Fuel cell stack

Abstract

To stabilize a power generation performance.SOLUTION: A fuel cell stack includes: a cell stacked body with a plurality of power generation cells and a dummy cell disposed adjacent to power generation cells in an edge part of the cell stacked body; and an end unit disposed adjacent to the dummy cell, the end unit having a gas supply port and a gas discharge port communicating with a gas supply flow path and a gas discharge flow path of the cell stacked body, respectively. An end-part power generation cell has a first communication hole forming the gas supply flow path. The dummy cell has a second communication hole forming the gas supply flow path. The first and second communication holes are formed so that an extension surface formed by extending an opening surface of the second communication hole toward the first communication hole and an opening surface of the first communication hole do not match.SELECTED DRAWING: Figure 7A

Description

Technical Field

[0001] The present invention relates to a fuel cell stack.

Background Art

[0002] In recent years, in order to enable more people to access affordable, reliable, sustainable, and advanced energy, technological development related to fuel cells that contribute to energy efficiency has been carried out. As a technology related to this type of fuel cell, conventionally, a fuel cell stack has been known in which a dummy cell is arranged on the dry side of the fuel cell stack, and liquid water contained in the fuel gas supplied through the fuel gas supply passage is separated from the fuel gas on the downstream side of the dummy cell (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the fuel cell stack described in Patent Document 1 above, there is a risk that the liquid water contained in the fuel gas separates in the fuel gas supply passage before reaching the dry-side dummy cell and flows into the power generation cell, resulting in unstable power generation performance.

Means for Solving the Problems

[0005] A fuel cell stack according to one aspect of the present invention includes a plurality of power generation cells that are power generation bodies stacked in a predetermined direction, and a dummy cell that is a non-power generation body disposed adjacent to an end power generation cell located at one end in the predetermined direction among the plurality of power generation cells. A cell stack body is provided with a gas supply passage through which a reaction gas is supplied and a gas discharge passage through which the reaction gas is discharged, both extending along the predetermined direction, and a gas passage communicating the gas supply passage and the gas discharge passage. An end unit is disposed adjacent to the dummy cell and is provided with a gas supply port communicating with the gas supply passage and a gas discharge port communicating with the gas discharge passage. A first communication hole constituting the gas supply passage is opened in the end power generation cell, and a second communication hole constituting the gas supply passage is opened in the dummy cell. The first communication hole and the second communication hole are provided such that an extended surface obtained by extending the opening surface of the second communication hole in the predetermined direction toward the first communication hole does not coincide with the opening surface of the first communication hole.

Advantages of the Invention

[0006] According to the present invention, it is possible to suppress liquid water contained in the reaction gas supplied through the gas supply port from flowing into the power generation cell, and stable power generation performance can be obtained.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6A

Figure 6B

Figure 7A

Figure 7B

Figure 8

Figure 9A

Figure 9B

Figure 10

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 10. The fuel cell stack according to the embodiment of the present invention is a main component of a fuel cell. The fuel cell can be mounted on a vehicle, for example, and generate electric power for driving the vehicle. First, the overall configuration of the fuel cell stack will be schematically described.

[0009] FIG. 1 is a perspective view schematically showing the overall configuration of a fuel cell stack 100 according to the present embodiment. Hereinafter, for convenience, three axial directions orthogonal to each other as shown in the figure are defined as the front-rear direction, the left-right direction, and the up-down direction, and the configuration of each part will be described according to this definition. The lower side in the up-down direction corresponds to, for example, the gravitational direction. The front-rear direction corresponds to the stacking direction of the fuel cell stack 100. The front-rear direction and the left-right direction are not necessarily the same as the front-rear direction and the left-right direction of the vehicle. For example, the front-rear direction in FIG. 1 may be the front-rear direction of the vehicle or the left-right direction.

[0010] As shown in FIG. 1, the fuel cell stack 100 includes a cell stack 101 formed by stacking a plurality of power generation cells 1 in the front-rear direction, and end units 102 disposed at both front and rear ends of the cell stack 101, and has an overall substantially rectangular parallelepiped shape. Although illustration is omitted, the periphery of the cell stack 101 is covered by a substantially rectangular parallelepiped case. The length of the cell stack 101 in the left-right direction is longer than the length in the up-down direction. In FIG. 1, for convenience, a single power generation cell 1 is shown.

[0011] The power generation cell 1 includes an electrode assembly 2 (UEA; Unitized Electrode Assembly) having a joined body including an electrolyte membrane and electrodes, and separators 3, 3 disposed on both front and rear sides of the electrode assembly 2 and sandwiching the electrode assembly 2. The electrode assembly 2 and the separator 3 are alternately arranged in the front-rear direction. The electrode assembly 2 can also be referred to as a membrane electrode structure or a membrane electrode member.

[0012] FIG. 2 is a cross-sectional view of the main part at the center in the left-right direction of the cell stack 101 (a cross-sectional view taken along line II-II in FIG. 1). As shown in FIG. 2, the separator 3 has a front plate 3F and a rear plate 3R which are a pair of thin metal plates with a corrugated cross-section. The front plate 3F extends in the up-down, left-right directions and has a front surface 3Fa and a rear surface 3Fb. The rear plate 3R extends in the up-down, left-right directions and has a front surface 3Ra and a rear surface 3Rb. The rear surface 3Fb of the front plate 3F and the front surface 3Ra of the rear plate 3R facing each other are joined together at their outer peripheries by welding or the like. Thereby, the front plate 3F and the rear plate 3R are integrally coupled. A conductive material excellent in corrosion resistance is used for the separator 3, and for example, stainless steel, titanium, a titanium alloy, etc. can be used.

[0013] Inside the separator 3 surrounded by the front plate 3F and the rear plate 3R, that is, between the rear surface 3Fb of the front plate 3F and the front surface 3Ra of the rear plate 3R, a cooling flow path PAw through which a cooling medium flows is formed. The power generation surface of the fuel cell 1 is cooled by the flow of the cooling medium. For example, water can be used as the cooling medium. The surfaces (front surface 3Fa and rear surface 3Rb) of the separator 3 facing the electrode assembly 2 are configured in a concavo-convex shape by press molding or the like so as to form a gas flow path between the separator 3 and the electrode assembly 2. More specifically, the separator 3 has a pair of front and rear convex portions 31 protruding toward the electrode assembly 2, and a pair of front and rear concave portions 32 configured in a concave shape and continuous with the pair of front and rear convex portions 31.

[0014] The pair of front and rear convex portions 31 abut against the front surface 2a and the rear surface 2b of the electrode assembly 2. When the fuel cell stack 100 is assembled, a compressive load F is applied in the front-rear direction to the cell laminate 101, and this compressive load F is retained after the assembly of the fuel cell stack 100 is completed. Therefore, a predetermined surface pressure due to the compressive load F acts on the electrode assembly 2 in the front-rear direction via the convex portions 31.

[0015] Between the front surface 2a of the electrode assembly 2 and the rear plate 3R of the separator 3 facing the front surface 2a, an anode flow path PAa through which a fuel gas flows is formed by the concave portion 32. Between the rear surface 2b of the electrode assembly 2 and the front plate 3F of the separator 3 facing the rear surface 2b, a cathode flow path PAc through which an oxidant gas flows is formed by the concave portion 32. The fuel gas is a gas containing hydrogen, and for example, hydrogen gas can be used. The oxidant gas is a gas containing oxygen, and for example, air can be used. These may be referred to as reaction gases without distinguishing between the fuel gas and the oxidant gas.

[0016] Figure 3 is a perspective view showing the schematic configuration of the electrode assembly 2. As shown in Figure 3, the electrode assembly 2 has a substantially rectangular joined body 20 and a frame 21 that supports the joined body 20. The joined body 20 is a membrane electrode assembly (MEA; Membrane Electrode Assembly). As shown in the detailed view of part A in Figure 2, the joined body 20 has an electrolyte membrane 23, an anode electrode 24 provided on the front surface 231 of the electrolyte membrane 23, and a cathode electrode 25 provided on the rear surface 232 of the electrolyte membrane 23.

[0017] The electrolyte membrane 23 is, for example, a solid polymer electrolyte membrane, and a thin film of a perfluorosulfonic acid polymer containing moisture can be used. Not limited to fluorine-based electrolyte membranes, hydrocarbon-based electrolyte membranes can also be used.

[0018] The anode electrode 24 is formed on the front surface 231 of the electrolyte membrane 23 and has an electrode catalyst layer 241 that serves as a reaction field for the electrode reaction, and a gas diffusion layer 242 provided on the front surface of the electrode catalyst layer 241 that diffuses and supplies the fuel gas. An intermediate layer (underlayer) can also be provided between the electrode catalyst layer 241 and the gas diffusion layer 242.

[0019] The cathode electrode 25 is formed on the rear surface 232 of the electrolyte membrane 23 and has an electrode catalyst layer 251 that serves as a reaction field for the electrode reaction, and a gas diffusion layer 252 provided on the rear surface of the electrode catalyst layer 251 that diffuses and supplies the oxidant gas. An intermediate layer (underlayer) can also be provided between the electrode catalyst layer 251 and the gas diffusion layer 252.

[0020] In the anode electrode 24, the fuel gas (hydrogen) supplied through the anode flow path PAa is ionized by the action of a catalyst, passes through the electrolyte membrane 23, and moves to the cathode electrode side. The electrons generated at this time pass through the external circuit and are taken out as electrical energy. In the cathode electrode 25, the oxidant gas (oxygen) supplied through the cathode flow path PAc reacts with the hydrogen ions guided from the anode electrode 24 and the electrons that have moved from the anode electrode 24, generating water. The generated water (referred to as generated water) gives an appropriate humidity to the electrolyte membrane 23, and the excess water is discharged to the outside of the electrode assembly 2 along the gas flow. The generated water on the cathode side also flows to the anode side by reverse diffusion through the electrolyte membrane 23. Therefore, generated water exists in both the anode flow path PAa and the cathode flow path PAc.

[0021] As shown in FIG. 3, the frame 21 is a thin plate having a substantially rectangular shape and is composed of a resin, rubber, or the like having insulating properties. A substantially rectangular opening 21a is provided in the central portion of the frame 21. The joined body 20 is provided so as to cover the entire opening 21a, and the peripheral portion of the joined body 20 is supported by the frame 21.

[0022] On the left side of the opening 21a of the frame 21, three through holes 211 to 213 penetrating the frame 21 in the front-rear direction are opened side by side in the vertical direction. On the right side of the opening 21a, three through holes 214 to 216 penetrating the frame 21 in the front-rear direction are opened side by side in the vertical direction. For the sake of convenience, the through holes 211 to 216 are all shown as having a substantially rectangular shape, but the shapes and arrangements of the through holes 211 to 216 are not limited to this.

[0023] As shown in FIG. 1, through holes 301 to 306 penetrating the separator 3 in the front-rear direction are respectively opened at positions corresponding to the through holes 211 to 216 of the frame 21 in the separators 3 before and after the electrode assembly 2. The through holes 301 to 306 communicate with the through holes 211 to 216 of the frame 21 respectively. By the set of the mutually communicating through holes 211 to 216 and 301 to 306, flow paths PA1 to PA6 (shown by arrows for convenience) extending in the front-rear direction through the cell stack 101 are formed. The flow paths PA1 to PA6 are sometimes called manifolds. The flow paths PA1 to PA6 are connected to a manifold outside the fuel cell stack 100.

[0024] Although illustration is omitted, the end units 102 before and after the cell stack 101 each have a plurality of plates arranged one above the other in the front-rear direction. That is, the end unit 102 has a terminal plate arranged adjacent to the cell stack 101, an insulating plate arranged outside the terminal plate in the front-rear direction, and an end plate arranged outside the insulating plate in the front-rear direction.

[0025] The terminal plate is a substantially rectangular plate-like member made of metal and has a terminal portion for taking out the electric power generated by the electrochemical reaction in the cell stack 101. The insulating plate is a substantially rectangular plate-like member made of resin or rubber having non-conductivity and electrically insulates the terminal plate and the end plate. The end plate is a plate-like member made of metal or resin configured with high strength.

[0026] The rear end unit 102 is a wet side end unit through which the reaction gas and the cooling medium pass, and the front end unit 102 is a dry side end unit through which the reaction gas and the cooling medium do not pass. In the rear end unit 102, a plurality of through holes 102a to 102f penetrating the end unit 102 in the front-rear direction are opened at positions corresponding to the through holes 211 to 216 and 301 to 306 of the cell stack 101. The through holes 102a to 102f are shown as substantially rectangular for convenience, but the shapes of the through holes 102a to 102f are not limited to this.

[0027] A fuel gas tank storing high-pressure fuel gas is connected to the through hole 102a via an ejector, an injector, etc. Fuel gas is supplied to the fuel cell stack 100 through the through hole 102a along the solid-line flow path PA1. This fuel gas is guided to the anode flow path PAa between the electrode assembly 2 and the rear plate 3R of the separator 3 through the through holes 211 and 301. The fuel gas (fuel exhaust gas) after passing through the anode flow path PAa is discharged from the through hole 102f along the solid-line flow path PA6 through the through holes 216 and 306. Note that the through hole 102a is provided on the upper side in the vertical direction (opposite to the gravity direction) than the through hole 102f.

[0028] A compressor for supplying an oxidant gas is connected to the through hole 102d, and the oxidant gas compressed by the compressor is supplied to the fuel cell stack 100 through the through hole 102d along the dotted-line flow path PA4. This oxidant gas is guided to the cathode flow path PAc between the electrode assembly 2 and the front plate 3F of the separator 3 through the through holes 214 and 304. The oxidant gas (oxidant exhaust gas) after passing through the cathode flow path PAc is discharged from the through hole 102c along the dotted-line flow path PA3 through the through holes 213 and 303.

[0029] A pump for supplying a cooling medium is connected to the through hole 102e, and the cooling medium is supplied to the fuel cell stack 100 through the through hole 102e along the dashed-dotted line flow path PA5. This cooling medium is guided to the cooling flow path PAw between the front plate 3F and the rear plate 3R of the separator 3 through the through holes 215 and 305. The cooling medium after passing through the cooling flow path PAw is discharged from the through hole 102b along the dashed-dotted line flow path PA2 through the through holes 212 and 302. The discharged cooling medium is cooled by heat exchange in a radiator and supplied again to the fuel cell stack 100 through the through hole 102e. The above is the schematic configuration of the fuel cell stack 100.

[0030] The configuration of the separator 3 will be described in more detail. FIG. 4 is a rear view of the separator 3 (a view seen from the rear). That is, FIG. 4 shows the rear surface 3Rb (FIG. 2) of the separator 3 facing the anode electrode 24 on the front surface 2a of the electrode assembly 2. The point P in the figure is the midpoint in the left-right direction and the midpoint in the up-down direction of the separator 3, and is called the center point. The left-right direction and the up-down direction in FIG. 4 correspond to the longitudinal direction and the short-side direction of the separator 3, respectively.

[0031] In FIG. 4, the region facing the joint 20 of the electrode assembly 2, that is, the region AR1 facing the power generation surface, is called the active region of the separator 3, and the region AR2 other than the active region is called the non-active region. As shown in FIGS. 2 and 4, in the active region AR1 of the separator 3, although some illustrations are omitted, a plurality of convex portions 31 (FIG. 2) project rearward at equal intervals in the up-down direction over substantially the entire region. The plurality of convex portions 31 each extend in the left-right direction while meandering, and a concave portion 32 (FIG. 2) is provided between the convex portions 31, 31 adjacent to each other in the up-down direction. An anode flow path PAa is formed between the plurality of concave portions 32 and the front surface 2a of the joint 20.

[0032] As shown in FIG. 4, on the rear surface 3Rb of the separator 3 (rear plate 3R), a plurality of bead portions for sealing, that is, metal bead seals, projecting rearward toward the frame 21 are provided. The plurality of bead portions include an outer bead portion 331, an inner bead portion 332, and an end bead portion 333.

[0033] The outer bead portion 331 extends along the periphery of the rear plate 3R so as to surround the entire through holes 301 to 306, and the whole presents a substantially rectangular shape. The end bead portions 333 are provided in the same number as the through holes 301 to 306. The plurality of end bead portions 333 each present a substantially rectangular shape and individually surround the plurality of through holes 301 to 306. The inner bead portion 332 is provided inside the outer bead portion 331. More specifically, the inner bead portion 332 extends in a zigzag manner via the outer sides in the left-right direction of the end bead portions 333 around the through holes 301, 303, 304, 306 and via the inner sides in the left-right direction of the end bead portions 333 around the through holes 302, 305. The end bead portions 333 around the through holes 302, 305 are located between the outer bead portion 331 and the inner bead portion 332.

[0034] On both the left and right sides of the active region AR1 of the separator 3, a plurality of substantially columnar embossments 341 protruding in the front-rear direction are provided. The convex portion 31, the concave portion 32, the metal bead seal, etc. are formed by pressing the rear plate 3R.

[0035] Although illustration is omitted, similarly, on the front surface 3Fa of the separator 3 (front plate 3F), a plurality of convex portions 31, concave portions 32, metal bead seals (outer bead portion 331, inner bead portion 332, end bead portion 333), etc. are formed by pressing the front plate 3F. Thereby, a cathode flow path PAc is formed between the plurality of concave portions 32 and the rear surface 2b of the joining body 20.

[0036] FIG. 5 is a cross-sectional view of a main part at the rear end of the fuel cell stack 100 including the flow path PA1 for fuel gas in FIG. 1 (a cross-sectional view taken along the line V-V in FIG. 1). As shown in FIG. 5, the cell stack 101 has a plurality of power generation cells 1 that are power generation bodies and dummy cells 10 that are non-power generation bodies. The dummy cell 10 is interposed between the last power generation cell 1 (conveniently referred to as the rear end power generation cell 1a) and the rear end unit 102. A dummy cell 10 can also be interposed between the foremost power generation cell 1 and the front end unit 102.

[0037] The dummy cell 10 has a dummy assembly 11 corresponding to the electrode assembly 2 and dummy separators 12 disposed on both the front and rear sides of the dummy assembly 11. The configuration of the dummy separator 12 is the same as that of the separator 3 of the power generation cell 1. That is, through-holes 301 to 306 having the same configuration as the separator 3 are opened in the dummy separator 12.

[0038] The dummy assembly 11 has a dummy frame 210 and a dummy junction body 200. The dummy frame 210 is configured in the same manner as the frame 21 of the power generation cell 1, except that the configurations (sizes) of the through-holes 211 and 214 for supplying reaction gas are different. Therefore, the dummy frame 210 is provided with through-holes 211a to 216a and an opening 21a similar to the through-holes 211 to 216 and the opening 21a of the frame 21.

[0039] The dummy junction body 200 is a junction body of a conductive plate and an electrode provided so as to cover the opening 21a (FIG. 3) of the dummy frame 210. The dummy cell 10 is different from the power generation cell 1 in that it does not have an electrolyte membrane 23, and power generation does not occur in the dummy cell 10. By disposing the dummy cell 10 adjacent to the end unit 102 in this way, the dummy cell 10 functions as a heat insulating layer, and a temperature drop of the power generation cell 1 can be suppressed. Note that instead of providing the dummy frame 210 and the dummy junction body 200 separately, the plate of the dummy junction body 200 may be enlarged so that the plate of the dummy junction body 200 has a function as the dummy frame 210. In FIG. 5, a single dummy cell 10 is disposed between the power generation cell 1 and the end unit 102, but a plurality of dummy cells 10 may be disposed.

[0040] FIG. 5 shows bead portions (end bead portions 333) projecting forward and backward from the front plate 3F and the rear plate 3R of the separator 3 and the dummy separator 12, respectively, for sealing. A sealing material 13 made of an elastic constituent material such as rubber or resin material is fixed to the surface of the end bead portion 333. Although illustration is omitted, the sealing material 13 is fixed not only to the surface of the end bead portion 333 but also to the surfaces of the outer bead portion 331 (FIG. 4) and the inner bead portion 332 (FIG. 4). A pressing force in the front-rear direction is applied to the sealing material 13, whereby the contact surfaces between the separator 3 and the frame 21 and between the dummy separator 12 and the dummy frame 210 and the end unit 102 can be sealed.

[0041] As shown in FIG. 4, a plurality of tunnel portions 41 are provided across the end bead portion 333 at the periphery of the through hole 301 of the separator 4 for fuel gas inflow. For example, the tunnel portions 41 are provided so as to cross the right end portion of the end bead portion 333 in the left-right direction and the lower end portion of the end bead portion 333 in the up-down direction.

[0042] FIG. 6A is a cross-sectional view showing the configuration of the tunnel portion 41 in the vicinity of the through hole 301 (a cross-sectional view taken along line A-A in FIG. 4). As shown in FIG. 6A, the front plate 3F is provided with a tunnel portion 41 convex forward, and the rear plate 3R is provided with a tunnel portion 41 convex backward. The protrusion amount of the tunnel portion 41 in the front-rear direction is smaller than the protrusion amount of the bead portion 333 in the front-rear direction. Although illustration is omitted, the tunnel portion 41 has a substantially rectangular or substantially trapezoidal cross section, and a communication flow path PA11 is formed between the front and rear tunnel portions 41, 41.

[0043] The left end of the tunnel portion 41 is located at the periphery of the through hole 301, and the left end of the communication flow path PA11 faces the through hole 301 and is opened. At the right end of the tunnel portion 41 beyond the end bead portion 333, a taper portion 411 is provided such that the protruding amount gradually decreases toward the right. At the right end of the tunnel portion 41, the protruding amount in the front-rear direction becomes 0, and the communication flow path PA11 is blocked. An outlet 410 for fuel gas is opened in the taper portion 411 of the rear plate 3R. Thereby, the through hole 301 and the anode flow path PAa behind the rear plate 3R communicate with each other via the communication flow path PA11 and the outlet 410. For this reason, the fuel gas flowing through the through hole 301 can be supplied to the anode flow path PAa via the communication flow path PA11 and the outlet 410 as shown by the arrow in FIG. 6A.

[0044] As shown in FIG. 4, a plurality of tunnel portions 42 are provided across the end bead portion 333 around the through hole 306 of the separator 3. Although illustration is omitted, the tunnel portion 42 is configured in the same manner as the tunnel portion 41 in FIG. 6A. That is, the tunnel portion 41 and the tunnel portion 42 have a symmetrical shape with respect to an axis (not shown) extending in the vertical direction passing through the center point P in FIG. 4. Therefore, an inlet 420 for fuel gas is opened in the taper portion at the left end of the tunnel portion 42 of the rear plate 3R. Thereby, the fuel gas flowing through the anode flow path PAa is guided to the through hole 306 via the inlet 420 and the communication flow path PA11 inside the tunnel portion 42.

[0045] A plurality of tunnel portions 44 are also provided across the end bead portion 333 around the through hole 304 of the separator 4 for oxidant gas inflow. For example, the tunnel portion 44 is provided so as to cross the left end portion of the end bead portion 333 in the left-right direction and the lower end portion of the end bead portion 333 in the up-down direction.

[0046] FIG. 6B is a cross-sectional view showing the configuration of the tunnel portion 44 near the through-hole 304 (a cross-sectional view taken along line B-B in FIG. 4). As shown in FIG. 6B, the front plate 3F is provided with a tunnel portion 44 that protrudes convexly forward, and the rear plate 3R is provided with a tunnel portion 44 that protrudes convexly rearward. The protrusion amount of the tunnel portion 44 in the front-rear direction is smaller than the protrusion amount of the bead portion 333 in the front-rear direction. Although illustration is omitted, the tunnel portion 44 has a substantially rectangular or substantially trapezoidal cross-section, and a communication flow path PA12 is formed between the front and rear tunnel portions 44, 44.

[0047] The right end of the tunnel portion 44 is located at the periphery of the through-hole 304, and the right end of the communication flow path PA12 faces the through-hole 304 and is opened. A tapered portion 441 is provided at the left end of the tunnel portion 44 beyond the end bead portion 333, such that the protrusion amount gradually decreases toward the left. At the left end of the tunnel portion 44, the protrusion amount in the front-rear direction becomes zero, and the communication flow path PA12 is blocked. An outlet 440 for the oxidant gas is opened in the tapered portion 441 of the front plate 3F. Thereby, the through-hole 304 and the cathode flow path PA c in front of the front plate 3F communicate with each other via the communication flow path PA12 and the outlet 440. For this reason, the oxidant gas flowing through the through-hole 304 can be supplied to the cathode flow path PA c via the communication flow path PA12 and the outlet 440, as indicated by the arrow in FIG. 6B.

[0048] As shown in FIG. 4, a plurality of tunnel portions 43 are provided in the end bead portion 333 around the through-hole 303 of the separator 3 so as to cross the end bead portion 333. Although illustration is omitted, the tunnel portion 43 is configured in the same manner as the tunnel portion 44 in FIG. 6B. That is, the tunnel portion 43 and the tunnel portion 44 have a symmetrical shape with respect to an axis (not shown) extending in the vertical direction passing through the center point P in FIG. 4. Therefore, an inlet 430 for the fuel gas is opened in the tapered portion at the right end of the tunnel portion 43 of the front plate 3F. Thereby, the oxidant gas flowing through the cathode flow path PA c is guided to the through-hole 303 via the inlet 430 and the communication flow path PA12 inside the tunnel portion 43.

[0049] Note that the configurations (number, position, shape, etc.) of the tunnel portions 41 and 44 that communicate the gas supply channels PA1 and PA4 with the anode channel PAa and the cathode channel PAc, and the tunnel portions 42 and 43 that communicate the gas discharge channels PA3 and PA6 with the anode channel PAa and the cathode channel PAc are not limited to those described above. For example, more tunnel portions 41 and 44 may be provided facing downward or obliquely downward.

[0050] As shown in FIG. 5, an axis CL1 passing through the center of the through-hole 211 of the frame 21 in the vertical and horizontal directions and an axis CL2 passing through the center of the through-hole 211a of the dummy frame 210 are located on the same axis extending in the front-rear direction. The through-holes 211 and 211a of the frame 21 and the dummy frame 210 are smaller than the through-holes 301 of the separator 3 and the dummy separator 12. For this reason, the frame 21 and the dummy frame 210 protrude more inward (toward the axes CL1 and CL2) than the separator 3 and the dummy separator 12.

[0051] In FIG. 5, for convenience, the through-hole 211 and the through-hole 211a are shown to have the same shape and size. Note that having the same size means that the opening areas of the through-holes 211 and 211a are the same as each other. In FIG. 5, since the axes CL1 and CL2 are in a straight line and the shapes of the through-holes 211 and 211a are the same as each other, the extended surface obtained by extending the opening surface along the edge of the through-hole 211a forward coincides with the opening surface of the through-hole 211.

[0052] When the through-hole 211a of the dummy cell 10 (dummy frame 210) and the through-hole 211 of the power generation cell 1 (frame 21) are set to have the same shape and size in this way, there are the following problems. That is, in this case, the liquid water (generated water or condensed water) that has flowed into the inside of the cell stack 101 together with the fuel gas through the through-hole 102a of the end unit 102 may reach the power generation cell 1 by jumping over the through-hole 211a of the dummy cell 10, as shown by the arrow in FIG. 5.

[0053] The liquid water reaching the power generation cell 1 is guided to the anode flow path PAa facing the power generation surface of the electrode assembly 2 along the flow of the fuel gas through the communication flow path PA11 (Fig. 6A) inside the tunnel portion 41. As a result, the electrochemical reaction on the power generation surface is inhibited, the power generation performance becomes unstable, and there is a risk of a decrease in power generation performance. This is also a problem in the flow path PA4 for supplying the oxidant gas as well as the flow path PA1 for supplying the fuel gas. That is, the liquid water in the flow path PA4 is guided to the cathode flow path PAc facing the power generation surface of the electrode assembly 2 along the flow of the oxidant gas through the communication flow path PA12 (Fig. 6B) inside the tunnel portion 44, and the power generation performance becomes unstable, and there is a risk of a decrease in power generation performance.

[0054] Therefore, in order to obtain stable power generation performance by providing a liquid water inflow suppression portion that suppresses the liquid water in the flow paths PA1 and PA4 from being guided to the power generation surface, the fuel cell stack 100 is configured as follows in the present embodiment.

[0055] Fig. 7A is a diagram schematically showing a first example of the liquid water inflow suppression portion, that is, the configuration of the first liquid water inflow suppression portion 51, and is a cross-sectional view including the flow path PA1 for supplying the fuel gas, similar to Fig. 5. Fig. 7B is a view of the flow path PA1 seen from the rear (view VIIB in Fig. 7A). Although illustration is omitted, the first liquid water inflow suppression portion 51 is similarly provided in the flow path PA4 for supplying the oxidant gas.

[0056] As shown in Figs. 7A and 7B, in the first liquid water inflow suppression portion 51, the through hole 211a of the dummy frame 210 is formed larger than the through hole 211 of the frame 21 and larger in the vertical direction than the through hole 102a of the end unit 102. The sizes of the through hole 211 of the frame 21 and the through hole 102a of the end unit 102 are the same. The positions of the axis CL1 of the through hole 211 and the axis CL2 of the through hole 211a are the same as each other.

[0057] In the first liquid water inflow suppression part 51, the edge part 217 of the through hole 211 of the frame 21 protrudes inward over the entire circumference from the edge part 217a of the through hole 211a of the dummy frame 210. For this reason, the extension surface 211b obtained by extending the opening surface of the through hole 211a forward is located outside the opening surface of the through hole 211, and the extension surface 211b abuts against the frame 21 of the rear end part power generation cell 1a. The edge part 217 of the through hole 211 of the frame 21 constitutes a protruding part that protrudes inward from the through hole 211a. The lower protruding part is particularly called the lower protruding part 218.

[0058] The first liquid water inflow suppression part 51 operates as follows. When liquid water flows into the flow path PA1 through the through hole 102a of the end unit 102, as shown by the arrow in Fig. 7A, a part of the liquid water that has passed through the through hole 211a of the dummy frame 210 collides with the edge part 217 (protruding part) of the through hole 211. More specifically, since the liquid water is likely to generate a downward flow due to gravity, a part of the liquid water that has passed through the through hole 211a collides with the lower protruding part 218. For this reason, as shown by the hatching in Fig. 7B, the flow of the liquid water is blocked by the lower protruding part 218.

[0059] The blocked liquid water flows downward along the communication flow path PA11 (Fig. 6A) of the dummy separator 12 and the front surface of the dummy assembly 11. Further, it is discharged to the outside of the cell stack 101 through the flow path PA6 (Fig. 1) for fuel gas discharge. Thereby, it is possible to suppress the liquid water in the flow path PA1 from being guided to the anode flow path PAa of the power generation cell 1 beyond the through hole 211 of the frame 21, and stable power generation performance can be obtained.

[0060] Fig. 8 is a diagram schematically showing a second example of the liquid water inflow suppression part, that is, the configuration of the second liquid water inflow suppression part 52, and is a cross-sectional view including the flow path PA1 for fuel gas supply and the flow path PA6 for fuel gas discharge. Although illustration is omitted, the second liquid water inflow suppression part 52 is similarly provided also in the flow path PA4 for oxidant gas supply and the flow path PA3 for oxidant gas discharge.

[0061] As shown in FIG. 8, the configuration of the flow path PA1 for fuel gas supply (the size of the through holes 211 and 211a) is the same as that of the first liquid water inflow suppression portion 51. Therefore, the through hole 211a of the dummy frame 210 of the flow path PA1 is larger than the through hole 211 of the frame 21 in the vertical direction.

[0062] On the other hand, in the flow path PA6 for discharge, the through hole 216a of the dummy frame 210 is formed smaller than the through hole 216 of the frame 21 and smaller than the through hole 102f of the end unit 102 in the vertical direction. The sizes of the through hole 216 of the frame 21 and the through hole 102f of the end unit 102 are the same. Note that the positions of the axes (not shown) of the through holes 216 and 216a are the same as each other.

[0063] The second liquid water inflow suppression portion 52 operates as follows. When liquid water flows into the flow path PA1 through the through hole 102a of the end unit 102, as shown by the arrow in FIG. 8, a part of the liquid water that has passed through the through hole 211a of the dummy frame 210 collides with the edge portion 217 (mainly the lower protruding portion 218) of the through hole 211. The flow velocity and pressure of the fuel gas in the region A indicated by the two-dot chain line on the inlet side of the flow path PA1 and the region B indicated by the two-dot chain line on the outlet side of the flow path PA4 are compared. On the inlet side, since the through hole 211a is larger than the through hole 211, the flow velocity is low and the pressure is high. On the other hand, on the outlet side, since the through hole 216a is smaller than the through hole 216, the flow velocity is high and the pressure is low. As a result, since the pressure difference between the region A and the region B increases, the flow of liquid water from the region A to the region B is promoted, and the liquid water in the flow path PA1 can be efficiently guided to the flow path PA6.

[0064] FIG. 9A is a diagram schematically showing a third example of the liquid water inflow suppression portion, that is, the configuration of the third liquid water inflow suppression portion 53, and FIG. 9B is a view of the flow path PA1 seen from the rear (arrow view IXB in FIG. 9A). Although illustration is omitted, the third liquid water inflow suppression portion 53 is similarly provided in the flow path PA4 for oxidant gas supply.

[0065] As shown in FIGS. 9A and 9B, in the third liquid water inflow suppression part 53, contrary to the first liquid water inflow suppression part 51, the through hole 211a of the dummy frame 210 is formed smaller than the through hole 211 of the frame 21 in the vertical direction and smaller than the through hole 102a of the end unit 102. The sizes of the through hole 211 of the frame 21 and the through hole 102a of the end unit 102 are the same. Note that the positions of the axis CL1 of the through hole 211 and the axis CL2 of the through hole 211a are the same as each other.

[0066] In the third liquid water inflow suppression part 53, the edge part 217a of the through hole 211a in the dummy frame 210 protrudes inward over the entire circumference from the edge part 217 of the through hole 211 in the frame 21. For this reason, the extension surface 211b obtained by extending the opening surface of the through hole 211a forward is located inside the opening surface of the through hole 211. The edge part 217a of the through hole 211a of the dummy frame 210 constitutes a protruding part that protrudes inward from the through hole 211. The lower protruding part is particularly referred to as the lower protruding part 218a.

[0067] The third liquid water inflow suppression part 53 operates as follows. When liquid water flows into the flow path PA1 through the through hole 102a of the end unit 102, as shown by the arrow in FIG. 9A, a part of the liquid water collides with the edge part 217a (mainly the lower protruding part 218a) of the through hole 211a. For this reason, as shown by the hatching in FIG. 9B, the flow of the liquid water is blocked by the lower protruding part 218a.

[0068] The blocked liquid water flows downward along the communication flow path PA11 (FIG. 6A) of the dummy separator 12 and the front surface of the end unit 102. Further, it is discharged to the outside of the cell stack 101 through the flow path PA6 (FIG. 1) for discharging fuel gas. Thereby, it is possible to suppress the liquid water in the flow path PA1 from being guided to the anode flow path PAa of the power generation cell 1 beyond the through hole 211a of the dummy frame 210, and stable power generation performance can be obtained.

[0069] In the above-described first liquid water inflow suppression section 51 and second liquid water inflow suppression section 52, a single dummy cell 10 is disposed between the power generation cell 1 and the end unit 102 (Figs. 7A, 7B, 8), but a plurality (for example, two) of dummy cells 10 may be disposed. In this case, the through-hole 211a of the front dummy frame 210 may be set to the same size as the through-hole 211 of the frame 21 positioned in front thereof, and may be made smaller than the through-hole 211a of the rear dummy frame 210.

[0070] As a result, a part of the liquid water that has passed through the through-hole 211a of the rear dummy frame 210 collides with the edge portion 217a around the through-hole 211a of the front dummy frame 210. As a result, similar to the third liquid water inflow suppression section 53, it is possible to prevent the liquid water from flowing forward beyond the through-hole 211a of the dummy frame 210 (rear dummy frame 210).

[0071] FIG. 10 is a cross-sectional view showing a modified example of the through-holes 102a and 102d for supplying reaction gas of the end unit 102. In the modified example of FIG. 10, the through-holes 102a and 102d of the end unit 102 are configured to be inclined downward such that the opening area gradually increases forward. That is, an inclined surface 102g is provided on the opening surface of the through-holes 102a and 102d. As a result, since the liquid water flows obliquely downward along the inclined surface 102g, the flow of the liquid water toward the front dummy cell 10 is promoted, and the liquid water can be efficiently guided to the flow paths PA3 and PA6 for the reaction exhaust gas via the dummy cell 10.

[0072] According to the present embodiment, the following operational effects can be obtained. (1) The fuel cell stack 100 includes a plurality of power generation cells 1 which are power generation bodies laminated in the front-rear direction, and a dummy cell 10 which is a non-power generation body disposed adjacent to a rear-end power generation cell 1a located at the rear end of the plurality of power generation cells 1. Gas supply channels PA1, PA4 for supplying reaction gas and gas discharge channels PA3, PA6 for discharging reaction gas extend along the front-rear direction respectively. A cell stack 101 is provided with gas flow channels (anode channel PAa, cathode channel PAc) that communicate the channel PA1 with the channel PA6 and the channel PA4 with the channel PA3 respectively. An end unit 102 is disposed adjacent to the dummy cell 10 and is provided with gas supply ports (through holes 102a, 102d) that communicate with the gas supply channels PA1, PA4 for gas supply and gas discharge ports (through holes 102c, 102f) that communicate with the gas discharge channels PA4, PA6 for gas discharge (Figs. 1 to 5). In the rear-end power generation cell 1a (frame 21), through holes 211 (first communication holes) that constitute the gas supply channels PA1, PA4 are opened. In the dummy cell 10 (dummy frame 210), through holes 211a (second communication holes) that constitute the gas supply channels PA1, PA4 are opened (Figs. 7A to 9B). The fuel cell stack 100 has either a first liquid water inflow suppression part 51, a second liquid water inflow suppression part 52, or a third liquid water inflow suppression part 53. The through hole 211 and the through hole 211a are provided such that an extended surface 211b obtained by extending the opening surface of the through hole 211a in the front-rear direction toward the through hole 211 does not coincide with the opening surface of the through hole 211 (Figs. 7A, 8, 9A).

[0073] With this configuration, liquid water (generated water or condensed water) that has flowed into the gas supply channels PA1, PA4 together with the reaction gas can flow through the inside of the dummy cell 10 to the gas discharge channels PA3, PA6 before reaching the power generation cell 1. As a result, it is possible to suppress the supply of liquid water to the power generation cell 1 and obtain stable power generation performance.

[0074] (2) In the first liquid water inflow suppression part 51 and the second liquid water inflow suppression part 52, the through holes 211 of the frame 21 are smaller than the through holes 211a of the dummy frame 210 (FIGS. 7A, 7B, 8). Thereby, the liquid water flowing into the gas supply channels PA1 and PA4 is blocked at the edge 217 of the through hole 211 of the frame 21 of the rear end power generation cell 1a, and it is possible to suppress the liquid water from flowing into the channels PA1 and PA4 beyond the through hole 211.

[0075] (3) In the second liquid water inflow suppression part 52, through holes 213 and 216 that form the gas discharge channels PA3 and PA6 are opened in the rear end power generation cell 1a (frame 21) (FIG. 3). In the dummy cell 10 (dummy frame 210), a through hole 216a that forms the gas discharge channels PA3 and PA6 and is smaller than the through holes 213 and 216 is opened (FIG. 8). Thereby, the difference in pressure between the region A inside the through hole 211a of the dummy frame 210 and the region B inside the through hole 216a becomes large, and the liquid water before reaching the power generation cell 1 easily flows into the gas discharge channels PA3 and PA6.

[0076] (4) In the third liquid water inflow suppression part 53, the through holes 211 of the frame 21 are larger than the through holes 211a of the dummy frame 210 (FIGS. 9A, 9B). Thereby, the liquid water flowing into the gas supply channels PA1 and PA4 is blocked at the edge 217a of the through hole 211a of the dummy frame 210, and it is possible to suppress the liquid water from flowing into the channels PA1 and PA4 beyond the through hole 211.

[0077] (5) The gas supply through holes 102a and 102d (gas supply ports) of the end unit 102 are provided with a downwardly inclined surface 102g whose opening area gradually increases in the gas flow direction (FIG. 10). Thereby, since the liquid water flows obliquely downward along the inclined surface 102g, the flow of the liquid water to the front dummy cell 10 is promoted, and the liquid water can be efficiently guided to the exhaust gas channels PA3 and PA6 through the dummy cell 10.

[0078] (6) The stacking direction of the fuel cell stack 100 is substantially horizontal (front-rear direction) (FIG. 1). The vertical position of the lower end of the through hole 211 of the frame 21 and the vertical position of the through hole 211a of the dummy frame 210 are different from each other (FIGS. 7A, 7B, 8, 9A, 9B). Thereby, the reaction gas hits the edge 217 of the frame 21 of the rear end power generation cell 1a or the edge 217a of the dummy frame 210 of the dummy cell 10, and the liquid water contained in the reaction gas can be separated well.

[0079] (7) One edge 217, 217a of the through hole 211 of the frame 21 and the through hole 211a of the dummy frame 210 has a protruding portion that protrudes into the other opening region of the through hole 211 and the through hole 211a when the through holes 211, 211a are viewed along the front-rear direction (FIGS. 7B, 9B). Thereby, a part of the reaction gas flowing into the gas supply channels PA1, PA4 hits the protruding portions (edges 217, 217a) before reaching the power generation cell 1, and the flow of liquid water to the power generation cell 1 can be suppressed.

[0080] (8) The fuel cell stack 100 has lower protruding portions 218, 218a provided at one lower end edge of the through hole 211 and the through hole 211a as a part of the protruding portions (FIGS. 7B, 9B). Thereby, the liquid water flowing through the gas supply channels PA1, PA4 can be blocked well.

[0081] The above-described embodiment can be modified into various forms. Hereinafter, several modification examples will be described. In the above-described embodiment, the through-hole 211a (second communication hole) of the dummy frame 210 in the gas supply flow paths PA1 and PA4 is made larger or smaller in the vertical direction than the through-hole 211 (first communication hole) of the frame 21. However, the shapes of the through-holes 211 and 211a may be made different from each other while keeping the sizes (opening areas) the same. While keeping the sizes and shapes the same, the positions of the axes CL1 and CL2 of the through-holes 211 and 211a may be made different from each other. That is, as long as the extended surface obtained by extending the opening surface of the second communication hole toward the first communication hole does not coincide with the opening surface of the first communication hole, the configurations of the first communication hole and the second communication hole are not limited to those described above.

[0082] In the above-described embodiment (FIG. 8), the through-hole 216a (fourth communication hole) of the dummy frame 210 in the gas discharge flow paths PA3 and PA6 is made smaller than the through-hole 216 (third communication hole) of the frame 21. However, as long as the pressure in region B is configured to be reduced, the configurations of the third through-hole and the fourth through-hole are not limited to those described above. In the above-described embodiment, the through-holes 211 and 211a of the frame 21 and the dummy frame 210 are made smaller than the through-hole 301 of the separator 3 and the dummy separator 12. The through-hole 211 of the frame 21 is configured as the first communication hole of the power generation cell 1, and the through-hole 211a of the dummy frame 210 is configured as the second communication hole of the dummy cell 10. In this regard, the through-holes of the separator 3 and the dummy separator 12 may be made smaller than the through-holes of the frame 21 and the dummy frame 210, and the through-hole of the separator 3 may be configured as the first communication hole, and the through-hole of the dummy separator 12 may be configured as the second communication hole.

[0083] In the above embodiment, the cell stack 101 is configured by stacking a plurality of cells in the front-rear direction. However, a cell stack may be configured by stacking a plurality of cells in a predetermined direction other than the front-rear direction. In this case, the stacking direction is preferably a substantially horizontal direction. In the above embodiment, the dummy separator 12 adjacent to the end unit 102 is configured by a joined body of the front plate 3F and the rear plate 3R, similar to the separator 3. However, it may be configured by a single plate (for example, the front plate 3F), and the configuration of the dummy cell 10 is not limited to that described above. In the above embodiment, the through holes 211 and 211a of the gas supply passage PA1 for fuel gas are configured in a substantially rectangular shape, but may be configured to be convex downward.

[0084] The above description is merely an example, and the present invention is not limited to the above-described embodiment and modification examples as long as the features of the present invention are not impaired. It is also possible to arbitrarily combine one or more of the above embodiment and modification examples, and it is also possible to combine the modification examples with each other.

Description of Reference Numerals

[0085] 1 Power generation cell, 1a Rear-end power generation cell, 10 Dummy cell, 21 Frame, 100 Fuel cell stack, 101 Cell stack, 102 End unit, 102a, 102c, 102d, 102f Through hole, 102g Inclined surface, 210 Dummy frame, 211, 211a Through hole, 211b Extension surface, 217, 217a Edge, 218, 218a Lower protruding portion, PA1, PA4 Gas supply passage, PA3, PA6 Gas discharge passage, PAa Anode passage, PAc Cathode passage

Claims

1. A plurality of power generation cells which are power generation bodies laminated in a predetermined direction, and a dummy cell which is a non-power generation body arranged adjacent to an end power generation cell located at one end in the predetermined direction among the plurality of power generation cells, having a gas supply flow path to which a reaction gas is supplied and a gas discharge flow path from which the reaction gas is discharged, each extending along the predetermined direction, and a cell stack provided with a gas flow path communicating the gas supply flow path and the gas discharge flow path; An end unit arranged adjacent to the dummy cell and provided with a gas supply port communicating with the gas supply flow path and a gas discharge port communicating with the gas discharge flow path; A first communication hole constituting the gas supply flow path is opened in the end power generation cell; A second communication hole constituting the gas supply flow path is opened in the dummy cell; The fuel cell stack is characterized in that the first communication hole and the second communication hole are provided such that an extended surface obtained by extending the opening surface of the second communication hole in the predetermined direction toward the first communication hole does not coincide with the opening surface of the first communication hole.

2. In the fuel cell stack according to Claim 1, The fuel cell stack is characterized in that the first communication hole is smaller than the second communication hole.

3. In the fuel cell stack according to Claim 2, A third communication hole constituting the gas discharge flow path is opened in the end power generation cell; The fuel cell stack is characterized in that a fourth communication hole which is smaller than the third communication hole and constitutes the gas discharge flow path is opened in the dummy cell.

4. In the fuel cell stack according to Claim 1, The fuel cell stack is characterized in that the first communication hole is larger than the second communication hole.

5. In the fuel cell stack according to any one of Claims 1 to 4, The fuel cell stack is characterized in that the gas supply port is provided with an inclined surface having a downward gradient such that the opening area gradually increases in the gas flow direction.

6. In the fuel cell stack according to any one of Claims 1 to 4, The predetermined direction is a substantially horizontal direction, The fuel cell stack is characterized in that the vertical position of the lower end of the first communication hole and the vertical position of the lower end of the second communication hole are different from each other.

7. In the fuel cell stack according to any one of Claims 1 to 4, One edge of the first communication hole and the second communication hole has a protruding portion that protrudes into the other opening region of the first communication hole and the second communication hole when the first communication hole and the second communication hole are viewed along the predetermined direction. A fuel cell stack characterized by that.

8. In the fuel cell stack according to claim 7, The predetermined direction is a substantially horizontal direction, The fuel cell stack is characterized in that the protruding portion is provided at an edge of one lower end of the first communication hole and the second communication hole.

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