JP5127267B2 - Fuel cell and fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell and a fuel cell system having a planar arrangement effective for the operation of a portable device.

  In recent years, various electronic devices such as personal computers and mobile phones have been miniaturized with the development of semiconductor technology, and attempts have been made to use fuel cells as power sources for these small devices. Fuel cells have the advantage that they can generate electricity simply by supplying fuel and oxidant, and can continuously generate electricity if only the fuel is replenished / replaced. For this reason, if the size can be reduced, it can be said that the system is extremely advantageous for the operation of the portable electronic device. Direct methanol fuel cells (DMFCs), in particular, use methanol with high energy density as the fuel, and since current can be extracted directly from methanol on the electrode catalyst, it is possible to reduce the size and handle the fuel with hydrogen. Since it is easy compared to gas fuel, it is promising as a power supply for small devices, so it is expected to be put into practical use as an optimal power source for cordless portable devices such as mobile phones, portable audio devices, portable game machines, and laptop computers. .

  The DMFC fuel supply system includes a gas supply type DMFC in which liquid fuel is vaporized and then sent into the fuel cell with a blower, etc., a liquid supply type DMFC in which the liquid fuel is directly sent into the fuel cell with a pump, etc. An internal vaporization type DMFC that vaporizes in the interior is known. Among these, the internal vaporization type DMFC is described in Patent Document 1 and Patent Document 2, for example. In the internal vaporization type DMFC, the vaporized component of the liquid fuel held in the fuel permeation layer is diffused in the fuel vaporization layer (anode gas diffusion layer), and the diffused vaporized fuel is supplied to the anode catalyst layer, and the cathode catalyst layer Power generation reaction occurs in the electrolyte membrane with the oxidant from the side.

  Since such an internal vaporization type DMFC has a low operating voltage per unit cell of about 0.3 to 0.5 V, a plurality of unit cells are arranged on the same plane for use in a cordless portable device as a high-output small power source. It is necessary to arrange them in series and connect them in series, and it is necessary to take a large number of power generation units with respect to the entire surface area of the fuel cell.

  However, in order to sufficiently satisfy the output required for DMFC, it has a relatively large area with a large number of openings and laminated parts, but it uses a seal structure such as an O-ring. This prevents liquid fuel from leaking out. Further, in the internal vaporization type DMFC, if the internal seal is incomplete, the ratio of the fuel contributing to the reaction is reduced and the fuel utilization efficiency is lowered, and as a result, the fuel cell performance is lowered. For this reason, internal seals are also important in DMFCs.

In order to fully exhibit the function of the seal structure, it is necessary to apply a considerable pressing force to the seal portion. For example, in the DMFC described in Patent Document 3, the end of the cover plate serving as the outer case is caulked to the main surface of the fuel tank to apply a considerable pressing force to the seal structure between the two, thereby improving the sealing performance It is improving.
Japanese Patent No. 3413111 International Publication Number WO2006 / 057283 International Publication Number WO2006 / 120966

  However, in order to further reduce the size and weight of the DMFC, parts such as the fuel supply mechanism and the cover plate are thinned by thinning them to the limit, so a considerable pressing force can be obtained only by tightening with the conventional caulking structure. It becomes difficult to apply.

  The present invention has been made in order to solve the above-described problems. Even in the demand for further reduction in size and weight of a fuel cell, the sealing performance can be improved, and a sufficiently high output characteristic for operating a portable device can be obtained. An object is to provide a fuel cell and a fuel cell system that can be obtained.

A fuel cell according to the present invention includes a membrane electrode assembly including an electrolyte membrane, an anode electrode laminated on one surface of the electrolyte membrane, and a cathode electrode laminated on the other surface of the electrolyte membrane. A fuel supply section that supplies fuel to the membrane electrode assembly disposed on the anode electrode side of the membrane electrode assembly; and a cover plate that covers the membrane electrode assembly from the cathode electrode side. A fuel cell comprising:
It has a caulking structure that bends an end portion of the cover plate and caulks the fuel supply portion, and a fastening structure that fastens and fixes the cover plate and the fuel supply portion.

A fuel cell system according to the present invention includes a membrane electrode assembly including an electrolyte membrane, an anode electrode laminated on one surface of the electrolyte membrane, and a cathode electrode laminated on the other surface of the electrolyte membrane. An electromotive unit, a fuel supply unit that supplies fuel to the membrane electrode assembly disposed on the anode electrode side of the membrane electrode assembly, and a fuel introduction port for introducing fuel into the fuel supply unit; A cover plate that covers the membrane electrode assembly from the cathode electrode side, an electron output terminal for taking out electrons generated in the membrane electrode assembly to an external load, and a state for detecting the state of the membrane electrode assembly Detecting means; an external control circuit for controlling supply of fuel to the electromotive unit based on status information from the status detecting means; and status information detected by the status detecting means is sent to the external control circuit. A fuel cell system comprising a status output terminal of the eye, and
A caulking structure that bends an end of the cover plate and caulks the fuel supply part; and a fastening structure that fastens and fixes the cover plate and the fuel supply part.
The fuel supply unit has a side wall formed with a plurality of screw holes for passing screws of the fastening structure.
The fuel inlet is disposed between the adjacent screw holes,
The electronic output terminal is led out between the adjacent screw holes,
The state output terminal is led out from between the fuel supply mechanism between the adjacent screw holes and the cover plate.

  According to the present invention, the sealing performance of the fuel cell can be improved, the fuel cell can be reduced in size and weight, and the volume energy density of the fuel cell can be improved. A sufficiently high output characteristic can be obtained for operating a cordless portable device such as a game machine or a notebook computer.

  The fuel cell of the present invention has a caulking structure in which an end portion of a cover plate is bent and crimped to a fuel supply portion, and a fastening structure for fastening and fixing the cover plate and the fuel supply portion.

  In the fuel cell of the present invention, for example, fastening by screws can be adopted as the fastening structure.

  And as a fuel supply part of the fuel cell of the present invention, a fuel distribution mechanism having a plurality of fuel supply ports for supplying fuel to the membrane electrode assembly through which fuel is introduced through a fuel storage part and a flow path Alternatively, it is possible to adopt various structures such as a structure in which fuel is introduced through a fuel storage section and a flow path, and a fuel diffusion material for supplying fuel to the membrane electrode assembly is disposed, and further, a fuel storage chamber and the like. .

  In fastening fastening with screws as a fastening structure for fastening and fixing the cover plate and the fuel supply part, the fuel supply part has a side wall formed with a plurality of screw holes for passing screws for fastening fastening with screws, In order to introduce fuel into the supply unit from the fuel storage unit via the flow path, the fuel supply unit may further include a fuel introduction port that penetrates the side wall of the fuel storage unit between adjacent screw holes.

  By passing screws of the screw fastening structure through both sides of the fuel introduction port, the fastening force point further enters the inside of the fuel cell structure, and the pressing force is further increased as compared with the fastening of the caulking structure alone.

  Further, in the fastening and fixing using screws as the fastening structure for fastening and fixing the cover plate and the fuel supply unit, the fuel supply unit has a side wall formed with a plurality of screw holes for passing screws for fastening and fixing using screws. In order to take out the electrons generated in the membrane electrode assembly to an external load, the electron output terminal can be led out between the fuel supply mechanism between the adjacent screw holes and the cover plate.

  With such a structure, it is possible to effectively seal the opening for taking out the electronic output terminal, and the sealing performance of the lead-out portion to the outside of the electronic output terminal can be effectively improved.

  Further, the fuel cell of the present invention has a plurality of screw holes through which the fuel supply unit passes screws for fastening and fixing by screws as a fastening structure for fastening and fixing the cover plate and the fuel supply unit. In order to take out electrons generated in the membrane electrode assembly to an external load, the state detection is performed between the fuel supply mechanism between the adjacent screw holes and the cover plate. A status output terminal for sending status information detected from the means to the external control circuit can be derived.

  Also in this case, it becomes possible to effectively seal the opening for taking out the state output terminal by adopting such a structure as described above, and the sealing performance of the lead-out portion to the outside of the state output terminal is effective. Can be improved.

  The state information detected by the state detection means includes, for example, temperature information from a temperature sensor that detects the temperature of the membrane electrode assembly, and output voltage information from the voltage detection means that detects the output voltage of the membrane electrode assembly. The status information is at least one of them.

  Furthermore, the fuel cell system of the present invention may include an external control circuit that is connected to the state output terminal of the fuel cell and controls the fuel cell based on the state information of the fuel cell.

  With such a structure, the fuel cell of the present invention can be appropriately controlled.

  Hereinafter, various embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

  First, an overview of the entire fuel cell will be described with reference to FIGS. FIG. 1 is a cross-sectional view schematically showing the fuel cell of the present embodiment in which the cover plate 21 and the fuel supply unit 70 are fastened and fixed by a fastening structure using screws.

  1 A of fuel cells of this embodiment are covered with the cover plate 21 used as an exterior case, the fuel supply part 70 grade | etc., And the cell structure 20 which contains several unit cells inside. The electromotive unit 20 is disposed in the fuel supply unit 70, covered with the cover plate 21, and tightened using a caulking structure and a screw fastening structure, which will be described later. In the electromotive unit 20, the plurality of unit cells constituting the membrane electrode assembly 10 are arranged side by side on substantially the same plane, and both conductive layers (current collectors) 7a and 7b and lead wiring (not shown) Are connected in series.

  The fuel cell 1 </ b> A is configured as one unit in which a plurality of unit cells are integrated by, for example, caulking the end portion 23 of the cover plate 21 to the main surface of the fuel supply unit 70. Further, the cell structure 20 is sandwiched between the cover plate 21 and the fuel supply unit 70 and fastened with screws 86 and nuts 88 to integrally fasten them.

  The unit cell inside the fuel cell 1A is liquid-tightly sealed by the seal members 8a and 8b. O-rings made of highly insulating rubber can be used for the seal members 8a and 8b. These seal members 8a and 8b form various spaces and gaps inside the fuel cell 1A. Among these spaces and gaps, for example, the space on the anode side is used as a gap (reservoir) 40, and the space on the cathode side is used as an air supply unit in which a moisture retention plate (not shown) is accommodated.

  A plurality of fuel supply holes 17b are opened in the anode conductive layer 7b so that fuel of fuel is supplied from the fuel distribution mechanism 11 to the anode gas diffusion layer 5 and the anode catalyst layer 3 through the fuel supply holes 17b. It has become. In the fuel distribution mechanism 11, a large number of fuel supply ports 14 are opened, and fuel is supplied from the liquid reservoir 40 to the anode side of the electromotive unit 20 through the fuel supply ports 14.

  The liquid reservoir 40 is made up of a space of a predetermined capacity whose periphery is defined by the fuel supply unit and the fuel distribution mechanism 11, and the fuel inlet 12 is open at the side of the space as shown in FIGS. 1 to 3. . The fuel introduction port 12 communicates with a fuel storage unit 50 serving as a fuel supply source via a pipe channel 51, passes through the side wall of the fuel supply unit 70, and opens to the liquid reservoir 40. The fuel supply unit 70, the fuel distribution mechanism 11, the fuel storage unit 50, and the flow path 51 are made of a resin material such as polyetheretherketone (PEEK (Trademark)) that hardly causes deterioration such as swelling due to contact with the methanol liquid. It is made with.

  A liquid fuel such as liquid methanol is accommodated in the gap (liquid reservoir) 40. Here, the vaporized component of the liquid fuel means vaporized methanol when liquid methanol is used as the liquid fuel, and from the vaporized component of methanol and the vaporized component of water when an aqueous methanol solution is used as the liquid fuel. Is a mixed gas.

  A liquid fuel impregnated layer (not shown) is provided inside the gap (reservoir) 40. The liquid fuel-impregnated layer supplies fuel uniformly to the gas-liquid separation membrane even when the liquid fuel in the gap (reservoir) 40 is reduced or even when the fuel cell body is placed inclined and the fuel supply is biased. As a result, it is possible to supply the vaporized liquid fuel to the anode catalyst layer 3 uniformly. As the liquid fuel-impregnated layer, for example, multi-rigid fibers such as porous polyester fiber and porous olefin resin, and open-cell porous resin are preferable. In addition to the polyester fiber, it may be composed of various water-absorbing polymers such as acrylic resin, and is composed of a material that can hold the liquid by utilizing the permeability of the liquid, such as a sponge or an aggregate of fibers. . Such a liquid fuel-impregnated portion is effective for supplying an appropriate amount of fuel regardless of the posture of the main body.

  A plurality of gas flow holes 17a are opened in the cathode conductive layer 7a, and the air introduced from the air holes 22 of the cover plate 21 passes through the moisture retaining plate (not shown), and then passes through the gas flow holes 17a. It is supplied to the diffusion layer 4 and the cathode catalyst layer 2. The gas flow hole 17 a of the cathode conductive layer is preferably arranged so that the central axis substantially coincides with the central axis of the vent hole 22 of the cover plate 21.

  The cover plate 21 also serves to pressurize each constituent member including the cell structure 20 and enhance its adhesion, and is formed of a metal plate such as SUS304, for example. The moisturizing plate (not shown) serves to prevent transpiration of the water generated in the cathode catalyst layer 2 and introduces the oxidant into the cathode diffusion layer 4 uniformly by introducing the oxidant into the cathode catalyst layer 2. It also serves as an auxiliary diffusion layer that promotes uniform diffusion. For this moisturizing plate, a porous film having a porosity of, for example, 20 to 60% is preferably used.

  A unit cell of a fuel cell includes a solid electrolyte membrane 6 having proton conductivity, an anode catalyst layer 3, an anode gas diffusion layer 5, a cathode catalyst layer 2 and a cathode gas diffusion layer 4, and constitutes a membrane electrode assembly. Yes. An anode gas diffusion layer 5 is attached to the anode catalyst layer 3. The anode catalyst layer 3 oxidizes the fuel supplied through the gas diffusion layer 5 and extracts electrons and protons from the fuel. The anode catalyst layer 3 is made of, for example, carbon powder containing a catalyst. Examples of the catalyst include fine particles of platinum (Pt), transition metals such as iron (Fe), nickel (Ni), cobalt (Co), ruthenium (Ru) and molybdenum (Mo), oxides thereof, and alloys thereof. Are used. Since it is possible to prevent inactivation of the catalyst due to adsorption of carbon monoxide (CO), it is preferable to use Pt-Ru which is highly resistant to methanol and carbon monoxide as the anode catalyst and platinum as the cathode catalyst. desirable. However, the catalyst is not limited to this. Further, a supported catalyst using a conductive support such as a carbon material may be used, or an unsupported catalyst may be used.

  The anode catalyst layer 3 more preferably contains fine particles of resin used for the electrolyte membrane 6. This is to facilitate the movement of the generated protons. The anode gas diffusion layer 5 is made of, for example, a thin film made of a porous carbon material, and specifically made of carbon paper or carbon fiber.

  The cathode has a cathode catalyst layer 2 and a cathode gas diffusion layer 4. The cathode catalyst layer 2 reduces oxygen and reacts electrons with protons generated in the anode catalyst layer 3 to generate water. For example, similar to the anode catalyst layer 3 and the gas diffusion layer 4 described above. It is configured. That is, the cathode has a laminated structure in which a cathode catalyst layer 2 made of carbon powder containing a catalyst and a cathode gas diffusion layer 4 (gas permeable layer) made of a porous carbon material are stacked in this order from the electrolyte membrane 6 side. ing. The catalyst used for the cathode catalyst layer 2 is the same as that of the anode catalyst layer 3, and the anode catalyst layer 2 may contain fine particles of resin used for the solid electrolyte membrane 6 as well as the anode catalyst layer 2.

  The electrolyte membrane 6 is for transporting protons generated in the anode catalyst layer 3 to the cathode catalyst layer 2 and is made of a material that does not have electron conductivity and can transport protons. For example, it is composed of a polyperfluorosulfonic acid resin film, specifically, a Nafion film manufactured by DuPont, a Flemion film manufactured by Asahi Glass, or an Aciplex film manufactured by Asahi Kasei Kogyo. In addition to polyperfluorosulfonic acid-based resin films, copolymer films of trifluorostyrene derivatives, polybenzimidazole films impregnated with phosphoric acid, aromatic polyether ketone sulfonic acid films, or aliphatic hydrocarbon-based films You may make it comprise the electrolyte membrane 6 which can transport protons, such as a resin container.

  The cathode gas diffusion layer 4 is laminated on the upper surface side of the cathode catalyst layer 2, and the anode gas diffusion layer 5 is laminated on the lower surface side of the anode catalyst layer 3. The cathode gas diffusion layer 4 plays a role of uniformly supplying the oxidizing agent to the cathode catalyst layer 2. On the other hand, the anode gas diffusion layer 5 plays a role of uniformly supplying fuel to the anode catalyst layer 3. The cathode conductive layer 7a and the anode conductive layer 7b are in contact with the cathode gas diffusion layer 4 and the anode gas diffusion layer 5, respectively. As a material constituting the cathode conductive layer 7a and the anode conductive layer 7b, for example, a porous layer (for example, a mesh) or a foil body made of a metal material such as gold, or a highly conductive material such as gold or the like in a conductive metal material such as SUS. A composite material coated with a conductive metal can be used.

  A fuel distribution mechanism 11 is provided below the electromotive unit 20. A plurality of fuel supply ports 14 are opened in the fuel distribution mechanism 11. Fuel is distributed and supplied to the anode catalyst layer 3 through these fuel supply ports 14.

  In addition, it is also possible to arrange a gas-liquid separation membrane (not shown) between the anode conductive layer 7b and the fuel distribution mechanism 11 in the above configuration. The gas-liquid separation membrane is composed of a polytetrafluoroethylene (PTFE) sheet having a large number of pores, and has a property of blocking liquid fuel (methanol liquid or an aqueous solution thereof) and allowing fuel gas (methanol gas) to permeate. is there.

  Next, the fuel supply unit 70 and the cover plate 21 will be described.

  The fuel supply unit 70 has a rectangular box shape as shown in FIGS. 2 and 3, and a rectangular recess surrounded by four side walls corresponds to a space for forming the liquid reservoir 40. The fuel inlet 12 is opened at substantially the center of the short side wall on one side of the fuel supply unit 70. The fuel inlet 12 penetrates the downward convex part of the side wall in the X-axis direction. Rectangular nuts 88 are fitted into the recesses 74 on both sides of the fuel inlet 12. In these rectangular nuts 88, as shown in FIG. It is screwed through the screw hole 73 of the fuel supply unit. The cover plate 21 is fastened to the fuel supply unit 70 by these screw fastening structures 86 and 88.

  FIG. 5 is a partial cross-sectional view when the fuel cell shown in FIG. 4 is cut along the Y-axis line (V-V line). By passing the screw 86 of the screw fastening structure through both sides of the fuel introduction port 12, the fastening force point enters the inside of the fuel cell structure as shown in FIG. 5, and the pressing force is further increased compared to the fastening of the caulking structure alone. . As a result, leakage of fuel to the outside can be effectively prevented.

  Similarly to the above, a screw hole 73 penetrating in the Z-axis direction is formed in the other short side wall of the fuel supply unit 70 so that the cover plate 21 and the fuel supply unit 70 are fastened by screws 86. .

  Further, a plurality of recesses 77 opening upward are provided on the short side wall on the other side of the fuel supply unit 70. These recesses 77 are for forming insertion holes for taking out the various terminals 91, 92, 93 from the fuel cell casing to the outside as shown in FIG. That is, these terminal extraction holes are respectively formed between the recess 77 of the fuel supply unit and the cover plate 21. An insulating seal member is provided on the peripheral wall of the terminal extraction hole. With such a structure, it is possible to effectively seal the opening for taking out various terminals, and it is possible to effectively prevent liquid fuel from leaking out from the terminal extraction opening. . The screw hole 73 is disposed so as to avoid these recesses 77. That is, each of the screw holes 73 penetrates the convex portion of the short side wall.

  As shown in FIG. 4, a pair of electronic output terminals 91 are located near both ends of the short side of the housing, and three state output terminals (monitoring terminal, test terminal) are located near the center of the short side. ) 92 are respectively taken out from the center of the short side as temperature detection terminals 93 as other status output terminals. The electron output terminal 91 on the positive electrode side is connected to the cathode conductive layer 7a as a current collector, and the electron output terminal 91 on the negative electrode side is connected to the anode conductive layer 7b as a current collector. The electronic output terminal 91 sends an output detection signal to the control circuit 32 provided outside the housing. The voltage detection terminal 92 is further connected to adjacent strip-shaped electrodes constituting the unit cell in order to detect a local voltage between the unit cells. These voltage detection terminals 92 send an inter-cell local voltage signal to the control circuit 32 (see FIG. 10). The control circuit 32 constantly monitors whether there is an abnormal value in these inter-cell local voltage signals during operation of the fuel cell.

  The temperature detection terminal 93 is connected to a temperature sensor 94 provided at an appropriate position of the cell structure 20 or a moisture retention plate (not shown). The temperature detection terminal 93 is configured to send a temperature detection signal to the control circuit 32. The temperature sensor 94 is disposed so as to detect the temperature of the central portion of the electromotive unit 20 on the cathode side. For example, a thermistor can be used as the temperature sensor 94.

  A number of recesses 76 are formed in the lower part of the long side wall of the fuel supply unit 70. In these recesses 76, the convex end portion 23 of the cover plate is bent at a substantially right angle by caulking to form a caulking structure for fastening the cover plate 21 to the fuel supply unit 70. 3 and 4 show only one long side, a similar caulking structure is also formed on the opposite long side.

  Next, various fuel supply type fuel cells to which the present invention can be applied will be described with reference to FIGS.

  First, the fuel cell 1B of the system shown in FIGS. 6 and 7 connects the electromotive unit 20, the fuel supply unit 70a that supplies fuel to the electromotive unit 20, and the fuel supply unit 70a and the fuel storage unit 50. And a flow path 51.

  The fuel supply unit 70 used in the embodiment of FIG. 1 distributes the fuel to the plurality of fuel supply ports 14 from the gaps 40 provided therein. For this reason, strictly speaking, a phenomenon is observed in which the temperature on the side close to the fuel inlet 12 is slightly high, and the temperature decreases toward the back. Further, when the fuel cell 1A is tilted, the temperature distribution changes depending on the tilt direction due to the influence of gravity or the like, and a tendency that the reaction in the lower part becomes higher is observed. In practice, sufficient performance can be obtained. However, in order to further improve the output, as shown in FIGS. 6 and 7, the fuel inlet 12 and the plurality of fuel supply ports 14a are connected to the narrow tube 41. It is preferable to use a fuel supply unit 70a having a fuel distribution mechanism communicated with each other.

  A fuel supply unit 70a having a fuel distribution mechanism is disposed on the anode (fuel electrode) side of the electromotive unit 20. The fuel supply unit 70 a is connected to the fuel storage unit 50 by the flow path 51. Liquid fuel is introduced into the fuel supply unit 70 a from the fuel storage unit 50 through the flow path 51. The flow path 51 is not limited to piping independent of the fuel supply unit 70a and the fuel storage unit 50. For example, when the fuel supply unit 70a and the fuel storage unit 50 are stacked and integrated, a liquid fuel flow path connecting them may be used. The fuel supply unit 70 a only needs to be connected to the fuel storage unit 50 via the flow path 51.

  As shown in FIG. 7, the fuel supply unit 70 a includes at least one fuel introduction port 12 into which liquid fuel flows, and a plurality of fuel supply ports 14 a that supply liquid fuel or a vaporized component thereof to the electromotive unit 20. . A thin tube 41 that functions as a liquid fuel passage is formed inside the fuel supply unit 70a. A fuel inlet 12 is provided at one end (starting end) of the thin tube 41. The narrow tube 41 is branched into a plurality of parts along the way, and a fuel supply port 14a is provided at each end portion of the branched thin tube 41. The thin tube 41 is preferably a through hole having an inner diameter of 0.05 to 5 mm, for example.

  The liquid fuel introduced into the fuel supply mechanism 70a from the fuel introduction port 12 is guided to the plurality of fuel supply ports 14a via the plurality of thin tubes 41, respectively. By using the fuel supply unit 70a having such a structure, the liquid fuel injected from the fuel introduction port 12 into the fuel supply unit 70a is evenly distributed to the plurality of fuel supply ports 14a regardless of the direction and position. be able to. Therefore, the uniformity of the power generation reaction in the plane of the electromotive unit 20 can be further enhanced.

  Furthermore, by connecting the fuel introduction port 12 and the plurality of fuel supply ports 14a with the thin tubes 41, it is possible to design such that more fuel is supplied to a specific location of the fuel cell 1B. For example, in the case where the heat radiation of half of the fuel cell 1B is improved due to the convenience of mounting the device, the temperature distribution is conventionally generated, and the average output is inevitably lowered. On the other hand, by adjusting the formation pattern of the thin tubes 41 and arranging the fuel supply ports 14a densely in a portion where heat dissipation is good in advance, it is possible to increase the heat generated by 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.

  The narrow tube 41 and the plurality of fuel supply ports 14a connected from the fuel supply port 12 of the fuel supply unit 70a may be configured by members different from the caulking portion and the fastening portion with the cover plate 21 of the fuel supply unit 70a. good.

A conductive layer is laminated on the anode gas diffusion layer 5 and the cathode gas diffusion layer 4 as necessary. As these conductive layers, for example, a mesh made of a conductive metal material such as Au, a porous film, a thin film, or the like is used. An O-ring 8a is provided as a seal member between the cover plate 21 and the electrolyte membrane 6. Similarly, an O-ring 8 b is provided between the fuel distribution mechanism 11 and the electrolyte membrane 6. These O-rings 8a and 8b are made of a rubber material having a volume resistivity of 10 ¹¹ to 10 ¹⁵ Ω · cm, and these prevent fuel leakage and oxidant leakage from the power generation unit.

  The cover plate 21 has a plurality of ventilation holes (not shown) for taking in air as an oxidizing agent. A moisture retention plate (not shown) is provided between the cover plate 21 and the cathode. The moisturizing plate (not shown) absorbs a part of the water generated in the cathode catalyst layer 2 to suppress the transpiration of water and promotes uniform diffusion of air to the cathode catalyst layer 2. The fuel storage unit 50 stores liquid fuel corresponding to the electromotive unit 20. 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 cell is accommodated.

  Further, in the fuel cell 1C, it is effective to insert the porous body 26 between the fuel supply unit 70a and the anode (fuel electrode) 13 as shown in FIG. In FIG. 8, a fuel supply unit 70 a having a fuel distribution mechanism in which the fuel introduction port 12 and a plurality of fuel supply ports 14 a are communicated with each other by a thin tube 41 is used. Various resins are used as the constituent material of the porous body 26, and a porous resin film or the like is used as the porous body 26. By disposing such a porous body 26, the amount of fuel supplied to the anode can be further averaged. That is, the liquid fuel supplied from the fuel supply port 14 a of the fuel supply unit 70 a is once absorbed by the porous body 26 and diffuses in the in-plane direction inside the porous body 26. Thereafter, the fuel is supplied from the porous body 26 to the anode, so that the fuel supply amount can be further averaged.

  In the embodiment described above, the mechanism for feeding the liquid fuel from the fuel storage unit 50 to the fuel supply unit 70a 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 supply source 50 to the fuel supply unit 70a by using gravity and fed. In addition, liquid can be fed from the fuel storage unit 50 to the fuel supply unit 70 by a capillary phenomenon by a fuel distribution mechanism in which the fuel introduction port 12 and the plurality of fuel supply ports 14a are communicated with each other by a thin tube 41.

  Next, as another embodiment, a fuel cell in which a pump 31 is inserted between the fuel supply source 50 and the fuel distribution mechanism 11 will be described with reference to FIGS. The fuel cell 1D shown in FIG. 9 is obtained by inserting a pump 31 in the middle of the flow path 51 of the fuel cell 1C shown in FIG. 8 to which the passive method is applied, and the other configuration is the same as that of the fuel cell 1C shown in FIG. It is substantially the same. That is, the pump 31 is not a circulating pump through which fuel is circulated, but a fuel supply pump that sends liquid fuel from the fuel storage unit 50 to the fuel supply unit 70a. By feeding liquid fuel with such a pump 31 when necessary, the controllability of the fuel supply amount can be improved. In the fuel cell 1 </ b> D shown in FIG. 9, the fuel supplied from the fuel chest 70 a to the electromotive unit 20 is used for a power generation reaction and is not circulated thereafter and returned to the fuel supply unit 70 a or the fuel storage unit 50. Since the fuel cell 1D shown in FIG. 9 does not circulate the fuel, it is different from the conventional active method, and does not impair the downsizing of the apparatus. Further, since the pump 31 is used for supplying the liquid fuel, which is different from the pure passive method such as the conventional internal vaporization type, the fuel cell 1D shown in FIG. 9 employs a method called a semi-passive type, for example. Is.

  The type of the pump 31 is not particularly limited, but a rotary pump (rotary vane pump) and an electroosmotic flow pump can be used from the viewpoint that a small amount of liquid fuel can be fed with good controllability and can be reduced in size and weight. It is preferable to use a diaphragm pump, a squeezing pump or the like. A rotary pump rotates a wing with a motor and feeds liquid. 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.

  Since the main object of the fuel cell of the present invention is a small electronic device, the amount of liquid fed by the pump 31 is preferably in the range of 10 μL / min to 1 mL / min. If the amount of liquid delivery exceeds 1 mL / min, the amount of liquid fuel delivered at one time becomes too large, and the stop time of the pump 31 occupying the entire operation period becomes long. For this reason, the fluctuation in the amount of fuel supplied to the cell structure 20 increases, and as a result, the fluctuation in output increases. A reservoir for preventing this may be provided between the pump 31 and the fuel supply mechanism 70a. However, even if such a configuration is applied, fluctuations in the fuel supply amount cannot be sufficiently suppressed. This will increase the size of the device.

  On the other hand, if the amount of liquid fed by the pump 31 is less than 10 μL / min, there may be a shortage of supply capacity when the amount of fuel consumption increases when the apparatus is started up. As a result, the start-up characteristics and the like of the fuel cell 1D are degraded. From such a point, it is preferable to use the pump 31 having a liquid feeding capacity in the range of 10 μL / min to 1 mL / min. It is more preferable that the liquid feeding amount of the pump 31 is in the range of 10 to 200 μL / min. In order to stably realize such a liquid feeding amount, it is preferable to apply an electroosmotic flow pump or a diaphragm pump to the pump 31.

  In the fuel cell 1D shown in FIG. 9, the pump 31 is operated when necessary to supply liquid fuel from the fuel storage unit 50 to the fuel supply unit 70a. The liquid fuel introduced into the fuel supply unit 70a is led to the plurality of fuel supply ports 14a, respectively, as in the above-described embodiment. Also in FIG. 9, a fuel supply unit 70 a having a fuel distribution mechanism in which the fuel introduction port 12 and the plurality of fuel supply ports 14 a are communicated with each other by a thin tube 41 is used. Then, fuel is supplied from the plurality of fuel supply ports 14a to the entire surface of the electromotive unit 20, and a power generation reaction is caused. As described above, even when the liquid fuel is fed from the fuel storage unit 50 to the fuel supply unit 70a by the pump 31, the fuel supply unit 70a functions effectively, so the fuel supply amount to the electromotive unit 20 is made uniform. It becomes possible.

  Control of the fuel supply (liquid feeding) pump 31 is preferably performed with reference to the output of the fuel cell 1E as shown in FIG. 10, for example. In FIG. 10, the output of the fuel cell 1E is detected by the control circuit 32, and a control signal is sent to the pump 31 based on the detection result. On / off of the pump 31 is controlled based on a control signal sent from the control circuit 32. The operation of the pump 31 is controlled based on the temperature information, the operation state information of the electronic device that is the power supply destination, etc. in addition to the output of the fuel cell 1E, whereby a more stable operation can be achieved.

  As a specific operation control method of the pump 31, for example, when the output from the fuel cell 1E becomes higher than a predetermined specified value, the pump 31 is stopped or the liquid feeding amount is reduced, and the output becomes lower than the specified value. In such a case, a method of restarting the operation of the pump 31 or increasing the liquid feeding amount can be mentioned. As another operation control method, when the rate of change in output from the fuel cell 1 is positive, the operation of the pump 31 is stopped or the amount of liquid fed is reduced, and when the rate of change in output becomes negative, the pump 31 A method of restarting the operation or increasing the liquid feeding amount can be mentioned.

  Furthermore, in order to improve the stability and reliability of the fuel cell, it is preferable to arrange a fuel cutoff valve 33 in series with the pump 31 as shown in FIG. The fuel cell 1F of FIG. 11 shows a structure in which a fuel cutoff valve 33 is inserted into a flow path 51 between the pump 31 and the fuel supply unit 70a. Even if the fuel cutoff valve 33 is installed between the pump 31 and the fuel storage portion 50, there is no functional problem.

  However, when the fuel cutoff valve 33 is installed in the flow path 51 between the pump 31 and the fuel storage unit 50, for example, when the fuel in the pump 31 is depleted due to evaporation or the like during long-term storage, the liquid fuel from the fuel storage unit 50 There is a risk that the suction function may be hindered. For this reason, the fuel cutoff valve 33 is preferably installed in the flow path 51 between the pump 31 and the fuel supply unit 70a to prevent the liquid fuel from being depleted from the pump 31 during long-term storage.

  In this manner, by inserting the fuel cutoff valve 33 between the fuel storage unit 50 and the fuel resting unit 70a, a small amount of fuel is inevitably generated even when the fuel cell 1F is not used, and the above-described pump re-use is not performed. It is possible to avoid poor suction during operation. These greatly contribute to the improvement of practical convenience of the fuel cell 1.

  Further, the fuel cutoff valve 33 is also effective for the above-described passive fuel cells 1A, 1B, and 1C. For example, in the fuel cells 1A, 1B, and 1C, the fuel cutoff valve 33 is inserted into the flow path 51 that connects the fuel supply unit 7a and the fuel storage unit 50. By applying such a configuration, it is possible to control the supply of fuel to the electromotive unit 20 and improve the output controllability of the fuel cell. The operation control of the fuel cutoff valve 33 in this case can be performed in the same manner as the operation control of the pump 31 described above.

  In addition, if it is the structure by which the fuel supply from the fuel supply part 70a to the electromotive part 20 is performed, it can also be set as the structure which replaces with the pump 31 and arrange | positions only a fuel cutoff valve. In this case, the fuel cutoff valve is provided to control the supply of liquid fuel through the flow path.

  Further, in the fuel cell 1G, it is preferable to install a balance valve 60 that balances the pressure in the fuel storage unit 50 with the outside air in the fuel storage unit 50 and the flow path 51. FIG. 12 shows a state in which the balance valve 60 is installed in the fuel storage unit 50. The balance valve 60 includes a spring 62 that operates the valve movable piece 61 according to the pressure in the fuel storage unit 50, and a seal portion 63 that seals the valve movable piece 61 and closes it.

  When liquid fuel is supplied from the fuel storage unit 50 to the fuel supply unit 70a and the internal pressure of the fuel storage unit 50 is reduced, the valve movable piece 61 of the balance valve 60 receives external pressure and overcomes the repulsive force of the spring 62 and seals. Part 63 is opened. Based on the open state of the balance valve 60, outside air is introduced so as to reduce the pressure difference between the inside and outside. When the pressure difference between the inside and outside is eliminated, the valve movable piece 61 moves again, and the seal portion 63 is sealed.

  By installing the balance valve 60 that operates in this manner in the fuel storage unit 50 or the like, it is possible to suppress fluctuations in the amount of liquid sent due to a decrease in the internal pressure of the fuel storage unit 50 that occurs with the supply of liquid fuel. . That is, when the inside of the fuel storage unit 50 is in a depressurized state, the suction of the liquid fuel by the pump 31 becomes unstable, and the liquid feeding amount is likely to fluctuate. Such fluctuations in the liquid feeding amount can be eliminated by installing the balance valve 60. Therefore, the operational stability of the fuel cell 1G can be improved. When the balance valve 60 is installed in the flow path 51, it is preferably inserted between the fuel storage unit 50 and the pump 31.

  The liquid fuel 49 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. However, the characteristic of the fuel supply unit 70a having the fuel distribution mechanism in which the fuel introduction port 12 and the plurality of fuel supply ports 14a are communicated with each other by the thin tube 41 is more apparent when the fuel concentration is high. For this reason, the fuel cell of each embodiment can exert its performance and effect particularly when methanol having a concentration of 80% or more is used as the liquid fuel. Therefore, each embodiment has a concentration of 80% or more. It is preferable to apply to a fuel cell using methanol as a liquid fuel.

  Although various embodiments have been described above, the present invention is not limited only to the above-described embodiments, and the constituent elements can be modified and embodied without departing from the spirit of the invention in the implementation stage. .

  In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. For example, in each of the above embodiments, a fuel distribution mechanism having a plurality of fuel supply ports for supplying fuel to the membrane electrode assembly, in which fuel is introduced as a fuel supply unit via a fuel storage unit and a flow path However, the fuel supply unit as shown in Patent Document 2 can also be applied to the fuel storage chamber itself, that is, a purely passive fuel cell.

  Furthermore, constituent elements over different embodiments may be appropriately combined. The liquid fuel vapor supplied to the electromotive unit may be all supplied as a liquid fuel vapor, but the present invention can be applied even when a part of the liquid fuel vapor is supplied in a liquid state.

1 is an internal perspective sectional view showing a fuel cell according to an embodiment of the present invention. The perspective view which shows a fuel tank structure. The disassembled perspective view which shows a cover plate and a fuel tank structure (The flow path plate of a fuel distribution mechanism is abbreviate | omitting illustration). The perspective view which shows the external appearance of a fuel cell in order to demonstrate taking out of various terminals. FIG. 5 is a partial cross-sectional view illustrating a positional relationship between a caulking structure and a screw fastening structure by cutting the fuel cell along the line VV in FIG. 4. The block sectional view showing the fuel cell system of other fuel supply methods. The top view which shows the outline | summary of another fuel distribution mechanism. The block sectional view showing the fuel cell system of other fuel supply methods. The block sectional view showing the fuel cell system of other fuel supply methods. The block sectional view showing the fuel cell system of other fuel supply methods. The block sectional view showing the fuel cell system of other fuel supply methods. The block sectional view showing the fuel cell system of other fuel supply methods.

Explanation of symbols

1, 1A-1G ... fuel cell,
2 ... cathode catalyst layer, 3 ... anode catalyst layer,
4 ... cathode gas diffusion layer, 5 ... anode gas diffusion layer,
6 ... electrolyte membrane (proton conductive membrane),
7a ... cathode conductive layer (positive electrode current collector), 7b ... anode conductive layer (negative electrode current collector),
8a, 8b ... sealing member (O-ring),
10 ... Membrane electrode assembly (MEA),
11 ... Fuel distribution mechanism,
12 ... Fuel introduction port, 14, 14a ... Fuel supply port (opening),
17a ... Gas flow hole, 17b ... Fuel supply port 20 ... Electromotive part,
21 ... Cover plate (exterior case),
22 ... vent hole,
23 ... caulking part (cover plate end part),
26 ... porous body,
31 ... Pump, 32 ... Control circuit,
33, 33A ... Fuel cutoff valve (latch valve),
40 ... void (reservoir), 41 ... capillary, 49 ... liquid fuel,
50: Fuel container,
60 ... balance valve,
70, 70a ... fuel supply section,
73 ... screw holes,
74 ... recess (nut receiver),
76 ... Recess (caulking),
77 ... Terminal extraction hole,
83 ... Screw holes, 86 ... Screws, 88 ... Nuts,
91 ... Electronic output terminal, 92 ... Voltage detection terminal (status output terminal),
93: Temperature detection terminal (state output terminal), 94: Temperature sensor (state detection means, thermistor).

Claims (10)

An electromotive part comprising a membrane electrode assembly comprising an electrolyte membrane, an anode electrode laminated on one surface of the electrolyte membrane, and a cathode electrode laminated on the other surface of the electrolyte membrane;
A fuel supply unit for supplying fuel to the membrane electrode assembly disposed on the anode electrode side of the membrane electrode assembly;
A cover plate covering the membrane electrode assembly from the cathode electrode side;
A fuel cell comprising:
A caulking structure that bends an end portion of the cover plate and caulks the fuel supply portion;
A fastening structure for fastening and fixing the cover plate and the fuel supply unit;
A fuel cell comprising: 2. The fuel cell according to claim 1, wherein the fastening structure is fastening with screws. The fuel supply unit is a fuel distribution mechanism having a plurality of fuel supply ports for supplying fuel to the membrane electrode assembly through which fuel is introduced through a fuel storage unit and a flow path. Item 3. The fuel cell according to any one of Items 1 and 2. 3. The fuel supply part is provided with a fuel diffusion part for supplying fuel to the membrane electrode assembly by introducing fuel through a fuel storage part and a flow path. The fuel cell according to any one of the above. The fuel cell according to claim 1, wherein the fuel supply unit is a fuel storage chamber. The fuel supply unit has a side wall formed with a plurality of screw holes for passing screws of the fastening structure.
4. The fuel cell according to claim 3, further comprising a fuel inlet for introducing fuel into the fuel supply section between the adjacent screw holes. The fuel supply unit has a side wall formed with a plurality of screw holes for passing screws of the fastening structure.
It further has an electronic output terminal that is led out from between the fuel supply mechanism between the adjacent screw holes and the cover plate and takes out electrons generated in the membrane electrode assembly to an external load. The fuel cell according to claim 2. The membrane electrode assembly is provided with a state detection means for detecting the state of the membrane electrode assembly,
The fuel supply unit has a side wall formed with a plurality of screw holes for passing screws of the fastening structure.
It further has a state output terminal that is led out from between the fuel supply part between the adjacent screw holes and the cover plate and sends state information detected by the state detecting means to an external control circuit. The fuel cell according to claim 2, characterized in that: The state information detected by the state detection means includes temperature information from a temperature sensor that detects the temperature of the membrane electrode assembly and output voltage information from a voltage detection means that detects an output voltage of the membrane electrode assembly. 8. The fuel cell according to claim 7, wherein the state information is at least one state information. An electromotive unit comprising an electrolyte membrane, a membrane electrode assembly comprising an anode electrode laminated on one surface of the electrolyte membrane, and a cathode electrode laminated on the other surface of the electrolyte membrane;
A fuel supply unit for supplying fuel to the membrane electrode assembly disposed on the anode electrode side of the membrane electrode assembly;
A fuel inlet for introducing fuel into the fuel supply section;
A cover plate covering the membrane electrode assembly from the cathode electrode side;
An electronic output terminal for taking out electrons generated in the membrane electrode assembly to an external load;
State detection means for detecting the state of the membrane electrode assembly;
An external control circuit for controlling the supply of fuel to the electromotive unit based on state information from the state detection means;
A status output terminal for sending status information detected by the status detection means to the external control circuit;
A fuel cell system comprising:
A caulking structure that bends an end portion of the cover plate and caulks the fuel supply portion;
A fastening structure for fastening and fixing the cover plate and the fuel supply unit;
Further comprising
The fuel supply unit has a side wall formed with a plurality of screw holes for passing screws of the fastening structure.
The fuel inlet is disposed between the adjacent screw holes,
The electronic output terminal is led out between the adjacent screw holes,
The state output terminal is led out from between the fuel supply mechanism between the adjacent screw holes and the cover plate.

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