JP4505712B2 - Fuel tank for direct methanol fuel cell and direct methanol fuel cell system using the same - Google Patents

Description

  The present invention relates to a fuel tank for storing and supplying methanol, which is a liquid fuel, in a direct methanol fuel cell system, for example, and further relates to a fuel cell system including such a fuel tank.

  A fuel cell is a power generation device that generates power by electrochemically reacting a fuel fluid such as hydrogen gas or methanol with an oxidizing fluid (oxygen contained in air). For example, in the case of a solid polymer type fuel cell, each power generator portion has a structure in which an electrolyte membrane made of a solid polymer is sandwiched between an oxygen side electrode and a fuel side electrode. Air is supplied to supply the fuel, fuel fluid is supplied to the fuel side electrode, and power generation is performed by the electrochemical reaction.

  During power generation, in a polymer electrolyte fuel cell, ions (protons) move through an electrolyte membrane that is an ion exchange membrane and functions as a proton conductor membrane, and reacts with oxygen on the oxygen side electrode to generate a current. At the same time, water is generated at the oxygen side electrode. The power generator part of a fuel cell is called an electrolyte membrane / electrode assembly or MEA (Membrane and Electrode Assembly), and this electrolyte membrane / electrode assembly is a separator in which a fuel fluid channel and an air channel are formed. A fuel cell having a stacked structure (stacked structure) is configured by stacking a plurality of power generation cells.

  The above-described fuel cell has been attracting attention in recent years as a clean power source in which the product generated by power generation is water and does not pollute the environment. For example, in a large system such as an electric vehicle or a residential power system While it is expected to be put to practical use, taking advantage of the small size and light weight of the polymer electrolyte fuel cell, its application as a power source for portable electronic devices such as notebook personal computers is also being studied.

  By the way, in a fuel cell used for such a portable electronic device or the like, a direct methanol fuel cell system using methanol as a fuel, which is easier to handle than hydrogen gas, is considered advantageous. In this direct methanol fuel cell system, the fuel tank attached to the electronic device is removed, and the fuel methanol is replenished. Then, the fuel cell system is attached to the electronic device again and the methanol in the fuel tank is supplied to the fuel cell. Power generation is performed.

Therefore, a fuel tank having a structure in which internal methanol is pushed out by an elastic membrane has been proposed (see, for example, Patent Document 1 and Patent Document 2). In this Patent Document 1, a stretchable elastic membrane is set in a container, and liquid fuel is stored in the membrane, whereby the liquid fuel is discharged without using other energy by using the tension of the elastic membrane. A fuel tank is disclosed. In Patent Document 2, a partition made of a polymer material composed of an alkene monomer or an alkagen monomer is provided in a tank, fuel is stored inside, and a water absorbing material is stored outside, thereby absorbing water. There is disclosed a fuel tank in which fuel is supplied by applying pressure to a partition wall using a pressure when the material expands by taking in generated water.
Japanese Patent Laid-Open No. 4-223058 JP 2003-92128 A

  However, the elastic membranes and partition walls used in the inventions described in these patent documents have a certain degree of permeability to the liquid fuel, and when liquid fuel such as methanol is directly stored therein, the outer surface thereof is stored. May be lost little by little due to transpiration.

The present invention has been proposed in order to eliminate such drawbacks of the prior art, and enables smooth fuel supply by the self-shrinking force, while preventing liquid fuel from evaporating and reducing liquid fuel loss. It aims at providing the fuel tank for direct methanol type fuel cells which can be minimized, and also aims at providing a direct methanol type fuel cell system.

A fuel tank for a direct methanol fuel cell according to the present invention is a fuel tank in which an interior container that contains liquid fuel is provided in an exterior container. The interior container includes a partition wall made of a fluorine-based resin, and an expansion and contraction that wraps outside the partition wall. It is composed of a sexual member has a double structure, the outer container is mounted in a holder in the form of being sandwiched by the quick connector, the holder opening of the inner container is attached to Rutotomoni, holder, the interior container The liquid fuel circulation pipe in which a plurality of liquid fuel circulation holes through which liquid fuel is circulated is formed on the outer periphery is provided.
Further, a direct methanol fuel cell system of the present invention, a fuel cell, which includes a fuel tank for a direct methanol fuel cell supplies the liquid fuel is a fuel to the fuel cell, as the fuel tank, the Each is provided with a fuel tank for a direct methanol fuel cell .

In the fuel tank for a direct methanol fuel cell according to the present invention, an internal container for storing a liquid fuel such as methanol has a double structure, and a partition made of a fluorine-based resin is arranged at a portion in direct contact with methanol. The fluororesin has little permeability to liquid fuel such as methanol.
In addition, since the outer side of the partition wall is encased by a stretchable member, stretchability is imparted when viewed from the whole interior container, and the liquid fuel contained in the partition wall is pushed out by the contraction force of the stretchable member. Smooth fuel supply is realized.
In addition, by providing a liquid fuel circulation pipe having a large number of liquid fuel circulation holes in the interior container, even if the remaining amount of liquid fuel is small, it can be sucked out with a small suction force .

  According to the present invention, since the partition wall for storing the liquid fuel is formed of the fluororesin, transpiration due to permeation of the liquid fuel such as methanol can be reduced. Therefore, not only can an economic effect be obtained, it is also advantageous in terms of safety. Further, according to the present invention, since the stretchability is imparted to the interior container in which the liquid fuel is accommodated by the stretchable member, the fuel can be smoothly supplied by the contraction force. In particular, by combining with a fuel supply pump on the fuel cell system side, liquid fuel can be quickly discharged from the fuel tank and supplied to the fuel cell.

  Hereinafter, embodiments of a fuel tank and a fuel cell system to which the present invention is applied will be described with reference to the drawings.

  FIG. 1 shows an example of a fuel tank to which the present invention is applied. A fuel tank 1 shown in FIG. 1 is composed of an outer container 2 and an inner container 3 and has a double structure. The exterior container 2 is formed of a material having rigidity, for example, a resin such as polyethylene. The outer container 2 is not limited to this, and can be formed of any material, but it is preferable to form the outer container 2 with a material having rigidity in consideration of handleability, equipment mounting property, and the like. The outer container 2 is provided with air holes 2a for the purpose of eliminating the negative pressure when the inner container 3 contracts.

  The interior container 3 itself has a double structure, and is composed of an inner partition wall 4 and a balloon 5 that is a stretchable member that wraps the outside. Therefore, the entire interior container 3 exhibits elasticity by the action of the balloon 5.

  In the interior container 3, liquid fuel such as methanol is accommodated and stored in the inner partition wall 4. That is, the partition 4 is in direct contact with the liquid fuel. Here, the partition walls 4 are made of, for example, a fluorine-based resin such as a low-permeability ethylene tetrafluoride / perfluoroalkoxyethylene copolymer resin (PFA).

  The partition wall 4 has a size corresponding to the outer container 2. That is, the maximum inner volume of the partition wall 4 is equal to or greater than the inner volume of the outer container 2, and when the partition wall 4 is filled with liquid fuel, the partition wall 4 has an inner peripheral surface of the outer container 2. It can be expanded until it adheres to. Therefore, it is possible to ensure a capacity corresponding to the size of the outer container 2.

  On the other hand, since the balloon 5 is not in direct contact with the liquid fuel, it is not necessary to consider the permeability of the liquid fuel, and a material having elasticity can be arbitrarily selected and used. For example, latex rubber or the like Can be used. The balloon 5 also has a size that can be expanded until it comes into close contact with the inner peripheral surface of the outer container 2, and does not hinder the capacity of liquid fuel that can be stored in the inner container 3.

  As described above, in the fuel tank 1 of the present embodiment, in the interior container 3, the fluorocarbon resin having a low liquid fuel permeability is used for the partition wall 4 to suppress the transpiration of the liquid fuel, and the outer balloon 5 wraps it. Thus, pressure is applied to the liquid fuel in the partition wall 4 by the tension generated in the balloon 5 when the partition wall 4 is filled with liquid fuel, and the discharge is promoted.

  At this time, in order to adjust the tension applied by the balloon 5 and maintain the adhesion to the partition wall 4, the balloon 5 is formed with a large number of air vent holes 5a as shown in FIG. By increasing the size or increasing the number of the air vent holes 5a, the tension of the balloon 5 gradually decreases. Therefore, the size and number of air vent holes 5a formed in the balloon 5 are adjusted so that appropriate tension is applied to the partition wall 4. Further, the air vent hole 5 a is also useful for ensuring the adhesion between the balloon 5 and the partition wall 4. Since the partition wall 4 does not have elasticity, there are many wrinkles or the like in the contracted state, and the outer peripheral surface is flattened as it is expanded. At this time, if the air vent hole 5a is formed in the balloon 5, the air that has entered between the wrinkles of the partition wall 4 can be quickly released from the air vent hole 5a. Is stretched in close contact with the partition wall 4.

  The fuel tank 1 is sandwiched between a quick connector 6 and a holder 9 for taking out methanol in the inner container 3 to the fuel cell system side and supplying methanol to the inner container 3, and this quick connector 6 is connected to the fuel cell. It is connected to the system-side connector and constitutes a fuel flow path. Accordingly, the liquid fuel in the interior container 3 is sucked up by the liquid fuel supply pump on the fuel cell system side through the quick connector 6 and supplied to the fuel cell.

  The interior container 3 is attached to the holder 9. An inner container 3 (partition wall 4 and balloon 5) is attached to the outer peripheral surface of the inner container 3 with an O-ring 7 while maintaining airtightness. In the sealed portion by the O-ring 7, the inner diameter of the outer container 2 is made small, and the O-ring 7 is pressed by the inner peripheral surface of the outer peripheral container 2 to improve the sealing performance.

  The holder 9 includes a liquid fuel circulation pipe 8 inserted into the interior container 3, and the liquid fuel is filled or discharged into the interior container 3 through the liquid fuel circulation pipe 8. Here, the partition wall 4 is formed of a non-stretchable film. If the liquid fuel therein is taken out to the end, wrinkles and sagging occur in the partition wall 4 and the contraction force of the balloon 5 is not transmitted. A large suction force is required to suck out by the fuel supply pump on the system side.

  Therefore, in the fuel tank 1 of the present embodiment, the liquid fuel circulation pipe 8 is formed of fluororesin (PFA) and a large number of liquid fuel circulation holes 8a are provided. By disposing such an outer perforated tube as the liquid fuel circulation hole 8a, it is possible to suck out with a small suction force even if the remaining amount of liquid fuel is small.

  In the fuel tank 1 configured as described above, the inner container 3 has a double structure, and the partition wall 4 containing the liquid fuel is formed of a fluorine-based resin, so that transpiration due to permeation of liquid fuel such as methanol is reduced. be able to. Therefore, not only can an economic effect be obtained, it is also advantageous in terms of safety. Further, in the fuel tank 1 of the present embodiment, since the stretchability is imparted to the interior container 3 in which the liquid fuel is accommodated by the balloon 5 that is a stretchable member, the fuel is smoothly supplied to the end by the contraction force. Is possible.

  The fuel tank having the above-described configuration can be incorporated in a fuel cell system as shown in FIG. Hereinafter, this fuel cell system will be described.

  The fuel cell system of this example includes a fuel cell stack 11 that generates power, an air supply system that supplies air to the fuel cell stack 11, a fuel supply system that supplies fuel, a water treatment mechanism, a control controller 12 that controls these, It is composed of a DC-DC converter 13 driven by power generated by the fuel cell stack 11, a load 14, and the like.

  The air supply system includes an air supply pump 15, and the fuel supply system includes a methanol tank 16, a methanol supply pump 17, a fuel mixer 18, and a fuel aqueous solution circulation pump 19. As the methanol tank 16, the fuel tank having the structure described above is used. The water treatment mechanism includes a gas-liquid separator 20, a moisture reservoir 21, and a treatment device 22, and an electromagnetic valve 23, a carbon dioxide remover 24, and the like are attached thereto.

  In the fuel cell system having the above-described configuration, the methanol supply pump 17 sucks methanol from the methanol tank 16 and supplies it to the fuel mixer 18. At this time, methanol is smoothly supplied from the methanol tank 16 by pushing out by the contraction force in the interior container of the methanol tank 16 and sucking up by the methanol supply pump 17.

  The aqueous fuel solution circulation pump 19 supplies the aqueous fuel solution to the fuel cell stack 11 from the fuel mixer 18 that mixes methanol and moisture to generate the aqueous fuel solution. The aqueous fuel solution consumed in the fuel cell stack 11 is circulated to the fuel mixer 18 provided with the carbon dioxide remover 24 and is supplied to the fuel cell stack 11 again by the aqueous fuel solution circulation pump 19. The fuel mixer 18 equipped with the carbon dioxide remover 24 separates carbon dioxide from the discharged liquid discharged by the fuel cell stack 11 and sends it to the processing device 22, which discharges the carbon dioxide into the atmosphere. In a fuel cell system using a liquid fuel such as methanol, the liquid fuel itself is a cooling medium for the fuel cell, and the fuel cell system does not require a separate cooling channel. In addition, the fuel cell system using liquid fuel has an advantage that a back pressure valve is not required as compared with the case of using gaseous fuel such as hydrogen gas because the liquid fuel itself is incompressible.

  The air supply pump 15 takes in air as an oxidant from the atmosphere and supplies it to the fuel cell stack 11. The air used for power generation in the fuel cell stack 11 is separated from moisture by the gas-liquid separator 20 and discharged into the atmosphere via the processing device 22. The separated water is stored in the water reservoir 21 and then sent to the fuel mixer 18 where it is used to generate an aqueous fuel solution. The electromagnetic valve 23 provided between the moisture reservoir 21 and the fuel mixer 18 adjusts the amount of water supplied from the moisture reservoir 21 to the fuel mixer 18.

  Further, the DC-DC converter 13 connected to the fuel cell stack 11 and the load 14 connected to the DC-DC converter 13 are driven by taking out power from the fuel cell stack 11. The controller 12 controls driving of each device constituting the fuel cell system.

  As mentioned above, although specific embodiment of this invention was described, it cannot be overemphasized that this invention is not restricted to these embodiment, A various change is possible in the range which does not deviate from the summary of this invention. For example, each embodiment has been described with reference to the case where methanol is used as the fuel. However, the embodiments can be applied to all fuel tanks of fuel cell systems using liquid fuel such as hydrocarbon fuel.

It is a schematic sectional drawing which shows an example of the fuel tank to which this invention is applied. It is a principal part expanded sectional view which expands and shows an interior container. It is a block diagram which shows the structural example of a fuel cell system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel tank 2 Exterior container 3 Interior container 4 Partition 5 Balloon 5a Air vent hole 6 Quick connector 8 Liquid fuel circulation pipe 8a Liquid fuel circulation hole 9 Holder 11 Fuel cell stack 16 Methanol tank 17 Methanol supply pump

Claims (11)

In a fuel tank provided with an interior container that contains liquid fuel in the exterior container,
The interior container is composed of a partition made of a fluorine-based resin and a stretchable member that wraps the outside thereof, and has a double structure,
The outer container is attached to the holder in a form sandwiched between quick connectors,
The interior container opening is attached in Rutotomoni to the holder, the holder is in the interior container, the liquid fuel flow holes in which liquid fuel is circulated is provided with a liquid fuel flow pipe which is plurally formed on the outer periphery
Fuel tank for direct methanol fuel cell . Before SL elastic member is a balloon made of latex rubber, a direct methanol fuel cell fuel tank according to claim 1. The front Symbol elastic member, an air vent hole is formed, a direct methanol fuel cell fuel tank according to claim 1. Before SL septum, said has a size corresponding to the size of the outer container, the elastic member, the possible extension corresponding to the magnitude of the external container, direct methanol according to claim 1 Fuel tank for fuel cells . Before SL liquid fuel circulation pipe is formed by a fluororesin, a direct methanol fuel cell fuel tank according to claim 1. In a fuel cell system including a fuel cell and a fuel tank that supplies liquid fuel that is fuel to the fuel cell,
The fuel tank is a fuel tank provided with an interior container that contains liquid fuel in an exterior container,
The interior container is composed of a partition made of a fluorine-based resin and a stretchable member that wraps the outside thereof, and has a double structure,
The outer container is attached to the holder in a form sandwiched between quick connectors,
The interior container opening is attached in Rutotomoni to the holder, the holder is in the interior container, the liquid fuel flow holes in which liquid fuel is circulated is provided with a liquid fuel flow pipe which is plurally formed on the outer periphery
Direct methanol fuel cell system. Before SL elastic member is a balloon made of latex rubber, a direct methanol fuel cell system according to claim 6. The front Symbol elastic member, an air vent hole is formed, a direct methanol fuel cell system according to claim 6. Before SL septum, said has a size corresponding to the size of the outer container, the elastic member, the possible extension corresponding to the magnitude of the external container, direct methanol according to claim 6 Fuel cell system. A liquid fuel supply pump for supplying the liquid fuel in the fuel tank to the fuel cell, and the liquid fuel is discharged from the fuel tank by suction by the liquid fuel supply pump and extrusion by a contraction force of the expansion and contraction member of the fuel tank; The direct methanol fuel cell system according to claim 6 . The direct methanol fuel cell system according to claim 6 , wherein liquid fuel is discharged from the fuel tank by pushing out by a contraction force of the expansion and contraction member of the fuel tank.

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