JP2002373682A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure interpolar differential pressure control, in a solid polymer electrolyte membrane fuel cell. SOLUTION: This fuel cell system comprises the fuel cell 1, having an anode electrode and a cathode electrode on the opposite sides of a solid polymer electrolyte membrane to generate power, when gaseous hydrogen is supplied to the anode electrode and air is supplied to the cathode electrode, a regulator 5 for reducing the pressure of the gaseous hydrogen supplied to the fuel cell 1 according to the pressure of the air, and a purge valve 8, disposed in a hydrogen off-gas recovery line 11 as a passage of gaseous hydrogen discharged from the fuel cell 1 and adapted to open, according to a differential pressure between both electrodes to release the pressure of hydrogen off-gas; and further comprises, on downstream side of the regulator 5, an interpolar differential pressure control valve 20 for controlling the differential pressure between both electrodes by releasing the gaseous hydrogen via valve travel control, according to thrust difference caused, when a first thrust based on the pressure of the air and urging force of a bias setting spring and a second thrust, based on the pressure of the gaseous hydrogen are brought in opposed action.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for controlling a pressure difference between electrodes in a solid polymer electrolyte membrane fuel cell.

[0002]

2. Description of the Related Art A fuel cell mounted on a fuel cell vehicle or the like is provided with an anode electrode and a cathode electrode on both sides of a solid polymer electrolyte membrane, and a fuel gas (for example, hydrogen gas) is supplied to the anode electrode. There is an electrode in which an oxidizing gas (for example, oxygen or air) is supplied to an electrode, and chemical energy involved in a redox reaction of the gas is directly extracted as electric energy. In this fuel cell, hydrogen gas is ionized on the anode side and moves through the solid polymer electrolyte, and electrons move to the cathode side through an external load, reacting with oxygen to produce water, a series of electrochemical processes. Electric energy from the reaction can be extracted.

FIG. 5 shows an example of a conventional fuel cell system provided with this fuel cell. In this fuel cell system,
The air as the oxidizing gas is pressurized to a predetermined pressure by the compressor 52, humidified by the cathode humidifier 53, and supplied to the cathode electrode of the fuel cell 51. After this air is used for power generation, it is discharged from the fuel cell 1 as air off-gas,
It is discharged via the pressure control valve 54. This pressure control valve 5
4 controls the supply pressure of air at the cathode electrode. on the other hand,
Hydrogen gas as a fuel gas is depressurized by the regulator 55, humidified by the anode humidifier 57 via the ejector 56, and supplied to the anode electrode of the fuel cell 1. here,
The regulator 55 reduces the pressure of the hydrogen gas supplied to the anode electrode according to the pressure of the air supplied to the cathode electrode. After being supplied to the power generation, the hydrogen gas is discharged as hydrogen off-gas from the fuel cell 1, is sucked into the ejector through the hydrogen off-gas recovery path 61, merges with the fresh hydrogen gas that has passed through the regulator, and is again supplied to the fuel cell 1. It is supplied to the anode electrode.

In this fuel cell system, in order to avoid breakage of the solid polymer electrolyte membrane, the pressure difference between the hydrogen gas pressure at the anode electrode and the air pressure at the cathode electrode is suppressed to a predetermined value or less. Need to drive. Therefore, conventionally, an electromagnetically driven purge valve 58 is provided in the hydrogen off-gas recovery passage 61, and the purge valve 58 is electrically controlled so as to open the purge valve 58 when the differential pressure reaches the specified value. Was. Japanese Patent Laid-Open No. 7-78624 discloses a similar technique. The purge valve 5
Reference numeral 8 denotes a valve which is not only opened for controlling the differential pressure but also opened as required when draining condensed water generated by condensing water contained in the hydrogen off-gas. It is.

[0005]

However, when the pressure difference between the two electrodes is controlled by electrically controlling the opening and closing of the purge valve 58 as in the prior art, the breakage of the electric signal line and the decrease in the electric power may cause a problem. Alternatively, if a failure occurs on the computer, the purge valve 58 may not operate, or unnecessary opening may be performed, thereby lowering system efficiency.

It is also conceivable that the excessive pressure is mechanically released by the maximum pressure management using a spring-type pop-off valve instead of the gap pressure management using the purge valve. Here, the spring-loaded pop-off valve has a spring load set in advance so as to open at the maximum specified pressure value, and when the pressure exceeds the specified value, the valve body that has been held closed by the spring load is opened. This is a mechanical relief valve having a structure for releasing pressure by valve. In this spring-type pop-off valve, the maximum specified pressure, which is the valve opening threshold, can be set to only one pressure value (constant pressure).

However, in the case of a fuel cell, FIG.
As shown in (2), the upper limit pressure of the anode electrode changes according to the output value of the fuel cell. Therefore, it is difficult and practically impossible to control the maximum pressure of the anode electrode of the fuel cell with a spring-type pop-off valve that can set only one point of the valve opening threshold (maximum specified pressure value). Thus, the present invention can reliably manage the gap pressure between electrodes even if the upper limit pressure of the reaction gas changes according to the output value of the fuel cell, and more reliably prevents breakage of the solid polymer electrolyte membrane. It is intended to provide a fuel cell system which can be used.

[0008]

In order to solve the above-mentioned problems, the invention described in claim 1 has an anode electrode and a cathode electrode on both sides of a solid polymer electrolyte membrane, and a fuel gas (for example, A fuel cell (for example, a fuel cell 1 according to an embodiment described later) is supplied with an oxidant gas (eg, air according to an embodiment described later) and a oxidant gas (eg, air according to an embodiment described below) is supplied to a cathode electrode. ), And the pressure of one of the fuel gas and the oxidant gas (for example, hydrogen gas in the embodiment described later) supplied to the fuel cell is increased by the other gas (for example, in the embodiment described later). A regulator (for example, a regulator 5 in an embodiment described later) that decreases in accordance with the pressure of the air) and the one of the ones discharged from the fuel cell. The flow path of the scan of the off-gas (e.g.,
Hydrogen off-gas recovery path 11 in an embodiment described later)
A purge valve (e.g., a purge valve 8 in an embodiment described later) that opens in response to the pressure difference between the two electrodes and releases the pressure of the off-gas. And a second thrust based on the pressure of the one gas and the first thrust based on the urging force of the elastic body (for example, a bias setting spring 29 in an embodiment described later). An inter-pole differential pressure adjusting valve that adjusts the valve opening degree in accordance with the thrust difference generated when the pressure is released to release the one gas and adjust the differential pressure between the two electrodes (for example, the inter-pole differential pressure adjusting valve in an embodiment described later) A pressure regulating valve 20) is provided downstream of the regulator.

With this configuration, even if the pressure of the fuel gas supplied to the anode electrode or the pressure of the oxidizing gas supplied to the cathode electrode changes in accordance with the output of the fuel cell, the voltage between the two electrodes is reduced. The differential pressure (hereinafter referred to as the interelectrode differential pressure) can be controlled by one or both of the purge valve and the interelectrode differential pressure adjusting valve. In particular, in the gap pressure regulating valve, the larger the pressure difference between the pressure of the one gas and the pressure of the other gas, the larger the thrust difference, and the larger the gap pressure difference valve, the larger the thrust difference. The inter-pole differential pressure is reduced by adjusting the valve opening to increase, and the inter-pole differential pressure is increased by adjusting the valve opening to decrease as the thrust difference decreases. As a result, the gap differential pressure regulating valve can adjust the gap differential pressure to a predetermined range. Further, since the operation of the gap differential pressure regulating valve is purely mechanical, it operates normally even when an electrical trouble occurs in the system.

According to a second aspect of the present invention, in the first aspect of the present invention, the differential pressure between the two electrodes, which is the valve opening threshold value of the purge valve, is the same as the valve opening threshold value of the differential pressure regulating valve. It is characterized in that it is set smaller than the pressure difference between the electrodes. With this configuration, the control of the gap pressure during normal operation is performed by the operation of the purge valve having a small valve opening threshold, and the gap pressure between the gaps is greater than the opening threshold of the gap pressure regulating valve. , Both the purge valve and the inter-pole differential pressure adjusting valve are opened to reduce the inter-pole differential pressure more quickly. Also, even in the event that the purge valve malfunctions, the gap pressure regulating valve operates to prevent breakage of the solid polymer electrolyte membrane.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the purge valve and the inter-pole differential pressure regulating valve are integrally formed, and one valve body (for example, The valve element 27) in the embodiment described later shares the valve element of the purge valve and the valve element of the inter-pole differential pressure regulating valve, and this valve element is provided with an electric signal as a drive timing. The partition can be opened and closed by a drive unit (for example, a plunger 35 and a solenoid coil 37 in an embodiment to be described later), and is a partition wall linked to the valve body. A partition (for example, a pressure regulating diaphragm 22 in an embodiment to be described later) on which a thrust acts in opposition is capable of adjusting a valve opening as a drive unit of the inter-pole differential pressure adjusting valve.
With this configuration, it is possible to reduce the number of components and the installation space.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fuel cell system according to the present invention will be described below with reference to FIGS. The fuel cell system according to each of the following embodiments is an embodiment mounted on a fuel cell vehicle.

[First Embodiment] First, a first embodiment of a fuel cell system according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of a fuel cell system. The fuel cell 1 is configured by stacking a large number of cells in which an anode electrode and a cathode electrode are provided on both sides of a solid polymer electrolyte membrane and a gas passage for supplying a reaction gas is provided outside each electrode. . The fuel cell 1 generates power by supplying hydrogen gas as a fuel gas to an anode electrode and air as an oxidant gas to a cathode electrode.

The air is pressurized by an air compressor 2, humidified by a cathode humidifier 3 and supplied to the cathode electrode of the fuel cell 1. After oxygen in the air is provided as an oxidant, the air is supplied from the fuel cell 1 to the air. It is discharged as off-gas and released to the atmosphere via the pressure control valve 4. ECU1
0 controls the pressure control valve 4 while driving the air compressor 2 to supply a predetermined amount of air to the fuel cell 1 according to the output required for the fuel cell 1 (hereinafter, required output). The supply pressure of air at the cathode electrode is adjusted to a pressure according to the required output of the fuel cell 1.

On the other hand, hydrogen gas released from a high-pressure hydrogen tank (not shown) is
After passing through the ejector 6, it is humidified by the anode humidifier 7 and supplied to the anode electrode of the fuel cell 1. After being supplied to the power generation, this hydrogen gas is discharged from the fuel cell 1 as hydrogen off-gas, sucked into the ejector 6 through the hydrogen off-gas recovery path 11, merged with the hydrogen gas supplied from the high-pressure hydrogen tank, and re-fueled. It is supplied to the battery 1 and circulates.

The regulator 5 is composed of, for example, a pneumatic proportional pressure control valve. The pressure of the air supplied from the air compressor 2 is input as a signal pressure through the air signal introduction path 15 and the pressure of the hydrogen gas at the outlet of the regulator 5 is controlled. The pressure is reduced so that the pressure falls within a predetermined pressure range corresponding to the signal pressure. In the fuel cell system according to this embodiment, the regulator 5 controls the pressure of the hydrogen gas supplied to the anode electrode (hereinafter referred to as “anode gas pressure”) to the pressure of the air supplied to the cathode electrode (hereinafter referred to as “anode electrode gas pressure”). , "Cathode electrode gas pressure").

The hydrogen off-gas recovery path 11 is connected to a hydrogen off-gas discharge path 12 via an electromagnetically driven purge valve 8. The ECU 10 operates the electromagnetic drive unit of the purge valve 8 to perform opening / closing control based on the differential pressure between the anode electrode gas pressure and the cathode electrode gas pressure, that is, the output of the differential pressure sensor 9 that detects the interelectrode differential pressure. . That is, the electromagnetic driver of the purge valve 8 uses the electric signal as the drive timing. The purge valve 8 is opened when the output value of the differential pressure sensor 9 reaches ΔP1 to control the gap differential pressure to be equal to or less than ΔP1, and opens when a predetermined condition is satisfied. There is an operation of draining water so that water does not accumulate on the anode electrode side of the fuel cell 1.

A hydrogen supply path 13 connecting the ejector 6 and the anode humidifier 7 is connected to a hydrogen off-gas discharge path via a hydrogen gas discharge path 14 provided with an inter-pole differential pressure regulating valve 20 having a characteristic configuration of the present invention. 12 is connected. This inter-pole differential pressure regulating valve 20 will be described with reference to the schematic sectional view of FIG. The internal space of the body 21 of the inter-pole differential pressure regulating valve 20 is vertically divided by a pressure regulating diaphragm 22, the space above the diaphragm 22 is a signal pressure chamber 23, and the lower space is hydrogen gas. It is a passage 24. The signal pressure chamber 23 is a closed space having an air introduction hole 25, and air pressurized by the compressor 2 is introduced into the signal pressure chamber 23 from the air introduction hole 25 via the air signal introduction path 15.

A stem 26 is attached to the lower surface of the diaphragm 22.
A valve body 27 that can be seated and separated from an upper side with respect to a valve seat portion 28 in 4 is provided. And the signal pressure chamber 23
Is provided with a bias setting spring (elastic body) 29 for urging the valve body 27 in a direction of sitting on the valve seat portion 28.

The body 21 communicates with a hydrogen gas inlet 31 communicating with the hydrogen gas passage 24a on the side where the valve body 27 is arranged, and with a hydrogen gas passage 24b on the side where the valve body 27 is not arranged. A hydrogen gas outlet 32 is provided. The hydrogen gas inlet 31 is connected to the hydrogen supply pipe 13 via the hydrogen gas discharge path 14, and the hydrogen gas outlet 32 is connected to the hydrogen off gas discharge path 12 via the hydrogen gas discharge path 14. It is connected. Therefore, as shown in FIGS. 1 and 2, when the hydrogen gas decompressed by the ejector 6 is introduced into the hydrogen gas passage 24 a from the hydrogen gas inlet 31, and the valve 27 is separated from the valve seat 28 and opened, Hydrogen gas passage 24a
Is introduced into the hydrogen gas passage 24b,
Further, the hydrogen gas flows from the hydrogen gas outlet 32 to the hydrogen off-gas discharge path 12.

It is preferable to use, of the components constituting the gap differential pressure regulating valve 20, components which are exposed to hydrogen gas and have excellent corrosion resistance to hydrogen. For example, the body 21, the valve body 27 and the stem 26 are preferably used. Is preferably made of stainless steel or aluminum subjected to surface alumite treatment, and the diaphragm 22 is preferably made of fluorine rubber.

The inter-pole differential pressure regulating valve 20 constructed as described above
Then, as a result of the air pressure in the signal pressure chamber 23 and the urging force of the spring 29 acting on the upper surface of the diaphragm 22, a first thrust based on these acts downward on the upper surface of the diaphragm 22, while the hydrogen gas passage As a result of the pressure of the hydrogen gas in 24 a acting on the lower surface of the diaphragm 22, a second thrust based thereon acts upward on the lower surface of the diaphragm 22. The diaphragm 22 moves by being governed by the difference between the first thrust and the second thrust.
That is, when the second thrust is smaller than the first thrust, a downward force acts on the diaphragm 22 and pushes the valve body 27 in a direction of approaching the valve seat portion 28 (that is, the valve closing direction). When the second thrust is greater than the first thrust, an upward force acts on the diaphragm 22 to push the valve body 27 away from the valve seat 28 (ie, in the valve opening direction).

The pressure of the air supplied to the signal pressure chamber 23 is substantially the same as the cathode gas pressure, and the pressure of the hydrogen gas supplied to the hydrogen gas passage 24a is substantially the same as the anode gas pressure. is there. Therefore, the gap differential pressure regulating valve 2
0 corresponds to a thrust difference generated when a first thrust based on the cathode electrode gas pressure and the urging force of the spring 29 and a second thrust based on the anode electrode gas pressure are applied to face each other with the diaphragm 22 interposed therebetween. Thus, it can be said that the valve is an adjustment valve for adjusting the valve opening.

In the gap differential pressure regulating valve 10 of this embodiment, the spring 29 is set to be compressed in the closed state (in other words, the urging force of the spring 29 is reduced in the closed state). It is set so as to act on the diaphragm 22) and the spring 29 in the valve closed state.
Is set to the upper limit value Plim of the gap differential pressure. With this setting, when the gap pressure is equal to or less than Plim, the first thrust is larger than the second thrust. Therefore, the valve body 27 maintains the closed state in which the valve body 27 is seated on the valve seat portion 28, When the pressure difference exceeds the upper limit value Plim, the second thrust is larger than the first thrust. Therefore, the valve body 27 is separated from the valve seat 28 and opens, and the hydrogen in the hydrogen gas passage 24a is opened. The gas escapes to the hydrogen off-gas discharge path 12 and acts to reduce the pressure difference between the electrodes. And
The valve body 27 moves in the valve closing direction with the decrease in the gap pressure, and when the gap pressure becomes equal to or less than the upper limit value Plim, the valve body 27 is seated on the valve seat portion 28 to close the valve. In the closed state, the biasing force F of the spring 29 and the upper limit value Pli of the gap pressure
The following equation holds between m and the area S of the diaphragm 22. F = Plim · S

In this embodiment, the differential pressure value ΔP1 which is the valve opening threshold value of the purge valve 8 is set smaller than the upper limit value Plim which is the valve opening threshold value of the gap differential pressure regulating valve 20. In this way, during normal operation, the gap differential pressure is managed by the purge valve 8 having a small valve opening threshold, and the fuel cell 1 can be maintained in a good operation state. Then, when the inter-electrode differential pressure becomes larger than the opening threshold value of the inter-electrode differential pressure control valve 20, both the inter-electrode differential pressure control valve 20 in addition to the purge valve 8 are opened to reduce the inter-electrode differential pressure. It can be quickly lowered to reliably prevent breakage of the solid polymer electrolyte membrane.

Further, since the gap differential pressure regulating valve 20 is operated purely mechanically, any electrical troubles in the system (for example, breakage of the electric signal line to the purge valve 8 or a decrease in power, or a computer) Even if the purge valve 8 malfunctions due to a trouble or the like, the gap differential pressure regulating valve 20 operates reliably to prevent breakage of the solid polymer electrolyte membrane, and is extremely excellent in fail-safe point. . The pressure management in this fuel cell system is performed by setting the valve opening threshold to 1
Instead of using a spring-type pop-off valve that can only set a point to control the maximum pressure of the anode electrode gas pressure, the inter-pole differential pressure is controlled by one or both of the purge valve 8 and the inter-pole differential pressure adjustment valve 20. Therefore, even if the anode gas pressure or the cathode gas pressure changes according to the output of the fuel cell 1, there is almost no effect on the control of the pressure difference between the electrodes. It can be prevented reliably.

FIG. 3 shows a modification in which the installation position of the gap differential pressure regulating valve 20 is changed. That is, in the example of FIG. 3, the inter-electrode differential pressure regulating valve 20 is provided in the hydrogen off-gas discharge path 16 connecting the hydrogen off-gas recovery path 11 and the hydrogen off-gas discharge path 12. Then, the hydrogen off-gas flowing through the hydrogen off-gas recovery passage 11 passes through the hydrogen off-gas passage 16 from the hydrogen gas inlet 31 of the inter-pole differential pressure regulating valve 20 in FIG.
Will be introduced. Further, the air pressurized by the compressor 2 is introduced into the signal pressure chamber 23 from the air introduction hole 25 via the air signal introduction passage 17. With the inter-pole differential pressure regulating valve 20 installed in this way, the inter-pole differential pressure regulating valve 20 can be opened and reduced in the case where the inter-pole differential pressure exceeds Plim. The same operation and effect as those of the first embodiment can be obtained.

[Second Embodiment] FIG. 4 shows an example in which the purge valve 8 and the inter-electrode differential pressure regulating valve 20 are integrated. Note that, here, the whole integrated valve is referred to as an interelectrode differential pressure regulating valve 20 for convenience. Also in the case of the gap differential pressure regulating valve 20, the body 21 and the pressure regulating diaphragm (partition) 2
2, the signal pressure chamber 23, and the hydrogen gas passages 24, 24a, 2
4b, air introduction hole 25, stem 26, valve body 27
, A valve seat 28, a bias setting spring 29, a hydrogen gas inlet 31, and a hydrogen gas outlet 32. The valve element 27 is a valve element of the purge valve as well as a valve element of the inter-pole differential pressure adjusting valve, and thus shares the valve element 27. In the gap differential pressure regulating valve 20, the stem 2
6 also extends above the diaphragm 22 and the stem 2
A purge valve plunger (drive section for the purge valve) 35 is provided at the upper end of the plunger 6, and a plunger storage section 36 that stores the plunger 35 movably up and down is provided in the body 21. A solenoid coil (driving unit of a purge valve) 37 for moving the plunger 35 up and down is provided outside the.

When the inter-pole differential pressure adjusting valve 20 functions as the above-described purge valve 8, a current flows through the solenoid coil to form an electromagnet, and the plunger 35 is pulled upward against the urging force of the spring 29. Then, the valve body 27 is separated from the valve seat portion 28 to open the valve. That is, the valve element 27 as a purge valve is opened and closed by a drive unit (plunger 35, solenoid coil 37) that uses an electric signal as a drive timing.

The first thrust based on the pressure of the air in the signal pressure chamber 23 and the urging force of the spring 29 and the first thrust in the hydrogen gas passage 24a are provided in the partition wall 22 linked to the valve body 27 through the stem 26. The second thrust based on the pressure of the hydrogen gas acts in opposition, and the partition wall 22 functions as a drive unit for adjusting the valve opening of the valve body 27 (drive unit for the inter-electrode differential pressure adjustment valve). have. That is, when a normal operation as the purge valve is not performed due to some kind of electric trouble (for example, breakage of the electric signal line or a decrease in power), and the gap pressure exceeds the upper limit value Plim, Since the second thrust is larger than the first thrust, the valve body 27 is opened apart from the valve seat portion 28, and the hydrogen gas in the hydrogen gas passage 24a is removed from the hydrogen off-gas discharge passage 12a.
And acts to reduce the gap pressure.
Then, the valve element 27 moves in the valve closing direction with the decrease in the gap pressure, and when the gap pressure falls below the upper limit value Plim, the valve body 27 sits on the valve seat portion 28 and closes the valve.

As described above, by integrating the purge valve and the inter-pole differential pressure regulating valve, the number of components of the system can be reduced by one, and the space occupied by the system can be reduced. This is very advantageous in a fuel cell system for use.

[Other Embodiments] The present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, the inter-electrode pressure adjusting valve is used for the inter-electrode differential pressure adjustment in the fuel cell system in which the anode electrode gas pressure is controlled to be larger than the cathode electrode gas pressure. It is also possible to use the pole-to-pole pressure regulating valve 20 for regulating the pole-to-pole differential pressure in a fuel cell system that controls to be greater than the pole gas pressure.

[0033]

As described above, according to the first aspect of the present invention, the pressure of the fuel gas supplied to the anode electrode or the pressure of the oxidizing gas supplied to the cathode electrode changes the output of the fuel cell. Even if it changes accordingly, the gap pressure can be controlled by one or both of the purge valve and the gap pressure regulating valve, so that a good operating condition of the fuel cell can be ensured without reducing the system efficiency. And the solid polymer electrolyte membrane can be reliably prevented from being damaged. In particular, the gap differential pressure control valve adjusts the gap differential pressure to a desired range by purely mechanical operation, so that it operates normally even when an electrical trouble occurs in the system, and has a fail-safe point. But it is extremely good.

According to the second aspect of the invention, the control of the gap pressure during normal operation can be performed by operating the purge valve having a small valve opening threshold, and the gap pressure is reduced. When the pressure exceeds the opening threshold of the regulating valve, both the purge valve and the gap pressure regulating valve are opened to quickly reduce the gap pressure, so that the solid polymer electrolyte membrane is surely damaged. Can be prevented. Also, even in the event that the purge valve malfunctions, the gap differential pressure regulating valve operates to reliably prevent breakage of the solid polymer electrolyte membrane, and is therefore extremely excellent in terms of fail-safe. According to the third aspect of the invention, there is an effect that the number of parts and the installation space can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a fuel cell system according to a first embodiment of the present invention.

FIG. 2 is a sectional view of an inter-pole differential pressure regulating valve used in the first embodiment.

FIG. 3 is a schematic configuration diagram in a modified example of the first embodiment.

FIG. 4 is a sectional view of an inter-electrode differential pressure regulating valve in a fuel cell system according to a second embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing an example of a conventional fuel cell system.

FIG. 6 is a graph showing the relationship between the output of the fuel cell and the upper limit of the hydrogen pole.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fuel cell 5 Regulator 8 Purge valve 11 Hydrogen off-gas recovery path (off-gas flow path of one gas) 20 Pole difference pressure regulating valve 22 Pressure regulating diaphragm (partition wall) 27 Valve element 29 Bias setting spring (elastic body) 35 Plunger (drive section for purge valve) 37 Coil for solenoid (drive section for purge valve)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H026 AA06 5H027 AA06 KK02 KK05 KK12 MM01 MM02

Claims (3)

[Claims] 1. A fuel cell having an anode electrode and a cathode electrode on both sides of a solid polymer electrolyte membrane, wherein a fuel gas is supplied to the anode electrode and an oxidant gas is supplied to the cathode electrode to generate power, and the fuel cell A regulator for reducing the pressure of one of the supplied fuel gas and the oxidizing gas in accordance with the pressure of the other gas; and a regulator provided in a flow path of the off-gas of the one gas discharged from the fuel cell. A purge valve that opens in response to the pressure difference between the two electrodes to release the pressure of the off-gas, and a first thrust based on the pressure of the other gas and the urging force of an elastic body. The second thrust based on the pressure of the one gas and the thrust difference generated when the two thrusts are caused to act opposite to each other, the valve opening is adjusted according to the thrust difference, the one gas is released, and the gap between the two electrodes is released. Fuel cell system, characterized in that the inter-electrode differential pressure control valve for adjusting the pressure, provided downstream of the regulator. 2. A pressure difference between both electrodes, which is a valve opening threshold of said purge valve, is set smaller than a pressure difference between both electrodes which is a valve opening threshold of said differential pressure regulating valve. The fuel cell system according to claim 1, wherein: 3. The purge valve and the inter-pole differential pressure adjusting valve are integrally formed, and one valve body shares the valve body of the purge valve and the inter-pole differential pressure adjusting valve. The valve body can be opened and closed by a drive unit of the purge valve whose drive timing is an electric signal, and is a partition wall associated with the valve body, and the first thrust and the second thrust force are provided on both sides thereof. 3. The fuel cell system according to claim 1, wherein a partition wall on which thrust acts in opposition is capable of adjusting a valve opening as a drive unit of the inter-pole differential pressure regulating valve. 4.