JPH07272740A - Control device for fuel cell system - Google Patents

Abstract

PURPOSE:To provide a control device for a fuel cell system formed so as to suppress generation of a pressure difference between both electrodes after an operation is stopped in a high polymer electrolytic fuel cell generating power by receiving supply of oxygen or air and hydrogen. CONSTITUTION:A system A, generating power by receiving supply of oxygen and hydrogen, has an inert gas cylinder 40 of nitrogen or the like. When an operation is stopped, reaction gas supplying opening/closing valves 6, 19 are both closed, to stop supply of reaction gas relating to a fuel cell 1. Thereafter, an inert gas supplying opening/closing valve 46 and exhaust use opening/closing valves 14, 25 are immediately opened for a fixed time, to substitute inert gas for the reaction gas in the fuel cell 1. Thus in the fuel cell 1, its power generation is stopped simultaneously with its operation stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a fuel cell system, and more particularly to a system incorporating a solid polymer electrolyte fuel cell for generating electric power by reacting hydrogen with oxygen or air.

[0002]

2. Description of the Related Art Recently, electric vehicles have been drawing attention to environmental problems, that is, air pollution, and electric vehicles equipped with a storage battery have already been put into practical use. However, battery-powered vehicles have difficult problems to solve, such as a relatively short mileage and a long charging time due to the storage capacity of the battery. The advent of battery-powered vehicles is awaited (Japanese Patent Laid-Open No. 2-168).
803).

Some fuel cells include US Pat. No. 4,988,5.
As seen in Japanese Patent No. 83, a solid polymer electrolyte fuel cell (PEFC) that generates electric power by reacting hydrogen with oxygen or air is known, and future development of fuel cells for automobiles is considered. Therefore, it is considered desirable to use a solid polymer electrolyte fuel cell because the outflow of the liquid electrolyte can be avoided.

[0004]

By the way, even if the supply of the reaction gas is stopped in order to stop the operation of the fuel cell,
Power generation is sustained by the reaction gas remaining in the fuel cell. Here, in the case of a solid polymer electrolyte fuel cell that generates electricity by the reaction of hydrogen and oxygen or air, the reaction formula as a whole is that 1 mol of H ₂ and 1/2 mol of O ₂ react with each other. It is in a relationship to generate 1 mol of H ₂ O. Therefore, after the operation is stopped, hydrogen remaining in the fuel cell consumes a larger amount than oxygen or air. Therefore, the pressure on the fuel electrode side relatively decreases significantly, and the fuel that sandwiches the electrolyte layer is reduced. There is a problem that a large pressure difference occurs between the electrode side and the oxidant electrode side. This problem, that is, the pressure difference generated between the two electrodes after the operation is stopped, may cause the performance deterioration of battery components such as the electrolyte membrane.

Therefore, an object of the present invention is to prevent the generation of a pressure difference between the two electrodes after the operation is stopped in a solid polymer electrolyte fuel cell which is supplied with oxygen or air and hydrogen to generate electric power. To provide a control device for the system.

[0006]

In order to achieve such a technical object, in the first invention, a solid polymer electrolyte fuel cell system for generating electric power by supplying a reaction gas composed of hydrogen and oxygen. As a premise, a first opening / closing valve provided in the reaction gas supply system of the fuel cell to open / close the supply of the reaction gas to the fuel cell and an exhaust pipe for discharging the excess reaction gas discharged from the fuel cell to the outside of the system. A second on-off valve provided, an inert gas source attached to the reaction gas supply system of the fuel cell, and a third opening and closing supply of the inert gas stored in the inert gas source to the fuel cell When the operation of the on-off valve and the fuel cell is stopped, the first on-off valve is closed, and the second on-off valve and the third on-off valve are opened for a predetermined time so that the inside of the fuel cell is closed. Control to replace the reaction gas with an inert gas It is constituted and a stage.

Further, in the second aspect of the invention, the solid polymer electrolyte fuel cell system which receives the supply of hydrogen and air to generate electric power is premised, and the solid polymer electrolyte fuel cell system is provided in the air supply system of the fuel cell to provide air to the fuel cell. A first opening / closing valve that opens and closes the supply of the fuel cell, a storage unit that is attached to the air supply system of the fuel cell and stores the reacted air discharged from the fuel cell, and the reacted air that is stored in the storage unit. A second opening / closing valve for opening and closing the supply to the fuel cell; and a second opening / closing valve for closing the first opening / closing valve and a second opening / closing valve for stopping the operation of the fuel cell. And a control means for replacing the reaction gas with the reacted air.

Further, according to the third aspect of the invention, the solid polymer electrolyte fuel cell system which receives the supply of hydrogen and oxygen to generate electric power is premised on the hydrogen supply system for supplying hydrogen to the fuel cell. A first on-off valve, a second on-off valve provided in a hydrogen recirculation system that returns hydrogen discharged from the fuel cell to the hydrogen supply system, and an oxygen supply system that supplies oxygen to the fuel cell. A third opening / closing valve, a fourth opening / closing valve provided in an oxygen recirculation system that returns oxygen discharged from the fuel cell to the oxygen supply system, and the third opening / closing valve when the operation of the fuel cell is stopped. Control means for closing the first to fourth opening / closing valves, wherein the first to fourth opening / closing valves are the first opening / closing valves when the first to fourth opening / closing valves are closed. The equivalent of hydrogen remaining between the valve and the second on-off valve, and the third As equivalent of oxygen remaining in between the opening and closing valve to the fourth on-off valve are substantially equal, it is constituted that the mounting position is set.

Further, according to the fourth aspect of the invention, the solid polymer electrolyte fuel cell system which receives the supply of hydrogen and air to generate electric power is premised on the hydrogen supply system for supplying hydrogen to the fuel cell. A first on-off valve, a second on-off valve provided in a hydrogen recirculation system that returns hydrogen discharged from the fuel cell to the hydrogen supply system, and an air supply system that supplies air to the fuel cell. A third opening / closing valve, a fourth opening / closing valve provided in an exhaust system for discharging the reacted air discharged from the fuel cell to the outside of the system, and the third opening / closing valve when the operation of the fuel cell is stopped. Control means for closing the first to fourth opening / closing valves, wherein the first to fourth opening / closing valves are the first opening / closing valves when the first to fourth opening / closing valves are closed. The volume of hydrogen remaining between the valve and the second on-off valve and the third opening valve. When the volume of air remaining between the valve to the fourth on-off valve, in terms of the same pressure,
The mounting positions are set so that they are substantially equal or the volume of air becomes relatively small.

Further, in the fifth aspect of the invention, the solid polymer electrolyte fuel cell system which receives the supply of hydrogen and air to generate electric power is premised on the hydrogen supply system for supplying hydrogen to the fuel cell. A first on-off valve, a second on-off valve provided in a hydrogen recirculation system that returns hydrogen discharged from the fuel cell to the hydrogen supply system, and an air supply system that supplies air to the fuel cell. A third on-off valve, a pressure control valve provided in an exhaust system that discharges the reacted air discharged from the fuel cell to the outside of the system, and a first pressure sensor that detects the hydrogen side pressure of the fuel cell. A second pressure sensor for detecting an air side pressure of the fuel cell; first control means for closing the first to third opening / closing valves when the operation of the fuel cell is stopped; and the fuel cell When you stop driving
And a second control means for receiving the signals from the first and second pressure sensors and controlling the pressure regulating valve so that the hydrogen side pressure and the air side pressure of the fuel cell become substantially equal. is there.

[0011]

According to the first aspect of the invention, the reaction gas in the fuel cell is replaced with the inert gas when the operation of the fuel cell is stopped, so that the fuel cell immediately stops power generation. Therefore, a large pressure difference does not occur between the two electrodes of the fuel cell.

According to the second aspect of the invention, the air in the fuel cell is replaced with the reacted air when the operation of the fuel cell is stopped, so that the hydrogen remaining in the fuel cell is not completely consumed. When a small amount of oxygen contained in the reacted air is consumed, the fuel cell will stop generating electricity. Therefore, a large pressure difference does not occur between the two electrodes of the fuel cell.

According to the third invention, after the operation of the fuel cell is stopped, the equivalence ratios of hydrogen and oxygen that can be consumed by the fuel cell become almost equal, so that all of these reaction gases are consumed. Even if the power generation ends, the pressure drops at both poles are equal, so there is no large pressure difference between the poles.

According to the fourth aspect of the invention, after the operation of the fuel cell is stopped, the hydrogen equivalent and the oxygen equivalent that can be consumed by the fuel cell become substantially equal, so that these reaction gases are completely consumed. Even if the power generation ends, the pressure drops at both poles are equal, and therefore a large pressure difference does not occur between the poles.

According to the fifth aspect of the invention, after the operation of the fuel cell is stopped, even if there is a quantitative difference between hydrogen and air that can be consumed by the fuel cell, the reacted air is taken out of the system. The pressure is adjusted by the pressure adjusting valve provided in the discharging exhaust system so that the pressure difference between the two electrodes becomes substantially zero, so that a large pressure difference does not occur between the two electrodes. In a fuel cell that uses air as an oxidant, since the air contains a large amount of nitrogen, the pressure on the air side tends to be relatively higher than the pressure on the hydrogen side after the operation of the fuel cell is stopped. , Especially effective.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. First Embodiment (FIG. 1) FIG . 1 shows a fuel cell system A using oxygen as an oxidant.
In the figure, reference numeral 1 is a fuel cell for vehicle mounting, that is, for moving. The fuel cell 1 is composed of a low temperature operating type using a hydrogen ion conductor, that is, a solid oxide fuel cell operating at 100 ° C. or lower. The fuel cell 1 has ports 1a to 1f. Of these ports, the paired ports 1a and 1b are connected to the hydrogen gas system L1, hydrogen gas as a fuel is introduced from the port 1a, and excess hydrogen is supplied to the port 1b. Emitted from. Also, paired port 1
c and 1d are connected to the oxygen system L2, oxygen as an oxidant is introduced from the port 1c, and excess oxygen containing reaction water is discharged from the port 1d. In addition, the paired port 1e,
1f is connected to the temperature-controlled water circulation system L3, and pure water for cooling and humidification is introduced from the port 1e and discharged from the port 1f.

The hydrogen gas system L1 has a hydrogen storage alloy 2 as a hydrogen gas source. The hydrogen storage alloy 2 and the hydrogen introduction port 1a are connected to each other via a hydrogen supply pipe 4, and the supply pipe 4 extends from the hydrogen storage alloy 2 side toward the fuel cell 1 side.
A pressure reducing valve 5 and a solenoid type on-off valve 6 are provided in this order. The hydrogen discharge port 1b is connected to the
A check valve 10 is connected to the liquid separator 9, and a check valve 10 is provided in the discharge pipe 8. The check valve 10 prevents a backflow from the separator 9 side to the fuel cell 1 side. Further, the hydrogen gas system L1 is
It has a hydrogen reflux pipe 11 for returning the hydrogen gas separated by the separator 9 to the supply pipe 4. That is, the reflux pipe 11 has its upstream end connected to the separator 9 and its downstream end connected to the hydrogen supply pipe 4. More specifically, the downstream end of the return pipe 11 is connected to a portion of the supply pipe 4 downstream of the on-off valve 6,
A check valve 12 is interposed in the hydrogen reflux pipe 11, and the check valve 12 prohibits the backflow from the supply pipe 4 side to the separator 9. An exhaust pipe 13 is also connected to the hydrogen recirculation pipe 11, and the exhaust pipe 13 is provided with a solenoid type on-off valve 14 and a silencer 15.

The oxygen system L2 has an oxygen cylinder 16 as an oxygen gas source. Oxygen cylinder 16 and oxygen introduction port 1
c is connected via an oxygen supply pipe 17, and this supply pipe 1
7, from the oxygen cylinder 16 side toward the fuel cell 1 side,
A pressure reducing valve 18 and a solenoid type on-off valve 19 are provided in this order. The oxygen discharge port 1d is connected to the condenser 21 via the oxygen discharge pipe 20, and the excess oxygen discharged from the port 1d is removed by the condenser 21 from the water content (reaction product water of the fuel cell 1). . Also, oxygen system L2
Has an oxygen reflux pipe 22 for returning the oxygen separated by the condenser 21 to the oxygen supply pipe 17. That is, the oxygen reflux pipe 22
Has an upstream end connected to the condenser 21 and a downstream end connected to the oxygen supply pipe 17. More specifically, the downstream end of the oxygen return pipe 22 is connected to a portion of the supply pipe 17 on the downstream side of the opening / closing valve 19, and the oxygen return pipe 22 is provided with a check valve 23. By the stop valve 23, the supply pipe 1
Backflow from the 7 side to the separator 21 is prohibited. An exhaust pipe 24 is also connected to the oxygen recirculation pipe 22, and the exhaust pipe 24 is provided with a solenoid type on-off valve 25 and a silencer 26. On the other hand, the water separated in the condenser 21 is the pipe 2
It is stored in the water storage tank 28 through 7.

The temperature-controlled water circulation system L3 has a water supply pipe 29 connected to the water storage tank 28 and the water introduction port 1e, and a return pipe 30 connected to the water storage tank 28 and the drainage port 1f. In the water supply pipe 29, a pump 31, a three-way valve 32, and a radiator 33 are provided in this order from the water storage tank 28 toward the fuel cell 1, and the radiator 33 is provided with an electric fan 34. The water supply pipe 29 is also provided with a bypass pipe 35 that bypasses the radiator 33. The flow path of the temperature control water circulation system L3 is selectively changed to a mode of passing through the radiator 33 and a mode of bypassing the radiator 33 and passing through the bypass pipe 35 by switching the three-way valve 32, so that an appropriate temperature is obtained. The adjusted temperature-controlled water is supplied to the fuel cell 1 and used to adjust the temperature of the fuel cell 1 and humidify the reaction gas.

The fuel cell system A includes an inert gas system L4, and the inert gas system L4 has a cylinder 40 which stores an inert gas such as nitrogen gas. A common conduit 41 is connected to the inert gas cylinder 40, and the common conduit 41 is bifurcated into a first branch pipe 42 and a second branch pipe 43.
The first branch pipe 42 is connected to the oxygen system L2 (oxygen supply pipe 17), and the second branch pipe 43 is connected to the hydrogen system L1 (hydrogen supply pipe 4). More specifically, the first branch pipe 42 is connected to a portion immediately downstream of the on-off valve 19 in the oxygen system L2, and the second branch pipe 43 is connected to a portion immediately downstream of the on-off valve 6 in the hydrogen system L1. ing. The common conduit 41 described above is provided with a pressure reducing valve 45 and a solenoid type on-off valve 46. Further, check valves 47 and 48 are provided in the first branch pipe 42 and the second branch pipe 43, respectively, to prevent backflow from the oxygen system L2 and hydrogen system L1 sides toward the cylinder 40.

The fuel cell system A is integrally controlled by a control unit (not shown). To explain the content of the control in this embodiment, at the time of operation, the on-off valve 6 of the hydrogen system L1 and the on-off valve 19 of the oxygen system L2 are both opened to supply the reaction gas to the fuel cell 1. The power is generated. During this operation, the on-off valve 1 of the exhaust pipes 13 and 24
Both 4 and 25 are closed. On the other hand, when the operation of the fuel cell 1 is stopped, first, the reaction gas supply on-off valves 6 and 19 are both closed to stop the supply of the reaction gas to the fuel cell 1, and immediately thereafter the inert gas supply on-off valve 46 and The exhaust on-off valves 14 and 25 are opened for a fixed time.

By the above control, when the operation is stopped, the inert gas is supplied to the fuel cell 1 in place of the reaction gas, whereby the reaction gas remaining in the fuel cell 1 is replaced with the inert gas. become. Then, the reaction gas replaced with the inert gas is discharged to the outside of the system through the exhaust pipes 13 and 24. Thus, the fuel cell 1
Since the reaction gas therein is immediately replaced with the inert gas, the fuel cell 1 immediately stops its reaction, and the pressure drop in the fuel cell 1 due to the stop of operation can be prevented.

In the above-mentioned fuel cell system A, the inert gas is supplied to the hydrogen system L1 and the oxygen system L2 through the first and second branch pipes 42 and 43. The inert gas may be supplied to either the hydrogen system L1 or the oxygen system L2. When the inert gas is supplied only to the oxygen system L2, in other words, only the oxygen in the fuel cell 1 is supplied. When hydrogen is replaced with an inert gas, hydrogen, which is a fuel, is not released to the outside of the system through the exhaust pipe 13, which is economically advantageous.

Modification of First Embodiment In FIG. 1, a pressure sensor 50 is provided in the hydrogen gas system L1 at the downstream end of the hydrogen supply pipe 4, that is, in the vicinity of the fuel cell 1.
When the operation of the fuel cell 1 is stopped, first, as in the first embodiment, the reaction gas supply on-off valves 6 and 19 are both closed, and after the reaction by the residual gas is performed in the fuel cell 1 for a while, the pressure is reduced. When the pressure of the sensor 50 detects a predetermined pressure,
On-off valve for supplying inert gas 46 and on-off valve for exhausting 14,
25 may be opened for a certain period of time.

According to this control, by replacing the inside of the fuel cell 1 with the inert gas while reducing the amount of hydrogen gas released to the outside of the system, the pressure drop in the fuel cell 1 due to the stop of the operation can be prevented. Can be prevented. 2 and subsequent drawings,
Other embodiments of the present invention will be described. In these embodiments, the same elements as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. The features of each embodiment will be described below. The part will be explained.

Second Embodiment (FIG. 2) FIG. 2 schematically shows a fuel cell system B using air as an oxidant. The system B includes a hydrogen gas system L1, an air system L5, a temperature control water circulation system L3, and a reacted gas system L6. The hydrogen gas system L1 is the first except that it does not have the exhaust pipe 13, the on-off valve 14, and the silencer 15.
It has the same configuration as that of the embodiment.

The air system L5 has an air supply pipe 51 connected to the port 1c and an exhaust pipe 52 connected to the port 1d. In the air supply pipe 51, an air compressor 53, a pressure adjusting valve 54, and a pressure adjusting valve 54 in order from the upstream end toward the fuel cell 1.
A three-way valve 55 is provided, and the compressor 53 has an electric motor 56.
Driven by. On the other hand, in the exhaust pipe 52, the fuel cell 1
From the downstream end to the condenser 21 and the throttle 5 in that order.
7. A muffler 58 is provided, and excess air discharged from the port 1d is released to the atmosphere after removing the water content of the excess air by the condenser 21.

The reacted gas system L6 is a gas storage tank 60.
The tank 60 is connected with two pipes 62 and 63. The other end of the first pipe 62 is an air system L5.
Of the second pipe 63, and the other end of the second pipe 63 is connected to the exhaust pipe 52 of the air system L5. More specifically, the second pipe 63 is connected between the condenser 21 and the throttle 57 in the exhaust pipe 52, and a check valve 64 is interposed in the second pipe 63. As a result, part of the reacted air that has passed through the exhaust pipe 52 is sent to the tank 60 through the second pipe 63 and is stored in this tank 60. From the tank 60 side by the check valve 64, Backflow to the exhaust pipe 52 is prohibited.

The fuel cell system B is integrally controlled by a control unit (not shown). The contents of the control in this embodiment will be described. During operation, the opening / closing valve 6 of the hydrogen system L1 is opened to supply hydrogen gas to the fuel cell 1. Further, the air system L5 is controlled by the three-way valve 55.
A path that connects the air compressor 53 and the fuel cell 1 is opened to supply pressurized air to the fuel cell 1, whereby the fuel cell 1 generates electricity. A part of the reacted air discharged from the fuel cell 1 (port 1d) is in the second pipe 63.
And stored in the tank 60. On the other hand, fuel cell 1
When the operation is stopped, the opening / closing valve 6 of the hydrogen system L1 is closed and the supply of hydrogen gas to the fuel cell 1 is stopped.
Further, in the air system L5, the three-way valve 55 is switched to close the path for communicating the air compressor 53 with the fuel cell 1, and open the path for communicating the tank 60 with the fuel cell 1.

By the above control, when the operation is stopped, the reacted air is supplied to the fuel cell 1 instead of the air, whereby the air remaining in the fuel cell 1 is replaced with the reacted air. Become. As a result, when the small amount of oxygen contained in the reacted air is completely consumed, the fuel cell 1 does not completely consume all the hydrogen remaining in the fuel cell 1.
Stops its power generation. Therefore, it becomes possible to suppress the pressure drop in the fuel cell 1, and it is possible to prevent the performance deterioration of the electrolyte layer due to this pressure drop. When the operation is stopped, the air remaining in the fuel cell 1 may be replaced with the reacted air, and then the throttle 57 may be closed to keep the pressure in the fuel cell 1 constant.

Third Embodiment (FIG. 3) FIG. 3 uses oxygen as an oxidant, similarly to the fuel cell system A of the first embodiment (FIG. 1). Basically, FIG. In the system A of the present embodiment, the hydrogen system L1 has a solenoid type opening / closing valve 6 of the hydrogen supply pipe 4 and a solenoid type opening / closing of the hydrogen discharge pipe 8 in the system A shown in FIG. A valve 67 is attached, and in addition to the solenoid type opening / closing valve 19 of the oxygen supply pipe 17, the oxygen system L2 is
A solenoid type on-off valve 68 is attached to the oxygen discharge pipe 20. The mounting positions of these on-off valves 6, 19, 67, 68 will be described. In the pipeline (including the hydrogen gas passage in the fuel cell 1) from the supply-side on-off valve 6 to the discharge-side on-off valve 67 of the hydrogen system L1. The equivalent of the hydrogen gas contained is equal to the equivalent of the oxygen gas contained in the pipeline (including the oxygen gas passage in the fuel cell 1) from the supply side opening / closing valve 19 to the discharge side opening / closing valve 68 of the oxygen system L2. On-off valve 6,
19, 67, 68 are attached.

For example, when the hydrogen supply pressure and the oxygen supply pressure are equal, the volume of the pipeline (including the hydrogen gas passage in the fuel cell 1) from the supply side opening / closing valve 6 to the discharge side opening / closing valve 67 of the hydrogen system L1 and V _1, the relationship between the volume V ₂ of the pipe from the supply-side valve 19 of the oxygen-based L2 to the discharge side valve 68 (including oxygen gas passage in the fuel cell 1) is approximately V ₁ = 2xV
The mounting position of the on-off valve is set so that it becomes ₂ .

To explain the content of the control in this embodiment, during operation, both the supply side opening / closing valve 6 and the discharge side opening / closing valve 67 of the hydrogen system L1 are opened to supply hydrogen gas to the fuel cell 1. Be seen. Further, both the supply side opening / closing valve 19 and the discharge side opening / closing valve 68 of the oxygen system L2 are opened to supply the oxygen gas to the fuel cell 1, and the fuel cell 1 receives the reaction gas and Generate electricity. During this operation, the open / close valves 14 and 25 of the exhaust pipes 13 and 24 are both closed. On the other hand, when the operation of the fuel cell 1 is stopped, first, the reaction gas supply on-off valves 6 and 19 and the discharge side on-off valves 67 and 68 are simultaneously closed to stop the supply of the reaction gas to the fuel cell 1.

With the above control, when the operation is stopped, power is generated by the residual gas in the fuel cell 1 and the reaction gas is consumed, but from the supply side opening / closing valve 6 to the discharge side opening / closing valve 67 of the hydrogen system L1. Since the equivalent of hydrogen gas contained in the pipeline is twice the equivalent of the oxygen gas contained in the pipeline from the supply side opening / closing valve 19 to the discharge side opening / closing valve 68 of the oxygen system L2,
Both electrodes in the fuel cell 1 will have an equal pressure drop,
Therefore, no pressure difference is generated between the two electrodes in the fuel cell 1 when the operation of the fuel cell 1 is stopped.

Fourth Embodiment (FIG. 4) FIG. 4 uses air as an oxidant as in the fuel cell system B of the second embodiment (FIG. 2). The configuration is basically the same as that of the system B shown in FIG. 2 except that the reacted gas system L6 does not exist.

In the system B of the present embodiment, in the hydrogen system L1, a solenoid type opening / closing valve 6 is attached to the hydrogen discharge pipe 8 in addition to the solenoid type opening / closing valve 6 of the hydrogen supply pipe 4. Further, in the air system L5, a solenoid type on-off valve 70 is attached to the air supply pipe 51, and a solenoid type on-off valve 71 is attached to the air discharge pipe 52. The mounting positions of the on-off valves 6, 69, 70, 71 will be described. For example, when the hydrogen supply pressure is equal to the air supply pressure, from the supply side on-off valve 6 to the discharge side on-off valve 67 of the hydrogen system L1. V ₁ of the pipeline (including the hydrogen gas passage in the fuel cell 1) and the pipeline from the supply side opening / closing valve 19 to the discharge side opening / closing valve 68 of the air system L2 (including the air passage in the fuel cell 1) The mounting positions of the on-off valves 6, 69, 70 and 71 are set so that the volume V _{2 of the above} ) becomes substantially equal.

The contents of the control in this embodiment will be described. During operation, both the supply side opening / closing valve 6 and the discharge side opening / closing valve 69 of the hydrogen system L1 are opened to supply hydrogen gas to the fuel cell 1. Be seen. Further, both the supply side opening / closing valve 70 and the discharge side opening / closing valve 71 of the air system L2 are opened to supply air to the fuel cell 1, and the fuel cell 1 receives supply of these reaction gases, The power is generated. On the other hand,
When the operation of the fuel cell 1 is stopped, the on-off valves 6 and 70 for supplying the reaction gas and the on-off valves 69 and 71 on the discharge side are simultaneously closed to stop the supply of the reaction gas to the fuel cell 1.

According to the above control, when the operation is stopped, power is generated by the residual gas in the fuel cell 1 and the reaction gas is consumed. However, from the supply side opening / closing valve 6 to the discharge side opening / closing valve 67 of the hydrogen system L1. Compared with the equivalent amount of hydrogen gas contained in the pipeline, from the supply side opening / closing valve 19 to the discharge side opening / closing valve 6 of the air system L2.
Since the equivalent amount of oxygen contained in the air in the pipelines up to 8 is small, the fuel cell 1 stops power generation when the oxygen in the residual air is exhausted. In the state where the power generation is stopped, the residual hydrogen remains, so that an extreme pressure difference does not occur between both electrodes in the fuel cell 1.

Modifications of Second and Fourth Embodiments As shown in FIGS. 2 and 4, a first pressure sensor 73 is provided at the downstream end of the hydrogen supply pipe 4, and an air supply pipe 51 is provided.
The second pressure sensor 74 is provided at the downstream end of the fuel cell 1
When the operation is stopped, the first and second pressure sensors 73,
The output signal of 74, that is, the hydrogen side pressure and the air side pressure are compared, and when the difference between these pressures becomes larger than a predetermined value, in the second embodiment, the throttle 57 is opened appropriately and the In the fourth embodiment, the air discharge side opening / closing valve 7
1 and the throttle 57 may be opened appropriately so that the pressure difference between both electrodes in the fuel cell 1 becomes substantially zero.

[0040]

As is apparent from the above description, according to the present invention, in any of the first to fifth inventions, a large pressure difference occurs between both electrodes after the operation of the fuel cell is stopped. Can be suppressed. Therefore, the performance deterioration of the electrolyte due to the pressure difference between the two electrodes can be prevented.

[Brief description of drawings]

FIG. 1 is a system diagram schematically showing an entire solid polymer electrolyte fuel cell system that receives hydrogen and oxygen to generate electric power, and is an overall configuration diagram of a first embodiment.

FIG. 2 is a system diagram schematically showing an entire solid polymer electrolyte fuel cell system that receives hydrogen and air to generate electric power, and is an overall configuration diagram of a second embodiment.

FIG. 3 is a system diagram schematically showing an entire solid polymer electrolyte fuel cell system that receives hydrogen and oxygen to generate electric power, and is an overall configuration diagram of a third embodiment.

FIG. 4 is a systematic diagram schematically showing an entire solid polymer electrolyte fuel cell system that receives supply of hydrogen and air to generate electricity, and is an overall configuration diagram of a fourth embodiment.

[Explanation of symbols]

 1 Fuel cell L1 Hydrogen gas system L2 Oxygen system L4 Inert gas system L5 Air system L6 Reacted gas system 6 Hydrogen supply side opening / closing valve 11 Hydrogen exhaust pipe provided in hydrogen recirculation pipe 14 Opening valve provided in hydrogen exhaust pipe 16 Oxygen cylinder 19 Oxygen supply side opening / closing valve 24 Oxygen exhaust pipe provided in oxygen recirculation pipe 25 Opening / closing valve provided in oxygen exhaust pipe 40 Inert gas cylinder 46 Opening / closing valve provided in inert gas system 53 Air compressor 55 3 Square valve 57 Throttle 60 Tank for storing reacted air 67 On-off valve provided on hydrogen discharge side 68 On-off valve provided on oxygen discharge side 69 On-off valve provided on hydrogen discharge side 71 Provided on air discharge side Open / close valve 73 Sensor for detecting hydrogen side pressure 74 Sensor for detecting air side pressure

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiro Kiriki 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Motor Corporation

Claims (5)

[Claims] 1. A solid polymer electrolyte fuel cell system for generating electric power by supplying a reaction gas composed of hydrogen and oxygen, wherein the reaction gas supply system of the fuel cell is provided to supply the reaction gas to the fuel cell. A first on-off valve that opens and closes, a second on-off valve that is provided in an exhaust pipe that discharges excess reaction gas discharged from the fuel cell to the outside of the system, and an inert gas that is attached to the reaction gas supply system of the fuel cell. Source, a third opening / closing valve for opening and closing the supply of the inert gas stored in the inert gas source to the fuel cell, and a valve for closing the first opening / closing valve when the operation of the fuel cell is stopped A control device for a fuel cell system, which further comprises control means for opening the second on-off valve and the third on-off valve for a predetermined time to replace the reaction gas in the fuel cell with an inert gas. 2. A solid polymer electrolyte fuel cell system for generating power by receiving supply of hydrogen and air, comprising: a first opening / closing valve provided in an air supply system of the fuel cell to open / close supply of air to the fuel cell. A storage unit attached to the air supply system of the fuel cell for storing the reacted air discharged from the fuel cell; and a second opening and closing unit for supplying the reacted air stored in the storage unit to the fuel cell. An on-off valve, and a control for closing the first on-off valve and closing the second on-off valve when the operation of the fuel cell is stopped to replace the reaction gas in the fuel cell with the reacted air. And a control device for the fuel cell system. 3. A solid polymer electrolyte fuel cell system for generating electric power by supplying hydrogen and oxygen, wherein the first is provided in a hydrogen supply system for supplying hydrogen to the fuel cell.
An on-off valve, a second on-off valve provided in a hydrogen recirculation system for returning hydrogen discharged from the fuel cell to the hydrogen supply system, and a second on-off valve provided in an oxygen supply system for supplying oxygen to the fuel cell. An opening / closing valve of No. 3, a fourth opening / closing valve provided in an oxygen recirculation system for returning oxygen discharged from the fuel cell to the oxygen supply system, and the first to the third valves when stopping the operation of the fuel cell. A control means for closing a fourth on-off valve, wherein the first to fourth on-off valves are controlled from the first on-off valve when the first to fourth on-off valves are closed. The second
The mounting position is set so that the hydrogen equivalent remaining up to the opening / closing valve of the above and the oxygen equivalent remaining between the third opening / closing valve and the fourth opening / closing valve become substantially equal. A control device for a fuel cell system, characterized in that 4. A solid polymer electrolyte fuel cell system for generating electric power by supplying hydrogen and air, wherein the first is provided in a hydrogen supply system for supplying hydrogen to the fuel cell.
An on-off valve, a second on-off valve provided in a hydrogen recirculation system for returning hydrogen discharged from the fuel cell to the hydrogen supply system, and a second on-off valve provided in an air supply system for supplying air to the fuel cell. 3, an on-off valve of No. 3, a fourth on-off valve provided in an exhaust system for discharging the reacted air discharged from the fuel cell to the outside of the system, and the first to the third valves when stopping the operation of the fuel cell. A control means for closing a fourth on-off valve, wherein the first to fourth on-off valves are controlled from the first on-off valve when the first to fourth on-off valves are closed. The second
The volume of hydrogen remaining up to the opening / closing valve and the volume of air remaining between the third opening / closing valve and the fourth opening / closing valve are substantially equal when converted to the same pressure, or A control device for a fuel cell system, wherein the mounting position is set so that the volume of air becomes relatively small. 5. A solid polymer electrolyte fuel cell system for generating electric power by supplying hydrogen and air, wherein the first is provided in a hydrogen supply system for supplying hydrogen to the fuel cell.
An on-off valve, a second on-off valve provided in a hydrogen recirculation system for returning hydrogen discharged from the fuel cell to the hydrogen supply system, and a second on-off valve provided in an air supply system for supplying air to the fuel cell. An on-off valve of No. 3, a pressure control valve provided in an exhaust system that discharges the reacted air discharged from the fuel cell to the outside of the system, a first pressure sensor that detects the hydrogen side pressure of the fuel cell, A second pressure sensor for detecting an air side pressure of the fuel cell; a first control means for closing the first to third opening / closing valves when the operation of the fuel cell is stopped; and an operation of the fuel cell Second control for receiving the signals from the first and second pressure sensors and controlling the pressure adjusting valve so that the hydrogen side pressure and the air side pressure of the fuel cell become substantially equal when the fuel cell is stopped. For controlling a fuel cell system having means .