JP4806922B2 - Fuel cell and fuel cell control method - Google Patents

Description

  The present invention relates to a fuel cell and a fuel cell control method.

  With the arrival of the information society in recent years, the amount of information handled by electronic devices such as personal computers has increased dramatically, and the power consumption of electronic devices has also increased remarkably. In particular, in portable electronic devices, an increase in power consumption is a problem with an increase in processing capability. Currently, in such portable electronic devices, lithium ion secondary batteries are generally used as power sources, but the energy density of lithium ion secondary batteries is approaching the theoretical limit. Therefore, in order to extend the continuous use period of the portable electronic device, there is a limitation that the power consumption must be reduced by suppressing the CPU driving frequency.

  In such a situation, instead of a lithium ion secondary battery, a fuel cell having a large energy density and high energy efficiency is used as a power source of the electronic device, so that the continuous use period of the portable electronic device is greatly increased. It is expected to improve.

  The fuel cell includes a fuel electrode and an oxidant electrode, and an electrolyte membrane provided between them. The fuel electrode is supplied with fuel, and the oxidant electrode is supplied with an oxidant to generate electric power through an electrochemical reaction. In general, hydrogen is used as the fuel, but in recent years, methanol is reformed to produce hydrogen by reforming methanol using methanol, which is cheap and easy to handle, and methanol is directly used as fuel. Direct fuel cells are also being actively developed.

By the way, in a fuel cell using air as an oxidant, the oxidant electrode side is open to the atmosphere. During operation, it is necessary that the oxidizer electrode is in good contact with the air. However, if the stopped state is several days or longer, the water contained in the solid polymer electrolyte membrane is volatilized. There was a problem of drying out. Once the solid polymer electrolyte membrane is dried, even if it tries to absorb water, it does not readily absorb water in a short time, and the characteristics cannot be maintained. In order to solve this problem, Patent Document 1 discloses that an air supply line that supplies air to an air electrode of a fuel cell and an air discharge line that discharges air from the air electrode close air circulation when the fuel cell is stopped. A fuel cell comprising means is disclosed.
JP 2002-216823 A

  The technique disclosed in Patent Document 1 is effective not only in a fuel cell using a gas such as hydrogen disclosed in the document but also in a direct fuel cell for the purpose of suppressing drying of the electrolyte.

  However, when the present inventor examined a fuel cell in which liquid fuel such as methanol is directly supplied to the fuel electrode as a fuel, as in the configuration of Patent Document 1 described above, a closing member is provided in a part of the supply path of the oxidant. Even when the fuel cell is provided, it has been found that the fuel passes through the electrolyte membrane and evaporates from the oxidant electrode side while the fuel cell is stopped. Further, it has been found that the concentration of fuel components such as methanol in the liquid fuel contained in the fuel container gradually decreases. This is considered to be mainly due to poor airtightness in the fuel cell. Even if the oxidant supply line and the discharge line are shut off by the shutoff valve, the pressure of the liquid fuel gasified and remaining inside the oxidizer electrode changes due to the temperature change in the battery before and after the shutoff, and the shutoff valve sealing part It is inevitable that a volume change occurs in the sealing member used in the above. As a result, methanol evaporated from the resulting gap, leading to a decrease in methanol concentration as described above, leading to wasted liquid fuel.

In addition, the gas from the remaining liquid fuel may react with oxygen that has permeated through the electrolyte membrane to produce formic acid or formaldehyde, which may deteriorate the current collecting member.
In addition, the gas from the liquid fuel contracts due to the temperature drop after the fuel cell is stopped, the inside of the oxidant electrode becomes negative pressure, and the joint part of the solid electrolyte membrane-catalyst electrode composite is peeled off. Deterioration has also occurred.

  The present invention has been made in view of the above circumstances, and an object thereof is a fuel cell in which liquid fuel supplied to the fuel electrode of a direct type fuel cell is less wasted when the fuel is stopped and the deterioration of components due to residual gas is small. There is in getting.

  According to the present invention, in the fuel cell, the unit cell includes at least a solid electrolyte membrane, a fuel electrode disposed on one surface of the solid electrolyte membrane, and an oxidant electrode disposed on the other surface. The first unit cell and the second unit cell are arranged so that the oxidant electrodes face each other, and the interval between the first unit cell and the second unit cell is adjusted. Thus, a fuel cell comprising the interval adjusting means can be obtained.

  In the fuel cell of the present invention, the interval between the unit cells can be adjusted to cover and expose the oxidant electrode without any gap. When the fuel cell is stopped, the oxidant electrode is covered with the opposite oxidant electrode without any gaps, so that there is almost no space in the oxidant electrode. There is almost no deterioration of parts.

  In the present invention, the first unit cell and the second unit cell may be supported by a first housing and a second housing, respectively, from which the oxidizer electrode is exposed. . With this configuration, the housing can be used as a means for covering the oxidant electrode without any gap.

In this invention, it is good also as a structure which has the cross-sectional shape which mutually complements an unevenness | corrugation on the surface of each said oxidizing agent electrode.
In the present invention, a sealing member may be provided on at least one surface of the opposing oxidant electrode.
If such a concavo-convex structure or a sealing member is used, when the oxidant electrodes facing each other are in closest contact, the cross-sectional shape meshes with no gaps, leaving no wasted space. Therefore, the influence of gasification of the residual liquid fuel hardly occurs.

  In the present invention, a shielding member can be provided between the opposing oxidant electrodes. By using the shielding member in this manner, the surface of the oxidant electrode can be covered with the shielding member without any gap regardless of the cross-sectional shape of the opposing oxidant electrode.

  In this configuration, the shielding member having a concavo-convex shape on at least one of the oxidant electrode surface in the first unit cell or the oxidant electrode surface in the second unit cell and having a cross-sectional shape that complements the concavo-convex shape. It can also be provided. As a result, the surface of the oxidant electrode can be more reliably covered with the shielding member without a gap.

  In the present invention, the unit cell is a fuel cell comprising at least a solid electrolyte membrane, a fuel electrode disposed on one surface of the solid electrolyte membrane, and an oxidant electrode disposed on the other surface. The oxidizer electrode of the first unit cell and the fuel electrode of the second unit cell are arranged to face each other, and the interval between the first unit cell and the second unit cell is adjusted. Therefore, the present invention provides a fuel cell comprising a gap adjusting means.

  In the fuel cell of the present invention, the interval between the unit cells can be adjusted to cover and expose the oxidant electrode without any gap. When the fuel cell is stopped, the oxidant electrode is covered with the opposite fuel electrode without any gaps, so that there is almost no space in the oxidant electrode. There is almost no deterioration.

  Also in this configuration, the fuel cell can be supported by the housing in an arrangement in which the oxidant electrode is exposed, and this configuration shields the surface of the oxidant electrode without being affected by the shape of the opposing fuel electrode. It becomes possible to cover without gaps by the member. Further, it is possible to form an unevenness that completely complements the unevenness of the surface of the oxidant electrode facing the surface of the housing, or to provide a sealing member on at least one of the surface of the oxidant electrode facing the surface or the surface of the shielding member. As a result, the surface of the oxidizing agent is more completely covered.

  In the present invention, the distance adjusting means is connected to the support bar penetrating at least one of the first casing and the second casing, and is connected to the support bar. Drive means for moving at least one of the two housings along the support bar can be employed.

  In the present invention, the support bar may have a screw structure on the surface, and the driving means may apply a rotational force to the support bar. The driving means may be composed of a motor and connecting means for connecting the motor and the support rod.

  If such a drive means is used, the space | interval of fuel cells can be adjusted by the screwing which uses the motor as a drive source to the housing | casing of a support rod.

  In this invention, the said space | interval adjustment means can be an actuator provided in at least one among said 1st housing | casing and said 2nd housing | casing.

  In the present invention, the actuator is an electromagnetic drive actuator, and includes at least a magnet, a coil that is movable by the magnet, and a holding portion of the coil, and the first casing and the second casing. The magnet may be fixed to one of the bodies, and the tip of the coil may be fixed to the other.

  If such an actuator is used, the distance between the fuel cells can be adjusted by the expansion and contraction of the actuator itself without the support rod with a thread groove and the screw hole of the housing.

  The present invention is not necessarily applied only to unit cells, but can also be applied to a fuel cell having a planar stack structure in which a plurality of the first unit cells and the second unit cells are provided in a plane.

  In the present invention, a configuration having an operation state detection unit that detects an operation state of the fuel cell, and a control unit that controls the operation of the interval adjusting unit based on the operation state detected by the operation state detection unit. It can be. By so doing, it is possible to more reliably control covering and exposing the oxidizer electrode without gaps according to the operating state of the fuel cell.

  In the present invention, when the operation of the fuel cell is stopped, the first unit cell and the second unit cell are brought closer to each other by the interval adjusting unit, and when the operation of the fuel cell is started, the first unit cell is made by the interval adjusting unit. The cell and the second unit cell can be moved away. In this way, during operation of the fuel cell, the oxidant is more reliably supplied to the oxidant electrode, and the transpiration of the liquid fuel and the component deterioration due to the residual liquid fuel after the stop of the fuel cell are further reliably suppressed. be able to.

  It should be noted that any combination of these components, or a conversion of the expression of the present invention between methods, apparatuses, etc. is also effective as an aspect of the present invention.

  In the fuel cell of the present invention, the shape of the planar stack is not limited to one. Not only the form having one solid electrolyte for each single cell but also the form in which a single solid electrolyte is shared by a plurality of cells does not depart from the spirit of the present invention.

  As described above, according to the present invention, it is possible to control the supply of the oxidant and the presence or absence of the space in the cell by adjusting the distance between the cells of the fuel cell. In the case of close proximity, the supply of the oxidant is shut off, and the surface of the oxidant electrode is covered without any gaps, so that waste due to evaporation of the liquid fuel when the fuel cell is stopped, and the fuel cell due to the liquid fuel remaining in the cell It is possible to suppress the deterioration of the components constituting the. When the cells are moved away from each other, the oxidant can be supplied to the oxidant electrode, and the power generation of the fuel cell can be started.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, common constituent elements are denoted by the same reference numerals, and detailed description thereof will be appropriately omitted in the following description.

  The fuel cell according to the embodiment of the present invention can be applied to a small electric device such as a mobile phone, a portable personal computer such as a notebook, a PDA (Personal Digital Assistant), various cameras, a navigation system, and a portable music player. In particular, it is useful in a fuel cell that has a high operating voltage and uses a relatively large number of unit cells of a fuel cell such as a notebook personal computer and is mounted in a plane.

(First embodiment)
The configuration of this embodiment will be described. FIG. 1 is a plan view of the fuel cell 100 of the present embodiment, and FIGS. 2 and 3 are cross-sectional views taken along line AA ′ of FIG.

In this embodiment, two planar stacks in which four unit cells shown in FIG. 1 are arranged are stacked. In this laminated structure, the oxidant electrodes face each other, and by adjusting the distance between the two planar stacks, the state in which the oxidant electrode is exposed (FIG. 2) and is covered with a sealing material without any gaps ( 3) or vice versa, the state can be switched from the state where the oxidant electrode is covered without a gap to the state where it is exposed. During power generation, the oxidant is supplied to the oxidant electrode in the state shown in FIG. 2, and when power generation is stopped, the oxidant electrode is covered without gaps in the state shown in FIG. To do.
Details of each part will be described below.

  The fuel cell 100 shown in FIGS. 1, 2, and 3 includes a fuel cell body including a cell stack portion 456 (FIG. 1) and a reservoir tank 1386 (FIG. 1), and a fuel cartridge 1361 (FIG. 1). The fuel cartridge 1361 is a container that is detachably provided on the fuel cell main body and holds liquid fuel supplied to the cell stack portion 456 via the server tank 1386.

  A single cell structure 101 which is a minimum unit constituting a fuel cell includes a solid electrolyte membrane 114, and a fuel electrode 102 and an oxidant electrode 108 disposed on different surfaces of the solid electrolyte membrane 114. The fuel is supplied directly. As will be described later, the fuel electrode 102 and the oxidant electrode 108 have a structure in which a catalyst layer including carbon particles supporting a catalyst and a solid electrolyte is provided on a substrate. Moreover, although not shown in figure, the collector for taking out electric power from a fuel cell is connected to each electrode.

  In the planar cell stack, a plurality of single cell structures 101 are arranged in a plane, and four single cell structures 101 are arranged here. The cell stack unit 456 is formed by stacking the planar cell stack in such a manner that the oxidant electrodes 108 face each other in a direction perpendicular to the plane (hereinafter referred to as a normal direction). When the base 110 of the oxidizer electrode 108 faces each other, the concave and convex portions on the surface thereof mesh with each other, and have a cross-sectional shape that complements the concave and convex portions. In addition, since the surface of one base 110 is provided with a sealing material 435 that functions as a sealing member, the surface of the oxidant electrode 108 is covered and sealed without gaps, and the supply of the oxidant can be blocked. It has become.

  In the planar cell stack, four unit cells are embedded in a concave portion provided on one surface of the support plate 437 and the support plate 439 so that the oxidant electrode 108 is on the front side. The support plate 437 and the support plate 439 function as a casing that supports the single cell structure 101, and the single cell structure 101 is supported by these support plates so that the oxidant electrode 108 is exposed. A fuel container 811 provided in common to the four cells is adjacent to the fuel electrode 102.

  In the fuel cell 100, the support plate 437 is fixed to one end of the support rod 436, and the support plate 439 is penetrated through the support rod 436 by a screw hole in the peripheral portion. The support bar 436 can rotate around its own central axis independently of the support plate 437. Here, since the pitch of the screw holes of the support plate 439 is equal to the pitch of the male screw cut on the side surface of the support rod 436, the support plate 439 can move on the support rod 436 by the rotation of the support rod 436, The interval between the two support plates is adjustable from a close contact state to a predetermined distance. Thereby, the interval between the single cell structure 101 supported by the support plate 437 and the single cell structure 101 supported by the support plate 439 is adjusted. The support bar 436 is rotated by a motor 434, and the direction of movement of the support plate 439 is determined by the rotation direction of the motor 434. By this operation, it is possible to obtain a state where the oxidant electrode 108 is covered without a gap and a state where the oxidant electrode 108 is exposed. The motor 434 is fixed to the support bar 436 via the connection portion 438. The motor 434, the support rod 436, and the connection portion 438 function as an interval adjusting unit that adjusts the interval between the oxidant electrodes 108 of the single cell structure 101.

  Although not shown, a stopper is provided at the end of the support bar 436 so that the support plate 437 and the support plate 439 cannot be detached from the support bar. Although not shown in the figure, it is also possible to fix the two support plates at a predetermined interval by providing a lock mechanism. Further, as a developed form, the surface of the support plate 437 or the support plate 439 on which the oxidant electrode 108 is exposed and the surface of the support plate 437 or the support plate 439 facing the oxidant electrode 108 are contacted. An electric terminal or a switch that opens and closes by pressing can be provided for detecting the presence or absence. When an electrical terminal is provided, the presence / absence of contact between the oxidant electrode and the support plate facing each other can be detected by measuring the resistance between the electrical terminals. When the switch is provided, the contact can be detected by observing the conduction state of the electric circuit connected to the switch. In addition, an operation state detection unit can be provided, and these electric terminals and switches can be connected to be used for operation control of the fuel cell 100.

  Various functions are realized by automatically controlling the motor 434. For example, it is determined whether or not the oxidant electrode 108 is exposed at the start of operation, and the support plates are moved closer to or away from each other according to the result, thereby blocking the supply of the oxidant to the oxidant electrode 108 and A fuel cell system that automatically supplies the fuel can be obtained.

  In the state where the support plates are closest to each other as shown in FIG. 3, the support plate having the sealing material 435 is in close contact with the oxidant electrode 108 facing, and the surface of the oxidant electrode 108 is covered without any gap. Supply of the oxidizing agent to the electrode 108 is interrupted. Here, the sealing material 435 is used for each single cell structure 101. However, even if a single sealing material is shared by a plurality of single cell structures 101, the effect of this embodiment can be obtained in the same manner.

  The sealing material 435 has an area that covers the surface of the oxidant electrode 108 of the single cell structure 101 without a gap and is elastically deformable. By the shielding with the sealing material 435, the supply path of the oxidant can be reliably blocked.

  The material of the sealing material 435 is preferably a material having resistance to liquid fuel. Examples of such materials include elastomers such as ethylene propylene rubber and silicone rubber. When the sealant 435 is made of ethylene propylene rubber, an ethylene / propylene copolymer (EPM) or an ethylene / propylene / third component copolymer (EPDM) can be used. Further, the sealing material 435 may be vulcanized rubber. More specifically, the sealing material 435 may be a silicone rubber shaped like the surface of the oxidizer electrode 108.

  By using the above-mentioned material as the material of the sealing material 435, the liquid fuel in the fuel container 811 permeates through the fuel electrode 102, the solid electrolyte membrane 114, and the oxidant electrode 108 in this order and evaporates to the outside of the single cell structure 101. And it can suppress reliably that liquid fuel is consumed or a liquid fuel solution becomes low concentration. Further, the components of the fuel cell 100 are not deteriorated by the remaining liquid fuel.

  Next, electrical connection between the planar cell stack 459 and the planar cell stack 460 will be described. The four single cell structures 101 constituting the planar cell stack 459 and the planar cell stack 460 are electrically connected to each other by connection electrodes 431. The plurality of single cell structures 101 in the cell stack unit 456 may be connected in series or may be connected in parallel. Moreover, it can also be set as the structure which combined the serial connection and the parallel connection. The connection electrode 431 is a conductive member, and for example, stainless steel or titanium can be used as the material thereof.

  In this embodiment, the configuration in which two planar cell stacks each including four single cell structures 101 are stacked in the normal direction has been described. However, the number of single cell structures 101 included in one planar cell stack is described. The number of stacked layers is not particularly limited, and can be appropriately determined according to the purpose of use of the fuel cell 100, the applied equipment, and the like.

  With the configuration described above, in this embodiment, the surface of the oxidant electrode 108 can be exposed or covered without a gap by changing the distance between the stacked planar stacks. During power generation, an oxidant is supplied to the exposed surface of the oxidant electrode 108, and when stopped, the oxidant supply is blocked by covering the surface of the oxidant electrode 108 without any gaps. In the present embodiment, since the fuel hardly evaporates from the oxidant electrode 108 when the power generation is stopped, the waste of the fuel is small. Further, at the time of stoppage, the fuel component gas does not remain on the oxidant electrode 108 side, so there is no possibility of deterioration of components such as the current collector due to the oxide (by-product) of the residual gas.

  In the fuel cell 100, other components are not particularly limited, and for example, the configurations and materials described below can be used.

  As the material of the support plate 437 and the support plate 439, any material can be used as long as it can secure insulation around the plurality of single cell structures 101 and has resistance to fuel. For example, resins such as polyethylene, polyetheretherketone (PEEK), polyacetal (POM: polyoxymethylene) can be used. If the surface is coated with a resin or the like, a metal can be used.

  As the fuel, methanol, ethanol, other alcohols, ethers such as dimethyl ether, or organic liquid fuels such as liquid hydrocarbons such as cycloparaffins can be used. In the practice of the present invention, these fuels can be used as a stock solution or an aqueous solution thereof.

  There are various methods for supplying fuel, but the following methods will be described as typical ones. The fuel cell main body includes a fuel container 811, a fuel supply pipe 1111, a fuel supply pipe 458, a fuel recovery pipe 1113, a reservoir tank 1386, and a pump 1117. Although not shown in FIGS. 1 to 3, the fuel cell main body has an oxidant electrode side waste liquid recovery pipe that recovers water generated by a cell reaction at the oxidant electrode of the single cell structure 101 in the reservoir tank 1386. .

  The fuel is supplied from the reservoir tank 1386 to the fuel container 811 by the pump 1117 through the fuel supply pipe 1111, and is supplied from here to the fuel electrode 102 of the single cell structure 101. Since the fuel container 811 communicates with the plurality of single cell structures 101, the fuel can be evenly supplied to all the single cell structures 101. Of the fuel, the one that has not been used for the cell reaction and the water generated by the cell reaction are recovered from the fuel recovery pipe 1113 to the reservoir tank 1386 and supplied again from the fuel supply pipe 1111 to the fuel container 811.

  At least a part of the fuel supply pipe 1111 and the fuel recovery pipe 1113 is constituted by an extendable tube 457 that expands or contracts. As the expandable tube, use of an elastic material such as bellows or silicone can be used. Moreover, you may use the flexible tube which consists of the raw material which does not necessarily extend / contract. By using such a pipe, it becomes possible to supply fuel stably without being affected by the movement of the support plate 437 and the support plate 439.

Next, the single cell structure 101 used in this embodiment will be described.
The solid electrolyte membrane 114 is preferably a membrane having high hydrogen ion conductivity and is chemically stable and has high mechanical strength. Organic polymers having polar groups such as strong acid groups such as sulfone groups and phosphoric acid groups and weak acid groups such as carboxyl groups are suitable as materials. Specific examples of these organic molecules include aromatic condensation polymers, sulfone group-containing perfluorocarbons, carboxyl group-containing perfluorocarbons, and the like.

  The fuel electrode 102 has a structure in which a fuel electrode side catalyst layer 106 containing carbon particles supporting a catalyst and a solid electrolyte is provided on a substrate 104. The oxidant electrode 108 has basically the same configuration, and has an oxidant electrode side catalyst layer 112 on the substrate 110 (lower side in the figure). As the catalyst, metals such as platinum and ruthenium and alloys thereof are preferably used. The catalysts used for the fuel electrode side catalyst layer 106 and the oxidant electrode side catalyst layer 112 may be the same or different from each other.

  Even if the solid electrolyte contained in the fuel electrode side catalyst layer 106 and the oxidant electrode side catalyst layer 112 is the same material as the solid electrolyte membrane 114 or a different material, the effect of the present invention is not affected. A plurality of solid electrolytes may be used.

  The material constituting the substrate 104 and the substrate 110 is preferably a conductive porous material such as a sintered metal, a foamed metal, or a metal fiber sheet. Since these materials have low resistivity, they can also be used as current collector materials, and the substrate can also serve as a current collector. Further, the material of the base 104 and the material of the base 110 may be the same or different.

  In this embodiment, the case where each single cell structure 101 has a separate solid electrolyte membrane 114 has been described, but a plurality of fuel electrodes 102 are provided on one surface of one solid electrolyte membrane 114, and An oxidant electrode 108 may be provided on the other surface so as to face each fuel electrode 102.

  Next, the control system of the fuel cell 100 shown in FIGS. 1, 2, and 3 will be described with reference to FIGS. 4 and 5. FIG. 4 is a diagram showing the configuration of a control system that controls the introduction of gas into the oxidant electrode 108 of the fuel cell 100. FIG. 5 is a flowchart showing an example of the operation of the fuel cell 100 when the operation of the fuel cell 100 is stopped.

  In FIG. 4, fuel cell 100 further includes an ammeter 461 that measures the current value of the fuel cell, an operating state detection unit 462, a control unit 463, and a capacitor 464 in addition to cell stack unit 456. The operation state detection unit 462 detects the power generation state in the cell stack unit 456 based on the current value measured by the ammeter 461. From this detection result, it can be determined whether the fuel cell is operating or is stopped. In accordance with this determination, the fuel cell 100 is started or stopped in step 101 or step 105 of FIG. Based on the above determination, after detecting whether or not the surface of the oxidant electrode 108 is covered in step 102, the control unit 463 controls the separation and approach operation of the support plate 439 by the motor 434.

  In FIG. 4, the capacitor 464 is used as a driving power source for the motor 434 until the fuel cell 100 is started. The capacitor 464 stores electricity when the fuel cell 100 is driven. The power source is not limited to the capacitor 464. Any secondary battery that can store electricity while the fuel cell is operating, or various primary batteries may be used instead of the capacitor 464 as long as it functions as a motor-driven power source until the fuel cell is started.

Next, the operation method of the control system will be described.
When the fuel cell 100 is activated (YES in S101), it is determined whether or not the sealing material 435 is in contact with the surface of the oxidant electrode 108 (S102). When the sealing material 435 is in contact with the surface of the oxidant electrode 108 (YES in S102), the motor 434 is driven and the support plate 439 is moved away from the surface of the support plate 437 facing (S103). The sealant 435 on both surfaces of the support plate 437 and the support plate 439 is separated from each other surface by this operation. As a result, the oxidant is supplied to the oxidant electrode 108, and the fuel cell 100 starts power generation (S104).

  If the sealing material 435 is not in contact with the surface of the oxidant electrode 108 in step 102 (NO in S102), step 103 is omitted and the process proceeds to step 104. When it is determined in step 105 that the fuel cell 100 is to be stopped, in step 106, the sealing material 435 and the surface of the oxidant electrode 108 are brought into contact with each other, the supply of the oxidant is cut off, and the fuel cell 100 is stopped.

  Next, effects of the fuel cell 100 shown in FIGS. 1 to 5 will be described. The fuel cell 100 shown in FIGS. 1 to 5 is configured to be able to adjust the distance between the fuel cell planar stacks. Accordingly, when the fuel cell 100 is not operated, the supply of oxygen can be shut off by covering the surface of the oxidant electrode 108 with a support plate having a sealing material facing the surface without any gap when the fuel cell 100 is not operated. . As a result, fuel evaporation when the fuel cell 100 is not in use can be prevented, so that it is possible to avoid wasteful consumption of liquid fuel and reduction in concentration of liquid fuel. Moreover, drying of the solid electrolyte membrane 114 can also be suppressed.

  In the control method of the present embodiment, when the fuel cell 100 is stopped, almost no gas remains in the oxidant electrode 108. Therefore, even if the fuel cell 100 stops and the temperature of the fuel cell 100 decreases, There is no negative pressure in the air flow path due to the contraction of the residual gas. Therefore, the physical deterioration of the joint part of the cell stack and the solid electrolyte membrane-catalyst electrode composite caused by this phenomenon hardly occurs. Further, since almost no gas remains, there is almost no possibility that methanol in the residual gas reacts with oxygen to generate by-products such as formaldehyde, formic acid, and methyl formate. Therefore, it is very unlikely that these by-products will contact and degrade the current collector material at start-up or be released to the outside.

(Second embodiment)
In the first embodiment, the oxidant electrodes 108 are arranged to face each other and directly contact each other. However, as shown in FIGS. 6 and 7, a support plate 433 is provided between the oxidant electrodes 108. It is also possible to provide a configuration. Here, the support plate 433 functions as a shielding member, and the sealing material 435 is disposed on both surfaces thereof so as to be fitted into the concave portion of the base 110 of the oxidant electrode 108 facing each other without a gap.

  Further, as the support rod 436, as shown in FIG. 8, the one having a first screw portion 447 and a second screw portion 448 cut in the length direction on the surface is used. The pitch of the first screw portion 447 is smaller than the pitch of the second screw portion. A support plate 437 is fixed to one end of the support bar 436 in a state in which the support bar 436 can be rotated about the central axis, and a first threaded portion 447 is penetrated by a female screw having the same pitch as this threaded portion. A support plate 433 having holes at two positions on the peripheral edge is passed through. Similarly, the support plate 439 which has the through-hole which cut the internal thread of the same pitch as this screw part in the peripheral part 2 is penetrated to the 2nd screw part 448. Here, the length of the first screw portion 447 of the support bar 436 is set to a length that allows the support plates to be in close contact with each other, as shown in FIG. Further, the screw holes of each support plate are positioned so that the oxidant electrode 108 can be covered without any gaps by matching the irregularities when the support plates are closest to each other. A stopper is fixed to the end of the support rod 436 on the second screw portion 448 side so that the support plate 439 does not come off the support rod 436.

  In the present embodiment, when the fuel cell is stopped from a state in which one surface of the oxidant electrode 108 is covered with the sealing material 435 without a gap, the state is shifted to a state in which one surface of the oxidant electrode 108 is exposed and power generation is possible. Will be described. When the motor 434 is driven and the support bar 436 is rotated in a direction in which the support plate 433 and the support plate 439 move away from the support plate 437, the oxidant electrode 108 supported by the support plate 437 is gradually exposed. Further, since the pitch of the first screw portion 447 is smaller than the pitch of the second screw portion 448, the distance between the support plate 433 and the support plate 439 also gradually increases, and the oxidizing agent supported by the support plate 439. The pole 108 is also exposed. When the support plate 437, the support plate 433, and the support plate 439 are at predetermined intervals, the motor 434 is stopped, and an oxidant is supplied to start power generation.

  Here, the support plate 433 can move in the direction of the central axis of the support bar 436 along the first screw portion 447 having the same pitch as the pitch of the screw holes of the support plate 433, but the second screw portion 448 Cannot move along. Accordingly, the support plate 433 automatically stops at the end point of the first screw portion 447 even if the motor 434 is driven. The support plate 439 also hits a stopper (not shown) near the end point of the second screw portion 448 and automatically stops. Therefore, if the length of each screw portion is set to the interval between the support plates that are always used, it is possible to automatically obtain a constant interval between the support plates. Furthermore, more stable operation can be realized by applying a lock for fixing each support plate at a predetermined position.

  In addition, when power generation in the cell stack unit 456 is stopped, the motor 434 is rotated in the direction opposite to that at the start of power generation. As a result, the support plate 433 and the support plate 439 are closest to the support plate 437, the surface of the oxidant electrode 108 is covered with the sealant 435 without any gap, and the supply of the oxidant is cut off. Can do.

(Third embodiment)
In the above embodiments, the support plate is not necessarily arranged so that the oxidant electrodes 108 face each other, and the surface of the oxidant electrode faces the back surface of the support plate as shown in FIGS. 9 and 10. The distance between the opposing oxidant electrode 108 and the fuel electrode 102 may be adjustable.

  Also in this embodiment, for example, as in the second embodiment, the support rod 436 having a two-step pitch as shown in FIG. 8 is used, and the motor 343 is fixed to the first screw portion 447 side. . In this embodiment, the support plate 433 is fixed to one end of the support rod 436 so as to be rotatable around the central axis of the support rod 436, and the support plate 437 and the support plate 439 are respectively connected to the first screw portion 447 and On the second screw portion 448, the support rod 436 is moved in the central axis direction. The pitch of the first screw portion 447 is smaller than the pitch of the second screw portion 448. Here, the length of the first screw portion 447 of the support bar 436 is set to a length that allows the support plates to be closest to each other, as shown in FIG. In addition, the position of the screw hole of each support plate is a position where each oxidant electrode 108 is covered without a gap when each support plate is closest. A stopper (not shown) is fixed to the end of the support rod 436 on the second screw portion 448 side so that the support plate 439 does not come off the support rod 436.

  In the present embodiment, a case will be described in which the state is changed from a state where the surface of the oxidant electrode 108 is covered without a gap to a state where the oxidant electrode is exposed and power can be generated. When the motor 434 is driven and the support plate 437 and the support plate 439 are rotated away from the support plate 433, the oxidant electrode 108 supported by the support plate 437 is gradually exposed. Further, since the pitch of the first screw portion 447 is smaller than the pitch of the second screw portion 448, the distance between the support plate 437 and the support plate 439 also gradually increases, and the oxidant electrode supported by the support plate 439. 108 is also exposed. When the support plate 433, the support plate 437, and the support plate 439 reach a predetermined interval, the motor 434 is stopped, and an oxidant is supplied to start power generation.

  Here, the support plate 437 can move along the first screw portion 447 having the same pitch as the pitch of the screw holes of itself, but cannot move along the second screw portion 448. Accordingly, the support plate 437 automatically stops at the end point of the first screw portion 447 even if the motor 434 is driven. The support plate 439 also hits the stopper near the end point of the second screw portion 448 and automatically stops. Therefore, if the length of each screw portion is set to the interval between the support plates that are always used, it is possible to automatically obtain a constant interval between the support plates.

  When stopping the cell stack unit 456 in the power generation state, the motor 434 is rotated in the direction opposite to that at the start of power generation. As a result, the support plate 437 and the support plate 439 are closest to the support plate 433, and the surface of the oxidant electrode 108 is covered with the sealing material 435 without any gap, and power generation can be stopped.

(Fourth embodiment)
In the embodiments so far, the motor is used for moving the support plate, but an electromagnetically driven actuator can also be used.
FIGS. 11 and 12 show the configuration of the third embodiment, in which an actuator 440 is used instead of the support bar 436 and the motor 434. Also, the vertical direction coincides with the actual vertical direction.

  The support plate 433, the support plate 437, and the support plate 439 move in a direction toward or away from each other by the operation of the actuator 440, and due to these movements, the state in which the oxidant electrode 108 is covered without a gap and the oxidant electrode 108 are An exposed state can be obtained.

The operation of the actuator 440 will be described with reference to FIG.
FIG. 13A and FIG. 13B are cross-sectional views schematically showing the configuration of the actuator 440. As shown in FIGS. 13A and 13B, the actuator 440 includes a magnet 441, a coil 442 that is movable by the magnet 441, and a holding unit that is fixed in contact with the magnet 441 and holds the coil 442. 443. FIG. 13A shows a state where the coil 442 that is not energized is in contact with the magnet 441. This state is the state of the actuator 440 in the state where the oxidant electrode is covered without a gap as shown in FIG. Each support plate is stabilized in this state by its own weight. FIG. 13B shows a state where the coil 442 is separated from the magnet 441 and is energized in a direction in which repulsive force acts on the magnet (a power source used for energization is not shown). This state is the state of the actuator in the state where the oxidant electrode of FIG. 11 is exposed, and the support plate 437 and the support plate 439 are located away from the support plate 433 and the support plate 437 facing each other against gravity.

  The position of each support plate in a state where the oxidant electrode 108 is exposed, that is, the distance between the support plate 437 and the support plate 433, and the distance between the support plate 437 and the support plate 439 are the voltages applied to the actuator 440. It can be determined by adjusting.

  In addition to the electromagnetic coupling method shown here, there are a method that uses expansion and contraction by applying an electric field of a polymer material, and a method that changes the state manually, depending on the application of the fuel cell. Any one may be selected.

  In this embodiment, the configuration in which two actuators 440 are provided in one cell stack portion 456 is illustrated, but the number and arrangement of the actuators 440 can be appropriately selected according to the battery configuration.

  Various functions are realized by automatically controlling the actuator 440. For example, it is possible to automate the operation of approaching and separating the support plates depending on whether the fuel cell is in operation or stopped. Further, it is possible to obtain a fuel cell system in which the oxidant is automatically supplied by judging the separation and close contact of the support plate at the start of operation and automatically shuts off the oxidant at the time of stoppage.

(Fifth embodiment)
In the fuel cell described in the fourth embodiment, gravity is used to hold each support plate in the closest state. In this embodiment, the opening and closing of the support plate 437 relative to the support plate 433 and the opening and closing of the support plate 439 relative to the support plate 437 are performed by a combination of the actuator 440 and the elastic member, and the position of the support plate is not related to gravity. It can be used regardless of the orientation.

  14 and 15 are cross-sectional views schematically showing the configuration of the fuel cell according to this embodiment. FIG. 14 shows a state where the surface of the oxidant electrode 108 is exposed in the cell stack portion 456. FIG. 15 shows a state in which the surface of the oxidant electrode 108 is in close contact with the sealing material on the surface of the support plate due to the proximity of the facing support plate and is covered without a gap.

  In the fuel cell shown in FIGS. 14 and 15, a spring 432 connecting the support plate 433 and the support plate 437 is provided on the side surface of the actuator 440. Similarly, a spring 432 connecting the support plate 437 and the support plate 439 is provided on the side surface of the actuator 440. As the spring 432, a spring having a spring constant that is a natural length in a state where the support plate 433 and the support plate 437 are in close contact with each other (FIG. 15) is selected.

  In the fuel cell shown in FIGS. 14 and 15, when a current flows through the coil 442 constituting the actuator 440, a magnetic field is generated inside the coil 442. The polarity of the magnetic field is reversed depending on the direction of the current, and an attractive force or a repulsive force acts between the coil 442 and the magnet 441. In this embodiment, the direction of the current and the arrangement of the magnets are set so that a repulsive force acts on the coil 442 and the magnet 441 during conduction. Therefore, when a current is conducted to the coil 442 in the state of FIG. 15, the coil 442 is separated from the magnet 441, and the spring 432, which was originally a natural length, extends. As a result, the support plate 439 is moved away from the support plate 437 and away from the support plate 433 and the support plate 437, and the oxidizing agent is supplied to the exposed surface of the oxidizing agent electrode 108 (FIG. 14). When energization of the coil 442 is stopped, the spring 432 returns to its natural length due to the restoring force, and the coil 442 approaches the magnet 441. As a result, the support plate 439 is close to the support plate 437, the support plate 433 is close to the support plate 437, and the surface of the oxidant electrode 108 has the support member 437 having the sealant 435 and the support plate 433 also having the sealant 435. Thus, the supply of the oxidant is blocked (FIG. 15).

  In this embodiment, since the spring 432 is provided on the side surface of the actuator 440, the vertical direction of the fuel cell main body is not limited for the movement control of the support plate. Therefore, the environment in which the fuel cell of the present invention can be used is further expanded as compared with the first embodiment.

  Also in the present embodiment, as in the first embodiment, the coil 442 is energized so that the surface of the oxidant electrode 108 is covered without any gap when the fuel cell operation is stopped, and is controlled to open during operation. be able to. Therefore, it is possible to suppress the fuel component in the fuel from evaporating from the oxidant electrode 108 side while the fuel cell is stopped, and to reduce the concentration of the fuel component, and to suppress the waste of the fuel component. Further, since there is no useless space in the fuel cell at the time of stop, the current collecting member is not deteriorated by the remaining fuel.

  14 and 15 exemplify a configuration in which two springs 432 are provided per actuator 440, the number of springs 432 provided on the side surface of one actuator 440 is not particularly limited, Depending on the environment, the number may be increased until stable movement is possible.

  14 and 15 illustrate the configuration in which the spring 432 is provided on the side of the actuator 440, the spring 432 is not necessarily required, and a stretchable material such as rubber may be used. Further, the distance between the support plates in the state where the surface of the oxidant electrode is exposed (hereinafter, abbreviated as the distance between the support plates) is determined by the spring constant or the number of the springs 432 to be used. Therefore, a desired distance between the support plates can be obtained by changing the type or number of the springs 432 according to the purpose.

  The present invention has been described based on the embodiments. It is to be understood by those skilled in the art that these embodiments are merely examples, and that various modifications are possible and that such modifications are within the scope of the present invention.

  For example, in the above embodiment, the plurality of fuel electrodes 102 provided on one surface of one solid electrolyte membrane 114 and the other surface of the solid electrolyte membrane 114 are opposed to the plurality of fuel electrodes 102, respectively. It may include a plurality of oxidant electrodes 108 provided, and a pair of fuel electrode 102 and oxidant electrode 108 opposed to the single cell structure 101, and a solid electrolyte membrane 114. At this time, the plurality of single cell structures 101 can be electrically connected by connection electrodes 431 penetrating the solid electrolyte membrane 114.

1 is a plan view schematically showing a configuration of a fuel cell according to an embodiment. It is A-A 'sectional drawing of FIG. It is A-A 'sectional drawing of FIG. It is a block diagram showing typically the composition of the fuel cell concerning an embodiment. It is a flowchart of the fuel cell control system concerning an embodiment. It is sectional drawing which shows typically the structure of the fuel cell which concerns on embodiment. It is sectional drawing which shows typically the structure of the fuel cell which concerns on embodiment. It is sectional drawing which shows typically the structure of the moving mechanism of the fuel cell which concerns on embodiment. It is sectional drawing which shows typically the structure of the fuel cell which concerns on embodiment. It is sectional drawing which shows typically the structure of the fuel cell which concerns on embodiment. It is sectional drawing which shows typically the structure of the fuel cell which concerns on embodiment. 1 is a plan view schematically showing a configuration of a fuel cell according to an embodiment. It is sectional drawing which shows typically the structure of the actuator of the fuel cell concerning embodiment. It is sectional drawing which shows typically the structure of the fuel cell which concerns on embodiment. It is sectional drawing which shows typically the structure of the fuel cell which concerns on embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Fuel cell 101 Single cell structure 102 Fuel electrode 104 Base body 106 Fuel electrode side catalyst layer 108 Oxidant electrode 110 Base body 112 Oxidant electrode side catalyst layer 114 Solid electrolyte membrane 431 Connection electrode 432 Spring 433 Support plate 434 Motor 435 Seal material 436 Support Rod 437 Support plate 438 Connection portion 439 Support plate 440 Actuator 441 Magnet 442 Coil 443 Holding portion 447 First screw portion 448 Second screw portion 456 Cell stack portion 457 Telescopic tube 458 Fuel supply tube 459 Planar cell stack 460 Planar cell stack 461 Ammeter 462 Operating state detector 463 Controller 464 Capacitor 811 Fuel container 1111 Fuel supply pipe 1113 Fuel recovery pipe 1117 Pump 1361 Fuel cartridge 1386 Reservoir tank

Claims (17)

A unit cell is a fuel cell comprising at least a solid electrolyte membrane, a fuel electrode disposed on one surface of the solid electrolyte membrane, and an oxidant electrode disposed on the other surface,
The first unit cell and the second unit cell are arranged so that the oxidant electrodes face each other, and the interval adjustment is performed to adjust the interval between the first unit cell and the second unit cell. With means ,
A fuel cell characterized in that the surface of each of the oxidant electrodes has a cross-sectional shape that complements irregularities .   The first unit cell and the second unit cell are respectively supported by a first casing and a second casing that expose the oxidant electrode. Fuel cell. A unit cell is a fuel cell comprising at least a solid electrolyte membrane, a fuel electrode disposed on one surface of the solid electrolyte membrane, and an oxidant electrode disposed on the other surface,
The first unit cell and the second unit cell are arranged so that the oxidant electrodes face each other, and the interval adjustment is performed to adjust the interval between the first unit cell and the second unit cell. With means,
Fuel cells characterized by having a sealing member on at least one surface of the oxidant electrode facing each other. A unit cell is a fuel cell comprising at least a solid electrolyte membrane, a fuel electrode disposed on one surface of the solid electrolyte membrane, and an oxidant electrode disposed on the other surface,
The first unit cell and the second unit cell are arranged so that the oxidant electrodes face each other, and the interval adjustment is performed to adjust the interval between the first unit cell and the second unit cell. With means,
Fuel cells characterized in that a shielding member between the oxidant electrode facing each other.   Providing the shielding member having an unevenness on at least one of the oxidant electrode surface in the first unit cell or the oxidant electrode surface in the second unit cell and having a cross-sectional shape that complements the unevenness. The fuel cell according to claim 5, wherein A unit cell is a fuel cell comprising at least a solid electrolyte membrane, a fuel electrode disposed on one surface of the solid electrolyte membrane, and an oxidant electrode disposed on the other surface,
An oxidant electrode of the first unit cell and a fuel electrode of the second unit cell are arranged so as to face each other, and for adjusting an interval between the first unit cell and the second unit cell. With an interval adjusting means ,
The first unit cell and the second unit cell are respectively supported by a first casing and a second casing such that the oxidant electrode is exposed,
The oxidant electrode surface in the first unit cell;
In the surface of the second casing facing the oxidant electrode in the first unit cell,
Fuel cells characterized in that it has a cross-sectional shape composed of uneven complement each other. A unit cell is a fuel cell comprising at least a solid electrolyte membrane, a fuel electrode disposed on one surface of the solid electrolyte membrane, and an oxidant electrode disposed on the other surface,
An oxidant electrode of the first unit cell and a fuel electrode of the second unit cell are arranged so as to face each other, and for adjusting an interval between the first unit cell and the second unit cell. With an interval adjusting means,
Fuel cells characterized in that a shielding member at a position opposed to the oxidant electrode. 8. The fuel cell according to claim 7 , wherein the oxidant electrode surface and the shielding member have a cross-sectional shape made up of irregularities that complement each other. 9. The fuel cell according to claim 8 , wherein a sealing member is provided on at least one surface of the surface having the cross-sectional shape made of the unevenness. A support rod penetrating at least one of the first casing and the second casing;
Drive means connected to the support bar for moving at least one of the first casing or the second casing along the support bar;
The fuel cell according to any one of claims 1-9, characterized in that it comprises a. 11. The fuel cell according to claim 10 , wherein the support rod has a screw structure on a surface thereof, and the driving means applies a rotational force to the support rod. The fuel cell according to claim 10 or 11 , wherein the driving means includes a motor and connecting means for connecting the motor and the support rod. The fuel cell according to any one of claims 1 to 9 , wherein the interval adjusting means is an actuator provided in at least one of the first casing and the second casing. The actuator is an electromagnetic drive actuator, and has at least a magnet, a coil that is movable by the magnet, and a holding portion of the coil;
14. The fuel cell according to claim 13 , wherein the magnet is fixed to one of the first casing and the second casing, and the tip of the coil is fixed to the other. The fuel cell according to any one of claims 1 to 14, wherein the first unit cell and the second unit cell has a plurality obtained planar stacked structure in the plane. 16. The fuel cell according to claim 1, wherein the interval adjustment is performed based on an operation state detection unit that detects an operation state of the fuel cell and the operation state detected by the operation state detection unit. And a control unit for controlling the operation of the means. A method for controlling a fuel cell according to any one of claims 1 to 16 , comprising:
When the operation of the fuel cell is stopped, the interval unit adjusts the first unit cell and the second unit cell,
A method for controlling a fuel cell, wherein the first unit cell and the second unit cell are moved away by the interval adjusting means at the start of operation of the fuel cell.

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