JP2008218058A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell which has a structure that can improve easiness of an assembly work without impairing small size and which is superior in reliability while enabling a stabilized output. <P>SOLUTION: The fuel cell is provided with a fuel battery cell 2 including a membrane electrode assembly having a fuel electrode, an air electrode, and an electrolyte membrane interposed between the fuel electrode and the air electrode, and a fuel supply mechanism 30 to supply fuel to the fuel battery cell 2. The fuel supply mechanism 30 has a housing part 31A for housing the fuel battery cell 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell using liquid fuel.

  In recent years, attempts have been made to use a fuel cell as a power source for portable electronic devices such as notebook computers and mobile phones so that they can be used for a long time without being charged. A fuel cell is characterized in that it can generate electric power simply by supplying fuel and air, and can generate electric power continuously for a long time if fuel is replenished. For this reason, if the fuel cell can be reduced in size, it can be said that the system is extremely advantageous as a power source for portable electronic devices.

  A direct methanol fuel cell (DMFC) is promising as a power source for portable electronic devices because it can be miniaturized and the fuel can be easily handled. As the liquid fuel supply method in the DMFC, there are known an active method such as a gas supply type and a liquid supply type, and a passive method such as an internal vaporization type in which the liquid fuel in the fuel container is vaporized inside the cell and supplied to the fuel electrode. It has been.

  Among these, a passive system such as an internal vaporization type is particularly advantageous for downsizing of the DMFC. In the passive DMFC, for example, a structure is proposed in which a membrane electrode assembly (fuel cell) having a fuel electrode, an electrolyte membrane, and an air electrode is disposed on a fuel containing portion made of a resin box-like container ( For example, see Patent Documents 1 and 2). When the fuel vaporized from the fuel container is directly supplied to the fuel cell, it is important to improve the output controllability of the fuel cell, but the current passive DMFC does not always have sufficient output controllability. .

On the other hand, in a passive DMFC, as a structure for joining a fuel cell (electrode membrane structure) and a fuel storage portion (fuel storage portion), the electrode membrane structure is stacked on the flange portion of the fuel storage portion, and the cover plate The fuel container is attached to the electrode membrane structure by bending the periphery of the electrode membrane structure along the outer periphery of the electrode membrane structure, the outer periphery of the flange portion, and the periphery of the back surface, and sandwiching the electrode membrane structure and the flange portion with the periphery of the cover plate. The structure which fixes to is proposed (for example, refer to patent documents 3).
International Publication No. 2005/112172 Pamphlet JP 2006-318712 A International Publication No. 2005/120966 Pamphlet

  An object of the present invention is to provide a fuel cell having a structure capable of improving the ease of assembly work without impairing downsizing, and having excellent reliability and stabilizing the output. It is to provide.

The fuel cell according to the first aspect of the present invention comprises:
An electromotive part comprising a membrane electrode assembly having a fuel electrode, an air electrode, and an electrolyte membrane sandwiched between the fuel electrode and the air electrode;
A fuel supply mechanism that is disposed on the fuel electrode side of the membrane electrode assembly and supplies fuel to the fuel electrode;
The fuel supply mechanism includes an accommodating portion for accommodating the membrane electrode assembly.

A fuel cell according to a second aspect of the present invention comprises:
A membrane electrode assembly having a fuel electrode, an air electrode, and an electrolyte membrane sandwiched between the fuel electrode and the air electrode;
A liquid fuel containing portion containing liquid fuel and having an opening for deriving a vaporized component of the liquid fuel;
A gas-liquid separation membrane that is disposed so as to close the opening of the liquid fuel storage portion and allows a vaporized component of the liquid fuel to permeate toward the membrane electrode assembly,
The liquid fuel storage unit includes a storage unit for storing the gas-liquid separation membrane and the membrane electrode assembly.

  According to the present invention, there is provided a fuel cell having a structure capable of improving the ease of assembly work without impairing downsizing, and having excellent reliability and stabilizing output. Can be provided.

  A fuel cell according to an embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a plan view showing the appearance of a fuel cell 1 according to this embodiment, and FIG. 2 shows the fuel cell 1 shown in FIG. 1 in a first direction (here, the longitudinal direction of the fuel cell 1) H. FIG. 3 is a view showing a cross section cut along the second direction (here, a direction orthogonal to the longitudinal direction of the fuel cell 1) V of the fuel cell 1 shown in FIG. FIG.

  In this embodiment, the fuel cell 1 includes a fuel cell 2 that constitutes an electromotive unit of the fuel cell 1, and a fuel supply mechanism 30 that supplies fuel to the fuel cell 2. Yes.

  As shown in FIGS. 2 and 3, in the fuel cell 1, the fuel cell 2 includes an anode (fuel electrode) 13 having an anode catalyst layer 11 and an anode gas diffusion layer 12, a cathode catalyst layer 14, and a cathode gas diffusion. Membrane electrode junction comprising a cathode (air electrode / oxidizer electrode) 16 having a layer 15 and a proton (hydrogen ion) conductive electrolyte membrane 17 sandwiched between the anode catalyst layer 11 and the cathode catalyst layer 14 It has a body (Membrane Electrode Assembly: MEA).

  Examples of the catalyst contained in the anode catalyst layer 11 and the cathode catalyst layer 14 include platinum such as platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), and palladium (Pd). Examples thereof include a group element simple substance and an alloy containing a platinum group element. For the anode catalyst layer 11, it is preferable to use Pt—Ru, Pt—Mo, or the like having strong resistance to methanol, carbon monoxide, or the like. Pt, Pt—Ni or the like is preferably used for the cathode catalyst layer 14. However, the catalyst is not limited to these, and various substances having catalytic activity can be used. The catalyst may be either a supported catalyst using a conductive support such as a carbon material or an unsupported catalyst.

  Examples of the proton conductive material constituting the electrolyte membrane 17 include a fluorine-based resin (Nafion (trade name, manufactured by DuPont) or Flemion (trade name, manufactured by Asahi Glass Co., Ltd.) such as a perfluorosulfonic acid polymer having a sulfonic acid group. Etc.), organic materials such as hydrocarbon resins having a sulfonic acid group, or inorganic materials such as tungstic acid and phosphotungstic acid. However, the proton conductive electrolyte membrane 17 is not limited to these.

  The anode gas diffusion layer 12 laminated on the anode catalyst layer 11 serves to uniformly supply fuel to the anode catalyst layer 11 and also serves as a current collector for the anode catalyst layer 11. The cathode gas diffusion layer 15 laminated on the cathode catalyst layer 14 serves to uniformly supply the oxidant to the cathode catalyst layer 14 and also serves as a current collector for the cathode catalyst layer 14. The anode gas diffusion layer 12 and the cathode gas diffusion layer 15 are made of a porous substrate.

  A conductive layer is laminated on the anode gas diffusion layer 12 and the cathode gas diffusion layer 15 as necessary. These conductive layers include, for example, a mesh made of a conductive metal material such as gold (Au), a porous film, a thin film or a foil, or a conductive metal material such as stainless steel (SUS) and a good conductivity such as gold. A metal-coated composite material or the like is used.

  2 and 3, the fuel cell 2 is described as a single unit, but a plurality of anodes and cathodes are formed on the same electrolyte membrane 17 so as to face each other and are directly electrically connected. It may be a structure.

  As shown in FIGS. 1 to 4, the fuel supply mechanism 30 is arranged on the anode (fuel electrode) 13 side of the fuel cell 2 and supplies fuel to the anode 13 of the fuel cell 2.

  The fuel supply mechanism 30 includes a fuel supply unit 31. The fuel supply mechanism 30 includes a fuel storage unit (not shown) that stores the liquid fuel supplied to the fuel supply unit 31. The fuel storage unit stores liquid fuel corresponding to the fuel battery cell 2, and examples of the liquid fuel include methanol fuels such as aqueous methanol solutions of various concentrations and pure methanol. The liquid fuel is not necessarily limited to methanol fuel. The liquid fuel may be, for example, an ethanol fuel such as an ethanol aqueous solution or pure ethanol, a propanol fuel such as a propanol aqueous solution or pure propanol, a glycol fuel such as a glycol aqueous solution or pure glycol, dimethyl ether, formic acid, or other liquid fuel. In any case, liquid fuel corresponding to the fuel battery cell 2 is used.

  The fuel supply unit 31 and the fuel storage unit are connected via a liquid fuel passage such as a pipe (not shown). That is, liquid fuel is introduced into the fuel supply unit 31 from the fuel storage unit via the flow path. The flow path is not limited to piping independent of the fuel supply unit 31 and the fuel storage unit. For example, when the fuel supply unit 31 and the fuel storage unit are stacked and integrated, a liquid fuel flow path connecting them may be used.

  The fuel supply unit 31 has a fuel inlet 32 through which liquid fuel is injected via a flow path at the bottom thereof, a fuel supply port 33 that supplies liquid fuel injected from the fuel inlet 32 and vaporized components thereof, And a thin tube 34 that connects the fuel inlet 32 and the fuel supply port 33. In the example of the fuel supply unit 31 shown here, the fuel injection port 32 and the fuel supply port 33 are each one place.

  Further, the fuel supply unit 31 has an accommodating portion 31 </ b> A for accommodating at least the fuel battery cell 2 at the upper portion thereof. That is, the fuel supply unit 31 has a bottom surface 35 in which the fuel supply port 33 is formed, and a wall portion 36 protruding from the bottom surface 35, and the accommodating portion 31 </ b> A is formed by the bottom surface 35 and the wall portion 36. Is formed.

  In this embodiment, the wall portion 36 is formed in a frame shape so as to surround the fuel battery cell 2. More specifically, the wall portion 36 is disposed on four sides with respect to the fuel cell 2 having a substantially rectangular flat plate shape. That is, the wall portion 36 extends along the second direction V and extends along the first direction H with the first side wall 36A and the second side wall 36B facing each other with the fuel cell 2 interposed therebetween. A third side wall 36C and a fourth side wall 36D that face each other through the battery cell are included.

  That is, the fuel supply unit 31 shown here is configured as a box-shaped container having both a function of supplying fuel to the fuel cell 2 and a function of housing the fuel cell 2.

  In this embodiment, the fuel cell 1 further includes a cover plate 18 disposed on the cathode (air electrode) 16 side of the fuel cell 2. That is, the fuel battery cell 2 is disposed between the bottom surface 35 of the accommodating portion 31 </ b> A and the cover plate 18. The cover plate 18 has an opening 18A for taking in air as an oxidant. In the example shown in FIGS. 2 and 3, the moisture retention layer 20 is disposed between the cover plate 18 and the cathode 16, but may be omitted. The moisturizing layer 20 has a function of impregnating a part of the water generated in the cathode catalyst layer 14 to suppress transpiration of water and promote uniform diffusion of air to the cathode catalyst layer 14. .

  Further, in this embodiment, the fuel cell 1 includes a support plate 41 that is disposed between the fuel cell 2 and the fuel supply mechanism 30 and supports the fuel cell 2 from the anode 13 side. That is, the fuel cell 2 is held between the support plate 41 and the cover plate 18. The support plate 41 is an opening AP for supplying the fuel supplied from the fuel supply mechanism 30 to the anode 13 of the fuel battery cell 2 in a state where the support plate 41 is disposed between the fuel battery cell 2 and the fuel supply mechanism 30. have. That is, the opening AP is a through-hole penetrating from the fuel supply mechanism 30 side to the fuel cell 2 side in the support plate 41.

  In addition, although such a support plate 41 may be omitted, the following effects can be obtained by applying this. That is, by disposing the support plate 41 between the fuel battery cell 2 and the fuel supply mechanism 30, a distance from the fuel supply port 33 to the fuel battery cell 2 can be secured. For this reason, it is possible to secure a sufficient capacity to promote the vaporization of the liquid fuel supplied from the fuel supply port 33, and it is possible to diffuse the fuel in a gaseous state over a wide range. As a result, the fuel distribution in the plane of the anode 13 can be leveled, and the fuel required for the power generation reaction in the fuel battery cell 2 can be supplied as a whole without excess or deficiency. Therefore, it is possible to efficiently generate a power generation reaction in the fuel cell 2 without causing an increase in size or complexity of the fuel cell 1. As a result, the output of the fuel cell 1 can be improved. In other words, the output and its stability can be improved without impairing the advantages of the fuel cell 1 that does not circulate the fuel.

  Further, since the fuel cell 2 is supported by the support plate 41 and the fuel cell 2 is held between the support plate 41 and the cover plate 18, deformation of the fuel cell 2, particularly the membrane electrode assembly, is deformed. It is possible to suppress the decrease in output by increasing the adhesion between the electromotive unit and the current collector.

  Furthermore, in this embodiment, the fuel cell 1 includes at least one porous body 42 disposed between the fuel cell 2 and the fuel supply mechanism 30. As the constituent material of the porous body 42, various resins are used, and a porous resin film or the like is used as the porous body 42. Such a porous body 42 may be arranged by laminating a plurality of porous films. That is, a porous body mainly having high diffusibility in one direction and a porous body having high diffusivity in a direction intersecting (or orthogonal to) the main body may be used in combination.

  In addition, although such a porous body 42 may be omitted, the following effects can be obtained by applying this. That is, by disposing the porous body 42, the amount of fuel supplied to the anode 13 can be further averaged. That is, the liquid fuel supplied from the fuel supply port 33 of the fuel supply unit 31 is once absorbed by the porous body 42 and diffuses in the in-plane direction inside the porous body 42. Thereafter, the fuel is supplied from the porous body 42 to the anode 13 via the support plate 41, so that the fuel supply amount can be further averaged.

  In short, in the example shown in FIGS. 2 and 3, the fuel cell 1 includes the porous body 42 disposed on the bottom surface 35 and the porous body 42 in the housing portion 31 </ b> A of the fuel supply portion 31 constituting the fuel supply mechanism 30. The fuel cell 2 including the membrane electrode assembly disposed on the support plate 41, the moisture retention layer 20 disposed on the fuel cell 2, and disposed on the moisture retention layer 20. These are held by the cover plate 18. Between the electrolyte membrane 17 and the cover plate 18 (between the electrolyte membrane 17 and the moisturizing layer 20 in the example shown in FIGS. 2 and 3) and between the electrolyte membrane 17 and the support plate 41, respectively. A sealing material 19 such as a rubber O-ring is interposed, and a similar sealing material SE is also interposed between the bottom surface 35 of the fuel supply unit 31 and the support plate 41, and thereby the fuel cell unit. 2 prevents fuel leaks and oxidizer leaks.

  In the fuel cell 1 configured as described above, power is generated by the following process.

  That is, the liquid fuel introduced from the fuel injection port 32 to the fuel supply unit 31 is guided to the fuel supply port 33 via the narrow tube 34. The liquid fuel supplied from the fuel supply port 33 is vaporized and diffused over a wide range. A liquid fuel vaporization component is supplied to the anode 13 of the fuel cell 2.

  In the fuel cell 2, the fuel diffuses through the anode gas diffusion layer 12 and is supplied to the anode catalyst layer 11. When methanol fuel is used as the liquid fuel, the internal reforming reaction of methanol shown in the following formula (1) occurs in the anode catalyst layer 11. When pure methanol is used as the methanol fuel, the water generated in the cathode catalyst layer 14 or the water in the electrolyte membrane 17 is reacted with methanol to cause the internal reforming reaction of the formula (1). Alternatively, the internal reforming reaction is caused by another reaction mechanism that does not require water.

CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ (1)
Electrons (e ⁻ ) generated by this reaction are guided to the outside through a current collector, and are guided to the cathode 16 after operating a portable electronic device or the like as so-called electricity. Further, protons (H ⁺ ) generated by the internal reforming reaction of the formula (1) are guided to the cathode 16 through the electrolyte membrane 17. Air is supplied to the cathode 16 as an oxidant. Electrons (e ⁻ ) and protons (H ⁺ ) that have reached the cathode 16 react with oxygen in the air in the cathode catalyst layer 14 according to the following equation (2), and water is generated with this reaction.

6e ⁻ + 6H ⁺ + (3/2) O ₂ → 3H ₂ O (2)
In the power generation reaction of the fuel cell 1 described above, in order to increase the power to be generated, it is important to make the catalyst reaction smoothly and to make the entire electrode of the fuel cell 2 more effectively contribute to power generation.

  According to the fuel cell 1 configured as described above, the fuel supply cell 30 can be formed without the need for other members by forming the accommodating portion 31A for accommodating the fuel cell 2 in the fuel supply mechanism 30. The fuel battery cell 2 and the fuel supply mechanism 30 can be coupled simply by being accommodated in the accommodating portion 31A. For this reason, it becomes possible to improve the ease of assembly work without impairing downsizing.

  In addition, it is possible to suppress the displacement of the relative position of the fuel cell 2 with respect to the fuel supply mechanism 30, to ensure high sealing performance that can suppress fuel leakage, and to stably supply fuel to the fuel cell 2. It becomes. As a result, the fuel utilization efficiency can be improved, and in addition, the output can be stabilized.

  Further, as in the example shown in FIGS. 2 and 3, in the fuel cell 1 having a plurality of plate-like members such as the support plate 41 and the porous body 42 in addition to the fuel cell 2, the housing portion 31 </ b> A is sequentially provided. By stacking and accommodating the plate-like members, the fuel supply mechanism 30 can be coupled without requiring other members. For this reason, the ease of assembling work is further increased, the mutual displacement between the plurality of plate-like members can be suppressed, and the output stability can be improved.

  Moreover, since the accommodating part 31A has the wall part 36 formed in the frame shape surrounding the fuel battery cell 2, other plate-shaped members including the fuel battery cell 2 are accommodated in the accommodating part 31A. As a result, positioning with respect to the fuel supply mechanism 30 is performed, and the output can be further stabilized.

  Moreover, it is desirable that the total thickness of the plate-like member including the fuel cell 2 disposed between the bottom surface 35 of the accommodating portion 31A and the cover plate 18 is slightly larger than the height of the wall portion 36 of the accommodating portion 31A. That is, the height of the wall portion 36 corresponds to the length from the bottom surface 35 of the wall portion 36 that protrudes from the bottom surface 35 toward the cover plate 18.

  By applying such a configuration, the fuel cell 2 disposed between the bottom surface 35 of the accommodating portion 31A and the cover plate 18 can be held while being pressurized in the thickness direction. For this reason, it is possible to suppress deformation such as bending of the fuel battery cell 2, particularly the membrane electrode assembly, and it is possible to increase the adhesion between the electromotive portion and the current collector to suppress a decrease in output. .

  On the other hand, since the total thickness of the plate-like member is slightly larger than the height of the wall portion 36, each of the plate-like members is elastically deformed when a force for pressing the fuel cell 2 is applied by the cover plate 18. Even so, it is possible to suppress crushing smaller than the height of the wall portion 36, and it is possible to prevent damage caused by excessive force applied to the fuel cell 2.

  The cover plate 18 described above may be fixed to the wall portion 36 of the fuel supply mechanism 30 with screws. In the example shown in FIGS. 1 to 4, the first side wall 36 </ b> A and the second side wall 36 </ b> B of the fuel supply unit 31 have screw holes, and the cover plate 18 also has through holes corresponding to these screw holes. have. The cover plate 18 is fixed to the fuel supply mechanism 30 with screws SC.

  In the example shown in FIG. 4 or the like, the entire wall portion 36 may be provided with screw holes in all four side walls and all four sides may be fastened and fixed with screws. However, in order to secure the screw holes, In order to reduce the size, it is desirable to fasten and fix at least one side or two opposite sides with screws. In addition, the fastening and fixing with the screw may be fixed by fastening the screw into the screw hole, but may be the fastening and fixing using a nut.

  Further, the cover plate 18 described above may be bent along the wall portion 36 and the rear peripheral edge portion 31 </ b> B of the fuel supply mechanism 30 and fixed to the fuel supply mechanism 30. In the example shown in FIGS. 1 to 4, the third side wall 36C and the fourth side wall 36D of the fuel supply unit 31 are formed in a thin plate shape. After the fuel cell 2 or the like is accommodated in the accommodating part 31A with respect to such a fuel supply part 31, the flat cover plate 18 is overlapped, and the peripheral part of the cover plate 18 is bent at a substantially right angle to form the third side wall. 36C and the fourth side wall 36D are brought into close contact with each other, and the peripheral tip portion of the cover plate 18 is further bent at a substantially right angle to be brought into close contact with the rear peripheral portion 31B of the fuel supply unit 31. Thus, the cover plate 18 sandwiches the fuel supply mechanism 30 in a state where the plate-like members are accommodated in the accommodating portion 31A.

  Further, it is desirable that the above-described fuel supply mechanism 30, particularly the fuel supply unit 31, is formed using a resin material. In such a case, as a matter of course, the wall portion 36 constituting the housing portion 31A integrated with the fuel supply portion 31 is also formed using the same resin material. More preferably, when methanol is selected as the liquid fuel, the fuel supply mechanism 30 is formed using a resin material having resistance to methanol.

  When the wall portion 36 is formed in a frame shape, the fuel battery cell 2 is surrounded by a resin material, that is, an insulator. That is, the cover plate 18 is mainly made of metal such as stainless steel. On the other hand, the electrolyte membrane 17 included in the fuel cell 2 is drawn out from the sealing material 19. For this reason, if the end of the electrolyte membrane 17 touches the peripheral edge of the cover plate 18, there is a risk of corrosion. On the other hand, in the configuration in which the fuel cell 2 is accommodated in the resin accommodating portion 31A, since the resin wall portion 36 is interposed between the cover plate 18 and the fuel cell 2, the fuel cell. 2 can eliminate the contact point that contacts the cover plate 18, and corrosion can be suppressed.

  Next, a modification of the above-described embodiment will be described.

  The fuel supply mechanism 30 is not limited to the configuration described above, and various changes can be made. That is, in the modification shown in FIG. 5, the fuel supply unit 31 constituting the fuel supply mechanism 30 includes a fuel injection port 32 into which liquid fuel is injected via a flow path and a fuel injection port 32. A plurality of fuel supply ports 33 for supplying the liquid fuel injected from the fuel and its vaporized components, and a thin tube 34 connecting the fuel injection port 32 and each fuel supply port 33.

  The fuel supply unit 31 also has an accommodating portion 31 </ b> A for accommodating at least the fuel battery cell 2 at the top thereof, as in the above-described embodiment. That is, the fuel supply unit 31 includes a bottom surface 35 in which a plurality of fuel supply ports 33 are formed, and a wall portion 36 protruding from the bottom surface 35, and the storage portion is formed by the bottom surface 35 and the wall portion 36. 31A is formed.

  In the fuel supply mechanism 30 having such a configuration, the liquid fuel injected from the fuel injection port 32 into the fuel supply unit 31 can be guided to the plurality of fuel supply ports 33 via the thin tubes 34 branched into a plurality of branches. Is possible. That is, by applying such a fuel supply mechanism 30, the liquid fuel injected from the fuel injection port 32 can be evenly distributed to the plurality of fuel supply ports 33 regardless of the direction or position. Therefore, the uniformity of the power generation reaction in the plane of the fuel cell 2 can be further enhanced.

  Further, by connecting the fuel injection port 32 and the plurality of fuel supply ports 33 with the thin tubes 34, it is possible to design to supply more fuel to a specific location of the fuel cell 1. For example, in the case where the heat dissipation by half of the fuel cell 1 is improved due to the convenience of mounting the device, a temperature distribution is conventionally generated, and a decrease in average output is inevitable. On the other hand, by adjusting the formation pattern of the thin tubes 34 and arranging the fuel supply ports 33 densely in a portion where heat dissipation is good in advance, it is possible to increase the heat generated by the power generation in that portion. Thereby, the in-plane power generation degree can be made uniform, and it is possible to suppress a decrease in output.

  Also in the fuel cell 1 of such a modification, the effect similar to embodiment mentioned above is acquired.

  In the embodiment described above, the mechanism for feeding the liquid fuel from the fuel storage unit to the fuel supply unit 31 is not particularly limited. For example, when the installation location at the time of use is fixed, the liquid fuel can be dropped from the fuel storage unit to the fuel supply unit 31 and fed using gravity. Further, by using a flow path filled with a porous body or the like, liquid can be fed from the fuel storage portion to the fuel supply portion 31 by a capillary phenomenon.

  Furthermore, liquid feeding from the fuel storage unit to the fuel supply unit 31 may be performed by a pump. In this case, for example, a configuration in which a pump is inserted in the middle of the flow path between the fuel storage unit and the fuel supply unit 31 is applicable. The pump in this case is not a circulation pump that circulates fuel, but a fuel supply pump that sends liquid fuel from the fuel storage unit to the fuel supply unit 31 to the last. By supplying liquid fuel when necessary with such a pump, the controllability of the fuel supply amount can be improved.

  The type of pump is not particularly limited, but a rotary vane pump, an electroosmotic pump, a diaphragm pump, It is preferable to use an ironing pump or the like. A rotary vane pump feeds liquid by rotating a wing with a motor. The electroosmotic flow pump uses a sintered porous material such as silica that causes an electroosmotic flow phenomenon. The diaphragm pump is a pump that feeds liquid by driving the diaphragm with an electromagnet or piezoelectric ceramics. The squeezing pump presses a part of the flexible fuel flow path and squeezes the fuel. Among these, it is more preferable to use an electroosmotic pump or a diaphragm pump having piezoelectric ceramics from the viewpoint of driving power, size, and the like.

  When such a pump is applied, a control circuit for controlling the operation of the pump may be added. That is, it is preferable to control the fuel supply (liquid feeding) pump with reference to the output of the fuel cell 1. For this reason, the output of the fuel cell 1 is detected by the control circuit, and a control signal is sent from the control circuit to the pump based on the detection result. The pump is controlled to be turned on / off based on a control signal sent from the control circuit. More stable operation can be achieved by controlling the operation of the pump based on temperature information, operation state information of an electronic device that is a power supply destination, and the like in addition to the output of the fuel cell 1.

  Furthermore, in order to improve the stability and reliability of the fuel cell 1, a fuel cutoff valve may be arranged in series with the pump. In this case, a configuration in which a fuel cutoff valve is inserted in the flow path between the pump and the fuel supply unit 31 is applicable. However, even if the fuel cutoff valve is installed between the pump and the fuel supply unit 31, There is no hindrance. As the fuel cutoff valve, an electrically driven valve capable of controlling the opening / closing operation with an electric signal using an electromagnet, a motor, a shape memory alloy, piezoelectric ceramics, bimetal or the like as an actuator is used. As the fuel cutoff valve, it is preferable to use an electrically driven valve using an electromagnet or a piezoelectric ceramic from the viewpoint of its size, drive power and the like. Furthermore, it is preferable to use a latch type valve having a state maintaining function as the fuel cutoff valve.

  Further, if the fuel is supplied from the fuel supply mechanism 30 to the fuel battery cell 2, a fuel cutoff valve may be arranged instead of the pump. In this case, the fuel cutoff valve is provided to control the supply of liquid fuel through the flow path.

  In addition, a balance valve that balances the pressure in the fuel storage portion with the outside air may be attached to the fuel storage portion or the flow path.

  Next, another embodiment of the fuel cell 1 including the fuel cell 2 configured as described above will be described.

  As shown in FIG. 6, the fuel cell 1 is mainly composed of a fuel cell 2, a liquid fuel storage unit 70, and a gas-liquid separation membrane 80. The liquid fuel storage unit 70 is configured in a box shape so as to store a liquid fuel such as methanol, and has an opening 71 for deriving a vaporized component of the liquid fuel. The gas-liquid separation membrane 80 is disposed so as to close the opening 71 of the liquid fuel storage unit 70, and is formed of a membrane that transmits the vaporized component of the liquid fuel and does not allow the liquid fuel to pass. Examples of the material of the gas-liquid separation membrane 80 include fluorine-based resins such as silicon and polytetrafluoroethylene.

  In the example shown in FIG. 6, the support plate 41 is disposed between the gas-liquid separation membrane 80 and the fuel cell 2, but may be omitted.

  The liquid fuel storage unit 70 described above has a storage unit 70 </ b> A for storing the gas-liquid separation membrane 80 and the fuel battery cell 2. That is, the liquid fuel storage portion 70 has a storage portion for storing the liquid fuel at the bottom, and has a storage portion 70A for storing the fuel cells 2 and the like at the top. .

  Similar effects can be obtained in the fuel cell 1 of the other embodiment.

  The fuel cell 1 of each embodiment described above is effective when various liquid fuels are used, and the type and concentration of the liquid fuel are not limited. The fuel cell 1 of each embodiment can particularly exhibit its performance and effects when methanol having a concentration of 80 wt% or more is used as the liquid fuel. Therefore, each embodiment is preferably applied to the fuel cell 1 using a methanol aqueous solution or pure methanol having a concentration of 80 wt% or more as a liquid fuel.

  The present invention can be applied to various fuel cells using liquid fuel. In addition, the specific configuration of the fuel cell, the supply state of the fuel, and the like are not particularly limited, and all of the fuel supplied to the MEA is liquid fuel vapor, all is liquid fuel, or part is liquid state. The present invention can be applied to various forms such as a vapor of supplied liquid fuel. In the implementation stage, the constituent elements can be modified and embodied without departing from the technical idea of the present invention. Furthermore, various modifications are possible, such as appropriately combining a plurality of constituent elements shown in the above embodiment, or deleting some constituent elements from all the constituent elements shown in the embodiment. Embodiments of the present invention can be expanded or modified within the scope of the technical idea of the present invention, and these expanded and modified embodiments are also included in the technical scope of the present invention.

FIG. 1 is a plan view schematically showing the appearance of a fuel cell according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing a cross section when the fuel cell shown in FIG. 1 is cut along the first direction. FIG. 3 is a cross-sectional view schematically showing a cross section when the fuel cell shown in FIG. 1 is cut along the second direction. FIG. 4 is a perspective view schematically showing the structure of the fuel supply unit applicable to the fuel cell according to the embodiment of the present invention. FIG. 5 is a cross-sectional view schematically showing the configuration of a fuel cell according to a modification of this embodiment. FIG. 6 is a cross-sectional view schematically showing a configuration of a fuel cell according to another embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell 2 ... Fuel cell 13 ... Anode 16 ... Cathode 17 ... Electrolyte membrane 18 ... Cover plate 30 ... Fuel supply mechanism 31 ... Fuel supply part 31A ... Storage part 31B ... Back surface peripheral part 35 ... Bottom surface 36 ... Wall part 41 ... support plate 42 ... porous body AP ... opening SE ... sealing material SC ... screw 70 ... liquid fuel storage part 70A ... storage part 71 ... opening 80 ... gas-liquid separation membrane

Claims (13)

An electromotive part comprising a membrane electrode assembly having a fuel electrode, an air electrode, and an electrolyte membrane sandwiched between the fuel electrode and the air electrode;
A fuel supply mechanism that is disposed on the fuel electrode side of the membrane electrode assembly and supplies fuel to the fuel electrode;
The fuel supply mechanism according to claim 1, wherein the fuel supply mechanism includes an accommodating portion for accommodating the membrane electrode assembly.   2. The fuel according to claim 1, wherein the housing portion of the fuel supply mechanism is formed by a bottom surface having at least one fuel supply port for supplying fuel and a wall portion protruding from the bottom surface. battery.   The fuel cell according to claim 2, wherein the wall portion is formed in a frame shape so as to surround the membrane electrode assembly. Furthermore, a cover plate disposed on the air electrode side of the membrane electrode assembly is provided,
The fuel cell according to claim 2, wherein the membrane electrode assembly is disposed between a bottom surface of the housing portion and the cover plate.   The total thickness of the plate-like member including the membrane electrode assembly disposed between the bottom surface of the housing portion and the cover plate is larger than the height of the wall portion of the housing portion. The fuel cell as described.   The fuel cell according to claim 4, wherein the cover plate is fastened and fixed to a wall portion of the fuel supply mechanism with a screw.   The fuel cell according to claim 4, wherein the cover plate is bent along a wall portion and a rear peripheral edge portion of the fuel supply mechanism, and is fixed to the fuel supply mechanism.   The fuel cell according to claim 1, wherein the fuel supply mechanism is formed using a resin material.   The fuel cell according to claim 1, further comprising at least one porous body disposed between the fuel supply mechanism and the membrane electrode assembly.   The fuel cell according to claim 1, further comprising a support plate that supports the membrane electrode assembly from the fuel electrode side.   The fuel cell according to claim 1, wherein the fuel is methanol fuel.   The fuel cell according to claim 11, wherein the methanol fuel is a methanol aqueous solution or pure methanol having a methanol concentration of 80 wt% or more. An electromotive part comprising a membrane electrode assembly having a fuel electrode, an air electrode, and an electrolyte membrane sandwiched between the fuel electrode and the air electrode;
A liquid fuel containing portion containing liquid fuel and having an opening for deriving a vaporized component of the liquid fuel;
A gas-liquid separation membrane that is disposed so as to close the opening of the liquid fuel storage portion and allows a vaporized component of the liquid fuel to permeate toward the membrane electrode assembly,
The fuel cell according to claim 1, wherein the liquid fuel storage unit includes a storage unit for storing the gas-liquid separation membrane and the membrane electrode assembly.

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