Patent Publication Number: US-2009233150-A1

Title: Liquid injection device of fuel cell, fuel cell and fuel cartridge

Description:
TECHNICAL FIELD 
     The present invention relates to a liquid injection device of a fuel cell for injecting liquid fuel such as high concentration methanol safely from a cartridge into a small-sized fuel cell used as a built-in power source for mobile devices such as portable telephone, portable audio set, notebook personal computer, and portable game machine, and to a fuel cell and a fuel cartridge. 
     BACKGROUND ART 
     A solid electrolyte type fuel cell has been attracting attention as a power source for portable telephone or the like, and has been intensively developed for practical use. Concepts of development include small size, flat shape, high output by small power consumption, and compatibility for replenishing liquid fuel in a cell main body of any manufacturer by simple operation by using a cartridge easily available wherever to any user. To produce a high output, a fuel of high power generation efficiency is demanded, and a high concentration methanol solution is most hopeful as this fuel. For example, Japanese Patent No. 3413111 proposes a fuel cell using high concentration methanol as fuel. 
     When high concentration methanol solution is used as fuel, the system is not opened but is closed, and auxiliary mechanisms are incorporated inside, such as fuel pump, intake pump and fuel concentration sensor, so that the fuel should be consumed only inside of the battery. Since high concentration methanol has a low boiling point, it is easily evaporated and dissipates, and its vapor may be inhaled by a user. Therefore, it cannot be exposed to an atmosphere from the viewpoint of safety and health. 
     In particular, in a satellite type cartridge, that is, one cartridge possibly used by plural devices, compatibility and prevention of wrong use are important and contradictory problems. 
     However, if a tank in a fuel cell becomes empty during use and when refilling the fuel cell tank with liquid fuel from a cartridge, the system is temporarily opened, by opening a liquid discharge port of the cartridge or opening a liquid injection port of the cell main body, and thus high concentration methanol may escape outside. From the viewpoint of safety and health, the high concentration methanol should never escape outside even when refilling the fuel. Since the fuel is refilled by a user, there is a demand for a mechanism, easily handled by anyone, for refilling the fuel safely and securely without causing liquid leak. 
     DISCLOSURE OF INVENTION 
     The invention has been devised to solve these problems, and it is hence an object thereof to provide a liquid injection device of a fuel cell, a fuel cell, and a fuel cartridge having compatibility, and capable of injecting liquid such as high concentration methanol safely in a fuel cell, without causing liquid leak, by simple operation. 
     A liquid injection device of a fuel cell which inserts a cartridge nozzle in an injection port of a fuel cell main body, pushes in the nozzle to open both a valve of the nozzle and a valve of the injection port, and injects liquid into the fuel cell from the cartridge through the nozzle and the injection port, the device comprising: 
     a protrusion provided in either the injection port or the cartridge nozzle; and 
     a groove provided in either the injection port or the cartridge nozzle so as to be fitted with the protrusion, fitted with the protrusion when the cartridge nozzle is inserted into the injection port, and guiding the protrusion when the cartridge nozzle is pushed into an axial direction. 
     A fuel cell having an injection port into which a nozzle of a fuel cartridge is inserted for replenishing liquid fuel, comprising: 
     a bayonet coupler element provided in an inner peripheral wall which defines the injection port, fitted to an outer circumference of the nozzle when the nozzle of the fuel cartridge is inserted into the injection port, and guiding the nozzle when the nozzle is further pushed in an axial direction. 
     A fuel cartridge provided with a nozzle to be inserted into an injection port of a fuel cell for replenishing liquid fuel, comprising: 
     a bayonet coupler element provided in an outer peripheral wall of the nozzle, fitted to an inner circumference of the injection port when the nozzle is inserted into the injection port of the fuel cell, and guided into the injection port when the nozzle is further pushed in an axial direction. 
     In the invention, the cartridge nozzles are different at least in one of the number, shape and position of protrusions or grooves, to individually identify contained liquids. As a result, the cartridges can be individually identified. For example, on the basis of the number, shape and position of protrusions or grooves, the type and concentration of the liquid contained in the cartridge can be identified. Specifically, the means for varying the protrusion or groove shape may include variation of single or plural protrusions or grooves in a circumferential direction (see  FIGS. 19A to 26D ). The means for varying the protrusion or groove position may include symmetrical configuration of plural protrusions or grooves with respect to a central axis of the cartridge (see  FIGS. 21A to 21C ,  FIGS. 22A to 22C ,  FIGS. 25A to 25D , and  FIGS. 26A to 26D ), or asymmetrical configuration (see  FIGS. 23A to 23D  and  FIGS. 24A to 24D ). 
     A cartridge nozzle of male type may be combined with a liquid injection port of female type of the cell main body (see  FIGS. 1 to 5 ), or, to the contrary, a cartridge nozzle of female type may be combined with a liquid injection port of male type of the cell main body (see  FIGS. 17 and 18 ). The cartridge nozzle of male type can be easily identified from outside by its protrusion or groove, but it is exposed to outer circumference and thus may be weak structurally. In particular, when a protrusion is formed on the male type cartridge nozzle, the strength must be reinforced by using a metal material or the like so as not to be hit and broken by other members. The cartridge nozzle of female type has the protrusion or groove provided inside and is generally rigid, and there is no problem in strength if made of resin, but it is hard to identify the protrusion or groove from outside. In particular, when a groove is formed in the cartridge nozzle of female type, it is more difficult to identify. Hence, preferably, a groove is formed in the cartridge nozzle of male type, and a protrusion is formed in the cartridge nozzle of female type. 
     In the invention, the groove and protrusion may be provided at either the cell main body side or the cartridge side, but most preferably the protrusion is formed inside of the injection port of the cell main body side, and the groove is formed on the nozzle outer circumference of the cartridge side (see  FIGS. 7A to 10B ). This is because the protrusion at the inner circumference of the injection port does not project outward, and thus it is hardly hit or broken as compared with the protrusion on the outer circumference of the cartridge nozzle, and it is less likely to be damaged. 
     The groove is preferably provided with a lock function for guiding the protrusion in the axial direction, and displacing and guiding the protrusion in the circumferential direction so that the cartridge nozzle may be locked in the liquid injection port. As a result, the nozzle is not detached from the injection port while injecting the liquid, and the liquid can be injected into the fuel cell safely and securely. 
     In the invention, near the terminal end of the groove, there is preferably a small protrusion (bud) projecting from the side peripheral wall of the groove and ridden over by the protrusion guided along the groove (see  FIGS. 7A and 9 ). As a result, the fitting is not easily detached, and the user can feel the click (locking sense) of riding over the small protrusion such as fitting of cap and bottle at his/her fingertip, and completion of connection can be securely felt physically. 
     Preferably, wet ends of the injection port and cartridge nozzle contacting with the liquid are made of resin, and dry ends of the injection port and cartridge nozzle not contacting with the liquid are made of materials stiffer than resin. The wet ends are made of rigid resin or plastic not causing swelling or crack in contact with high concentration methanol, such as polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), liquid crystal polymer (LCP), and polyacetal (POM). 
     If a metal material is used in a portion contacting with high concentration methanol, cations dissolved in a methanol solution have adverse effects on battery performance, and therefore a nonmetallic material such as resin material is used at the wet ends. On the other hand, the dry ends are made of metal or alloy having corrosion resistance to high concentration methanol, such as austenitic stainless steel (SUS304, etc.), titanium or titanium alloy, nickel alloy, nickel-chromium alloy, nickel-chromium-molybdenum alloy, and aluminum alloy. Using iron or copper excellent in machinability, after machining, the resin may be coated with a metal of high corrosion resistance. In particular, when the protrusion is provided in the dry ends, the protrusion may be made of a metal material. Accordingly, the strength of the protrusion can be improved, and an excellent durability is obtained in repeated attaching and detaching strokes of the cartridge (nozzle). 
     The groove is formed of a plurality of grooves distributed from the axial center of the injection port or cartridge nozzle, and along the inner circumference of the injection port or the outer circumference of the cartridge nozzle, terminal ends are preferably rotated and displaced by 45 degrees to 90 degrees in the circumferential direction with respect to the starting ends. The number of grooves is preferably 2 or 3, but may be 1 or 4. The profile of the groove is preferably in a figure of L, a figure of inverted L, a figure of J, a figure of inverted J, or oblique and straight (spiral linear), in the shape of two-dimensional projection plane from the side direction (see  FIGS. 12A ,  12 B,  14 A, and  14 B). By defining the profile in such a shape, the cartridge nozzle is not easily detached from the injection port while injecting fuel, the safety is improved, the sealing performance of the groove and protrusion is improved, and the liquid leak prevention effect is further enhanced. 
     The injection port is provided behind the protrusion or groove so as to contact with the leading end of the nozzle when the cartridge nozzle is inserted into the injection port, and is further desired to have an elastic holder which is deformed elastically while keeping sealing performance when the nozzle is further pushed in the axial direction (see  FIGS. 1 to 5 ,  17 , and  18 ). The elastic holder may be manufactured by using thermoplastic synthetic rubber or elastomer of various hardness levels. By pushing in the nozzle, the elastic holder is deformed elastically to seal tightly with the nozzle leading end, and then a valve of the cartridge nozzle side, and a valve of the injection port of the cell main body side are both opened, so that the liquid fuel can flow from the cartridge side to the cell main body side. The elastic holder is preferred to be of bellows shape so as to assure a liquid passage when the shape of the holder is compressed by pushing of the nozzle, and to be deformed elastically while keeping a proper shape for the liquid passage (see  FIGS. 6A and 6B ). 
     The opening sequence of the valve of the cartridge nozzle side and the valve of the injection port of the cell main body side, that is, the opening and closing order of the valves depends on the relative magnitude of spring coefficients of compression springs biasing the valves. When the spring coefficient of the compression spring of the cartridge nozzle side is greater than that of the cell main body side, the valve of the cell main body side opens first, and then the valve of the cartridge side opens later. On the other hand, when the spring coefficient of the compression spring of the cell main body side is greater than that of the cartridge nozzle side spring, the valve of the cartridge nozzle side opens first, and then the valve of the cell main body side opens later. 
     In the invention, it is further desired to have a tapered holding groove formed in the valve body of the cartridge nozzle valve, and a seal ring of irregular section held by this holding groove (see  FIGS. 16 to 18 ). By forming in such a shape, the seal ring is not easily detached from the valve body. 
     It is also desired to have a first needle disposed in the passage of the cartridge nozzle as part of the valve body of the cartridge nozzle valve, and having a convex or concave leading end, and a second needle disposed in the passage of the injection port as part of the valve body of the injection port valve, and having a convex or concave leading end to be fitted with the leading end of the first needle (see  FIGS. 1 ,  2 ,  17 , and  18 ). In the liquid injection device of the invention, to prevent leakage of liquid and vapor, the passage of the cartridge nozzle and the passage of the cell main body injection port are made as narrow as possible, and a thin and slender needle is inserted in each of the narrow passages. As a result, the abutting areas of needle leading ends are very small, and the both needles tend to come offset when pushing the nozzle. If pushed continuously in the offset state, a passage may not be assured. Hence, the needle leading end of one side is convex, and the needle leading end of the other side is concave, so that the former can fit into the latter securely. As a result, offset is prevented, and the both needles are designed to operate coaxially. 
     Preferably, the first and second needles have concave grooves extending in the longitudinal direction, a first passage for passing the liquid is formed between the recess in the first needle and the inner peripheral wall of the cartridge nozzle, and a second passage for passing the liquid is formed between the recess in the second needle and the inner peripheral wall of the injection port (see  FIG. 15 ). Instead of the recess, a groove may be cut in the needle. A similar recess or groove is preferably formed in a guide pin projecting from the valve body of the opposite side of the needle (see  FIGS. 1 and 15 ). 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an internal see-through sectional view of a liquid injection device of a fuel cell of the invention. 
         FIG. 2  is an internal see-through sectional view of a liquid injection device in a first stage having a cartridge nozzle (male type having groove in outer circumference) inserted in an injection port (female type having protrusion in inner circumference) of a fuel cell. 
         FIG. 3  is an internal see-through sectional view of a liquid injection device in a second stage having a cartridge nozzle pushed into an injection port of a fuel cell. 
         FIG. 4  is an internal see-through sectional view of a liquid injection device in a third stage having a cartridge nozzle pushed further into an injection port of a fuel cell. 
         FIG. 5  is an internal see-through sectional view of a liquid injection device in a fourth stage having a cartridge nozzle pushed further into an injection port of a fuel cell. 
         FIG. 6A  is an outline view of an elastic holder. 
         FIG. 6B  is a sectional view of the elastic holder. 
         FIG. 7A  is a plan view of a cartridge nozzle. 
         FIG. 7B  is a side view of the cartridge nozzle of  FIG. 7A . 
         FIG. 8  is a longitudinal sectional view of the cartridge nozzle. 
         FIG. 9  is a magnified sectional view of a groove formed in an outer circumference of the cartridge nozzle. 
         FIG. 10A  is a plan sectional view of an injection port of a fuel cell tank side. 
         FIG. 10B  is a longitudinal sectional view of the injection port of  FIG. 10A . 
         FIG. 11A  is a plan view of a cartridge nozzle (male type having protrusion in outer circumference) in another embodiment. 
         FIG. 11B  is a side view of the cartridge nozzle of  FIG. 11A . 
         FIG. 12A  is a plan view of an injection port of a fuel cell side (female type having groove in inner circumference) in another embodiment. 
         FIG. 12B  is a longitudinal sectional view of the injection port of  FIG. 12A . 
         FIG. 13A  is a plan view of a cartridge nozzle (male type having protrusion in outer circumference) in another embodiment. 
         FIG. 13B  is a side view of the cartridge nozzle of  FIG. 13A . 
         FIG. 14A  is a plan view of an injection port of a fuel cell side (female type having groove in inner circumference) in another embodiment. 
         FIG. 14B  is a longitudinal sectional view of the injection port of  FIG. 14A . 
         FIG. 15  is a sectional view of a needle of a coupler valve. 
         FIG. 16  a partially magnified sectional view of a valve portion of a cartridge in another embodiment. 
         FIG. 17  is an internal see-through sectional view of a liquid injection device of a fuel cell in another embodiment of the invention. 
         FIG. 18  is an internal see-through sectional view of a liquid injection device in another embodiment when it is ready to inject liquid by connecting a cartridge nozzle into an injection port of a fuel cell. 
         FIG. 19A  is a plan sectional view of a cell main body side coupler (female type injection port) having a protrusion in an inner circumference. 
         FIG. 19B  is a plan sectional view of a cell main body side coupler (female type injection port) having a protrusion in an inner circumference. 
         FIG. 19C  is a plan sectional view of a cartridge side coupler (male type cartridge nozzle) having a groove in an outer circumference. 
         FIG. 19D  is a plan sectional view of a cartridge side coupler (male type cartridge nozzle) having a groove in an outer circumference. 
         FIG. 20A  is a plan sectional view of a cell main body side coupler (male type injection port) having a groove in an outer circumference. 
         FIG. 20B  is a plan sectional view of cell main body side coupler (male type injection port) having groove in an outer circumference. 
         FIG. 20C  is a plan sectional view of a cartridge side coupler (female type cartridge nozzle) having a protrusion in an inner circumference. 
         FIG. 20D  is a plan sectional view of a cartridge side coupler (female type cartridge nozzle) having a protrusion in an inner circumference. 
         FIG. 21A  is a plan sectional view of a cell main body side coupler having a pair of right and left symmetrical protrusions in an inner circumference. 
         FIG. 21B  is a plan sectional view of a cell main body side coupler having a pair of right and left symmetrical protrusions in an inner circumference. 
         FIG. 21C  is a plan sectional view of a cell main body side coupler having a pair of right and left symmetrical protrusions in an inner circumference. 
         FIG. 22A  is a plan sectional view of a cartridge side coupler having a pair of right and left symmetrical grooves in an outer circumference. 
         FIG. 22B  is a plan sectional view of a cartridge side coupler having a pair of right and left symmetrical grooves in an outer circumference. 
         FIG. 22C  is a plan sectional view of a cartridge side coupler having a pair of right and left symmetrical grooves in an outer circumference. 
         FIG. 23A  is a plan sectional view of a cell main body side coupler having a pair of asymmetrical protrusions in an inner circumference. 
         FIG. 23B  is a plan sectional view of a cell main body side coupler having a pair of asymmetrical protrusions in an inner circumference. 
         FIG. 23C  is a plan sectional view of a cell main body side coupler having a pair of asymmetrical protrusions in an inner circumference. 
         FIG. 23D  is a plan sectional view of a cell main body side coupler having a pair of asymmetrical protrusions in an inner circumference. 
         FIG. 24A  is a plan sectional view of a cartridge side coupler having a pair of asymmetrical grooves in an outer circumference. 
         FIG. 24B  is a plan sectional view of a cartridge side coupler having a pair of asymmetrical grooves in an outer circumference. 
         FIG. 24C  is a plan sectional view of a cartridge side coupler having a pair of asymmetrical grooves in an outer circumference. 
         FIG. 24D  is a plan sectional view of a cartridge side coupler having a pair of asymmetrical grooves in an outer circumference. 
         FIG. 25A  is a plan sectional view of a cell main body side coupler having three symmetrical protrusions in an inner circumference. 
         FIG. 25B  is a plan sectional view of a cell main body side coupler having three symmetrical protrusions in an inner circumference. 
         FIG. 25C  is a plan sectional view of a cell main body side coupler having three symmetrical protrusions in an inner circumference. 
         FIG. 25D  is a plan sectional view of a cell main body side coupler having three symmetrical protrusions in an inner circumference. 
         FIG. 26A  is a plan sectional view of a cartridge side coupler having three symmetrical grooves in an outer circumference. 
         FIG. 26B  is a plan sectional view of a cartridge side coupler having three symmetrical grooves in an outer circumference. 
         FIG. 26C  is a plan sectional view of a cartridge side coupler having three symmetrical grooves in an outer circumference. 
         FIG. 26D  is a plan sectional view of a cartridge side coupler having three symmetrical grooves in an outer circumference. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Referring now to the accompanying drawings, preferred embodiments of the invention will be described below. 
     A liquid injection device of a fuel cell of the invention is a combination of a cartridge  1  and an injection port  20  of a fuel cell main body  100  side as shown in  FIG. 1 . In addition, as shown in  FIGS. 2 to 5 , a cartridge nozzle  6  as a cartridge side coupler is inserted into a liquid inlet  20   a  of the injection port as a main body side coupler, and high concentration methanol solution as liquid fuel is supplied into a tank (not shown) in the fuel cell main body. 
     The cartridge  1  includes a container  2  for defining a containing space  3  of high concentration methanol as liquid fuel, a cartridge base  4  provided so as to surround an opening  2   a  formed at one end side of the container  2 , and a cartridge nozzle  6  provided at the container opening  2   a . The container  2  may be formed in various shapes, including cylinder, spindle, flat tube, and square tube. The cartridge base  4  and the cartridge nozzle  6  are integrally molded, and the cartridge nozzle  6  is extended outward from the cartridge base  4 . The integrally molded body of base  4  and nozzle  6 , the container opening  2   a , and a plug  7  are mutually sealed by a rubber packing  5  of U-section. 
     The cartridge nozzle  6  has a nozzle main body  6   b , a valve  8 , the plug  7 , a compression spring  10 , and a seal ring  11 . In the outer circumference of the nozzle main body  6   b , a groove  60  is cut as a bayonet coupler element. A needle (valve stem)  8 B of the valve  8  is inserted in an internal passage of the nozzle main body  6   b . The plug  7  surrounds a valve body  8   f  of the valve  8 , and defines a valve compartment space  9 . The compression spring  10  biases the valve body  8   f  toward a valve seat  4   a . The seal ring  11  is held in a holding groove  8   h  of the valve body  8   f , and is pushed against the valve seat  4   a  by the biasing force of the compression spring  10 . When the seal ring  11  is forcibly separated from the valve seat  4   a , a liquid inlet  6   c  is opened, and the liquid flows into a liquid outlet  6   a.    
     The plug  7  is formed like a hat or cup shape, and a flange  7   b  is detachably held in the cartridge base  4  by way of the rubber packing  5 . The plug  7  is a thin wall resin (made of, for example, PEEK), and has a certain flexibility. To assemble these components, the valve  8  is incorporated in the plug  7 , the flange  7   b  of the plug  7  is fitted into the rubber packing  5  adhered to the cartridge base  4 , and the cartridge base  4  is adhered to the container opening  2   a , and/or crimped and/or screwed. 
     The valve  8  has the valve body  8   f , the needle (valve stem)  8   b , and a guide pin  8   a . The holding groove  8   h  is formed at the front end of the valve body  8   f  (lower side in the drawing), and the seal ring  11  is held by this holding groove  8   h . The needle  8   b  is projecting like needle or bar from the front end side of the valve body  8   f  (lower side in the drawing). The needle  8   b  functions as a valve stem, and is elevatably inserted in the passage in the nozzle  6 . The length of the needle  8   b  is nearly equal to the overall length of the passage of the nozzle  6 . However, while the cartridge  1  is not connected to the cell main body  110 , that is, in non-use state, a preferred length is designed such that a leading end  8   c  of the needle is slightly withdrawn from the liquid outlet  6   a  of the nozzle. It is hence effective to avoid damage of the needle leading end  8   c , prevent invasion of foreign matter such as dust into the nozzle passage from the liquid outlet  6   a , and prevent accidental opening of the valve. 
     The guide pin  8   a  projects from the rear end of the valve body  8   f  (upper side in the drawing) toward the container  2 , and protrudes into the liquid storage space  3  at the container side by way of a hole  7   c  in the upper center of the plug  7 . A plurality of communication holes  7   d  are opened in an upper plate  7   a  of the plug, so that the liquid fuel flows into the valve compartment space  9  from the liquid storage space  3  through the communication holes  7   c ,  7   d.    
     A stopper  8   d  is provided at the rear end of the valve body  8   f , and an ascending stroke is defined for allowing the valve body  8   f  to move in the axial direction (Z-direction). That is, when a force exceeding the biasing force of the compression spring  10  is loaded to the valve body  8   f , (the seal ring  11  is separated from the valve seat  4   a , the liquid inlet  6   c  is released, and the valve compartment space  9  communicates with the liquid outlet  6   a  of the nozzle,) the valve body  8   f  is not elevated limitlessly, but the stopper  8   d  abuts against the upper plate  7   a  of the plug, so that the elevation of the valve body  8   f  is stopped. 
     The compression spring  10  is made of stainless steel wire rod for spring SUS304-WPB of 4 mm in diameter specified in JIS G 4314, electroplated with pure gold (purity 99.9%) having corrosion resistance to high concentration methanol, and its spring coefficient is adjusted to a predetermined magnitude. Other base materials of the compression spring  10  include stainless steel wire for spring (SUS316-WPA), stainless steel strip for spring (SUS631J1-WPC), beryllium steel for spring (JIS G 3130 C1720W), phosphor bronze (JIS C 3130 C5191W), titanium wire material, and other corrosion resistant metal materials. The plating materials include, aside from gold (Au), platinum (Pt), rhodium (Rh), and titanium capable of forming a rigid oxide film, but other various nonmetallic materials may also be used. Such examples include carbon, polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), and other resins excellent in methanol resistance, and these resins may be used as compression spring wire materials. As a nonmetallic coating layer, carbon (for example, diamond-like carbon coating (DLCC)), fluorine, and other resin coating may be used. As a result, metallic cations are not dissolved from the liquid ends contacting with high concentration methanol solution, and deterioration of battery characteristics due to entry of cations can be prevented. One end of the compression spring  10  is affixed to the inside of the upper plate  7   a  of the plug, and the other end thereof is affixed to the small flange of the valve body  8   f.    
     The seal ring  11  is made of thermoplastic synthetic rubber or elastomer not swelling or dissolving in high concentration methanol, and is formed as an O-ring of circular section. The seal ring  11  is fitted into the holding groove  8   h  of the valve body  8   f.    
     The injection port  20  of the fuel cell main body side will be explained below. 
     The injection port  20  includes an upper member  21 , an intermediate member  22 , a lower member  23 , a rubber holder  25 , a valve  26 , a compression spring  27 , a seal ring  28 , and a plurality of protrusions  30  as bayonet coupler elements(key-key way coupling joint elements). The upper member  21 , intermediate member  22 , and lower member  23  are nearly the same in diameter, and are joined coaxially. The upper member  21  is engaged with one end of the intermediate member  22 , and the lower member  23  is engaged with the other end of the intermediate member  22 . The upper member  21 , intermediate member  22 , and lower member  23  are integrated into an assembly, which is screwed into a fuel cell main body (not shown), and the entire structure is buried in the fuel cell main body. Inside the fuel cell main body (not shown), a fuel tank is provided, and the valve compartment space  29  defined by the lower member  23  and the intermediate member  22  communicates with the fuel tank through a hole  23   a.    
     The liquid inlet  20   a  of the injection port is opened to the upper end of the upper member  21  where becoming flush with the outer plane of the cell main body  100 . In the inner circumference of the upper member  21 , two opposing protrusions  30  are provided, each projecting to the liquid inlet  20   a . These two protrusions  30  function as bayonet coupler elements (key coupling joint elements), and are formed in position and shape to be coupled onto two grooves  60  in the nozzle outer circumference at the cartridge side. 
     As shown in  FIGS. 6A and 6B , the rubber holder  25  as an elastic holder has a bellows section  25   c  in the middle of an upper part  25   a  and a lower part  25   b . The bellows section  25   c  is undulated like ring or spiral so as to keep the passage for passing the liquid after compressive deformation. As a result, the methanol solution passes through the bellows section  25   c  smoothly and flows promptly, and the liquid can be injected in a short time without allowing leak. The rubber holder  25  is formed like a ring, its base end is fitted into the recess of the intermediate member  22 , and its leading end  25   a  is extending toward the liquid inlet  20   a . The diameter of the rubber holder leading end  25   a  is nearly the same as that of the cartridge nozzle  6 . The rubber holder  25  is made of thermoplastic synthetic rubber having a hardness defined in a desired value range. When the nozzle  6  comes in contact with the rubber holder leading end  25   a , the leading end  25   a  is deformed (compressed) elastically, and the nozzle  6  can be displaced. 
     The valve  26  includes a valve body  26   f , a guide pin  26   a , a needle  26   b , a stopper  26   d , a compression spring  27 , a seal ring  28 , and a valve seat  22   a . The seal ring  28  of the valve body  26   f  biased by the compression spring  27  is pressed by the valve seat  22   a , and in this state the valve compartment space  29  is shut off from the liquid inlet  20   a . When the pressing force from the nozzle size becomes larger than the biasing force of the compression spring  27 , the seal ring  28  is separated from the valve seat  22   a , and the valve compartment space  29  communicates with the liquid inlet  20   a.    
     The needle  26   b  is extended toward the liquid inlet  20   a  from the front end of the valve body  26   f  (upper side in the drawing). The principal part of the needle  26   b  is surrounded by the rubber holder  25 . A leading end  26   c  of the needle is recessed to be fitted with the protruding needle leading end  8   c  of the cartridge nozzle side valve. When the needles  8   b ,  26   b  are brought closer butt to butt, if the abutting area is small, the needles are pushed in an offset state, and the existing passage may be disturbed. To prevent offset of the needles  8   b ,  26   b , the needle leading end  8   c  of the cartridge nozzle side is formed in a convex shape, and the needle leading end  26   c  of the injection port side is formed in a concave shape, so that the both can be engaged with each other securely. 
     The guide pin  26   a  is extended toward the fuel tank (not shown) by way of the hole  23   c  of the lower member  23 . A stopper  26   d  is provided in the rear end of the valve body  26   f  (lower side in the drawing), and an ascending stroke is defined so as to allow the valve body  26   f  to move in the axial direction. That is, if a force larger than the biasing force of the compression spring  27  is applied to the valve body  26   f , the seal ring  28  is separated from the valve seat  22   a , and the valve compartment space  29  is opened to communicate with the liquid inlet  20   a . However, the valve body  26   f  is not elevated without limitation, but the stopper  26   d  hits against the bottom of the lower member  23 , and the ascending motion of the valve body  26   f  is stopped. 
     A concave groove  38  is formed on the outer circumference of the needles  8   b ,  26   b , and the guide pins  8   a ,  26   a , as shown in  FIG. 15 , along the longitudinal axis, and a passage for passing liquid fuel is formed between inner walls of the nozzle  6 . In the case of a coupler for a portable device, the entire structure needs to be formed in a small size, and thus it is hard to assure a passage. Accordingly, aside from the communication holes  7   d ,  23   a , grooves or recesses for passage are formed in these valve elements  8   a ,  8   b ,  26   a ,  26   b  to cover for shortage of passages.  FIG. 15  shows four concave grooves  38  formed in the valve elements  8   a ,  8   b ,  26   a ,  26   b , but 1 to 3 grooves or 5 or more grooves may be formed. 
     The material of the container  2 , the cartridge base  4 , the cartridge nozzle  6 , the plug  7 , the valve bodies  8   f ,  26   f , the intermediate member  22 , and the lower member  23  is PEEK. The material of the upper member  21  and the ring  24  is stainless steel (SUS304). The material of the packing  5 , the seal rings  11 ,  28 , and the rubber holder  25  is thermoplastic synthetic rubber adjusted in hardness (EDPM 30 degrees, 50 degrees). 
     First Embodiment 
     Referring now to  FIGS. 7A to 10B , a bayonet coupler structure (key-key way coupling joint) consists of a cartridge and a cell main body of a first embodiment will be described below. 
     In the first embodiment, a groove  6   g  is provided in the outer circumference of a male type cartridge nozzle  6 , and the protrusion  30  is provided in the inner circumference of a female type injection port  20  of the cell main body side. The cartridge nozzle  6  as a bayonet coupler element (key way coupling element) has two inverted L-figure grooves  60  provided in the outer circumference as shown in  FIGS. 7A ,  7 B, and  8 . The grooves  60  have protrusion insertion ports distributed by the 180-degree axial center as shown in  FIG. 7A , and are formed in an inverted L figure (the shape on two-dimensional projection plane from the side) rotated and displaced by about 90 degrees clockwise in the circumferential direction when extended from the protrusion insertion ports in the axial direction as shown in  FIG. 7B . 
     A bud  6   p  of a small protrusion is provided in the lateral wall near a groove terminal end  6   e  as shown in  FIG. 9 . The protrusion  30  being guided along the groove  60  rides over the bud  6   p , and the user can feel the click (key locking sense of touch) of riding over the small protrusion like insetting of cap and bottle at his/her fingertip, and physically understands that the connection operation is finished. In the drawing, the bud  6   p  is provided in the upper side lateral wall, but may be provided in the lower side lateral wall, or both upper and lower side lateral walls. 
     The injection port  20  as a bayonet coupler element (key coupling element) has two protrusions  30  in the inner circumference as shown in  FIGS. 10A and 10B . The protrusions  30  are distributed by the 180-degree axial center as shown in  FIG. 1A , and are formed in the shape and size corresponding to the protrusion insertion ports (see  FIG. 8 ) of the groove  60  as shown in  FIG. 10B . 
     The protrusions  30  are fitted into the protrusion insertion ports of the grooves  60 , and by sliding the cartridge nozzle  6  in the axial direction and rotating 90 degrees clockwise, the cartridge nozzle  6  and the injection port  20  are connected with each other. 
     Referring next to  FIGS. 2 to 5 , the operation of injecting liquid fuel into the female type injection port of the cell main body from the male type cartridge will be explained. 
     The cartridge nozzle  6  is inserted into the liquid inlet  20   a  of the injection port, the protrusion  30  of the injection port side is insetted with the groove  60  of the cartridge nozzle side, the nozzle  6  is moved linearly in the axial direction, and is moved in the circumferential direction. At this position, as shown in  FIG. 2 , the leading end of the nozzle  6  is abutting against the rubber holder leading end  25   a  (when the nozzle is inserted by 2.7 mm, it comes in contact with the rubber holder leading end  25   a ). 
     Next, when the nozzle  6  is slightly pushed in the axial direction (and circumferential direction), as shown in  FIG. 3 , the rubber holder leading end  25   a  is deformed elastically (compressed) and the needle leading end  8   c  of the cartridge side valve abuts against the needle leading end  26   c  of the injection port side valve (when the rubber holder is compressed by 0.5 mm, the valve needle ends  8   c  and  26   c  come in contact with each other). 
     By further pushing the nozzle  6  in the axial direction (and circumferential direction), the entire rubber holder  25  is compressed, the entire valve body of the cell main body side valve  26  is pushed down while resisting the biasing force of the compression spring  27 , and the seal ring  28  is separated from the valve seat  22   a . When pushed in to the bottom dead center until the stopper  26   d  comes in contact with the bottom plate of the injection port lower member  23 , as shown in  FIG. 4 , the cell main body side valve  26  is opened to the full (when the rubber holder is compressed by 1.0 mm, the cell main body side valve  26  is opened fully). 
     By further pushing the nozzle  6  in the axial direction, the entire valve body of the cartridge side valve  8  is pushed up while resisting the biasing force of the compression spring  10 , and the seal ring  11  is separated from the valve seat  4   a . When pushed in to the top dead center until the stopper  8   d  abuts against the upper plate  7   a  of the plug, as shown in  FIG. 5 , the cartridge side valve  8  is opened to the full (when the rubber holder is compressed by 1.5 mm, the cartridge side valve  8  is opened fully). 
     In this manner, by pushing the cartridge nozzle  6 , the cell main body side rubber holder  25  is deformed elastically, both the cartridge nozzle side valve  8  and the cell main body side valve  26  are opened, and the liquid fuel flows from the cartridge side to the cell main body side. The opening sequence of the cartridge side valve  8  and the cell main body side valve  26 , that is, the opening and closing order of the valves depends on the relative magnitude of spring coefficients of the compression springs  10 ,  27  biasing the valves. When the spring coefficient of the compression spring  10  of the cartridge side is greater than the spring coefficient of the compression spring  27  of the cell main body side as in this embodiment, the cell main body side valve  26  opens first, and then the cartridge side valve  8  opens later. On the other hand, when the spring coefficient of the compression spring  27  of the cell main body side is greater than the spring coefficient of the compression spring  10  of the cartridge side, the cartridge side valve  8  opens first, and then the cell main body side valve  26  opens later. 
     According to the device of the embodiment, as described above, both the cartridge side and the cell main body side are sealed tightly. Therefore, there is no risk of liquid leak or vapor escape, the cartridge can be connected safely and securely to the injection port of the fuel cell easily by any user, and the liquid fuel can be injected into the fuel cell tank. Since the protrusion is provided inside of the injection port of the cell main body, it does not come in contact with other members, and is not broken or damaged, and it can be use for a long period of time without damage. 
     Second Embodiment 
     Referring now to  FIGS. 11A ,  11 B,  12 A, and  12 B, the structures of a cartridge and a cell main body coupler of a second embodiment will be described below. 
     In the second embodiment, a protrusion  62  is provided in a cartridge nozzle  6 A, and a groove  32  is provided in an injection port  20 A of the cell main body side. The cartridge nozzle  6 A as a bayonet coupler element (key coupling element) has two protrusions  62  provided in the outer circumference as shown in  FIG. 11A . The protrusions  62  are distributed by the 180-degree axial center in a nozzle main body  61  as shown in  FIG. 11A , and provided in the outer circumference near the leading end of the nozzle main body  61  as shown in  FIG. 15B . 
     The injection port  20 A of the cell main body side as a bayonet coupler element (key way coupling element) has two grooves  32  in the inner circumference as shown in  FIG. 12A . The grooves  32  have protrusion insertion ports distributed by the 180-degree axial center as shown in  FIG. 12A , and are formed in an L figure (the shape on two-dimensional projection plane from the side) rotated and displaced by about 90 degrees clockwise in the circumferential direction after extended from the protrusion insertion ports in the axial direction as shown in  FIG. 12B . 
     By such a bayonet coupler structure (structure of key-key way coupling joint), the cartridge nozzle is not easily detached from the injection port during fuel injection, the safety is increased, and the sealing performance of the grooves and protrusions is not deteriorated, so that the liquid leak preventive effect is enhanced. 
     Third Embodiment 
     Referring now to  FIGS. 13A ,  13 B,  14 A, and  14 B, the structures of a cartridge and a cell main body coupler of a third embodiment will be described below. 
     In the third embodiment, a protrusion  63  is provided in a cartridge nozzle  6 B, and a groove  33  is provided in an injection port  20 B of the cell main body side. The cartridge nozzle  6 B as a bayonet coupler element (key coupling element) has three protrusions  63  provided in the outer circumference as shown in  FIG. 13A . The protrusions  63  are distributed by the 120-degree axial center in the nozzle main body  61  as shown in  FIG. 13A , and provided in the outer circumference near the leading end of the nozzle main body  61  as shown in  FIG. 13B . 
     The injection port  20 B of cell main body side as a bayonet coupler element (key way coupling element) has the three grooves  33  in the inner circumference as shown in  FIG. 14A . The grooves  33  have protrusion insertion ports distributed by the 120-degree axial center as shown in  FIG. 14A , and are formed in an oblique linear shape or spiral linear shape (the shape on two-dimensional projection plane from the side) rotated and displaced by about 45 degrees clockwise in the circumferential direction after extended from the protrusion insertion ports in the axial direction as shown in  FIG. 14B . 
     Also by such a bayonet coupler structure (structure of key-key way coupling joint), the cartridge nozzle is not easily detached from the injection port during fuel injection, the safety is increased, and the sealing performance of the grooves and protrusions is not deteriorated, so that the liquid leak preventive effect is enhanced. 
     Referring to  FIG. 16 , a valve of a device  1 A in another embodiment will be described. 
     In the liquid injection device  1 A of the embodiment, a cartridge side valve  8 A is improved. That is, the base end of a seal ring holding groove  81  is smaller in diameter than the leading end, and a seal ring  11 A of irregular section is fitted thereto. The cross sectional shape of the seal ring  11 A is, for example, substantially triangular, so that the seal ring  11 A may not be easily detached from the valve body  8   f . When this seal ring holding groove  81  is formed in a taper, and the seal ring  11 A has an irregular tapered sectional shape corresponding to this tapered surface, the seal ring  11 A does not easily slip out of the valve body  8   f.    
     Although not shown, the same effects as described above are obtained when the seal ring holding groove of the cell main body side valve  26  is formed in a taper so that the base end side is smaller in diameter than the leading end side, and an O-ring  28  to be fitted thereto is formed as a seal ring of irregular section (see a seal ring  28 A in  FIGS. 17 and 18 ). 
     Fourth Embodiment 
     Referring to  FIGS. 17 and 18 , a liquid injection device having the structures of a cartridge and a cell main body coupler in a fourth embodiment will be described. 
     In the liquid injection device of the embodiment, a plurality of protrusions  130  are provided in the inner circumference of a nozzle  106  of a female type cartridge  101 , and a plurality of grooves  160  are provided in the outer circumference of a liquid inlet  121  of a male type injection port  120 . The grooves  160  may be formed in any one of the L figure groove, inverted L figure groove, J figure groove, and linear spiral groove mentioned above. 
     The cartridge  101  includes a container  102  for defining a storage space  103  containing high concentration methanol as liquid fuel, a valve case  107  inserted in an opening  102   a  formed at one end side of the container  102 , a rubber holder case  111  coupled to one end side of the valve case  107 , and a cartridge base  112  having a nozzle  106  coupled to the rubber holder case  111 . The container  102  may be formed in cylinder, spindle, flat tube, square tube, or any other shape. The cartridge base  112  and the cartridge nozzle  106  are formed integrally. The cartridge nozzle  106  is extended outward from the cartridge base  114 . The integrated product of the base  112 /nozzle  106  and the end portion of the container opening  102   a  are sealed by a rubber packing  105 . 
     The cartridge nozzle  106  includes a nozzle main body  106   b , a valve  108 , a plug  107 , a compression spring  110 , and a seal ring  11 A. In the inner circumference of the nozzle main body  106   b , two protrusions  130  are provided as bayonet coupler elements (key coupling elements). A needle (valve stem)  108   b  of the valve  108  is inserted in the inside passage of the nozzle main body  106   b . The plug  107  surrounds the valve body  108   f  of the valve  108 , and defines a valve compartment space  109 . The compression spring  110  biases the valve body  108   f  toward the valve seat  104   a . The seal ring  11 A is held in a holding groove  108   h  of the valve body  108   f , and is pressed against the valve seat  104   a  by the biasing force of the compression spring  110 . The seal ring  11 A has an irregular section (substantially triangular section). When the seal ring  11 A is forcibly separated from the valve seat  104   a , a liquid inlet  106   c  is opened, and liquid flows toward a liquid outlet  106   a.    
     The rubber holder case  111  is detachably engaged with the inside of the nozzle of the cartridge base  112 . The valve case  107  is detachably engaged with the upper end of the rubber holder case  111  of nearly the same diameter. The material of the valve case  107  and the rubber holder case  111  is a thin resin material (for example, PEEK) having a certain flexibility. On the other hand, the nozzle  106  and the cartridge base  112  are thicker than the cases  107 ,  111  because a certain rigidity is required. 
     As shown in  FIGS. 6A and 6B , a rubber holder  125  as an elastic holder has a bellows section  125   c  provided in the middle of an upper part  125   a  and a lower part  125   b . The bellows section  125   c  is undulated in a ring or spiral form so as to keep a sufficient passage for passing the liquid even after compressive deformation. Accordingly, the methanol solution passes through the bellows section  125   c , and promptly and smoothly flows through without leaking, to be injected in a short time. The rubber holder  125  is formed of nonplastic synthetic rubber defined in hardness in a specified value range. When a liquid receiving part  121  of the cell main body side comes in contact with the rubber holder leading end  125   a , the leading end  125   a  is deformed elastically (compressed), and the nozzle  106  can be displaced. 
     When assembling them, the valve body  108   f  is biased by the spring  110  and incorporated in the case  107 , the flange of the rubber holder  125  is fitted into the recess of the case  111 , the valve case  107  is screwed into the rubber holder case  111 , the flange of the case  111  is fitted into the rubber packing  105  adhered to the cartridge base  112 , the case  111  is screwed into the base  112 , and finally the base  112  is adhered to, and/or crimped and/or engaged with the container opening  102   a.    
     The valve  108  includes a needle  108   b  extended from the front end of the valve body  108   f  (lower side in the drawing), and a guide pin  108   a  extended from the rear end of the valve body  108   f  (upper side in the drawing). The needle  108   b  is elevatably inserted in the passage of the nozzle  106 . The length of the needle  108   b  is nearly equal to the overall length of the passage of the nozzle  106 . However, in a non-use state, that is, when the cartridge  101  is not connected to the cell main body  100 , the length is preferably defined such that the leading end  108   c  of the needle is slightly retracted from the liquid discharge port  106   a  of the nozzle. It is hence effective to avoid damage of the needle leading end  108   c , prevent invasion of foreign matter such as dust from the liquid discharge port  106   a  into the nozzle passage, and prevent accidental opening of the valve. 
     The guide pin  108   a  is extended from the rear end of the valve body  108   f  toward the container  2 , and projects into the liquid storage space  103  through a hole  107   c  in the middle of the top of the case  107 . A plurality of communication holes  107   d  are opened in an upper plate  107   a  of the valve case, and liquid fuel flows into the vale compartment space  109  from the liquid storage space  103  through these communication holes  107   c ,  107   d.    
     A stopper  108   d  is provided in the rear end of the valve body  108   f , and an ascending stroke is defined for allowing the valve body  108   f  to move in the axial direction (Z-direction). That is, when a force larger than the biasing force of the compression spring  110  is applied to the valve body  108   f , the seal ring  11 A is separated from the valve seat  111   a , the liquid inlet is opened, and the valve compartment space  109  communicates with the liquid discharge port  106   a . In this case, the valve body  108   f  does not ascend without limitation, but the ascending motion of the valve body  108   f  is stopped when the stopper  180   d  abuts against the upper plate  107   a  of the valve case. 
     The compression spring  110  is substantially the same as that used in the first embodiment. One end of the compression spring  110  is affixed to the inside of the upper plate  107   a  of the valve case, and the other end thereof is affixed to the small flange of the valve body  108   f.    
     The seal ring  11 A is made of nonplastic synthetic rubber or elastomer free from swelling or dissolving in high concentration methanol solution, and is an O-ring of a substantially triangular irregular section. This seal ring  11 A of irregular section is fitted in the holding groove formed in the lower part of the small flange of the valve body  108   f.    
     Next, the injection port  120  of the fuel cell main body side will be explained below. 
     The injection port  120  includes a liquid receiving part  121  projecting to the center of the liquid inlet  120   a , a valve case  122  formed integrally with the liquid receiving part  121 , a lower member  123  having a plurality of holes  123   a  communicating with the fuel tank (not shown), a valve  126 , a compression spring  127  for thrusting the valve  126 , a seal ring  28 A held in a holding groove of the valve  126 , and a plurality of grooves  160  as bayonet coupler elements. The valve case  122  is screwed into the recess of the fuel cell main body  100 , and is entirely buried in the fuel cell main body. A fuel tank not shown is provided in the fuel cell main body  100 , and a valve compartment space  129  defined by the lower member  123  and the valve case  122  communicates with the fuel tank through the holes  123   a.    
     In the outer circumference of the liquid receiving part  121  of the injection port, two grooves  160  distributed by the 180-degree axial center are formed. These two grooves  160  function as bayonet coupler elements, and formed in position and shape to be fitted respectively with two protrusions  130  of the female type cartridge nozzle  106 . 
     The valve  126  includes a guide pin  126   a , a needle  126   b , a stopper  126   d , a compression spring  127 , a seal ring  28 A, and a valve seat  122   a . While the seal ring  28 A is pressed against the valve seat  122   a , the valve compartment space  129  is cut off from the liquid receiving part  121 . When the pushing force from the nozzle side becomes larger than the biasing force of the compression spring  127 , the seal ring  28 A is separated from the valve seat  122   a , and the valve compartment space  129  communicates with the liquid receiving part  121 . 
     The needle  126   b  is extended from the upper part of the valve  126  toward the liquid receiving part  121 . The principal part of the needle  126   b  is surrounded by the liquid receiving part  121 . A leading end  126   c  of the needle is formed in a recess, and is fitted with the convex needle leading end  108   c  of the cartridge nozzle side valve. When the needles  108   b  and  126   b  are brought closer butt to butt, if the abutting area is small, they are pushed in an offset state, and the passage may not be assured securely. To prevent offset of the needles  108   b  and  126   b , the needle leading end  108   c  of the cartridge nozzle side is formed in a recess, and the needle leading end  126   c  of the injection port side is formed in a convex profile, so that the both can be engaged with each other securely. 
     The guide pin  126   a  is projecting toward the fuel tank (not shown) through the communication holes  123   c  of the lower member  123 . A stopper  126   d  is provided in the rear end of the valve body  126   f , and an ascending stroke is defined for allowing the valve  126  to move in the axial direction. That is, when a force larger than the biasing force of the compression spring  127  is applied to the valve body  126   f , the seal ring  28 A is separated from the valve seat  122   a , and the valve compartment space  129  communicates with the liquid receiving part  121 . In this case, the valve body  126   f  is not lifted without limitation, but the ascending motion of the valve body  126   f  is stopped when the stopper  126   d  abuts against the bottom of the lower member  123 . 
     In the outer circumference of the needles  108   b ,  126   b , and the guide pins  108   a ,  126   a , as shown in  FIG. 15 , a concave groove  38  is formed along the longitudinal axis, and a passage for passing liquid fuel is formed between inner walls of the nozzle  106 . 
     In the case of a coupler for a portable device, the entire structure needs to be formed in a small size, and thus it is hard to assure a passage. Accordingly, aside from the communication holes  107   d ,  123   a , grooves or recesses for passages are formed in these valve elements  108   a ,  108   b ,  126   a ,  216   b  to cover for shortage of passages. 
     Referring to  FIGS. 17 and 18 , the operation will be described below in the case of injecting liquid fuel into the male type injection port of the cell main body from the female type cartridge. 
     The cartridge nozzle  106  is inserted into the liquid inlet  120   a  of the injection port, the protrusion  130  of the nozzle side is insetted with the groove  160  of the injection port side, the nozzle  106  is moved linearly in the axial direction, and then is moved in the circumferential direction. At this position, the leading end of the nozzle  106  is abutting against the rubber holder leading end  125   a  (when the nozzle is inserted by 2.7 mm, the rubber holder comes in contact with the liquid receiving part). 
     Next, when the nozzle  106  is slightly pushed in the axial direction (and also circumferential direction), the rubber holder leading end  125   a  is deformed elastically (compressed), and the needle leading end  108   c  of the cartridge side valve abuts against the needle leading end  126   c  of the injection port side valve (when the rubber holder is compressed by 0.5 mm, the valve needles come in contact with each other). 
     By further pushing the nozzle  106  in the axial direction (and also circumferential direction), the entire rubber holder  125  is compressed, the entire valve body  126   f  is pushed down while resisting the biasing force of the compression spring  127 , and the seal ring  28 A is separated from the valve seat  122   a . When pushed in to the bottom dead center until the stopper  126   d  comes in contact with the bottom plate of the injection port lower member  123 , the cell main body side valve  126  is opened to the full (when the rubber holder is compressed by 1.0 mm, the cell main body side valve is opened fully). 
     By further pushing the nozzle  106  in the axial direction, the entire valve body  108   f  is pushed up while resisting the biasing force of the compression spring  110 , and the seal ring  11 A is separated from the valve seat  111   a . When pushed in to the top dead center until the stopper  108   d  abuts against the upper plate  107   a  of the valve case, as shown in  FIG. 18 , the cartridge side valve  108  is opened to the full (when the rubber holder is compressed by 1.5 mm, the cartridge side valve is opened fully). 
     In this manner, by pushing the cartridge nozzle  106 , the rubber holder  125  is deformed elastically, both the valves  108  and  126  are opened, and liquid fuel flows from the cartridge side to the cell main body side. The opening sequence of the cartridge side valve  108  and the cell main body side valve  126 , that is, the opening and closing order of the valves depends on the relative magnitude of spring coefficients of the compression springs  110 ,  127  biasing the valves. When the spring coefficient of the compression spring  110  of the cartridge side is greater than the spring coefficient of the compression spring  127  of the cell main body side as in this embodiment, the cell main body side valve  126  opens first, and then the cartridge side valve  108  opens later. On the other hand, when the spring coefficient of the compression spring  127  of the cell main body side is greater than the spring coefficient of the compression spring  110  of the cartridge side, the cartridge side valve  108  opens first, and then the cell main body side valve  126  opens later. 
     Referring now to  FIGS. 19A to 26D , various aspects of compatibility between the cartridge and the fuel cell will be explained. 
     Fifth Embodiment 
     In this embodiment, an example of compatibility between two fuel cells and two cartridges will be explained. As shown in  FIGS. 19A and 19B , injection ports  20 C 1 ,  20 C 2  of the cell main body side are of female type, and a small protrusion  30 S and a large protrusion  30 L are provided in the inner circumferences of the female type injection ports  20 C 1 ,  20 C 2 , respectively. As shown in  FIGS. 19C and 19D , cartridge side nozzles  6 C 1 ,  6 C 2  are of male type, and a narrow groove  60 S and a wide groove  60 L are provided in the outer circumferences of the male type cartridge nozzles  6 C 1 ,  6 C 2 , respectively. 
     The cartridge nozzle  6 C 2  in  FIG. 19D  can be connected to either the injection port  20 C 1  in  FIG. 19A  or the injection port  20 C 2  in  FIG. 19B  (compatible). By contrast, the cartridge nozzle  6 C 1  in  FIG. 19C  can be connected to the injection port  20 C 1  in  FIG. 19A , but not to the injection port  20 C 2  in  FIG. 19B  (not compatible). 
     Accordingly, in the fuel cell driven only by low concentration methanol, high concentration methanol will not be injected by mistake. That is, the injection port  20 C 2  in  FIG. 19B  is used in the cell main body driven by low concentration methanol (concentration of about 5% or 30%), and the cartridge nozzle  6 C 1  in  FIG. 19C  is used in the storage container of high concentration methanol (concentration of 100% or 64%). In this case, since the both are not compatible, accidents of the cell main body due to fuel refill error can be prevented. 
     Sixth Embodiment 
     Also in this embodiment, an example of compatibility between two fuel cells and two cartridges will be explained. As shown in  FIGS. 20A and 20B , injection ports  20 D 1 ,  20 D 2  of the cell main body side are of male type, and a narrow groove  160 S and a wide groove  160 L are provided in the outer circumferences of the injection ports  20 D 1 ,  20 D 2 , respectively. As shown in  FIGS. 20C and 20D , cartridge side nozzles  6 D 1 ,  6 D 2  are of female type, and a small protrusion  30 S and a large protrusion  30 L are provided in the inner circumferences of the cartridge nozzles  6 D 1 ,  6 D 2 , respectively. 
     The cartridge nozzle  6 D 1  in  FIG. 20C  can be connected to either the injection port  20 D 1  in  FIG. 20A  or the injection port  20 D 2  in  FIG. 20B  (compatible). By contrast, the cartridge nozzle  6 D 2  in  FIG. 20D  can be connected to the injection port  20 D 2  in  FIG. 20B , but not to the injection port  20 D 1  in  FIG. 20A  (not compatible). 
     Accordingly, in the fuel cell driven only by low concentration methanol, high concentration methanol will not be injected by mistake. That is, the injection port  20 D 2  in  FIG. 20B  is used in the cell main body driven by low concentration methanol (concentration of about 5% or 30%), and the cartridge nozzle  6 D 2  in  FIG. 20D  is used in the storage container of high concentration methanol (concentration of 100% or 64%). In this case, since the both are not compatible, accidents of the cell main body due to fuel refill error can be prevented. 
     Seventh Embodiment 
     In this embodiment, an example of compatibility between three fuel cells and three cartridges will be explained. As shown in  FIGS. 21A ,  21 B, and  21 C, injection ports  20 E 1 ,  20 E 2 ,  20 E 3  of the cell main body side are of female type, and a small protrusion  30 S or a large protrusion  30 L is provided in the inner circumference of the injection ports  20 E 1 ,  20 E 2 ,  20 E 3  selectively at two positions each. As shown in  FIGS. 22A ,  22 B, and  22 C, cartridge side nozzles  6 E 1 ,  6 E 2 ,  6 E 3  are of male type, and a narrow groove  60 S or a wide groove  60 L is provided in the outer circumference of the cartridge nozzles  6 E 1 ,  6 E 2 ,  6 E 3  selectively at two positions each. Two protrusions are distributed symmetrically on the axis in the cell main body injection port by 180 degrees, and two grooves are disposed symmetrically on the axis in the cartridge nozzle by 180 degrees. 
     The cartridge nozzle  6 E 3  in  FIG. 22C  can be connected to any one of the injection ports  20 E 1 ,  20 E 2 ,  20 E 3  in  FIGS. 21A ,  21 B, and  21 C (compatible). By contrast, the cartridge nozzle  6 E 2  in  FIG. 22B  can be connected to the injection port  6 E 1  in  FIG. 22A  and the injection port  6 E 2  in  FIG. 22B  (compatible), but not to the injection port  6 E 3  in  FIG. 22C  (not compatible). The cartridge nozzle  6 E 1  in  FIG. 22A  can be connected only to the injection port  6 E 1  in  FIG. 22A , but not to the injection port  6 E 2  in  FIG. 22B  or the injection port  6 E 3  in  FIG. 22C  (not compatible). 
     Eighth Embodiment 
     In this embodiment, an example of compatibility between four fuel cells and four cartridges will be explained. As shown in  FIGS. 23A ,  23 B,  23 C, and  23 D, injection ports  20 F 1 ,  20 F 2 ,  20 F 3 ,  20 F 4  of the cell main body side are of female type, and a small protrusion  30 S or a large protrusion  30 L is provided in the inner circumference of injection ports  20 F 1 ,  20 F 2 ,  20 F 3 ,  20 F 4  selectively at two positions each. As shown in  FIGS. 24A ,  24 B,  24 C, and  24 D, cartridge side nozzles  6 E 1 ,  6 E 2 ,  6 E 3 ,  6 E 4  are of male type, and a narrow groove  60 S or a wide groove  60 L is provided in the outer circumference of the cartridge nozzles  6 E 1 ,  6 E 2 ,  6 E 3 ,  6 E 4  selectively at two positions each. Two protrusions and two grooves are distributed asymmetrically on the central axis. 
     The cartridge nozzle  6 F 4  in  FIG. 24D  can be connected to any one of the injection ports  20 F 1 ,  20 F 2 ,  20 F 3 ,  20 F 4  in  FIGS. 23A to 23D  (compatible). By contrast, the cartridge nozzle  6 F 3  in  FIG. 24C  can be connected to the injection port  20 F 1  in  FIG. 23A  and the injection port  20 F 3  in  FIG. 23C  (compatible), but not to the injection port  20 F 2  in  FIG. 23B  or the injection port  20 F 4  in  FIG. 23D  (not compatible). The cartridge nozzle  6 F 2  in  FIG. 24B  can be connected to the injection port  20 F 1  in  FIG. 23A  and the injection port  20 F 2  in  FIG. 23B  (compatible), but not to the injection port  20 F 3  in  FIG. 23C  or the injection port  20 F 4  in  FIG. 23D  (not compatible). The cartridge nozzle  6 F 1  in  FIG. 24A  can be connected only to the injection port  20 F 1  in  FIG. 23A , but not to the injection ports  6 F 2 ,  6 F 3 ,  6 F 4  in  FIGS. 23B  to F 23 D (not compatible). 
     Combination of grooves and protrusions in asymmetrical configuration of this embodiment is broader in variation than combination of grooves and protrusions in symmetrical configuration of the seventh embodiment, and it can be applied not only in identification of methanol concentration, but also in identification of methanol and other liquid fuels, or identification of manufacturers. 
     Ninth Embodiment 
     Also in this embodiment, an example of compatibility between four fuel cells and four cartridges will be explained. As shown in  FIGS. 25A ,  25 B,  25 C, and  25 D, injection ports  20 G 1 ,  20 G 2 ,  20 G 3 ,  20 G 4  of the cell main body side are of female type, and a small protrusion  30 S or a large protrusion  30 L is provided in the inner circumference of injection ports  20 G 1 ,  20 G 2 ,  20 G 3 ,  20 G 4  selectively at three positions each. As shown in  FIGS. 26A ,  26 B,  26 C, and  26 D, cartridge side nozzles  6 G 1 ,  6 G 2 ,  6 G 3 ,  6 G 4  are of male type, and a narrow groove  60 S or a wide groove  60 L is provided in the outer circumference of the cartridge nozzles  6 G 1 ,  6 G 2 ,  6 G 3 ,  6 G 4  selectively at three positions each. In this example, three protrusions are distributed symmetrically on the axis in the cell main body injection ports by 120 degrees, and three grooves are distributed symmetrically on the axis in the cartridge nozzles by 120 degrees. 
     The cartridge nozzle  6 G 4  in  FIG. 26D  can be connected to any one of the injection ports  20 G 1 ,  20 G 2 ,  20 G 3 ,  20 G 4  in  FIGS. 25A to 25D  (compatible). By contrast, the cartridge nozzle  6 G 3  in  FIG. 26C  can be connected to the injection ports  20 G 1 ,  20 G 2 ,  20 G 3  in  FIGS. 25A to 25C  (compatible), but not to the injection port  20 G 4  in  FIG. 25D  (not compatible). The cartridge nozzle  6 G 2  in  FIG. 26B  can be connected to the injection port  20 G 1  in  FIG. 25A  and the injection port  20 G 2  in  FIG. 25B  (compatible), but not to the injection port  20 G 3  in  FIG. 25C  or the injection port  20 G 4  in  FIG. 25D  (not compatible). The cartridge nozzle  6 G 1  in  FIG. 26A  can be connected only to the injection port  20 G 1  in  FIG. 25A , but not to any one of the injection ports  20 G 2 ,  20 G 3 ,  20 G 4  in  FIGS. 25B to 25D  (not compatible). 
     According to the invention, if the user does not know the components or concentration of liquid fuel usable in the fuel cell, or if the liquid contained in the cartridge is unknown, the user can actually insert the cartridge nozzle into the injection port of the fuel cell main body, or compare the grooves and protrusions formed in the cartridge nozzle and cell main body injection port, in order to readily judge whether the liquid fuel is usable or not. 
     The foregoing embodiments relate to the liquid injection system for injecting liquid fuel such as methanol from the cartridge into the tank of the fuel cell. However, the invention is not limited to this application alone, and may be also applied to a water injection system for replenishing water from the cartridge into the solid electrolyte film of the fuel cell. Even if the fuel cell is left for a long period of time after stopping power generation operation, the solid electrolyte film in the fuel cell can be humidified by injecting a proper amount of water by using the water injection system. As a result, the fuel cell can be restarted easily. After starting power generation operation, water is produced by dynamic reaction, and power generation operation by high concentration fuel continues. Therefore, the amount of water to be prepared in the cartridge may be smaller than the amount of liquid fuel. 
     The foregoing embodiments relate to the liquid injection system for injecting only liquid fuel. However, the invention is not limited to this application alone, and may be also applied to a liquid injection system capable of injecting both liquid fuel and water. That is, the cartridge is partitioned into two compartments, one compartment is filled with liquid fuel and the other compartment is filled with water, and the liquid fuel and water may be supplied into the fuel cell main body separately from different nozzles provided in the cartridge main body. In this case, however, the injection ports at the fuel cell main body side must be provided separately for liquid fuel and water. 
     The invention is applied to injection of liquid such as high concentration methanol safely into small-sized fuel cell used as a built-in power source of portable telephone, portable audio system, notebook personal computer, portable game machine, and other mobile devices. Its effect is particularly outstanding when using a satellite type cartridge, that is, one cartridge possibly used in plural devices. 
     The liquid fuel of the invention is not limited to methanol fuel, but includes, for example, ethanol fuel such as aqueous ethanol solution and pure ethanol, propanol fuel such as aqueous propanol solution and pure propanol, glycol fuel such as aqueous glycol solution and pure glycol, dimethyl ether, formic acid, and other liquid fuels. Any other liquid fuels suited to the fuel cells may be contained. 
     According to the invention, the liquid fuel can be injected into the fuel cell tank easily by anyone, by connecting the cartridge securely and safely to the injection port of the fuel cell without causing liquid leak. According to the invention, if the user does not know the components or concentration of liquid fuel usable in the fuel cell, or if the liquid contained in the cartridge is unknown, the user can actually insert the cartridge nozzle into the injection port of the fuel cell main body, or compare the grooves and protrusions formed in the cartridge nozzle and cell main body injection port, in order to readily judge whether the liquid fuel is usable or not. 
     Especially in a satellite type cartridge, that is, one cartridge possibly used in plural devices, very effective means is provided from the viewpoint of compatibility and prevention of wrong use.