JP2002008691A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease amount of unreacted hydrogen exhausted from a fuel cell. SOLUTION: An exhaust gas pass valve 505 equipped in hydrogen exhaust gas pass 415c of a fuel cell (FC stack) 200, opening and closing the hydrogen exhaust gas pass 415c, and a hydrogen sensor (remaining hydrogen concentration detection means) 601 detecting hydrogen concentration in the FC stack 200, are equipped. When the hydrogen concentration detected by the hydrogen sensor 601 is a 1st predetermined hydrogen concentration d1 or less, the exhaust gas pass valve 505 is opened. When it is a 2nd predetermined hydrogen concentration d2 or more which is higher than the 1st predetermined hydrogen concentration d1 the exhaust gas pass valve 505 is closed. Thus, by intermittently supplying hydrogen to the FC stack 200 from a hydrogen supply means 100, when hydrogen concentration is high, hydrogen can be made to fully react by keeping hydrogen rich gas in the FC stack 200, and a remaining gas can be exhausted after hydrogen concentration becomes low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell system comprising a fuel cell which generates electric energy by a chemical reaction between hydrogen and oxygen, and is effective when applied to a moving body such as a vehicle, a ship and a portable generator. It is.

[0002]

2. Description of the Related Art As described above, a fuel cell generates electric power by chemically reacting hydrogen and oxygen. Therefore, it is necessary to supply hydrogen and oxygen in accordance with the required amount of electric power.

[0003]

Even if hydrogen is supplied to a fuel cell, it is difficult to use 100% of the hydrogen, so that unreacted hydrogen is released together with exhaust gas (steam, carbon dioxide, etc.).

Generally, the amount of hydrogen actually supplied to the fuel cell is set to be larger than the theoretical value in consideration of the amount of unreacted hydrogen. For this reason, it is difficult to reduce the amount of unreacted hydrogen discharged from the fuel cell.

In view of the above, an object of the present invention is to reduce the amount of unreacted hydrogen discharged from a fuel cell.

[0006]

According to the first aspect of the present invention, there is provided a fuel cell (20) for generating electric energy by a chemical reaction between hydrogen and oxygen.
0), a hydrogen supply means (100) for supplying hydrogen to the fuel cell (200), and a hydrogen exhaust passage (415c) through which exhaust after hydrogen is consumed in the fuel cell (200) passes. An exhaust passage valve (505) for opening and closing the hydrogen exhaust passage (415c), and opening and closing the exhaust passage valve (505) according to the amount of hydrogen consumed in the fuel cell (200); Fuel cell (20
0) intermittently supplying hydrogen.

Accordingly, when the hydrogen concentration in the fuel cell (200) is high, the exhaust gas valve (505) is closed and the hydrogen-rich gas is retained in the fuel cell (200) so that hydrogen is sufficiently reacted. be able to. When the hydrogen concentration in the fuel cell (200) decreases, the exhaust passage valve (505) is opened to discharge the residual gas with the reduced hydrogen concentration in the fuel cell (200) and to release new hydrogen-rich gas. Supply. Thereby, the fuel cell (2
00) can be reduced.

[0008] More specifically, as in the second aspect of the present invention, there is provided a residual hydrogen concentration detecting means (601) for detecting the hydrogen concentration in the fuel cell (200), and the residual hydrogen concentration detecting means (601). If the detected hydrogen concentration detected by the above is not more than the predetermined residual hydrogen concentration (d1), the exhaust passage valve (50)
5) Open, and the detected hydrogen concentration becomes the predetermined residual hydrogen concentration (d1)
When the concentration is higher than the second predetermined residual hydrogen concentration (d2),
By closing the exhaust passage valve (505), hydrogen can be intermittently supplied from the hydrogen supply means (100) to the fuel cell (200).

[0009] Specifically, the residual hydrogen concentration detecting means may be a hydrogen sensor (60) for detecting the hydrogen concentration at at least one point in the fuel cell (200).
According to the fourth aspect of the present invention, the hydrogen concentration in the fuel cell (200) can be detected based on the power generation amount of the fuel cell (200). Also, as in the invention according to claim 5, a timer in which a predetermined time associated with the hydrogen consumption in the fuel cell (200) is set in advance can be used.

Further, in the invention according to claim 6, a hydrogen inflow passage (415a) through which hydrogen flowing into the fuel cell (200) passes, and an upstream side of the exhaust passage valve (505) in the hydrogen exhaust passage (415c). A hydrogen circulation path (700) connecting the hydrogen circulation path (700) and the hydrogen circulation path (700).
The hydrogen-containing gas is circulated through the fuel cell (200) through the fuel cell (200).

By circulating the hydrogen-containing gas in the fuel cell (200) in this manner, the hydrogen concentration in the fuel cell (200) can be made uniform, and the hydrogen concentration in the fuel cell (200) accompanying the decrease in the hydrogen concentration can be increased. A decrease in the amount of hydrogen permeating the polymer membrane can be suppressed. Thereby, a decrease in the power generation of the fuel cell (200) due to a decrease in the hydrogen concentration can be suppressed.

Further, by circulating a hydrogen-containing gas through the fuel cell (200), a flow velocity of hydrogen is generated, and the fuel cell (2)
The hydrogen easily contacts the polymer film and the electrode (negative electrode) in the (00). Thereby, permeation of hydrogen into the polymer membrane can be promoted, and a decrease in the amount of hydrogen permeating the polymer membrane can be further suppressed.

[0013] In the invention according to claim 7, the inflow passage valve (506) is provided in the hydrogen inflow passage (415a) through which the hydrogen flowing into the fuel cell (200) passes, and opens and closes the hydrogen inflow passage (415a). ) And a hydrogen circulation passage (70) connecting the upstream side of the exhaust passage valve (505) in the hydrogen exhaust passage (415c) and the downstream side of the inflow passage valve (506) in the hydrogen inflow passage (415a).
0), and hydrogen is circulated to the fuel cell (200) through the hydrogen circulation passage (700).

According to the present invention, the hydrogen circulation passage (700) has a hydrogen circulation pump (701) for circulating a hydrogen-containing gas to the fuel cell (200) through the hydrogen circulation passage (700). Is provided.

Further, in the ninth aspect of the present invention, the hydrogen circulation pump (701) operates when the exhaust passage valve (505) is closed.

According to the tenth aspect of the present invention, a hydrogen concentration detecting means (702) for detecting a hydrogen concentration at a branch point between the hydrogen exhaust passage (415c) and the hydrogen circulation passage (700).
When the hydrogen concentration detected by the hydrogen concentration detecting means (702) is equal to or lower than the predetermined hydrogen concentration (d3), the exhaust passage valve (505) is opened.

With such a configuration, the fuel cell (20
A portion having a low hydrogen concentration in the hydrogen-containing gas circulating through 0) can be selectively discharged from the fuel cell (200), and the hydrogen concentration of the hydrogen-containing gas circulating through the fuel cell (200) can be increased. Can be. Thus, it is possible to suppress a decrease in power generation of the fuel cell (200) due to a decrease in the hydrogen concentration.

Further, according to the present invention, a hydrogen concentration detecting means (702) for detecting a hydrogen concentration at a branch point between the hydrogen exhaust passage (415c) and the hydrogen circulation passage (700).
When the hydrogen concentration detected by the hydrogen concentration detecting means (702) is equal to or less than the predetermined hydrogen concentration (d3), the exhaust passage valve (505) is opened, and when the exhaust passage valve (505) is further opened. Inflow passage valve (50
6) is opened.

In the case where the fuel cell (200) is provided with an exhaust passage valve (505) and an inflow passage valve (506), the exhaust passage valve (505) is provided according to the invention as set forth in claim 11. By opening the inflow passage valve (506) when is opened, it is possible to efficiently supply the hydrogen-rich gas to the fuel cell (200) and discharge the residual gas.

Further, the hydrogen concentration detecting means is, specifically,
According to a twelfth aspect of the present invention, the hydrogen exhaust passage (41
A hydrogen sensor (702) for detecting a hydrogen concentration at a branch point between 5c) and the hydrogen circulation path (700) may be provided, or a hydrogen exhaust path (415c) and a hydrogen exhaust path (415c) may be provided. The hydrogen concentration at the branch point can be indirectly detected based on a physical quantity related to the hydrogen concentration at the branch point with the hydrogen circulation passage (700).

The indirect detection of the hydrogen concentration at the branch point based on the physical quantity related to the hydrogen concentration includes, for example, a current detector (current detecting means) for detecting the power generation amount of the fuel cell (200), A timer in which a predetermined time associated with the hydrogen consumption in the fuel cell (200) is set in advance, a pressure sensor (pressure detecting means) for detecting a gas pressure in the fuel cell (200), or the like can be used.

Further, in the invention according to claim 14, the hydrogen-containing gas coming out of the fuel cell (200) is recirculated to the fuel cell (200) through the circulation passage (700) with the first gas. The second exhausting from the exhaust passage (505)
And a gas separation means (704) for separating the gas from the gas.

The gas separation means (704) may be as follows.
As in the invention described in Item 5, when a gas capable of selectively separating hydrogen is used, the hydrogen-containing gas circulating in the fuel cell (200) is changed to hydrogen (first gas) and other gases (second gas). 2), and hydrogen is passed through a hydrogen circulation passage (700).
Gas other than hydrogen and the hydrogen exhaust passage (415c)
Can be discharged from

As a result, the hydrogen concentration of the hydrogen-rich gas circulating in the FC stack 200 can be increased, and a decrease in the power generation of the FC stack 200 due to a decrease in the hydrogen concentration can be suppressed.

When the gas separating means (704) is capable of selectively separating water vapor as in the invention of claim 16, the first gas circulating through the fuel cell (200) is used. The water vapor concentration of the gas can be increased,
It can be used for humidifying the polymer membrane in the fuel cell (200).

According to the seventeenth aspect of the present invention, the exhaust passage valve (50) in the hydrogen exhaust passage (415c) is provided.
A reciprocating flow generation means (800) is provided upstream of (5) and generates a flow of hydrogen-containing gas present in the fuel cell (200) reciprocating in the fuel cell (200).

[0027] With this configuration, the hydrogen concentration in the fuel cell (200) can be made uniform, and the fuel cell (200) can have a uniform hydrogen concentration as the hydrogen concentration decreases. A decrease in the amount of hydrogen permeating the polymer membrane can be suppressed. Thereby, a decrease in the power generation of the fuel cell (200) due to a decrease in the hydrogen concentration can be suppressed.

Further, a flow velocity is generated in the hydrogen of the fuel cell (200), and the hydrogen easily contacts the polymer membrane and the electrode (negative electrode) in the fuel cell (200). Thereby, permeation of hydrogen into the polymer membrane can be promoted, and a decrease in the amount of hydrogen permeating the polymer membrane can be further suppressed.

In the invention described in claim 18, the exhaust passage valve (50) in the hydrogen exhaust passage (415c) is provided.
A reciprocating flow generating means (5) for generating a flow of hydrogen-containing gas present in the fuel cell (200) reciprocating in the fuel cell (200) at one of the upstream side of 5) and the hydrogen inflow passage (415a). 800) and a pressure buffer chamber (8
01) is provided.

As described above, the pressure buffer chamber (8) is located on the opposite side of the reciprocating flow generator (800) across the fuel cell (200).
01), the fluctuation of the hydrogen pressure in the fuel cell (200) due to the reciprocating flow generated by the reciprocating flow generating means (800) can be absorbed, and the reciprocating flow of hydrogen in the fuel cell (200) can be absorbed. Can be reliably generated.

According to the nineteenth aspect of the present invention, the inflow passage valve (506) is provided in the hydrogen inflow passage (415a) through which the hydrogen flowing into the fuel cell (200) passes, and opens and closes the hydrogen inflow passage (415a). The fuel cell (200) is provided in one of the upstream side of the exhaust passage valve (505) in the hydrogen exhaust passage (415c) and the downstream side of the inflow passage valve (506) in the hydrogen inflow passage (415a). A reciprocating flow generating means (800) for generating a reciprocating flow in the fuel cell (200) is disposed in the hydrogen inside the fuel cell, and a pressure buffer chamber (801) is provided on the other side.

Further, the invention according to claim 20 is characterized in that when the exhaust passage valve (505) is closed, a reciprocating flow is generated by the reciprocating flow generating means (800).

According to the twenty-first aspect of the present invention, the exhaust passage valve (505) and the inflow passage valve (506).
When both are closed, the reciprocating flow generating means (800)
This generates a reciprocating flow.

Further, in the invention according to claim 22, the reciprocating flow generating means (800) includes a variable inner volume chamber (800a) having a variable inner volume and a variable inner volume of the variable inner volume chamber (800a). And a driving unit (800b) for driving the motor.

Further, the invention according to claim 23 is characterized in that a piezoelectric material whose volume fluctuates by applying a voltage is used as the driving section (800b) of the reciprocating flow generating means (800).

The reference numerals in parentheses of the above means indicate the correspondence with specific means described in the embodiments described later.

[0037]

(First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. In the first embodiment, the fuel cell system according to the present invention is applied to an electric vehicle (hereinafter abbreviated as a vehicle).

FIG. 1 is a schematic diagram showing a fuel cell system according to the first embodiment. As shown in FIG. 1, the fuel cell system according to the first embodiment includes a hydrogen production device (hydrogen supply means) 100 and a fuel cell (FC stack) 200 surrounded by a dashed line.

The hydrogen production apparatus 100 produces (generates) a hydrogen-rich gas containing a large amount of hydrogen from a mixed solution of water and methanol (hereinafter, a methanol-mixed solution), and supplies the hydrogen-rich gas to an FC stack 200 described later. It is a hydrogen production device to supply. The hydrogen production apparatus 100 chemically reacts methanol vapor evaporated (vaporized) with water vapor by a hydrogen production fuel evaporator (hereinafter, evaporator) 110 for evaporating a methanol mixed solution,
The fuel cell system has a fuel reformer (hereinafter, referred to as a reformer) 120 for hydrogen production that reforms into hydrogen, carbon dioxide, and a small amount of carbon monoxide.

The evaporator 110 is configured so that a methanol mixed solution is sent by a first pump 131 from a methanol mixed solution tank 130 mounted on a vehicle and storing the methanol mixed solution.

The FC stack 200 is used for the hydrogen production apparatus 10
0, the hydrogen-rich gas produced and the air (oxygen) undergo a chemical reaction to generate power. The fuel cell system according to the present embodiment is configured to drive the traveling electric motor M by the electric power generated by the FC stack 200. Since the catalytic function of the electrode catalyst in the FC stack 200 is easily reduced by carbon monoxide, in the present embodiment, carbon monoxide generated by oxidizing carbon monoxide generated in the reformer 120 to change it to carbon dioxide is used. The reducer 140 is provided in the hydrogen production apparatus 100.

The air blown to the FC stack 200 is
The air is humidified by the air humidifier 221. FC stack 20
Exhaust gas (water vapor, air, etc.) discharged from 0 is cooled by the dehumidifier 222 to remove and collect moisture. The moisture separated and removed by the dehumidifier 222 is returned to the air humidifier 221 via the condensed water return passage 223, and
It is reused for humidifying the air sent to the C stack 200.

FIG. 2 shows a schematic configuration of the FC stack 200. As shown in FIG. 2, the FC stack 200
The positive electrode side and the negative electrode side are separated with a polymer film interposed therebetween. Air (oxygen) is supplied to the positive electrode side, and hydrogen-rich gas is supplied to the negative electrode side. Therefore, exhaust containing a large amount of water vapor is discharged from the positive electrode side, and unreacted hydrogen gas, carbon dioxide, and the like are discharged from the negative electrode side.

As shown in FIG. 1, a heating fuel (methanol in this embodiment) for heating the evaporator 110 is stored in a methanol fuel tank 300 mounted on a vehicle. The methanol (fuel) stored in the methanol fuel tank 300 is supplied to the evaporator 11 by the second pump 310.
Sent to 0. A portion of the methanol discharged from the second pump 310 is configured to be returned to the methanol fuel tank 300 via the methanol return passage 312. The methanol return passage 312 is opened and closed by a fuel return valve 311.

The outside air is sucked by the air pump 400, and is blown to the hydrogen production apparatus 100 (evaporator 110 and reformer 120) and the FC stack 200.
The combustion exhaust gas generated in the above and the exhaust gas generated in the FC stack 200 flow through the exhaust passages 411 to 414 and are discharged to the atmosphere.

The blast air discharged from the air pump 400 is supplied to the hydrogen production device 1 by the first air distribution valve 501.
00 and the FC stack 200, and the distribution amount is adjusted. The air distributed to the hydrogen production apparatus 100 side by the first air distribution valve 501
By the air distribution valves 502, 503, the evaporator 110,
It is distributed to the reformer 120 and the carbon monoxide reducer 140, and the distribution amount is adjusted.

The methanol supplied from the methanol fuel tank 300 is supplied to the evaporator 110 and the reformer 120 by the methanol valve 504, and the supply amount is adjusted.

The hydrogen-rich gas supplied from the hydrogen production apparatus 100 is supplied to the FC stack 20 via the hydrogen passage 415.
0 and discharged through a hydrogen passage 415. More specifically, first, the hydrogen-rich gas supplied from the hydrogen production apparatus 100 is supplied to the F-rich gas through the hydrogen inflow passage 415a.
It flows into the C stack 200 (negative electrode side). The hydrogen flowing into the FC stack 200 passes through the in-stack passage 415b, and is consumed by a chemical reaction with oxygen for power generation. FC
The residual gas after hydrogen is consumed in the stack 200 is
It is discharged from the hydrogen exhaust passage 415c on the negative electrode side of the FC stack 200.

The hydrogen exhaust passage 415c is provided with an exhaust passage valve 505 for opening and closing the hydrogen exhaust passage 415c. The exhaust passage valve 505 is connected to the hydrogen exhaust passage 41.
By opening and closing 5c, the supply of the hydrogen-rich gas to the FC stack 200 and the discharge of the residual gas are controlled. In the first embodiment, the exhaust port 415 on the negative electrode side is used.
Exhaust from c is also released to the atmosphere similarly to the exhaust passage 414 side.

FIG. 3 is a control block diagram of the fuel cell system. As shown in FIGS. 1 and 3, the fuel cell system according to the present embodiment includes an FC stack 200 (negative electrode side).
A hydrogen sensor (residual hydrogen amount detection means) 601 for detecting the concentration of hydrogen (the amount of hydrogen) present in the gas sensor is provided. FIG.
As shown in (1), the detection signal of the hydrogen sensor 601 is input to an FC system controller (hereinafter, FCCU) 600 that controls the entire fuel cell system. And the first to third
Air distribution valves 501-503, methanol valve 50
4 and the exhaust passage valve 505 are controlled by the FCCU 600 based on the detection signal of the hydrogen sensor 601 and the detection signal of the sensor group S for detecting the operating state such as the temperature of the FC stack 200 and the load of the traveling electric motor.

Next, the operation of the exhaust passage valve 505 of the fuel cell system according to the first embodiment will be described with reference to FIG. FIG. 5 is a graph showing the relationship between the amount of hydrogen (residual hydrogen concentration in the FC stack) detected by the hydrogen sensor 601 and the opening / closing timing of the exhaust passage valve 505.

As shown in FIG. 5, the residual hydrogen concentration in the FC stack 200 is reduced to a first predetermined concentration (predetermined residual hydrogen concentration) d.
When the value becomes 1 or less, the exhaust passage valve 505 is opened to supply hydrogen to the FC stack 200. As a result, F from the hydrogen supply facility 100 via the hydrogen inflow passage 415a.
The hydrogen rich gas is supplied to the C stack 200, and the hydrogen concentration in the FC stack 200 increases.

When the hydrogen concentration in the FC stack 200 becomes equal to or higher than the second predetermined concentration d2 which is higher than the first predetermined concentration d1, the exhaust passage valve 505 is closed and the FC stack 20 is closed.
Turn off the hydrogen supply to zero. In the FC stack 200, power is generated by a chemical reaction between hydrogen and oxygen,
Hydrogen is consumed and the hydrogen concentration decreases. As the hydrogen concentration decreases, the power generation amount of the FC stack 200 gradually decreases.

When the hydrogen concentration in the FC stack 200 falls below the first predetermined concentration d1, the exhaust passage valve 505
Is opened, a new hydrogen-rich gas is supplied from the hydrogen supply device 100 to the FC stack 200, and the residual gas having a reduced hydrogen concentration in the FC stack 200 is discharged from the hydrogen exhaust passage 415c.

Thereafter, as shown in FIG.
The opening and closing of the valve 505 is repeated in accordance with the consumption of hydrogen in 00, and hydrogen is intermittently supplied to the FC stack.

As described above, according to the fuel cell system of the first embodiment, the hydrogen discharge passage 415c of the FC stack 200
A hydrogen rich gas can be intermittently (intermittently) supplied to the FC stack 200 by providing an exhaust passage valve 505 and opening and closing the valve 505 according to the amount of hydrogen consumed in the FC stack 200. That is, when the hydrogen concentration in the FC stack 200 is high, the valve 505 is closed to allow the hydrogen rich gas to stay in the FC stack 200 so that the hydrogen is sufficiently reacted. FC stack 20
When the hydrogen concentration within 0 becomes low, the valve 505 is opened to discharge the residual gas having the reduced hydrogen concentration in the FC stack 200 and to supply a new hydrogen-rich gas. Thereby, the amount of unreacted hydrogen discharged from the FC stack 200 can be reduced.

In the first embodiment, only one valve is required to be provided in the hydrogen discharge passage 415c on the downstream side of the FC stack 200.
05 can be easily performed and can be realized at low cost.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 6 shows a schematic configuration of a fuel cell system according to the second embodiment, and FIG. 7 shows a fuel cell 20 of the fuel cell system shown in FIG.
0 is shown. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the first embodiment, the hydrogen discharge passage 41
While hydrogen was supplied to the FC stack 200 and residual gas was discharged to the FC stack 200 by the exhaust passage valve 505 provided in the FC stack 5c, in the second embodiment, as shown in FIGS. The difference is that an inflow passage valve 506 for opening and closing the hydrogen inflow passage 415a is provided in the hydrogen inflow passage 415a on the upstream side of 200.

In this case, similarly to the exhaust passage valve 505, the opening and closing of the inflow passage valve 506 is controlled by the FCCU 600 in accordance with the hydrogen consumption of the FC stack 200.
Hydrogen exhaust passage valve 505 and hydrogen inflow passage valve 506
May open and close at the same timing, or may open and close at different timings. However, in order to efficiently discharge the residual gas in the FC stack 200, it is desirable that there be a time during which the two valves 505 and 506 are simultaneously opened.

With the configuration of the fuel cell system according to the second embodiment, hydrogen can be intermittently (intermittently) supplied to the FC stack 200, and unreacted hydrogen discharged from the FC stack 200 can be supplied. The amount can be reduced.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 8 shows a schematic configuration of a fuel cell system according to the third embodiment, and FIG. 9 shows a fuel cell 2 of the fuel cell system shown in FIG.
The vicinity of 00 is shown. The third embodiment is different from the fuel cell system of the second embodiment in that the FC stack 2
The difference is that a hydrogen circulation passage 700 for circulating hydrogen is provided at 00. The same parts as those in the second embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the first embodiment, as described with reference to FIG. 5, hydrogen is consumed with power generation, and the hydrogen concentration in the FC stack 200 decreases. Due to the decrease in the hydrogen concentration in the FC stack 200, the FC stack 200
Power generation decreases. It is considered that the decrease in the hydrogen concentration in the FC stack 200 occurs as follows.

First, hydrogen existing on the negative electrode side in the FC stack 200 touches the polymer film, diffuses, passes through the polymer film, and moves to the positive electrode side. Furthermore, FC stack 200
Hydrogen near the surface of the inner electrode (negative electrode) contacts the electrode and becomes hydrogen ions, which are pulled by oxygen ions present on the positive electrode side by Coulomb force, pass through the polymer membrane, and move to the positive electrode side. Thereby, the hydrogen concentration decreases on the negative electrode side in the FC stack 200. At this time, in the FC stack 200, the hydrogen concentration does not decrease uniformly, and the hydrogen concentration in the vicinity of the polymer film and the electrode significantly decreases.

In the fuel cell system of each of the above embodiments, in order to reduce the amount of unreacted hydrogen discharged from the FC stack 200, the exhaust passage valve 505 is closed to allow the hydrogen rich gas to stay in the FC stack 200. I have. Therefore, in the FC 200 stack 200, the residual gas having a reduced hydrogen concentration is not agitated, and the hydrogen concentration is maintained in a non-uniform state.

Therefore, in the fuel cell system according to the third embodiment, as shown in FIGS.
Exhaust valve 505 in the hydrogen discharge passage 415c
And the downstream side of the inflow passage valve 506 in the hydrogen inflow passage 415a are connected by a hydrogen circulation passage 700. A hydrogen circulation pump 701 for circulating hydrogen to the FC stack 200 is provided in the hydrogen circulation passage 700.
Is provided.

With such a configuration, the two valves 50
By operating the hydrogen circulation pump 701 in a state where 5, 506 is closed, the hydrogen-containing gas in the FC stack 200 is discharged from the FC stack 200 → the hydrogen exhaust passage 415c → the hydrogen circulation passage 700 → the hydrogen inflow passage 415a → the FC stack 200 Circulate in order.

By circulating the hydrogen-containing gas through the FC stack 200 in this way, the hydrogen concentration in the FC stack 200 can be made uniform, and the FC concentration accompanying the hydrogen concentration decrease can be increased.
A decrease in the amount of hydrogen permeating the polymer membrane in the stack 200 can be suppressed. Thereby, the FC stack 20
A decrease in the power generation of the FC stack 200 due to a decrease in the hydrogen concentration within 0 can be suppressed.

Further, by circulating the hydrogen through the FC stack 200, a flow velocity is generated in the hydrogen, so that the hydrogen easily contacts the polymer film and the electrode (negative electrode) in the FC stack 200. Thereby, permeation of hydrogen into the polymer membrane can be promoted, and a decrease in the amount of hydrogen permeating the polymer membrane can be further suppressed.

In the fuel cell system of the third embodiment, two valves 505 and 506 are provided on the upstream side and the downstream side of the FC stack 200. However, as shown in FIG. May be omitted, and only the exhaust passage valve 505 on the downstream side may be provided. In the fuel cell system having such a configuration, the pump 701 closes the FC stack 2 with the exhaust passage valve 505 closed.
When the hydrogen is circulated through the fuel cell stack 200, the average pressure in the FC stack 200 does not change.
The same effect as when two valves are provided upstream and downstream of 00 is obtained.

Further, in the third embodiment, hydrogen is converted to FC
Although the stack 200 → the hydrogen exhaust passage 415c → the hydrogen circulation passage 700 → the hydrogen inflow passage 415a → the FC stack 200 are circulated in this order, the hydrogen may be circulated in the reverse direction.

In the third embodiment, hydrogen is circulated through the FC stack 200 with the two valves 505 and 506 closed. However, the present invention is not limited to this.
Hydrogen may be circulated through the FC stack 200 with the 6 open. In this case, a flow velocity is generated in the hydrogen in the FC stack 200, so that the hydrogen easily contacts the polymer film and the electrode (negative electrode) in the FC stack 200, and the effect that hydrogen permeation through the polymer film can be promoted is obtained. Can be

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 11 shows the vicinity of the fuel cell 200 of the fuel cell system according to the fourth embodiment.

The fourth embodiment differs from the fuel cell system of the third embodiment in that the hydrogen-containing gas circulating through the hydrogen circulation passage 700 to the FC stack 200 is different from that of the third embodiment.
The difference is that a portion having a low hydrogen concentration is selectively discharged. Further, the inflow passage valve 50 is provided in the hydrogen inflow passage 415a on the upstream side of the FC stack 200.
6 is not provided. The same parts as those in the third embodiment are denoted by the same reference numerals, and the description is omitted.

As shown in FIG. 11, the fuel cell system according to the fourth embodiment detects the hydrogen concentration of the hydrogen-containing gas circulating through the FC stack 200 at the branch point between the hydrogen exhaust passage 415c and the hydrogen circulation passage 700. A hydrogen sensor (hydrogen concentration detecting means) 702 is provided. Further, a control unit 703 for controlling the opening and closing of the exhaust passage valve 505 is provided. The control unit 703 controls the exhaust passage valve 505 based on the hydrogen concentration detected by the hydrogen sensor 702.

Next, the operation of the hydrogen sensor 702 and the control unit 703 of the fuel cell system according to the fourth embodiment will be described.

First, when the hydrogen-containing gas is circulating through the hydrogen circulation passage 700 to the FC stack 200, the hydrogen sensor 702 circulates the hydrogen-containing gas circulating at the branch point between the hydrogen exhaust passage 415c and the hydrogen circulation passage 700. Measure the hydrogen concentration of the gas. When the hydrogen concentration measured by the hydrogen sensor 702 is equal to or lower than the third predetermined concentration d3, the control unit 703 opens the exhaust passage valve 505. When the hydrogen concentration measured by the hydrogen sensor 702 is equal to or higher than the third predetermined concentration d3,
The exhaust passage valve 505 is closed by the control unit 703.

With such a configuration, the FC stack 20
A portion having a low hydrogen concentration in the hydrogen-containing gas circulating 0 can be selectively discharged from the FC stack 200, and the hydrogen concentration of the hydrogen-containing gas circulating in the FC stack 200 can be increased. Thus, it is possible to suppress a decrease in the power generation of the FC stack 200 due to a decrease in the hydrogen concentration.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 12 shows the vicinity of the fuel cell 200 of the fuel cell system according to the fifth embodiment.

The fifth embodiment differs from the fuel cell system of the third embodiment in that the hydrogen-containing gas circulating through the hydrogen circulation passage 700 to the FC stack 200 is different from that of the third embodiment.
The difference is that a portion having a low hydrogen concentration is selectively discharged. Further, the inflow passage valve 50 is provided in the hydrogen inflow passage 415a on the upstream side of the FC stack 200.
6 is not provided. The same parts as those in the third embodiment are denoted by the same reference numerals, and the description is omitted.

As shown in FIG. 12, in the fuel cell system according to the fifth embodiment, a gas separation device (gas separation means) 704 is provided at a branch point between the hydrogen exhaust passage 415c and the hydrogen circulation passage 700. I have. This gas separation device 704
Is capable of selectively separating hydrogen from the hydrogen-containing gas circulating in the FC stack 200. As the gas separation device 704 for separating hydrogen, for example, a hydrogen separation membrane (a permselective membrane) made of a polyimide membrane can be used.

The gas separating device 704 separates the hydrogen-containing gas circulating in the FC stack 200 into hydrogen (first gas) and other gases (second gas), and the hydrogen is supplied to the hydrogen circulation passage 700 side. And gas other than hydrogen is discharged from the hydrogen exhaust passage 415c. As a result, the hydrogen concentration of the hydrogen-containing gas circulating in the FC stack 200 can be increased, and the FC stack 200 associated with the decrease in the hydrogen concentration can be increased.
Can be suppressed from decreasing.

In the fifth embodiment, the gas separation device 704 capable of selectively separating hydrogen from the hydrogen-containing gas circulating in the FC stack 200 is used. However, the present invention is not limited to this. By using a gas separation device capable of separation, the water vapor concentration of the hydrogen-containing gas circulating in the FC stack 200 may be increased. Thus, FC
By increasing the water vapor concentration of the hydrogen-containing gas circulating in the stack 200, it can be used for humidifying the polymer film in the FC stack 200.

When a fuel cell system is provided with a gas separator for separating hydrogen and a gas separator for separating steam at the same time, a gas separator having both a function of separating hydrogen and a function of separating steam is provided. It may be provided, or two gas separation devices having respective functions may be provided.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described with reference to FIGS. Figure 1
3 shows a schematic configuration of the fuel cell system according to the sixth embodiment, and FIG. 14 shows the fuel cell 20 of the fuel cell system shown in FIG.
0 is shown.

In the sixth embodiment, similarly to the fuel cell system of the third embodiment, a decrease in the amount of hydrogen permeating the polymer membrane in the FC stack 200 due to a decrease in the hydrogen concentration is suppressed. The purpose of the present invention is to suppress a decrease in the power generation of 200.

The sixth embodiment differs from the fuel cell system of the third embodiment in that the hydrogen existing in the FC stack 200 is replaced with hydrogen existing in the FC stack 200 instead of the hydrogen circulation passage 700 for circulating hydrogen in the FC stack 200. The difference is that a reciprocating flow generator 800 for providing a flow reciprocating in the FC stack 200 is provided. The same parts as those in the third embodiment are denoted by the same reference numerals, and the description is omitted.

As shown in FIGS. 13 and 14, the fuel cell system according to the sixth embodiment is provided with a reciprocating flow generator 800 in the hydrogen exhaust passage 415a on the upstream side of the exhaust passage valve 505. The reciprocating flow generator 800 includes an internal volume variable chamber 800a which is in communication with the hydrogen exhaust passage 415c and whose internal volume can be changed.
And a drive unit 800b that varies the internal volume of the internal battery 00a. The reciprocating flow generator 800 increases or decreases the internal volume of the internal volume variable chamber 800a by the driving unit 800b,
This is to generate a flow of hydrogen existing in the FC stack 200 reciprocating in the in-stack passage 415b. In the sixth embodiment, a piezoelectric vibrator (piezoelectric material) that changes in volume by applying a voltage is used as the driving unit 800b.

Further, the opposite side of the reciprocating flow generator 800 with the FC stack 200 interposed therebetween, that is, the hydrogen inflow passage 41
Downstream of the inflow passage valve 506 in FIG.
A pressure buffer chamber 801 for buffering fluctuations in hydrogen pressure in the stack 200 is provided.

With the above configuration, the two valves 5
By operating the reciprocating flow generator 800 with the 05 and 506 closed, it is possible to generate a flow reciprocating in the stack passage 415b in the hydrogen existing in the FC stack 200.

At this time, since the valves 505 and 506 on the upstream and downstream sides of the FC stack 200 are closed,
By increasing or decreasing the internal volume of the internal volume variable chamber 800a in the reciprocating flow generator 800, a pressure fluctuation occurs in the hydrogen of the FC stack 200. In particular, when the inner volume of the inner volume variable chamber 800a is increased, there is no escape for hydrogen, and hydrogen is compressed. As a result, the reciprocating flow of hydrogen in the FC stack 200 may not be generated efficiently.

Therefore, in the sixth embodiment, the pressure buffer chamber 801 is provided on the opposite side of the reciprocating flow generator 800 with the FC stack 200 interposed therebetween.
Fluctuations in the hydrogen pressure in the fuel cell can be absorbed, and the reciprocating flow of hydrogen in the FC stack 200 can be reliably generated.

As described above, according to the fuel cell system of the sixth embodiment, by generating a reciprocating flow of hydrogen in the FC stack 200, the fuel cell system is provided with the same FC as in the third embodiment.
It is possible to make the hydrogen concentration in the stack 200 uniform,
A decrease in the amount of hydrogen permeating the polymer membrane in the FC stack 200 due to a decrease in the hydrogen concentration can be suppressed. As a result, the FC concentration due to a decrease in the hydrogen concentration in the FC stack 200 is reduced.
A decrease in the power generation of the stack 200 can be suppressed.

Further, by reciprocating hydrogen in the FC stack 200, a flow velocity is generated in the hydrogen, and the FC stack 200
The hydrogen easily contacts the polymer film and the electrode (negative electrode) in the inside. Thereby, permeation of hydrogen into the polymer membrane can be promoted, and a decrease in the amount of hydrogen permeating the polymer membrane can be further suppressed.

In the sixth embodiment, the reciprocating flow generator 800 is arranged on the downstream side of the FC stack 200, and the pressure buffer chamber 801 is arranged on the upstream side of the FC stack 200. However, the present invention is not limited to this configuration. Instead, the arrangement of the reciprocating flow generator 800 and the pressure buffer chamber 801 is switched, the reciprocating flow generator 800 is arranged on the upstream side of the FC stack 200, and the pressure buffer chamber 801 is arranged on the downstream side of the FC stack 200. Good.

In the sixth embodiment, the piezoelectric material is used as the driving section 800a of the reciprocating flow generator 800.
However, the invention is not limited to this. For example, a piston that reciprocates inside the internal volume variable chamber 800b may be used as the driving unit 800b, or the internal volume may be changed by an external pressure or external force such as a bellows as the internal volume variable chamber 800b. May be changed, and the internal volume may be changed by a driving unit 800b such as a cam. In the case where a piezoelectric material is used for the driving section 800b as in the sixth embodiment, problems such as hydrogen leakage that is likely to occur when a piston is used and material deterioration that is likely to occur when a bellows is used are problems. Is less likely to occur.

In the sixth embodiment, two valves 505 and 505 are provided upstream and downstream of the FC stack 200.
06 is provided, but is not limited to this, and as shown in FIG.
The inlet valve 506 on the upstream side of the FC stack 200 is omitted, and the valve 505 on the downstream side of the FC stack 200 is omitted.
The same effect can be obtained only by using only this. In this case as well, the reciprocating flow generator 800 can be arranged on either the upstream side or the downstream side of the FC stack 200. However, if it is provided on the downstream side of the FC stack 200, the hydrogen pressure becomes higher than the upstream side of the FC stack 200. Since it can escape to the side, the pressure buffer chamber 801 can be omitted. When the reciprocating flow generator 800 is arranged on the upstream side of the FC stack 200, it is desirable to provide the pressure buffer chamber 801 in the hydrogen exhaust passage 415c on the downstream side of the FC stack 200.

(Other Embodiments) (1) In the first embodiment, the hydrogen concentration at one point in the FC stack 200 is detected by the hydrogen sensor 601.
A plurality of hydrogen sensors are provided in the FC stack 200,
The configuration may be such that the hydrogen concentration at a plurality of points in the stack 200 is detected. In this case, the opening / closing control of the exhaust passage valve 505 is performed based on the hydrogen concentration detected at a plurality of points, and even when the hydrogen concentration in the FC stack 200 is light and dark, the control of the exhaust passage valve 505 is performed. It can be performed accurately. (2) In the first embodiment, the hydrogen sensor 601 is used as the residual hydrogen concentration detecting means, and the hydrogen concentration in the FC stack 200 is directly detected by the hydrogen sensor 601. However, the present invention is not limited to this. The hydrogen concentration in the FC stack 200 may be indirectly detected based on a physical quantity related to the hydrogen concentration.

For example, since the amount of hydrogen consumed by the FC stack 200 is proportional to the amount of current output from the FC stack 200, a current detector (current detecting means) is used as a residual hydrogen concentration detecting means. By detecting the amount of electric power (current amount) output from the stack 200,
The configuration may be such that the residual hydrogen concentration (residual hydrogen amount) in the FC stack 200 is indirectly detected.

Since the amount of hydrogen consumed in the FC stack 200 is related to the time elapsed since hydrogen was supplied to the FC stack 200, the amount of hydrogen consumed in the FC stack 200 is used as a residual hydrogen concentration detecting means. A preset timer associated with the quantity may also use a preset timer.

Further, by using a pressure sensor (pressure detecting means) as the residual hydrogen concentration detecting means and detecting the gas pressure in the FC stack 200 (negative electrode side), the residual hydrogen concentration (residual hydrogen amount) in the FC stack 200 is detected. ) May be configured to be indirectly detected. (3) In the fourth embodiment, the hydrogen sensor 702 is used as the hydrogen concentration detecting means, and the hydrogen sensor 702 directly determines the hydrogen concentration of the hydrogen-containing gas circulating at the branch point between the hydrogen exhaust passage 415c and the hydrogen circulation passage 700. Detected,
Not limited to this, the hydrogen exhaust passage 415c and the hydrogen circulation passage 7
The hydrogen concentration may be indirectly detected based on a physical quantity related to the hydrogen concentration of the hydrogen-containing gas circulating at the branch point of 00.

For example, similarly to the residual hydrogen concentration detecting means (2), a current detector (current detecting means) for detecting the power generation amount of the FC stack 200, a predetermined time period associated with the hydrogen consumption amount in the FC stack 200 Using a preset timer, a pressure sensor (pressure detecting means) for detecting a gas pressure in the FC stack 200 (negative electrode side), or the like, to circulate hydrogen to a branch point between the hydrogen exhaust passage 415c and the hydrogen circulation passage 700. The hydrogen concentration of the contained gas can be detected indirectly.

Further, it is not always necessary to detect the hydrogen concentration near the branch point between the hydrogen exhaust passage 415c and the hydrogen circulation passage 700, and the hydrogen concentration at a position distant from the branch point by the above-mentioned hydrogen sensor or pressure sensor is used. It may be detected. In this case, the controller 703 controls the opening and closing of the exhaust passage valve 505 in consideration of the flow rate of the hydrogen-containing gas circulating in the FC stack 200. For example, if it takes one second for the hydrogen-containing gas at the position where the hydrogen concentration is detected to reach the branch point between the hydrogen exhaust passage 415c and the hydrogen circulation passage 700, the detected hydrogen concentration becomes equal to or less than the third predetermined concentration d3. One second after that, the exhaust passage valve 505 may be opened. (4) In each of the above embodiments, the present invention is applied to an electric vehicle. However, the present invention is not limited to this, and can be applied to a stationary fuel cell system such as for home use. (5) Further, in each of the above embodiments, the hydrogen production apparatus 100 that reforms a hydrocarbon-based fuel to produce a hydrogen-rich gas containing a large amount of hydrogen is used as the hydrogen supply means.
The present invention is not limited to this, and a high-pressure hydrogen tank capable of supplying pure hydrogen gas, a hydrogen tank using a hydrogen storage alloy, or the like may be used as the hydrogen supply means.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram of an FC stack.

FIG. 3 is a control block diagram of the fuel cell system according to the first embodiment of the present invention.

FIG. 4 is an enlarged schematic diagram showing the vicinity of a fuel cell of the fuel cell system shown in FIG.

FIG. 5 is a graph showing an opening / closing timing of an exhaust passage valve 505 with respect to a hydrogen amount (residual hydrogen concentration in an FC stack) detected by a hydrogen sensor.

FIG. 6 is a schematic diagram of a fuel cell system according to a second embodiment of the present invention.

FIG. 7 is an enlarged schematic diagram showing the vicinity of a fuel cell of the fuel cell system shown in FIG.

FIG. 8 is a schematic diagram of a fuel cell system according to a third embodiment of the present invention.

9 is an enlarged schematic diagram showing the vicinity of a fuel cell of the fuel cell system shown in FIG.

FIG. 10 is an enlarged schematic diagram showing the vicinity of a fuel cell in a modified example of the fuel cell system shown in FIG.

FIG. 11 is an enlarged schematic diagram showing the vicinity of a fuel cell of a fuel cell system according to a fourth embodiment of the present invention.

FIG. 12 is an enlarged schematic diagram showing the vicinity of a fuel cell of a fuel cell system according to a fifth embodiment of the present invention.

FIG. 13 is a schematic diagram of a fuel cell system according to a sixth embodiment of the present invention.

FIG. 14 is an enlarged schematic diagram showing the vicinity of a fuel cell of the fuel cell system shown in FIG.

FIG. 15 is an enlarged schematic view showing the vicinity of a fuel cell in a modified example of the fuel cell system shown in FIG.

[Explanation of symbols]

100: hydrogen production apparatus (hydrogen supply means), 200: FC
Stack (fuel cell), 415a ... hydrogen inflow passage, 41
5c: hydrogen exhaust passage, 505: exhaust passage valve, 506
.., Inflow passage valve, 601, hydrogen sensor (residual hydrogen concentration detection means), 700, hydrogen circulation passage, 701, hydrogen circulation pump, 702, hydrogen sensor (hydrogen concentration detection means), 8
00: reciprocating flow generator (reciprocating flow generating means), 801: pressure buffer chamber.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masanori Uehara 1-1-1 Showa-cho, Kariya-shi, Aichi F-Term in Denso Co., Ltd. 5H026 AA06 5H027 AA02 AA06 BA01 BA16 BA19 KK05 KK31 KK51 KK56 MM08 MM09 5H115 PG04 PI18 PU01 QN12 TI06 TI10

Claims (23)

[Claims] 1. A fuel cell (200) for generating electric energy by a chemical reaction between hydrogen and oxygen; a hydrogen supply means (100) for supplying hydrogen to the fuel cell (200); and the fuel cell (200). Is provided in a hydrogen exhaust passage (415c) through which the exhaust gas after the consumption of hydrogen passes.
An exhaust passage valve (505) for opening and closing the hydrogen exhaust passage (415c), wherein the hydrogen supply means opens and closes the exhaust passage valve (505) according to the amount of hydrogen consumed in the fuel cell (200). A fuel cell system characterized by intermittently supplying hydrogen from (100) to said fuel cell (200). 2. A fuel cell system comprising: a residual hydrogen concentration detecting means for detecting a hydrogen concentration in the fuel cell; wherein the detected hydrogen concentration detected by the residual hydrogen concentration detecting means is a first predetermined residual hydrogen concentration. When the hydrogen concentration is equal to or less than the hydrogen concentration (d1), the exhaust passage valve (505) is opened to supply hydrogen to the fuel cell (200), and the detected hydrogen concentration is higher than the predetermined residual hydrogen concentration (d1). When the residual hydrogen concentration (d2) or more, the exhaust passage valve (50
5) A fuel cell system, wherein the supply of hydrogen is stopped by closing. 3. The fuel cell according to claim 2, wherein said residual hydrogen concentration detecting means is a hydrogen sensor (601) for detecting at least one point of hydrogen concentration in said fuel cell (200). apparatus. 4. The fuel cell system according to claim 1, wherein the residual hydrogen concentration detecting means is configured to detect the fuel cell (20) based on a power generation amount of the fuel cell (200).
3. The fuel cell device according to claim 2, wherein the hydrogen concentration in 0) is detected. 5. The fuel cell according to claim 2, wherein the residual hydrogen concentration detecting means is a timer in which a predetermined time associated with a hydrogen consumption in the fuel cell is set in advance. apparatus. 6. A hydrogen inlet passage (415a) through which hydrogen flowing into the fuel cell (200) passes, and the exhaust passage valve (50) in the hydrogen exhaust passage (415c).
5) a hydrogen circulation passage (70)
0), wherein the hydrogen-containing gas present in the fuel cell (200) is circulated to the fuel cell (200) through the hydrogen circulation passage (700). 6. The fuel cell system according to any one of 5. 7. A hydrogen inlet passage (415a) through which hydrogen flowing into the fuel cell (200) passes,
An inflow passage valve (506) for opening and closing the hydrogen inflow passage (415a); an upstream side of the exhaust passage valve (505) in the hydrogen exhaust passage (415c);
a) a hydrogen circulation path (700) connecting the downstream side of the inflow path valve (506) with the hydrogen-containing gas present in the fuel cell (200). 6. The fuel cell system according to claim 1, wherein the fuel cell circulates through the fuel cell. 8. The fuel cell (20) is connected to the hydrogen circulation passage (700) through the hydrogen circulation passage (700).
0) a hydrogen circulation pump (70) for circulating a hydrogen-containing gas.
8. The fuel cell system according to claim 6, wherein 1) is provided. 9. The fuel cell system according to claim 8, wherein the hydrogen circulation pump (701) operates when the exhaust passage valve (505) is closed. 10. A hydrogen concentration detecting means (702) for detecting a hydrogen concentration at a branch point between the hydrogen exhaust passage (415c) and the hydrogen circulation passage (700), wherein the hydrogen concentration detecting means (702) detects the hydrogen concentration. The fuel cell system according to any one of claims 6 to 9, wherein the exhaust passage valve (505) is opened when the determined hydrogen concentration is equal to or lower than a predetermined hydrogen concentration (d3). 11. A hydrogen concentration detecting means (702) for detecting a hydrogen concentration at a branch point between the hydrogen exhaust passage (415c) and the hydrogen circulation passage (700), and the hydrogen concentration detecting means (702) detects the hydrogen concentration. When the measured hydrogen concentration is equal to or lower than the predetermined hydrogen concentration (d3), the exhaust passage valve (505) is opened, and when the exhaust passage valve (505) is open, the inflow passage valve (506) is opened. 10. The method according to claim 7, wherein:
The fuel cell system according to any one of the above. 12. A hydrogen sensor (702) for detecting a hydrogen concentration at a branch point between the hydrogen exhaust passage (415c) and the hydrogen circulation passage (700). The fuel cell system according to claim 10 or 11. 13. The hydrogen concentration detecting means indirectly detects the hydrogen concentration at the branch point based on a physical quantity related to the hydrogen concentration at a branch point between the hydrogen exhaust passage (415c) and the hydrogen circulation passage (700). The fuel cell system according to claim 10, wherein the fuel cell system is configured to detect the fuel cell system. 14. A first gas for recirculating the hydrogen-containing gas coming out of the fuel cell (200) to the fuel cell (200) through the circulation passage (700), and the exhaust gas passage (505). The fuel cell system according to any one of claims 6 to 13, further comprising gas separation means (704) for separating the gas into a second gas to be exhausted. 15. The gas separation means (704) capable of selectively separating hydrogen, wherein the first gas has a higher hydrogen concentration than the second gas. Fuel cell system. 16. The gas separation means according to claim 14, wherein said gas separation means is capable of selectively separating water vapor, and said first gas has a higher water vapor concentration than said second gas. Fuel cell system. 17. A hydrogen exhaust passage (415c) disposed upstream of the exhaust passage valve (505) in the hydrogen exhaust passage (415c),
6. A reciprocating flow generating means (800) for generating a reciprocating flow of hydrogen-containing gas present in the fuel cell (200) in the fuel cell (200). A fuel cell system according to one of the preceding claims. 18. The fuel cell (2) is connected to one of an upstream side of the exhaust passage valve (505) in the hydrogen exhaust passage (415c) and a hydrogen inflow passage (415a).
00) to the hydrogen-containing gas present in the fuel cell (20).
0), a reciprocating flow generating means (8)
The fuel cell system according to any one of claims 1 to 5, wherein a pressure buffer chamber (801) is provided on the other side. 19. An inflow passage valve (506) provided in the hydrogen inflow passage (415a) through which hydrogen flowing into the fuel cell (200) passes, the inflow passage valve (506) opening and closing the hydrogen inflow passage (415a), An exhaust passage (415c) upstream of the exhaust passage valve (505) and the hydrogen inflow passage (415);
a) a reciprocating flow generating means for generating a flow of hydrogen-containing gas in the fuel cell (200) reciprocating in the fuel cell (200) at one of the downstream sides of the inflow passage valve (506) in The fuel cell system according to any one of claims 1 to 5, wherein (800) is provided, and a pressure buffer chamber (801) is provided on the other side. 20. The method according to claim 17, wherein the reciprocating flow is generated by the reciprocating flow generating means when the exhaust passage valve is closed. The fuel cell system as described. 21. The reciprocating flow generating means (800) generates the reciprocating flow when both the exhaust passage valve (505) and the inflow passage valve (506) are closed. Item 20. The fuel cell system according to any one of items 17 to 19. 22. The reciprocating flow generating means (800) includes a variable internal volume chamber (800a) having a variable internal volume, and a drive unit (800b) configured to vary the internal volume of the variable internal volume chamber (800a). 2. The method according to claim 1, further comprising:
22. The fuel cell system according to any one of 7 to 21. 23. The driving unit (800b) of the reciprocating flow generating means (800) is made of a piezoelectric material whose volume changes by applying a voltage.
2. The fuel cell system according to claim 1,