Patent Application
20100266934
Embodiments described herein relate generally to coupler for fuel cell and fuel cell.
In recent years, attempts have been made to use a fuel cell as a power source for various types of portable electronic equipment such as a notebook computer, a cellular phone and the like to make it possible to use them for a long time without recharging. The fuel cell has characteristics that electricity can be generated by merely supplying a fuel and air and generated continuously for a long time by replenishing the fuel. Therefore, if the fuel cell can be made compact, it is a very advantageous system as a power source for portable electronic equipment.
Especially, a direct methanol fuel cell (DMFC) using a methanol fuel having a high energy density is promising as a power source or the like for portable appliances because it can be made compact and its fuel can also be handled with ease. As a method of supplying the liquid fuel of the DMFC, there are known an active method such as a gas supply type, a liquid supply type or the like and a passive method such as an inside vaporization type or the like which supplies the liquid fuel from a fuel tank to a fuel electrode by vaporizing in the cell. The passive method is advantageous for miniaturization of the DMFC.
A passive type DMFC of an internal vaporization type or the like vaporizes the liquid fuel stored in a fuel storing section via, for example, a fuel-impregnated layer, a fuel vaporization layer or the like to supply to the fuel electrode (see, for example, JP-B2 3413111 (Patent Registration) and JP-A 2004-171844 (KOKAI)). The liquid fuel is supplied to the fuel storing section by means of a fuel cartridge. When a satellite type (external injection type) fuel cartridge is used, a coupler comprising a pair of nozzle and socket having a valve mechanism therein is used to supply the liquid fuel by attaching the socket to the fuel storing section or the like of the DMFC and the nozzle to the fuel cartridge, connecting the nozzle attached to the fuel cartridge to the socket attached to the fuel storing section or the like of the DMFC, and contacting the valves arranged within the above valve mechanisms to bring into an open state (see, for example, JP-A 2004-127824 (KOKAI)).
The passive type DMFC of an internal vaporization type or the like is now under downsizing in order to mount on, for example, portable electronic equipment. As a result, a socket to be mounted on the fuel storing section or the like of the DMFC and a nozzle mounted on the fuel cartridge are under downsizing. With the progresses of miniaturization of the above socket and nozzle, the valve to be disposed within them is also formed to be small and to have a small diameter. As such a valve, one having a rod section with a diameter of, for example, about 1 mm is used, and one having a diameter of about 0.8 mm is also being considered in view of further downsizing and diameter reduction.
But, since a conventional valve is made of a resin material and does not necessarily have high strength, its strength tends to become lower with the above-described downsizing and diameter reduction. The valve with lower strength might be deformed or broken if an excessive load is applied when the socket and the nozzle are connected or separated. Since the valve mainly configures the valve mechanism of the socket and the nozzle, it becomes difficult to operate the valve mechanism properly in case of deformation or breakage, and for example, it becomes difficult to supply the liquid fuel from the fuel cartridge to the DMFC when connected, and the liquid fuel might leak from the DMFC and the fuel cartridge in an unconnected state.
A coupler for a fuel cell according to the embodiment has a socket and a nozzle. The socket is provided to the fuel cell and has a valve and an urging component for urging the valve in the direction of closing it. The nozzle is provided to a fuel cartridge for storing a liquid fuel for the fuel cell and has a valve and an urging component for urging the valve in the direction of closing it. The coupler supplies the liquid fuel stored in the fuel cartridge to the fuel cell by opening both the valves by contacting mutually when the socket and the nozzle are connected. At least one valve selected from the socket side and the nozzle side has a head section and rod sections arranged at opposite ends axially of the head section, and the rod section on the contact side is mainly made of a metal member.
Modes of conducting the present embodiment will be described below with reference to the drawings.
The fuel cell 2 has a fuel battery cell 4 which becomes an electromotive portion, a fuel storing section 5 which stores the liquid fuel to be supplied to the fuel battery cell 4, and a fuel receiving portion 6 which supplies the liquid fuel to the fuel storing section 5. The socket 1s which is one of the members configuring the coupler 1 is disposed in the fuel receiving portion 6. The socket 1s has a valve mechanism therein as described later and is in a closed state except when the liquid fuel is supplied. The fuel cell 2 may have a structure that the liquid fuel is supplied directly from the fuel receiving portion 6 to the fuel battery cell 4 without through the fuel storing section 5.
Meanwhile, the cartridge 3 has a cartridge body 7 which is a container for storing the liquid fuel and is provided at its leading end with the nozzle 1n, which discharges the liquid fuel stored in the cartridge body 7 and is the other of the members configuring the coupler 1. The nozzle 1n also has a valve mechanism therein as described later and is in a closed state except when the liquid fuel is discharged. This cartridge 3 is a so-called satellite type (external injection type) cartridge and connected only when the liquid fuel is injected into the fuel cell 2.
The cartridge body 7 stores a liquid fuel suitable for the fuel cell 2, for example, a methanol fuel such as an aqueous methanol solution having a variable concentration, pure methanol or the like for a direct methanol fuel cell (DMFC). The liquid fuel stored in the cartridge body 7 is not necessarily limited to the methanol fuel but may be another liquid fuel, for example, an ethanol fuel such as an aqueous ethanol solution or pure ethanol, a propanol fuel such as an aqueous propanol solution or pure propanol, a glycol fuel such as an aqueous glycol solution or pure glycol, dimethyl ether or formic acid. At any event, a liquid fuel suitable for the fuel cell 2 is stored.
A specific structure of the coupler 1 is described below with reference to
The nozzle 1n is also called a male coupler or a plug and disposed to cover the opening portion on the tip end of the cartridge body 7. A nozzle head 11 has a cylindrical base section 11a, in which the tip end of the cartridge body 7 is fitted, and a small-diameter shaft section 11b which is formed at the tip end. A shaft hole is formed in the shaft section 11b, and a nozzle opening 11c which is connected to the shaft hole is formed in its tip end.
A recessed portion 11d is formed in the top face which is the tip end surface of the shaft section 11b. The recessed portion 11d is formed by recessing the top face of the shaft section 11b, and the nozzle opening 11c is formed in the bottom of the recessed portion 11d. The recessed portion 11d functions as a storing portion for the liquid fuel remaining (adhering to) on the tip end of the nozzle 1n, so that an operator is prevented from touching the liquid fuel. A peripheral groove 11e which is a recessed portion to be fitted with a nozzle holding mechanism 36 of the socket 1s described later is formed in an external peripheral surface of the shaft section 11b of the nozzle head 11. In addition, a key portion 13, which functions as fuel identification means, is disposed mainly on an external peripheral surface of the shaft section 11b of the nozzle head 11 via a key ring 20 described later. The fuel identification means is configured of the key portion 13 and a key groove 54 which is on the side of the socket 1s as described later.
A cup-like valve holder 15 which holds a valve 14 therein is disposed within the base section 11a. The valve holder 15 defines a valve chamber and is fixed with the outer edge portion of its tip end held between the cartridge body 7 and the base section 11a, and a communication hole 15a which becomes a liquid fuel passage is formed at the rear end portion. The valve 14 has a head section 14a and rod sections 14b and 14c which are formed at opposite ends axially. The rod section 14b on the tip end side is a rod section (rod section of the contact side) which is in contact with the rod section 40b on the side of the socket 1s described later. The head section 14a is disposed within the valve chamber defined by the valve holder 15, and the rod section 14b is housed in the shaft hole of the shaft section 11b. Thus, the valve 14 is held by them to be movable back and forth axially.
An O-ring 17 is disposed between the head section 14a and a valve seat 16 which is attached to the inside of the base section 11a. A force to press the head section 14a to the valve seat 16 by an elastic body 18 such as a compression spring or the like is applied to the valve 14, thereby pressing the O-ring 17 by them.
In an unconnected state, the O-ring 17 is pressed to the valve seat 16 by the head section 14a to bring the fuel passage in the nozzle 1n into a closed state. Meanwhile, when the nozzle 1n is connected to the socket 1s, the valve 14 retracts to separate the head section 14a and the O-ring 17 from the valve seat 16, and the fuel passage in the nozzle 1n is put into an open state. Since the liquid fuel flows from the cartridge body 7 into the valve holder 15 through a communication hole 15a, the liquid fuel passage in the nozzle 1n is brought into an open state, allowing to supply the liquid fuel to the socket 1s.
The key ring 20, which is a ring-shaped member having a cam mechanism, and a container nozzle 21 are disposed on the outer surface of the nozzle head 11. During ordinary use, the key ring 20 is engaged with the nozzle head 11 by press-fitting. If a force of bending, twisting or the like is applied when the cartridge 3 is connected to the fuel cell 2, the key ring 20 is rotationally raised by the cam mechanism to release the connected state to separate the nozzle 1n from the socket 1s. For example, the container nozzle 21 is screwed onto the cartridge body 7, so that the nozzle 1n having the nozzle head 11, the valve 14 and the like is fixed to the tip end of the cartridge body 7.
Meanwhile, the socket 1s is also called a female coupler. The socket 1s which is shown in a magnified state in
An inner cylinder portion 33 which defines the valve chamber is disposed inside the outer cylinder portion 31, and the inner cylinder portion 33 is configured of, for example, an intermediate inner cylinder portion 33a and a rear inner cylinder portion 33b. An O-ring 34 is interposed between the intermediate inner cylinder portion 33a and the rear inner cylinder portion 33b to enhance airtightness of the valve chamber.
The front outer cylinder portion 31a has a function to guide the outer circumferential surface of the nozzle head 11 when the nozzle 1n is connected by inserting. A tip end of the nozzle head 11 is not entirely guided by the front outer cylinder portion 31a, and there is a gap between them. Therefore, a ring-shaped guide member 35 is arranged in the socket 1s to guide the tip end of the nozzle 1n (nozzle head 11).
The guide member 35 is arranged inside the front outer cylinder portion 31a and on the front end side of the rear outer cylinder portion 31b. The guide member 35 has plural cutout portions 35a on its front end, a hook portion 36a which is protruded toward the inner diameter side of the nozzle holding mechanism 36 described later is disposed to pass through the cutout portions 35a, and the guide member 35 is pressed to the rear outer cylinder portion 31b by the nozzle holding mechanism to prevent it from dropping from the socket 1s.
The guide member 35 has an inner shape corresponding to the shape of the tip end of the nozzle head 11. Thus, the tip end of the nozzle 1n connected to the socket 1s is guided to restrict an inclination of the nozzle 1n in the connected state. In other words, when the nozzle 1n is in the state connected to the socket 1s, the guide member 35 is arranged at a portion positioned at the tip end of the nozzle head 11. Thus, an effect of guiding the nozzle 1n at the time of connection and a centering effect based on it can be obtained. Thus, the inclination of the nozzle 1n in the connected state can be restricted
An elastic holder 37 such as a rubber holder is mounted on the intermediate inner cylinder portion 33a. The elastic holder 37 has a cylindrical holder body 37a which is elasticized axially on the basis of its bellows-like shape and material property (rubber elasticity), and a flange portion 37b which is provided on its rear end. The elastic holder 37 has the flange portion 37b fixed between the intermediate inner cylinder portion 33a and a ring-shaped projected portion 31c formed on the rear outer cylinder portion 31b.
The elastic holder 37 is a sealing member which forms a contacting seal face with the nozzle head 11 by fitting its tip end into the recessed portion 11d of the nozzle head 11, and its inside is determined to be a liquid fuel passage. In other words, the elastic holder 37 is a sealing member which seals against the outside when the valve mechanism of the socket 1s is released. The recessed portion 11d formed in the shaft section 11b of the nozzle head 11 also has a function of sealing by forming the contacting seal face when it is fitted onto the tip end portion of the elastic holder 37.
A valve 40 is disposed within the socket 1s. The valve 40 has a head section 40a and rod sections 40b and 40c which are formed at opposite ends axially. Here, the rod section 40b of the tip end side is a rod section (rod section on the contact side) which is in contact with the rod section 14b of the valve 14 on the side of the nozzle 1n. The head section 40a is disposed within the valve chamber which is defined by the intermediate inner cylinder portion 33a and the rear inner cylinder portion 33b, the rod section 40b is housed in the elastic holder 37, and the valve 40 is made movable back and forth axially by them.
An O-ring 52 is disposed between the head section 40a and a valve seat 51 which is formed on the inner surface of the front end side of the intermediate inner cylinder portion 33a. A force for pressing the head section 40a to the tip end side by an elastic body 53 such as a compression spring or the like is always applied to the valve 40 to press the O-ring 52, and the fuel passage in the socket 1s is put in a closed state. Meanwhile, when the nozzle 1n is connected to the socket 1s, the valve 40 retracts to separate the head section 40a and the O-ring 52 from the valve seat 51, and the fuel passage in the socket 1s is brought into an open state.
The rear inner cylinder portion 33b is provided with a communication hole 33c which is connected to the fuel storing section 5 through the fuel receiving portion 6. Therefore, when the nozzle 1n is connected to the socket 1s to bring the valves 14 and 40 into an open state, the fuel passages continuously connected from the nozzle 1n to the socket 1s are formed, and the liquid fuel stored in the cartridge 3 can be supplied into the fuel storing section 5 of the fuel cell 2.
The nozzle holding mechanism 36 for holding the connected state when the nozzle 1n is connected to the socket 1s is disposed on the front outer cylinder portion 31a. The nozzle holding mechanism 36 has the hook portion 36a which is protruded toward the inner diameter side of the front outer cylinder portion 31a and an elastic body 36b which applies a pressing force to the hook portion 36a so as to hold the nozzle 1n.
The hook portion 36a is applied with a pressing force toward the inner diameter side by an elastic force of the elastic body 36b which is disposed on the outer surface of the front outer cylinder portion 31a and also retractable to the outer diameter side. The nozzle holding mechanism 36 holds the connected state of the nozzle 1n and the socket 1s by engaging the hook portion 36a with the peripheral groove 11e of the nozzle head 11 when the nozzle 1n is connected to the socket 1s. In the connected state, the nozzle 1n is elastically held by the hook portion 36a, and if an excessive force of bending, twisting or the like is applied to the nozzle 1n, the hook portion 36a retracts to release the connected state of the nozzle 1n and the socket 1s.
The key groove 54, which is a groove extended axially and functions as fuel identification means, is formed in the inner diameter side of the front outer cylinder portion 31a. The key groove 54 has a shape to engage with the key portion 13 of the nozzle 1n described above. Since the key portion 13 and the key groove 54 have paired shapes, an injection error or the like of the liquid fuel can be prevented by, for example, defining the shape depending on the liquid fuel. In other words, the key portion 13 is determined to have a shape complying with a type (type, concentration or the like) of the liquid fuel, and the key groove 54 is determined to have a shape complying with the key portion 13, so that only the cartridge 3 which stores a liquid fuel suitable for the fuel cell 2 can be made connectable. Thus, it becomes possible to prevent an operation failure and property degradation due to an injection error of the liquid fuel.
The connection and separation of the above coupler 1 are performed as follows. To connect, the key groove 54 formed in the socket 1s and the key portion 13 formed on the nozzle 1n are aligned, and the nozzle 1n is inserted into the socket 1s. When the nozzle 1n is inserted into the socket 1s, the recessed portion 11d of the nozzle head 11 is first fitted into the tip end of the elastic holder 37 of the socket 1s to form a contacting seal face between them, and the periphery of the liquid fuel passage is sealed before the valves 14 and 40 are brought into an open state.
When the nozzle 1n is further inserted into the socket 1s, the tip end of the rod section 40b of the socket 1s and that of the rod section 14b of the nozzle 1n are contacted. When the nozzle 1n is further inserted into the socket 1s, the valve 40 of the socket 1s retracts to open, the valve 14 of the nozzle 1n retracts to open to establish the liquid fuel passage between them, and the liquid fuel stored in the cartridge 3 is supplied to the fuel storing section 5 of the fuel cell 2.
On the other hand, when the nozzle 1n is removed from the socket 1s, an operation opposite to the above connecting operation is performed. Specifically, when the nozzle 1n is pulled out of the socket 1s, first the nozzle holding mechanism 36 and the peripheral groove 11e of the nozzle head 11 are disengaged. And, when the nozzle 1n is further pulled, the valve 14 of the nozzle 1n is moved to the front end side, and the liquid fuel passage in the nozzle 1n is closed. When the nozzle 1n is further pulled out, the valve 40 of the socket 1s is also moved toward the tip end, and the liquid fuel passage in the socket 1s is closed. Finally, the rod section 14b of the nozzle 1n and the rod section 40b of the socket 1s are separated from each other, and the recessed portion 11d of the nozzle head 11 is also separated from the elastic holder 37 to release the seal, thereby returning to the unconnected state as shown in
The coupler 1 according to the embodiment has a feature that the rod section on the contact side of at least one valve selected from the valve 14 on the side of the nozzle 1n described above and the valve 40 on the side of the socket 1s, namely at least one selected from the rod section 14b and the rod section 40b, is mainly made of the metal member. The valve which is assumed that the rod section of the contact side is mainly made of the metal member is preferable that at least the surface portion of the head section and the rod section (rod section on the rear end side) on the side opposite to the contact side is made of a non-metallic material, and specifically, it is preferably made of a resin material. A case that the rod section 40b of the valve 40 on the side of the socket 1s is mainly made of a metal member is described below.
As shown in
For example, the rod sections 40b and 40c are formed with four projected portions 40d which protrude from the shaft center toward the outer diameter side to form a cross-shaped cross-sectional shape when viewed axially. And, the space between the adjacent projected portions 40d becomes a fuel passage 40e which is a passage for the liquid fuel, and the fuel passage 40e extends axially.
As shown in
The rod formation section 41a which forms the rod section 40b substantially in its state as it is, and for example, has a cross-shaped cross-sectional shape when viewed axially as described above. The root portion of the rod section 40b may be covered by the resin material section 42, and the root portion of the rod section 40b may not be necessarily formed of only the rod formation section 41a. And, the buried section 41b has, for example, a plate shape and arranged mainly in the head section 40a.
On the other hand, the resin material section 42 is formed to cover the buried section 41b of the metal member 41 and forms the head section 40a and the rod section 40c on the rear end side. And, the resin material section 42 may be formed to cover the periphery of the rod formation section 41a at the root portion of the rod section 40b as described above.
Thus, the rod section 40b of the valve 40 is mainly made of the metal member 41, so that the strength can be improved in comparison with the conventional valve made of only the resin material, and deformation or breakage can be suppressed when the socket 1s and the nozzle 1n are connected or separated. And, the rod section 40b is contacted by the liquid fuel only when the socket 1s and the nozzle 1n are connected, namely when the liquid fuel is supplied from the fuel cartridge 3 to the fuel cell 2. In other cases, the rod section 40b is not contacted by the liquid fuel, so that a problem of corrosion does not occur easily even when the rod section 40b is made of the metal member 41.
On the other hand, the portions from the head section 40a to the rear end side, namely the head section 40a and the rod section 40c, are arranged within the socket 1s which is connected to the fuel storing section 5 and the fuel receiving portion 6 and tend to be easily corroded because they are always in contact with the liquid fuel. But since at least the surface portion is determined to be the resin material section 42, easy occurrence of the corrosion problem can be suppressed.
As the above metal member 41, one excelling in fuel resistance such as methanol resistance is preferable. Its preferable examples include SUS304 which is stainless steel containing 18% of chromium and 8% of nickel, SUS316 which is stainless steel containing 18% of chromium, 12% of nickel and molybdenum (Mo) and more excelling in corrosion resistance, and titanium or titanium alloy, but they are not necessarily exclusive.
The surface of the metal member 41, and particularly the surface of the rod formation section 41a, is preferably undergone the surface treatment to improve the fuel resistance such as methanol resistance. Preferable examples of the surface treatment include a passivation treatment, gold coating, fluorine resin coating, etc.
The resin material section 42 is also preferably made of a resin material excelling in fuel resistance such as methanol resistance. Its examples preferably include a general-purpose engineering plastic such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT) or polyacetal (POM), and a super-engineering plastic such as polyphenylene sulfide (PPS), polyether ether ketone (PEEK) or a liquid crystal polymer (LCP).
It is preferable that the buried section 41b of the metal member 41 is provided with, for example, an anchor portion 41c having a large width to suppress it from coming out of the resin material section 42. The anchor portion 41c is not necessarily limited to one having a large width but may be, for example, a circular through hole as shown in
The valve 40 shown in
The valves 40 shown in
The above valve 40 can be produced by, for example, forming the resin material section 42 on the outer periphery of the buried section 41b after the metal member 41 having the rod formation section 41a and the buried section 41b is formed. In addition to a method of integrally forming by pouring a melt of a metal material into a mold, the metal member 41 can be produced by separately producing individual parts and fitting or welding them to bond together.
The cutout portion 41p in the first metal plate 41m has a width (length in a direction perpendicular to the shaft center) which is formed to be similar to or slightly smaller than the thickness of, for example, the second metal plate 41n, and the cutout portion 41q in the second metal plate 41n also has a width which is formed to be similar to or slightly smaller than the thickness of, for example, the first metal plate 41m. And, the cutout portion 41p of the first metal plate 41m and the cutout portion 41q of the second metal plate 41n are mutually press fitted, so that the first metal plate 41m and the second metal plate 41n are fixed by the cutout portions 41p and 41q mutually, and the metal member 41 having a cross-shaped cross-sectional shape when viewed axially can be obtained as shown in
The obtained metal member 41 can be formed to have the resin material section 42, which becomes the head section 40a and the rod section 40c, by forming on, for example, the outer periphery of the buried section 41b to obtain the valve 40. As means for disposing the resin material section 42 on the buried section 41b, for example, an insert molding method can be applied, and specifically, the metal member 41 which is an insert member is loaded into a mold, a melted resin material is injected, and the buried section 41b of the metal member 41 is covered with the melted resin material, which is then cured. Thus, the valve 40 which is an integrated composite member of the metal member 41 and the resin material section 42 can be obtained.
The example that the rod section 40b of the valve 40 is mainly made of the metal member 41 was described above. As described above, the rod section 40b is not necessarily required to be wholly made of the metal member 41 (rod formation section 41a). For example, as shown in
In addition, in the coupler 1 of the embodiment, the rod section 14b in the valve 14 on the side of the nozzle 1n may be mainly made of a metal member instead of having the rod section 40b in the valve 40 on the side of the socket 1s mainly made of the metal member 41. In a case where the rod section 14b in the valve 14 is mainly made of the metal member, it can be configured in substantially the same manner as the case that the rod section 40b in the valve 40 is mainly made of the metal member 41. It is more preferable for the coupler 1 of the embodiment that the rod section 14b in the valve 14 is mainly made of the metal member, and the rod section 40b in the valve 40 is mainly made of the metal member 41 from a viewpoint of improving the reliability.
The fuel cell 2 of the embodiment is described below. The fuel cell 2 of the embodiment is provided with the socket 1s having the valve 40 which has the rod section 40b on the contact side in the above-described coupler 1 mainly made of the metal member 41, the fuel storing section 5 for storing the liquid fuel supplied via the socket 1s, and the fuel battery cell 4 which is an electromotive portion to generate power by using the liquid fuel. The fuel battery cell 4 in the fuel cell 2 of the embodiment is not limited to a particular one, and for example, there is a passive or active type DMFC to which a satellite type cartridge 3 is connected, if necessary.
The fuel cell 2 of the embodiment is described below with reference to an inside vaporization type DMFC.
The fuel battery cell 4 has a membrane electrode assembly (MEA) which has an anode (fuel electrode) having an anode catalyst layer 62 and an anode gas diffusion layer 63, a cathode (oxidant electrode/air electrode) having a cathode catalyst layer 64 and a cathode gas diffusion layer 65, and a proton (hydrogen ion) conductive electrolyte membrane 66 sandwiched between the anode catalyst layer 62 and the cathode catalyst layer 64. Examples of the catalyst contained in the anode catalyst layer 62 and the cathode catalyst layer 64 include a single element of platinum group elements such as Pt, Ru, Rh, Ir, Os, Pd, etc., an alloy containing a platinum group element, and the like.
Specifically, it is preferable to use Pt—Ru, Pt—Mo or the like which has high resistance to methanol and carbon monoxide for the anode catalyst layer 62 and platinum, Pt—Ni or the like for the cathode catalyst layer 64. And, a supported catalyst using a conductive carrier such as carbon material or an unsupported catalyst may be used. Examples of the proton conductive material configuring the electrolyte membrane 66 include a fluorine-based resin (Nafion (trade name, a product of DuPont), Flemion (trade name, a product of Asahi Glass Co., Ltd.) and the like) such as a perfluorosulfonic acid polymer having a sulfonic group, a hydrocarbon-based resin having the sulfonic group, an inorganic substance such as tungstic acid or phosphotungstic acid, and the like. But, they are not used exclusively.
The anode gas diffusion layer 63 superposed on the anode catalyst layer 62 serves to uniformly supply the fuel to the anode catalyst layer 62 and also serves as a power collector of the anode catalyst layer 62. Meanwhile, the cathode gas diffusion layer 65 superposed on the cathode catalyst layer 64 serves to uniformly supply an oxidant to the cathode catalyst layer 64 and also serves as a power collector of the cathode catalyst layer 64. An anode conductive layer 67 is superposed on the anode gas diffusion layer 63, and a cathode conductive layer 68 is superposed on the cathode gas diffusion layer 65.
The anode conductive layer 67 and the cathode conductive layer 68 are configured of, for example, a mesh, a porous film, a thin film or the like which is formed of a conductive metal material such as gold. Rubber O-rings 69 and 70 are interposed between the electrolyte membrane 66 and the anode conductive layer 67 and between the electrolyte membrane 66 and the cathode conductive layer 68, respectively. They prevent the fuel and the oxidant from leaking from the fuel battery cell 4.
For example, a methanol fuel is charged as liquid fuel F into the fuel storing section 5. The fuel storing section 5 is open on the side of the fuel battery cell 4, and the gas selectively permeable membrane 61 is disposed between the opening portion of the fuel storing section 5 and the fuel battery cell 4. The gas selectively permeable membrane 61 is a vapor-liquid separating film which allows the passage of only the vaporized component of the liquid fuel F but does not allow the passage of the liquid component. The component materials of the gas selectively permeable membrane 61 include, for example, a fluorine resin such as polytetrafluoroethylene. The vaporized component of the liquid fuel F means a gas mixture which consists of a vaporized component of methanol and a vaporized component of water when the aqueous methanol solution is used as the liquid fuel F and a vaporized component of methanol when pure methanol is used.
A moisture retaining layer 71 is laminated on the cathode conductive layer 68, and a surface layer 72 is laminated on the moisture retaining layer 71. The surface layer 72 has a function to adjust an introduced volume of air which is an oxidant, and its adjustment is performed by changing the quantity, size and the like of air introduction ports 72a formed in the surface layer 72. The moisture retaining layer 71 plays a role of suppressing water evaporation by partial impregnation of water generated by the cathode catalyst layer 64 and also has a function to promote uniform diffusion of the oxidant to the cathode catalyst layer 64 by uniform introduction of the oxidant into the cathode gas diffusion layer 65. For example, the moisture retaining layer 71 is formed of a member having a porous structure, and its specific component materials include a porous body or the like of polyethylene or polypropylene.
The gas selectively permeable membrane 61, the fuel battery cell 4, the moisture retaining layer 71 and the surface layer 72 are sequentially stacked on the fuel storing section 5, and they are entirely covered with, for example, a stainless steel cover 73 to configure the fuel cell 2. The cover 73 is provided with openings 73a at portions corresponding to the air introduction ports 72a which are formed in the surface layer 72. The fuel storing section 5 is provided with a terrace 5a for receiving a fixture portion 73b of the cover 73, and the terrace 5a is caught by caulking the fixture portion 73b to entirely hold the fuel cell 2 by the cover 73.
According to the fuel cell 2 having the structure described above, the liquid fuel F (e.g., the aqueous methanol solution) in the fuel storing section 5 is vaporized, and the vaporized component is supplied to the fuel battery cell 4 through the gas selectively permeable membrane 61. In the fuel battery cell 4, the vaporized component of the liquid fuel F is diffused by the anode gas diffusion layer 63 and supplied to the anode catalyst layer 62. The vaporized component supplied to the anode catalyst layer 62 causes an internal reforming reaction of methanol expressed by the following formula (1).
CH3OH+H2O→CO2+6H++6e− (1)
When pure methanol is used as the liquid fuel F, steam is not supplied from the fuel storing section 5, so that water produced by the cathode catalyst layer 64 and water in the electrolyte membrane 66 are reacted with methanol to cause the internal reforming reaction expressed by the formula (1), or an internal reforming reaction is caused by another reaction mechanism not requiring water without depending on the above-described internal reforming reaction of the formula (1).
Proton (H+) produced by the internal reforming reaction reaches the cathode catalyst layer 64 through the electrolyte membrane 66. Air (oxidant) introduced through the air introduction ports 72a of the surface layer 72 is diffused into the moisture retaining layer 71, the cathode conductive layer 68 and the cathode gas diffusion layer 65 and supplied to the cathode catalyst layer 64. The air supplied to the cathode catalyst layer 64 causes the reaction expressed by the following formula (2). This reaction causes a power generation reaction involving the generation of water.
(3/2)O2+6H++6e−→3H2O (2)
With the progress of the power generation reaction based on the above-described reaction, the liquid fuel F (e.g., an aqueous methanol solution or pure methanol) in the fuel storing section 5 is consumed. Since the power generation reaction stops when the liquid fuel F in the fuel storing section 5 is exhausted, the liquid fuel is supplied from the cartridge 3 into the fuel storing section 5 at that time or before that. The supply of the liquid fuel from the cartridge 3 is performed with the nozzle 1n of the cartridge 3 connected to the unshown socket 1s of the fuel cell 2 by inserting into it as described above.
The coupler for a fuel cell and the fuel cell of the embodiment were described above, but the coupler for a fuel cell and the fuel cell of the embodiment are not limited to the embodiments described above. It is to be understood that in a practical phase it can be materialized with the component elements modified within the scope of technical idea of the embodiment. And, various embodiments can be made by an appropriate combination of the plural component elements described in the above embodiments. For example, some component elements may be deleted from the whole component elements shown in the embodiments. For example, a passive type DMFC which is under downsizing is suitable as a fuel cell, but its method, mechanism or the like is not limited when it is provided with the socket having a special valve in the coupler for a fuel cell of the embodiment and the liquid fuel is supplied via the socket.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. Indeed, the novel coupler and the novel fuel cell described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the novel coupler and the novel fuel cell described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| P2007-297598 | Nov 2007 | JP | national |
This application is a continuation of prior International Application No. PCT/JP2008/003255, filed on Nov. 11, 2008 which is based upon and claims the benefit of priority from Japanese Patent Application No. 2007-297598, filed on 16 Nov. 2007; the entire contents of all of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2008/003255 | Nov 2008 | US |
| Child | 12780743 | US |
