JP2009151973A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system realizing compact arrangement of a fuel cell stack and peripheral equipment such as a dilution device. <P>SOLUTION: In a fuel cell system 2, hydrogen gas supplied from a hydrogen tank 16 through a valve 19 is passed through high insulating piping 31, and supplied to a fuel cell stack 12. Similarly, air containing oxygen gas, by supplying air taking in from an air filter 15 with a pump 14 to a humidifier 13 through high insulating piping 32, is supplied to the fuel cell stack 12 from the humidifier 13. Hydrogen offgas after electrochemical reaction exhausted from the fuel cell stack 12 is exhausted to a retention chamber 21 of a dilution device 20 through the high insulation piping. Similarly air offgas after electrochemical reaction exhausted from the fuel cell stack 12 is passed through high insulation piping 34 and the humidifier 13 and then exhausted to a dilution chamber 22 of the dilution device 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell system in which a diluter is housed in the same case as a fuel cell stack.

  There is a fuel cell mounted electric vehicle (hereinafter referred to as a vehicle) in which a fuel cell is mounted as a power source of the electric vehicle. The fuel cell mounted on this vehicle has an ion exchangeable electrolyte membrane, a hydrogen electrode disposed on one surface of the electrolyte membrane, an oxygen electrode disposed on the other surface, and hydrogen gas on each electrode. And a separator that forms a flow path for supplying air, and a plurality of the cells are stacked to form a fuel cell stack.

  A fuel cell system including such a fuel cell stack generates power from hydrogen as fuel and oxygen in the air, and when hydrogen gas supplied to the hydrogen electrode of the fuel cell is hydrogen ionized by an electrochemical reaction. Electrons moving from the hydrogen electrode to the oxygen electrode can be taken out as a direct current by an external circuit.

  In the conventional fuel cell stack, the hydrogen gas supplied to the electrolyte membrane cannot be completely reacted, and a part of the hydrogen gas supplied to the hydrogen electrode is discharged from the fuel cell stack in an unreacted state. For this reason, a circulation system is provided in which the unreacted off-gas is returned to the fuel cell stack and used effectively.

  The off gas circulating in the circulation system includes hydrogen gas and reaction water circulating in the fuel cell stack. The hydrogen gas and reaction water contain trace amounts of impurities dissolved from the fuel cell stack and piping parts. Impurities may also enter from the air sucked from outside air and pass through the electrolyte membrane and enter the hydrogen gas circulation system.

  Therefore, in Patent Document 1, high insulation is provided between the supply side and the exhaust side of the fuel cell stack, the residual moisture is determined based on the insulation resistance during operation of the fuel cell stack, and the moisture that needs to be removed is the fuel cell. A technique for determining whether or not it remains in the stack and discharging reaction water is disclosed.

  Further, in the fuel cell system of Patent Document 2, the off gas is discharged as necessary, the reaction water and impurities accumulated together with the off gas are discharged, diluted with the off gas from the oxygen electrode, and the hydrogen concentration is reduced to the rear of the vehicle. Techniques relating to exhaust means for discharging are disclosed. In addition, this fuel cell system is compact in that the fuel cell stack, temperature adjusting means, humidifying means, reformer and diluter are housed in the same case in order to arrange the fuel cell stack and its peripheral devices in a compact manner. We are trying to make it.

JP 2006-221987 JP 2004-168101 A

  However, in the fuel cell system disclosed in Patent Document 1, even if a high insulation is maintained between the fuel cell stack and the pipe, a means for preventing leakage is separately provided by providing an electric circuit for measuring the insulation resistance. It is necessary to provide it.

  Moreover, even when housed in the same case as disclosed in Patent Document 2, the amount of heat for warm-up is large due to the increase in capacity due to the connection pipe and the diluter that ensure insulation between the fuel cell system and peripheral devices. In particular, the reaction water discharged at a temperature below freezing point may freeze inside and block the flow path.

  Furthermore, in the conventional fuel cell system, since many unreacted fuel gases are included in the off-gas discharged from the fuel cell stack, it is necessary to provide a circulation system for circulating the unreacted fuel gases to the fuel gas supply channel. In addition, in order to secure the dilution performance of the hydrogen gas diluter, it is necessary to secure the required capacity, but the power generation performance of the fuel cell stack may be sacrificed due to the mounting space.

  In order to solve such problems, the present invention provides a fuel cell system in which peripheral devices such as a fuel cell stack and a diluter are arranged in a compact manner.

  In order to achieve the above object, the fuel cell system according to the present invention is a fuel cell system in which the diluter is housed in the same case as the fuel cell stack, and the diluter is formed of a highly insulating resin. It is characterized by.

  In the fuel cell system according to the present invention, the air pipe and the hydrogen pipe of the diluter disposed in the exhaust passage of the fuel cell stack are formed of a highly insulating resin.

  Further, in the fuel cell system according to the present invention, the openings of the air piping and the hydrogen piping inside the diluter are provided to be separated from the inner wall and the insulating wall in consideration of the insulating property of the reaction water discharged from the fuel cell stack. It is characterized by that.

  Further, in the fuel cell system according to the present invention, the diluter causes the hydrogen gas discharged from the fuel cell stack to stay, and the air discharged from the fuel cell stack to flow in. A dilution chamber that mixes and dilutes the hydrogen gas, and is characterized in that a highly insulating air pipe and an opening of the hydrogen pipe are arranged so as to protrude into the interior of each chamber.

  Furthermore, in the fuel cell system according to the present invention, the inside of the diluter is prevented from freezing by using a low heat radiation resin that is housed in the same case as the fuel cell stack and has a lower heat release rate than the metal pipe. And

  By using the fuel cell system according to the present invention, the pipe inside the diluter is a highly insulating pipe, so there is no need to connect a separate pipe having the function of electrical insulation outside, reducing the number of parts, There is an effect that the piping distance can be shortened.

  Further, by using the diluter of the fuel cell system according to the present invention, there is no increase in the capacity of the connecting pipe that secures insulation between the fuel cell system and peripheral devices. Has the effect of preventing freezing of the product water.

Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.
(Example)

  FIG. 1 shows a configuration of a fuel cell-mounted electric vehicle (hereinafter referred to as a vehicle) equipped with a fuel cell system 2. The fuel cell system 2 is arranged in the vehicle in consideration of the weight distribution of the vehicle. A fuel cell case 10 in which a fuel cell stack 12 and the like are stored, an air filter 15, and a pump 14 are disposed in the front portion of the vehicle 1. And a hydrogen tank 16 and a muffler 17 are mounted on the rear part. Further, the fuel cell case 10 is provided with temperature control means 11 for cooling and keeping the temperature of the fuel cell system 2, a fuel cell stack 12, a humidifier 13, and a diluter 20. In FIG. 1, one of the characteristic features of this embodiment is that the hydrogen off-gas discharged from the fuel cell stack 12 is sent directly to the diluter 20 and does not have a conventional hydrogen off-gas circulation system. .

  FIG. 5 shows the difference between the diluter capacity in the conventional fuel cell system and the diluter capacity according to this embodiment. Generally, unreacted hydrogen gas is included in the off-gas discharged from the fuel cell system. As shown in the conventional example in the figure, the unreacted hydrogen gas increases as the extracted current increases. When a large amount of unreacted hydrogen gas is generated in this way, the power generation efficiency and fuel consumption are reduced. Therefore, a general fuel cell system is provided with a circulation system for circulating the unreacted hydrogen gas to the fuel gas supply channel.

  In contrast, in the fuel cell system according to the present embodiment, as shown in the present embodiment of FIG. 5, the fuel cell stack is improved to reduce the generation of unreacted hydrogen gas. By reducing the generation of unreacted hydrogen gas, it has become possible to eliminate the circulation system of unreacted hydrogen gas, which has been conventionally required, and to reduce the capacity of the diluter.

  As described above, one of the characteristic features of the present embodiment is that the amount of unreacted hydrogen gas is reduced, the diluter is downsized, and the diluter is housed in the fuel cell case, so that the heat with the fuel cell stack is reduced. It is easy to exchange. Furthermore, in this embodiment, for further miniaturization, a pipe is protruded inside the fuel cell case to achieve high insulation.

  FIG. 2 is a configuration diagram showing the configuration of the fuel cell system 2. In this fuel cell system 2, the fuel cell stack 12, the humidifier 13, the diluter 20, and the temperature control means 11 are arranged inside the fuel cell case 10 to facilitate temperature adjustment.

  Next, the flow of hydrogen gas as fuel will be shown. Hydrogen gas supplied from the hydrogen tank 16 through the valve 19 passes through the highly insulating pipe 31 and is supplied to the fuel cell stack 12. Similarly, the air containing oxygen gas is supplied from the air filter 15 by the pump 14 to the humidifier 13 through the highly insulating pipe 32 and is further supplied from the humidifier 13 to the fuel cell stack 12. . These fuel gases cause an electrochemical reaction in the fuel cell stack 12.

  The hydrogen off-gas after the electrochemical reaction discharged from the fuel cell stack 12 is discharged to the retention chamber 21 of the diluter 20 through the highly insulating pipe. Similarly, the air off-gas after the electrochemical reaction discharged from the fuel cell stack 12 passes through the highly insulating pipe 34 and the humidifier 13 and is discharged to the dilution chamber 22 of the diluter 20. In the diluter 20, the hydrogen off gas from the residence chamber is diluted with the air off gas in the dilution chamber 22, and the diluted hydrogen off gas is discharged from the exhaust pipe 35. Similarly, the reaction water by the electrochemical reaction that has flowed into the dilution chamber 22 is drained from the drain pipe 36.

  FIG. 3 shows the structure of the diluter 20 in the fuel cell system. The diluter 20 is divided into flow plates 23, 24, and 25 provided with a plurality of holes, a staying chamber 21 and a dilution chamber 22 by the flow plates 23, and divided into a plurality of rooms by the flow plates 24 and 25. It has a dilution chamber 22, a highly insulating pipe 33 to which hydrogen off gas is supplied, a highly insulating pipe 34 to which air off gas is supplied, an exhaust pipe 35, and a drain pipe 36.

  The exhaust port 35 is provided with a backfire prevention filter 41 or a wire mesh as flame control means. A similar flame control means is also provided in the openings of the highly insulating pipes 33 and 34.

  FIG. 4 shows the insulation distance of the diluter, and FIG. 4A shows the insulation distance d1 between the flow plate 23 where the reaction water stays, the high insulation pipe 33 and the high insulation pipe 34. ing. Similarly, FIG. 4B shows an insulation distance d2 between the wall surface of the diluter 20 and the openings of the highly insulating pipes 33 and 34, and an insulation distance d3 between the highly insulating pipe 33 and the flow plate 24. ing. By securing these insulation distances, for example, an insulation resistance of about several megaohms to several tens of megaohms is realized.

  In the present embodiment, the retention chamber 21 and the dilution chamber 22 forming the diluter 20 are configured to easily retain heat generated from the fuel cell stack using a low heat dissipation resin having a low heat dissipation rate. For this reason, in this embodiment, although the material of the highly insulating piping 33 and 34 and the diluter main body is different, it is not limited to this form, and has both high insulation and low heat dissipation. It may be integrally molded with resin.

  Conventionally, piping having an electrical insulation function was used for connection between the fuel cell stack and the diluter, but in this embodiment, the piping inside the diluter is made as a highly insulating piping, so that electrical insulation is provided outside. This eliminates the need to connect a separate pipe having the above function, thereby reducing the number of parts and the pipe distance.

  As described above, by using the diluter of the fuel cell system according to the present embodiment, the connection piping that secures insulation between the fuel cell system and peripheral devices is not used, so that there is no increase in capacity due to the connection piping. Thus, it is possible to prevent the generated water from freezing below the freezing point without increasing the amount of heat for warming up. Further, the assembly can be facilitated by reducing the number of parts, and the cost of products and manufacturing can be reduced.

It is a block diagram which shows the structure of the fuel cell mounting type electric vehicle carrying the fuel cell system which concerns on this embodiment. It is a block diagram which shows the structure of the fuel cell system which concerns on this embodiment. It is a perspective view explaining the structure of the diluter in a fuel cell system. It is explanatory drawing explaining the insulation distance of a diluter. It is explanatory drawing explaining the difference between the conventional dilution machine capacity | capacitance and the dilution machine capacity | capacitance which concerns on this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Vehicle, 2 Fuel cell system, 10 Fuel cell case, 11 Temperature control means, 12 Fuel cell stack, 13 Humidifier, 14 Pump, 15 Air filter, 16 Hydrogen tank, 17 Muffler, 19 Valve, 20 Diluter, 21 Stay Chamber, 22 Dilution chamber, 23, 24, 25 Flow plate, 31, 32, 33, 34 Highly insulating piping, 35 Exhaust pipe, 36 Drain pipe, 41 Backfire prevention filter.

Claims (5)

In the fuel cell system in which the diluter is housed in the same case as the fuel cell stack,
A fuel cell system, wherein a diluter is formed of a highly insulating resin. The fuel cell system according to claim 1,
A fuel cell system, wherein an air pipe and a hydrogen pipe of a diluter disposed in an exhaust passage of a fuel cell stack are formed of a highly insulating resin. The fuel cell system according to claim 1 or 2,
An opening of the air pipe and the hydrogen pipe inside the diluter is provided with an inner wall and a space apart from each other in consideration of insulation of the reaction water discharged from the fuel cell stack. The fuel cell system according to any one of claims 1 to 3,
The diluter
A retention chamber for retaining hydrogen gas discharged from the fuel cell stack;
A dilution chamber for introducing air discharged from the fuel cell stack and diluting the air with hydrogen gas from the residence chamber; and
Have
A fuel cell system, wherein openings of high-insulation air pipes and hydrogen pipes are arranged so as to protrude into the respective chambers. The fuel cell system according to any one of claims 1 to 4,
A fuel cell system characterized in that the inside of the diluter is prevented from freezing by using a low thermal radiation resin that is housed in the same case as the fuel cell stack and has a lower heat release rate than that of metal piping.

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