JP4069359B2 - Liquid fuel cartridge and fuel cell system provided with the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid fuel cartridge and a fuel cell system including the same, and more particularly to a liquid fuel cartridge and a fuel cell system that can be reduced in size and can prevent excessive supply of fuel.
[0002]
[Prior art]
A fuel cell is configured by laminating a fuel electrode (anode electrode), an electrolyte, and an air electrode (cathode electrode). A fuel (hydrogen etc.) is supplied to the fuel electrode and an oxidant (oxygen etc.) is supplied to the air electrode to cause a chemical reaction using a catalyst. And the free energy change by this chemical reaction is taken out directly as electric energy. Since fuel cells theoretically have high power generation efficiency, they are attracting attention as environmentally friendly power sources that contribute to reducing carbon dioxide emissions. In particular, in the direct methanol system, the generation process of hydrogen is integrated, so that the generation of CO ₂ can be minimized.
[0003]
Various forms are considered as a form of storing fuel in a container and supplying it to the fuel electrode. For example, in a direct methanol fuel cell (DMFC) expected as a power source for portable equipment, methanol as a fuel, The liquid is supplied to the fuel electrode. Such liquid fuel needs to be supplied in an appropriate amount according to the amount of fuel consumed at the fuel electrode. If the supplied fuel is too small, an electromotive force shortage occurs, and if the supplied fuel is too large, a crossover phenomenon occurs in which the fuel flows into the electrolyte without causing a reaction at the fuel electrode.
[0004]
Japanese Patent Laid-Open No. 2001-93551 discloses a fuel including a pressure adjusting mechanism that keeps the pressure in a container constant in order to stably supply liquid fuel, and a liquid absorbing material that guides the liquid fuel to the outlet by capillary action. A containment vessel is disclosed.
[0005]
[Problems to be solved by the invention]
However, it has been difficult for the conventional fuel container to supply an appropriate amount of fuel according to the fuel consumption. In particular, the crossover phenomenon due to the excessive supply of fuel could not be sufficiently prevented.
[0006]
An object of the present invention is to provide a fuel cartridge capable of supplying an appropriate amount of liquid fuel according to the amount of fuel consumption and effectively preventing a crossover phenomenon.
[0007]
Furthermore, it aims at providing the reliable fuel cell system provided with the said fuel cartridge.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, a fuel cartridge according to the present invention includes a casing in which an air inlet and a fuel outlet are formed, and a porous body impregnated with liquid fuel and accommodated in the casing. The volume in the non-compressed state of the porous body is 1.1 to 2.5 times the volume of the space in the casing, and the space in the casing is filled .
[0009]
In the fuel cartridge of the present invention , a porous body that is compressed and compressed and impregnated with a liquid fuel is accommodated in a housing in which an air inlet and a fuel outlet are formed. Since the porous body is compressed, the negative pressure can be adjusted. In particular, the volume of the porous body in an uncompressed state is desirably 1.1 to 2.5 times the volume in the housing.
[0010]
The porous body is preferably in the form of a sponge having a large number of pores or voids, and the porosity of the porous body is preferably 99% to 30%.
[0011]
The present invention also relates to a fuel cartridge for a fuel cell in which liquid fuel is accommodated in a housing in which an air intake port and a fuel intake port are formed, wherein the air intake port is a folded tubular air. Has a passage. As a result, the flow path length can be increased, and fuel evaporation can be minimized.
[0012]
The present invention also relates to a fuel cartridge for a fuel cell in which liquid fuel is accommodated in a housing in which an air intake port and a fuel outlet port are formed, and the air intake port is formed on an outer surface of the housing. It is formed in a non-linear shape along. As a result, the length of the flow path can be increased, and the handleability can be improved by making it compact.
[0013]
The present invention also relates to a fuel cartridge for a fuel cell in which liquid fuel is accommodated in a casing in which an air intake port and a fuel intake port are formed, and the air intake port has a radius within the flow path. It has a channel length of 10r to 2000r with respect to r. Thus, by elongating the flow path length with respect to the opening area, it is possible to minimize the evaporation of fuel while communicating with the outside air.
[0014]
The present invention also relates to a fuel cartridge for a fuel cell in which liquid fuel is accommodated in a casing in which an air inlet and a fuel outlet are formed, wherein the air inlet is on the outer surface side of the casing. A groove formed along the groove, one end of which communicates with the inside of the housing, and the groove forming surface of the housing can be covered from the outer surface side, and the other end of the groove can be opened to the outside of the housing. Sheet. As a result, the length of the flow path can be increased, and manufacturing or recycling can be facilitated.
[0015]
In the fuel cartridge, the sheet is preferably thermocompression bonded to the groove forming surface of the housing.
[0016]
In the fuel cartridge, the liquid fuel preferably contains methanol, an aqueous methanol solution, chemical hydride, gasoline , NaBH ₄ , or dimethyl ether.
[0017]
The fuel cell system of the present invention includes the above fuel cartridge, and a fuel cell that uses the liquid fuel taken out from the fuel outlet of the fuel cartridge and outputs electric energy by an electrochemical reaction. Since the fuel cartridge is provided, it is possible to provide a highly reliable fuel cell system that is unlikely to be excessively supplied.
[0018]
In the fuel cell system, the fuel cell includes a protrusion having a fuel inlet for introducing the liquid fuel from the fuel cartridge at the tip, and the fuel outlet of the fuel cartridge has the protrusion A sealing portion that seals the base end side of the protrusion from the fuel inlet when inserted, and an opening operation portion that opens to supply the liquid fuel to the fuel inlet when the protrusion is inserted; It is desirable to provide. This facilitates attachment and replacement of the fuel cartridge to the fuel cell.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0020]
(Overall system configuration)
FIG. 1 shows a schematic configuration of a fuel cell system according to an embodiment of the present invention. As shown in the figure, the fuel cell system includes a fuel cartridge 20, a fuel cell 10 that receives fuel from the fuel cartridge, and an auxiliary device 30 that discharges exhaust from the fuel cell. In this example, for the sake of compactness, the elements are arranged in order, but the elements may be arranged in other ways.
[0021]
FIG. 2 shows the connection relationship of each element of the fuel cell system. The fuel cartridge 20 is housed in the holder 65 of the fuel cell 10. The holder 65 communicates with the fuel diffusion layer of the fuel cell 10 through the fuel introduction tube 28 so that the liquid fuel of the fuel cartridge 20 can be supplied. The discharge port 38 of the fuel cell 10 communicates with the auxiliary device 30, and the discharge from the fuel cell 10 is discharged to the tube 36 by driving the auxiliary device 30. Electric energy is output from the fuel cell 10 through lead wires 12a and 13a.
[0022]
(Fuel cell)
As the fuel cell 10, DMFC is adopted in this embodiment. However, as long as the fuel is stored in a liquid, another type of fuel cell may be used. As shown in FIG. 1, a fuel cell 10 includes a polymer membrane / electrode assembly (hereinafter referred to as a polymer membrane 1), a fuel electrode 2 and an air electrode 3 joined to the respective surfaces of the polymer membrane. 6) (referred to as “joined body”). As the polymer film, a solid polymer film or the like is generally used, and a catalyst layer such as Pt, Ru, Pt-Ru or the like is formed in close contact with the polymer film. Further, a fuel diffusion layer 5 is formed on the fuel electrode 2 side of the joined body, and an air diffusion layer 4 is formed on the air electrode 3 side. Each of the fuel diffusion layer 5 and the air diffusion layer 4 is composed of a porous membrane made of a mesh metal foam. The facets of the joined body 6, the fuel diffusion layer 5, and the air diffusion layer 4 are airtightly covered with a gasket or the like (not shown). Each of the fuel diffusion layer 5 and the air diffusion layer 4 is provided with a current collecting member (not shown) so that the generated electric energy can be taken out. The fuel cell 10 further includes a fuel inlet (described later) for taking out fuel from a fuel outlet (described later) of the fuel cartridge 20, and this fuel inlet communicates with the fuel diffusion layer 5.
[0023]
3 is a plan view (a) and a bottom view (b) showing a detailed configuration example of the fuel cell 10, and FIG. 4 is a cross-sectional view taken along lines AB and BC in FIG. 3 (a). It is a combination of and expanded. In the fuel cell 10, a joined body 6, an air diffusion layer 4, a fuel diffusion layer 5, and current collecting members 12 and 13 are accommodated between base plates 17 and 18. The peripheries of the base plates 17 and 18 are sealed with a gasket or an indeterminate sealing material, and are sealed with screws, adhesion, welding, or other fixing methods.
[0024]
The fuel diffusion layer 5 includes a current collecting member 12 and is adjacent to the fuel chamber 15. The fuel chamber 15 communicates with a fuel introduction port described later via a fuel introduction tube 28. The current collecting member 12 is electrically connected to the lead wire 12a. On the other hand, the air diffusion layer 4 includes a current collecting member 13 and is adjacent to a base plate 18 including a large number of air inlets 14. The air diffusion layer 4 communicates with the discharge port 38. The current collecting member 13 is electrically connected to the lead wire 13a.
[0025]
(Operation of fuel cell)
Next, the operation of the fuel cell 10 of the present embodiment will be described.
[0026]
When a liquid fuel, for example, a methanol solution (such as a 3% methanol solution) is supplied from the fuel cartridge 20, the methanol solution is introduced into the fuel introduction tube 28 and the fuel chamber 15, and diffuses in the fuel diffusion layer 5 to form the fuel electrode 2. Led to. In the fuel electrode 2, carbon dioxide, protons and electrons are generated from the methanol solution. Carbon dioxide is discharged through the fuel diffusion layer 5, and protons diffuse into the polymer membrane 1. On the other hand, air (oxygen) diffuses in the air diffusion layer 4 and is guided to the air electrode 3. At the air electrode, oxygen reacts with protons to produce water and consumes electrons.
[0027]
The electrical output from the fuel cell 10 obtained in this way is taken out through the current collecting members 12 and 13 and output to the outside through the lead wires 12a and 13a.
[0028]
(Details of fuel cartridge)
FIG. 5 is a view showing a cross-sectional structure of the fuel cartridge of the present embodiment. As shown in the figure, the fuel cartridge 20 includes a casing 21 that stores liquid fuel. A porous body (foam) 23 impregnated with liquid fuel is accommodated in the housing 21. The shape of the porous body may be a so-called sponge or fiber, but it is necessary to have a large number of pores or voids. The porosity of the porous body (foam) is 99 to 30%, and preferably has a porosity of about 90 to 50% in order to retain the liquid. When the depth (height) in the casing is 1, the vertical length (height) of the foam in an uncompressed state is 1.0 to 1.5, and the horizontal length in the casing is Is 1, the horizontal length of the foam in an uncompressed state is 1.0 to 2.0, preferably 1.2 to 1.7. It is desirable to apply a negative pressure to the liquid fuel in advance by filling the porous body 23 so as to fill the space in the casing 21. Furthermore, it is desirable to adjust the negative pressure by compressing and storing the porous body 23 in the housing 21. When the volume in the housing 21 is 1, the volume of the foam in an uncompressed state is desirably 1.1 to 2.5, and more preferably 1.2 to 1.8. The material of the porous body 23 can be any material such as polyurethane and polyester, but the liquid fuel used in the present invention is modified with chemical aqueous hydride, gasoline , NaBH ₄ , dimethyl ether, etc. in addition to methanol aqueous solution. Therefore, a material having excellent organic solvent resistance is preferable so that a liquid fuel for taking out hydrogen can be retained. By applying a negative pressure as described above, it is possible to prevent excessive supply of fuel.
[0029]
When the fuel in the casing 21 is consumed, the required negative pressure is maintained by taking in air from the air intake port 22 (see FIG. 1) provided in the casing 21. The air intake 22 is preferably in communication with the atmosphere while minimizing fuel evaporation. In order to minimize the evaporation of fuel, the air intake 22 is formed so that the flow path length is considerably longer than the opening cross-sectional area. In order to increase the flow path length, the air intake port 22 has a bent tubular shape. The flow path length is preferably 10r to 2000r, more preferably 50r to 1500r, and still more preferably 100r to 1000r with respect to a radius r of a through hole 75 (described later) of the air intake port 22. By increasing the flow path length of the air intake port 22 in this way, even if vaporized fuel reaches the flow path, the outflow from the housing 21 to the outside can be minimized. Further, it is considered that the flow path resistance is increased by increasing the flow path length of the air intake port 22. However, when the fuel is consumed, an appropriate amount of air is introduced relatively smoothly.
[0030]
When forming the air intake port 22 having a long flow path length, as shown in FIG. 1, it is easier to manufacture along the outer surface of the housing 21 and the handling is convenient. In forming the air inlet 22, it is desirable to form a groove 77 along the outer surface side of the housing and cover the groove with the films 8 and 8a. Thereby, manufacture is easy and at the time of recycling of a housing | casing, even if the flow path of the air intake 22 is clogged, a film can be peeled and it can wash | clean easily. One end of the groove 77 communicates with the inside of the housing through a through hole 75 provided in the housing. The other end of the groove 77 can form an atmosphere opening 79 that can communicate with the atmosphere by peeling off a part (8a) of the film during use.
[0031]
(Details of fuel outlet)
The configuration of the fuel outlet of the fuel cartridge 20 and the fuel inlet of the fuel cell will be described with reference to FIG. As described above, the casing 21 contains the porous body 23 impregnated with the liquid fuel, and applies a required negative pressure to the liquid fuel. A filter 39 is interposed in the housing 21 so as to contact the porous body and cover the fuel outlet 24. The fuel outlet 24 is sealed by sticking a sealing material 7 to the outer end thereof, and a closed space 60 is formed between the valve body 49 and the sealing material 7.
[0032]
On the other hand, a fuel intake member 42, which is a protrusion, is implanted in the casing 41 of the fuel cell 10. When the fuel cartridge 20 is mounted at a predetermined position of the fuel cell casing 41, the fuel intake member 42 penetrates the sealing material 7 and is liquid-tightly coupled to the packing 45 so as to be within the fuel cartridge casing 21. And the fuel diffusion layer 5 of the fuel cell are communicated with each other.
[0033]
The fuel intake member 42 is a cylindrical body that communicates with the fuel diffusion layer 5 of the fuel cell. The fuel intake member 42 has a tapered portion at the tip, and a fuel inflow through hole, that is, fuel intake holes 44, 44. Is drilled. The tip of the fuel intake member 42 is formed in an appropriate sharp shape so that when the sealing material 7 at the fuel outlet is pressed, the sealing material 7 is tensioned and the sealing material can be broken.
[0034]
As shown in FIG. 5B, the packing 45 has a tapered portion 43 formed on the inner peripheral surface thereof, and a cylindrical fitting portion 47 formed on the inside of the housing at the tip. Further, the valve body 49 as an opening operation portion is constantly pressed on the upper surface of the packing 45 by the force of the spring 48 to close the flow path. When the fuel intake member 42 is inserted to a specified position, the valve body 49 is pushed up by the fuel intake member 42 and the flow path is opened.
[0035]
In such a fuel cartridge, a stainless steel filter 39 is fixed to the main body of the polymer casing 21 by heat welding, and a spring 48, a valve body 49, and a packing 45 are sequentially inserted from the fuel outlet 24. Then, the fuel outlet 24 is sealed by heat sealing with the sealing material 7. The sealing material 7 not only prevents fuel leakage but also acts as a member that prevents the packing 45 from being pushed out by the spring 48.
[0036]
Next, the porous body 23 is pushed into the main body of the casing 21, and the lid of the casing 21 is thermally welded to the main body. Next, the inside of the housing is decompressed and liquid fuel is injected. After that, the casing is opened to the atmosphere, but the air intake port 22 of the casing 21 is sealed with the films 8 and 8a by thermocompression with the pressure reduced again. The fuel cartridge sealed with the films 8 and 8a is accommodated in an outer bag made of a film having an air shielding property and packed in a decompressed state.
[0037]
Next, a method for loading the fuel cartridge 20 into the fuel cell 10 will be described. 6 and 7 show the loading process of the fuel cartridge. The outer bag which is packed is opened, the fuel cartridge 20 is taken out, and the film 8a sealing the air intake port 22 of the housing 21 is peeled off. Thereafter, the lever 58 of the cartridge holder 65 formed in the casing 41 of the fuel cell is opened, and the fuel cartridge 20 is loaded. The protruding portion 25 of the fuel cartridge 20 is received by the protrusion 14 of the lever 58, and the other end side is supported by the inclined surface portion 13 b of the holder 65.
[0038]
When the lever 58 is closed in this state, the protrusion 14 rotates downward as shown in FIG. 7, and the fuel outlet 24 of the fuel cartridge 20 contacts the tip of the fuel inlet member 42.
[0039]
When the lever 58 is further rotated, the fuel outlet 24 is pushed into the fuel intake member 42. When the lever 58 is pushed to the end, the lever 58 is engaged with the flange portion 16 and the fuel cartridge 20 is fixed to the holder 65.
[0040]
When taking out the fuel cartridge 20 from the holder 65, the lever 58 is rotated upward after the engagement between the flange portion 16 and the lever 58 is released. As a result, the fuel cartridge 20 is pulled up to the lever 58, and the fuel outlet 24 comes out of the fuel inlet member 42. When the lever 58 is further rotated, the upper half of the fuel cartridge 24 is exposed from the holder 65, so that the fuel cartridge 24 can be easily removed from the holder 65.
[0041]
When the fuel cartridge 20 is pushed into the fuel outlet 24 in the mounting process of the fuel cartridge 21, the seal member 7 receives tension from the tip of the fuel inlet member 42, and stress concentrates on the abutting portion and tears. Is released to the atmosphere.
[0042]
When the fuel cartridge 20 is further pushed in, the fuel intake member 42 is guided by the tapered portion 43 and inserted into the packing 45. As a result, the fitting portion 47 of the packing 45 is liquid-tightly fitted to the fuel intake member 42 as shown in the drawing. Then, the fuel intake member 42 pushes the valve body 49 open to allow the casing 21 to communicate with the casing 41 of the fuel cell, so that fuel can be supplied to the fuel cell 10.
[0043]
The valve body 49 is provided for the convenience of replacing the fuel cartridge 20 on the way, but the valve body 49 and the spring 48 may be omitted. In this case, a film that closes the opening may be provided behind the fitting portion 47 as the opening operation portion, and the fuel intake member 42 that has passed through the fitting portion 3 may break the film.
[0044]
Further, although the fitting portion 47 has been described as forming part of the packing 45, other configurations may be used as long as the coupling with the fuel intake member 42 is liquid-tight. For example, the fuel intake member 42 may be inserted into a ring-shaped rubber ring.
[0045]
(Auxiliary equipment)
FIG. 8 is a partially cutaway plan view showing an example of the auxiliary device 30. Here, the auxiliary device 30 is configured as a tube pump, and actively sucks, from the fuel cell 10, discharge such as water generated on the air electrode 3 side of the fuel cell and diffusing into the air diffusion layer 4. The auxiliary device 30 includes a main body 32 having a space portion formed therein and an inner surface of the space portion formed in an arc surface in a cross section in a specific direction, and a tube 36 formed of an elastic material and laid along the arc surface. And. Further, in the space portion of the main body 32, a rotation support 33 that can rotate around an axis in a direction perpendicular to the specific direction, and an edge of the rotation support 33, and a rotation support 33 And a plurality of rollers 34a, 34b, 34c that are rotatable about an axis parallel to the axis.
[0046]
In such a configuration, when the rotary support 33 is rotationally driven by a driving means (not shown), at least one of the plurality of rollers 34a, 34b, 34c is between the outer peripheral surface and the arc surface. Then, the tube 36 is moved while being crushed. Thereby, the liquid in the tube 36 can be sent to the arrow X direction. By connecting the suction side of the tube 36 to the discharge port 38 (see FIG. 3) from the air diffusion layer 4 of the fuel cell, it is possible to positively suck the discharge.
[0047]
Depending on the nature of the fuel cell used, the exhaust may be further chemically treated, a specific component may be extracted or removed, or fed back to the fuel electrode 2 side. When carbon dioxide is discharged from the fuel electrode, a gas-liquid separation chamber or the like communicating with the fuel diffusion layer 5 may be provided to separate and discharge the carbon dioxide, which may be sucked by the auxiliary device 30. It is good also as a structure which does not provide the auxiliary device 30 and does not attract | suck discharge | emission positively.
Further, if the fuel cartridge of the embodiment is used, the volatilization of the fuel can be suppressed to a low level, so that an energy-friendly fuel cell system can be obtained with little energy loss.
[0048]
【The invention's effect】
According to the present invention, it is possible to provide a fuel cartridge that can supply an appropriate amount of liquid fuel according to the amount of fuel consumption and can effectively prevent the crossover phenomenon. In addition, a highly reliable fuel cell system including the fuel cartridge can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a fuel cell system according to an embodiment of the present invention.
FIG. 2 is a diagram showing a connection relationship of each element of the fuel cell system.
FIG. 3 is a plan view (a) and a bottom view (b) showing a detailed configuration of a fuel cell.
4 is a cross-sectional view taken along the line A-B-C in FIG.
FIG. 5 is a diagram showing a cross-sectional structure of a fuel cartridge according to the present embodiment.
FIG. 6 is a diagram showing a loading process of a fuel cartridge.
FIG. 7 is a diagram illustrating a loading process of a fuel cartridge.
FIG. 8 is a partially cutaway plan view showing an example of an auxiliary device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 22 ... Air intake port, 24 ... Fuel extraction port, 21 ... Housing of fuel cartridge, 23 ... Porous body impregnated with liquid fuel, 77 ... Groove, 8, 8a ... Sheet, 10 ... Fuel cell, 42 ... Fuel removal Insertion member (protrusion part), 44 ... Fuel intake hole (fuel introduction port), 47 ... Fitting part (sealing part), 49 ... Valve body (opening operation part)

Claims (6)

A housing in which an air inlet and a fuel outlet are formed;
A porous body impregnated with liquid fuel and accommodated in the housing,
The porous body is a fuel cartridge for a fuel cell , wherein a volume in an uncompressed state is 1.1 to 2.5 times a volume of a space in the casing, and the space in the casing is filled . In claim 1 ,
The fuel cartridge for a fuel cell, wherein the porous body is a sponge having a large number of pores or voids. In claim 1 or 2 ,
A fuel cartridge for a fuel cell, wherein the porosity of the porous body is 99% to 30%. In any one of Claims 1 thru | or 3,
The fuel cartridge for a fuel cell, wherein the liquid fuel includes methanol, aqueous methanol solution, chemical hydride, gasoline , NaBH ₄ , or dimethyl ether. A fuel cartridge according to any one of claims 1 to 4 , and
A fuel cell that uses the liquid fuel taken out from the fuel outlet of the fuel cartridge and outputs electric energy by an electrochemical reaction;
A fuel cell system comprising: In claim 5 ,
The fuel cell includes a protrusion having a fuel inlet for introducing the liquid fuel from the fuel cartridge opened at the tip,
The fuel outlet of the fuel cartridge includes a sealing portion that seals the base end side of the protrusion from the fuel inlet when the protrusion is inserted, and a fuel inlet when the protrusion is inserted. A fuel cell system comprising: an opening operation unit that opens to supply the liquid fuel.

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