Liquid fuel storage container for fuel cell and fuel cell system

TECHNICAL FIELD

The present invention relates to a liquid fuel storage container for fuel cell for storing liquid fuel to be supplied to a liquid-fuel direct-supplying type fuel cell and a fuel cell system including the liquid fuel storage container for fuel cell.

BACKGROUND ART

Conventionally, secondary batteries such as nickel-cadmium batteries, nickel-metal hydride batteries and lithium ion batteries have been employed as the power supplies for portable apparatuses such as cellular phones or portable computers. These apparatuses are kept powered ON in many cases and, therefore, there has been a limit to extension of the continuous operating times of the portable apparatus by using the secondary batteries.

To cope therewith, there have been made attempts to utilize fuel cells as the power supplies of the portable apparatuses. Attentions have been focused on direct liquid-fuel supplying type fuel cells which are capable of generating electric power by directly supplying liquid fuel such as methanol and oxygen to the electric-power generating portions of the fuel cells, instead of solid high-polymer fuel cells which use hydrogen as fuel thus involving complicated moisture controls and the like for the electrolyte membranes. Namely, the above direct liquid-fuel supplying type fuel cells do not require the moisture controls and the like for the electrolyte membranes, which have been required for solid high-polymer fuel cells as aforementioned, and have simple configurations.

However, in such direct liquid-fuel supplying type fuel cells, liquid fuel is stored within a container and, the fuel storage container is not settled in attitude since it is employed in a portable apparatus. Accordingly, when the amount of the liquid fuel within the container will be insufficient, the liquid fuel may not exist at the fuel suction port. This causes the difficulty of stably supplying fuel to the electric-power generating portion, thereby becoming unstable operation of the apparatus. Furthermore, since the fuel storage container is not settled in attitude as previously described, there has been studied a configuration that liquid fuel is stored within a container filled with a porous material and a fuel-supplying path made of a capillary tube connects between the inside of the container and the electric-power generating portion. According to the above configuration, it is possible to provide a direct liquid-fuel supplying type fuel cell capable of supplying fuel with high stability, regardless of the attitude of the fuel cell, even when the amount of the liquid fuel will be insufficient.

FIG. 14 illustrates the general outline of the aforementioned configuration. A fuel cell includes a cell stack as an electric-power generating portion 10. The cell stack is configured to include a negative electrode and a positive electrode which are placed with an electrolyte made of a proton-conductive high-polymer electrolyte or hydroxide-ion-conductive high-polymer electrolyte interposed therebetween, wherein liquid fuel is supplied to the negative electrode and oxidizing agent gas is supplied to the positive electrode. The liquid fuel 1 to be supplied to the negative electrode is stored in a stainless-steel container 2 which is filled with a porous material 7 and the inside of the container 2 is connected to the electric-power generating portion 10 through a fuel supplying pipe 8 formed from a capillary tube (refer to Patent document 1, for example).

Patent document 1: JP 2003-77505 A

DISCLOSURE OF THE INVENTION

Subject to be Solved by the Invention

However, with the direct liquid-fuel supplying type fuel cell described in the aforementioned document, since the container 2 is filled with the porous material 7, it can store a small amount of liquid fuel 1. Thus it is difficult to make the apparatus work for a longtime. Further, there is the problem of mixing of impurities such as dusts into the liquid fuel 1 due to the use of the porous material 7, thereby degrading the performance of the electrolyte of the fuel cell. This problem is particularly prominent in a case of using a fiber-type porous material.

The present invention was made in order to overcome the aforementioned problems. It is an object of the present invention to provide a liquid fuel storage container for fuel cell for storing liquid fuel to be supplied to a direct liquid-fuel supplying type fuel cell which is capable of supplying liquid fuel with high stability for a long time and a fuel-cell system including the liquid-fuel storage container.

Means for Solving the Subject

In order to solve the aforementioned problems, the present invention is configured as follows.

Namely, a liquid fuel storage container for fuel cell according to a first aspect of the present invention is characterized by comprising:

a tank member configured to store liquid fuel and be mounted so that mounting attitude of the tank member is not steady, the liquid fuel being directly supplied to a main body of a fuel-cell generating electric power and being able to move freely in a direction of gravity in the tank member; and

a fuel-supplying pipe disposed within the tank member and configured to supply the liquid fuel to the fuel-cell main body and have flexibility, a suction port for sucking the liquid fuel and a weight member, at a portion near the suction port, for keeping the suction port immersed in the liquid fuel.

Further, a fuel-cell system according to a second aspect of the present invention is characterized by comprising the liquid fuel storage container for fuel cell according to the first aspect and a fuel-cell main body which generates electric power by being directly supplied with liquid fuel from the liquid fuel storage container for fuel cell.

In a case of installing, in a portable electronic apparatus, a fuel cell which generates electric power by directly supplying liquid fuel such as an aqueous solution of methanol to an anode electrode thereof, the liquid fuel can freely move toward the direction of gravity within a tank member for storing the liquid fuel. Accordingly, by making a fuel-supplying pipe, extending within the tank member for supplying liquid fuel, of a flexible material and by providing a weight member at a portion near a liquid-fuel suction port of the fuel-supplying pipe, the suction port can move in the direction of gravity any time. With this configuration, the suction port can be kept immersed in the liquid fuel, which enables stably supplying fuel even when the fuel cell is installed in the portable electronic apparatus. Further, it is possible to utilize the major part in the tank member as a liquid-fuel storage region, which enables storing a sufficient amount of liquid fuel for working the apparatus for a long time. Further, a portion of the porous material is small, thus alleviating the problem of mixing of impurities.

Since the fuel-supplying pipe can freely move within the tank member as aforementioned, there is the possibility of entanglement of the fuel-supplying pipe. Therefore, a supporting member can be provided and a length of the fuel-supplying pipe from the supporting member can be restricted to prevent entanglement of the fuel-supplying pipe.

In view of the prevention of entanglement, the fuel-supplying pipe may have a coil-spring configuration or a nest configuration.

The aforementioned weight member may have a spherical shape or the like and may be mounted on the fuel-supplying pipe such that the weight member surrounds the suction port. Further, a porous member may be used for the weight member to enable sucking the liquid fuel, as long as the weight member is immersed in the liquid fuel, even when the suction port is not directly contacted with the liquid fuel. The weight member may be a cylindrical member having substantially the same shape as the cross section of a body portion of the tank member. By employing such a shape, the weight member can slide along an inner surface of the tank member in the axial direction of the tank, noise caused by butting of the weight member against the tank member can be reduced in comparison with a case employing the weight member of the spherical shape or the like. Further, the portion of the cylindrical member corresponding to the suction port may be formed to be a weighting portion having a greater weight than the remaining portion, which enables rotating the cylindrical member in the circumferential direction of the tank member because the weighting portion moves in the direction of gravity. This can reduce the noise caused by butting as aforementioned and also can certainly make the suction port to be disposed in the liquid fuel.

A liquid fuel storage container for fuel cell according to another aspect of the present invention comprises:

a tankmember configured to store liquid fuel and be mounted so that mounting attitude of the tank member is not steady, the liquid fuel being directly supplied to a main body of a fuel-cell generating electric power and being able to move freely in a direction of gravity in the tank member;

a partition member configured to be provided within the tank member, configured to partition an inside region of the tank member into a fuel chamber for storing the liquid fuel and a porous-member chamber containing a porous member for absorbing the liquid fuel, and configured to have a through hole which allow the liquid fuel to pass through the partition member; and

a fuel-supplying pipe configured to supply the liquid fuel to outside of the tank member, configured to be disposed in the porous-member chamber, and configured to have a suction port for sucking the liquid fuel contained in the porous member.

With the aforementioned configuration, since the tank member has the fuel chamber for storing liquid fuel, the liquid fuel storage container can store enough amount of liquid fuel to work an apparatus for a long time. Further, since the portion of the porous member is small, the liquid fuel storage container can alleviate the problem of mixing of impurities.

Effect of the Invention

With the liquid fuel storage container for fuel cell according to the first aspect and the fuel-cell system according to the second aspect of the present invention, since the fuel-supplying pipe extending within the tank member for supplying liquid fuel is made of flexible material, and the weight member is disposed near the liquid-fuel suction port of the fuel-supplying pipe, the suction port can be moved anytime in the direction of gravity, namely toward the liquid fuel. Consequently, the suction port is always kept immersed in the liquid fuel, which enables supplying fuel with high stability even when the fuel cell is installed in the portable electronic apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The aforementioned and other objects and features of the present invention will become more apparent from the following description relating to preferred embodiments with respect to the attached drawings. In the drawings:

FIG. 1 is a cross sectional view of a liquid fuel storage container for fuel cell according to an embodiment of the present invention;

FIG. 2 is a view illustrating an example of modification of the liquid fuel storage container for fuel cell illustrated in FIG. 1;

FIG. 3 is a view illustrating an example of modification of the weight member illustrated in FIG. 1 and FIG. 2;

FIG. 4 is a view illustrating another example of modification of the weight member illustrated in FIG. 1 and FIG. 2;

FIG. 5 is a view illustrating an example of modification of the fuel-supplying pipe illustrated in FIG. 1;

FIG. 6 is a view illustrating another example of modification of the fuel-supplying pipe illustrated in FIG. 1;

FIG. 7 is a view illustrating a further example of modification of the fuel-supplying pipe illustrated in FIG. 1;

FIG. 8A is a view illustrating a liquid fuel storage container for fuel cell including a weight member according to another example of modification of the weight member illustrated in FIG. 1 and FIG. 2;

FIG. 8B is a cross-sectional view taken along the I-I line of FIG. 8A;

FIG. 9A is a view illustrating a liquid fuel storage container for fuel cell including a weight member according to a further example of modification of the weight member illustrated in FIG. 1 and FIG. 2;

FIG. 9B is a cross-sectional view taken along the I-I line of FIG. 9A;

FIG. 10 is a cross-sectional view of a liquid fuel storage container for fuel cell according to another embodiment of the present invention;

FIG. 11 is a view illustrating an example of the structure of the fuel-cell system according to an embodiment of the present invention;

FIG. 12 is a view illustrating another example of the structure of the fuel-cell system illustrated in FIG. 11;

FIG. 13 is a perspective view illustrating a state where the fuel cell system illustrated in Fig. 11 or FIG. 12 is installed in an electronic apparatus; and

FIG. 14 is a cross-sectional view of a conventional fuel storage container.

DESCRIPTION OF NUMERALS

101 to 104: liquid fuel storage container for fuel cell,

110: tank member,

110
a and 110b: opposite end portions,

110
c: inner surface,

110
d: body portion,

112: axial direction,

120: fuel supplying pipe,

121: suction port,

122, 125 and 126: weight member,

127: weighing portion,

140: supporting member,

180: fuel-cell main body, and

185: liquid fuel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

There will be described a liquid fuel storage container for fuel cell and a fuel-cell system according to embodiments of the present invention, with reference to the drawings. The fuel-cell system is a system including the liquid fuel storage container for fuel cell. In the drawings, the same reference characters designate the same components.

First, with reference to FIG. 11, there will be described a fuel cell system 190 including a liquid fuel storage container for fuel cell 101 according to an embodiment.

The fuel-cell system 190 includes a fuel-cell storage container 101, which will be described later in detail, and a fuel-cell main body 180 for generating electric power, wherein the fuel-cell main body 180 is supplied with fuel from the fuel-cell storage container 101. In the present embodiment, the fuel-cell storage container 101 stores an aqueous solution of methanol with a concentration of about 10% as liquid fuel which can be directly supplied to the fuel-cell main body 180. In order to supply the fuel to the fuel-cell main body 180 from the fuel storage container 101, a fuel supplying pump 184 may be provided between the fuel storage container 101 and the fuel-cell main body 180. Also, the fuel storage container 101 may store an aqueous solution of methanol with a higher concentration or an undiluted solution of methanol. In such a case, as illustrated in FIG. 12, it is necessary to provide an intermediate tank 191 connected to the fuel-cell storage container 101 for diluting the high-concentration methanol or methanol undiluted solution supplied from the fuel-cell storage container 101 into an aqueous solution of methanol with a concentration of about 10% and for storing the aqueous solution of methanol.

The fuel cell main body 180 is an electric-power generation module which is constituted by an electrolyte membrane 181, a cathode electrode 182, an anode electrode 183, a catalyst film (not shown) and the like, and generates electric energy by a chemical reaction caused between the liquid fuel supplied to the anode electrode 183 and oxygen in air supplied to the cathode electrode 182. Although there is illustrated, in the figure, only a single cell constituted by the electrolyte membrane 181, the cathode electrode 182 and the anode electrode 183, the fuel cell main body 180 is actually constituted by plural cells which are connected in series to one another.

The fuel cell system 190 having the aforementioned configuration is mounted to a portable electronic apparatus 201 such as a notebook personal computer, as illustrated in FIG. 13. Accordingly, the mounting attitude of the liquid fuel storage container for fuel cell 101 is not settled, which causes the liquid fuel stored in the liquid fuel storage container for fuel cell 101 to freely move in the direction of gravity.

Next, the liquid fuel storage container for fuel cell 101 according to the embodiment will be described.

FIG. 1 illustrates the basic configuration of the liquid fuel storage container for fuel cell 101 according to the embodiment. The liquid fuel storage container for fuel cell 101 includes a tank member 110 and a fuel supplying pipe 120. The tank member 110 has a tank configuration for storing liquid fuel which is to be directly supplied to the anode electrode 183 of the fuel cell main body 180 and is made of a stainless steel in the present embodiment. In the present embodiment, the tank member 110 stores an aqueous solution of methanol with a methanol concentration of about 10% as liquid fuel 185. According to the electric-power generation by the fuel cell main body 180, the amount of liquid fuel 185 within the tank member 110 is decreased. However, the tankmember 110 has an air-intake portion 111 in a side wall thereof and, therefore, even though the liquid fuel 185 is consumed, an amount of air corresponding to the amount of consumed liquid fuel is supplied into the tank member 110 from outside of the tank member 110 through the air-intake portion 111, which prevents reduction of the pressure within the tank member 110 to below the atmospheric pressure, thereby enabling stable supplying of liquid fuel 185. The air-intake portion 111 is made of a selectively-transparent film which passes air therethrouth while preventing liquid from passing therethrough.

Further, in the fuel cell system 190, the tank member 110 preferably has a detachable configuration. Therefore, the liquid fuel storage container for fuel cell 101 includes a detachable connector 130. The connector 130 includes a tank-side connector 131 which is connected to the fuel supplying pipe 120 at the side of the tank member 110 and a main-body side connector 132 provided at the side of the fuel cell main body 180, wherein the tank-side connecter 131 can be detached together with the tank member 110 and the tank-side connector 131 and the main-body side connector 132 can be coupled to each other.

The fuel supplying pipe 120 is a pipe provided within the tank member 110 for supplying the liquid fuel 185 to the fuel cell main body 180. The fuel supplying pipe 120 has flexibility, includes a suction port 121 for sucking the liquid fuel 185 and further includes, near the suction port 121, a weight member 122 for keeping the suction port 121 immersed in the liquid fuel 185. Further, the fuel supplying pipe 120 preferably has a thin pipe shape with an inner diameter which is only enough for generating capillary actions. Also, the fuel supplying pipe 120 may have a greater inner diameter, but should be filled with a fiber-type member with a great number of bubbles. For example, the fuel supplying pipe 120 has an outer diameter of about 1 mm and an inner diameter of about 0.5 mm.

The suction port 121 may be opened at a portion just after the weight member 122 in a liquid suction direction 123 as illustrated in FIG. 1 or may be opened at a portion just before the weight member 122 as illustrated in FIG. 3. In the case where the suction port 121 is opened just before the weight member 122 as illustrated in FIG. 3, the suction port 121 may not be positioned in the liquid fuel 185 depending on the position of the weight member 122 within the tank member 110 and the amount of the liquid fuel 185. Therefore, in the case of the configuration illustrated in FIG. 3, it is preferable to provide a suction member 124 made of a porous material surrounding the weight member 122 and the suction port 121, as illustrated in FIG. 4.

With the liquid fuel storage container for fuel cell 101 having the aforementioned configuration, the suction port 121 can be moved in the direction of gravity, namely towards the liquid fuel 185, anytime, even when the tank 110 is inclined or the amount of the liquid fuel 185 has been reduced. Accordingly, the suction port 121 is kept immersed in the liquid fuel 185, thereby enabling stably supplying the fuel, regardless of the attitude of the tank member 110. Further, it is possible to utilize the major part within the tankmember 110 as the storage region for the liquid fuel 185, which enables storing a sufficient amount of liquid fuel 185 for working the apparatus for a long time. Further, the portion of the porous material is small, thus alleviating the problem of the mixing of impurities.

With the aforementioned configuration illustrated in FIG. 1, there is the possibility of entanglement of the fuel supplying pipe 120 within the tank member 110. Therefore, as illustrated in FIG. 2, a liquid fuel storage container for fuel cell 102 further includes a supporting member 140 provided within the tank member 110 for supporting the fuel supplying pipe 120 and for preventing the entanglement of the fuel supplying pipe 120. The fuel supplying pipe 120 is configured to have such a length that the suction port 121 is positioned at one of the opposite end portions 110a and 110b of the tank member 110 with the fuel supplying pipe 120 supported by the supporting member 140. The other configurations are the same as those of the liquid fuel storage container for fuel cell 102. The supporting member 140 is preferably mounted on an inner surface 110c of the tank member 110 at substantially a middle position of the tank member 110 in an axial direction 112 of the tank member 110. By placing the supporting member 140 at the above-mentioned position, it is possible to restrict the length of the portion of the fuel supplying pipe 120 which is movable within the tank member 110, thereby preventing the entanglement of the fuel supplying pipe 120.

Also, in view of the prevention of entanglement of the fuel supplying pipe 120 within the tank member 110, the fuel supplying pipe 120 may be disposed in a spiral manner as illustrated in FIG. 5 and FIG. 6. Particularly, by curling the fuel supplying pipe 120 in a conical shape as illustrated in FIG. 6, the fuel supplying pipe 120 can be concentrically curled about the weight member 122 in a state that the fuel supplying pipe 120 is folded. Therefore, it is preferable to curl the fuel supplying pipe 120 in a conical shape. Also, it is effective in preventing entanglement of the fuel supplying pipe 120 to arrange a metal wire with a high elasticity along the fuel supplying pipe 120.

Also, as illustrated in FIG. 7, the fuel supplying pipe 120 may have a nest configuration which allows the fuel supplying pipe 120 to expand and contract in an axial direction of the fuel supplying pipe 120, thereby making the fuel supplying pipe 20 foldable.

Also, it is possible to configure a liquid fuel storage container for fuel cell 103 and a liquid fuel storage container for fuel cell 104 employing weight members 125 and 126, respectively, as examples of modification of the weight member 122, as illustrated in FIG. 8A and FIG. 9A.

The weight members 125 and 126 are cylindrical members having substantially the same shape as the cross-sectional area of the body portion 110d of the tank member 110 and also are members slidable within the tank member 110 along the axial direction 112 of the tank member 110.

The weight member 125 is applicable to a tank member 110 having a body portion 110d with a rectangular-shaped cross-sectional area and has a rectangular cylindrical shape, as illustrated in FIG. 8B. A tip end portion 120a of the fuel supplying pipe 120 is mounted on an inner surface 125a of the weight member 125. Further, the tip end portion 120a has the suction port 121.

The weight member 126 is applicable to a tank member 110 having a body portion 110d with a round-shaped cross-sectional area and has a round cylindrical shape, as illustrated in FIG. 9B. A tip end portion 120a of the fuel supplying pipe 120 is mounted on an inner surface 125a of the weight member 125. Further, the weight member 126 is provided with a weighting portion 127 in correspondence with a position at which the tip end portion 120a is mounted. The weighing portion 127 is made of a material or member having a specific gravity greater than that of the weight member 126. The weighting portion 127 may be either formed integrally with the weight member 126 as illustrated in FIG. 9B or formed separately from the weight member 126 and mounted to the weight member 126.

Each of the weight members 125 and 126 can move in the direction of gravity within the tank member 110 along the axial direction 112 of the tank member 110 depending on the attitude of the tank member 110 to dispose the suction port 121 of the fuel supplying pipe 120 at the portion where the liquid fuel 185 exists, similarly to the aforementioned weight member 122. In the case of providing the weight member 122, the weight member 122 may be knocked on the inner surface 110c of the tank member 110 in response to the attitude change of the tank member 110, thereby generating clattery noise due to the knocking, for example. On the contrary, since each of the weight members 125 and 126 slides along the inner surface 110c of the tank member 110 in the axial direction 112, it is possible to suppress the generation of the noise due to the knocking.

Furthermore, in the case of the weight member 126, the weighting portion 127 moves in the direction of gravity and, therefore, the annular weight member 126 can be rotated in a circumferential direction 113 along an inner peripheral surface of the tank member 110. This can suppress the generation of the noise due to the knocking as aforementioned and certainly arrange the suction port 121 at the position of the liquid fuel, thereby enabling generation of electric power even with a smaller amount of residue fuel.

Hereinafter, there will be described a liquid fuel storage container for fuel cell according to another embodiment, with reference to FIG. 10.

A liquid fuel storage container for fuel cell 105 illustrated in FIG. 10 includes a partition member 150 and a fuel supplying pipe 120 within the aforementioned tank member 110 having the aforementioned air-intake portion 111. The partition member 150 is a member partitioning the inside of the tank member 110 into a fuel chamber 114 for storing the liquid fuel 185 and a porous-member chamber 115 for containing a porous member 160 which absorbs the liquid fuel 185 and having one or more through holes 151 which allow the liquid fuel 185 to pass through the partition member 150. The capacity ratio between the fuel chamber 114 and the porous-member chamber 115 is not particularly limited. However, it is preferable that the fuel chamber 114 and the porous-member chamber 115 have nearly the same volume, namely about half of the capacity of the tank member 110, or the capacity of the fuel chamber 114 is slightly greater than that of the porous-member chamber 115 as illustrated in the figure. Further, the fuel supplying pipe 120 is disposed in the porous-member chamber 115 such that the suction port 121 is positioned within the porous member 160. Further, the liquid fuel storage container for fuel cell 105 includes a connector 130 similarly to the liquid fuel storage container for fuel cell 101.

With the liquid fuel storage container for fuel cell 105 having the aforementioned configuration, liquid fuel 185 within the fuel chamber 114 can enter the porous member 160 within the porous-member chamber 115 through the through holes 151 of the partition member 150, regardless of the attitude of the liquid fuel storage container for fuel cell 105. This enables supplying the liquid fuel 185 to the fuel cell main body 180 through the suction port 121 of the fuel supplying pipe 120 positioned in the porous member 60, regardless of the attitude of the liquid fuel storage container for fuel cell 105.

Further, in the liquid fuel storage container for fuel cell 105, the inside of the tankmember 110 is not entirely filled with the porous member 160, which can avoid reduction of the amount of stored liquid fuel 185. This enables utilization of the apparatus for a long time. Furthermore, the porous member 160 has a volume smaller than those of conventional configurations, thereby alleviating the occurrence of the problem of dusts and the like caused by the porous member 160.

Also, it is to be noted that, by properly combining the arbitrary embodiments of the aforementioned various embodiments, the effects possessed by them can be produced.

All of the contents of the specification, drawings and claims of Japanese Patent Application No.2004-147317 filed on May 18, 2004 are incorporated herein by reference.

Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

INDUSTRIAL APPLICABILITY

The present invention is applicable to fuel storage containers for storing liquid fuel to be supplied to a liquid-fuel direct-supply type fuel cell and fuel-cell systems equipped with such fuel storage containers.

Liquid fuel storage container for fuel cell and fuel cell system

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