JP6802984B2 - Fuel cell cooling system - Google Patents

Description

The present invention relates to a fuel cell cooling system.

The fuel cell is generally used as a fuel cell stack in which a plurality of fuel cell cells (hereinafter, also referred to as cells) are stacked. Each cell is configured by sandwiching a MEA composed of an electrolyte membrane and an anode (fuel electrode) and a cathode (air electrode) bonded to both sides thereof 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 it is low, sufficient power generation performance cannot be obtained. Therefore, the separator of each cell is provided with a gas flow path for supplying fuel gas to the anode, a gas flow path for supplying oxidation gas to the cathode, and a cooling water flow path for flowing cooling water. By cooling the fuel cell with cooling water, the temperature rise due to the reaction heat is suppressed, and the temperature is adjusted to an appropriate operating temperature.

The cooling water for cooling the fuel cell is usually reused repeatedly. Therefore, the fuel cell system is provided with a cooling water circulation flow path for circulating and supplying the cooling water to the fuel cell. For example, the cooling water circulation flow path described in Patent Document 1 below includes a stack flow path for flowing cooling water to a fuel cell, a radiator flow path connected to the stack flow path and having a radiator, and a bypass flow path bypassing the radiator. It is provided with a road, and a three-way valve for switching the flow ratio of the cooling water flowing through the radiator flow path or the bypass flow path is provided.

Japanese Unexamined Patent Publication No. 2005-285489

By the way, when an abnormality such as a cooling water leak occurs in the cooling water circulation flow path, it is necessary to promptly detect the occurrence. Conventionally, although a technique for detecting such a cooling water leak has been proposed, it is not possible to determine which of the stack flow path, the radiator flow path, and the bypass flow path of the cooling water circulation flow path has an abnormality. It was difficult to identify the location of the abnormality.

Therefore, an object of the present invention is to provide a fuel cell cooling system capable of easily identifying the location of an abnormality when an abnormality occurs in the cooling water circulation flow path.

The fuel cell cooling system according to the present invention includes a fuel cell, a cooling water circulation flow path for circulating cooling water for cooling the fuel cell, and a cooling water pump provided in the cooling water circulation flow path for circulating cooling water. In the fuel cell system, the cooling water circulation flow path has a stack flow path for flowing cooling water through the fuel cell and a radiator that releases the heat of the cooling water to the outside, and is cooled between the radiator and the fuel cell. The radiator flow path connected to both ends of the stack flow path so that water circulates, and the cooling water that branches from one end of both ends of the stack flow path and joins the other end, bypassing the radiator flow path. A three-way valve, which is provided at one end of both ends of the stack flow path and is provided at one end of both ends of the stack flow path to adjust the flow ratio of the cooling water flowing into the radiator flow path and the bypass flow path, and a cooling water pump. It has an estimated flow rate estimated based on the number of rotations and the temperature of the cooling water, a control unit that stores a map for determining a flow path abnormality state based on the power consumption of the cooling water pump, and a radiator. When cooling water is flowing through both the flow path and the bypass flow path, if the control unit determines that the flow path is abnormal, the flow path abnormality is resolved by closing the valve on the bypass flow path side of the three-way valve. When this is done, it is determined that the bypass flow path is abnormal, and when the flow path abnormality is resolved by closing the valve on the radiator flow path side of the three-way valve, it is determined that the radiator flow path is abnormal, and the flow is controlled by controlling the opening of the three-way valve. When the path abnormality state is not resolved, it is determined that the stack flow path is abnormal.

According to this configuration, the flow path abnormality state is determined based on the map based on the relationship between the estimated flow rate and the power consumption, and the flow path abnormality state is eliminated by closing the valve on the radiator flow path side or the bypass flow path side of the three-way valve. By determining whether or not, it is possible to determine which of the stack flow path, the bypass flow path, and the radiator flow path of the cooling water circulation flow path has an abnormality. As a result, it is possible to easily identify the location where an abnormality occurs in the cooling water circulation flow path.

According to the present invention, it is possible to provide a fuel cell cooling system that can easily identify the location of an abnormality when an abnormality occurs in the cooling water circulation flow path.

It is a schematic block diagram of the fuel cell cooling system in this embodiment. It is a flowchart which shows an example of the abnormality occurrence location identification flow. It is a graph which shows the map based on the relationship between the estimated flow rate of a pump, and power consumption. It is a flowchart which shows an example of fail-safe processing when a bypass flow path is blocked. It is a flowchart which shows an example of the fail-safe processing when a radiator flow path is blocked. It is a graph for demonstrating the limit start temperature and the limit rate. It is a figure for demonstrating the pump rotation speed calculation method and the three-way valve target opening degree calculation method.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following description of the preferred embodiment is merely an example, and is not intended to limit the present invention, its application, or its use.

The fuel cell cooling system 1 of the present embodiment is mounted on a vehicle, for example. As shown in FIG. 1, the fuel cell cooling system 1 includes a fuel cell stack 10 (fuel cell), a circulation flow path 20 (cooling water circulation flow path), a radiator 30, temperature sensors 41 and 42, and a three-way valve 50. A water pump 60 (cooling water pump), an intercooler 70, an ECU 100 (control unit), and the like are provided.

The fuel cell stack 10 has a stack structure in which a plurality of fuel cell cells that generate electric power by utilizing an electrochemical reaction between hydrogen and oxygen are stacked. Each fuel cell includes an electrolyte membrane, an anode and a cathode. The anode and cathode are electrode catalyst layers carrying a catalyst such as platinum or a platinum alloy. The electrolyte membrane constitutes a membrane electrode assembly (MEA) together with an anode and a cathode bonded to both sides thereof. The fuel cell has a configuration in which the MEA is sandwiched between a pair of separators.

The circulation flow path 20 is a flow path for circulating the cooling water to the outside of the fuel cell stack 10 so that the cooling water for cooling the fuel cell flows out of the fuel cell stack 10 and returns to the fuel cell stack 10. The circulation flow path 20 connects the cooling water outlet at the lower part of the drawing and the cooling water inlet at the upper part of the drawing of the fuel cell stack 10. As the cooling water, for example, a mixed solution of ethylene glycol and water can be used in order to prevent freezing at a low temperature.

The circulation flow path 20 includes a stack flow path SL, a bypass flow path BL, and a radiator flow path RL. The stack flow path SL is a flow path connected to the inlet side and the outlet side of the fuel cell stack 10 in order to allow cooling water to flow through the fuel cell stack 10. Both ends of the stack flow path SL are connected to both ends of the bypass flow path BL (in other words, both ends of the radiator flow path RL). The radiator flow path RL has a radiator 30 that releases the heat of the cooling water to the outside, and is connected to both ends of the stack flow path SL so that the cooling water is circulated between the radiator 30 and the fuel cell stack 10. Is. The bypass flow path BL is a flow path for branching from one end of both ends of the stack flow path SL, merging with the other end, bypassing the radiator flow path RL, and flowing cooling water. Note that, in FIG. 1, the regions shown by the stack flow path SL, the bypass flow path BL, and the radiator flow path RL are shown as schematic views, and are not limited to the regions shown in FIG.

The radiator 30 provided in the radiator flow path RL has a function of releasing the heat of the cooling water to the outside by heat exchange with the outside air. As shown in FIG. 1, in addition to the configuration in which the radiator 30 is provided in the radiator flow path RL, a sub-radiator 35 that assists the heat exchange function by the radiator 30 may be provided.

The bypass pipe 21 that bypasses the radiator 30 and allows the cooling water to flow is one end of both ends of the stack flow path SL (that is, the connection point between the stack flow path SL and the radiator flow path RL) (upstream side of the radiator flow path RL). This is a flow path that branches from the radiator flow path RL and joins the other end (downstream side of the radiator flow path RL) of both ends of the stack flow path SL. In other words, the bypass pipe 21 branches from the radiator flow path RL at the branch position on the upstream side of the cooling water flow from the radiator 30, and is connected to the radiator flow path RL at the confluence position on the downstream side of the cooling water flow from the radiator 30. It is a flow path. By providing the bypass pipe 21 in this way and controlling the opening degree of the three-way valve 50 described later, the cooling water can be circulated between the stack flow path SL and the bypass pipe 21 by bypassing the radiator flow path RL. The bypass pipe 21 is provided with a cooling water passage connected in parallel to the bypass pipe 21, and an ion exchanger 75 serving as an ion adsorption means is arranged in the cooling water passage. The ion exchanger 75 is filled with, for example, an ion exchange resin. Since the cooling water comes into contact with the fuel cell in the fuel cell stack 10, ions are adsorbed and removed from the cooling water in the ion exchanger 75 to suppress an increase in the conductivity of the cooling water. In this specification, the flow path including the bypass pipe 21 and the pipe passing through the ion exchanger 75 will be referred to as a bypass flow path BL.

A three-way valve 50 is provided at a branch point (that is, one end of both ends of the stack flow path SL) that branches to the bypass flow path BL on the upstream side of the radiator flow path RL. In other words, the three-way valve 50 is provided on one side (upstream side of the radiator flow path RL) of the connection positions between the radiator flow path RL and the stack flow path SL. The three-way valve 50 is a valve device that adjusts the flow rate ratio of the cooling water flowing through the radiator flow path RL and the cooling water flowing through the bypass flow path BL. The three-way valve 50 has an inlet for cooling water flowing in from the upstream side, and has a first outlet for discharging the cooling water to the radiator 30 side and a second outlet for discharging the cooling water to the bypass pipe 21 side. It has a structure in which the opening degrees of the first outlet and the second outlet can be adjusted respectively.

The water pump 60 is a circulation pump for circulating cooling water in the circulation flow path 20. The water pump 60 is arranged on the downstream side of the cooling water flow from the confluence point of the bypass flow path BL on the downstream side of the radiator flow path RL. Specifically, the water pump 60 is arranged on the downstream side of the confluence of the bypass flow paths BL on the downstream side of the radiator flow path RL and on the upstream side of the fuel cell stack 10. The water pump 60 can be, for example, a pump device that rotates an impeller by driving a motor 61 in a pump housing.

The circulation flow path 20 is provided with a cooling water passage that bypasses the fuel cell stack 10, and an intercooler 70 is arranged in this cooling water passage. The intercooler 70 is a heat exchanger that exchanges heat between the air supplied to the fuel cell stack 10 and the cooling water, and adjusts the temperature of the air supplied to the fuel cell stack 10 to a suitable temperature. ..

The circulation flow path 20 is provided with temperature sensors 41 and 42, which are temperature detecting means for detecting the temperature of the cooling water. The temperature sensor 41 (radiator outlet temperature sensor) is arranged on the downstream side of the cooling water flow from the radiator 30, and the temperature sensor 42 (stack outlet temperature sensor) is arranged on the downstream side of the cooling water flow from the fuel cell stack 10. Then, the temperature information of the cooling water detected by the temperature sensors 41 and 42 is output to the ECU 100.

The ECU 100 controls the operation of various devices in the system, and is composed of a computer system (not shown). Such a computer system is provided with a CPU, ROM, RAM, HDD, input / output interface, etc., and various control operations can be realized by the CPU reading and executing various control programs recorded in the ROM. It has become. For example, the ECU 100 inputs information on the amount of heat generated or generated by the fuel cell output by the fuel cell stack 10, and temperature information output by the temperature sensors 41 and 42, and based on these input information, the three-way valve 50 and water The pump 60 is driven and controlled. Further, the ECU 100 monitors and stores the power consumption of the water pump 60, for example. Further, the ECU 100 controls the opening degree of the three-way valve 50 based on, for example, the temperature information of the cooling water at the outlet of the fuel cell stack 10 detected by the temperature sensor 42. As a method of controlling the opening degree of the three-way valve 50, for example, when the temperature of the cooling water detected by the temperature sensor 42 is higher than a predetermined value, the three-way valve 50 is controlled so as to flow the cooling water to the radiator 30 to cool it. On the other hand, if the value is lower than the predetermined value, the three-way valve 50 is controlled so that the cooling water flows through the bypass flow path BL including the ion exchanger 75. Further, for example, the ECU 100 detects the conductivity of the circulation flow path 20 by a predetermined conductivity detecting means (not shown), and when the conductivity is lower than the predetermined value, the bypass flow path BL including the ion exchanger 75 is included. The three-way valve 50 is controlled so as to reduce the conductivity by flowing cooling water through the air. The opening degree adjustment of the three-way valve 50 in this embodiment will be described later with reference to FIG.

Further, the ECU 100 stores a map based on the rotation speed of the water pump 60 and the temperature of the cooling water (or a calculation formula showing the relationship between the rotation speed of the water pump 60 and the cooling water). The ECU 100 calculates an estimated value of the power consumption of the water pump 60 based on this map (or calculation formula).

Further, as shown in FIG. 3A, the ECU 100 has an estimated flow rate of cooling water pumped by the water pump 60 and the water pump 60 when a turbo type (impeller) pump is used as the water pump 60. A map based on the relationship between power consumption (or a calculation formula showing the relationship between estimated flow rate and power consumption) is stored. The estimated flow rate shown in FIG. 3A can be estimated based on, for example, the rotation speed (rpm) of the water pump 60. Based on the map of FIG. 3 (A) (horizontal axis is estimated flow rate (rpm), vertical axis is power consumption (w)), the normal estimated flow rate-power consumption line shown in FIG. 3 (A) (hereinafter, estimated). In the case of a region above the line R1), in other words, when the measured value of the power consumption of the water pump 60 at a predetermined flow rate is equal to or higher than the estimated line R1 shown in FIG. 3 (A), it is normal. (No flow path blockage, no flow path leakage) can be determined, and if it is less than the estimated line R1 shown in FIG. 3A, it can be determined to be abnormal (flow path blockage, cooling water leakage). ..

Further, as shown in FIG. 3B, the relationship between the estimated flow rate of the cooling water pumped by the water pump 60 and the power consumption of the water pump 60 when a positive displacement pump is used as the water pump 60 in the ECU 100. A map based on (or a calculation formula showing the relationship between the estimated flow rate and the power consumption) is also stored. Similar to FIG. 3 (A), the horizontal axis shown in FIG. 3 (B) shows the estimated flow rate (rpm), and the vertical axis shows the power consumption (w). Based on the map shown in FIG. 3 (B), when the region is above the normal estimated flow rate-power consumption line (hereinafter, also referred to as estimated line R2) shown in FIG. 3 (B), in other words, it is predetermined. When the measured value of the power consumption of the water pump 60 at the flow rate is equal to or higher than the estimation line R2 shown in FIG. 3B, it can be determined that there is an abnormality (flow path obstruction, cooling water leakage), and FIG. If it is less than the estimated line R2 shown in (B), it can be determined to be normal (no flow path obstruction, no flow path leakage).

In the present embodiment, the rotation speed target value of the water pump 60 (hereinafter, also referred to as “pump” as shown) and the target opening degree of the three-way valve 50 are calculated as follows. As shown in FIG. 7, first, the rotation speed target value of the pump is calculated, and a control signal is output to the pump based on the rotation speed target value of the pump (signal A1 shown in FIG. 7). The power consumption and rotation speed of the pump are input from the pump to the ECU (signal A2 shown in FIG. 7). The input power consumption and rotation speed are stored in the ECU, and the flow path blockage determination (described later) is performed based on the stored information. The ECU calculates the target opening degree of the three-way valve 50 based on the result of the flow path blockage determination, converts the target opening degree into a drive signal, and then controls the opening degree of the three-way valve 50. Further, the ECU calculates the pump rotation speed target value based on the flow path blockage determination and outputs it to the pump.

Next, a flow for identifying an abnormality occurrence location executed in the above-mentioned fuel cell cooling system will be described. FIG. 2 is a flowchart showing an example of an abnormality occurrence location identification flow. The determination process for identifying the location of the abnormality, which will be described below, is executed, for example, at the time of starting, at the time of replacing parts, or at the timing of constant operation.

First, in step S110, it is determined whether or not there is other diagnostic information (for example, sensor disconnection short circuit including whether or not the sensor is operating normally), and if there is (step S110 (NO)), the determination is made. finish. On the other hand, if there is no other diagnosis information (step S110 (YES)), the process proceeds to step S120.

In step S120, the opening degree of the three-way valve 50 is adjusted to 50%. That is, the opening degree of the three-way valve 50 on the radiator 30 side and the opening degree of the three-way valve 50 on the bypass flow path BL side are adjusted, and the flow rate of the cooling water flowing to the radiator 30 side and the cooling water flowing to the bypass flow path BL side are adjusted. The opening degree of the three-way valve 50 is adjusted so that the ratio with the flow rate is equal. After adjusting the opening degree of the three-way valve 50 in this way, the process proceeds to step S130.

In step S130, whether or not the measured value of the power consumption of the water pump 60 (hereinafter, also simply referred to as “measured value”) is smaller than the estimated value of the power consumption of the water pump 60 (hereinafter, also simply referred to as “estimated value”). Is determined. The estimated value of the power consumption of the water pump 60 may be estimated from, for example, the flow rate of the cooling water pumped by the water pump 60 (hereinafter, also referred to as “pump flow rate”). This cooling water flow rate is estimated by a map based on the cooling water temperature and the rotation speed of the water pump 60 (or a calculation formula showing the relationship between the cooling water temperature and the rotation speed of the water pump 60). As the cooling water temperature, it is preferable to use the value detected by the temperature sensor arranged near the water pump 60, but for example, the detected value of the temperature sensor 41 arranged at the outlet of the radiator 30 can be used. Further, the pump flow rate may be estimated by installing pressure sensors (not shown) at the inlet and outlet of the water pump 60 to measure the head of the water pump 60 and based on the measured values, or the pump flow rate may be estimated. A flow rate sensor for estimation may be installed. As a method different from the method of calculating the estimated value as described above, the estimated value of the power consumption of the water pump 60 is mapped based on the cooling water temperature and the rotation speed of the water pump 60 (or the cooling water temperature and the water pump 60). It may be calculated directly by the calculation formula) which shows the relationship of the number of rotations of.

When the measured value of the power consumption of the water pump 60 is equal to or greater than the estimated value of the power consumption of the water pump 60 (step S130 (NO)), the determination flow shown in FIG. 2 is terminated. On the other hand, when the measured value of the power consumption of the water pump 60 is smaller than the estimated value of the power consumption of the water pump 60 (step S130 (YES)), the cooling water circulation flow path is abnormal based on the map shown in FIG. 3 (A). It is determined that there is (that is, there is an abnormality in the cooling water flow path blockage or the cooling water leakage) (step S140).

Next, in step S150, the three-way valve 50 is fully opened and the entire amount of cooling water flows through the radiator flow path RL. In other words, the bypass flow path BL side of the three-way valve 50 is closed.

Next, in step S160, it is determined whether or not the measured value of the power consumption of the water pump 60 is equal to or higher than the estimated value of the power consumption of the water pump 60. When the measured value is equal to or higher than the estimated value (step S160 (YES)) when the entire amount of cooling water is flowing through the radiator flow path RL in this way, the radiator flow path RL is based on the map shown in FIG. 3 (A). It is determined that normal, that is, the radiator flow path RL is not blocked. That is, in this case, it is determined that the bypass flow path BL is abnormal. As described above, in the present embodiment, when the abnormal state (blockage of the cooling water flow path, leakage of cooling water) is resolved by closing the valve on the bypass flow path BL side of the three-way valve 50, it is determined that the bypass flow path BL is abnormal. On the other hand, when the measured value is less than the estimated value (step S160 (NO)), the process proceeds to step S170.

In step S170, the three-way valve 50 is fully closed and the entire amount of cooling water flows through the bypass flow path BL. That is, the radiator flow path RL side of the three-way valve 50 is closed.

Next, in step S180, it is determined whether or not the measured value of the power consumption of the water pump 60 is equal to or higher than the estimated value of the power consumption of the water pump 60. When the measured value is equal to or higher than the estimated value (step S180 (YES)) when the entire amount of cooling water is flowing through the bypass flow path BL in this way, the bypass flow path BL is based on the map shown in FIG. 3 (A). It is determined that normal, that is, the bypass flow path BL is not blocked. That is, in this case, it is determined that the radiator flow path RL is abnormal. As described above, in the present embodiment, when the abnormal state (blocking of the cooling water flow path, leakage of cooling water) is resolved by closing the valve on the radiator flow path RL side of the three-way valve 50, it is determined that the radiator flow path RL is abnormal. On the other hand, when the measured value is less than the estimated value (step S180 (NO)), the process proceeds to the next step S190.

In step S190, regardless of whether the cooling water is passed through the radiator flow path RL or the bypass flow path BL, the flow path is blocked, so that the flow path is blocked regardless of the opening degree of the three-way valve 50. It is determined that the stack flow path SL is blocked. As described above, in the present embodiment, the abnormal state (that is, the state in which the measured value of the pump power consumption is smaller than the estimated value) is eliminated by closing both the bypass flow path BL side and the radiator flow path RL side in the three-way valve 50. If not, it is determined that the stack flow path SL is blocked.

As described above, in the present embodiment, due to the reduction of the power consumption of the water pump 60, not only the cooling water leakage in the circulation flow path 20 (stack flow path SL, radiator flow path RL and bypass flow path BL) but also the flow flow. It can also detect road blockages. Further, as described above, by monitoring the change in power consumption when the opening degree of the three-way valve 50 is changed, the blocked portion in the circulation flow path 20 can be specified.

In steps S130, S160, and S180 described with reference to FIG. 2, when the measured value of the power consumption of the water pump 60 is smaller than the estimated value of the power consumption of the water pump 60, FIG. 3 (A) shows. Based on the map shown, it is determined that there is a flow path abnormality (that is, there is a flow path blockage or there is a cooling water leak), but the determination of the flow path abnormality state in the present embodiment is not limited to this example. That is, since the relationship between the change in pressure loss and the change in power consumption caused by the blockage of the flow path differs depending on the method of the pump used as the water pump 60, the judgment conditions different from the above-mentioned judgment of the abnormal flow path state according to this relationship. May be. As an example, when a turbo type (impeller) pump is used as the water pump 60, if the pressure loss increases due to a flow path blockage or the like, the cooling water flow rate decreases at the same rotation speed and the power consumption also decreases. The determination conditions are the same as the above-mentioned determination conditions for the abnormal flow path state (step S130, step S160, step S180 shown in FIG. 2). On the other hand, as another example, when a positive displacement pump is used as the water pump 60, even if the pressure loss increases due to the flow path blockage or the like, the cooling water flow rate is the same at the same rotation speed and the power consumption increases. , The determination condition is the opposite of the determination condition (step S130, step S160, step S180) of the flow path abnormal state described above. That is, when the measured value of the power consumption of the water pump 60 is larger than the estimated value of the power consumption of the water pump 60, it is determined that there is a flow path abnormality based on the map shown in FIG. 3 (B).

Subsequently, the evacuation running (fail safe) when the blocked portion is specified as described above will be described. FIG. 4 is a flowchart showing an example of fail-safe when the blockage of the bypass flow path BL is specified. FIG. 5 is a flowchart showing an example of fail-safe when the blockage of the radiator flow path RL is specified.

As shown in FIG. 4, when the blockage of the bypass flow path BL is specified, the warning lamp of "bypass flow path blockage" is turned on (step S210). This makes it possible to notify the user of an abnormality in the bypass flow path.

Next, in step S220, it is determined whether or not the cooling system parts have just been replaced. If it is immediately after the replacement of the cooling system parts (step S220 (YES)), the part replaced immediately before is identified as the source of the abnormality (step S230), and after the parts are replaced (step S232), the above-mentioned abnormality occurrence location is specified. The flow shifts to (step S234).

Returning to step S220, if it is not immediately after replacing the cooling system parts (step S220 (NO)), cooling control is performed when the bypass flow path is blocked (step S240). Specifically, the three-way valve 50 (FIG. 1) is fully opened to allow the entire amount of cooling water to flow to the radiator flow path RL side, the flow rate pumped by the water pump 60 is throttled, and the target value of the cooling water temperature is set higher than usual. ..

Next, in step S250, it is determined whether or not the cell voltage is lower than the lower limit threshold value, and if the cell voltage is equal to or higher than the lower limit threshold value (step S250 (NO)), until it is determined that the cell voltage is lower than the lower limit threshold value. Step S250 is repeated. When it is determined that the cell voltage is lower than the lower limit threshold value (step S250 (YES)), the output is limited (step S260).

Next, in step S270, it is determined whether or not the cell voltage is lower than the lower lower limit, and if the cell voltage is equal to or higher than the lower lower limit (step S270 (NO)), until it is determined that the cell voltage is lower than the lower lower limit. Step S270 is repeated. When it is determined that the cell voltage is lower than the lower and lower limits (step S270 (YES)), the battery is used for evacuation without using the fuel cell.

Subsequently, the evacuation running control when the blockage of the radiator flow path RL is specified will be described with reference to FIG.

When the blockage of the radiator flow path RL is specified, first, in step S310, the warning lamp for the blockage of the radiator flow path is turned on. As a result, the user can be notified of the blockage status of the radiator flow path RL.

Next, in step S320, it is determined whether or not the cooling system parts have just been replaced. If the cooling system component has just been replaced (step S320 (YES)), the component replaced immediately before is identified as the source of the abnormality (step S330), and after the component has been replaced (step S332), with reference to FIG. The process proceeds to the above-described abnormal occurrence location identification flow (step S334).

Returning to step S320, if it is not immediately after replacing the cooling system parts (step S320 (NO)), the process proceeds to step S340, and the cooling control when the radiator flow path RL is blocked is executed. The cooling control when the radiator flow path RL is closed is a control in which the three-way valve 50 is fully closed and the entire amount of cooling water flows to the bypass flow path BL side to increase the flow rate pumped by the water pump 60.

Next, in step S350, the evacuation run when the radiator flow path RL is closed is executed. As shown in FIG. 6, when an abnormality occurs, that is, when a failure occurs, the limit start temperature is set lower and the limit rate is increased than in the normal state (dotted line G1 shown in FIG. 6) (solid line G2 shown in FIG. 6). When the outside air temperature is high, the limit start temperature is set lower and the limit rate is further increased (solid line G3 shown in FIG. 6).

According to the present embodiment described above, the flow path is based on a map (see FIG. 3) showing the relationship between the estimated flow rate based on the rotation speed of the water pump 60 and the temperature of the cooling water and the power consumption of the water pump 60. An abnormal state (cooling water leakage, flow path blockage, etc.) can be determined. Then, by determining whether or not the flow path abnormality state has been resolved by closing the valve on the radiator flow path side or the bypass flow path side of the three-way valve 50, the stack flow path SL and the bypass flow path BL in the circulation flow path 20 are determined. Alternatively, it is possible to determine which flow path of the radiator flow path RL has an abnormality. As a result, it is possible to easily identify the location where the abnormality occurs in the circulation flow path 20.

The embodiments described above are for facilitating the understanding of the present invention, and are not for limiting and interpreting the present invention. Each element included in the embodiment and its arrangement, material, condition, shape, size, etc. are not limited to those exemplified, and can be changed as appropriate. In addition, the configurations shown in different embodiments can be partially replaced or combined.

1 ... Fuel cell cooling system 10 ... Fuel cell stack 20 ... Circulation flow path 21 ... Bypass pipe 30 ... Radiator 41, 42 ... Temperature sensor 50 ... Three-way valve 60 ... Water pump 70 ... Intercooler 75 ... Ion exchanger 100 ... Control unit BL ... Bypass flow path RL ... Radiator flow path SL ... Stack flow path

Claims (1)

A fuel cell system including a fuel cell, a cooling water circulation flow path for circulating cooling water for cooling the fuel cell, and a cooling water pump provided in the cooling water circulation flow path for pumping the cooling water. ,
The cooling water circulation flow path is
A stack flow path for flowing cooling water through the fuel cell,
A radiator flow path that has a radiator that releases the heat of the cooling water to the outside and is connected to both ends of the stack flow path so that the cooling water circulates between the radiator and the fuel cell.
It is provided with a bypass flow path for branching from one end of both ends of the stack flow path, merging with the other end, bypassing the radiator flow path, and allowing cooling water to flow.
A three-way valve provided at one end of both ends of the stack flow path and adjusting the flow rate ratio of the cooling water flowing into the radiator flow path and the bypass flow path.
A control unit that stores a map for determining a flow path abnormal state based on the estimated flow rate estimated based on the rotation speed of the cooling water pump and the temperature of the cooling water and the power consumption of the cooling water pump. And have
In a state where the cooling water is flowing through both the radiator flow path and the bypass flow path, when the flow path abnormality state is determined by the control unit,
When the flow path abnormality state is resolved by closing the valve on the bypass flow path side of the three-way valve, it is determined that the bypass flow path is abnormal.
When the flow path abnormality state is resolved by closing the valve on the radiator flow path side of the three-way valve, it is determined that the radiator flow path is abnormal.
A fuel cell system characterized in that when the flow path abnormality state is not resolved by the opening degree control of the three-way valve, it is determined that the stack flow path is abnormal.

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