JP2011018461A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system by which driving performance of a vehicle mounted with a fuel cell is improved.SOLUTION: The fuel cell system includes a gradient sensor 60 or a navigation system 74 and a fuel cell ECU 24. The fuel cell ECU 24 includes: a determination means which determines as an intermittent operation power generation shutdown condition completion to perform power generation operation shutdown or the like of the fuel cell stack 12 when a certain condition is satisfied; an execution means; and a prohibition means. The execution means executes the intermittent operation power generation shutdown when the vehicle is not at a stop or not running at an uphill and is determined to satisfy the intermittent operation power generation shutdown condition completion. The prohibition means prohibits the intermittent operation power generation shutdown when either one or both of the cases are satisfied that the vehicle is at a stop or running at an uphill and that the determination means determines that the intermittent operation power generation shutdown condition completion is not completed.

Description

  The present invention relates to a fuel cell system that is mounted on a vehicle and includes a fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidizing gas, and a control unit that controls the power generation operation of the fuel cell.

  The fuel cell stack is, for example, a fuel cell in which a membrane-electrode assembly (MEA) having an anode side electrode and a cathode side electrode present on both sides of an electrolyte membrane and a separator are used as one set of fuel cells, and a plurality of these are stacked. It is composed of a laminate. That is, each fuel cell is configured by arranging an anode side electrode on one side of an electrolyte membrane made of a polymer ion exchange membrane, a cathode side electrode on the other side, and further providing separators on both sides. is doing. A plurality of such fuel cell units are stacked and sandwiched between current collector plates, insulating plates, end plates, and the like to constitute a fuel cell stack that generates a high voltage.

  In such a fuel cell, a fuel gas, for example, a gas containing hydrogen is supplied to the anode side electrode, and an oxidizing gas, for example, air is supplied to the cathode side electrode. As a result, the fuel gas and the oxidizing gas are subjected to an electrochemical reaction to generate an electromotive force, and water is generated at the cathode side electrode.

  Such a fuel cell is also considered to be a fuel cell vehicle that is mounted on a vehicle and uses the fuel cell as a power source of a travel motor that is a drive source of the vehicle. Further, in such a fuel cell system including a fuel cell for mounting on a vehicle, when a certain condition regarding the required power generation amount of the fuel cell and the charge amount of a power storage unit such as a secondary battery is satisfied, the fuel cell power generation operation It is conceivable to perform an operation called intermittent operation that restarts the power generation operation of the fuel cell when a certain condition is not satisfied when electric power corresponding to the required power generation amount is supplied to the load by the power storage unit. ing. In this case, when a certain condition is satisfied, the fuel cell power generation is stopped. For this reason, it can prevent effectively that a fuel cell generates electric power excessively, and it is easy to aim at energy saving.

  Japanese Patent Application Laid-Open No. 2004-228561 detects the accelerator depression amount and gradient, predicts that the load on the fuel cell increases from these detection values, and controls the pressure on the output side of the pressure regulating valve that supplies the fuel gas. A fuel cell system that suppresses leaching of generated water into the fuel chamber by increasing the fuel gas pressure before the generated water starts leaching to the anode due to an increase in load and pushing the generated water into the electrolyte membrane. Are listed.

  Further, in Patent Document 2, the control unit of the fuel cell system limits the output voltage of the fuel cell once with the oxidation-reduction potential even when the system required power gradually increases, which corresponds to the limited voltage. A fuel cell system for controlling power to be supplemented by a battery is described. Further, in the fuel cell system described in Patent Document 2, a continuation threshold value indicating the maximum duration time for limiting the amount of change in generated power is set, and the control means sets the amount of change in the power generated by the fuel cell within the range of the continuation threshold value. The control means detects the road condition on which the moving body travels, and changes the continuation threshold according to the detection result.

  Patent Document 3 discloses a fuel cell, a secondary battery that is a power storage unit that is charged by the fuel cell, and a fuel cell that is intermittently mounted according to the amount of charge of the secondary battery. In a fuel cell system comprising a control device that is a power generation control means for performing control for driving, when the control device determines that traveling at a high load is continued, power is generated regardless of the charge amount of the secondary battery. The control of the fuel cell is described as follows.

JP 2008-251489 A JP 2007-5038 A JP 2005-44531 A

  As described above, in a fuel cell vehicle equipped with a fuel cell, when adopting a configuration in which the fuel cell is intermittently operated, power generation is stopped when the vehicle is stopped on an uphill or traveling on an uphill on the control unit. Then, there is a possibility that sufficient traveling performance on the uphill road cannot be secured effectively. For example, when the fuel cell vehicle is stopped on an uphill road, the required power generation amount obtained from the detected value of the accelerator pedal stroke may be less than the threshold value corresponding to intermittent power generation stoppage, and the power generation stop state is entered. It is possible to do. In this case, when the driver tries to restart the vehicle by depressing the accelerator pedal, there is a delay until the auxiliary machine such as an air compressor that supplies oxidizing gas to the fuel cell is normally driven, There may be a delay in the fuel supply from the gas supply source to the fuel cell, and there may be a delay in securing the required power of the fuel cell.

  For example, FIG. 4 shows an accelerator pedal stroke, a power generation operation state, an air flow when a vehicle starts moving from a stop on an uphill road in a fuel cell system that has been conventionally considered. It is a figure which shows one example of the time passage of the rotation speed of a compressor, and the generated electric power of a fuel cell. As shown in FIG. 4, when power generation is stopped during intermittent operation of the fuel cell, the accelerator pedal stroke “accelerator pedal stroke” changes from zero to x% at time t1. As a result, even if the command value for the rotational speed of the air compressor suddenly rises, the actual rotational speed only increases gradually. Although illustration is omitted, there is a possibility that a fuel delay from the fuel gas supply source for supplying the fuel gas to the fuel cell to the fuel cell may also occur. For this reason, the power generated by the fuel cell only gradually increases to a desired value, and it cannot be said that there is no possibility that drivability deteriorates due to insufficient torque of the traveling motor at the time of starting. For example, it may not be possible to effectively prevent the vehicle from sliding down even if it is going to start on an uphill road. For this reason, there is a possibility that sufficient traveling performance on the uphill road cannot be effectively secured. Thus, there is room for improvement in terms of improving the running performance of a vehicle equipped with a fuel cell.

  In addition, if the air compressor continues to rotate when generating power with the minimum power generation amount, the amount of moisture taken out from the fuel cell increases, and the electrolyte membrane constituting the fuel cell is excessively dried, resulting in the fuel cell. May decrease the output of. From this aspect, there is room for improvement in terms of improving the running performance of a vehicle equipped with a fuel cell.

  On the other hand, in the case of the fuel cell system described in Patent Document 2, as described above, a continuation threshold value representing the maximum continuation time for limiting the amount of change in generated power is set, and the control means is within the continuation threshold value range. Then, the control unit continues to limit the amount of change in the generated power by the fuel cell, and the control means detects the road state on which the mobile body travels and changes the continuation threshold according to the detection result. However, in this case, it cannot be said that there is no possibility that power generation is stopped even when a vehicle equipped with a fuel cell is located on an uphill road. For this reason, there is room for improvement in terms of improving the running performance of a vehicle equipped with a fuel cell.

  Further, in the fuel cell system described in Patent Document 3, when it is determined that traveling at a high load is continued, the fuel cell is controlled to generate power. It is said that it will be performed based on the accelerator pedal operation amount detected by the device and the vehicle speed detected by the vehicle speed detector, so there is no possibility that the determination will be delayed when the vehicle restarts while stopping on the uphill road I can't say that. In addition, it cannot be determined before the vehicle enters the uphill road. For this reason, there is still room for improvement in terms of ensuring sufficient running performance on the uphill road. Further, the fuel cell system described in Patent Document 1 increases the fuel gas pressure supplied to the fuel gas chamber when it is predicted by the gradient detected by the gradient sensor that the load required for the fuel cell will increase. Has been. However, this is intended to prevent the water in the fuel chamber from stopping due to an increase in load, improving the driving performance of vehicles equipped with fuel cells, such as effectively ensuring sufficient driving performance on uphill roads. It is not a thing to consider.

  An object of the present invention is to improve the running performance of a vehicle equipped with a fuel cell in a fuel cell system.

  A fuel cell system according to the present invention includes a fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidizing gas, and a control unit that controls a power generation operation of the fuel cell, and is used by being mounted on a vehicle. A vehicle state detecting means for detecting whether the vehicle is stopped or traveling on an uphill road, a charge amount detecting means for detecting a charge amount of a power storage unit, including a gradient sensor or a navigation system; The control unit includes an acquisition unit that acquires the required power generation amount of the fuel cell, and when the required power generation amount of the fuel cell is equal to or less than the threshold power generation amount and the charge amount of the power storage unit is equal to or greater than the threshold charge amount, Determination means for determining that an intermittent operation power generation stop condition is satisfied, in which the power generation operation of the fuel cell is stopped and the power corresponding to the required power generation amount is supplied to the load by the power storage unit, and the vehicle is stopped or traveling on the uphill road If the determination means determines that the intermittent operation power generation stop condition is satisfied, the execution means for executing the intermittent operation power generation stop and the vehicle is stopped or traveling on the uphill road, and the determination means intermittently A fuel cell system comprising: prohibiting means for prohibiting intermittent operation power generation stop when one or both of determination that the operation power generation stop condition is not satisfied is satisfied.

  According to the fuel cell system of the present invention, when the required power generation amount of the fuel cell is equal to or less than the threshold power generation amount and the charge amount of the power storage unit is equal to or greater than the threshold charge amount, the power generation operation of the fuel cell is stopped. In the configuration that performs intermittent operation power generation stop by supplying power corresponding to the required power generation amount to the load by the power storage unit, when the vehicle is stopped or traveling on the uphill road, intermittent operation power generation stop is prohibited, There is no shortage of the amount of power generated when the vehicle starts on an uphill road or travels on an uphill road, and the driving force of the vehicle does not become insufficient. In addition, whether the vehicle is stopped or traveling on the uphill road is detected by a gradient sensor or a navigation system, etc., so that the vehicle is stopped or running on the uphill road based on the operation amount of the accelerator pedal and the vehicle speed. Unlike the case of detecting whether or not there is, it is possible to reduce the occurrence of delay in detection, and to more effectively secure the driving force of the vehicle in accordance with the driver's intention to accelerate. For this reason, the running performance of a vehicle equipped with a fuel cell can be improved.

  In the fuel cell system according to the present invention, preferably, the fuel cell system includes an oxidant gas passage for supplying the oxidant gas to the fuel cell and discharging the oxidant gas after the reaction from the fuel cell, and the control unit constitutes the fuel cell. Gas pressure increasing means for increasing the gas pressure in the oxidizing gas flow path when it is determined that the electrolyte membrane is dryer than the predetermined standard.

  According to the above configuration, when the intermittent operation power generation stop is prohibited and the required power generation amount is low, the oxidizing gas supply unit such as an air compressor that supplies the oxidizing gas to the fuel cell is driven, and the fuel cell tends to dry However, since the gas pressure in the oxidizing gas channel increases, it is possible to suppress the removal of water in the fuel cell by driving the oxidizing gas supply unit. For this reason, the fall of the electric power generation amount by the excessive drying of a fuel cell can be prevented.

  Further, in the fuel cell system according to the present invention, preferably, the fuel cell system includes an opening degree adjustment valve capable of adjusting an opening degree of the flow path on the gas downstream side of the fuel cell of the oxidizing gas flow path, When it is determined that the electrolyte membrane constituting the battery is dryer than the predetermined standard, the opening adjustment valve is controlled to reduce the opening of the flow path.

  The fuel cell system according to the present invention includes a fuel cell that generates power by an electrochemical reaction between a fuel gas and an oxidizing gas, and a control unit that controls the power generation operation of the fuel cell, and is used by being mounted on a vehicle. A fuel cell system comprising an oxidant gas flow path for supplying an oxidant gas to the fuel cell and discharging the oxidized gas after reaction from the fuel cell, wherein the control unit is configured such that the electrolyte membrane constituting the fuel cell is less than a predetermined standard. A fuel cell system comprising gas pressure increasing means for increasing the gas pressure in the oxidizing gas flow path when it is determined that the gas is dry.

  According to the fuel cell system of the present invention, even when the inside of the fuel cell tends to dry, the gas pressure in the oxidant gas passage increases, so that the water in the fuel cell is driven by driving the oxidant gas supply unit. Take away can be suppressed. For this reason, the fall of the electric power generation amount by drying of a fuel cell can be prevented. For this reason, the running performance of a vehicle equipped with a fuel cell can be improved. For example, even if the fuel cell is stopped from generating power and the oxidizing gas supply unit such as an air compressor that supplies oxidizing gas to the fuel cell is driven in a state where the required power generation amount is low, the fuel cell tends to dry. Since the gas pressure in the gas flow path increases, it is possible to suppress the removal of water in the fuel cell by driving the oxidizing gas supply unit. For this reason, the fall of the electric power generation amount by the excessive drying of a fuel cell can be prevented. Patent Document 1 includes a configuration for increasing the fuel gas pressure supplied to the fuel gas chamber when the load required for the fuel cell is predicted to increase by the gradient detected by the gradient sensor. The purpose of this configuration is to suppress water from stopping in the fuel gas chamber, and the purpose and means thereof are different from those of the configuration according to the present invention.

  Further, in the fuel cell system according to the present invention, preferably, the fuel cell system includes an opening degree adjustment valve capable of adjusting an opening degree of the flow path on the gas downstream side of the fuel cell of the oxidizing gas flow path, When it is determined that the electrolyte membrane constituting the battery is dryer than the predetermined standard, the opening adjustment valve is controlled to reduce the opening of the flow path.

  The fuel cell system according to the present invention can improve the running performance of a vehicle equipped with a fuel cell.

It is a figure which shows the basic composition of the fuel cell system of embodiment of this invention. It is a figure which shows the structure of the control part of FIG. 1 in detail. 2 is a flowchart showing a method for controlling the power generation operation of the fuel cell in the fuel cell system of FIG. 1. In the fuel cell system that has been considered in the past, when the fuel cell is intermittently operated, the accelerator pedal stroke, the power generation operation state, the rotation speed of the air compressor, and the fuel when the vehicle starts from a stop on an uphill road It is a figure which shows one example of the time passage of the generated electric power of a battery.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. 1 to 8 show an embodiment of the present invention.

[Configuration of fuel cell system]
FIG. 1 is a schematic configuration diagram of the present embodiment. The fuel cell system 10 is used by being mounted on a fuel cell vehicle, and has a fuel cell stack 12. The fuel cell stack 12 is a fuel cell stack in which a plurality of fuel cells are stacked, and a current collecting plate and an end plate are provided at both ends in the stacking direction of the fuel cell stack. For example, the fuel cell stack, current collector plate, and end plate are fastened with tie rods, nuts, and the like. An insulating plate can also be provided between the current collector plate and the end plate.

  Although a detailed view of each fuel cell is omitted, it is assumed that, for example, a membrane assembly in which an electrolyte membrane is sandwiched between an anode side electrode and a cathode side electrode and separators on both sides thereof are provided. Further, hydrogen gas that is a fuel gas can be supplied to the anode side electrode, and air that is an oxidizing gas can be supplied to the cathode side electrode. Then, hydrogen ions generated at the anode side electrode are moved to the cathode side electrode through the electrolyte membrane, and water is generated by causing an electrochemical reaction with oxygen at the cathode side electrode. An electromotive force is generated by moving electrons from the anode side electrode to the cathode side electrode through an external circuit.

  In order to supply air, which is an oxidizing gas, to the fuel cell stack 12, an oxidizing gas supply channel 14 is provided. An air compressor 16 that is an oxidizing gas supply source is provided upstream of the gas in the oxidizing gas supply channel 14, and the air pressurized by the air compressor 16 is humidified by the humidifier 20. The air compressor 16 is driven by a motor (not shown). The humidified air is supplied to the oxidizing gas internal flow path on the cathode side electrode side of the fuel cell stack 12.

  Air off-gas, which is a reacted oxidizing gas after being supplied to the fuel cell stack 12 and subjected to an electrochemical reaction in each fuel cell, is discharged from the fuel cell stack 12 through the reacted oxidizing gas discharge channel 18. After passing through the humidifier 20, it is discharged through a diluter (not shown). Further, a pressure regulating valve 22 that is an opening adjustment valve capable of adjusting the opening degree of the flow path is provided on the gas upstream side of the humidifier 20 of the reacted oxidizing gas discharge flow path 18. The pressure regulating valve 22 is an electromagnetic valve, and its opening / closing and opening degree are controlled by a fuel cell ECU (FC-ECU) 24 which is a control unit. The oxidizing gas channel 25 is constituted by the oxidizing gas supply channel 14 and the reacted oxidizing gas discharge channel 18. Further, a pressure sensor 26 that detects an air pressure that is a gas pressure is provided upstream of the pressure regulating valve 22 in the reacted oxidizing gas discharge flow path 18. The detection value of the pressure sensor 26 is input to the fuel cell ECU 24. The pressure sensor 26 can also be provided at the point Q in FIG.

  The humidifier 20 serves to humidify the air by supplying moisture contained in the air discharged from the fuel cell stack 12 to the reacted oxidizing gas discharge channel 18 to the air before being supplied to the fuel cell stack 12. Fulfill.

  On the other hand, a fuel gas supply channel 28 is provided to supply hydrogen gas, which is a fuel gas, to the fuel cell stack 12. A hydrogen gas supply source (not shown) such as a high-pressure hydrogen tank or a reformer that generates hydrogen by a reforming reaction is provided in the gas upstream portion of the fuel gas supply channel 28. The hydrogen gas supplied from the hydrogen gas supply source to the fuel gas supply channel 28 is supplied to the fuel gas internal channel on the anode side electrode side of the fuel cell stack 12 via the fuel control valve 30. The reacted hydrogen gas after being subjected to the electrochemical reaction in the fuel cell stack 12 is discharged to the reacted fuel gas discharge channel 32 and then returned to the fuel cell stack 12 again through the circulation channel 34. The reacted hydrogen gas may include unreacted hydrogen.

  A hydrogen pump 36 is provided in the circulation path 34, and the reacted hydrogen gas whose pressure has been increased by the hydrogen pump 36 is merged with the hydrogen gas supplied from the hydrogen gas supply source, and then fed back into the fuel cell stack 12. The hydrogen pump 36 is driven by a motor (not shown).

  In addition, a gas-liquid separator (not shown) is provided at the connection between the circulation path 34 and the reacted fuel gas discharge path 32. Further, a purge valve 40 controlled by the fuel cell ECU 24 is provided in the middle of the exhaust drainage flow path 38 connected to the gas-liquid separator. By opening the purge valve 40, a gas containing impurities (nitrogen, water, etc.) can be discharged from the upstream side of the reacted fuel gas discharge passage 32. The fuel gas passage 41 is constituted by the fuel gas supply passage 28 and the reacted fuel gas discharge passage 32.

  In addition, an external circuit 42 is connected to take out electric power from the fuel cell stack 12. The external circuit 42 includes a traveling motor 44 that is a load, an inverter 46, a DC / DC converter 48, and a battery 50 that is a power storage unit and is a secondary battery. That is, the traveling motor 44 is connected to the fuel cell stack 12 via the inverter 46. The fuel cell stack 12 and the battery 50 can also be connected to an auxiliary machine for generating power, such as the air compressor 16. The traveling motor 44 is, for example, a three-phase motor, and is provided as a drive source for a drive shaft (not shown) for driving the wheels of the vehicle. Further, a battery 50 is connected to the fuel cell stack 12 via a DC / DC converter 48. The battery 50 is, for example, a nickel metal hydride battery or a lithium ion battery. A capacitor may be used in place of the battery. The DC / DC converter 48 adjusts the DC voltage input from the battery 50 and supplies it to the traveling motor 44 side, or adjusts the DC voltage input from the fuel cell stack 12 and the traveling motor 44 to adjust the direct current voltage. The function to output to the side. The external circuit 42 is provided with a current sensor 52 for detecting the impedance of the fuel cell stack 12. The detection value of the current sensor 52 is input to the fuel cell ECU 24.

  The fuel cell ECU 24 controls the power generation operation of the fuel cell stack 12, and includes a microcomputer having a CPU, a memory, and the like. As shown in FIG. 1 and FIG. 2, the fuel cell ECU 24 detects signals from an accelerator sensor 54 that detects an operation amount (depression amount) of an accelerator pedal, a vehicle speed sensor (not shown) that detects a vehicle speed, and the like. An acquisition unit 56 that calculates, that is, acquires system required power based on a signal representing an operating state of an auxiliary machine such as the compressor 16 and determines a share of the system required power between the fuel cell stack 12 and the battery 50; The driving of auxiliary equipment such as the air compressor 16, the fuel control valve 30, and the hydrogen pump 36 is controlled so as to generate the fuel cell stack 12 by generating power so as to generate the required power generation amount of the fuel cell stack 12 obtained by the acquisition means 56. Power generation control means 58. That is, the acquisition unit 56 calculates the required power generation amount of the fuel cell stack 12. The acquisition unit 56 can also acquire the required power generation amount calculated by a control unit different from the fuel cell ECU 24.

  Further, as shown in FIG. 1, the fuel cell system 10 includes a gradient sensor (G sensor or the like) 60 that is a vehicle state detection unit that detects an amount of inclination of the vehicle with respect to a horizontal plane, and a charge amount (SOC) of the battery 50. And a battery ECU 62 which is a charge amount detection means to detect. That is, the gradient sensor 60 detects whether or not the vehicle is stopped or traveling on an uphill road. For example, if the detected value of the gradient sensor 60 is equal to or greater than a predetermined value, it is determined that the vehicle is located on an uphill road having a gradient equal to or greater than a threshold value.

  The battery ECU 62 is a control unit, and detects the charge amount of the battery 50 from, for example, a current input / output to / from the battery 50. Further, as shown in FIG. 2, the fuel cell ECU 24 includes a power generation stop condition determination unit 64, a power generation stop execution unit 66, a power generation stop prohibition unit 68, a drying determination unit 70, and a gas pressure increase unit 72. .

  The power generation stop condition determination unit 64 is configured to output the fuel cell stack 12 when the required power generation amount of the fuel cell stack 12 is equal to or less than a preset threshold power generation amount and the charge amount of the battery 50 is equal to or greater than a preset threshold charge amount. It is determined that the intermittent operation power generation stop condition is satisfied and the intermittent operation power generation stop condition is not satisfied, and the power corresponding to the required power generation amount is supplied to the load by the battery 50. .

  The power generation stop execution means 66 determines that the vehicle is not stopped or traveling on the uphill road from the detected value of the gradient sensor 60, and the power generation stop condition determination means 64 determines that the intermittent operation power generation stop condition is satisfied. In this case, intermittent power generation stoppage is executed. In this case, the power generation operation of the fuel cell stack 12 is always stopped. Electric power corresponding to the required power generation amount is supplied from the battery 50 to a load such as the traveling motor 44.

  Further, the power generation stop prohibiting means 68 determines from the detection value of the gradient sensor 60 that the vehicle is stopped or running on the uphill road, and the power generation stop condition determining means 64 determines that the intermittent operation power generation stop condition is not satisfied. When one or both of the above are established, the intermittent operation power generation stop is prohibited. In this case, since the fuel cell stack 12 is always in the power generation operation, even when the required power generation amount is low or zero, the fuel is generated at the minimum power generation amount that does not stop the auxiliary equipment for power generation such as the air compressor 16 or the like. The battery stack 12 generates power. For example, when the vehicle stops traveling and the required power generation amount is zero, power generation is performed with the minimum power generation amount so that the air compressor 16 can be driven at the lower limit rotational speed, which is a lower rotational speed than during normal operation. Perform idle operation.

  Further, the dry determination means 70 determines whether or not the electrolyte membrane constituting the fuel cell stack 12 is dryer than a predetermined standard set in advance. For example, the impedance of the fuel cell stack 12 is acquired from the detection value of the current sensor 52, and when the impedance is lower than a predetermined value set in advance, it is determined that the fuel cell stack 12 is not dried below a predetermined reference, On the other hand, when the impedance is equal to or higher than the predetermined value, it is determined that the fuel cell stack 12 is dryer than the predetermined reference. In addition, the dry determination of the fuel cell stack 12 can also be performed by a method other than the impedance comparison.

  Further, the gas pressure increasing means 72 determines the gas in the oxidizing gas passage 25 when it is determined by the drying determining means 70 that the electrolyte membrane constituting the fuel cell stack 12 is dryer than a predetermined standard. Increase the air pressure that is the pressure. More specifically, the gas pressure increasing means 72 controls the pressure regulating valve 22 when it is determined by the dry determination means 70 that the electrolyte membrane constituting the fuel cell stack 12 is dryer than a predetermined standard. By controlling and reducing the opening degree of the flow path of the pressure regulating valve 22, the air pressure of the oxidizing gas flow path 25 is increased to a predetermined air pressure set in advance from the normal time.

  Next, a method of controlling the power generation operation of the fuel cell stack 12 using the fuel cell system of the present embodiment will be described using the flowchart shown in FIG. In the following description, the same elements as those in FIGS. 1 and 2 are denoted by the same reference numerals. First, in step S1 of FIG. 3, the fuel cell ECU 24 determines whether or not the vehicle is stopped or traveling on an uphill road having a gradient equal to or greater than a threshold value based on the detected value of the gradient sensor 60. When it is determined that the vehicle is not stopped or traveling on an uphill road (No determination), the process proceeds to step S2. In step S2, the fuel cell ECU 24 determines whether the intermittent operation power generation stop condition is satisfied or not, and when it is determined to be satisfied (Yes determination), the process proceeds to step S3. In step S3, the power generation stop execution means 66 causes the fuel cell stack 12 to execute intermittent operation power generation stop, stop the power generation of the fuel cell stack 12, and supply the power corresponding to the required power generation amount to the load by the battery 50.

  On the other hand, when the fuel cell ECU 24 determines in step S1 that the vehicle is stopping or traveling on an uphill road having a gradient equal to or greater than the threshold value based on the detection value of the gradient sensor 60 (step S2). Thus, when one or both of the cases where the fuel cell ECU 24 determines that the intermittent operation power generation stop condition is not satisfied (No determination), the process proceeds to step S4. In step S4, the power generation stop prohibiting means 68 prohibits intermittent operation power generation stop of the fuel cell stack 12, and the fuel cell stack 12 is always generated. In step S5, it is determined whether or not the electrolyte membrane constituting the fuel cell stack 12 is dryer than a predetermined standard. If it is determined that the electrolyte membrane is dry (Yes determination), in step S6, By controlling the pressure regulating valve, the air pressure in the oxidizing gas passage 25 is set higher than normal. For example, when the idling operation is executed while the vehicle is stopped on an uphill road, the air compressor 16 continues to rotate at the lower limit rotation speed, so that the flow rate of air flowing in the fuel cell stack 12 becomes excessively high, and the fuel In some cases, the generated water in the battery stack 12 is taken away to the downstream side, and thus the fuel cell stack 12 tends to dry. According to the present embodiment, even in this case, the pressure of water vapor in the fuel cell stack 12 increases as the air pressure increases, and the amount of water carried away can be reduced. For this reason, it is possible to easily secure moisture in a necessary portion in the fuel cell stack 12.

  On the other hand, if it is determined in step S5 that the electrolyte membrane constituting the fuel cell stack 12 is not dried below the predetermined reference (No determination), the pressure regulating valve 22 is set to the normal state in step S7. By controlling, the air pressure in the oxidizing gas passage 25 is set to the normal air pressure.

  According to the fuel cell system 10 described above, the power generation operation of the fuel cell stack 12 is performed when the required power generation amount of the fuel cell stack 12 is not more than the threshold power generation amount and the charge amount of the battery 50 is not less than the threshold charge amount. In the configuration in which the operation is stopped and intermittent operation power generation is stopped by supplying the power corresponding to the required power generation amount to the load by the battery 50, the intermittent operation power generation stop is prohibited when the vehicle is stopped or traveling on the uphill road. The For this reason, there is no shortage of the amount of power generated during starting of the vehicle on the uphill road or traveling on the uphill road, and the driving force of the vehicle is not insufficient. Further, since the gradient sensor 60 detects whether or not the vehicle is stopped or traveling on the uphill road, whether or not the vehicle is stopped or running on the uphill road based on the operation amount of the accelerator pedal or the vehicle speed. Unlike the case of detecting this, it is possible to reduce the occurrence of a delay in detection, and to more effectively secure the driving force of the vehicle in accordance with the driver's intention to accelerate. For this reason, the running performance of the vehicle equipped with the fuel cell stack 12 can be improved.

  The fuel cell stack 12 is provided with an oxidizing gas passage 25 for supplying an oxidizing gas to the fuel cell stack 12 and discharging the oxidized gas after the reaction from the fuel cell stack 12, and the fuel cell ECU 24 has a predetermined electrolyte membrane constituting the fuel cell stack 12. A gas pressure increasing means 72 is included for increasing the air pressure in the oxidizing gas passage 25 when it is determined that the air is dryer than the reference. For this reason, even when the intermittent operation power generation stop is prohibited and the required power generation amount is low, the air in the oxidizing gas passage 25 is driven even when the air compressor 16 is driven and the fuel cell stack 12 tends to dry. Since the pressure rises, it is possible to suppress the removal of water in the fuel cell stack 12 by driving the air compressor 16. Therefore, it is possible to prevent a decrease in the amount of power generated due to excessive drying of the fuel cell stack 12.

  Further, since the load on the air compressor 16 increases due to the increase in air pressure, the power consumption of the air compressor 16 increases, and the power generation amount in the fuel cell stack 12 can be increased due to the increase in the required power generation amount. For this reason, the generated water in the fuel cell stack 12 further increases. As a result, it is possible to more effectively prevent the power generation amount from being reduced due to excessive drying of the fuel cell stack 12.

  In the present embodiment, the fuel cell ECU 24 includes the drying determination means 70 and the gas pressure increase means 72, and is configured to perform the steps shown in steps S to S7 in FIG. The ECU 24 does not include the drying determination unit 70 and the gas pressure increase unit 72, and the steps shown in steps S to S7 in FIG. 3 can be omitted.

  Further, in the present embodiment, the fuel cell system 10 includes a navigation system 74 (FIG. 1) that is a vehicle state detection unit, and the vehicle is stopped or traveling when the vehicle has a gradient greater than or equal to a threshold by the navigation system 74. It can also be determined whether or not it is in the middle. The navigation system 74 is mounted on a vehicle, detects the current position of the vehicle by associating position information detected by a GPS receiver or the like with road information stored in advance in a storage unit, It is detected whether the vehicle is stopping or traveling on an uphill road having a gradient equal to or greater than a threshold value. As the vehicle state detection means, only the gradient sensor 60 may be used as described above, or the accuracy may be improved by using the gradient sensor 60 and the navigation system 74, and only the navigation system 74 is used. May be used. Other configurations and operations are the same as those in the present embodiment.

  DESCRIPTION OF SYMBOLS 10 Fuel cell system, 12 Fuel cell stack, 14 Oxidation gas supply flow path, 16 Air compressor, 18 Reacted oxidation gas discharge flow path, 20 Humidifier, 22 Pressure regulation valve, 24 Fuel cell ECU, 25 Oxidation gas flow path, 26 Pressure sensor, 28 Fuel gas supply flow path, 30 Fuel control valve, 32 Reacted fuel gas discharge flow path, 34 Circulation path, 36 Hydrogen pump, 38 Exhaust drain flow path, 40 Purge valve, 41 Fuel gas flow path, 42 External circuit, 44 traveling motor, 46 inverter, 48 DC / DC converter, 50 battery, 52 current sensor, 54 accelerator sensor, 56 acquisition means, 58 power generation control means, 60 gradient sensor, 62 battery ECU, 64 power generation stop condition determination Means, 66 power generation stop execution means, 68 power generation stop prohibiting means, 70 drying determination means, 2 gas pressure raising means, 74 a navigation system.

Claims (5)

A fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidizing gas;
A control unit for controlling the power generation operation of the fuel cell,
A fuel cell system used in a vehicle,
Vehicle state detection means for detecting whether the vehicle is stopped or traveling on an uphill road, including a gradient sensor or a navigation system;
Charge amount detecting means for detecting the charge amount of the power storage unit,
The control unit
Obtaining means for obtaining the required power generation amount of the fuel cell;
When the required power generation amount of the fuel cell is equal to or less than the threshold power generation amount and the charge amount of the power storage unit is equal to or greater than the threshold charge amount, the power generation operation of the fuel cell is stopped and the power corresponding to the required power generation amount is stored. Determining means for determining that the intermittent operation power generation stop condition is satisfied to be supplied to the load,
Execution means for executing intermittent operation power generation stop when the vehicle is not stopped or traveling on an uphill road and the determination means determines that the intermittent operation power generation stop condition is satisfied;
Prohibiting means for prohibiting intermittent operation power generation stop when one or both of the fact that the vehicle is stopped or traveling on an uphill road and the determination means determines that the intermittent operation power generation stop condition is not established are established; A fuel cell system comprising: The fuel cell system according to claim 1, wherein
Provided with an oxidizing gas flow path for supplying oxidizing gas to the fuel cell and discharging the oxidized gas after reaction from the fuel cell,
The control unit
A fuel cell system comprising gas pressure increasing means for increasing the gas pressure in the oxidizing gas flow path when it is determined that the electrolyte membrane constituting the fuel cell is dryer than a predetermined standard. The fuel cell system according to claim 2, wherein
With an opening adjustment valve that can adjust the opening of the flow path downstream of the gas from the fuel cell of the oxidizing gas flow path,
Gas pressure increase means
A fuel cell system characterized in that when it is determined that the electrolyte membrane constituting the fuel cell is dryer than a predetermined reference, the opening adjustment valve is controlled to reduce the opening of the flow path. A fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidizing gas;
A control unit for controlling the power generation operation of the fuel cell,
A fuel cell system used in a vehicle,
Provided with an oxidizing gas flow path for supplying oxidizing gas to the fuel cell and discharging the oxidized gas after reaction from the fuel cell,
The control unit
A fuel cell system comprising gas pressure increasing means for increasing the gas pressure in the oxidizing gas flow path when it is determined that the electrolyte membrane constituting the fuel cell is dryer than a predetermined standard. The fuel cell system according to claim 4, wherein
With an opening adjustment valve that can adjust the opening of the flow path downstream of the gas from the fuel cell of the oxidizing gas flow path,
Gas pressure increase means
A fuel cell system characterized in that, when it is determined that the electrolyte membrane constituting the fuel cell is dryer than a predetermined reference, the opening degree adjustment valve is controlled to reduce the opening degree of the flow path.

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