JP2018181654A - Fuel cell cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell cooling system which allows for easy identification of an abnormality occurrence place, upon occurrence of an abnormality in a cooling water circulation passage.SOLUTION: When an ECU100 determines passage abnormality state in a state where cooling water is fed to both radiator passage RL and bypass passage BL, a fuel cell cooling system 1 determines that the bypass passage BL is abnormal if the passage abnormality state is resolved by closing a three-way valve 50 on the bypass passage side, determines that the radiator passage RL is abnormal if the passage abnormality state is resolved by closing the three-way valve 50 on the radiator passage side, and determines that the stack passage SL is abnormal if the passage abnormality state is not resolved by opening control of the three-way valve 50.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel cell cooling system.

  Fuel cells are generally used as a fuel cell stack in which a plurality of fuel cells (hereinafter also referred to as cells) are stacked. Each cell is configured by sandwiching an MEA composed of an electrolyte membrane and an anode (fuel electrode) and a cathode (air electrode) respectively bonded to both surfaces thereof with a pair of separators.

  Fuel cells have a suitable operating temperature range which depends on the type of electrolyte membrane. Even if the internal temperature of the fuel cell is higher or lower than the operating temperature range, sufficient power generation performance can not be obtained. For this reason, the separator of each cell is provided with a gas flow path for supplying fuel gas to the anode and a gas flow path for supplying oxidizing gas to the cathode, and a cooling water flow path for flowing cooling water. The fuel cell is cooled by the cooling water to suppress the temperature rise due to the reaction heat, and the temperature is adjusted to an appropriate operating temperature.

  Cooling water for cooling a fuel cell is usually reused repeatedly. For this reason, the fuel cell system is provided with a cooling water circulation channel 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 is a stack flow path for flowing the cooling water to the fuel cell, a radiator flow path connected to the stack flow path and having a radiator, and a bypass flow bypassing the radiator. A three-way valve is provided to switch the flow rate ratio of the cooling water flowing in the radiator flow path or the bypass flow path.

JP, 2005-285489, A

  By the way, when abnormality, such as a cooling water leak etc. generate | occur | produces in the said cooling water circulation flow path, it is necessary to detect the generation | occurrence | production promptly. Conventionally, although a technique for detecting such a coolant leak has been proposed, it is not possible to determine which of the stack coolant channel, the radiator channel, and the bypass channel has an abnormality in the coolant circulation channel, It was difficult to identify the place where the abnormality occurred.

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

  A fuel cell cooling system according to the present invention comprises a fuel cell, a cooling water circulation flow path through which cooling water for cooling the fuel cell is circulated, and a cooling water pump provided in the cooling water circulation flow path to circulate the cooling water. In the fuel cell system, the cooling water circulation flow path has a stack flow path for flowing the cooling water to the fuel cell and a radiator for discharging the heat of the cooling water to the outside, and the cooling is performed between the radiator and the fuel cell A radiator flow path connected to both ends of the stack flow path so that water is circulated, and one end of the stack flow path branches from one end and joins to the other end, bypassing the radiator flow path and cooling water A three-way valve provided with a bypass channel for flowing, provided at one end of both ends of the stack channel, and adjusting a flow ratio of cooling water flowing into the radiator channel and the bypass channel; Speed and cooling A controller for storing a map for determining an abnormal flow condition based on the estimated flow rate estimated based on the temperature of the pump and the power consumption of the pump of the cooling water; In the state where the cooling water is flowing to both sides of the passage, when it is determined by the flow passage abnormal state and the control unit, when the flow passage abnormal state is eliminated by closing the bypass flow passage side of the three-way valve It is determined that the flow path is abnormal. When the flow path abnormal state is eliminated by closing the radiator flow path side of the three-way valve, it is determined that the radiator flow path is abnormal, and the flow path abnormal state is eliminated by the opening control of the three-way valve. If not, it is determined that the stack flow path is abnormal.

  According to this configuration, the flow path abnormal state is determined based on the map based on the relationship between the estimated flow rate and the power consumption, and the flow path abnormal state is eliminated by closing the radiator flow path side or the bypass flow path side in the three-way valve. It is possible to determine which flow path of the stack flow path, the bypass flow path, or the radiator flow path in the cooling water circulation flow path has an abnormality by determining whether or not it has occurred. Thus, it is possible to easily identify the abnormality occurrence point in the cooling water circulation channel.

  ADVANTAGE OF THE INVENTION According to this invention, when abnormality generate | occur | produces in a cooling water circulation flow path, the fuel cell cooling system which can identify the abnormality generation part easily can be provided.

It is a schematic block diagram of the fuel cell cooling system in this embodiment. It is a flowchart which shows an example of an abnormality generation place 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 flow chart which shows an example of fail-safe processing at the time of bypass channel blockade. It is a flow chart which shows an example of fail-safe processing at the time of radiator channel blockade. It is a graph for demonstrating a restriction | limiting start temperature and a restriction | limiting 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 attached drawings. The following description of the preferred embodiments is merely an example, and is not intended to limit the present invention, its applications, or its applications.

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

  The fuel cell stack 10 has a stack structure in which a plurality of fuel cells that generate electric power using an electrochemical reaction of hydrogen and oxygen are stacked. Each fuel cell comprises an electrolyte membrane, an anode and a cathode. The anode and the cathode are, for example, an electrode catalyst layer supporting a catalyst such as platinum or platinum alloy. The electrolyte membrane constitutes a membrane electrode assembly (MEA) with the anode and the cathode joined on both sides thereof. The fuel cell has a configuration in which the MEA is sandwiched by a pair of separators.

  The circulation flow passage 20 is a flow passage 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 of the lower part of the fuel cell stack 10 in the drawing and the cooling water inlet of the upper part in the drawing. As cooling water, in order to prevent freezing at low temperature, for example, a mixed solution of ethylene glycol and water can be used.

  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 passage SL is a flow passage connected to the inlet side and the outlet side of the fuel cell stack 10 in order to flow the cooling water to 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 for discharging the heat of the cooling water to the outside, and is a flow path 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 It is. The bypass flow path BL is a flow path for branching from one end of the both ends of the stack flow path SL and joining the other end and bypassing the radiator flow path RL to circulate the cooling water. Note that in FIG. 1, the areas indicated by the stack flow path SL, the bypass flow path BL, and the radiator flow path RL are illustrated schematically, and are not limited to the areas illustrated in FIG. 1.

  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. Note that, as shown in FIG. 1, in addition to the configuration in which the radiator 30 is provided in the radiator flow path RL, a configuration may be employed in which a sub radiator 35 that assists the heat exchange function of the radiator 30 is provided.

  One end (i.e., the upstream side of the radiator flow passage RL) of the both ends of the stack flow passage SL (i.e., the connection portion between the stack flow passage SL and the radiator flow passage RL) bypasses the radiator 30 and circulates the cooling water. It is a flow path which branches from the radiator flow path RL and merges with 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 a branch position upstream of the radiator 30 on the cooling water flow, and is connected to the radiator flow path RL at a junction position on the cooling water downstream of the radiator 30 Flow path. Thus, by providing the bypass pipe 21 and controlling the opening degree of the three-way valve 50 described later, it is possible to bypass the radiator flow path RL and circulate the cooling water in the stack flow path SL and the bypass pipe 21. The bypass pipe 21 is provided with a cooling water passage connected in parallel to the bypass pipe 21. In the cooling water passage, an ion exchanger 75 serving as an ion adsorbing means is disposed. For example, an ion exchange resin is filled in the ion exchanger 75. Since the cooling water is in contact with the fuel cell in the fuel cell stack 10, the ion exchanger 75 adsorbs and removes ions from the cooling water to suppress an increase in the conductivity of the cooling water. In the present specification, a flow path including a pipe passing through the bypass pipe 21 and the ion exchanger 75 will be described 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 passage SL) branched to the bypass flow passage BL on the upstream side of the radiator flow passage RL. In other words, the three-way valve 50 is provided on one side (upstream of the radiator flow passage RL) of the connection positions of the radiator flow passage RL and the stack flow passage SL. The three-way valve 50 is a valve device that adjusts the flow ratio of the coolant flowing into the radiator channel RL and the coolant flowing into the bypass channel BL. The three-way valve 50 has an inlet for the cooling water flowing in from the upstream side, a first outlet for letting the cooling water flow out to the radiator 30 side, and a second outlet for letting the cooling water flow out to the bypass pipe 21 side. And the opening degree of the first outlet and the second outlet can be adjusted.

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

  In the circulation flow passage 20, a cooling water passage for bypassing the fuel cell stack 10 is provided, and an intercooler 70 is disposed in the 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 is configured to adjust the temperature of the air supplied to the fuel cell stack 10 to a suitable temperature. .

  In the circulation flow path 20, temperature sensors 41 and 42, which are temperature detection means for detecting the temperature of the cooling water, are disposed. The temperature sensor 41 (radiator outlet temperature sensor) is disposed downstream of the radiator 30 in the coolant flow, and the temperature sensor 42 (stack outlet temperature sensor) is disposed downstream of the fuel cell stack 10 in the coolant flow. The temperature information of the cooling water detected by each of 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 configured by a computer system (not shown). The computer system includes a CPU, a ROM, a RAM, an HDD, an input / output interface and the like, and the CPU reads and executes various control programs recorded in the ROM to realize various control operations. It has become. The ECU 100 inputs, for example, information on the calorific value or power generation of the fuel cell output from the fuel cell stack 10, and temperature information output from the temperature sensors 41 and 42, and the three-way valve 50 or water based on these input information. The pump 60 is driven and controlled. The ECU 100 also monitors, for example, the power consumption of the water pump 60 and stores it. 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 to flow the cooling water to the radiator 30 for cooling. On the other hand, when it is lower than the predetermined value, the three-way valve 50 is controlled so that the cooling water flows in the bypass flow path BL including the ion exchanger 75. Further, for example, the ECU 100 detects the conductivity of the circulation flow passage 20 by a predetermined conductivity detection means (not shown), and when the conductivity is lower than a predetermined value, the bypass flow passage BL including the ion exchanger 75 Control the three-way valve 50 so as to reduce the conductivity. The adjustment of the opening degree of the three-way valve 50 in the present embodiment will be described later with reference to FIG.

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

  In the ECU 100, as shown in FIG. 3A, the estimated flow rate of the 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 relation of power consumption (or a calculation formula indicating the relation 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 number of revolutions (rpm) of the water pump 60. Based on the map in FIG. 3A (the horizontal axis is the estimated flow rate (rpm) and the vertical axis is the power consumption (w)), the estimated flow rate-power consumption line in the normal state shown in FIG. 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. It can be determined that there is no flow path obstruction, no flow path leakage, and if it is less than the estimation line R1 shown in FIG. 3A, it can be determined as abnormal (flow path obstruction, cooling water leakage) .

  Further, as shown in FIG. 3B, in the ECU 100, 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. A map based on (1) (or a formula that shows 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) indicates the estimated flow rate (rpm), and the vertical axis indicates the power consumption (w). Based on the map shown in FIG. 3B, in the case of the region above the estimated flow rate-power consumption line (hereinafter also referred to as estimated line R2) in the normal state shown in FIG. 3B, in other words, predetermined If the measured value of the power consumption of the water pump 60 at the time of flow rate is equal to or greater than the estimated line R2 shown in FIG. 3B, it can be determined as abnormal (flow path blockage, cooling water leakage). When it is less than the estimated line R2 shown in (B), it can be determined as normal (no flow path obstruction, no flow path leakage).

  In the present embodiment, the rotational speed target value of the water pump 60 (hereinafter, also referred to as a “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 pump rotational speed target value is calculated, and a control signal is output to the pump based on the pump rotational speed target value (signal A1 shown in FIG. 7). The power consumption and rotational speed of the pump are input from the pump to the ECU (signal A2 shown in FIG. 7). The input power consumption and rotational speed are stored in the ECU, and a channel 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 channel blockage determination, converts the target opening degree into a drive signal, and controls the opening degree of the three-way valve 50. Further, the ECU calculates a pump rotational speed target value based on the channel blockage determination, and outputs the target value to the pump.

  Subsequently, an abnormality occurrence point specifying flow executed in the above-described fuel cell cooling system will be described. FIG. 2 is a flowchart showing an example of an abnormality occurrence point identification flow. The determination process for identifying the abnormality occurrence point, which will be described below, is executed, for example, at the time of startup, at the time of parts replacement, or at any time during operation.

  First, in step S110, the presence or absence of other diagnosis information (for example, sensor open circuit short circuit including whether the sensor is operating normally or not) is determined, and if it is present (step S110 (NO)), the determination finish. On the other hand, when 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 to flow the cooling water flowed to the radiator 30 side and the cooling water flowed to the bypass flow path BL The opening degree of the three-way valve 50 is adjusted so that the ratio to the flow rate becomes equal. After adjusting the opening degree of the three-way valve 50 as described above, the process proceeds to step S130.

  In step S130, whether or not the measured value of power consumption of water pump 60 (hereinafter, also simply referred to as "measured value") is smaller than the estimated value of power consumption of 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, for example, from the flow rate of cooling water pumped by the water pump 60 (hereinafter also referred to as “pump flow rate”). The 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 a detected value by a temperature sensor disposed in the vicinity of the water pump 60. For example, a detected value of a temperature sensor 41 or the like disposed at the outlet of the radiator 30 can be used. Also, the pump flow rate may be estimated based on the measurement value by installing a pressure sensor (not shown) at the inlet and outlet of the water pump 60 and measuring the head of the water pump 60, or You may install the flow sensor for estimating. As another method of calculating the estimated value as described above, the estimated value of the power consumption of the water pump 60 may be a map based on the cooling water temperature and the rotational speed of the water pump 60 (or the cooling water temperature and the water pump 60 It is good also as calculating directly by the formula which shows the relation of the number of rotations of.

  If the measured value of the power consumption of the water pump 60 is equal to or more than the estimated value of the power consumption of the water pump 60 (step S130 (NO)), the determination flow shown in FIG. 2 is ended. 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 channel is abnormal based on the map shown in FIG. It is determined that there is (that is, there is an abnormality in the cooling water flow passage blockage or cooling water leakage) (step S140).

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

  Next, in step S160, it is determined whether the measured value of the power consumption of the water pump 60 is equal to or more than the estimated value of the power consumption of the water pump 60. As described above, when the total amount of cooling water is flowing through the radiator flow path RL, when the measured value is equal to or more than the estimated value (step S160 (YES)), the radiator flow path RL is based on the map shown in FIG. It is determined that the radiator flow path RL is not closed. That is, in this case, it is determined that the bypass channel BL is abnormal. As described above, in this embodiment, when the abnormal state (blockage of the cooling water flow path, cooling water leakage) is eliminated by closing 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 is allowed to flow through the bypass passage 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 the measured value of the power consumption of the water pump 60 is equal to or more than the estimated value of the power consumption of the water pump 60. As described above, when the total amount of cooling water is flowing through the bypass flow path BL, when the measured value is equal to or larger than the estimated value (step S180 (YES)), the bypass flow path BL is based on the map shown in FIG. It is determined that normal, that is, the bypass flow passage 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 (blockage of the cooling water flow path, cooling water leakage) is eliminated by closing 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, even if the coolant is supplied to the radiator flow path RL or the coolant is supplied to the bypass flow path BL, the flow path is blocked regardless of the opening degree of the three-way valve 50 because the flow path is blocked. 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 any of 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, not only cooling water leakage in the circulation flow passage 20 (the stack flow passage SL, the radiator flow passage RL, and the bypass flow passage BL) but also the flow is caused by the reduction of the power consumption of the water pump 60. Road blockage can also be detected. Further, as described above, by monitoring the change in power consumption when the opening degree of the three-way valve 50 is changed, it is possible to identify the blockage point in the circulation flow path 20.

  In step S130, step S160, and step S180 described with reference to FIG. 2, if 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. Although it is determined that there is a flow path abnormality (that is, there is a flow path blockage or a cooling water leak) based on the map shown, the determination of the flow path abnormal state in the present embodiment is not limited to this example. That is, since the relationship between the change in pressure loss caused by channel blockage and the like and the change in power consumption varies depending on the type of pump used as water pump 60, the determination condition is different from the determination of the channel abnormal state described above according to this relationship. As well. As an example, when a turbo type (impeller) pump is used as the water pump 60, if the pressure loss increases due to passage blockage etc., 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 determination conditions of the flow path abnormal state described above (step S130, step S160, and 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, the cooling water flow rate is the same at equal rotation speed even if the pressure loss rises due to passage blockage etc., and the power consumption increases. The determination condition is the reverse of the determination condition of the flow passage abnormal state (step S130, step S160, step S180) 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 the flow passage is abnormal based on the map shown in FIG. 3 (B).

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

  As shown in FIG. 4, when the blockage of the bypass flow passage BL is identified, the warning lamp of the “bypass flow passage blockage” is turned on (step S210). Thereby, the user can be notified of the abnormality of the bypass flow channel.

  Next, in step S220, it is determined whether the cooling system component has just been replaced. If the cooling system part has just been replaced (step S220 (YES)), the part replaced immediately before is identified as an abnormality generation source (step S230), and after replacing the part (step S232) It shifts to a flow (step S234).

  Returning to step S220, if it is not immediately after the replacement of the cooling system components (step S220 (NO)), the cooling control at the time of blocking the bypass flow passage is performed (step S240). Specifically, the three-way valve 50 (FIG. 1) is fully opened to flow the entire amount of cooling water to the radiator flow path RL side, squeeze the flow rate pumped by the water pump 60, and make the target value of the cooling water temperature higher than usual. .

  Next, in step S250, it is determined whether the cell voltage is lower than the lower threshold, and if the cell voltage is higher than the lower threshold (step S250 (NO)), it is determined that the cell voltage is lower than the lower threshold Step S250 is repeated. When it is determined that the cell voltage is lower than the lower threshold (step S250 (YES)), output restriction is performed (step S260).

  Next, in step S270, it is determined whether the cell voltage is lower than the lower limit, and if the cell voltage is higher than the lower limit (step S270 (NO)), it is determined that the cell voltage is lower than the lower limit Step S270 is repeated. If it is determined that the cell voltage is lower than the lower limit (step S 270 (YES)), the fuel cell is not used and evacuation travel is performed with the battery.

  Subsequently, with reference to FIG. 5, evacuation traveling control when blockage of the radiator flow path RL is identified will be described.

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

  Next, in step S320, it is determined whether the cooling system component has just been replaced. If the cooling system part has just been replaced (step S320 (YES)), the part replaced immediately before is identified as an abnormality source (step S330), and after replacing the part (step S332), referring to FIG. The flow proceeds to the described abnormality occurrence point identification flow (step S334).

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

  Next, in step S350, evacuation travel is performed when the radiator flow passage RL is closed. As shown in FIG. 6, the limit start temperature is set lower and the limit rate is increased (solid line G2 shown in FIG. 6) than when normal (dotted line G1 shown in FIG. 6). When the outside air temperature is high, the restriction start temperature is set lower and the restriction rate is further increased (solid line G3 shown in FIG. 6).

  According to the present embodiment described above, the flow path based on the 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 leak, channel blockage, etc.) can be determined. Then, by determining whether or not the flow path abnormal state has been eliminated by closing the radiator flow path side or the bypass flow path side in the three-way valve 50, the stack flow path SL, the bypass flow path BL in the circulation flow path 20, Alternatively, it can be determined in which flow path of the radiator flow path RL an abnormality has occurred. In this way, it is possible to easily identify the abnormality occurrence point in the circulation flow passage 20.

  The embodiments described above are for the purpose of facilitating the understanding of the present invention, and are not for the purpose of limiting the present invention. The elements included in the embodiment and the arrangement, the material, the conditions, the shape, the size, and the like of the elements are not limited to those illustrated, and can be changed as appropriate. In addition, configurations shown in different embodiments can be partially substituted or combined with each other.

DESCRIPTION OF SYMBOLS 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 part BL ... bypass flow path RL ... radiator flow path SL ... stack flow path

Claims (1)

A fuel cell system comprising: a fuel cell; a cooling water circulation flow path through which cooling water for cooling the fuel cell is circulated; and a cooling water pump provided in the cooling water circulation flow path and pumping the cooling water ,
The cooling water circulation channel is
A stack flow path for flowing cooling water to the fuel cell;
A radiator flow path connected to both ends of the stack flow path such that the cooling water is circulated between the radiator and the fuel cell; and a radiator for discharging the heat of the cooling water to the outside;
And a bypass flow path for branching the coolant from the one end of the stack flow path, bypassing from the one end of the stack flow path and joining the other end.
A three-way valve provided at one end of the both ends of the stack flow path, for 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 rotational speed of the cooling water pump and the temperature of the cooling water, and the power consumption of the cooling water pump And
In a state where the cooling water is flowing to both the radiator flow path and the bypass flow path, when the flow path abnormality state and the control unit make a determination,
When the flow path abnormal state is eliminated by closing the bypass flow path side of the three-way valve, it is determined that the bypass flow path is abnormal;
When the channel abnormal state is eliminated by closing the radiator channel side of the three-way valve, it is determined that the radiator channel is abnormal.
A fuel cell system characterized in that the stack flow path is determined to be abnormal when the flow path abnormal state is not resolved by the opening control of the three-way valve.

Images