JP2006086006A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control hydrogen gas supply pressure to a fuel cell according to a state of a fuel cell system. <P>SOLUTION: In the fuel cell system having a hydrogen pressure control valve 6 in a hydrogen gas supply passage 21, operation characteristics of the hydrogen pressure control valve 6 are changed according to the state of the fuel cell system. For example, when the state of the fuel cell system is in a foreign matter deposition state in the hydrogen gas passage 21 and the foreign matter is exhausted, the secondary side discharge pressure of the hydrogen pressure control valve 6 is made high, and in a hydrogen gas leakage state from the hydrogen gas supply passage 21, the secondary side discharge pressure of the hydrogen pressure control valve 6 is made low. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system that generates electricity from hydrogen and oxygen, and more particularly to an improvement in a fuel (hydrogen) gas supply system.

  In a fuel cell, hydrogen gas as a fuel gas and air (oxygen) as an oxidizing gas are electrochemically reacted, and electricity generated in the process is taken out to the outside. A fuel cell is formed by stacking a required number of cells each having a fuel electrode (anode) supplied with hydrogen gas and an air electrode (cathode) supplied with air on both sides of an electrolyte membrane. For example, in a polymer electrolyte fuel cell (PEFC) suitable for in-vehicle use, a polymer ion exchange membrane is used as an electrolyte membrane. Since this ion exchange membrane is as thin as several tens of microns, the pressure difference between the hydrogen pressure on the fuel electrode side and the air pressure on the air electrode side (interelectrode differential pressure) should not be excessive in order to prevent damage. There is a need to.

Therefore, for example, in the invention described in Japanese Patent Application Laid-Open No. 2003-68334, a hydrogen circulation line is provided with a pump so that hydrogen supplied from a hydrogen pressure reducing valve and hydrogen off-gas are combined and supplied to the fuel cell. The pressure regulating valve for hydrogen gas is driven by the air pressure of the air supply pump to keep the differential pressure between the fuel gas and the air pressure within a predetermined range.
JP 2003-68334 A

  However, according to the above-described configuration, although the inter-electrode differential pressure is maintained within a predetermined range, the supply pressure range of the hydrogen gas pressure regulating valve is affected by the dynamic range of the discharge pressure of the air compressor. . Further, since a mechanical pressure regulating valve structure using a diaphragm to which air pressure is applied to one side is used, the hydrogen gas pressure supplied to the fuel cell cannot be controlled independently.

  In order to improve the durability of the fuel cell, it is preferable that the hydrogen gas supply pressure to the fuel cell is low. However, if it is always low, the foreign matter accumulated in the fuel gas supply passage cannot be removed and the power generation state becomes unstable. There are problems such as that it takes time to stabilize the power generation when starting the fuel cell or returning to intermittent operation, flooding or the like occurs, the cell voltage decreases, and there is a certain limit to improving the accuracy of hydrogen leak detection. On the other hand, when the hydrogen gas supply pressure is constantly high, there are problems such as not only the above-described decrease in durability but also an increase in the amount of discharge to the outside at the time of water gas leakage and the possibility of damaging the fuel cell at the time of failure.

  Accordingly, an object of the present invention is to solve the above problem by controlling the fuel gas supply pressure to the fuel cell in accordance with the state of the fuel cell system.

In order to achieve the above object, a fuel cell system of the present invention includes a fuel gas supply passage for supplying fuel gas from a fuel gas source to the fuel cell, and a pressure of the fuel gas from the fuel gas source provided in the fuel gas supply passage. A fuel cell system comprising a pressure regulating device that regulates pressure and discharges downstream. The fuel cell system further comprises changing means for changing an operating characteristic of the pressure regulating device according to the state of the fuel cell system.
With this configuration, the fuel gas pressure can be controlled in accordance with the state of the fuel cell system.
The operating characteristic of the pressure regulator is changed by, for example, detecting a physical quantity related to the state of the fuel cell system by the state detecting unit and performing the changing unit based on the output.

  In the fuel cell system according to the present invention, when the state of the fuel cell system is a foreign matter accumulation state in the fuel gas supply passage and the foreign matter is discharged, the state of the fuel cell system is started when the fuel cell is started or returned from intermittent operation. When the fuel cell is in the start-up state, the fuel cell system state is the cell voltage and the cell voltage is below the predetermined value, and the fuel cell system state detects the fuel gas leak When the fuel gas leak detection is performed, the operating characteristic of the pressure regulator is changed so as to increase the discharge pressure on the secondary side of the pressure regulator.

By adopting such a configuration, the durability of the fuel cell is maintained in a low pressure operation during normal times, while when foreign matter accumulates in the fuel gas supply passage and the power generation state becomes unstable, the operation is switched to a high pressure operation to remove the foreign matter. By extruding and removing from the fuel gas supply system, the power generation state can be stabilized.
In addition, even when it takes time to stabilize power generation, such as when starting a fuel cell or when returning from intermittent operation, it is possible to achieve early stabilization by increasing the amount of fuel gas supplied to the fuel cell. Can be planned.
Further, when the cell voltage becomes equal to or lower than a predetermined value, flooding, which is a factor in reducing the cell voltage, can be eliminated by promoting discharge of generated water to the outside of the cell.
Further, when performing fuel gas leak detection in the fuel cell system, it is possible to improve the leak detection accuracy by temporarily increasing the fuel gas pressure in the fuel gas supply passage.

  In the fuel cell system of the present invention, the state of the fuel cell system is the state of fuel gas leakage from the fuel gas supply passage and the fuel gas is in the state of leakage, or the state of the fuel cell system is the fuel gas pressure. When the fuel gas pressure is deviated from the target pressure by a predetermined value or more, the operating characteristics of the pressure regulator are changed so as to reduce the discharge pressure on the secondary side of the pressure regulator.

With this configuration, when the fuel gas is leaking, the fuel gas pressure on the fuel cell inlet side can be made lower than that during normal operation, and the amount of fuel gas released to the outside can be reduced.
In addition, when the fuel gas pressure deviates from the target pressure by a predetermined value or more, the fuel cell is protected even if a malfunction occurs in the pressure regulator by limiting the operating range of the fuel cell to a certain load or less. can do.

  In the present invention, the pressure regulator has a structure capable of adjusting the secondary discharge pressure by introducing a pressurized fluid from the outside, and the changing means is a controller for supplying pressurized fluid from the outside to the pressure regulator. A pressurized fluid supply path, a discharge valve capable of discharging pressurized fluid outside the supply path in the middle of the pressurized fluid supply path, and a control means for controlling the opening degree of the discharge valve according to the system state of the fuel cell. It is good also as a structure provided.

  In such a configuration, it is possible to adjust the secondary-side discharge pressure of the pressure regulating device by increasing or decreasing the discharge amount of the pressurized fluid supplied from the outside to the pressure regulating device in the middle of the pressurized fluid supply path. . For this reason, it is possible to control the secondary discharge pressure that is not limited by the supply source pressure of the pressurized fluid.

  According to the present invention, the fuel gas pressure can be controlled according to the state of the fuel cell system. In particular, recovery from an unstable power generation state, early stabilization of power generation at the time of fuel cell start-up or return start from intermittent operation, improved accuracy of fuel gas leak detection, reduction of the amount released to the outside at the time of fuel gas leak, The fuel cell can be protected after the failure occurs.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram schematically illustrating a basic configuration of a fuel cell system according to an embodiment of the present invention. In the figure, air as an oxidizing gas is supplied to an air supply port of the fuel cell 1 through an air supply path 11. An air compressor 3, an air filter 2, and a humidifier (not shown) are provided in the air supply path 11, and the air passing through the air filter 2 is pressurized to an appropriate pressure and is necessary for the electrolyte membrane of the fuel cell. Water is replenished.
The air off gas discharged from the fuel cell 1 is discharged to the outside through the exhaust path 12. The exhaust passage 12 is provided with a pressure adjustment valve (not shown) as a pressure regulator for adjusting the pressure of the supply air (air pressure), and the air pressure to the fuel cell 1 is maintained at a predetermined value. The setting of the air pressure is performed by adjusting the air compressor 3 and the pressure regulating valve by a control unit (control means) 50 configured by a control computer system.

Hydrogen gas as fuel gas is supplied from a hydrogen supply source (fuel gas source) (not shown) to a hydrogen supply port of the fuel cell 1 through a hydrogen gas supply path (fuel gas supply path) 21. Examples of the hydrogen supply source include a high-pressure hydrogen tank, a tank using a hydrogen storage alloy, a methanol fuel reformer, and the like, and includes a pressure regulating valve, a pump, and the like. The hydrogen gas supply path 21 is provided with a hydrogen pressure regulating valve (pressure regulating device) 6 that depressurizes (regulates) the pressure of the hydrogen gas from the hydrogen supply source and discharges it downstream.
Hydrogen gas (fuel gas) not consumed by the fuel cell 1 is discharged to the hydrogen circulation path 22 as hydrogen off-gas. The hydrogen circulation path 22 is provided with a hydrogen pump 5, and the hydrogen off-gas pressurized by the hydrogen pump 5 is returned to the hydrogen gas supply path 21 on the downstream side of the hydrogen pressure regulating valve 6 and merged with the hydrogen gas. The fuel cell 1 is reused. The operation of the hydrogen pump 5 is controlled by the control unit 50.

The hydrogen pressure regulating valve 6 is, for example, a mechanical pressure regulating valve using a diaphragm biased by a spring, and an air pressure propagation path (pressurized fluid supply path) 31 branched from the air supply path 11 is connected to the diaphragm. Thus, a pressure using the air pressure to the fuel cell 1 as a pressure source is applied.
The diaphragm is displaced according to the differential pressure between the applied pressure and the pressure of the spring and the supply hydrogen pressure at the inlet of the fuel cell 1, and the valve opening degree (opening rate) of the hydrogen pressure regulating valve 6 on the hydrogen gas supply path 21 is changed. Set. As a result, the secondary discharge pressure of the hydrogen pressure regulating valve 6 varies, so that the supply hydrogen pressure at the inlet of the fuel cell 1 is also adjusted to be within a predetermined pressure range by the pressure applied to the hydrogen pressure regulating valve 6.
Thus, the hydrogen pressure regulating valve 6 has a structure capable of adjusting the secondary side discharge pressure by introducing the supply air (pressurized fluid) from the air compressor 3.

In the air pressure propagation path 31, an orifice 4 and a buffer tank 8 for preventing pulsation are provided in order from the upstream side, and an exhaust path 32 branches from between the buffer tank 8 and the hydrogen pressure regulating valve 6. The exhaust path 32 is provided with an exhaust valve (exhaust valve) 7 for reducing the air pressure to the hydrogen pressure regulating valve 6, and the valve opening rate of the exhaust valve 7 is continuously from fully closed to fully opened by the control unit 50. Or adjusted in multiple stages.
When the exhaust valve 7 is in the fully closed state (opening rate = 0), the air pressure by the air compressor 3 is applied as it is to the hydrogen pressure regulating valve 6 as it is. When the exhaust valve 7 is in a fully opened state (opening rate = 100%), the supply air from the air compressor 3 is exhausted from the exhaust passage 32 almost as it is, and the air pressure is not applied to the hydrogen pressure regulating valve 6. That is, the air pressure to the fuel cell 1 and the supply hydrogen pressure are irrelevant (independent). With respect to the valve opening ratio between the two, the air pressure by the air compressor 3 is used as a pressure source, and the valve opening ratio of the exhaust valve 7 is appropriately set to obtain a desired applied pressure. This is supplied as an applied pressure to the diaphragm of the hydrogen pressure regulating valve 6.
As described above, in the present embodiment, the air pressure propagation path 31 that supplies the supply air from the air compressor 3 to the hydrogen pressure regulating valve 6, and the exhaust that can exhaust the supply air outside the propagation path in the middle of the air pressure propagation path 31. The change means of this invention is comprised including the valve 7 and the control part 50 which controls the opening degree of the exhaust valve 7 according to the system state of the fuel cell 1.

Next, the relationship between the opening / closing operation of the exhaust valve 7 and the air pressure applied to the hydrogen pressure regulating valve 6 that changes in conjunction therewith will be described with reference to FIGS.
As shown in FIG. 2, when the valve opening rate of the exhaust valve 7 is lowered (at the time of pressure increase), the air A from the air compressor 3 distributed from the air supply path 11 to the air pressure propagation path 31 side is on the exhaust path 32 side. Since it flows to the hydrogen pressure regulating valve 6 side more than being exhausted, the pressure applied to the hydrogen pressure regulating valve 6 increases. Accordingly, the discharge pressure on the secondary side of the hydrogen pressure regulating valve 6 increases, and the supply hydrogen pressure at the inlet of the fuel cell 1 also increases.

On the other hand, as shown in FIG. 3, when the valve opening rate of the exhaust valve 7 is increased (when the pressure is lowered), the air A from the air compressor 3 distributed from the air supply path 11 to the air pressure propagation path 31 side is exhausted. Since the exhaust gas flows and exhausts more on the path 32 side, the pressure applied to the hydrogen pressure regulating valve 6 becomes lower. Therefore, the discharge pressure on the secondary side of the hydrogen pressure regulating valve 6 is lowered, and the supply hydrogen pressure at the inlet of the fuel cell 1 is also lowered.
In this way, the air pressure as the pressure supply source is adjusted to be reduced by the exhaust valve 7 and supplied to the hydrogen pressure regulating valve 6 as an applied pressure, so that the inlet side of the fuel cell 1 as shown in the target pressure map of FIG. The hydrogen pressure supplied to the air compressor can be adjusted to a desired value within a predetermined range without being linked to the air pressure, in other words, without being restricted by the supply pressure of the air compressor 3 that is the air supply source.

Supplementing this FIG. 4, in this fuel cell system, from the mechanical operating characteristic X inherently provided in the structure of the hydrogen pressure regulating valve 6, the operating characteristic X is added to the air pressure component (arrow line) by the air compressor 3. The target supply hydrogen pressure at the inlet of the fuel cell 1 can be controlled within the range up to the operation characteristic Y with the addition of).
Such control is performed during normal operation, when a foreign substance is mixed into the hydrogen gas supply path 21, and when the fuel cell is in failure such as when hydrogen gas leaks from a hydrogen flow path such as the fuel cell 1 or the hydrogen gas supply path 21. The target supply hydrogen pressure at the inlet 1 is set in advance in a map (see the foreign matter mixing characteristics and failure characteristics in FIG. 4), and the applied air pressure to the hydrogen pressure regulating valve 6 is set to such a target supply hydrogen pressure. In order to obtain it, it implement | achieves by carrying out duty control of the exhaust valve 7. FIG.

Next, one control operation by the control unit 50 will be described with reference to the flowchart of FIG. This control operation is executed by an interruption that occurs when a predetermined event or a specific event occurs in the control program. First, in step S1, it is determined whether foreign matter is mixed in the hydrogen gas supply path 21 or not. This determination is made based on, for example, the output value of a pressure sensor (state detection means) installed at an appropriate place in the hydrogen gas supply path 21.
When it is determined that foreign matter is mixed in the hydrogen gas supply path 21 (step S1; YES), the process proceeds to step 3, and the target pressure map at the time of foreign matter is referred to from the target pressure map shown in FIG. The target supply hydrogen pressure at the fuel cell 1 inlet is set. On the other hand, if it is determined that there is no foreign matter mixed (step S1; NO), the process proceeds to step 10, where the target supply hydrogen pressure at the inlet of the fuel cell 1 is set with reference to the normal target pressure map.

When the target supply hydrogen pressure at the inlet of the fuel cell 1 is set as described above, the process proceeds to step 5 and the exhaust valve 7 is duty-controlled to obtain the applied air pressure to the hydrogen pressure regulating valve 6 so as to be the target supply hydrogen pressure. Then, the hydrogen pressure regulating valve 6 is controlled.
That is, when foreign matter is mixed in the hydrogen gas supply passage 21, the operating characteristics of the hydrogen pressure regulating valve 6 are set so that the discharge pressure on the secondary side of the hydrogen pressure regulating valve becomes higher than normal as shown in FIG. By changing and improving the flow of hydrogen gas in the hydrogen gas supply path 21, accumulated foreign matter can be pushed out and removed from the hydrogen flow path, so that an unstable power generation state due to foreign matter contamination can be eliminated at an early stage. Can be stabilized.

In the fuel cell system of the present invention, the following determination may be performed instead of the foreign object contamination determination performed in step 1 of FIG.
[First fail judgment]
Fail determination is performed based on the presence or absence of hydrogen leakage from a hydrogen flow path such as the hydrogen gas supply path 21. Then, in step 3 that is executed when it is determined that a failure (hydrogen leakage exists), the target supply hydrogen pressure at the inlet of the fuel cell 1 is determined by referring to the target pressure map at the time of failure from the target pressure increase shown in FIG. Set lower than normal.
As a result, the operating characteristics of the hydrogen pressure regulating valve 6 are changed so that the secondary side discharge pressure of the hydrogen pressure regulating valve 6 is lower than normal. Therefore, when hydrogen leakage from the hydrogen flow path is detected, The amount of hydrogen gas released into the gas can be reduced.

When performing hydrogen leak detection in such a fuel cell system, prior to that, the discharge pressure on the secondary side of the hydrogen pressure regulating valve 6 may be increased. For example, referring to a target pressure map for hydrogen leak detection as shown in FIG. 6, the target supply hydrogen pressure at the inlet of the fuel cell 1 is set to be higher than normal in a predetermined section (see the broken line portion in FIG. 6).
As a result, the operating characteristics of the hydrogen pressure regulating valve 6 are changed so that the secondary side discharge pressure of the hydrogen pressure regulating valve 6 becomes higher than normal. Therefore, when hydrogen leakage is detected from the hydrogen flow path, By increasing the pressure temporarily, it is possible to improve the leak detection accuracy.

[Second fail judgment]
Fail determination is performed from the hydrogen pressure in the hydrogen flow path such as the hydrogen gas supply path 21. Specifically, as shown in FIG. 7, an actual measurement value (broken line portion shown in FIG. 7) by a pressure sensor arranged at an appropriate position in the hydrogen gas supply path 21 is equal to or greater than a predetermined value from the target value (solid line portion). If there is a divergence, it is determined as a failure. Then, in step 3 that is executed when it is determined as a failure, for example, the target pressure map at the time of failure shown in FIG. To do.
Also in this case, since the operation characteristic of the hydrogen pressure regulating valve 6 is changed so that the secondary side discharge pressure of the hydrogen pressure regulating valve 6 is lower than usual, there is a possibility that the hydrogen pressure regulating valve 6 is abnormal. In this case, the operating range of the fuel cell 1 is limited to a certain load or less, and the fuel cell 1 can be protected.

[Cell voltage judgment]
It is determined whether or not the cell voltage monitor value of the fuel cell 1 has decreased to a predetermined value. Then, in step 3 that is executed when the determination result is “YES; reduced to a predetermined value”, for example, a target pressure map similar to that shown in FIG. Set the pressure higher than normal.
As a result, the operation characteristics of the hydrogen pressure regulating valve 6 are changed so that the secondary side discharge pressure of the hydrogen pressure regulating valve 6 becomes higher than normal, and therefore, when there is a possibility of flooding, it is eliminated. Thus, the cell voltage drop can be prevented.

[Startup judgment or intermittent operation return judgment]
It is determined whether the current system state of the fuel cell system is when the fuel cell 1 is activated or when the fuel cell system is returned from intermittent operation. Then, in step 3 executed when the determination result is “YES; when starting or returning from intermittent operation”, for example, the fuel cell 1 is referred to by referring to a target pressure map similar to that shown in FIG. The target supply hydrogen pressure at the inlet is set higher than normal.
As a result, the operating characteristics of the hydrogen pressure regulating valve 6 are changed so that the secondary side discharge pressure of the hydrogen pressure regulating valve 6 becomes higher than normal. Therefore, at the time of starting the fuel cell 1 or returning from the intermittent operation Startability is improved.

In order to further improve the startability, a check valve 41 may be provided on the upstream side of the buffer tank 8 in the pneumatic propagation path 31 as shown in FIG. FIG. 9 is a graph showing the supply hydrogen pressure at the inlet of the fuel cell 1 and the pressure change downstream of the buffer tank 8 in this case.
With this configuration, even when the pressure of the air compressor 3 is low, such as when the fuel cell 1 is started or when returning from the intermittent operation, the air pressure propagation before the fuel cell 1 is stopped or before the intermittent operation is started. The pressure in the passage 31 is accumulated in the buffer tank 8 and the downstream side thereof.
Therefore, even when the fuel cell 1 is started or intermittently restarted, the initial applied pressure to the hydrogen pressure regulating valve 6 is secured as shown by the one-dot chain line in FIG. Compared to the case where there is no check valve 41 shown, the rising of the supply hydrogen pressure at the inlet of the fuel cell 1 is quickened, and further improvement in startability can be realized.

  In the configuration of the above embodiment, the supply air pressure to the fuel cell 1 is used as a pressure source, and this is used as the driving pressure of the diaphragm of the hydrogen pressure regulating valve 6, but the pressure propagation medium (for example, An inert gas such as nitrogen gas or a liquid) may be pressurized or depressurized and applied to the diaphragm of the hydrogen pressure regulating valve 6. By propagating the air pressure to the diaphragm of the hydrogen pressure regulating valve 6 through an inert gas (pressure propagation medium), the oxidation (deterioration) of the hydrogen pressure regulating valve 6 is suppressed, and the life of the hydrogen pressure regulating valve 6 is extended or is reliable. Improvement can be achieved.

The configuration for changing the operating characteristic of the pressure regulator is basically the configuration of the above-described claim 9 or the embodiment as long as the fluid pressurized to a predetermined pressure is reduced in the middle and introduced into the pressure regulator. It is not limited to. For example, the operating state of the pump (increase or decrease the discharge pressure by controlling the rotational speed) may be changed according to the state of the fuel cell system.
Further, the operating characteristics may be changed without introducing the pressurized fluid into the pressure regulator. For example, instead of introducing a pressurized fluid into the atmospheric chamber of the pressure regulator (regulator), the diaphragm may be moved directly or indirectly by an electric actuator.

1 is a block diagram showing a basic configuration of a fuel cell system according to an embodiment of the present invention. It is explanatory drawing explaining that the operating characteristic of a hydrogen pressure regulation valve is changed according to the valve opening rate (small) of an exhaust valve. It is explanatory drawing explaining that the operating characteristic of a hydrogen pressure regulation valve is changed according to the valve opening rate (large) of an exhaust valve. It is a map which shows the relationship between the driving | running state of a fuel cell, and a target supply hydrogen pressure. It is a flowchart explaining how to change the operating characteristic of the hydrogen pressure regulating valve. It is a map for setting the target supply hydrogen pressure at the time of hydrogen leak detection. It is explanatory drawing explaining how a failure determination is performed from the difference of the measured value of hydrogen pressure, and a target value. It is a block diagram which shows the basic composition of the fuel cell system which added the check valve to the pneumatic propagation path. FIG. 9 is an explanatory diagram for explaining that the startability of the fuel cell is improved by the configuration of FIG. 8.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell, 6 Hydrogen pressure regulation valve (pressure regulator), 7 Exhaust valve (discharge valve, a part of change means), 21 Hydrogen gas supply path (fuel gas supply path), 31 Pressure propagation path (Pressurized fluid supply path) , Part of changing means), 50 control unit (control means, part of changing means)

Claims (9)

A fuel gas supply passage for supplying fuel gas from the fuel gas source to the fuel cell;
A pressure regulator that regulates the pressure of the fuel gas from the fuel gas source and discharges it downstream, provided in the fuel gas supply passage,
A fuel cell system comprising changing means for changing an operating characteristic of the pressure regulator according to a state of the fuel cell system. Comprising a state detecting means for detecting a physical quantity relating to the state of the fuel cell system;
2. The fuel cell system according to claim 1, wherein the changing means changes the operating characteristic of the pressure regulator based on the output of the state detecting means.   When the state of the fuel cell system is a foreign matter accumulation state in the fuel gas supply passage and the foreign matter is discharged, the changing means changes so as to increase the discharge pressure on the secondary side of the pressure regulator. The fuel cell system according to claim 1 or 2.   When the state of the fuel cell system is when the fuel cell is started or when returning from intermittent operation is started and the fuel cell is in the activated state, the changing means increases the discharge pressure on the secondary side of the pressure regulator. The fuel cell system according to claim 1, wherein the fuel cell system is changed.   When the state of the fuel cell system is a fuel gas leakage state from the fuel gas supply passage and the fuel gas is in a leakage state, the changing means is changed to lower the discharge pressure on the secondary side of the pressure regulator. The fuel cell system according to claim 1, wherein:   When the state of the fuel cell system is a cell voltage and the cell voltage is equal to or lower than a predetermined value, the changing means changes the discharge pressure on the secondary side of the pressure regulator to be higher. The fuel cell system according to claim 1 or 2.   When the fuel cell system is in the state of fuel gas pressure and the fuel gas pressure deviates from the target pressure by a predetermined value or more, the changing means is changed to lower the discharge pressure on the secondary side of the pressure regulator. The fuel cell system according to claim 1, wherein:   When the state of the fuel cell system is a state of detecting a fuel gas leak and a state of detecting a fuel gas leak, the changing means should be changed to increase the discharge pressure on the secondary side of the pressure regulator. The fuel cell system according to claim 1, wherein:   The pressure regulator has a structure capable of adjusting the secondary discharge pressure by introducing pressurized fluid from the outside, and the changing means is a pressurized fluid supply path for supplying pressurized fluid from the outside to the pressure regulator And a discharge valve capable of discharging the pressurized fluid outside the supply path in the middle of the pressurized fluid supply path, and a control means for controlling the opening degree of the discharge valve in accordance with the system state of the fuel cell. The fuel cell system according to claim 1, wherein:

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