JP2010232167A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of architecting a fuel cell system of high efficiency and simplicity. <P>SOLUTION: The fuel cell system is constituted of a pressure adjuster 1 capable of controlling pressure of a fuel supplied to a fuel cell 8, a first check valve 2 connected to the outlet of the fuel cell 8, a second check valve 3 connected to the inlet of the fuel cell 8, and circulating passages 10, 11 installed between the first check valve 2 and the second check valve 3. The pressure of the fuel supplied to the fuel cell 8 is elevated by the pressure adjuster 1, the fuel discharged from the fuel cell 8 is stored in the circulating passages 10, 11 positioned downstream of the fuel cell 8 via the first check valve 2, supply of the fuel to the fuel cell 8 is stopped or reduced by the pressure adjuster 1, and the fuel stored in the circulating passages 10, 11 is circulated to the fuel cell 8 via the second check valve 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel cell system, and more particularly to a circulating fuel cell system in which unreacted fuel gas and oxidant gas discharged from an outlet of a fuel cell are resupplied to the inlet of the fuel cell, that is, the gas is circulated.

  A fuel cell is an energy conversion device that utilizes an electrochemical reaction that produces water from hydrogen and oxygen. Hydrogen and oxygen (air) are supplied to extract electricity from the fuel cell, respectively. In general, hydrogen and oxygen are supplied in excess of the amount consumed by the fuel cell. This is to prevent removal of water generated by the fuel cell reaction, damage to the fuel cell due to insufficient supply gas amount, and reduction in power output. However, if the unreacted gas is exhausted out of the system as it is, the energy of the exhausted gas cannot be used effectively. Therefore, the energy efficiency of the fuel cell system is reduced. In order to effectively utilize the energy of unreacted gas, a circulating fuel cell system that re-supplys the gas discharged from the fuel cell outlet to the fuel cell inlet using a pump or an ejector, that is, circulates the gas. Many have been devised.

JP 2004-095528 A JP 2003-178777 A

  However, when the circulation is performed using the pump, the efficiency of the system is lowered because the pump itself consumes a part of the power generated by the fuel cell in order to circulate the gas. Further, since the pump has a movable part, it becomes a source of vibration and noise. The advantages of a fuel cell compared to a conventional heat engine power generator include high efficiency, quietness, no moving parts, etc., but adopting a pump as one of the components of a fuel cell system Therefore, the advantage of the fuel cell is qualitatively offset.

  The ejector can circulate gas without consuming electric power, but the main disadvantage is that the operating range is relatively narrow. There have been proposed ejectors that can operate over a wide range by providing a movable needle, and a system that expands the operating range of the system by using a plurality of ejectors (for example, Patent Documents 1 and 2). However, since these methods cover the narrow characteristics inherent in the ejector with control and system configuration, the control and system become complicated.

  As described above, in order to construct a highly efficient and simple fuel cell system, a circulation system different from the conventional one is desired.

  Accordingly, one object of the present invention is to provide a technique capable of constructing a highly efficient and simple fuel cell system. The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  In order to solve the above problems, a fuel cell system according to the present invention includes a pressure regulator capable of arbitrarily controlling the pressure of fuel supplied to the fuel cell, and a first check valve connected to the outlet of the fuel cell. The second check valve connected to the inlet of the fuel cell and a circulation path provided between the first check valve and the second check valve. Then, the pressure of the fuel supplied to the fuel cell is raised by the pressure regulator, and the fuel discharged from the fuel cell is stored in a circulation path located downstream of the fuel cell via the first check valve, and the fuel cell The fuel supply to the fuel cell is stopped or reduced by the pressure regulator, and the fuel stored in the circulation path is circulated to the fuel cell via the second check valve.

  Similarly, another fuel cell system according to the present invention includes a pressure regulator capable of arbitrarily controlling the pressure of the oxidant supplied to the fuel cell, a first check valve connected to the outlet of the fuel cell, A second check valve connected to the inlet of the fuel cell, and a circulation path provided between the first check valve and the second check valve. Then, the pressure of the oxidant supplied to the fuel cell is raised by the pressure regulator, and the oxidant discharged from the fuel cell is stored in a circulation path located downstream of the fuel cell via the first check valve, The supply of the oxidant to the fuel cell is stopped or reduced by the pressure regulator, and the oxidant stored in the circulation path is circulated to the fuel cell via the second check valve.

  Similarly, both the fuel electrode (hydrogen electrode) and the oxidant electrode (oxygen electrode) can be simultaneously circulated by the above-described means.

  According to the present invention, gas can be circulated without using a pump or an ejector, so that a highly efficient and simple fuel cell system can be constructed.

It is a figure which shows the structural example of the fuel cell system by one embodiment of this invention. In the fuel cell system shown in FIG. 1, it is a figure which shows the time change of the control signal to a pressure regulator, the pressure of a fuel cell, the flow volume of a 1st check valve, and the flow volume of a 2nd check valve. It is a figure which shows the flow of the gas in the period I of FIG. It is a figure which shows the flow of the gas in the period II of FIG. In the fuel cell system shown in FIG. 1, the control signal to the pressure regulator, the pressure of the fuel cell, the flow rate of the first check valve when the pressure is controlled to decrease at an arbitrary speed in the period II. It is a figure which shows the time change of the flow volume of a 2nd check valve. It is a figure which shows the flow of the gas in the period II of FIG. In the fuel cell system shown in FIG. 1, the control signal to the pressure regulator and the pressure of the fuel cell when the control signal is controlled so as to rapidly decrease at a pressure decrease rate of a certain level or higher in the period II. It is a figure which shows the time change of the flow volume of a 1st check valve, and the flow volume of a 2nd check valve. FIG. 7 shows an example in which control is performed so that the control signal increases from an arbitrary initial value during which the control signal becomes discontinuous when the control signal shifts from the control period II to the control period I in FIG. FIG. It is a figure which shows the example in the case of performing control so that a control signal always changes continuously in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

  FIG. 1 is a diagram showing a configuration example of a fuel cell system according to an embodiment of the present invention. First, an example of the configuration of the fuel cell system according to the present embodiment will be described with reference to FIG.

  In this embodiment, the fuel cell includes a hydrogen electrode to which a fuel such as hydrogen or methane gas is supplied and an oxygen electrode to which an oxidant such as oxygen or air is supplied. In FIG. Only the pole side is shown. Therefore, it is possible to adopt the same configuration as that in FIG. 1 on the oxygen electrode side. In that case, oxygen or air is supplied instead of hydrogen.

  As shown in FIG. 1, the fuel cell system according to the present embodiment includes, for example, a fuel cell 8 that generates power by an electrochemical reaction between hydrogen and oxygen, a hydrogen cylinder 7 that stores fuel gas, and a high pressure of the hydrogen cylinder 7. A pressure regulator 1 for depressurizing and supplying hydrogen to the fuel cell 8, a pressure sensor 5 for detecting the pressure at the inlet of the fuel cell 8 (fuel cell inlet 6), and a pressure regulator based on the detection result of the pressure sensor 5 1, a control device 9 that controls 1, a first check valve 2 through which gas (unreacted fuel gas) discharged from the outlet of the fuel cell 8 (fuel cell outlet 12) passes, and discharged from the fuel cell outlet 12 A circulation path 10 and a circulation path 11 for circulating the generated gas to the fuel cell inlet 6, a gas-liquid separator 4 for separating the gas discharged from the fuel cell outlet 12 and moisture, and a circulation path 11. Passed gas passes And a like second check valve 3. Here, the circulation path 10 and the circulation path 11 are pipes having a certain internal volume.

  The pressure regulator 1 is connected between the hydrogen cylinder 7 and the fuel cell inlet 6, the pressure sensor 5 is connected to the fuel cell inlet 6, and the first check valve 2 is between the fuel cell outlet 12 and the circulation path 10. The gas-liquid separator 4 is connected between the circulation path 10 and the circulation path 11, and the second check valve 3 is connected between the circulation path 11 and the fuel cell inlet 6. The first check valve 2 is a valve for preventing backflow, and gas flows only from the fuel cell outlet 12 toward the circulation path 10. Similarly, the second check valve 3 is a valve for preventing a backflow, and the gas flows only from the circulation path 11 toward the fuel cell inlet 6. In FIG. 1, an example of hydrogen as the fuel gas has been described, but other fuel gas cylinders such as methane gas may be used instead of the hydrogen cylinder 7.

  FIG. 2 shows the control signal for the pressure regulator 1 output from the control device 9 during operation of the fuel cell system of FIG. 1, the fuel cell pressure, the flow rate of the gas passing through the first check valve 2, and the second reverse Each time change of the flow rate of the gas passing through the stop valve 3 is shown. In FIG. 2, the fuel cell pressure is the pressure at the inlet of the fuel cell 8 detected by the pressure sensor 5, but is substantially equal to the pressure of the fuel gas in the fuel cell.

  As shown in FIG. 2, when the fuel cell system according to the present embodiment operates and the fuel cell 8 is generating electric power, the period I and the period II are alternately repeated. FIG. 3 shows how the gas flows in the period I, and FIG. 4 shows how the gas flows in the period II.

  In the period I, the control signal output from the control device 9 to the pressure regulator 1 increases linearly, so that the pressure of the fuel cell also increases linearly by the action of the pressure regulator 1. At this time, as shown in FIG. 3, the gas flows in the manner of pressure regulator 1 → fuel cell inlet 6 → fuel cell 8 → fuel cell outlet 12 → first check valve 2 → circulation path 10 → gas-liquid separator 4. → The circulation path 11 As shown in FIG. 2, since the pressure of the fuel cell 8 is controlled to increase linearly, if the gas consumption in the fuel cell 8 is constant, the flow rate of gas flowing through the first check valve 2 is constant. It becomes. Since the pressure in the circulation path 11 is lower than the pressure at the fuel cell inlet 6 by the pressure loss of the fuel cell 8, the first check valve 2, the gas-liquid separator 4 and the piping, the second check valve 3 is closed. It becomes a state. As a result, gas does not flow through the second check valve 3. When the pressure of the fuel cell 8 increases due to the action of the pressure regulator 1 and the fuel cell pressure detected by the pressure sensor 5 reaches the preset upper limit pressure, the control device 9 stops outputting the control signal. (Or make the output signal low enough).

  When the output of the control signal from the control device 9 is stopped, the gas supply via the pressure regulator 1 is stopped, but the fuel cell 8 continues to consume gas, so the pressure of the fuel cell 8 is changed to the circulation path 10 and the circulation path. 11 is a negative pressure. In that case, the flow of gas in the fuel cell system changes as shown in FIG. 4 (period II in FIG. 2). Since the circulation path 10 and the circulation path 11 have internal volumes, during the period II, the gas stored in the circulation path 10 and the circulation path 11 is changed to the circulation path 10 → the gas-liquid separator 4 → the circulation path 11. → Second check valve 3 → Fuel cell inlet 6 → Fuel cell 8 At this time, if the gas consumption in the fuel cell 8 is constant, the flow rate of the gas flowing through the second check valve 3 is constant. Since the pressure at the fuel cell outlet 12 is lower than the pressure in the circulation path 10 by the pressure loss of the gas-liquid separator 4, the second check valve 3, the fuel cell 8 and the piping, the first check valve 2 is closed. It becomes a state. As a result, gas does not flow through the first check valve 2. Then, since the gas supply via the pressure regulator 1 is stopped, the pressure of the fuel cell 8 decreases, and when the fuel cell pressure detected by the pressure sensor 5 reaches a preset lower limit pressure, the control is performed. The device 9 resumes the output of the control signal. The control signal output at the time of restart is set so that the pressure of the gas passing through the pressure regulator 1 corresponds to the lower limit pressure, thereby preventing an excessive gas flow.

  The gas stored in the circulation path 10 and the circulation path 11 in the period I corresponds to the gas exhausted from the fuel cell 8, and the gas is supplied again to the fuel cell in the period II. Gas is circulated through. As can be seen from FIGS. 3 and 4, the gas flow is one-way, and water contained in the circulated gas is removed by the gas-liquid separator 4.

  There is a correlation between the rising / lowering speed of the fuel cell pressure, the gas flow rate flowing through the check valve, and the internal volume of the circulation path (assuming that the internal volume of the fuel cell inlet 6 and the fuel cell outlet 12 is sufficiently small). Specifically, in the period I, when the gas consumption amount of the fuel cell 8 is constant, the faster the increase rate of the fuel cell pressure is, and the larger the internal volume of the circulation path 10 and the circulation path 11 is, The gas flow rate of the first check valve 2 is increased. In the period II, the gas flow rate of the second check valve 3 is the same as the gas consumption of the fuel cell 8, and the larger the internal volume of the circulation path 10 and the circulation path 11, the higher the rate of decrease of the fuel cell pressure. Become slow.

  It is effective to increase the gas flow rate to remove the water that accumulates in the fuel cell, but in period I, the water is effectively removed by increasing the fuel cell pressure increase rate. I can do it. In the period II, since it is substantially equivalent to the dead end mode in which gas is not exhausted from the fuel cell outlet 12, water is not removed. That is, moisture removal in the fuel cell is performed only during period I.

  The length of the period I is determined by the gas consumption of the fuel cell 8, the internal volume of the circulation paths 10 and 11, and the rate of increase of the fuel cell pressure. When the upper and lower limit values are constant, the length of the period I can be adjusted by controlling the rate of increase of the fuel cell pressure. On the other hand, since the length of the period II is determined by the gas consumption of the fuel cell 8 and the internal volumes of the circulation paths 10 and 11, it cannot be positively controlled. Therefore, when it is necessary to adjust the duty ratio between the period I and the period II, the rate of increase in the fuel cell pressure during the period I is controlled. It is also possible to control the period I and period II by adjusting the range of the upper and lower limits of the fuel cell pressure. These controls are performed by the control device 9. That is, the control device 9 changes the control signal output to the pressure regulator 1 based on the fuel cell pressure detected by the pressure sensor 5.

  The operation in period II has been described with respect to the case where the output of the control signal from the control device 9 is completely stopped. However, the operation is also possible when the output of the control signal from the control device 9 is decreased with time. . FIG. 5 shows the control signal for the pressure regulator 1, the fuel cell pressure, and the pressure regulator 1 output from the control device 9 when the control signal from the control device 9 is linearly lowered in the period II. Gas flow (pressure regulator flow), gas flow through the first check valve 2 (first check valve flow), gas flow through the second check valve 3 (second check valve) The change over time of the valve flow rate is shown. In addition, FIG. 6 shows how the gas flows in the period II at this time. The gas flow through the circulation paths 10 and 11 is the same as in FIG. 4 except that the gas supply through the pressure regulator 1 is continued. The fuel cell pressure is supplied by the control device 9 and the pressure regulator 1 so that the pressure decreases at an arbitrary speed (gradient). At this time, the amount of gas supplied via the pressure regulator 1 is smaller than the amount of gas consumed by the fuel cell 8, and the fuel cell consumes the gas stored in the circulation path 10 and the circulation path 11, thereby Will decline. However, the gradient of the pressure drop is gentle as shown in FIG. 5 because the gas supply via the pressure regulator 1 exists compared to the case of FIG. When the pressure decreases and the fuel cell pressure detected by the pressure sensor 5 reaches a preset lower limit pressure, the control device 9 operates to increase the output of the control signal and shifts to the period I.

  In a certain amount of power generation (gas consumption), the slower the flow rate (gradient) of the pressure drop in period II, the more the flow rate through the pressure regulator 1 increases and the faster the pressure drop rate (gradient). The more steep it is, the smaller the flow rate through the pressure regulator 1 is. The maximum value of the pressure decrease rate is determined by the amount of gas consumed by the fuel cell, that is, the pressure decrease rate is not more than a certain value for a certain amount of power generation. FIG. 7 shows an operation waveform when control is performed so that the control signal is rapidly lowered at a pressure drop rate of a certain level or higher in the period II. The pressure regulator 1 receives a signal from the control device 9 so that the pressure rapidly decreases, and operates to reduce the flow rate. Since the control signal received from the control device 9 is more sudden than the pressure drop gradient due to gas consumption of the fuel cell, the pressure regulator 1 completely shuts off the gas supply. As a result, the rate of pressure reduction of the fuel cell is determined only by gas consumption (similar to the case of FIG. 3). The gas flow in this case is the same as in FIG. When the pressure decreases and the fuel cell pressure detected by the pressure sensor 5 reaches a preset lower limit pressure, the control device 9 operates to increase the output of the control signal and shifts to the period I. To do.

  As the waveform of the control signal when the control signal is lowered at a certain speed or higher in the period II as described with reference to FIG. 7, there are two types as shown in FIGS. In these figures, for simplicity, the scale is adjusted so that the fuel cell pressure and the control signal correspond to each other, and the same graph is drawn. FIG. 8 is a control in which the control signal is discontinuous when transitioning from the period II to the period I, so that the control signal is always increased from an arbitrary initial value during the period I ( Same as FIG. On the other hand, in FIG. 9, the control signal is controlled so as to constantly change. In this case, there is a period III in which the fuel cell pressure decreases despite an increase in the control signal. This is because the control signal output from the control device 9 is lower than the fuel cell pressure. As a result, the pressure regulator 1 is closed, and the fuel cell 8 consumes the gas stored in the circulation paths 10 and 11. The pressure continues to drop by continuing. Then, when the control signal exceeds the pressure of the fuel cell, the gas supply via the pressure regulator is resumed, and the period I is shifted to.

  As described above, for the sake of simplicity, the control signal has been described as being linearly increased in the period I, but the fuel cell system of the present invention can be operated even when control that is not linearly increased is performed. However, in that case, the flow rate of the first check valve 2 in the period I is not constant.

  In FIGS. 5 and 6, the control signal is described as being linearly decreased in the period II. However, the fuel cell system of the present invention can be operated even when control that is not linearly decreased is performed. However, in that case, the pressure regulator flow rate and the flow rate of the second check valve 3 in the period II are not constant.

  In the present embodiment, the hydrogen electrode side of the fuel cell has been described. However, the oxygen electrode side to which an oxidant such as air or oxygen is supplied is configured and operated according to the same principle. Is possible.

  In the above embodiment, a configuration example of so-called feedback control in which the control device 9 changes the control signal output to the pressure regulator 1 based on the fuel cell pressure detected by the pressure sensor 5 has been described. However, the characteristics of the fuel cell system may be evaluated in advance, the waveform and timing of the control signal may be set based on the characteristics, and the control signal output to the pressure regulator 1 may be changed. In this case, the pressure sensor 5 becomes unnecessary.

  Therefore, according to the fuel cell system of the present embodiment, the gas can be circulated without using a pump or an ejector, so that a highly efficient and simple fuel cell system can be constructed. In addition, since no pump or ejector is used, it is quiet and vibration free. In addition, since no moving parts are required (except for the pressure regulator), the reliability is high. In addition, it consumes less power and can maximize the power generated by the fuel cell (high energy efficiency).

  Although the invention made by the present inventor has been specifically described based on the embodiment, the invention is not limited to the embodiment and can be variously modified without departing from the scope of the invention. Needless to say.

  INDUSTRIAL APPLICABILITY The present invention is applicable to a fuel cell system that needs to circulate a gas, such as a mobile fuel cell system and a stationary fuel cell system.

  DESCRIPTION OF SYMBOLS 1 ... Pressure regulator, 2 ... 1st check valve, 3 ... 2nd check valve, 4 ... Gas-liquid separator, 5 ... Pressure sensor, 6 ... Fuel cell inlet, 7 ... Hydrogen cylinder, 8 ... Fuel cell, 9 ... Control device, 10, 11 ... Circulation path, 12 ... Fuel cell outlet.

Claims (9)

A fuel cell that is supplied with fuel and oxidant to generate electricity;
A pressure regulator capable of arbitrarily controlling the pressure of the fuel supplied to the fuel cell;
A first check valve connected to the outlet of the fuel cell;
A second check valve connected to the inlet of the fuel cell;
A circulation path provided between the first check valve and the second check valve;
The pressure of the fuel supplied to the fuel cell is increased by the pressure regulator, the fuel discharged from the fuel cell is stored in the circulation path via the first check valve, and is supplied to the fuel cell. The supply of the fuel is stopped or reduced by the pressure regulator, and the fuel stored in the circulation path is circulated to the fuel cell via the second check valve. Fuel cell system. The fuel cell system according to claim 1, wherein
A second pressure regulator capable of arbitrarily controlling the pressure of the oxidant supplied to the fuel cell;
A third check valve connected to the second outlet of the fuel cell;
A fourth check valve connected to the second inlet of the fuel cell;
A second circulation path provided between the third check valve and the fourth check valve;
The pressure of the oxidant supplied to the fuel cell is raised by the second pressure regulator, and the oxidant discharged from the fuel cell is stored in the second circulation path via the third check valve. The supply of the oxidant to the fuel cell is stopped or reduced by the second pressure regulator, and the oxidant stored in the second circulation path is circulated to the fuel cell via the fourth check valve. It is comprised so that it may make it. The fuel cell system characterized by the above-mentioned. The fuel cell system according to claim 1 or 2,
A pressure sensor for detecting the pressure at the inlet of the fuel cell;
A control device for controlling the pressure regulator based on a detection result of the pressure sensor,
The control device increases the pressure of the fuel supplied to the fuel cell by the pressure regulator, and stores the fuel discharged from the fuel cell in the circulation path via the first check valve, The supply of the fuel to the fuel cell is stopped or reduced by the pressure regulator and functions to circulate the fuel stored in the circulation path to the fuel cell via the second check valve. A fuel cell system. The fuel cell system according to claim 1 or 2,
A pressure sensor for detecting the pressure at the inlet of the fuel cell;
A control device for controlling the pressure regulator based on a detection result of the pressure sensor,
The control device increases the pressure of the fuel supplied to the fuel cell by the pressure regulator, and when the pressure at the inlet of the fuel cell detected by the pressure sensor reaches an upper limit value, the fuel cell The supply of the fuel to the fuel cell is stopped or reduced by the pressure regulator, and the supply of the fuel to the fuel cell is stopped when the pressure at the inlet of the fuel cell detected by the pressure sensor reaches a lower limit value. A fuel cell system that functions to be restarted by a pressure regulator. The fuel cell system according to claim 2, wherein
A second pressure sensor for detecting the pressure at the second inlet of the fuel cell;
A second control device for controlling the second pressure regulator based on a detection result of the second pressure sensor;
The second controller raises the pressure of the oxidant supplied to the fuel cell by the second pressure regulator, and causes the oxidant discharged from the fuel cell to pass through the third check valve. The second check valve stores the oxidant stored in the second circulation path, the supply of the oxidant to the fuel cell is stopped or reduced by the second pressure regulator, and the fourth check valve stores the oxidant stored in the second circulation path. A fuel cell system, wherein the fuel cell system functions to circulate through the fuel cell. The fuel cell system according to claim 2, wherein
A second pressure sensor for detecting the pressure at the second inlet of the fuel cell;
A second control device for controlling the second pressure regulator based on a detection result of the second pressure sensor;
The second controller raises the pressure of the oxidant supplied to the fuel cell by the second pressure regulator, and the pressure at the second inlet of the fuel cell detected by the second pressure sensor is an upper limit. When the value is reached, the supply of the oxidant to the fuel cell is stopped or reduced by the second pressure regulator, and the pressure at the second inlet of the fuel cell detected by the second pressure sensor is a lower limit value. The fuel cell system functions so that the supply of the oxidant to the fuel cell is resumed by the second pressure regulator when the pressure reaches the fuel cell. A fuel cell that is supplied with fuel and oxidant to generate electricity;
A pressure regulator capable of arbitrarily controlling the pressure of the oxidant supplied to the fuel cell;
A first check valve connected to the outlet of the fuel cell;
A second check valve connected to the inlet of the fuel cell;
A circulation path provided between the first check valve and the second check valve;
The pressure of the oxidant supplied to the fuel cell is raised by the pressure regulator, and the oxidant discharged from the fuel cell is stored in the circulation path via the first check valve, and the fuel cell The supply of the oxidant to the fuel cell is stopped or reduced by the pressure regulator, and the oxidant stored in the circulation path is circulated to the fuel cell via the second check valve. A fuel cell system. The fuel cell system according to claim 7, wherein
A pressure sensor for detecting the pressure at the inlet of the fuel cell;
A control device for controlling the pressure regulator based on a detection result of the pressure sensor,
The control device increases the pressure of the oxidant supplied to the fuel cell by the pressure regulator, and stores the oxidant discharged from the fuel cell in the circulation path via the first check valve. The supply of the oxidant to the fuel cell is stopped or reduced by the pressure regulator, and the oxidant stored in the circulation path is circulated to the fuel cell via the second check valve. A fuel cell system characterized by functioning. The fuel cell system according to claim 7, wherein
A pressure sensor for detecting the pressure at the inlet of the fuel cell;
A control device for controlling the pressure regulator based on a detection result of the pressure sensor,
The controller raises the pressure of the oxidant supplied to the fuel cell by the pressure regulator, and when the pressure at the inlet of the fuel cell detected by the pressure sensor reaches an upper limit value, the fuel The supply of the oxidant to the battery is stopped or reduced by the pressure regulator, and when the pressure at the inlet of the fuel cell detected by the pressure sensor reaches a lower limit value, the supply of the oxidant to the fuel cell A fuel cell system which functions to restart supply by the pressure regulator.

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