JP2005285489A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately determine the content of abnormality generated in a cooling water circulation circuit, as to a fuel cell system. <P>SOLUTION: The inlet pressure of a pump 20 is detected to compare the detected pressure P with a prescribed reference pressure Pref. As a result of this comparison, when the detected pressure P is larger than the reference pressure Pref, it is determined that the insulating resistance of the cooling water circulation circuit 10 abnormally falls. On the other hand, when the detected pressure P is smaller than the reference pressure Pref, it is determined that the cooling water circulation circuit 10 is closed or water is abnormally leaking. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system, and more particularly to an abnormality determination technique for determining an abnormality in a coolant circulation circuit of a fuel cell system.

  In general, a fuel cell is used as a fuel cell stack in which a plurality of unit fuel cells are stacked. Each cell is configured by sandwiching an electrolyte membrane between a pair of electrodes (anode and cathode) and further sandwiching both sides by a pair of separators. Fuel cells have a suitable operating temperature range that depends on the type of electrolyte membrane. Even if the internal temperature of the fuel cell is higher than its operating temperature range, or conversely, even if the temperature is low, sufficient power generation performance cannot be obtained. For this reason, the separator of each cell is provided with a cooling water flow path for flowing cooling water together with a gas flow path for supplying fuel gas to the anode and a gas flow path for supplying oxidizing gas to the cathode. In addition, the fuel cell is cooled by cooling water, so that the temperature rise due to the reaction heat is suppressed, and the temperature is adjusted to an appropriate operating temperature.

  In a fuel cell system that generates electric power from a fuel cell, for example, an in-vehicle fuel cell system mounted on an electric vehicle, cooling water for cooling the fuel cell is repeatedly reused. Specifically, a cooling water circulation circuit is formed by connecting a cooling water supply pipe connected to the inlet of the cooling water passage of the fuel cell and a cooling water return pipe connected to the outlet of the cooling water passage by a pump. Has been built. For example, a heat exchanger such as a radiator is disposed in the cooling water return pipe, and heat taken by the cooling water from the fuel cell is released to the outside through the heat exchanger.

  In a fuel cell system provided with such a cooling water circulation circuit, when any abnormality occurs in the cooling water circulation circuit, it is necessary to quickly detect the occurrence of the abnormality. This is because if the cooling water circulation circuit cannot supply sufficient cooling water to the fuel cell, the fuel cell may overheat and the power generation performance may be greatly reduced. In addition, when an abnormality occurs in the cooling water circulation circuit, the countermeasure method varies depending on the content of the abnormality. Therefore, it is desired not to simply detect the occurrence of an abnormality but to determine exactly what kind of abnormality has occurred.

With regard to such a demand, Patent Document 1 detects the inlet pressure and the outlet pressure of the cooling water flow path of the fuel cell, and based on the differential pressure between the detected values and the comparison between the detected values and a predetermined reference value. Thus, there is disclosed a technique for identifying an abnormal content and an abnormal part. In this prior art, as an abnormality of the cooling water circulation circuit, a blockage abnormality and a water leakage abnormality are distinguished and distinguished. For example, when the differential pressure between the inlet pressure and the outlet pressure is below a predetermined pressure range, it is determined that a cooling water flow path abnormality has occurred, and both the inlet pressure and the outlet pressure are higher than the respective upper limit values. In this case, it is determined that an abnormal obstruction of the return pipe of the cooling water connected to the outlet side of the cooling water flow path has occurred.
JP 2003-168454 A

  The abnormality in the cooling water circulation circuit includes an abnormality such as a decrease in insulation resistance in addition to the water leakage abnormality and the blockage abnormality assumed in the above-described conventional technology. The cooling water is mixed with impurities such as metal, carbon, and flux that have melted or peeled off from the wall surface of the cooling water circulation circuit, and these impurities increase the conductivity of the cooling water. For this reason, when the concentration of the impurities in the cooling water increases, the insulation resistance of the cooling water circulation circuit decreases, and eventually leakage in the cooling water flow path occurs in the fuel cell. Since electric leakage significantly reduces the power generation performance of the fuel cell, early detection of a decrease in the insulation resistance of the cooling water circulation circuit is desired, as is the case with abnormalities in water leakage and blockage.

  However, it is impossible to discriminate an abnormality in insulation resistance even when the above-described conventional technique is used. When the insulation resistance lowering abnormality occurs, gas is generated in the cooling water circulation circuit by electrolysis of the cooling water. Since this gas increases the overall pressure of the cooling water circulation circuit, the above-described conventional technique determines that the return pipe is abnormally closed by detecting the increase in both the inlet pressure and the outlet pressure of the fuel cell. Obviously, since the countermeasures are different between the blockage abnormality and the insulation resistance lowering abnormality, it is desirable to accurately determine these and take measures according to the abnormality content.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel cell system that can accurately determine the content of an abnormality occurring in a cooling water circulation circuit.

In order to achieve the above object, a first invention provides a fuel cell having a cooling water flow path provided therein,
A cooling water supply pipe connected to the inlet of the cooling water flow path;
A cooling water return pipe connected to the outlet of the cooling water flow path;
A pump for connecting the cooling water supply pipe and the cooling water return pipe to circulate cooling water from the cooling water return pipe to the cooling water supply pipe;
An inlet pressure detecting means for detecting an inlet pressure of the pump;
First abnormality determining means for determining an abnormality in a cooling water circulation circuit comprising the cooling water flow path, the cooling water supply pipe, and the cooling water return pipe based on the detected pressure of the inlet pressure detecting means;
The first abnormality determining means determines that an abnormality in insulation resistance reduction of the cooling water circulation circuit has occurred when the detected pressure is greater than a first reference pressure, and the detected pressure is a value equal to or less than the first reference pressure. When the pressure is smaller than the second reference pressure, the cooling water circulation circuit is determined to be blocked or to have a water leakage abnormality.

Moreover, 2nd invention is equipped with the temperature detection means which detects the temperature of the said cooling water in 1st invention,
The first abnormality determination means sets the first reference pressure and the second reference pressure according to the temperature detected by the temperature detection means.

Further, a third invention is the first or second invention, wherein the load detection means for detecting the load of the pump;
When the first abnormality determining means determines that the cooling water circulation circuit is blocked or leaked, the abnormality of the cooling water circulation circuit is determined in more detail based on the detected load of the load detecting means. 2 an abnormality determination means,
The second abnormality determining means compares the detected load with a predetermined reference load, and determines that the cooling water passage blockage abnormality has occurred when the detected load is greater than the reference load, and the detected load is the reference When the load is lower than the load, it is determined that a water leakage abnormality of the cooling water channel has occurred.

Moreover, 4th invention is equipped with the temperature detection means which detects the temperature of the said cooling water in 3rd invention,
The second abnormality determining means sets the reference load according to the temperature detected by the temperature detecting means.

  In the first aspect of the present invention, when an abnormality in insulation resistance lowering of the cooling water circulation circuit occurs, the pressure of the entire cooling water circulation circuit increases due to the influence of gas generated in the cooling water circulation circuit due to electrolysis of the cooling water. In this case, the inlet pressure of the pump is higher than the normal inlet pressure. In contrast, when a blockage abnormality of the cooling water circulation circuit occurs, the pressure upstream from the blockage point, that is, the pressure from the pump outlet to the blockage point increases, while the pressure from the blockage point downstream, that is, the pressure from the blockage point to the pump inlet. Will decline. In this case, the inlet pressure of the pump is lower than the normal inlet pressure. Further, when a water leakage abnormality occurs in the cooling water circulation circuit, the overall pressure of the cooling water circulation circuit decreases. Also in this case, the inlet pressure of the pump is lower than the normal inlet pressure. As described above, according to the first aspect of the invention, the abnormality of the cooling water circulation circuit is detected by detecting the inlet pressure of the pump and comparing it with a predetermined reference pressure (first reference pressure, second reference pressure). Further, when the detected pressure is higher than the first reference pressure, it can be determined that an abnormality in the insulation resistance of the cooling water circulation circuit has occurred, and the detected pressure has a value equal to or lower than the first reference pressure. When the pressure is smaller than the second reference pressure, it can be determined that the cooling water circulation circuit is clogged or a water leakage abnormality has occurred.

  The pressure of the cooling water circulation circuit varies with the temperature of the cooling water, and the inlet pressure of the pump also varies with the temperature of the cooling water. According to the second aspect of the invention, the first reference pressure and the second reference pressure are set according to the temperature of the cooling water, so that the cooling is performed even during transient operation in which the temperature of the cooling water is changing. It is possible to accurately detect an abnormality in the water circulation circuit and accurately determine whether the abnormality occurring in the cooling water circulation circuit is an insulation resistance lowering abnormality, a blockage or a water leakage abnormality.

  In the third aspect of the present invention, when an abnormality in the cooling water circulation circuit occurs, the pressure on the pump outlet side increases and the pressure on the pump inlet side decreases, so the pump load increases more than the normal load. become. On the other hand, when a water leakage abnormality occurs in the cooling water circulation circuit, the pressure on both the pump outlet side and the pump inlet side is reduced, so that the pump load is lower than the normal load. As described above, according to the third aspect of the present invention, when the detected load is greater than the reference load, it is determined that a cooling channel blockage abnormality has occurred by detecting the pump load and comparing it with a predetermined reference load. When the detected load is equal to or lower than the reference load, it can be determined that a cooling water channel leakage abnormality has occurred.

  When the flow rate of the cooling water is constant, the load of the pump changes depending on the viscosity of the cooling water in the cooling water circulation circuit, and the viscosity of the cooling water changes depending on the temperature of the cooling water. For this reason, the load of the pump differs depending on the temperature of the cooling water. According to the fourth aspect of the invention, the reference load is set according to the temperature of the cooling water, so that an abnormality occurring in the cooling water circulation circuit can be prevented from occurring even during a transient operation in which the temperature of the cooling water is changing. It is possible to accurately determine whether there is an abnormality in water leakage.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4.
The fuel cell system of the present invention can be applied to, for example, a vehicle fuel cell system mounted on a vehicle. However, it is of course possible to apply the fuel cell system to other uses.

  FIG. 1 is a schematic configuration diagram of a fuel cell system as Embodiment 1 of the present invention. As shown in the figure, the fuel cell system includes a fuel cell 2. The fuel cell 2 is configured as a fuel cell stack in which a plurality of unit fuel cells are stacked. Each cell is configured by sandwiching an electrolyte membrane such as a solid polymer membrane between an anode and a cathode which are catalyst electrodes, and further sandwiching both sides by a pair of separators (in the figure, the cell, the electrolyte membrane, the anode, The illustration of the cathode and separator is omitted). The separator is provided with a gas flow path for supplying fuel gas to the anode, a gas flow path for supplying oxidizing gas to the cathode, and a cooling water flow path 12 for flowing cooling water (in the figure). In FIG. 5, only the cooling water flow path 12 is schematically shown).

  A cooling water supply pipe 14 connected to the inlet side of the cooling water flow path 12 and a cooling water return pipe 16 connected to the outlet side of the cooling water flow path 12 are connected to the fuel cell 2. The cooling water supply pipe 14 and the cooling water return pipe 16 are connected by a pump 20, whereby the cooling water circulation circuit 10 including the cooling water supply pipe 14, the cooling water flow path 12, and the cooling water return pipe 16 is configured. By pumping the cooling water from the cooling water return pipe 16 side to the cooling water supply pipe 14 side by the pump 20, the cooling water circulates in the cooling water circulation circuit 10 while cooling the fuel cell 2 through the cooling water flow path 12. Keep doing. The pump 20 is an electric pump driven by a motor 22, and the flow rate of the cooling water can be controlled by controlling the rotation speed of the motor 22.

  In the middle of the cooling water return pipe 16, a radiator 24 for cooling the cooling water heated through the fuel cell 2 is provided. A bypass pipe 18 is provided so as to bypass the radiator 24. The downstream end of the bypass pipe 18 is connected to the cooling water return pipe 16 via a three-way switching valve 26, and the flow path of the cooling water is changed from the radiator 24 side to the bypass pipe 18 side by switching the port of the three-way switching valve 26. Switchable. When the temperature of the fuel cell 2 has not risen to the proper operating temperature as in cold start, the three-way switching valve 26 is switched to the bypass pipe 18 side, and the temperature of the fuel cell 2 rises and cooling is required. The three-way switching valve 26 is switched to the radiator 24 side.

  The fuel cell system also includes an ECU (Electronic Control Unit) 30 as a control device for controlling the operation of the entire system. In the present embodiment, the ECU 30 functions as an abnormality determination unit that determines an abnormality of the cooling water circulation circuit 10 as described later. On the input side of the ECU 30, a pressure sensor 32 that is disposed at the downstream end of the cooling water return pipe 16 and detects the inlet pressure of the pump 20, an ammeter 34 that measures the current flowing through the motor 22, and the cooling water return pipe 16 is connected to a temperature sensor 36 that is disposed at the upstream end of 16 and detects the outlet temperature of the fuel cell 2. Further, a display device (meter / display) 40 for displaying a processing result by the ECU 30 is connected to the output side of the ECU 30.

  In the system of the type that circulates the cooling water like the present fuel cell system, some abnormality may occur in the cooling water circulation circuit 10. The abnormality of the cooling water circulation circuit 10 includes a blockage abnormality in which the cooling water circulation circuit 10 is blocked due to clogging of dust, a leakage abnormality in which the cooling water leaks from the cooling water circulation circuit 10 due to hole opening or poor adhesion, etc., and conductivity in the cooling water. The insulation resistance of the cooling water circulation circuit 10 decreases due to an increase in the concentration of the conductive impurities, and there is an abnormality in the insulation resistance decrease that gas is generated by electrolysis of the cooling water in the cooling water circulation circuit 10. Even if any abnormality such as a blockage abnormality, a water leakage abnormality, or an insulation resistance lowering abnormality occurs, it becomes impossible to supply the target flow rate of cooling water to the fuel cell 2 and the fuel cell 2 is overheated. In particular, when an abnormality in insulation resistance lowering occurs, there is a possibility that electric leakage to the cooling water passage 12 occurs in the fuel cell 2. If such an abnormality is left unattended, the power generation performance of the fuel cell 2 is greatly reduced, which is not preferable. Therefore, in this fuel cell system, the abnormality of the cooling water circulation circuit 10 is detected quickly and reliably, and the abnormality determination process described below is performed by the ECU 30 in order to accurately determine the content of the abnormality. Yes.

  FIG. 2 is a flowchart showing a process flow when the ECU 30 performs the abnormality determination process. During operation of the fuel cell system, the ECU 30 receives detection signals from the pressure sensor 32, the ammeter 34, and the temperature sensor 36, and performs abnormality determination based on these detection signals. In the routine of FIG. 2, first, in the first step, step 100, the detected temperature T from the temperature sensor 36 and the detected pressure P from the pressure sensor 32 are read. The detected temperature T indicates the temperature of the cooling water at the outlet of the fuel cell 2 at the current time, and the detected pressure P indicates the inlet pressure of the pump 20 at the current time.

  In step 102, based on the detected temperature T read in step 100, the normal inlet pressure of the pump 20 is calculated as a reference pressure Pref. In the present embodiment, the reference pressure Pref is calculated from a map using the detected temperature T shown in FIG. 3 as a parameter. The pressure in the cooling water circulation circuit 10 varies depending on the temperature of the cooling water, and the pressure increases as the temperature increases. The same applies to the inlet pressure of the pump 20. For this reason, the map shown in FIG. 3 is set so that the reference pressure Pref increases as the detected temperature T increases.

  In the next step 104, the detected pressure P read in step 100 is compared with the reference pressure Pref calculated in step 102. The abnormality of the cooling water circulation circuit 10 is detected by comparing the detected pressure P and the reference pressure Pref, and at the same time, the first stage of the abnormality content is also determined.

  First, when the detected pressure P matches the reference pressure Pref as a result of the comparison in step 104, it is determined that there is no abnormality in the cooling water circulation circuit 10. In this case, the process returns to step 100 and the processing from step 100 to step 104 is repeated again. Each time the detected pressure P and the detected temperature T are detected in step 100, and the reference pressure Pref is updated in step 102, it is updated to the latest value.

  On the other hand, if the detected pressure P does not match the reference pressure Pref as a result of the comparison in step 104, it is determined that the cooling water circulation circuit 10 is abnormal. However, the process differs depending on whether the detected pressure P is greater than or less than the reference pressure Pref. In the former case, the process proceeds to step 106, and in the latter case, the process proceeds to step 110.

  When the routine proceeds to step 106, that is, when the detected pressure P is greater than the reference pressure Pref, it is determined that an abnormality in the insulation resistance of the cooling water circulation circuit 10 has occurred. When an insulation resistance lowering abnormality occurs, the overall pressure of the cooling water circulation circuit 10 increases due to the influence of gas generated by electrolysis of the cooling water, and the inlet pressure of the pump 20 also increases from the normal inlet pressure. On the other hand, when a blockage abnormality occurs, the pressure from the outlet of the pump 20 to the blockage point increases, while the pressure from the blockage point to the pump 20 inlet decreases, so the inlet pressure of the pump 20 is normal. Lower than inlet pressure. Further, when a water leakage abnormality occurs, the overall pressure of the cooling water circulation circuit 10 decreases, so that the inlet pressure of the pump 20 is lower than the normal inlet pressure. Therefore, the insulation resistance drop abnormality can be distinguished from the blockage abnormality and the water leakage abnormality by the difference in the magnitude relationship between the detection pressure P and the reference pressure Pref.

  In step 108, an alarm signal is output from the ECU 30 to the display device 40 based on the determination result in step 106. The display device 40 displays an abnormal failure mode corresponding to the content of the alarm signal from the ECU 30 to notify the user of the occurrence of the abnormality and its content. Here, for example, “leakage alarm” is displayed on the display device 40.

  As a result of the comparison in step 104, when the process proceeds to step 110, that is, when the detected pressure P is smaller than the reference pressure Pref, first, the detected temperature T from the temperature sensor 36 and the detected current I from the ammeter 34 are read. . The detected temperature T indicates the temperature of the cooling water at the outlet of the fuel cell 2 at the present time. The detection current I indicates the current flowing through the motor 22 at the present time, and this corresponds to the load of the pump 20 at the current time. The larger the load on the pump 20, the larger the current flowing through the motor 22, and the smaller the load on the pump 20, the smaller the current flowing through the motor 22.

  In the next step 112, based on the detected temperature T read in step 110, a reference current Iref corresponding to a normal motor current is calculated. In the present embodiment, the reference current Iref is calculated from a map using the detected temperature T shown in FIG. 4 as a parameter. When the flow rate of the cooling water is constant, the load of the pump 20 varies depending on the viscosity of the cooling water in the cooling water circulation circuit 10, and the viscosity of the cooling water in the cooling water circulation circuit 10 varies depending on the temperature of the cooling water. Specifically, as the temperature of the cooling water rises and the viscosity of the cooling water in the cooling water circulation circuit 10 decreases, the load on the pump 20 decreases accordingly. As a result, the current flowing through the motor 22 is also reduced. For this reason, the map shown in FIG. 4 is set so that the reference current Iref decreases as the detected temperature T increases.

  In step 114, the detected current I read in step 100 is compared with the reference current Iref calculated in step 112. By comparing the detection current I and the reference current Iref, the second stage determination of the abnormality content is performed.

  If the detected current I is larger than the reference current Iref as a result of the comparison in step 114, it is determined that a clogging abnormality of the cooling water circulation circuit 10 has occurred (step 116). On the other hand, if the detected current I is less than or equal to the reference current Iref, it is determined that a water leakage abnormality has occurred in the cooling water circulation circuit 10 (step 120). When a blockage abnormality occurs, the pressure on the outlet side of the pump 20 increases and the pressure on the inlet side of the pump 20 decreases, so the load on the pump 20 increases more than the normal load. On the other hand, when a water leakage abnormality occurs, the pressure on both the outlet side and the inlet side of the pump 20 is reduced, so that the load on the pump 20 is lower than the normal load. Therefore, the blockage abnormality and the water leakage abnormality can be distinguished by the difference in magnitude between the detection current I and the reference current Iref.

  When it is determined in step 116 that the cooling water circulation circuit 10 is abnormally closed, an alarm signal corresponding to the determination result is output from the ECU 30 to the display device 40. Upon receiving this alarm signal, for example, “blocking alarm” is displayed on the display device 40 (step 118). Similarly, if it is determined in step 120 that the coolant circulation circuit 10 is abnormal in water leakage, an alarm signal from the ECU 30 is received and, for example, “water leakage alarm” is displayed on the display device 40 (step 122).

  By executing the above abnormality determination processing routine, the abnormality of the cooling water circulation circuit 10 is quickly detected, and whether the abnormality is a blockage abnormality, a water leakage abnormality, or an insulation resistance lowering abnormality. Whether or not there is an abnormality is accurately determined. Therefore, according to the present fuel cell system, when any abnormality occurs in the coolant circulation circuit 10, the user can quickly take appropriate measures according to the abnormality internal use.

  In the above embodiment, the “first abnormality determination means” of the first invention and the second invention is realized by the execution of the processing of steps 100 to 108 by the ECU 30. Further, the “second abnormality determination means” of the third and fourth aspects of the present invention is realized by the execution of the processing of steps 110 to 122 by the ECU 30.

Others.
While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the following modifications may be made.

  In the above embodiment, the temperature sensor 36 is provided at the outlet of the fuel cell 2. However, since the temperature sensor 36 detects a reference temperature for setting the reference pressure Pref and the reference current Iref, the cooling water circulation circuit 10 is provided. The position where the temperature sensor 36 is provided is not limited as long as the coolant temperature in the coolant circulation circuit 10 can be detected.

  Further, the reference pressure Pref and the reference current Iref can be fixed values. The cooling water temperature in the cooling water circulation circuit 10 changes greatly during a transient operation such as during startup, but the cooling water becomes a substantially constant temperature during steady operation. Thus, if the abnormality determination is performed only in a situation where the cooling water temperature is substantially constant, accurate abnormality determination can be performed even if the reference pressure Pref and the reference current Iref are fixed values.

  Further, the reference pressure Pref is not limited to one value, and may have a certain range. That is, a pressure range determined by the upper limit pressure value (first reference pressure) and the lower limit pressure value (second reference pressure) may be set as the reference pressure Pref. This is because it is assumed that a certain amount of error is included in the normal inlet pressure. In this case, if the detected pressure P falls within the pressure range of the reference pressure Pref, it can be determined that there is no abnormality, and if the detected pressure P exceeds the upper limit pressure value of the reference pressure Pref, it is determined that there is an abnormality in insulation resistance reduction. When the detected pressure P is lower than the lower limit pressure value of the reference pressure Pref, it can be determined that the blockage or the water leakage is abnormal.

  In the above embodiment, the ammeter 34 is provided as means for detecting the load of the pump 20 and the current flowing through the motor 22 is measured by the ammeter 34. However, a physical quantity corresponding to the load of the pump 20 is detected. What is necessary is not necessarily limited to the ammeter 34. For example, the rotational speed of the pump 20 may be detected by a rotational speed sensor, and the detected rotational speed may be used as a load of the pump 20.

1 is a diagram showing a schematic configuration of a fuel cell system as an embodiment of the present invention. It is a flowchart of the abnormality determination processing routine performed in the embodiment of the present invention. It is a graph which shows the relationship between the temperature of a cooling water, and the inlet pressure of a pump. It is a graph which shows the relationship between the temperature of a cooling water, and the electric current which flows into the drive motor of a pump.

Explanation of symbols

2 Fuel cell 10 Cooling water circulation circuit 12 Cooling water flow path 14 Cooling water supply pipe 16 Cooling water return pipe 18 Bypass pipe 20 Pump 22 Motor 24 Radiator 26 Three-way selector valve 30 ECU
32 Pressure sensor 34 Ammeter 36 Temperature sensor 40 Display device

Claims (4)

A fuel cell having a cooling water flow path therein;
A cooling water supply pipe connected to the inlet of the cooling water flow path;
A cooling water return pipe connected to the outlet of the cooling water flow path;
A pump for connecting the cooling water supply pipe and the cooling water return pipe to circulate cooling water from the cooling water return pipe to the cooling water supply pipe;
An inlet pressure detecting means for detecting an inlet pressure of the pump;
First abnormality determining means for determining an abnormality in a cooling water circulation circuit composed of the cooling water flow path, the cooling water supply pipe, and the cooling water return pipe based on the detected pressure of the inlet pressure detecting means;
The first abnormality determining means determines that an abnormality in insulation resistance reduction of the cooling water circulation circuit has occurred when the detected pressure is greater than a first reference pressure, and the detected pressure is a value equal to or less than the first reference pressure. The fuel cell system is characterized in that when the pressure is smaller than the second reference pressure, the cooling water circulation circuit is determined to be blocked or leaked. Comprising temperature detecting means for detecting the temperature of the cooling water,
2. The fuel cell system according to claim 1, wherein the first abnormality determination unit sets the first reference pressure and the second reference pressure in accordance with a temperature detected by the temperature detection unit. Load detecting means for detecting the load of the pump;
When the first abnormality determining means determines that the cooling water circulation circuit is blocked or leaked, the abnormality of the cooling water circulation circuit is determined in more detail based on the detected load of the load detecting means. 2 an abnormality determination means,
The second abnormality determining means compares the detected load with a predetermined reference load, determines that the cooling water passage blockage abnormality has occurred when the detected load is greater than the reference load, and the detected load is the reference 3. The fuel cell system according to claim 1, wherein when the load is equal to or lower than the load, it is determined that an abnormality in water leakage of the cooling water channel has occurred. Comprising temperature detecting means for detecting the temperature of the cooling water,
4. The fuel cell system according to claim 3, wherein the second abnormality determination unit sets the reference load according to a temperature detected by the temperature detection unit. 5.

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