JP2004119084A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent closure of air passage due to invasion of liquid water into the air passage in a fuel cell separator. <P>SOLUTION: The fuel cell comprises a separator 10B between the mutually adjoining unit cells 10A. The separator comprises the air passage S1 at least on the surface side contacting with the air pole 12 of the fuel cell and a cooling space S2 as a cooling means, on the rear side, where the air and water are supplied, and the cooling space is communicated with the air passage through a communicating hole 143 formed in the separator, and the end part on the entrance side of the air passage is closed to the supply of the air and water by a lid 145 formed in one body at the end part of the separator. Thereby, the invasion of water in liquid state into the air passage is prevented without installing any special member. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell, and more particularly to a fuel cell cooling technique using a separator interposed between unit cells of the fuel cell.
[0002]
[Prior art]
A unit cell of a PEM fuel cell as one type of fuel cell includes a fuel electrode (generally referred to as a hydrogen electrode because hydrogen gas is used as fuel) and an oxidant electrode (also a gas containing oxygen as an oxidant). Since a certain air is used, this is hereinafter referred to as an air electrode) and a solid polymer electrolyte membrane is sandwiched between the two. Each of the fuel electrode and the air electrode includes a catalyst layer containing a catalyst substance, and an electrode base material that supports the catalyst layer and has a function of transmitting a reaction gas. Further outside the fuel electrode and the air electrode, a gas flow path (generally, an electrode) for supplying hydrogen and air as reactant gas uniformly from the outside of the cell to the electrode surface and discharging an excess of the reactant gas outside the cell. Separator (connector plate) provided with a groove having an open surface side) is laminated. This separator prevents gas permeation and performs current collection for taking out the generated current to the outside. The unit cell and the separator as described above constitute one unit cell.
[0003]
In an actual fuel cell, a large number of such unit cells are stacked in series to form a stack. In such a fuel cell, in order to maintain sufficient power generation efficiency, it is necessary to keep the polymer solid electrolyte membrane in the unit cell in a sufficiently wet state. Generally, only water generated by the electrolytic reaction causes moisture to be generated. Because of the shortage, means for supplying humidified water to each unit cell is required. In addition, since the amount of heat substantially corresponding to the generated electric power is generated by the electrolytic reaction, a cooling means for preventing the fuel cell body from excessively heating up is provided.
[0004]
Various types of fuel cell cooling means have been conventionally proposed. As one of these methods, a configuration is adopted in which a nozzle for jetting water is provided in an air manifold for sending air as an oxidant to the air electrode, and water is jetted into the air sent to the gas flow path and mixed in advance. In some cases, cooling is performed using latent heat generated when water evaporates by heating in a gas flow path. In this method, water, which must be supplied to the cell because it is necessary to keep the unit cell wet, is supplied along with the flow of air that also needs to be supplied to the air electrode side. It is based on the idea that it is reasonable to use this water for cooling.
[0005]
In the fuel cell system adopting the above-described method, the applicant has disclosed in Japanese Patent Application No. 2002-54839 according to the earlier application that the air in which water is injected and mixed in the air manifold is connected to the communication space from the cooling space formed in the separator. To supply air to the air flow path. In this method, the unit cells are cooled by the latent heat of water evaporating by the heat of the unit cells transmitted to the cooling space, and the vaporized water is supplied to the air flow path together with the air. Thereby, while cooling the unit cell via the separator, the blockage of the flow path due to the intrusion of liquid water or mist-like water into the air flow path is prevented. That is, in the case of the fuel cell device having the above-described structure, the air and water supplied to the cooling space are used for latent heat cooling of the heat generated during power generation of the fuel cell. Then, a part of the water supplied in a liquid state evaporates in the cooling space and is supplied together with the air as water vapor from the communication hole to the air flow path, the air is used for the reaction of the fuel cell, and the water vapor is humidified. Used for
[0006]
In the case of employing the above-described supply method, if air and water are supplied to the air flow path in the same manner as the cooling space, the air flow path may be blocked by the water supplied in a liquid state. The supply of air and water to the air flow path is limited to the cooling space only, and the supply of air and water to the air flow path is to be supplied to the air flow path together with the air in the form of water vapor as the supply through the cooling space. desirable.
[0007]
[Problems to be solved by the invention]
By the way, since the air flow path and the cooling space in the separator are alternately arranged adjacent to each other, the inlet side of the air flow path also has an inlet portion of the cooling space with respect to the air manifold that supplies air and water. Since they are positioned so as to be cut and sandwiched, it is practically impossible to cover the inlet side of these air flow paths with a single member even if the air flow is to be closed against the supply of air and water. Therefore, it is not surprising that a method of closing the inlet of each air flow path with some kind of padding is conceivable, but such a method significantly increases the man-hours for manufacturing the fuel cell separator, and is not practical. is there.
[0008]
In order to solve the above-described problems, the present invention closes the inlet side of the air flow path in the separator in a method without increasing the number of manufacturing steps, thereby reducing the supply of air and water to the fuel cell. Accordingly, it is an object of the present invention to provide a fuel cell capable of supplying air and water vapor to an air flow path through a cooling space.
[0009]
[Means for Solving the Problems]
The object is to provide a fuel cell in which a separator is arranged between unit cells adjacent to each other, wherein the separator is provided on an air flow path provided on at least a surface side in contact with an air electrode of the unit cell, and provided on a back side. And cooling means for cooling the unit cells by latent heat of water evaporating by the heat of the unit cells transmitted to the cooling space, wherein the cooling space is formed in a separator. It is communicated with the air flow path through the communication hole, and the inlet end of the air flow path is closed to the supply of air and water by a lid integrally formed at the end of the separator. This is achieved by a configuration that
[0010]
In this configuration, it is effective that the separator includes a space defining member that defines a cooling space, and the lid is formed at an end of the space defining member. Specifically, the space defining member of the separator is formed by bringing a pair of plate members made of a press-formed product of a conductive metal plate material into contact with each other in a plate surface direction, and cooling between the two plate members. A space is defined, and a lid is formed by bending an end of one of the plate-like members. In this case, it is effective that the space defining member of the separator has a configuration in which a channel narrowing portion is formed by bending the other end of one plate-like member. More specifically, the one plate-shaped member has a wavy bent portion formed by bending to protrude the plate surface and extending by traversing the plate-shaped member, and a crest of a wavy bent portion at a longitudinal end. A valley portion sandwiched between the valley portions is formed by bending so as to be inclined in the direction of the hill portion, and has an inclined portion whose tip is flush with the hill portion (same plane), and is corrugated in cooperation with the other plate-shaped member. A cooling space is defined inside the portion, and the inlet side end of the air flow path is closed with the inclined portion as a lid.
[0011]
[Action]
In the configuration described in each claim of the present invention, air and water supplied to guide the air electrode of the fuel cell directly enter the air flow path by the lid covering the inlet end. And is supplied exclusively to the cooling space. Then, the water supplied to the cooling space is heated by the heat transmitted from the cell to the separator to be in a water vapor state, and is supplied to the air flow path through the communication hole of the separator riding on the air flow to wet and cool the air electrode. Used for Excess air and steam entering the air flow path are discharged from the lower opening of the air flow path of the separator and the air electrode. During this time, the latent heat cooling action of removing heat from the separator is caused by the evaporation of water by heating in the cooling space.
[0012]
In addition, air and water that have not entered the air flow path are discharged from the opening at the end of the cooling space of the separator. However, in the case of the flow path having the flow path narrowing portion, water in a liquid water state stays at the flow path narrowing portion. This causes a phenomenon of blocking the flow path, and this water acts to prevent direct discharge of air from the cooling space. Therefore, in the one having the flow path constricted portion, substantially all the air supplied to the cooling space is sent to the air flow path and then discharged through the air flow path. In this case, the liquid water that fulfills the function of closing the air is sequentially drained by the lower water remaining in the narrow channel portion being pushed by the upper water and dropping as water droplets.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, FIG. 1 shows a configuration example of a vehicle fuel cell system according to an application of the present invention. This system includes a fuel cell stack 1, a fuel supply system (shown by a two-dot chain line) 2 for supplying hydrogen as fuel to the fuel cell stack 1, and air for supplying oxidizing gas to the fuel cell stack 1. An air supply system (shown by a dashed-dotted line in the figure) 3, a water supply system (shown by a solid line in the figure) 4 for supplying water mainly for cooling to required parts of the system including the fuel cell stack 1, and power generation. It comprises an electric load system (shown by a broken line in the figure) 5 as a load.
[0014]
The fuel cell stack 1 is configured by stacking a large number of plate-shaped unit cells in the plate thickness direction. As shown in a horizontal cross section in FIG. 2 and a vertical cross section in FIG. 3, the unit cell 10 includes a unit cell 10A and a separator 10B. For convenience of description, FIG. 2 also shows adjacent unit cells, and FIG. 3 does not show the unit cells. The unit cell 10A has a solid polymer electrolyte membrane 11 sandwiched between an air electrode 12 and a fuel electrode 13, and the separator 10B has a two-piece thin plate, although a detailed structure thereof will be described later. The four metal plates 14 and 15 are surrounded by insulator frames 16 and 17. The separator 10B is formed with hydrogen passages L1 and L2 communicating with the hydrogen supply passage 20 of the fuel supply system 2 and an air passage S1 communicating with the air manifold 34 of the air supply system 3 via the cooling space S2. The fuel cell stack 1 is disposed in a housing connected to the air manifold 34 with the hydrogen flow paths L1 and L2 oriented horizontally and the air flow path S1 oriented vertically.
[0015]
Returning to FIG. 1, the fuel supply system 2 is configured as a storage unit 21 for hydrogen using a hydrogen storage alloy as a fuel, and is provided in a hydrogen supply path 20 connecting the storage unit 21 and the fuel cell stack 1. A hydrogen pressure regulating valve 23 for adjusting the supply pressure to 1 and a hydrogen supply solenoid valve 24 for controlling the supply cutoff are inserted in series. In connection with the fuel supply system 2, the fuel cell stack 1 is provided with a hydrogen exhaust path 27 for extracting hydrogen therefrom as needed, and in the middle thereof, a hydrogen exhaust solenoid valve 29 for opening and closing the exhaust path, A hydrogen exhaust check valve 28 for preventing the intake of outside air is interposed. The hydrogen supply path 20 is provided with a hydrogen primary pressure sensor 22 and a secondary pressure sensor 25 for measuring gas pressures before and after pressure regulation by a hydrogen pressure regulating valve 23.
[0016]
The air supply system 3 includes a duct in which an air supply fan 31 that sends outside air to the air manifold 34 via a filter and a heater is arranged, a duct that connects the fuel cell stack 1 to the storage unit 21 of the hydrogen storage alloy, and a storage unit 21. It is composed of a duct connecting the water condenser 46 and a discharge path for discharging used air from the water condenser 46 through a filter to the outside air. The air supply system 3 further includes an intake air temperature sensor 32 that monitors the temperature of air supplied to the fuel cell stack 1 upstream of an air supply fan for operating a heater as needed, An exhaust temperature sensor 37 attached to the downstream duct and monitoring the temperature of the air exhausted from the fuel cell stack 1 is also provided.
[0017]
The water supply system 4 supplies the water sent from the water tank 40 by the water injection pump 41 to the air manifold 34 by the water injection nozzle 45 around the water tank 40, and supplies the water to the hydrogen storage alloy in the storage unit 21. The circulation path is configured to directly return to the water tank 40 water supplied by the storage nozzle 46 and collected and generated by the fuel cell stack 1 and water generated by condensation in the water condenser 46. In the middle of the water passage from the water injection pump 41 constituting the supply side of the circulation path to the water injection nozzle 45, a direct injection water electromagnetic valve 43 for adjusting the injection amount is interposed, and a nozzle is provided on the suction side of the water injection pump 41. A filter 42 for preventing clogging of 45 is inserted. Similarly, a storage solenoid valve 47 for adjusting the injection amount is inserted in the middle of the water passage from the water injection pump 41 to the storage nozzle 46. The recovery side of the circulation path includes a water path returning from the fuel cell stack 1 to the water tank 40, and a water path returning from the water condenser 46 to the water tank 40 via the pump 44. The water tank 40 is provided with a water temperature sensor 47 and a water level sensor 48, so that the water temperature and the water level of the tank can be monitored.
[0018]
The electric load system 5 of the fuel cell is constituted by a lead wire connected from the fuel cell stack 1 via the relay 53 to the inverter 51 for controlling the motor 52. In this system, a secondary battery composed of a storage battery is used as a driving power source for ancillary equipment such as an air supply fan 31, a water condenser 46 fan, a water injection pump 41, a water tank 40 freezing countermeasure heater, and various solenoid valves of a fuel cell device. A battery 54 is provided, and the secondary battery 54 is connected in parallel to the fuel cell. This secondary battery 54 is used for accumulating the regenerative current of the motor 52 and for supplementing the output when the output of the fuel cell is insufficient.
[0019]
In the fuel cell system having such a configuration, the hydrogen supply electromagnetic valve 24 is closed, and hydrogen is stored in the hydrogen storage alloy by the supply of hydrogen gas from a filling path (not shown). The supply of water to the water supply system 4 is performed by opening the water supply electromagnetic valve 48 and supplying water to the water tank 40. Then, in the power generation state, the hydrogen supply solenoid valve 24 is opened to supply the hydrogen occluded in the hydrogen storage alloy under the pressure regulation by the hydrogen pressure regulating valve 23 to the fuel cell stack 1 while the air supply fan 31 is activated, An operation of sending air to the fuel cell stack 1 via the air manifold 34 is performed. In this power generation state, the direct injection water electromagnetic valve 43 is opened while operating the water direct injection pump 41 of the water supply system 4 continuously or intermittently as necessary, and water is injected from the water injection nozzle 45 into the air manifold 34. As a result, an operation of mixing water into the air supplied to the fuel cell stack 1 in a mist state is performed. This water enters the cooling space S2 from the upper opening of the cooling space S2 shown in FIG. 2 and FIG. 3 of each separator of the fuel cell stack 1 together with the air, is vaporized, passes through the air flow path S1, and becomes the air electrode of each cell. Except for those supplied to the 12 side, they are discharged to the lower part of the housing from the lower opening constituting the discharge part of the cooling space S2, and collected in the water tank 40.
[0020]
The air and the water in the water vapor state, which are sent to the fuel cell stack 1 and heated by the fuel cell stack 1 as described above, enter the storage 21 of the hydrogen storage alloy via the duct from the lower portion of the housing, and After being heated, the air is guided to a water condenser 46 through a duct, and is separated into dry air and condensed water. The dried air is discharged to the outside air through a filter, and the condensed water is passed through a pump 44 to a water tank. Return to 40. Further, the water that has passed through the fuel cell stack 1 in a liquid state returns directly to the water tank 40.
[0021]
The feature of this system is that the air flow path S1 and the cooling space S2 in the fuel cell stack 1 can be arranged in a unified distribution path, and air and water can be distributed at the same time. There is no need to provide.
[0022]
Next, a detailed configuration of the separator 10B inserted between the unit cells 10A of each unit cell 10 of the fuel cell stack 1 will be described. As shown in FIG. 4 in a disassembled state, the separator 10B includes a pair of current collectors for contacting the air electrode 12 and the fuel electrode 13 (see FIG. 2) of the unit cell 10A to take out current. 14 and 15 and frames 16 and 17 that are superimposed on them and support the unit cell 10A. In this embodiment, the current collecting members 14 and 15 are formed of a thin metal plate, for example, having a plate thickness of about 0.1 mm. The constituent metal is a metal having conductivity and corrosion resistance, for example, a metal obtained by subjecting a stainless steel, a nickel alloy, a titanium alloy, or the like to a corrosion resistance conductive treatment.
[0023]
One of the current collecting members 14 is formed of a horizontally long rectangular plate material and forms a part of a space defining member that defines the cooling space S2, and is formed by press working that partially raises the plate surface within a predetermined range. A plurality of protrusions 141 are formed by extrusion. These convex portions 141 are arranged in a continuous straight line, parallel to the longitudinal sides (short sides in the illustrated form) of the plate material, and at equal intervals, so as to completely traverse the plate surface. Is composed. At the upper end of the current collecting member 14 in the vertical direction, the peak portion of the wavy bent portion 140, that is, the valley portion sandwiched between the convex portions 141 is bent so as to be inclined in the peak direction, so that the tip portion is flush with the peak portion. An inclined portion 145 is formed to function as a lid according to the subject of the present invention. Furthermore, each convex part 141 is flattened by crushing its lower part in the thickness direction. The cross-sectional shape of the portion other than the flattened portion 141 ′ of the inclined portion 145 and the convex portion 141 is roughly shown as a rectangular wave-shaped cross section in FIG. 2 for convenience. It is more practical to make the shape slightly wider.
[0024]
Referring to FIG. 2, a groove-shaped space S1 defined between convex portions 141 and having an open side facing unit air electrode 12 of unit cell 10A allows air to flow to air electrode 12 side, as described later in detail. It is used as an air flow path for circulation. The plane of the top 142 of each convex portion 141 is a contact portion with which the air electrode 12 contacts. The groove-shaped space S2 defined on the back side of the convex portion 141 is used as a cooling space (flow path in this embodiment), which will be described later in detail. A large number of through holes 143 that penetrate the current collecting member 14 are formed so that the air flow path S1 and the cooling space S2 partially communicate with each other. The opening positions of these through holes 143 are arbitrary, but both side surfaces of the convex portion 141 are common sense. Further, long elliptical holes 144 that are long in the vertical direction are formed near both ends in the horizontal side (long side in the illustrated form) direction of the current collecting member 14. When the separator 10B is laminated by stacking the current collecting member 14 on the current collecting member 15 and the frames 16 and 17, the oblong holes 144 define the hydrogen passages L1 and L2 that align and penetrate these members. Constitute.
[0025]
Returning to FIG. 4, the other current collecting member 15 is formed of a rectangular plate that matches the current collecting member 14 so as to constitute the other of the space defining members that define the cooling space S2. Are extruded. The convex portion 151 has a flat top 152 (see FIG. 2) and a substantially rectangular cross-sectional shape similarly to the case of the above-mentioned convex portion 141. However, in this case, the convex portion 151 It is provided intermittently in the vertical direction. In other words, the protrusions 151 are arranged such that the horizontal (longer side) pitch is aligned with the pitch of the convexes 141 of the current collector 14, and the vertical (short side) pitch is set to an appropriate interval. It is a round or rectangular projection. The left half section in FIG. 2 shows a cut section at the arrangement portion of the projections 151, and the right half section shows a cut section at the arrangement portion. The vertical and horizontal spaces S3 formed between the projections 151 constitute a planar space whose side facing the fuel electrode 13 of the unit cell 10 is open, and is a hydrogen flow path through which hydrogen as fuel flows. . The plane of the top 152 of the projection 151 serves as a contact portion with which the fuel electrode 13 contacts. Further, the rear side of the convex portion 151 is a short cylindrical space S4 in which the side facing the current collecting member 14 is open, and is fitted to the space S2 of the current collecting member 14, and as a result, the cooling space S2 is interposed. Thus, a configuration is provided in which both ends are open to the long side of the plate material. Like the current collecting member 14, the current collecting member 15 also has a long oval hole 153 formed in the short side direction near both ends in the long side direction, and is overlapped with the current collecting member 14 and the frames 15 and 16. When the separators 10B are stacked together, the hydrogen passages L1 and L2 are formed to penetrate these members in alignment. In this embodiment, the convex portion 151 has a short columnar shape that intermittently abuts on the fuel electrode 13 with a small area, thereby forming a hydrogen passage S3 vertically and horizontally between the columnar convex portions 151, The purpose is to suppress stagnation and stagnation of the flow of hydrogen gas. In addition, since the contact area of the hydrogen gas with the fuel electrode 13 is increased by doing so, improvement in power generation efficiency can be expected.
[0026]
The current collecting members 14 and 15 having the above-described configuration are overlapped and fixed such that the respective convex portions 141 and 151 are both on the outside. At this time, the plate surface portion on which the convex portions 141 and 151 are not formed, that is, the back surface of the hydrogen flow path S3 and the back surface of the air flow path S1 are in contact with each other, and are in a state where they can be energized mutually. Further, by overlapping the current collecting members 14 and 15, a cooling space in which the space S2 and the space S4 are combined is formed between them. When the unit cell 10A is fitted to the current collecting member 14, the open surface side of the space S1 is closed to form a tubular air flow path, and a part of the wall surrounding the flow path is formed by the air electrode 12. Will be. Then, air and water are supplied from the air flow path S1 to the air electrode 12 of the unit cell 10A. Similarly, when the unit cell 10A is fitted to the current collecting member 15, the open surface side of the space S3 is closed to form a planar hydrogen flow path, and a part of the wall surrounding the flow path is formed by the fuel electrode 13. Will be done. Then, hydrogen is supplied from the fuel passage S3 to the fuel electrode 13 of the unit cell 10A.
[0027]
Frames 16 and 17 are respectively superposed on the current collecting members 14 and 15 having the above-described configuration. As shown in FIGS. 3 and 4, the frame 16 superposed on the current collecting member 14 has substantially the same outer shape as that of the current collecting member 14, and the vertical frame 161 on both sides is divided into upper and lower horizontal frame portions 162, 163. The lower horizontal frame portion 163 is lower than the lower side of the horizontal frame portion 163 so as not to be flush with the lower sides of the vertical frame portions 161 and the current collecting members 14 and 15 on both sides. Are slightly shifted upward so as to be positioned upward. At the center surrounded by these frames, a window 164 for accommodating the convex portion 141 of the current collecting member 14 is defined. Also, the frame body 16 is formed with oval holes 165 at positions and shapes corresponding to the oval holes 144 of the current collecting member 14 near both ends. The horizontal frame portions 162 and 163 of the frame body 16 and the vertical frame portion 161 of the portion to which they are connected are made thinner than the entire vertical frame portion 161. The horizontal frame portions 162 and 163 on the surface on which the power is collected are located at positions corresponding to the convex portion forming range of the current collecting member 14, and the surface retreated from the contact surface with the current collecting member 14 over the entire short side direction. Has formed. Therefore, when the frame 16 is overlaid on the current collecting member 14, the convex portion 141 of the current collecting member 14 contacts the air electrode 12 of the unit cell 10 </ b> A in the window 164 and faces the horizontal frame portions 162 and 163. In the part that does, it has a relationship that abuts them. Thus, between the current collecting member 14 and the frame 16, the convex portion 141 of the current collecting member 14 and the inner surface of the horizontal frame portion 162 are located at the upper part, and the convex portion 141 of the current collecting member 14 is located at the window 164. As a large number of tubular spaces surrounded by the convex portion 141 of the current collecting member 14 and the inner surface of the horizontal frame portion 163 at the lower portion of the air electrode 12 surface of 10A, the upper end extends to the inner surface of the horizontal frame portion 162 at the tip of the lid portion 145. An air flow path S1 which is closed by the contact and has a lower end opened between the horizontal frame portion 163 and the current collecting member 14 and extending in the vertical direction is defined.
[0028]
The frame 17 superimposed on the current collecting member 15 is formed in a frame shape having a smaller vertical dimension than the frame 16, and in this case, an opening larger than the window 171 is formed in the main body 170 in the lateral direction. The height of this opening defines the height of the window 171, and the width of the opening is set to a width that matches the width between the outer ends of the oblong holes 153 at both ends of the current collecting member 15. A pair of vertical frame portions 172 are provided near both ends of the opening in the width direction. The width between the vertical frame portions 172 defines the width of the window 171, and the width defined by the vertical frame portions 172 and the width of the opening of the main body portion 170 is an oblong hole at both ends of the current collecting member 15. An elongated hole 173 having a size matching the width of the elongated hole 153 and substantially matching the position and shape of the elongated hole 153 is formed. The vertical frame portion 172 is made thinner than the main body portion 170. Due to the relationship between the thicknesses, the vertical frame portion 172 is provided at the position where the vertical frame portion 172 is provided on the surface on which the current collecting member 15 is overlapped. A surface that is recessed from the contact surface by an amount corresponding to the height of the portion 151 is formed. Therefore, when the frame 17 is superimposed on the current collecting member 15, the projection 151 of the current collecting member 15 contacts the vertical frame 172 in the vertical frame 172, and the fuel electrode of the unit cell 10 </ b> A in the window 171. 13 comes into contact. In the portion sandwiched between the long holes 173 in this manner, a planar hydrogen flow path S3 that is uniformly formed so as to cover the projection 151 is formed.
[0029]
Further, a detailed configuration not shown in the drawings will be described. Preferably, the cross-sectional area of the flow path forming the cooling space S2 is set to gradually decrease from the upper side to the lower side. With such a configuration, the pressure loss of the air flowing from the cooling space S1 to the air flow path S2 can be reduced. Such a flow path configuration can be realized by appropriately setting the height and / or width of the convex portion 141 of the current collecting member 14.
[0030]
In addition, hydrophilic processing is performed on the inner wall surfaces of the air passage S1 and the cooling space S2 as necessary. Specifically, this treatment is performed such that the contact angle between the inner wall surface and water is 40 ° or less, preferably 30 ° or less. As a treatment method, a method of applying a hydrophilic treatment agent to the surface is employed. Examples of the treatment agent to be applied include polyacrylamide, polyurethane resin, titanium oxide (TiO2), and the like. As another hydrophilic treatment, a treatment for roughening the roughness of the metal surface may be mentioned. For example, plasma processing is an example. The hydrophilic treatment is preferably performed on a portion where the temperature is highest. For example, the cooling space inner wall surface F1 on the back side of the top 142 of the protrusion 141 in contact with the unit cell 10A, and the air flow path on the front side of the protrusion 141 It is desirable that the processing is preferentially performed in the order of the side wall surface F2, the back side cooling space side wall surface F3, and the air flow path bottom surface F4. Further, the inner wall surface F5 of the projection 151 constituting a part of the cooling space S2 may be subjected to a hydrophilic treatment. By performing the hydrophilic treatment, wetting of the inner wall surface is promoted, and the effect of the latent heat cooling of water is improved.
[0031]
The separators 10B are configured by holding the current collecting members 14 and 15 by the frames 16 and 17 configured as described above, and the fuel cell stack 1 is configured by alternately stacking the separators 10B and the unit cells 10A. . On the upper surface of the fuel cell stack 1 thus stacked, openings of a large number of cooling spaces S2 are arranged side by side at intervals as shown in FIG. Air and water intakes are formed with openings of the same arrangement in the stacking direction at intervals corresponding to the thickness. On the lower surface of the fuel cell stack 1, as shown in FIG. 6, openings at the lower ends of the flow path constrictions S 2 ′ of the cooling space S 2 are provided in the discharge section of the rectangular air flow path in the lateral direction at intervals. At the same time, a water discharge section having openings of the same arrangement arranged in the stacking direction is formed at intervals corresponding to the thickness of the horizontal frame portion 163 of the frame 17 and the frame 16.
[0032]
The configuration according to the subject of the present invention in each unit cell of the fuel cell having the above configuration can be summarized by referring to the longitudinal section of the separator shown in FIG. 3 and the upper surface of the separator shown in FIG. The side end is closed to the supply of air and water by the separator 10B. Since the separator 10B includes the current collecting members 14 and 15 as space defining members that define the cooling space S2, the inlet-side end of the air flow path S1 is closed by the current collecting member 14. The current collecting members 14 and 15 of the separator 10B are formed by bringing a pair of plate members made of a press-formed product of a conductive metal plate material into contact with each other in the plate surface direction, and a cooling space S2 is formed between both plate members. At the same time, the one end of the plate-shaped member, that is, the end of the current collecting member 14 is bent to close the inlet end of the air flow path S1. The current collecting member 14 has a wavy bent portion 140 formed by bending to protrude the plate surface and extending through the plate member, and a valley portion sandwiched between the peaks of the wavy bent portion 140 at a vertical end. Has an inclined portion 145 formed by bending to incline in the direction of the hill, and the tip thereof is flush with the hill, and cooperates with the other plate-like member 15 to form a cooling space S2 inside the wavy bent portion 140. And the inclined end 145 closes the inlet end of the air flow path S1.
[0033]
The fuel cell stack having such a configuration operates as schematically shown in FIG. 7 by supplying air, water, and hydrogen to each unit cell. In this case, since the air and water are uniformly supplied from the upper surface of the stack, the opening of the air flow path S1 is provided with a current collecting member 14 so that water does not directly enter the air flow path S1. It is closed by an upper slope 145. As shown in the drawing, the air and water supplied to the cooling space S2 enter the upper portion of the cooling space in a state where water droplets are mixed in a mist state in the air flow (hereinafter, this state is referred to as a mixed flow). In the steady operation state of the fuel cell, the mixed flow in the cooling space S2 is heated because the unit cell 10A generates heat by the reaction. The water droplets in the mixed flow adhere to the wall surface of the cooling space S2 by the hydrophilic treatment, and evaporate by heating to generate a latent heat cooling effect of removing heat from the wall surface. The water that has thus become steam enters the air flow path S1 together with the air whose flow is indicated by the outline arrow in the figure as shown by the shaded arrow in the figure, as shown by the shaded arrow in the figure, and flows to the air electrode 12 side of the unit cell 10A. It adheres and wets the cathode 12. Excess air and steam entering the air flow path S1 are discharged from the lower opening of the air flow path S1 below the fuel cell stack.
[0034]
On the other hand, the air and water that have not entered the air flow path S1 are discharged from the lower opening of the cooling space S2 below the fuel cell stack as it is, but due to the action of the flow path narrowing portion S2 ′. The water in the liquid state flowing down the wall reaches the channel narrowing portion S2 'and stays there, causing a phenomenon of blocking the channel by capillary action, and this water causes direct discharge of air from the cooling space S2. It acts to hinder. Therefore, substantially all of the air supplied to the cooling space S2 is sent into the air passage S1, and then discharged from the fuel cell stack via the air passage S1. In addition, the liquid water that fulfills the function of plugging air is drained sequentially by the lowermost water staying in the channel narrowing portion S2 'being pushed by the upper water and dropping as water droplets.
[0035]
On the other hand, the supply of hydrogen to the fuel flow path S3 is performed by using one of the hydrogen flow paths L1 and L2 (see FIG. 2) penetrating both sides of each unit cell 10 in their stacking direction. It is performed from the fuel flow path S3 connected to it through the space between them. Thus, hydrogen is supplied to the fuel electrode 13 of the unit cell 10A. On the fuel electrode 13 side, surplus hydrogen that has entered the fuel flow path S3 is discharged to the opposite hydrogen flow path, and is discharged or recovered by a system pipe connected to the hydrogen flow path.
[0036]
As described in detail above, according to this embodiment, since the inlet end of the air flow passage S1 is closed by the lid 145 integrally formed on the end of the separator 10B, the inlet end of each air flow passage S1 is closed. This leads to an increase in the number of manufacturing steps for filling the end portion, an increase in the number of components, and an increase in the number of components, such as adding a complicated lid member to the separator 10B to close the inlet end of the cut air flow path S1. Without closing, the inlet end of the air flow path S1 can be closed with a simple configuration. Thus, supply of air and water vapor to the air flow path S1 via the cooling space S2 is realized, and blockage of the air flow path S1 by water, such as when air and water are directly supplied to the air flow path S1. Eliminate concerns.
[0037]
In addition, since the end of the space defining member 14 that defines the cooling space S2 is the lid 145, the air flow can be prevented without affecting other members such as the frames 16 and 17 that constitute the separator 10B. The entrance end of the road S1 can be closed. Further, since the lid portion 145 is formed by bending the plate-shaped member 14, it is possible to perform the processing simultaneously with the processing of forming the cooling space S2 in the space defining member 14 made of a metal material constituting the separator 10B. An increase in man-hours can be prevented. In addition, since the both ends of the plate-like member 14 constituting the space defining member have the lid 145 formed by bending and the flow path narrowing portion S2 ', the plate material is used when the space defining member is pressed. Can be balanced at both ends, thereby preventing warpage in the plate surface of the plate material, that is, a phenomenon in which one side of the plate material shrinks and deforms into a fan shape, thereby improving the press working accuracy. In addition, since the lid 145 is formed as an inclined portion, the cooling space S2 and the wavy bent portion 140 that defines the air flow path S1 are smoothly connected to each other. Shape.
[0038]
As described above, the embodiments have been exemplified for the understanding of the present invention. However, the present invention is not limited to the illustrated embodiments, and various specific configurations may be adopted within the scope of the claims. It can be implemented with modification.
[0039]
【The invention's effect】
According to the first aspect of the present invention, since the inlet end of the air flow path is closed by the lid integrally formed with the end of the separator, the inlet end of each air flow path is closed. It can be easily performed without increasing the number of manufacturing processes such as padding, adding a complicated lid member to the separator to close the inlet end of the cut air flow path, and complicating the structure and increasing the number of parts. With such a configuration, the inlet end of the air flow path can be closed. This achieves the supply of air and water vapor to the air flow path through the cooling space, and eliminates the possibility that the air flow path is blocked by water as in the case of directly supplying air and water to the air flow path. Can be.
[0040]
According to the second aspect of the present invention, the other end of the space defining member that defines the cooling space is a lid at the inlet end of the air flow path, thereby forming another member constituting the separator. The inlet end of the air flow path can be closed without affecting the air flow.
[0041]
Furthermore, according to the third aspect of the present invention, since the lid at the end on the inlet side of the air flow path is formed by bending a plate-shaped member, the space defining member made of a metal material constituting the separator can be used. The processing can be performed simultaneously with the processing for forming the cooling space, and an increase in the number of processing steps can be prevented.
[0042]
According to the configuration of the fourth aspect, the space defining member has the lid portion formed by bending and the flow path constriction portion at both ends of the plate-like member constituting the space defining member. The stress applied to the plate at the time of pressing can be balanced at both ends. As a result, it is possible to prevent a warpage in the plate surface of the plate material, that is, a phenomenon in which one side of the plate material shrinks and deforms into a fan shape, and press working accuracy is improved.
[0043]
Further, according to the configuration of the fifth aspect, the lid of the plate-shaped member has an inclined portion, so that the lid has a shape that is smoothly connected to the wavy bent portion that defines the cooling space and the air flow path. Therefore, the plate member can be formed into a shape excellent in press workability.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a fuel cell system according to an application of the present invention.
FIG. 2 is a partial cross-sectional view of a unit cell according to an embodiment of the present invention.
FIG. 3 is a partial longitudinal sectional view of the unit cell of the embodiment.
FIG. 4 is an exploded perspective view of a separator constituting the unit cell of the embodiment.
FIG. 5 is a partial top view of the unit cell according to the embodiment.
FIG. 6 is a partial bottom view of the unit cell according to the embodiment.
FIG. 7 is a schematic diagram illustrating a mechanism of cooling and draining by the separator of the embodiment.
[Explanation of symbols]
10A Unit cell 10B Separator 12 Air electrode 14, 15 Conductive member (space defining member, plate member)
140 Wavy bent part 143 Communication hole 145 Inclined part (lid)
S1 Air flow path S2 Cooling space (cooling means)
S2 'Channel narrowing part

Claims (5)

In a fuel cell in which a separator is arranged between adjacent unit cells,
The separator includes an air flow path provided on at least a surface side of the unit cell in contact with the air electrode, and a cooling space provided on the back side and supplied with air and water, and the unit cell transmitted to the cooling space. Cooling means for cooling the unit cells by latent heat of water evaporated by heat of
The cooling space is communicated with the air flow path through a communication hole formed in the separator, and the inlet end of the air flow path is provided with a lid integrally formed at the end of the separator to supply air and water. A fuel cell characterized by being closed. The fuel cell according to claim 1, wherein the separator includes a space defining member that defines a cooling space, and the lid is formed at an end of the space defining member. The space defining member of the separator is formed by bringing a pair of plate members made of a press-formed product of a conductive metal plate material into contact with each other in a plate surface direction, and defines a cooling space between both plate members. 3. The fuel cell according to claim 2, wherein the lid is formed by bending an end of one of the plate members. 4. The fuel cell according to claim 3, wherein the space defining member of the separator has a flow path constriction formed by bending the other end of one of the plate members. 5. The one plate-shaped member has a wavy bent portion formed by bending to protrude the plate surface and extending by traversing the plate-shaped member, and a valley portion sandwiched between ridges of the wavy bent portion at a longitudinal end. Has an inclined portion formed by bending to incline in the direction of the mountain portion, and the tip is flush with the mountain portion,
The fuel according to claim 3 or 4, wherein a cooling space is defined inside the wavy bent portion in cooperation with the other plate-shaped member, and the inlet side end of the air flow path is closed with the inclined portion as a lid. battery.

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