Fuel cell stack

Abstract

To reduce a variation in an amount of power generated among multiple power generating cells.SOLUTION: A fuel cell stack includes a cell stack 101 configured by stacking a plurality of power generation cells having an electrolyte membrane in a front-rear direction, and an end unit 102 disposed adjacent to the cell stack 101. The end unit 102 is provided with a gas inlet channel PA11 that penetrates the end unit 102 in the front-rear direction and through which reactant gas flows in. The cell stack 101 is provided with a gas supply channel PA1 on a left side across the electrolyte membrane, the gas supply channel PA1 penetrates the cell stack 101 in the front-rear direction and communicates with the gas inlet channel PA11. The gas inlet channel PA11 is provided such that an axis CL12 passing through a center of the gas inlet channel PA11 faces left at an outlet of the gas inlet channel PA11.SELECTED DRAWING: Figure 5

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 fuel cell stack used in this type of fuel cell, conventionally, for the purpose of uniformly supplying reaction gas to a plurality of power generation cells, a honeycomb member has been disposed at the inlet of a gas supply manifold into which the reaction gas flows, and a technique has been known in which the gas is rectified by the honeycomb member (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, as described in Patent Document 1 above, even if the reaction gas is rectified and led to the gas supply manifold, a difference is likely to occur in the supply amount of the reaction gas to the power generation cells between the side close to the inlet of the gas supply manifold and the side far from it, and for this reason, a difference is also likely to occur in the power generation amount.

Means for Solving the Problems

[0005] A fuel cell stack according to one aspect of the present invention includes a cell stack body configured by laminating a plurality of power generation cells having an electrolyte membrane in a first direction, and an end unit disposed adjacent to the cell stack body. The end unit is provided with a gas inlet passage and a gas outlet passage through which reaction gas flows in and out, respectively, penetrating the end unit in the first direction, on one side and the other side in a second direction orthogonal to the first direction. The cell stack body is provided with a gas supply passage and a gas discharge passage that penetrate the cell stack body in the first direction and communicate with the gas inlet passage and the gas outlet passage, respectively, with the electrolyte membrane interposed therebetween, on one side and the other side in the second direction. The gas inlet passage is such that the axis passing through the center of the gas inlet passage is At the inlet of the gas inflow path, it is located on the same straight line as the axis passing through the center of the gas supply path, provided at the outlet of the gas inlet passage so as to face one side in the second direction.

Advantages of the Invention

[0006] According to the present invention, variations in the power generation amount among a plurality of power generation cells can be suppressed.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 9. The fuel cell stack according to the embodiment of the present invention constitutes the main elements of the fuel cell. The fuel cell can be mounted on, for example, a vehicle and generate electric power for driving the vehicle. The fuel cell can also be mounted on moving bodies other than vehicles such as aircraft and ships, robots, and various industrial machines. 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 an embodiment of the present invention. 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. These directions are not necessarily the same as the front-rear direction, the left-right direction, and the up-down direction of the vehicle. For example, the front-rear direction in FIG. 1 may be the front-rear direction of the vehicle, the left-right direction, or the up-down direction.

[0010] As shown in FIG. 1, the fuel cell stack 100 has a cell stack 101 formed by stacking a plurality of power generation cells 1 in the front-rear direction, and end units 102 arranged at both front and rear ends of the cell stack 101, and the whole exhibits a substantially rectangular parallelepiped shape. The length of the cell stack 101 in the left-right direction is longer than the length in the up-down direction. For convenience, a single power generation cell 1 is shown in FIG. 1. The power generation cell 1 has an electrode assembly 2 having a joined body including an electrolyte membrane and an electrode, and separators 3, 3 arranged 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.

[0011] The separator 3 has a pair of front and rear thin metal plates with a corrugated cross-section, and the outer peripheries of these thin plates are joined together to form an integral structure. A conductive material with excellent corrosion resistance is used for the separator 3, and for example, titanium, titanium alloy, stainless steel, etc. can be used. Inside the separator 3, a cooling flow path through which a cooling medium flows is formed, and the power generation surface of the power generation cell 1 is cooled by the flow of the cooling medium. For example, water can be used as the cooling medium. The surfaces (front and rear surfaces) 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 joined body of the electrode assembly 2.

[0012] The separator 3 on the front side of the electrode assembly 2 is, for example, an anode-side separator (anode separator), and an anode flow path through which fuel gas flows is formed between the anode separator 3 and the joined body of the electrode assembly 2. The separator 3 on the rear side of the electrode assembly 2 is, for example, a cathode-side separator (cathode separator), and a cathode flow path through which oxidant gas flows is formed between the cathode separator 3 and the joined body of the electrode assembly 2. For example, hydrogen gas can be used as the fuel gas, and air can be used as the oxidant gas. Sometimes, these are collectively referred to as reaction gases without distinguishing between the fuel gas and the oxidant gas.

[0013] Figure 2 is a perspective view showing the schematic configuration of the electrode assembly 2. As shown in Figure 2, 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 (so-called MEA; Membrane Electrode Assembly), and has an electrolyte membrane, an anode electrode provided on the front surface of the electrolyte membrane, and a cathode electrode provided on the rear surface of the electrolyte membrane.

[0014] The electrolyte membrane is, for example, a solid polymer electrolyte membrane, and a thin film of perfluorosulfonic acid containing moisture can be used. Not limited to fluorine-based electrolytes, hydrocarbon-based electrolytes can also be used.

[0015] The anode electrode is an electrode catalyst layer formed on the front surface of the electrolyte membrane and serving as a reaction field for the electrode reaction. A gas diffusion layer for diffusing and supplying the reaction gas is provided on the front surface of the electrode catalyst layer. The cathode electrode is an electrode catalyst layer formed on the rear surface of the electrolyte membrane and serving as a reaction field for the electrode reaction. A gas diffusion layer for diffusing and supplying the reaction gas is provided on the rear surface of the electrode catalyst layer. The electrode catalyst layer contains a catalyst metal that promotes the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidant gas, an electrolyte having proton conductivity, carbon particles having electron conductivity, and the like. The gas diffusion layer is composed of a conductive member having gas permeability, such as a carbon porous body.

[0016] In the anode electrode, the fuel gas (hydrogen) supplied through the anode flow path and the gas diffusion layer is ionized by the action of the catalyst, passes through the electrolyte membrane, 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, the oxidant gas (oxygen) supplied through the cathode flow path and the gas diffusion layer reacts with the hydrogen ions guided from the anode electrode and the electrons moved from the anode electrode, and water is generated. The generated water gives appropriate humidity to the electrolyte membrane, and the excess water is discharged to the outside of the electrode assembly 2.

[0017] The frame 21 is a thin plate having a substantially rectangular shape and is composed of an insulating resin, rubber, or the like. A substantially rectangular opening 21a is provided in the central portion of the frame 21, and the joined body 20 is provided so as to cover the entire opening 21a. 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, and on the right side of the opening 21a of the frame 21, three through holes 214 to 216 penetrating the frame 21 in the front-rear direction are opened side by side in the vertical direction.

[0018] As shown in FIG. 1, in the separators 3 before and after the electrode assembly 2, through holes 311 to 316 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. The through holes 311 to 316 communicate with the through holes 211 to 216 of the frame 21 respectively. By the set of these mutually communicating through holes 211 to 216 and 311 to 316, 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.

[0019] The flow path PA1 (solid line arrow) extending forward through the through holes 211 and 311 is a fuel gas supply flow path. The flow path PA6 (solid line arrow) extending rearward through the through holes 216 and 316 is a fuel gas discharge flow path. The fuel gas supply flow path PA1 and the fuel gas discharge flow path PA6 communicate with the anode flow path facing the front surface of the joined body 20, and as shown by the solid line arrow, fuel gas flows in the anode flow path in the left-right direction through the fuel gas supply flow path PA1 and the fuel gas discharge flow path PA6. The communication between the anode flow path and the other flow paths PA2 to PA5 is blocked through a seal portion (not shown). The fuel gas flowing through the fuel gas discharge flow path PA6 is the fuel gas after a part of it has been used at the anode electrode, and this may be called fuel exhaust gas.

[0020] The flow path PA4 (dotted arrow) extending forward through the through holes 214 and 314 is an oxidant gas supply flow path. The flow path PA3 (dotted arrow) extending rearward through the through holes 213 and 313 is an oxidant gas discharge flow path. The oxidant gas supply flow path PA4 and the oxidant gas discharge flow path PA3 communicate with a cathode flow path facing the rear surface of the joined body 20. As shown by the dotted arrow, the oxidant gas flows in the left-right direction through the oxidant gas supply flow path PA4 and the oxidant gas discharge flow path PA3 in the cathode flow path. The communication between the cathode flow path and the other flow paths PA1, PA2, PA5, and PA6 is blocked via a seal portion (not shown). The oxidant gas flowing through the oxidant gas discharge flow path PA3 is the oxidant gas after a part of it has been used at the cathode electrode, and this may be referred to as oxidant exhaust gas. Sometimes, without distinguishing between fuel exhaust gas and oxidant exhaust gas, these are collectively referred to as reaction exhaust gas.

[0021] The flow path PA5 (dashed-dotted arrow) extending forward through the through holes 215 and 315 is a cooling medium supply flow path. The flow path PA2 (dashed-dotted arrow) extending rearward through the through holes 212 and 312 is a cooling medium discharge flow path. The cooling medium supply flow path PA5 and the cooling medium discharge flow path PA2 communicate with a cooling flow path inside the separator 3. The cooling medium flows through the cooling flow path via the cooling medium supply flow path PA5 and the cooling medium discharge flow path PA2. The communication between the cooling flow path and the other flow paths PA1, PA3, PA4, and PA6 is blocked via a seal portion (not shown).

[0022] The end units 102 disposed on both the front and rear sides of the cell stack 101 each have a terminal plate 4, an insulating plate 5, and an end plate 6. Note that the front end unit 102 may be referred to as the dry side end unit, and the rear end unit 102 may be referred to as the wet side end unit. A pair of front and rear terminal plates 4, 4 are disposed on both the front and rear sides of the cell stack 101 with the cell stack 101 interposed therebetween. A pair of front and rear insulating plates 5, 5 are disposed on both the front and rear sides of the terminal plates 4, 4 with the terminal plates 4, 4 interposed therebetween. A pair of front and rear end plates 6, 6 are disposed on both the front and rear sides of the insulating plates 5, 5 with the insulating plates 5, 5 interposed therebetween.

[0023] The terminal plate 4 is a substantially rectangular plate-shaped member made of metal and has a terminal portion for extracting the electric power generated by the electrochemical reaction in the cell stack 101. The insulating plate 5 is a substantially rectangular plate-shaped member made of resin or rubber having non-conductivity and electrically insulates the terminal plate 4 and the end plate 6. The end plate 6 is a plate-shaped member made of metal or resin configured with high strength. For example, a longitudinally elongated connecting member for connecting the front and rear end plates 6, 6 to each other is fixed to the end plate 6 with bolts. The fuel cell stack 100 is held in a state of being pressed in the front-rear direction by the end plates 6, 6 via the connecting member. A case (not shown) surrounding the cell stack 101 may be used as the connecting member, and the end plates 6, 6 may be fixed to the front end face and the rear end face of the case, respectively.

[0024] 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. The through holes 102a to 102f each include a through hole penetrating the terminal plate 4, a through hole penetrating the insulating plate 5, and a through hole penetrating the end plate 6. In FIG. 1, for the sake of convenience, these are collectively shown as the through holes 102a to 102f.

[0025] The through hole 102a is opened on the extension line of the fuel gas supply flow path PA1, communicates with the fuel gas supply flow path PA1, and constitutes a fuel gas inflow path PA11. The through hole 102b is opened on the extension line of the cooling medium discharge flow path PA2, communicates with the cooling medium discharge flow path PA2, and constitutes a cooling medium outflow path PA12. The through hole 102c is opened on the extension line of the oxidant gas discharge flow path PA3, communicates with the oxidant gas discharge flow path PA3, and constitutes an oxidant gas outflow path PA13. The through hole 102d is opened on the extension line of the oxidant gas supply flow path PA4, communicates with the oxidant gas supply flow path PA4, and constitutes an oxidant gas inflow path PA14. The through hole 102e is opened on the extension line of the cooling medium supply flow path PA5, communicates with the cooling medium supply flow path PA5, and constitutes a cooling medium inflow path PA15. The through hole 102f is opened on the extension line of the fuel gas discharge flow path PA6, communicates with the fuel gas discharge flow path PA6, and constitutes a fuel gas outflow path PA16.

[0026] More specifically, a fuel gas tank storing high-pressure fuel gas is connected to the through-hole 102a via an ejector, an injector, etc., and the fuel gas in the fuel gas tank is supplied to the fuel cell stack 100 through the through-hole 102a (fuel gas inflow path PA11). A gas-liquid separator is connected to the through-hole 102f, and the fuel gas (fuel exhaust gas) discharged through the through-hole 102f (fuel gas outflow path PA16) is separated into fuel gas and water by the gas-liquid separator. The separated fuel gas is sucked in through the ejector and supplied to the fuel cell stack 100 again. The separated water is discharged to the outside through the drain flow path.

[0027] A compressor for supplying 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 (oxidant gas inflow path PA14). Oxidant gas (oxidant exhaust gas) flows out to the outside from the through-hole 102c (oxidant gas outflow path PA13).

[0028] 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 (cooling medium inflow path PA15). The cooling medium is discharged from the through-hole 102b (cooling medium outflow path PA12). The discharged cooling medium is cooled by heat exchange in the radiator and supplied to the fuel cell stack 100 again through the through-hole 102e.

[0029] The above is the schematic configuration of the fuel cell stack 100. The fuel cell stack 100 is housed in a substantially box-shaped case (not shown) and mounted on a vehicle.

[0030] FIG. 3 is a diagram schematically showing the flow of reaction gas (e.g., fuel gas). Note that the flow of the oxidant gas is opposite to that shown in FIG. 3 in the left - right direction. Hereinafter, the number of stacked power generation cells 1 included in the cell stack 101 is denoted as N, and each power generation cell 1 is assigned a cell number n from 1 to N for explanation. The power generation cell 1 at the rear end is the first cell 1_1, and the power generation cell at the front end is the Nth cell 1_N. The center line CL0 in the left - right direction of the cell stack 101 is the center of the region (power generation region) AR1 where the joining body 20 (FIG. 2) is provided and power generation occurs.

[0031] As shown in FIG. 3, in the cell stack 101, a fuel gas supply channel PA1 is provided on the left side sandwiching the power generation region AR1, and a fuel gas discharge channel PA6 is provided on the right side. Also, in the end unit 102 behind the cell stack 101, a fuel gas inflow channel PA11 communicating with the fuel gas supply channel PA1 is provided on the left side, and a fuel gas outflow channel PA16 communicating with the fuel gas discharge channel PA6 is provided on the right side. In FIG. 3, an axis CL1 passing through the center of the fuel gas supply channel PA1 and an axis CL11 passing through the center of the fuel gas inflow channel PA11 are shown.

[0032] In FIG. 3, the axis CL11 exists on the extension line of the axis CL1, and the axis CL11 coincides with the axis CL1. At this time, the fuel gas flows straight from the fuel gas inflow channel PA11 into the fuel gas supply channel PA1. FIG. 4A is a diagram showing the relationship between the cell number n and the static pressure P in this case. The characteristic f1 in the figure is the static pressure in the fuel gas supply channel PA1, and the characteristic f2 is the static pressure in the fuel gas discharge channel PA6. The difference between the characteristic f1 and the characteristic f2 corresponds to the flow rate of the fuel gas along the power generation cell 1.

[0033] The flow velocity of the fuel gas is faster the closer it is to the inlet of the fuel gas supply passage PA1, and slower the farther it is from the inlet. Therefore, as shown in Fig. 4A, the static pressure P is smaller the closer it is to the inlet of the fuel gas supply passage PA1, and larger the farther it is from the inlet. In this case, the static pressure difference between the passages PA1 and PA6 is larger the closer it is to the inlet of the fuel gas supply passage PA1. For this reason, regarding the relationship between the cell number n and the flow rate of the fuel gas (gas flow rate G) led to the power generation cell 1, as shown in the characteristic f3 of Fig. 4B, the gas flow rate G is maximum at the first cell 1_1 and minimum at the Nth cell 1_N.

[0034] Here, if the gas flow rate G required to obtain the necessary power generation amount is defined as the necessary gas flow rate G1, in the characteristic f3, when the cell number n becomes a predetermined number or more, the gas flow rate G falls below the necessary gas flow rate G1. As a result, there is a risk of causing unstable power generation. Also, upstream of the fuel gas supply passage PA1, water may accumulate due to condensation in the pipe or the like, and the accumulated water flows into the fuel gas supply passage PA1 along the flow of the fuel gas. In this case, the closer the power generation cell 1 is to the inlet of the fuel gas supply passage PA1, that is, the smaller the cell number n of the power generation cell 1, the easier it is for water to infiltrate, and there is a risk of causing unstable power generation due to excessive water infiltration.

[0035] It is necessary to suppress the occurrence of unstable power generation due to such variations in gas flow rate and unstable power generation due to excessive water infiltration. Therefore, in the present embodiment, the gas inflow passages (fuel gas inflow passage PA11, oxidant gas inflow passage PA14) provided in the end unit 102 are configured as follows.

[0036] Fig. 5 is a cross-sectional view showing a main part configuration of the fuel cell stack 100 according to the present embodiment, mainly showing the configuration of the fuel gas inflow passage PA11. Although illustration is omitted, when Fig. 5 is symmetrically (line-symmetrically) moved with respect to the center line CL0, the configuration of the oxidant gas inflow passage PA14 is obtained. As shown in Fig. 5, through holes 41, 51, and 61 that penetrate these plates 4 to 6 in the front-rear direction are respectively formed in the terminal plate 4, the insulating plate 5, and the end plate 6 that constitute the rear end unit 102.

[0037] On the insulating plate 5, a protruding portion 50 that protrudes rearward from the front end surface of the end plate 6 is provided. The rear end surface 5a of the protruding portion 50 and the rear end surface 6a of the end plate 6 are located on substantially the same plane. The protruding portion 50 has an overall substantially cylindrical shape, and the through-hole 61 of the end plate 6 is fitted onto the outer peripheral surface of the protruding portion 50. The front end of the through-hole 51 communicates with the through-hole 41 of the terminal plate 4. Therefore, the fuel gas inflow path PA11 is formed by the through-holes 41 and 51. However, since the plate thickness of the terminal plate 4 is thin, the flow path PA11 is mainly formed by the through-hole 51 of the insulating plate 5. Note that the through-hole 41 of the terminal plate 4 is circular with the axis CL1 as the center.

[0038] Inside the through-hole 51, a bent portion 52 is provided at a position that is a predetermined distance L1 from the rear end surface 5a of the insulating plate 5 and a position that is a predetermined distance L2 from the front end surface 5b. The predetermined distance L1 is the same as or substantially the same as the length of the protruding portion 50, and is shorter than the predetermined distance L2. Note that L1 may be equal to L2, or may be longer than L2.

[0039] The through-hole 51 is composed of a rear through-hole 511 on the rear side of the bent portion 52 and a front through-hole 512 on the front side. The rear through-hole 511 has a circular cross-section centered on an axis CL11 extending in the front-rear direction, and the diameter of the rear through-hole 511 is constant along the axis CL11. The front through-hole 512 has a circular cross-section centered on an axis CL12 extending obliquely in the front-rear direction, and the diameter of the front through-hole 512 is constant along the axis CL12. The diameters of the rear through-hole 511 and the front through-hole 512 are equal to each other, Terminal plate and are also equal to the diameter of the through-hole 41. Therefore, the cross-sectional area of the fuel gas inflow path PA11 is constant over the entire length.

[0040] The axis CL11 of the rear through-hole 511 extends substantially parallel to the axis CL1 of the fuel gas supply flow path PA1. However, the axis CL11 is not on the same line as the axis CL1 and is offset to the right by a predetermined amount from the axis CL1. Therefore, the front through-hole 512 is obliquely extended so as to connect the rear through-hole 511 and the through-hole 41 of the terminal plate 4. That is, when viewed along the flow direction of the fuel gas, the axis CL12 of the front through-hole 512 extends obliquely toward the left outside the center line CL0 of the cell stack 101.

[0041] Thus, in this embodiment, the outlet side of the fuel gas inflow path PA11 is obliquely formed toward the opposite side (left side) of the center line CL0. For this reason, the fuel gas that has passed through the fuel gas inflow path PA11 has a velocity component in the opposite direction (the direction away from the power generation region AR1) of the power generation region AR1 near the inlet of the fuel gas supply flow path PA1. Therefore, the closer to the inlet of the fuel gas supply flow path PA1, that is, the smaller the cell number n, the less likely the fuel gas is to flow into the power generation region AR1 on the right side. As a result, more fuel gas flows into the power generation cell 1 far from the inlet of the fuel gas supply flow path PA1.

[0042] Thereby, as shown by the characteristic f4 (dotted line) in FIG. 6, the variation in the gas flow rate G for each power generation cell 1 is suppressed, and the gas flow rate G in all the power generation cells 1 becomes equal to or greater than a predetermined required gas flow rate G1. For this reason, the occurrence of power generation instability can be suppressed, and good power generation performance of the fuel cell stack 100 can be obtained.

[0043] Also, when water infiltrates into the fuel gas supply flow path PA1 through the fuel gas inflow path PA11, the water is sprayed onto the opposite side (left side) of the power generation region AR1. For this reason, it is difficult for water to infiltrate into the power generation cell 1 on the inlet side of the flow path PA1, and water infiltrates into each power generation cell 1 evenly. As a result, excessive water infiltration into the power generation cell 1 can be prevented, and the occurrence of power generation instability due to water infiltration can also be suppressed. The above functions and effects are the same for the oxidant gas supply flow path PA4.

[0044] FIG. 7 is a modified example of FIG. 5. Also in the example of FIG. 7, the through hole 51 of the insulating plate 5 is divided into a rear through hole 511 and a front through hole 512 with the bent portion 52 as a boundary. However, the rear through hole 511 is not offset with respect to the fuel gas supply flow path PA1, and the axis CL11 is located on the same line as the axis CL1. On the other hand, a protrusion 53 protruding leftward is provided on the front end face 5b of the insulating plate 5. The protrusion 53 extends obliquely from the bent portion 52 to the front end face 5b. For this reason, the axis CL12 passing through the center of the front through hole 512 also extends obliquely.

[0045] Further, as shown in FIG. 8 which is a view VIII in the direction of the arrow in FIG. 7, the edge portion (the left end of the protrusion 53) of the front through hole 512 on the front end face 5b of the insulating plate 5 extends in the vertical direction. Thereby, the axis CL12 of the front through hole 512 is located more to the left of the axis CL1 on the front end face 5b of the insulating plate 5.

[0046] Thereby, the fuel gas that has passed through the fuel gas inflow path PA11 flows obliquely toward the opposite side (left side) of the power generation region AR1. For this reason, similar to FIG. 5, the closer to the inlet of the fuel gas supply flow path PA1, the less likely the fuel gas is to flow into the power generation region AR1, and the farther from the inlet, the easier it is for the fuel gas to flow into the power generation region AR1. For this reason, variations in the fuel gas supplied to the fuel cell 1 can be suppressed, and the occurrence of unstable power generation can be suppressed. Also, it is possible to suppress excessive water from entering the fuel cell 1 on the inlet side of the flow path PA1 from the fuel gas inflow path PA11, and it is also possible to suppress the occurrence of unstable power generation due to the entry of water.

[0047] According to the present embodiment, the following operational effects can be achieved. (1) The fuel cell stack 100 includes a cell stack 101 formed by laminating a plurality of power generation cells 1 having electrolyte membranes in the front-rear direction (first direction), and an end unit 102 disposed adjacent to the cell stack 101 (FIG. 1). In the end unit 102, on the left and right sides, there are provided a gas inflow path (fuel gas inflow path PA11, oxidant gas inflow path PA14) and a gas outflow path (fuel gas outflow path PA16, oxidant gas outflow path PA113) that penetrate the end unit 102 in the front-rear direction and through which reaction gases (fuel gas, oxidant gas) flow in and out (FIG. 1). In the cell stack 101, on the left and right sides with the electrolyte membrane interposed therebetween, there are provided a gas supply path (fuel gas supply flow path PA1, oxidant gas supply flow path PA4) and a gas discharge path (fuel gas discharge flow path PA6, oxidant gas discharge flow path PA3) that penetrate the cell stack 101 in the front-rear direction and communicate with the gas inflow paths PA11, PA14 and the gas outflow paths PA16, PA13, respectively (FIG. 1). The gas inflow path (for example, the fuel gas inflow path PA11) is provided such that the axis CL12 passing through the center of the fuel gas inflow path PA11 faces the left side, which is the opposite side of the power generation region AR1, at the outlet of the fuel gas inflow path PA11 (FIGS. 5 and 7).

[0048] As a result, the fuel gas passing through the fuel gas inflow path PA11 flows obliquely toward the opposite side of the power generation region AR1. Therefore, the closer the fuel gas is to the inlet of the fuel gas supply flow path PA1, the less likely it is to flow into the power generation region AR1, and the farther it is from the inlet, the easier it is to flow. Accordingly, variations in the fuel gas supplied to each power generation cell 1 can be suppressed, and the occurrence of unstable power generation can be inhibited. Also, it is possible to suppress excessive water from entering the power generation cell 1 on the inlet side of the fuel gas supply flow path PA1, and it is possible to suppress the occurrence of unstable power generation due to water ingress.

[0049] (2) The gas inflow path (for example, the fuel gas inflow path PA11) extends obliquely toward the left side, which is the opposite side of the power generation region AR1, at the outlet of the fuel gas inflow path PA11 (FIG. 5). As a result, since the fuel gas inflow path PA11 has a smooth shape, the fuel gas can flow smoothly along the flow path PA11, and the fuel gas can be efficiently guided to the power generation region AR1.

[0050] (3) The insulating plate 5 has a protruding portion 53 that protrudes to the left, which is the opposite side of the power generation region AR1, at the outlet of the gas inflow path (for example, the fuel gas inflow path PA11) (FIG. 7). As a result, it is not necessary to offset the axis CL11 of the fuel gas inflow path PA11 with respect to the axis CL1 of the fuel gas supply path PA1, so the configuration is easy.

[0051] The above-described embodiment can be modified into various forms. Hereinafter, several modification examples will be described. In the above-described embodiment (FIG. 7), the protruding portion 53 is provided on the insulating plate 5. That is, the insulating plate 5 is configured to have the protruding portion 53 itself, but a protruding portion may be provided separately from the insulating plate 5. FIG. 9 is a diagram showing an example thereof. In FIG. 9, a recess 54 is provided on the front end surface 5b of the insulating plate 5 on the right side of the through-hole 51, and a plate 55 is disposed in the recess 54. The plate 55 is sandwiched between the insulating plate 5 and the terminal plate 4 and protrudes leftward from the recess 54. As a result, it becomes difficult for the fuel gas to flow into the power generation cell 1 with a small cell number n, and the variation in the power generation amount can be suppressed. In the configuration of FIG. 9, it is only necessary to process the recess 54 in the insulating plate 5, and the configuration of the insulating plate 5 can be simplified.

[0052] In the above-described embodiment (FIG. 5), the fuel gas inflow path PA11 is provided obliquely with respect to the axis CL1, that is, obliquely in the direction opposite to the center line CL0 of the cell laminate 101, by offsetting the axis CL11 with respect to the axis CL1. Further, in the above-described embodiment (FIG. 7), the protruding portion 53 is provided at the front end portion of the insulating plate 5 in the direction opposite to the center line CL0. However, if the axis passing through the center of the gas inflow path is provided so as to face the opposite side of the electrolyte membrane at the outlet of the gas inflow path, the configuration of the gas inflow path is not limited to the above-described one. The gas inflow path may be extended obliquely so as to face the opposite side of the electrolyte membrane at the outlet of the gas inflow path, and a protruding portion may be provided so as to protrude on the opposite side of the electrolyte membrane.

[0053] In the above-described embodiment, the insulating plate 5 is used to form the gas inflow paths (fuel gas inflow path PA11 and oxidant gas inflow path PA14). However, if it is configured as an end unit, gas inflow paths may be formed by other means than the insulating plate. In the above-described embodiment, the electrode assembly 2 as a membrane electrode assembly including the electrolyte membrane and the electrodes and the separator 3 are alternately laminated in the front-rear direction (first direction) to form the cell stack 101. However, the first direction is not limited to the front-rear direction and may be the up-down direction. Therefore, one side in the second direction where the gas inflow paths (fuel gas inflow path PA11 and oxidant gas inflow path PA14) and the gas supply paths (fuel gas supply flow path PA1 and oxidant gas supply flow path PA4) are provided, and the other side in the second direction where the gas outflow paths (fuel gas outflow path PA16 and oxidant gas outflow path PA13) and the gas discharge paths (fuel gas discharge flow path PA6 and oxidant gas discharge flow path PA3) are provided do not have to be the left side or the right side.

[0054] So far, an example of mounting a fuel cell having the fuel cell stack 100 on a vehicle has been described. However, the fuel cell stack can be mounted on moving bodies other than vehicles such as airplanes and ships, robots, and various industrial machines.

[0055] 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-described embodiment and modification examples, and it is also possible to combine the modification examples with each other.

[0056] 1 power generation cell, 5 insulating plate, 51 through hole, 52 bent portion, 53 protrusion, 100 fuel cell stack, 101 cell stack, 102 end unit, 511 rear through hole, 512 front through hole, CL1,CL12 axis, PA1 fuel gas supply flow path, PA3 oxidant gas discharge flow path, PA4 oxidant gas supply flow path, PA6 fuel gas discharge flow path, PA11 fuel gas inflow path, PA13 oxidant gas outflow path, PA14 oxidant gas inflow path, PA16 fuel gas outflow path

Claims

1. A fuel cell stack comprising a cell stack body configured by laminating a plurality of power generation cells having electrolyte membranes in a first direction, and an end unit disposed adjacent to the cell stack body, wherein in the end unit, a gas inlet passage and a gas outlet passage through which reaction gas flows in and out respectively, penetrating the end unit in the first direction, are provided on one side and the other side in a second direction orthogonal to the first direction, in the cell stack body, a gas supply passage and a gas discharge passage penetrating the cell stack body in the first direction and communicating with the gas inlet passage and the gas outlet passage respectively are provided on one side and the other side in the second direction with the electrolyte membrane therebetween, the gas inlet passage is provided such that an axis passing through the center of the gas inlet passage is located on the same straight line as an axis passing through the center of the gas supply passage at the inlet of the gas inlet passage, and faces the one side in the second direction at the outlet of the gas inlet passage. A fuel cell stack characterized by this.

2. In the fuel cell stack according to Claim 1, the end unit has a protrusion protruding to the one side in the second direction at the outlet of the gas inlet passage. A fuel cell stack characterized by this.

3. In the fuel cell unit according to Claim 2, the end unit has an insulating plate forming the gas inlet passage, the protrusion is constituted by a plate member provided at an end of the insulating plate so as to protrude to the one side in the second direction. A fuel cell stack characterized by this.

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