to the second temperature sensor 26 as the abnormal part.

[0037] The control device 32 first changes the opening degree of the three-way valve 20 to 100 percent (S28). Then, it determines whether the difference between the value S3 detected by the third temperature sensor 28 and the value S2 detected by the second temperature sensor 26 is equal to or greater than the second predetermined value B (S30). For example, if an abnormality occurs in a portion associated with the first temperature sensor 24, the difference between the value S3 detected by the third temperature sensor 28 and the value S2 detected by the second temperature sensor 26 will be less than the second predetermined value B. On the other hand, if an abnormality occurs in a portion associated with the second temperature sensor 26, the difference between the value S3 detected by the third temperature sensor 28 and the value S2 detected by the second temperature sensor 26 will be equal to or greater than the second predetermined value B. Therefore, if the determination in step S30 is YES, the control device 32 identifies the portion associated with the second temperature sensor 26 as the abnormal portion (S32) and ends the abnormality monitoring process. If the answer is NO in step S30, the control device 32 identifies the part related to the first temperature sensor 24 as the abnormal part (S34) and ends the abnormality monitoring process. The process of step S30 is the same as the process of step S18 described above.

[0038] Next, the second identification process shown in Fig. 4 will be described. The second identification process is executed when the determination in step S18 of Fig. 2 is YES. The second identification process corresponds to the first identification process, except that the combination of the first temperature sensor 24 and the second temperature sensor 26 in the first identification process is changed to the combination of the second temperature sensor 26 and the third temperature sensor 28. That is, by executing the second identification process, the control device 32 identifies either a portion associated with the second temperature sensor 26 or a portion associated with the third temperature sensor 28 as an abnormal portion.

[0039] The control device 32 first changes the opening degree of the three-way valve 20 to 0 percent (S36). Then, it determines whether the difference between the value S1 detected by the first temperature sensor 24 and the value S2 detected by the second temperature sensor 26 is equal to or greater than a first predetermined value A (S38). If the answer is YES in step S38, the control device 32 identifies the part associated with the second temperature sensor 26 as the abnormal part (S40) and ends the abnormality monitoring process. If the answer is NO in step S38, the control device 32 identifies the part associated with the third temperature sensor 28 as the abnormal part (S42) and ends the abnormality monitoring process. The process of step S38 is the same as the process of step S12 described above.

[0040] As described above, in the abnormality monitoring process described above, by comparing the detection values ​​S1, S2, S3, and S4 of two of the temperature sensors 24, 26, 28, and 30, it is possible to easily detect an abnormality in the cooling system 10. Note that the process of step S12 in this specification corresponds to the first determination process in the present technology, the process of step S16 in this specification corresponds to the second determination process in the present technology, and the process of step S22 in this specification corresponds to the third determination process in the present technology. The three-way valve 20 in this specification corresponds to the flow rate adjustment valve in the present technology.

[0041] In the abnormality monitoring process shown in Fig. 2, when the control device 32 determines YES in step S12 and determines that an abnormality has occurred, the process proceeds to a first identification process shown in Fig. 3. In this first identification process, when the control device 32 also determines YES in step S30, the control device 32 identifies a portion related to the second temperature sensor 26 as the abnormal portion (S32). On the other hand, when the control device 32 determines NO in step S30, the control device 32 identifies a portion related to the first temperature sensor 24 as the abnormal portion (S34). With this configuration, it is possible to identify an abnormal portion in the cooling system 10 with a relatively simple configuration.

[0042] In the abnormality monitoring process shown in Fig. 2, when the control device 32 determines YES in step S18 and determines that an abnormality has occurred, the process proceeds to the second identification process shown in Fig. 4. In this second identification process, when the control device 32 also determines YES in step S38, the control device 32 identifies a portion related to the second temperature sensor 26 as the abnormal portion (S40). On the other hand, when the control device 32 determines NO in step S38, the control device 32 identifies a portion related to the third temperature sensor 28 as the abnormal portion (S42). With this configuration, it is possible to identify an abnormal portion in the cooling system 10 with a relatively simple configuration.

[0043] As an example, at least one of the first identification process and the second identification process may be omitted in the abnormality monitoring process shown in Fig. 2. That is, in the abnormality monitoring device shown in Fig. 2, the control device 32 does not necessarily need to identify the abnormal part.

[0044] As an example, step S18 and the processes related thereto may be omitted in the abnormality monitoring process shown in Fig. 2. That is, in the abnormality monitoring process, the second determination process in the present technology may be omitted.

[0045] 2, step S22 and the processes related thereto may be omitted. That is, in the abnormality monitoring process, the third determination process of the present technology may be omitted. In this case, the cooling system 10 of the present embodiment does not necessarily need to include the fourth temperature sensor 30, and may be provided with the three temperature sensors 24, 26, and 28.

[0046] In S12 of FIG. 2, the difference between the detected value S1 by the first temperature sensor 24 and the detected value S2 by the second temperature sensor 26 refers to the absolute value of the difference between the two detected values ​​S1 and S2. However, in another embodiment, the difference between the detected value S1 by the first temperature sensor 24 and the detected value S2 by the second temperature sensor 26 may be the difference between the detected value S1 by the first temperature sensor 24 and the detected value S2 by the second temperature sensor 26 (i.e., detected value S1 - detected value S2, which may be positive or negative). In this case, in S12 of FIG. 2, it is preferable to determine whether "detected value S1 - detected value S2 > any predetermined value" or "detected value S1 - detected value S2 ≧ any predetermined value." This makes it possible to determine an abnormality only when detected value S1 is higher than detected value S2. The same is true for the difference between the detection value S3 by the third temperature sensor 28 and the detection value S2 by the second temperature sensor 26 in S18 of Figure 2, and the difference between the detection value S4 by the fourth temperature sensor 30 and the detection value S2 by the second temperature sensor 26 in S24.

[0047] Although several specific examples have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility either alone or in combination. [Explanation of symbols]

[0048] 10: Cooling system, 12: Radiator, 14: Fuel cell stack, 14a: First refrigerant outflow path, 14b: First refrigerant return path, 16a: Second refrigerant outflow path, 16b: Second refrigerant return path, 18: Bypass path, 20: Three-way valve, 22: Pump, 24: First temperature sensor, 26: Second temperature sensor, 28: Third temperature sensor, 30: Fourth temperature sensor, 32: Control device, 100: Fuel cell system, 102: Fuel cell stack, 104a: Cathode side supply port, 104b: Cathode side discharge port, 106: Oxidizing gas supply unit, 108: Oxidizing gas supply path, 110: Inlet valve, 112: Compressor, 114: Intercooler, 116: Off-gas discharge path, 118: Outlet valve, 120: Diversion path, 122: Diverter valve

Claims

1. A cooling system for a fuel cell that cools a fuel cell stack and an intercooler that cools an oxidizing gas supplied to the fuel cell stack, comprising: A radiator and a stack cooling circuit including a first refrigerant outflow path that sends a refrigerant from the radiator to the fuel cell stack, and a first refrigerant return path that returns the refrigerant from the fuel cell stack to the radiator; an intercooler cooling circuit including a second refrigerant outflow path branching from the first refrigerant outflow path to send the refrigerant to the intercooler, and a second refrigerant return path joining the first refrigerant return path from the intercooler to return the refrigerant; a bypass path that branches off from the first refrigerant return path, bypasses the radiator, and sends the refrigerant to the first refrigerant outward path; a flow rate adjustment valve provided at a branch point where the bypass path branches off from the first refrigerant return path, the flow rate adjustment valve adjusting a flow ratio to the bypass path; a first temperature sensor provided in the first refrigerant return path for detecting the temperature of the refrigerant after passing through the fuel cell stack; a second temperature sensor that detects the temperature of the oxidizing gas after passing through the intercooler; a control device that executes an abnormality monitoring process for monitoring an abnormality in the cooling system; Equipped with the abnormality monitoring process includes a first determination process of determining that an abnormality has occurred when the flow division ratio by the flow rate adjustment valve is 100% and a difference between a detected value by the first temperature sensor and a detected value by the second temperature sensor is equal to or greater than a first predetermined value. Cooling system.

2. a third temperature sensor provided in the first refrigerant outflow path for detecting a temperature of the refrigerant after passing through the radiator; 2. The cooling system of claim 1, wherein the abnormality monitoring process includes a second determination process that determines an abnormality when the flow diversion ratio by the flow control valve is 0 percent and a difference between the detected value by the third temperature sensor and the detected value by the second temperature sensor is equal to or greater than a second predetermined value.

3. the abnormality monitoring process further includes a first identification process in which, when an abnormality is determined in the first determination process, the flow division ratio of the flow rate adjustment valve is changed to 0 percent and the second determination process is further executed to identify an abnormal portion; 3. The cooling system of claim 2, wherein in the first identification process, when the second determination process also determines an abnormality, a part related to the second temperature sensor is identified as the abnormal part, and when the second determination process does not determine an abnormality, a part related to the first temperature sensor is identified as the abnormal part.

4. the abnormality monitoring process further includes a second identification process in which, when an abnormality is determined in the second determination process, the flow division ratio of the flow rate adjustment valve is changed to 100% and the first determination process is further executed to identify an abnormal portion, 3. The cooling system of claim 2, wherein in the second identification process, when the first determination process also determines that an abnormality exists, a part related to the second temperature sensor is identified as the abnormal part, and when the first determination process does not determine that an abnormality exists, a part related to the third temperature sensor is identified as the abnormal part.

5. a fourth temperature sensor provided in the first coolant outflow path for detecting a temperature of the coolant before passing through the fuel cell stack; 5. The cooling system according to claim 1, wherein the abnormality monitoring process includes a third determination process that determines an abnormality when a difference between a detected value by the fourth temperature sensor and a detected value by the second temperature sensor is equal to or greater than a third predetermined value, regardless of the diversion ratio set by the flow control valve.

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