JP2006134618A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system preventing leakage of fuel gas toward the oxidant electrode side by improving the sealing performance of a valve at normal operation. <P>SOLUTION: The fuel cell system 1 is provided with a fuel cell 2 generating power by the reaction of fuel gas and oxidant gas, a fuel gas flow passage 3 through which the fuel gas flows, an oxidant gas flow passage 4 through which the oxidant gas flows, a communication flow passage 5 for communicating the fuel gas passage 3 with the oxidant gas flow passage 4, and a communication blocking means (6) for blocking communication between the fuel gas flow passage 3 and the oxidant gas flow passage 4, when the fuel cell 2 generates power. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system that generates power by a reaction between a fuel gas and an oxidant gas.

  Conventionally, in a fuel cell system, a fuel gas (hydrogen) and an oxidant gas (air) containing hydrogen are respectively present at a fuel electrode (hydrogen electrode) and an oxidant electrode (air electrode) facing each other across a solid polymer film. Supplied. The fuel cell generates power by an electrochemical reaction between the fuel gas and the oxidant gas. Although this fuel cell stem generates water by power generation, the water may not be discharged and may accumulate in the fuel cell system. Further, when fuel gas is recirculated to improve fuel efficiency, the fuel gas and air permeate each other through the thin solid polymer film, and air accumulates in the recirculated fuel gas. If this happens, there is a risk that the fuel consumption and power generation performance will decrease, and the electrodes, the solid polymer film, etc. may deteriorate.

For this reason, in this fuel cell system, water accumulated in the system or residual gas is scavenged (discharged) with scavenging gas. Patent Document 1 describes that scavenging is performed by supplying air supplied from a compressor for an oxidant electrode as a scavenging gas to the fuel electrode when the system is stopped.
Japanese Patent Laying-Open No. 2003-331893 (paragraphs 0012 to 0019, FIG. 1)

  By the way, when the fuel electrode is scavenged by using the air supplied from the compressor on the oxidant electrode side as the scavenging gas by communicating the oxidant side and the fuel electrode side, the fuel gas and the air are separated during normal operation for the reasons described above. It is necessary to prevent mixing.

  Therefore, the present invention has been made to solve the problems of the prior art, and an object of the present invention is to improve the sealing performance of the valve body during normal operation and to improve the oxidizer electrode side of the fuel cell. It is an object of the present invention to provide a fuel cell system that prevents fuel gas from leaking.

  In order to solve the above-described problem, the fuel cell system according to claim 1 includes a fuel cell that generates power by a reaction between a fuel gas and an oxidant gas, a fuel gas flow passage through which the fuel gas flows, and the oxidation A fuel cell system comprising: an oxidant gas flow passage through which an oxidant gas circulates; and a communication passage communicating the fuel gas flow passage and the oxidant gas flow passage. A communication blocking means for blocking communication between the fuel gas flow path and the oxidant gas flow path is provided.

  According to the first aspect of the fuel cell system of the present invention, at the time of power generation of the fuel cell, the communication cut-off means cuts off the communication between the fuel gas flow path and the oxidant gas flow path, Is prevented from mixing. As a result, the fuel cell can prevent the electrode from coming into contact with the gas in which the fuel gas and the oxidant gas are mixed, and oxidizing and deteriorating. In addition, since the fuel cell system includes the communication cut-off means, the fuel gas is prevented from leaking, so that the consumption of the fuel gas can be suppressed.

  The fuel cell system according to claim 2 is the fuel cell system according to claim 1, wherein the communication blocking means is disposed on the communication path and includes a valve body that opens and closes a valve seat. The scavenging gas introduction valve comprises an introduction valve, the valve body is provided in communication with a high-pressure side flow passage having a high pressure among the fuel gas flow passage and the oxidant gas flow passage, and the valve seat is provided with It is provided in communication with a low pressure side flow passage having a lower pressure than the high pressure side flow passage.

  According to the fuel cell system of the present invention, when the fuel cell system is in operation, the pressure on the fuel electrode side applied to the valve body is larger than the pressure on the oxidant electrode side. For this reason, for example, by disposing the fuel electrode on the side where the valve body of the scavenging gas introduction valve is present, the pressure difference between the fuel electrode (high pressure side flow passage) and the oxidant electrode (low pressure side flow passage) The valve body works to press against the valve seat. Therefore, during operation of the fuel cell system, unless the valve body is forcibly opened, the valve body reliably closes the valve seat, so that the fuel gas and the oxidant gas are not mixed.

  The fuel cell system according to claim 3 is the fuel cell system according to claim 2, wherein an area of the valve body in contact with the high-pressure side flow passage is an area of an opening of the valve seat. It is characterized by being larger.

According to the invention of the fuel cell system according to claim 3, the area of the valve body contacting the high pressure side flow passage is larger than the area of the opening of the valve seat, so that the valve body is controlled by the pressure of the high pressure side flow passage. Since it is pressed against the valve seat, the valve body reliably closes the valve seat during power generation.
Thus, the fuel cell system can improve the sealing performance of the valve body without increasing the magnetic force of the solenoid, for example, by allowing the valve body to reliably close the valve seat without increasing the spring load of the valve spring. Can do.

  The fuel cell system according to claim 4 is the fuel cell system according to claim 1, wherein the communication blocking means prevents a back flow of gas from the fuel gas flow path side to the oxidant gas flow path side. It consists of a check valve.

  According to the invention of the fuel cell system according to claim 4, for example, in the case of a fuel cell system having a high pressure on the fuel electrode side, the fuel gas is oxidant gas with a simple configuration by providing a check valve. It is possible to prevent leakage to the side and to scavenge the fuel gas circulation system. Thereby, it is possible to prevent the generated water from being clogged in the fuel circulation passage of the fuel cell system and causing the flooding phenomenon.

  According to the fuel cell system of the present invention, at the time of power generation of the fuel cell, the communication cut-off means cuts off the communication between the fuel gas flow path and the oxidant gas flow path, and the fuel gas leaks to the oxidant gas side and is mixed. Can be prevented. As a result, the fuel cell can prevent the gas mixed with the fuel gas and the oxidant gas from flowing to the electrode and oxidize and deteriorate the electrode, and also prevent the fuel gas from leaking. Can be reduced.

Next, the best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described with reference to FIGS. 1 and 2.
FIG. 1 is a block diagram of a fuel cell system according to an embodiment of the present invention.

≪Fuel cell system≫
A fuel cell system 1 shown in FIG. 1 is used, for example, in a vehicle that travels with a fuel cell stack (hereinafter referred to as “fuel cell”) as a power source and a travel motor driven by the power of the fuel cell 2. The fuel cell system 1 includes a fuel cell 2 that generates power by a reaction between a supplied fuel gas and an oxidant gas, a fuel gas flow passage 3 through which the fuel gas flows, and an oxidant gas flow through which the oxidant gas flows. The communication path 5, the communication path 5 that connects the fuel gas flow path 3 and the oxidant gas flow path 4, and the communication between the fuel gas flow path 3 and the oxidant gas flow path 4 are shut off when the fuel cell 2 generates power. A scavenging gas introduction valve (communication cutoff means) 6 is provided.

≪Fuel cell≫
The fuel cell 2 shown in FIG. 1 is configured, for example, by stacking a plurality of fuel cells each sandwiching a solid polymer electrolyte membrane with a fuel electrode 2a and an oxidant electrode 2b interposed between separators. . The fuel cell 2 generates electric power by, for example, an electrochemical reaction between oxygen in the air as the oxidant gas supplied to the oxidant electrode 2b and hydrogen as the fuel gas supplied to the fuel electrode 2a. It is structured. When processing this hydrogen and oxygen, the fuel cell 2 generates electric power and heat.
The fuel electrode 2a is connected to the ejector 7 on the fuel gas supply port side to which one fuel gas (hydrogen) is supplied, and connected to the catch tank 8 on the other fuel gas discharge side. The oxidant electrode 2b has one oxidant gas supply port side connected to a compressor 14 constituting an air supply unit that supplies air as oxidant gas (oxygen), and the other oxidant gas discharge side connected to a back pressure valve 15. Has been.

≪Fuel gas flow path≫
The fuel gas flow passage 3 supplies a fuel gas such as hydrogen from the fuel gas supply unit 10 to the fuel gas supply port of the fuel electrode 2a, and discharges the fuel gas in the fuel electrode 2a from the fuel gas discharge port to the outside. It is a flow passage for making it. In the fuel gas flow passage 3, a fuel gas supply unit 10, a pressure control unit (not shown), and an ejector 7 are connected to the fuel gas supply port side of the fuel electrode 2a, respectively. A catch tank 8, a check valve 11 and a discharge valve 13 are connected via the fuel gas circulation passage 3b. The fuel gas flow passage 3 includes a fuel gas introduction passage 3a, a fuel gas circulation passage 3b, and a discharge passage 3c, which will be described later.

<Fuel gas introduction path>
The fuel gas introduction path 3 a is a pipe for sending fuel gas from the fuel gas supply unit 10 to the fuel electrode 2 a via the ejector 7.

<Fuel gas circulation passage>
The fuel gas circulation passage 3b is configured to catch the exhaust fuel gas discharged from the fuel gas discharge port of the fuel cell 2 during the normal operation of the fuel cell system 1 as shown in FIG. This is a pipe for circulating through the ejector 7 to the fuel gas supply port of the fuel cell 2 again. The fuel gas circulation passage 3b is connected in parallel to the fuel electrode 2a. One end of the fuel gas circulation passage 3b is connected to a joint portion a provided in the discharge passage 3c between the downstream portion of the catch tank 8 and the discharge valve 13, and the other end is connected to the ejector 7. Are provided with a joint b and a check valve 11 connected to the communication passage 5 described later. In addition, the joint parts a and b and the joint part c described later are T-shaped joints.

<Discharge passage>
The discharge passage 3c is a pipe for discharging the fuel gas and the oxidant gas (scavenging gas) supplied to the fuel electrode 2a through the fuel gas introduction passage 3a to the outside through the discharge valve 13.

≪Fuel gas supply part≫
The fuel gas supply unit 10 is composed of a gas cylinder and stores fuel gas supplied to the fuel electrode 2 a of the fuel cell 2.

≪Ejecta≫
The ejector 7 is composed of a nozzle part and a diffuser part (not shown), and the fuel gas supplied from the fuel gas supply part 10 via the pressure control part (not shown) is accelerated when passing through the nozzle part. It is injected toward the diffuser part. When the fuel gas flows from the nozzle portion toward the diffuser portion at a high speed, a negative pressure is generated in the side flow chamber provided between the nozzle portion and the diffuser portion, and the fuel electrode passes through the fuel gas circulation passage 3b. The exhaust fuel gas on the 2a side is sucked and mixed with the fuel gas. The fuel gas and the exhaust fuel gas mixed in the ejector 7 are sent to the fuel gas supply port of the fuel cell 2. Further, the discharged fuel gas discharged from the fuel cell 2 circulates through the fuel gas circulation passage 3 b via the ejector 7 and is supplied to the fuel cell 2 again.

≪Catch tank, drain valve≫
The catch tank 8 is a hollow box that separates excess water (mainly liquid water) in the fuel gas in the fuel gas flow passage 3 so that it can stay inside, and is a drain for discharging generated water. A valve 9 is installed.
The drain valve 9 can discharge the generated water retained in the catch tank 8 to the outside by opening the drain valve 9.

≪Check valve≫
The check valve 11 prevents the fuel gas and the scavenging gas flowing through the fuel gas circulation passage 3b from flowing in only one direction in the direction of arrow A in FIG. 1 (from the downstream side of the catch tank 8 toward the ejector 7). It is a valve for. As shown in FIG. 1, the check valve 11 is interposed between the joint part a and the joint part b in the fuel gas circulation passage 3b. The distance between the joint portions a and b is as short as possible.

≪Fuel gas discharge part≫
The fuel gas discharge part 12 is a part for discharging the exhaust fuel gas and the scavenging gas discharged from the fuel gas discharge port of the fuel electrode 2a to the outside. The fuel gas discharge part 12 adjusts the discharge of the fuel gas. A discharge valve 13 is provided. The fuel gas discharge section 12 is connected to the downstream side of the catch tank 8 in the fuel gas circulation passage 3b through a discharge valve 13.

≪Discharge valve≫
The discharge valve 13 is a valve whose opening / closing operation is controlled in accordance with the operating state of the fuel cell 2 and for discharging the fuel gas and scavenging gas (oxidant gas) containing impurities in the fuel gas circulation passage 3b to the outside. is there. The discharge valve 13 is disposed in the fuel gas flow passage 3 in a discharge passage 3 c provided outward from a joint portion a installed on the downstream side of the fuel cell 2.

≪Oxidant gas flow passage≫
The oxidant gas flow passage 4 supplies an oxidant gas such as air to the oxidant gas supply port of the oxidant electrode 2b, and discharges the oxidant gas in the oxidant electrode 2b from the oxidant gas discharge unit 16 to the outside. It is a flow passage for distribution. In the oxidant gas flow passage 4, a compressor 14, a heat radiating part and an oxidant humidification part are connected to the oxidant gas supply port side of the oxidant electrode 2b, and a back pressure valve 15 is connected to the oxidant gas discharge port side. Is connected. In the oxidant gas flow passage 4, a communication passage 5 described later is connected between the oxidant gas supply port of the fuel cell 2 and the compressor 14.

≪Compressor≫
The compressor 14 is a device for sending air as an oxidant gas into the oxidant gas flow path 4 and the communication path 5, and is installed on the upstream side of the oxidant gas flow path 4.

≪Oxidant gas discharge part, back pressure valve≫
The oxidant gas discharge unit 16 is a part for discharging the oxidant gas discharged from the oxidant gas discharge port of the fuel cell 2 to the outside. The oxidant gas discharge unit 16 adjusts the discharge of the oxidant gas. A back pressure valve 15 is installed.

≪Communication passage≫
The communication path 5 is a pipe for communicating the fuel gas flow path 3 and the oxidant gas flow path 4 to send the oxidant gas to the fuel gas circulation path 3b. One of the communication passages 5 is connected to a joint portion c disposed between the compressor 14 and the oxidant gas supply port of the oxidant electrode 2 b, and the other is disposed between the ejector 7 and the check valve 11. It is connected to the joint part b.

≪scavenging gas introduction valve≫
The scavenging gas introduction valve 6 shuts off the communication between the oxidant gas flow passage 4 and the fuel gas flow passage 3 during power generation of the fuel cell 2, and opens the valve element 69 (see FIG. 2) during scavenging. This is a valve for introducing the oxidant gas in the gas flow passage 4 into the fuel gas flow passage 3. During normal operation, the scavenging gas introduction valve 6 is connected to one of the fuel gas flow passage 3 and the oxidant gas flow passage 4 at a high pressure side flow passage and the other (introduction port side). Is connected to a low pressure side flow passage whose pressure is lower than that of the high pressure side flow passage. In the fuel cell system 1 of the present invention, the pressure on the fuel gas flow passage 3 side of the scavenging gas introduction valve 6 is higher than that on the oxidant gas flow passage 4 side. The scavenging gas introduction valve 6 corresponds to “communication blocking means” described in the claims.

FIG. 2 is a cross-sectional view showing an example of a scavenging gas introduction valve used in the fuel cell system according to the embodiment of the present invention.
Further, the scavenging gas introduction valve 6 will be described in detail with reference to FIG.
As shown in FIG. 2, the scavenging gas introduction valve 6 includes a valve body 61, a plunger 62, a guide member 63, a plate member 64, a cover member 65, a solenoid 66, a housing 67, and a valve seat 68. And a solenoid valve provided with a valve body 69.

  The valve body 61 is formed of a metal material, and an introduction port 61a into which an oxidant gas as a scavenging gas is introduced, a lead-out port 61b through which the scavenging gas is led out to the fuel gas flow passage 3, and a valve of the introduction port 61a And a drive space 61c disposed so that the valve element 69 for opening and closing the seat 68 can be driven.

The introduction port 61 a is a passage for sending oxidant gas (scavenging gas) to the drive space 61 c in the valve body 61, and communicates with the oxidant gas flow passage 4 via the communication passage 5. A valve seat 68 is screwed to the opening end of the introduction port 61a on the drive space 61c side.
The lead-out port 61b is a passage through which the oxidant gas in the introduction port 61a is released from the scavenging gas introduction valve 6 when the valve body 69 is separated from the valve seat 68, and communicates with the ejector 7 via the joint portion b. is doing.

  The drive space 61c is a space that is always in communication with the introduction port 61a, and is disposed between the introduction port 61a and the outlet port 61b so as to be orthogonal to each other. A valve element 69 is provided in the drive space 61c so as to be movable up and down in the axial direction. In addition to the valve element 69, a valve spring SP, a stopper 63a, and the valve seat 68 are provided in the drive space 61c. The drive space 61c is formed by the valve body 61 and the guide member 63, and a sealing member is interposed between the valve body 61 and the guide member 63 to maintain airtightness.

  The plunger 62 is made of a magnetic metal that is attracted by a magnetic force when electricity flows through the solenoid 66 and separates the valve body 69 installed at the lower end portion from the valve seat 68. One end of the plunger 62 is pressed against the upper surface of the valve body 69, and the other end is pressed against the guide member 63. When the solenoid 66 is OFF, a valve spring SP is pressed to press the valve body 69 against the valve seat 68. It is fitted. The plunger 62, the valve body 69, and the valve seat 68 are installed on the same axis.

  The guide member 63 is disposed at the upper part of the valve body 61, and a plunger 62 is provided therein so as to be movable back and forth along the axial direction, and the plunger 62 is movably supported together with the bobbin of the solenoid 66 and the plate member 64. is doing. The guide member 63 is provided with a stopper 63 a for suppressing the valve element 69 that is separated from the valve seat 68.

The plate member 64 is formed in an annular shape from a magnetic metal material, and is integrally connected between the guide member 63 and the solenoid 66. A through hole for movably inserting the plunger 62 is formed in the central portion of the plate member 64 along the axial direction.
The cover member 65 is disposed above the guide member 63 via a plate member 64, and a connector portion 65a for supplying a current to the coil of the solenoid 66 is provided on the outer peripheral portion.
The solenoid 66 includes a bobbin around which a coil is wound, and a plunger 62 that is movably provided in the bobbin, and is disposed inside the cover member 65.
The housing 67 is mounted so as to cover the outside of the cover member 65 and the solenoid 66 via a sealing material.

  The valve seat 68 is disposed below the valve element 69 in the driving space 61c, and is formed to protrude upward by a predetermined length from the lower surface of the driving space 61c. The end of is arranged.

FIG. 3 is a schematic diagram showing the relationship between the valve body and the valve seat of the scavenging gas introduction valve used in the fuel cell system according to the embodiment of the present invention.
As shown in FIG. 2, the valve body 69 is a member that opens and closes the valve seat 68, and cushioning materials 69a and 69b made of packing such as synthetic rubber are provided on the surface and the surface in contact with the valve seat 68 and the stopper 63a. It is installed in one. As shown in FIG. 3, the valve body 69 is formed such that the area S1 on the side in contact with the fuel gas in the fuel gas flow passage (high pressure side flow passage) 3 is larger than the area S2 of the opening of the valve seat 68. ing.

  The valve spring SP is a coil spring interposed between the upper surface of the valve body 69 and the guide member 63, and urges the valve body 69 in a direction in which the valve body 69 is pressed against the valve seat 68 by a spring force (elastic force F2). . The valve spring SP is supported by being loosely fitted into a cylindrical plunger 62 and loosely inserted into a cylindrical stopper 63a (see FIG. 2).

<< Operation >>
Next, the operation of the fuel cell system 1 will be described with reference to FIGS.
As shown in FIG. 1, the fuel cell 2 is supplied from the fuel gas supply unit 10 through the ejector 7 through the fuel gas flow passage 3 and from the compressor 14 through the oxidant gas flow passage 4. Electric power and heat are generated by an electrochemical reaction with the oxidant gas (oxygen).

  During steady operation of the fuel cell system 1, the scavenging gas introduction valve 6 and the exhaust valve 13 are closed by a control device (not shown). Therefore, as shown by a thick line in FIG. 1, the fuel gas sent from the ejector 7 to the fuel electrode 2a passes through the fuel gas circulation passage 3b via the catch tank 8, the check valve 11, and the ejector 7, It is circulated in the direction of arrow A so as to return to the fuel electrode 2a again. In this way, fuel gas consumption is reduced.

  The scavenging gas introduction valve 6 shown in FIG. 2 is in a non-excited state in which the solenoid 66 is turned off by a control device (not shown), so that the valve element 69 is moved by the elastic force F2 of the valve spring SP. It is closed because it is pressed against 68 and closed. The pressure P of the outlet port 61b is, for example, four times higher than the pressure Q of the inlet port 61a because the exhaust valve 13 is closed and the fuel gas is circulated through the fuel gas circulation passage 3b by the ejector 7. (See FIG. 1). The area S1 of the valve body 69 on the side in contact with the fuel gas in the fuel gas flow passage 3 is formed larger than the area S2 of the opening of the valve seat 68.

For example, the force that pushes the valve element 69 toward the plunger 62 by the pressure Q of the oxidizing gas (scavenging gas) in the introduction port 61a is f, and the valve element 69 causes the valve element 69 to be adjusted by the pressure P of the fuel gas in the outlet port 61b. The force pressing the valve seat 68 side is F1, the area of the valve body 69 on the side in contact with the fuel gas in the fuel gas flow passage 3 is S1 (see FIG. 3), and the area of the opening of the valve seat 68 is S2 (FIG. 3). See)
F1 = S1 × P
f = S2 × Q
It becomes. And
S1> S2
P> Q
Because
F1> f
It becomes. Further, since the elastic force F2 is biased to the valve spring SP in the same direction as the force F1, the valve body 69 is firmly attached with a strong force when the scavenging gas introduction valve 6 is OFF. The valve seat 68 is closed, and the inlet port 61a and the outlet port 61b are blocked.

  Then, when the power generation state of the fuel cell 2 shown in FIG. 1 is stopped and the pressure of the fuel gas in the fuel gas circulation passage 3b decreases, the exhaust valve 13 and the scavenging gas introduction valve are not controlled by a sensor and a control device (not shown). 6 is opened. Then, the fuel gas in the fuel gas circulation passage 3b is discharged from the discharge valve 13 to the outside through the discharge passage 3c and the discharge valve 13.

  The scavenging gas introduction valve 6 shown in FIG. 2 energizes the solenoid 66 from the control device, thereby exciting the coil, and the plunger 62 causes the valve element 69 to resist the elastic force F2 of the valve spring SP by the magnetic force of the coil. Move in a direction away from the valve seat 68. The valve body 69 comes to rest when the cushioning material 69 a abuts against the stopper 63 a of the guide member 63.

  As a result, the scavenging gas introduction valve 6 is switched from the off state to the on state (valve open state). Then, the oxidant gas (scavenging gas) from the compressor 14 shown in FIG. 1 flows into the drive space 61c from the introduction port 61a through the oxidant gas flow path 4 and the communication path 5, and from the outlet port 61b to the joint portion b. The ejected gas passes through the ejector 7, the fuel electrode 2 a, the catch tank 8, and the discharge valve 13, and is discharged to the outside from the fuel gas discharge unit 12.

  When the scavenging of the fuel gas is completed and the normal state of the power generation state by the fuel cell 2 is restored, the fuel gas is sent from the fuel gas supply unit 10 to the fuel electrode 2a via the ejector 7 by the control device, and the scavenging is performed. The gas introduction valve 6 and the discharge valve 13 are shut off. Then, the fuel gas discharged from the fuel electrode 2 a is circulated again to return to the fuel electrode 2 a via the catch tank 8, the check valve 11, and the ejector 7.

  At this time, since the solenoid 66 of the scavenging gas introduction valve 6 is turned off by the control device, the valve body 69 and the plunger 62 are moved to the valve seat 68 side by the elastic force F2 of the valve spring SP. The cushioning material 69b is pressed against the valve seat 68 and the valve seat 68 is closed. Then, the introduction port 61a is shut off, and the oxidant gas (scavenging gas) does not flow to the fuel gas circulation passage 3b side, and scavenging is stopped.

  As described above, in the present embodiment, when the fuel cell 2 generates power, the scavenging gas introduction valve 6 blocks communication between the fuel gas flow path 3 and the oxidant gas flow path 4, so that the fuel gas and the oxidant gas Is prevented from mixing. Thereby, the fuel cell 2 can prevent the fuel electrode 2a from coming into contact with the gas in which the fuel gas and the oxidant gas are mixed and being oxidized and deteriorated.

  When the fuel cell system 1 is in operation, the pressure P on the outlet port 61b (fuel electrode 2a) side of the scavenging gas introduction valve 6 shown in FIG. 2 is higher than the pressure Q on the inlet port 61a (oxidant electrode 2b) side. The valve body 69 is pressed against the valve seat 68 by the pressure difference. Accordingly, during operation of the fuel cell system 1, the valve body 69 can reliably close the valve seat 68 unless the valve body 69 is opened, so that the fuel gas in the fuel gas flow passage 3 and the oxidant gas flow The oxidant gas in the passage 4 and the communication passage 5 is not mixed.

  Furthermore, the area S1 of the valve body 69 on the side in contact with the fuel gas (high-pressure side flow passage) is larger than the area S2 of the opening of the valve seat 68, so that the valve body 69 contains fuel gas (high-pressure side flow passage). Since the pressure is pressed against the valve seat 68, the valve body 69 reliably closes the valve seat 68.

  By the way, in the above-described fuel cell system of Patent Document 1, when the inlet side (oxidant gas side) of the fuel electrode passage switching valve is arranged on the valve open side and the outlet side (fuel side) is arranged on the valve close side, In the pressure balance during normal operation, pressure acts in the direction to open the fuel electrode passage switching valve. Thereby, since the valve body is pressed to the open side, the fuel gas easily leaks to the oxidant gas side, and there is a problem in the sealing performance of the valve body.

  On the other hand, in the fuel cell system 1 according to the embodiment of the present invention, as described above, for example, the valve element 69 is reliably connected to the valve seat 68 without increasing the spring load (elastic force F2) of the valve spring SP. Can be closed, the sealing performance of the valve body 69 can be improved.

  The present invention is not limited to the above-described embodiment, and various modifications and changes can be made within the scope of the technical idea. The present invention extends to these modifications and changes. Of course.

≪Modification≫
FIG. 4 is a block diagram showing a modification of the fuel cell system according to the embodiment of the present invention.
As shown in FIG. 4, the scavenging gas introduction valve 6 shown in FIG. 1 is only in one direction from the oxidant gas flow passage 4 and the communication passage 5 side (low pressure flow passage side) to the fuel gas flow passage 3 (high pressure flow passage side). It may be a check valve B1 that flows.
Further, as shown in FIG. 4, the discharge valve 13 shown in FIG. 1 may be a check valve B2 that flows only in one direction from the fuel gas flow passage 3 to the fuel gas discharge portion 12 (external) side.
Thus, by providing the check valve B1, it is possible to prevent the fuel gas from leaking to the oxidant gas side with a simple configuration. By providing the check valves B1 and B2, it is possible to circulate the fuel gas and scavenge air in the fuel gas circulation system.

1 is a block diagram showing a fuel cell system according to an embodiment of the present invention. It is sectional drawing which shows an example of the scavenging gas introduction valve used for the fuel cell system which concerns on embodiment of this invention. It is a schematic diagram which shows the relationship between the valve body and valve seat of the scavenging gas introduction valve used for the fuel cell system which concerns on embodiment of this invention. It is a block diagram which shows the modification of the fuel cell system which concerns on embodiment of this invention.

Explanation of symbols

1 Fuel Cell System 2 Fuel Cell 3 Fuel Gas Flow Path (High Pressure Side Flow Path)
4 Oxidant gas flow passage (low pressure side flow passage)
5 Communication path 6 Scavenging gas introduction valve (communication blocking means)
68 Valve seat 69 Valve body S1 Area of valve in contact with high-pressure side flow passage S2 Area of valve seat opening B1, B2 Check valve

Claims (4)

A fuel cell that generates electricity by reaction between the fuel gas and the oxidant gas;
A fuel gas flow passage through which the fuel gas flows;
An oxidant gas flow passage through which the oxidant gas flows;
A fuel cell system comprising: a communication passage communicating the fuel gas flow passage and the oxidant gas flow passage;
A fuel cell system comprising a communication blocking means for blocking communication between the fuel gas flow passage and the oxidant gas flow passage during power generation of the fuel cell. The fuel cell system according to claim 1,
The communication blocking means comprises a scavenging gas introduction valve provided on the communication path and provided with a valve body for opening and closing a valve seat,
The scavenging gas introduction valve is provided with the valve body in communication with a high pressure side flow passage having a high pressure in the fuel gas flow passage and the oxidant gas flow passage,
A fuel cell system, wherein the valve seat is provided in communication with a low pressure side flow passage having a pressure lower than that of the high pressure side flow passage. The fuel cell system according to claim 2, wherein
The fuel cell system according to claim 1, wherein an area of the valve body in contact with the high-pressure side flow passage is larger than an area of the opening of the valve seat. The fuel cell system according to claim 1,
The fuel cell system according to claim 1, wherein the communication blocking means comprises a check valve for preventing a back flow of gas from the fuel gas flow path side to the oxidant gas flow path side.

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