JP2008251315A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply a sufficient driving force to the shut-off valve and enable its stable operation while suppressing reduction in efficiency by a simple and convenient system in a fuel cell system. <P>SOLUTION: The fuel cell system includes atmospheric pressure chambers 71, 81, pressurized chambers 72, 82 pressurized by fuel gas, and valve closing springs 73a, 83a for biasing force to valves in the valve closing direction, and by the pressure difference between the atmospheric pressure chambers 71, 81 and the pressurized chambers 72, 82, the biasing force of the valve closing springs 73a, 83a are driven to open/close the shut-off valves 70, 80. When stopping a fuel cell 13, a hydrogen gas supply valve 43 and an exhaust valve 55 are closed, and by consuming the fuel gas remained in the fuel cell 13 by power generation reaction, and by reducing pressure in a pressurizing hydrogen gas supply pipe 61, the shut-off valves 70, 80 are closed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a configuration of a fuel cell system, and more particularly to a drive system for a shutoff valve.

  A fuel cell generates electricity by an electrochemical reaction between a fuel and an oxidant, and includes a membrane electrode assembly (MEA) in which a fuel side electrode and an oxidant side electrode are disposed on opposite sides of an electrolyte made of an ion exchange membrane. A fuel separator having a fuel supply channel for supplying fuel to the fuel side electrode; and an oxidant separator having an oxidant supply channel for supplying an oxidant to the oxidant side electrode. Yes. Various gases are used for fuel and oxidizer. For example, hydrogen is used for fuel, and oxygen-containing air is used for oxidizer. Power is generated by electrochemical reaction and water is generated on the oxidizer electrode side. Many of these formats are used.

  In such a fuel cell, when the operation is stopped, air as an oxidant gas remains in the oxidant supply channel on the oxidant electrode side, and in the fuel supply channel on the fuel side electrode. The fuel gas, hydrogen, remains. On the other hand, in the stopped fuel cell, hydrogen as the fuel gas moves to the oxidant electrode side through the ion exchange membrane, and conversely, oxygen in the air as the oxidant gas passes through the ion exchange membrane to the fuel electrode. Cross leak that moves to the side. When this cross leak occurs, hydrogen and oxygen are combined by a chemical reaction different from the power generation reaction to produce water. When oxygen in the air on the oxidant electrode side moves to the fuel electrode side, nitrogen that does not react with hydrogen remains on the oxidant electrode, and unreacted hydrogen remains on the fuel electrode side. Further, since hydrogen gas and oxygen gas react to generate water by the reaction, the pressure inside the stopped fuel cell decreases (for example, see Patent Document 1).

  In Patent Document 1, the fuel electrode and the oxidant electrode are sealed with the on / off valves while the fuel cell is stopped, and the decrease in the wetness of the electrolyte membrane is suppressed by the water generated by the reaction due to the cross leak. A method is described. Patent Document 2 describes a system that pneumatically drives a shut-off valve that seals a fuel cell, and a method of supplying driving air via an accumulator in this system.

  In addition, if there is a pressure difference between the oxidant electrode side and the fuel electrode side of the fuel cell, a problem may occur in the membrane electrode assembly electrolyte membrane, and the pressure between the oxidant electrode side and the fuel electrode side may be set to a predetermined value. It may be necessary to adjust to an acceptable range. For this reason, a system has been proposed in which an oxidant gas is introduced into a control valve so that the pressures of the oxidant gas and the fuel gas are equal (see Patent Document 3).

JP 2004-6166 A Japanese Patent Laid-Open No. 2000-3717 JP 2005-353305 A

  In the prior art of Patent Document 2, the shut-off valve is driven by the differential pressure between the pressure of air supplied from the pneumatic compressor to the fuel cell or reformer and the pressure of the reformed gas or air discharged from the fuel cell. Therefore, the driving force may be insufficient. In particular, since the air side uses the differential pressure generated by the pressure loss of the air flow path in the fuel cell as a drive source of the shut-off valve, trying to increase the overall efficiency by reducing the pressure loss on the air side of the fuel cell The driving force of the shut-off valve will be insufficient. Further, when the flow rate of air flowing to the fuel cell is reduced by the load, the differential pressure is reduced, and the driving force is further reduced.

  The prior art described in Patent Document 3 is to introduce an oxidant gas into a pressure control system to drive a control valve. However, the oxidant gas may contain moisture, and the system component equipment accumulates moisture. Corrosion may occur, and oxidant gas remaining in the control valve after the fuel cell is stopped may generate moisture due to dew condensation, which freezes and causes system malfunction.

  An object of the present invention is to supply a sufficient driving force to a shut-off valve with a simple system and to enable stable operation.

  The fuel cell system of the present invention is provided at a fuel cell that generates power by an electrochemical reaction between a fuel gas and an oxidant gas, and at an inlet and an outlet of the oxidant gas of the fuel cell. And an oxidant gas shut-off valve that is kept closed when the fuel cell is stopped, wherein each oxidant gas shut-off valve is a fuel gas supplied to the fuel cell. It has each valve opening and closing drive mechanism driven by.

  In the fuel cell system of the present invention, the valve opening / closing drive mechanism includes an atmospheric pressure chamber that communicates with the atmosphere, a pressurization chamber that is partitioned from the atmospheric pressure chamber and pressurized by fuel gas, and a valve that exerts a force in the valve closing direction. The oxidant gas shut-off valve is driven to open and close by the pressure difference between the atmospheric pressure chamber and the pressurizing chamber and the urging force of the valve closing spring. When there is no pressure difference from the pressure chamber, the oxidant gas shut-off valve is preferably kept closed by the valve closing spring, and the fuel gas supply for supplying fuel gas to the fuel cell A fuel gas supply valve that opens and closes the fuel gas supply path, a discharge valve that discharges the reacted gas from the fuel cell and discharges the reacted gas, a fuel cell, and a fuel gas A fuel gas supply passage for pressurization connected between the supply valve and the power generation of the fuel cell And a control unit that opens and closes the fuel gas supply valve and the discharge valve. When the fuel cell is stopped, the control unit closes the fuel gas supply valve and the discharge valve and remains in the fuel cell. It is also preferable to have a valve closing operation means for causing the generated fuel gas to be consumed by a power generation reaction so that the pressure of the pressurizing fuel gas supply path is made lower than the pressure at the time of stop and each oxidant gas shut-off valve is closed. It is.

  In the fuel cell system of the present invention, the valve opening / closing drive mechanism includes an atmospheric pressure chamber that communicates with the atmosphere, a pressurization chamber that is partitioned from the atmospheric pressure chamber and pressurized by fuel gas, and a force in the valve opening direction. The oxidant gas shut-off valve is driven to open and close by the pressure difference between the atmospheric pressure chamber and the pressurizing chamber and the urging force of the valve opening spring. When there is no pressure difference from the pressure chamber, it is also preferable to hold the oxidant gas shut-off valve in an open state by a valve opening spring, and a fuel gas supply for supplying fuel gas to the fuel cell A fuel gas supply valve that opens and closes the fuel gas supply path, a discharge valve that discharges the reacted gas from the fuel cell and discharges the reacted gas, a fuel cell, and a fuel gas A fuel gas supply passage for pressurization connected between the supply valve and the power generation of the fuel cell And a control unit that opens and closes the fuel gas supply valve and the discharge valve. When the fuel cell is stopped, the control unit closes the fuel gas supply valve and the discharge valve and remains in the fuel cell. It is also preferable that the fuel gas is consumed by a power generation reaction, the pressure of the fuel gas supply passage for pressurization is made negative, and each oxidant gas shut-off valve is closed. The fuel gas supply path is provided with a pressurization fuel gas supply path shut-off valve, the control section opens and closes the pressurization fuel gas supply path shut-off valve, and the control section closes each oxidant gas shut-off valve by a valve closing operation means. It is also preferable to include a repressurization means for closing the pressurization fuel gas supply path shut-off valve, opening the fuel gas supply valve and supplying the fuel gas to the fuel cell and pressurizing it after Each oxidant gas shut-off valve was provided on the fuel cell side A seat, disposed in the counter-fuel cell side of the valve seat, that has a valve body which is attracted to the valve seat by the negative pressure in the fuel cell during the stop of the fuel cell, it is also suitable as.

  In the fuel cell system of the present invention, it is preferable to have a buffer tank for accumulating the fuel gas supplied to the pressurizing chamber, and a fuel gas supply path for supplying the fuel gas to the fuel cell, and a fuel cell. A discharge path for discharging the gas after the reaction, and a recirculation path for connecting the discharge path and the fuel gas supply path, the pressurizing fuel gas supply path from the connection position of the recirculation path and the fuel gas supply path It is also preferable that it is connected to the fuel gas supply path upstream of the fuel gas, and it is also preferable to have a gate valve provided in the fuel gas supply path for pressurization, and the recirculation path And a fuel gas supply path between the connection position of the pressurization fuel gas supply path and the fuel gas supplied to the pressurization chamber is hydrogen. High-pressure fuel gas accumulated in the supply source It is a low-pressure fuel gas vacuum, it is also preferable.

  The present invention provides an effect that a sufficient driving force can be supplied to the shut-off valve with a simple system and a stable operation can be performed.

  Preferred embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the fuel cell system 11 according to the present embodiment is supplied with hydrogen gas as a fuel gas and air as an oxidant gas to generate power by an electrochemical reaction, and to the fuel cell 13. A hydrogen tank 41 for storing hydrogen gas to be stored, an air compressor 17 for compressing air supplied to the fuel cell 13, and a humidifying module 15 for humidifying air supplied to the fuel cell 13. The air compressor 17 and the humidification module 15 are connected by a compressed air supply pipe 27, and the humidification module 15 and the fuel cell 13 include an air inlet pipe 29 that guides the air humidified in the humidification module to the air inlet of the fuel cell 13. The air discharged from the air outlet of the fuel cell 13 is connected to an air outlet pipe 31 that guides the air to the humidification module. The humidification module 15 is connected to an air discharge pipe 33 that discharges air to the outside. Further, a bypass pipe 35 that connects the compressed air supply pipe 27 and the air discharge pipe 33 is provided, and the compressed air supply pipe 27 is provided with a pressure sensor 26 that measures pressure. The air compressor 17 is driven by a motor 19, and the air whose temperature has increased by the air compressor 17 is cooled by the intercooler 21 and then supplied to the humidification module 15.

  The air inlet pipe 29 is provided with an air inlet cutoff valve 70, and the air outlet pipe 31 is provided with an air outlet cutoff valve 80. An air pressure control valve 25 is provided between the air outlet of the fuel cell 13 in the air outlet pipe 31 and the air outlet shut-off valve 80, and the fuel cell 13 is provided in the air outlet pipe 31 upstream of the air pressure control valve 25. A pressure sensor 37 for measuring the outlet air pressure is provided. The bypass pipe 35 is provided with a bypass flow rate adjustment valve 23.

  The hydrogen tank 41 is connected to the fuel cell 13 by a hydrogen gas supply pipe 45 which is a fuel gas supply path. The fuel cell 13 is provided with a gas discharge pipe 47 for discharging the gas after reaction with air from the fuel cell 13. Yes. The hydrogen gas supply pipe 45 has a hydrogen gas supply valve 43 that depressurizes the high-pressure hydrogen gas stored in the hydrogen tank 41 and opens and closes the hydrogen gas supply pipe 45 to regulate the supply of hydrogen gas to the fuel cell 13. Is provided. The gas discharge pipe 47 is connected to a diluter 59 provided in parallel to the atmospheric discharge pipe 34, and the gas after the reaction is diluted with air and then discharged from the atmospheric discharge pipe 34 to the atmosphere together with the exhaust air. The gas discharge pipe 47 is provided with a discharge valve 55 that opens and closes the gas discharge pipe 47 to adjust the release of the gas after reaction to the atmosphere.

  Between the gas discharge pipe 47 and the hydrogen gas supply pipe 45, a recirculation pipe 49 is provided for recirculating part of the reacted gas discharged from the fuel cell 13 to the hydrogen gas supply pipe 45. The recirculation pipe 49 is configured to connect between a connection point 46 between the fuel cell 13 and the hydrogen gas supply valve 43 and a branch point 48 between the fuel cell 13 and the discharge valve 55. The recirculation pipe 49 is provided with a circulation pump 51 that recirculates the reacted gas from the gas discharge pipe 47 to the hydrogen gas supply pipe 45.

  Hydrogen gas for driving the air inlet shutoff valve 70 and the air outlet shutoff valve 80 is supplied to a branch point 44 between the hydrogen gas supply valve 43 of the hydrogen gas supply pipe 45 and the connection point 46 of the recirculation pipe 49. A pressurizing hydrogen gas supply pipe 61 is connected. The pressurizing hydrogen gas supply pipe 61 is connected to a buffer tank 63 that stores driving hydrogen gas for the shut-off valves 70 and 80. The buffer tank 63 and the shut-off valves 70 and 80 are connected to the shut-off valve driving hydrogen. A pressure sensor 67 is attached to the shut-off valve driving hydrogen gas pipe 65 connected by the gas pipe 65.

  The air inlet shut-off valve 70 includes a valve body 70b and a drive unit 70a. The valve body 70 b includes a valve seat 78 and a valve body 76 in a casing, and a valve rod 77 is attached to the valve body 76. The drive unit 70 a is partitioned into two pressure chambers by a diaphragm 74 attached to the casing and a drive plate 75 connected to the diaphragm 74. The upper pressure chamber in FIG. 1 is an atmospheric pressure chamber 71 having an atmosphere communication hole 79 communicating with the atmosphere, and the lower pressure chamber in FIG. 1 is connected to a hydrogen gas pipe 65 for driving a shutoff valve from the buffer tank 63. A pressurizing chamber 72 is pressurized by the hydrogen gas supplied from the buffer tank 63. The pressure plate 72 side of the drive plate 75 is connected to the valve body 76 via a valve rod 77, and the drive plate 75 is attached to the wall surface of the atmospheric pressure chamber 71 on the atmospheric pressure chamber 71 side of the drive plate 75. A valve closing spring 73a that is pressed toward the valve seat 78 is provided. The air outlet shut-off valve 80 also has the same structure as the air inlet shut-off valve 70, and includes a valve main body 80b and a drive unit 80a. The valve main body 80b includes a valve seat 88 and a valve body 86. An atmospheric pressure chamber 81 having an atmospheric communication hole 89 communicating with the pressure chamber 82, a pressurizing chamber 82 to which the shutoff valve driving hydrogen gas pipe 65 from the buffer tank 63 is connected, and a valve body 86 through a valve rod 87. A driving plate 85, a diaphragm 84, and a valve closing spring 83a are provided.

  The pressure sensor 26 of the compressed air supply pipe 27, the pressure sensor 37 of the air outlet of the fuel cell 13, and the pressure sensor 67 of the shutoff valve driving hydrogen gas pipe 65 are connected to the control unit 100, and the detection signal is transmitted to the control unit 100. It is comprised so that it may be input. The motor 19 of the air compressor 17, the bypass flow rate adjustment valve 23, the air pressure adjustment valve 25, the hydrogen gas supply valve 43, the discharge valve 55, and the circulation pump 51 are connected to the control unit 100 and controlled. It is comprised so that it may operate | move by the instruction | command of the part 100.

  When the hydrogen gas pressure supplied from the buffer tank 63 is high, the air inlet shut-off valve 70 and the air outlet shut-off valve 80 pressurize the pressurizing chambers 72 and 82 with the hydrogen gas, and the drive plates 75 are pressurized with the pressure. , 85 are pushed up to the atmospheric pressure chambers 71, 81 side to be opened, and when the hydrogen gas pressure supplied from the buffer tank is low, the drive plates 75, 85 are moved by the valve closing springs 73 a, 83 a. The valve bodies 76 and 86 are pressed against the valve seats 78 and 88 and the air shut-off valves 70 and 80 are closed. For this reason, when the hydrogen gas pressure is lost, each shut-off valve is closed.

  Hereinafter, the operation of the fuel cell system 11 of the present embodiment will be described. When the fuel cell system 11 is in a stopped state, the air inlet shutoff valve 70 and the air outlet shutoff valve 80 of the fuel cell 13 are closed, and the air side electrode of the fuel cell 13 is shut off from the outside air. Further, the hydrogen side electrode is in a state of being disconnected from the outside air and the hydrogen tank 41.

  When the start command for the fuel cell system 11 is issued, the control unit 100 starts the motor 19 of the air compressor 17 to increase the rotation speed of the air compressor 17 and opens the bypass flow rate adjustment valve 23 to The compressed air supplied from the compressor 17 to the compressed air supply pipe 27 flows from the bypass pipe 35 to the air discharge pipe 33 and is discharged from the atmospheric discharge pipe 34 to the atmosphere.

  Further, in response to the start command of the fuel cell, the control unit 100 opens the hydrogen gas supply valve 43 and injects the hydrogen gas stored in the high-pressure hydrogen tank 41 into the hydrogen electrode side of the fuel cell 13 while reducing the pressure. Is increased toward the operating pressure. When the hydrogen side electrode of the fuel cell 13 is pressurized with hydrogen gas, the hydrogen gas supply pipe 61 for pressurization, the buffer tank 63, and the hydrogen gas pipe 65 for driving the shutoff valve connected to the hydrogen gas supply pipe 45 are also hydrogenated. Is injected and the pressure rises. Then, this hydrogen enters the pressurizing chambers 72 and 82 of the shutoff valves 70 and 80 from the shutoff valve driving hydrogen gas pipe 65 and increases the pressure. As the pressure in the pressurizing chambers 72 and 82 increases, a pressure difference is generated between the atmospheric pressure chambers 71 and 81, and the force in the valve opening direction applied to the drive plates 75 and 85 increases as the pressure difference increases. Go. When the force in the valve opening direction applied to the drive plate 75 due to the pressure difference between the pressurizing chambers 72 and 82 and the atmospheric pressure chambers 71 and 81 becomes larger than the force in the valve closing direction of the valve closing springs 73a and 83a, Each shut-off valve 70, 80 is opened.

  When the shut-off valves 70 and 80 are opened, the compressed air compressed by the air compressor 17 flows into the fuel cell 13. When the shut-off valves 70 and 80 are opened and air can flow into the fuel cell 13, the control unit 100 reduces the opening of the bypass flow rate adjustment valve 23 and increases the opening of the air pressure adjustment valve 25. Then, the pressure control of the air side electrode of the fuel cell 13 is transferred to the air pressure control valve 25, and the pressure control of the air side electrode is performed by the air pressure control valve 25.

  When both the hydrogen side electrode and the air side electrode are pressurized, the control unit 100 controls the power generation of the fuel cell 13 to the power generation output according to the output request, and continues the operation. The pressure on the hydrogen side electrode is adjusted by a hydrogen gas supply valve 43. Depending on the load of the fuel cell 13, the hydrogen gas supply valve 43 may be closed, but since the hydrogen gas for driving the shutoff valves 70 and 80 is supplied via the buffer tank 63, a stable pressure can be obtained. The driving hydrogen gas is supplied, and the shutoff valves 70 and 80 can be kept open.

  When a stop command for the fuel cell 13 is issued, the control unit 100 closes the hydrogen gas supply valve 43 to stop the injection of hydrogen gas into the fuel cell 13, and closes the discharge valve 55 to close the outside air and the hydrogen side electrode. Shut off. Further, the control unit 100 closes the air pressure adjustment valve 25 to stop the inflow of air into the fuel cell 13 and opens the bypass flow rate adjustment valve 23 to open the air compressed by the air compressor 17 from the bypass pipe 35. It is made to flow through the air discharge pipe 33. The pressure on the air side electrode of the fuel cell 13 is controlled by the bypass flow rate adjustment valve 23.

  After stopping the inflow of hydrogen gas and air into the fuel cell 13, the control unit 100 causes hydrogen remaining in the hydrogen side electrode of the fuel cell 13 to react with air, thereby reducing the pressure at the hydrogen side electrode. Perform hydrogen consumption operation. Since the hydrogen gas supply valve 43 and the discharge valve 55 are closed and the hydrogen side electrode is in a sealed state, when the remaining hydrogen is consumed by the hydrogen consumption operation, the pressure of the hydrogen side electrode is reduced. It will decline. Since the hydrogen side electrode of the fuel cell 13 communicates with the hydrogen gas supply pipe 45 and the pressurization hydrogen gas supply pipe 61, the pressure of the pressurization hydrogen gas supply pipe 61 also decreases. Further, when the pressure of the pressurizing hydrogen gas supply pipe 61 is lowered, the pressure of the buffer tank 63 and the shutoff valve driving hydrogen gas pipe 65 is also lowered, and accordingly, the pressurizing chambers 72 and 82 of the shutoff valves 70 and 80 are reduced. The pressure will drop. And if the valve opening direction force by the differential pressure between each pressurization chamber 72,82 and each atmospheric pressure chamber 71,81 becomes smaller than the force of the valve closing direction of valve closing spring 73a, 83a, Each shut-off valve 70, 80 is closed. When the shutoff valves 70 and 80 are closed, the control unit 100 stops the hydrogen consumption operation.

  When the shutoff valves 70 and 80 are closed, the air side electrode of the fuel cell 13 is cut off from the atmosphere, but the air remaining on the air side electrode of the fuel cell 13 and the hydrogen side electrode remain. By further reaction with the hydrogen that is present, the pressure on both the air side electrode and the hydrogen side electrode decreases, and the pressure on both the air side electrode and the hydrogen side electrode becomes negative. The valve seats 78 and 88 of the shut-off valves 70 and 80 are provided on the fuel cell 13 side. When the air side electrode of the fuel cell 13 becomes negative pressure, the valve bodies 76 and 86 are valve seated by the negative pressure. The shut-off valves 70 and 80 are held in the closed state together with the force in the valve closing direction of the valve closing springs 73a and 83a.

  In the present embodiment, the pressure of the pressurizing chambers 72 and 82 of the shut-off valves 70 and 80 is increased using the pressure of hydrogen gas stored in the high-pressure hydrogen tank 41 to open the shut-off valves 70 and 80. The valve is configured so that the pressure in the pressurizing chambers 72 and 82 of the shutoff valves 70 and 80 is reduced by the hydrogen consumption operation when the fuel cell 13 is stopped, and the shutoff valves 70 and 80 are closed. Therefore, there is no need for a valve for opening and closing the driving gas for opening and closing each shut-off valve 70 and 80, and the opening and closing operation of each shut-off valve 70 and 80 can be performed with a simple configuration. . In addition, there is no need for power for maintaining the valve open state or power for maintaining the valve closed state, and it is possible to suppress a decrease in efficiency of the fuel cell system 11. Moreover, since the pressure of the hydrogen tank 41 in the high pressure state is reduced and used as the driving gas, the driving pressure can be set freely and a sufficient driving force can be ensured. Furthermore, the provision of the buffer tank 63 provides an effect that the pressure fluctuation can be suppressed and a stable driving pressure can be obtained.

  In the present embodiment, the connecting position of the pressurizing hydrogen gas supply pipe 61 is the branch point 44 upstream of the connection point 46 of the recirculation pipe 49 to the hydrogen gas supply pipe 45. Moisture that has entered from the air side electrode is less likely to enter the pressurizing hydrogen gas supply pipe 61 of each shutoff valve 70, 80. For this reason, dry hydrogen gas can be supplied to the pressurizing chambers 72 and 82 of the shut-off valves 70 and 80 as driving gas, and the shut-off valves 70 and 80 are frozen due to condensation at a low temperature. It is possible to reduce the occurrence of malfunction and to stabilize the operation of the fuel cell system 11.

  As shown in FIG. 2, in order to make this effect more effective, a gate valve is provided between the connection point 46 between the recirculation pipe 49 and the hydrogen gas supply pipe 45 and the branch point 44 of the pressurizing hydrogen gas supply pipe 61. 57 may be provided so that the gas in the recirculation pipe 49 does not enter the hydrogen gas supply pipe 61 for pressurization. Further, the gas in the recirculation pipe 49 enters the pressurizing chambers 72 and 82 by the gate valve 56 provided in the pressurizing hydrogen gas supply pipe 61 or the gate valve 58 provided in the shut-off valve driving hydrogen gas pipe 65. You may comprise so that it may not exist. These gate valves 56, 57, and 58 may be connected to the control unit 100, and may be configured to be closed when the opening / closing operation of the shut-off valves 70 and 80 is completed, and to be opened when activated.

  Another embodiment of the present invention will be described with reference to FIG. Parts similar to those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. In another embodiment shown in FIG. 3, valve opening springs 73b and 83b are provided in place of the valve closing springs 73a and 83a provided in the shut-off valves 70 and 80 of the embodiment described above. It is what. One end of each of the valve opening springs 73b and 83b is attached so as to abut against the wall surface of each pressurizing chamber 72 and 82, and the other end is abutted against each of the drive plates 75 and 85. It is comprised so that the force pushed up toward a valve opening direction may be given.

  The air inlet shut-off valve 70 and the air outlet shut-off valve 80 according to the present embodiment are configured so that when the hydrogen gas pressure supplied from the buffer tank 63 is a negative pressure, the pressurization chambers 72 and 82 are brought into a negative pressure state by the hydrogen gas. When each of the drive plates 75 and 85 presses the valve bodies 76 and 86 against the valve seats 78 and 88 due to the negative pressure to be closed, and the hydrogen gas pressure supplied from the buffer tank 63 is a positive pressure, The drive plates 75 and 85 are pushed up by the valve-opening springs 73b and 83b and the positive pressure, and the air shut-off valves 70 and 80 are opened. For this reason, when the hydrogen gas pressure disappears, each shut-off valve opens.

  Next, the operation of the fuel cell system 11 of this embodiment will be described. When the fuel cell system 11 is in a stopped state, the air inlet shutoff valve 70 and the air outlet shutoff valve 80 of the fuel cell 13 are closed, and the air side electrode of the fuel cell 13 is shut off from the outside air. Further, the hydrogen side electrode is in a state of being disconnected from the outside air and the hydrogen tank 41. Since the air side electrode and the hydrogen side electrode of the fuel cell 13 have negative pressures, the pressurizing chambers 72 and 82 of the shutoff valves 70 and 80 also have negative pressure and force in the valve closing direction on the valve bodies. The valve bodies 76 and 86 are attracted to the valve seats 78 and 88 by the negative pressure of the air side electrode of the fuel cell 13, and a force in the valve closing direction is applied. Since the force in the valve closing direction is larger than the force in the opening direction of the valve opening springs 73b and 83b, the valve is closed.

  When the fuel cell system 11 is started, both the air side electrode and the hydrogen side electrode are pressurized, so that the pressure in the pressurizing chambers 72 and 82 of the shutoff valves 70 and 80 becomes positive and the drive plate 75, A force in the valve opening direction is applied to 85. When the force in the valve opening direction and the force in the valve opening direction by the valve opening springs 73b and 83b are larger than the force in the valve closing direction applied to the valve bodies 76 and 86, the shutoff valves 70 and 80 are opened. When the valve is opened, air flows into the air side electrode of the fuel cell 13, the air side electrode also becomes positive pressure, and a force in the valve opening direction is also applied to the valve bodies 76 and 86. Accordingly, the shutoff valves 70 and 80 are held open while the fuel cell system is in operation.

  Similar to the previous embodiment. When the fuel cell 13 is stopped, the hydrogen gas supply valve 43 and the discharge valve 55 are closed to perform the hydrogen consumption operation of the fuel cell 13 to reduce the pressure on the hydrogen side electrode. In this embodiment, the hydrogen consumption operation of the fuel cell 13 is performed until the pressure detected by the pressure sensor 67 provided in the shut-off valve driving hydrogen gas pipe 65 becomes negative. When the negative pressure of the shut-off valve driving hydrogen gas pipe 65 becomes lower than a predetermined negative pressure, the control unit 100 determines that the shut-off valves 70 and 80 are closed, and the hydrogen consumption Stop operation.

  This embodiment also has the same effect as the above-described embodiment.

  In this embodiment, a hydrogen gas supply shutoff valve for shutoff valve driving is attached to the hydrogen gas supply pipe 61 for pressurization, and hydrogen consumption is continued until the shutoff valve drive hydrogen gas pipe 65 communicated with the hydrogen side electrode becomes negative pressure. After the operation and the shut-off valves 70 and 80 are closed, the shut-off valve driving hydrogen gas supply shut-off valve attached to the pressurization hydrogen gas supply pipe 61 is closed to pressurize the shut-off valves 70 and 80. The negative pressure state of 72 and 82 may be maintained, and the hydrogen gas supply valve 43 may be opened to repressurize the hydrogen side electrode and then stop. Thus, by repressurizing the hydrogen side electrode of the fuel cell 13 to increase the hydrogen concentration of the hydrogen side electrode after stopping, the performance deterioration of the fuel cell 13 due to low hydrogen can be prevented. Play.

It is a figure which shows the system | strain structure of a fuel cell system in embodiment of the fuel cell system which concerns on this invention. It is a figure which shows the system | strain structure of the modification of embodiment of FIG. In other embodiment of the fuel cell system which concerns on this invention, it is a figure which shows the system configuration | structure of a fuel cell system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 Fuel cell system, 13 Fuel cell, 15 Humidification module, 17 Air compressor, 19 Motor, 21 Intercooler, 23 Bypass flow control valve, 25 Air pressure control valve, 26, 37, 67 Pressure sensor, 27 Compressed air supply pipe, 29 Air inlet pipe, 31 Air outlet pipe, 33 Air exhaust pipe, 34 Air discharge pipe, 35 Bypass pipe, 41 Hydrogen tank, 43 Hydrogen gas supply valve, 44 Branch point, 45 Hydrogen gas supply pipe, 46 Connection point, 47 Gas Discharge pipe, 48 branch point, 49 recirculation pipe, 51 circulation pump, 55 discharge valve, 56-58 gate valve, 59 diluter, 61 hydrogen gas supply pipe for pressurization, 63 buffer tank, 65 hydrogen gas pipe for shutoff valve drive , 70 Air inlet shut-off valve, 70a, 80a Drive unit, 70b, 80b Valve body, 71, 81 Atmospheric pressure chamber, 72 82 Pressurizing chamber, 73a, 83a Valve closing spring, 73b, 83b Valve opening spring, 74, 84 Diaphragm, 75, 85 Drive plate, 76, 86 Valve body, 77, 87 Valve rod, 78, 88 Valve seat, 79,89 Air communication hole, 80 Air outlet shut-off valve, 100 Control unit.

Claims (12)

A fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidant gas, and is provided at the inlet and outlet of the oxidant gas of the fuel cell. The fuel cell is kept open during operation, and the fuel cell is stopped. A fuel cell system including an oxidant gas cutoff valve held in a closed state,
Each oxidant gas shut-off valve has a valve opening / closing drive mechanism that is driven by a fuel gas supplied to the fuel cell. The fuel cell system according to claim 1,
The valve opening / closing drive mechanism includes an atmospheric pressure chamber that communicates with the atmosphere, a pressure chamber that is partitioned from the atmospheric pressure chamber and pressurized by fuel gas, and a valve closing spring that biases the valve in a valve closing direction. The oxidant gas shut-off valve is driven to open and close by the pressure difference between the atmospheric pressure chamber and the pressurizing chamber and the biasing force of the valve closing spring, and the pressure difference between the atmospheric pressure chamber and the pressurizing chamber When there is no fuel, the fuel cell system is characterized in that the oxidant gas cutoff valve is held in a closed state by a valve closing spring. The fuel cell system according to claim 2, wherein
A fuel gas supply valve that is provided in a fuel gas supply path for supplying fuel gas to the fuel cell and opens and closes the fuel gas supply path, and a discharge path that discharges the gas after reaction from the fuel cell to supply the gas after reaction. A discharge valve for discharging, and a fuel gas supply passage for pressurization connected between the fuel cell and the fuel gas supply valve,
A control unit for performing power generation control of the fuel cell and opening / closing operation of the fuel gas supply valve and the discharge valve;
When the fuel cell is stopped, the control unit closes the fuel gas supply valve and the discharge valve, and consumes the fuel gas remaining in the fuel cell by a power generation reaction, thereby adjusting the pressure of the pressurizing fuel gas supply path. Having a valve closing operation means for lowering the pressure at the time of stopping and closing each oxidant gas cutoff valve;
A fuel cell system. The fuel cell system according to claim 1,
The valve opening / closing drive mechanism includes an atmospheric pressure chamber that communicates with the atmosphere, a pressurization chamber that is partitioned from the atmospheric pressure chamber and pressurized by fuel gas, and a valve opening spring that biases the valve in a valve opening direction. The pressure difference between the atmospheric pressure chamber and the pressurization chamber is controlled by the pressure difference between the atmospheric pressure chamber and the pressurization chamber, and the urging force of the valve opening spring opens and closes the oxidant gas shut-off valve. When there is no fuel, the fuel cell system is characterized in that the oxidant gas shut-off valve is held open by a valve opening spring. The fuel cell system according to claim 4, wherein
A fuel gas supply valve that is provided in a fuel gas supply path for supplying fuel gas to the fuel cell and opens and closes the fuel gas supply path, and a discharge path that discharges the gas after reaction from the fuel cell to supply the gas after reaction. A discharge valve for discharging, and a fuel gas supply passage for pressurization connected between the fuel cell and the fuel gas supply valve,
A control unit for performing power generation control of the fuel cell and opening / closing operation of the fuel gas supply valve and the discharge valve;
When the fuel cell is stopped, the control unit closes the fuel gas supply valve and the discharge valve, and consumes the fuel gas remaining in the fuel cell by a power generation reaction, thereby adjusting the pressure of the pressurizing fuel gas supply path. Having a closing operation means for closing each oxidant gas cutoff valve as a negative pressure;
A fuel cell system. The fuel cell system according to claim 5, wherein
A pressurization fuel gas supply path is provided with a pressurization fuel gas supply path cutoff valve,
The control unit opens and closes the pressurization fuel gas supply path cutoff valve,
The control unit closes each oxidant gas shut-off valve by the valve closing operation means, then closes the pressurization fuel gas supply path shut-off valve, opens the fuel gas supply valve, and supplies and adds fuel gas to the fuel cell. Providing re-pressurizing means for pressing,
A fuel cell system. The fuel cell system according to any one of claims 4 to 6,
Each oxidant gas shut-off valve is a valve seat provided on the fuel cell side and a valve seat disposed on the anti-fuel cell side of the valve seat, and is sucked into the valve seat by the negative pressure in the fuel cell while the fuel cell is stopped Having a body,
A fuel cell system. The fuel cell system according to claim 1, wherein
A fuel cell system comprising a buffer tank for accumulating fuel gas supplied to a pressurizing chamber. The fuel cell system according to any one of claims 1 to 8,
A fuel gas supply path for supplying fuel gas to the fuel cell, a discharge path for discharging the reacted gas from the fuel cell, and a recirculation path for connecting the discharge path and the fuel gas supply path,
The fuel cell system, wherein the pressurizing fuel gas supply path is connected to a fuel gas supply path upstream of the fuel gas with respect to a connection position between the recirculation path and the fuel gas supply path. The fuel cell system according to claim 9, wherein
Having a gate valve provided in the fuel gas supply passage for pressurization;
A fuel cell system. The fuel cell system according to claim 9 or 10, wherein
Having a gate valve provided in the fuel gas supply path between the connection position of the recirculation path and the connection position of the fuel gas supply path for pressurization;
A fuel cell system. The fuel cell system according to any one of claims 1 to 11,
The fuel cell system, wherein the fuel gas supplied to the pressurizing chamber is a low-pressure fuel gas obtained by decompressing the high-pressure fuel gas accumulated in the hydrogen supply source.

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