JP7709997B2 - Fuel Cell Stack - Google Patents

Description

The present invention relates to a fuel cell stack.

In recent years, technological developments have been made on fuel cells that contribute to energy efficiency, so that more people can have access to affordable, reliable, sustainable and advanced energy. As a fuel cell stack used in this type of fuel cell, a technology has been known in which a honeycomb member is placed at the inlet of a gas supply manifold into which the reactant gas flows, and the honeycomb member rectifies the gas flow, in order to supply the reactant gas evenly to multiple power generation cells (see, for example, Patent Document 1).

JP 2006-147456 A

However, even if the reactant gas is rectified and introduced into the gas supply manifold as described in Patent Document 1, there is a tendency for the amount of reactant gas supplied to the power generation cell to differ between the side closer to the inlet of the gas supply manifold and the side farther away, which in turn tends to result in a difference in the amount of power generation.

A fuel cell stack according to one aspect of the present invention includes a cell stack formed by stacking a plurality of power generation cells having an electrolyte membrane in a first direction, and an end unit disposed adjacent to the cell stack, the end unit being provided with a gas inlet channel and a gas outlet channel penetrating the end unit in the first direction on one side and the other side in a second direction perpendicular to the first direction, through which a reactant gas flows in and out, respectively, and the cell stack being provided with a gas supply channel and a gas exhaust channel penetrating the cell stack in the first direction on one side and the other side in the second direction across the electrolyte membrane, the gas inlet channel being arranged such that an axis passing through the center of the gas inlet channel is aligned in the same line as an axis passing through the center of the gas supply channel at an inlet of the gas inlet channel and faces one side in the second direction at an outlet of the gas inlet channel.

The present invention makes it possible to reduce variation in the amount of power generated among multiple power generating cells.

1 is a perspective view showing a schematic overall configuration of a fuel cell stack according to an embodiment of the present invention; FIG. 2 is a perspective view showing a schematic configuration of an electrode assembly included in the fuel cell stack of FIG. 1 . FIG. 2 is a diagram illustrating a flow of reactant gas in the fuel cell stack of FIG. 1 . 5 is a diagram showing the relationship between cell number and static pressure in a fuel gas supply flow path and a fuel gas discharge flow path. FIG. FIG. 4 is a diagram showing the relationship between the cell number and the flow rate of fuel gas guided to a power generating cell. 1 is a cross-sectional view showing a configuration of a main part of a fuel cell stack according to an embodiment of the present invention; 6 is a diagram showing the relationship between the cell number obtained by the fuel cell stack of FIG. 5 and the flow rate of fuel gas guided to a power generating cell. FIG. 6 is a diagram showing a modification of FIG. 5 . FIG. 8 is a view taken along line VIII of FIG. FIG. 8 is a diagram showing a modification of FIG. 7 .

Below, an embodiment of the present invention will be described with reference to Figures 1 to 9. A fuel cell stack according to an embodiment of the present invention constitutes a main element of a fuel cell. The fuel cell can be mounted, for example, in a vehicle and generate power to drive the vehicle. Fuel cells can also be mounted in moving objects other than vehicles, such as aircraft and ships, robots, and various industrial machines. First, the overall configuration of a fuel cell stack will be described in brief.

Figure 1 is a perspective view showing the overall configuration of a fuel cell stack 100 according to an embodiment of the present invention. For convenience, the three mutually orthogonal axial directions shown in the figure are defined below as the front-rear direction, the left-right direction, and the up-down direction, and the configuration of each part is described according to these definitions. These directions are not necessarily the same as the front-rear direction, the left-right direction, and the up-down direction of a vehicle. For example, the front-rear direction in Figure 1 may be the front-rear direction, the left-right direction, or the up-down direction of a vehicle.

As shown in FIG. 1, the fuel cell stack 100 has a cell stack 101 formed by stacking a number of power generation cells 1 in the front-rear direction, and end units 102 arranged at both the front and rear ends of the cell stack 101, and has an approximately rectangular parallelepiped shape as a whole. The length of the cell stack 101 in the left-right direction is longer than its length in the up-down direction. For convenience, FIG. 1 shows a single power generation cell 1. The power generation cell 1 has an electrode assembly 2 having an assembly including an electrolyte membrane and an electrode, and separators 3, 3 arranged on both the front and rear sides of the electrode assembly 2 and sandwiching the electrode assembly 2. The electrode assemblies 2 and the separators 3 are arranged alternately in the front-rear direction.

The separator 3 has a pair of front and rear thin metal plates with a corrugated cross section, and is integrally formed by joining the outer peripheries of these thin plates. The separator 3 is made of a conductive material with excellent corrosion resistance, such as titanium, titanium alloy, or stainless steel. A cooling flow path through which a cooling medium flows is formed inside the separator 3, and the power generation surface of the power generation cell 1 is cooled by the flow of the cooling medium. Water, for example, can be used as the cooling medium. The surface (front and rear surfaces) of the separator 3 facing the electrode assembly 2 is made uneven by press molding or the like so as to form a gas flow path between the electrode assembly 2 and the joined body.

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 electrode assembly 2 assembly. 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 oxidizer gas flows is formed between the cathode separator 3 and the electrode assembly 2 assembly. For example, hydrogen gas can be used as the fuel gas, and for example, air can be used as the oxidizer gas. Sometimes, the fuel gas and the oxidizer gas are referred to as reactant gases without distinguishing between them.

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 assembly 20 and a frame 21 that supports the assembly 20. The assembly 20 is a membrane electrode assembly (also known as 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.

The electrolyte membrane is, for example, a solid polymer electrolyte membrane, and a thin film of perfluorosulfonic acid containing water can be used. It is not limited to fluorine-based electrolytes, and hydrocarbon-based electrolytes can also be used.

The anode electrode is an electrode catalyst layer formed on the front surface of the electrolyte membrane and serves as the reaction field for the electrode reaction. A gas diffusion layer is provided on the front surface of the electrode catalyst layer to diffuse and supply the reactant gas. The cathode electrode is an electrode catalyst layer formed on the rear surface of the electrolyte membrane and serves as the reaction field for the electrode reaction. A gas diffusion layer is provided on the rear surface of the electrode catalyst layer to diffuse and supply the reactant gas. The electrode catalyst layer includes a catalyst metal that promotes the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidant gas, an electrolyte with proton conductivity, and carbon particles with electron conductivity. The gas diffusion layer is composed of a conductive material with gas permeability, such as a carbon porous body.

At the anode electrode, the fuel gas (hydrogen) supplied through the anode flow path and gas diffusion layer is ionized by the action of a catalyst and passes through the electrolyte membrane to move to the cathode electrode. The electrons generated at this time pass through an external circuit and are extracted as electrical energy. At the cathode electrode, the oxidant gas (oxygen) supplied through the cathode flow path and gas diffusion layer reacts with the hydrogen ions guided from the anode electrode and the electrons that have moved from the anode electrode to generate water. The generated water provides an appropriate humidity to the electrolyte membrane, and excess water is discharged outside the electrode assembly 2.

The frame 21 is a thin plate having a generally rectangular shape and is made of insulating resin, rubber, or the like. A generally rectangular opening 21a is provided in the center of the frame 21, and a joint 20 is provided to cover the entire opening 21a. On the left side of the opening 21a of the frame 21, three through holes 211-213 that penetrate the frame 21 in the front-to-rear direction are opened in a line up in the vertical direction, and on the right side of the opening 21a, three through holes 214-216 that penetrate the frame 21 in the front-to-rear direction are opened in a line up in the vertical direction.

As shown in FIG. 1, the separators 3 at the front and rear of the electrode assembly 2 are provided with through holes 311-316 that penetrate the separators 3 in the front-rear direction at positions corresponding to the through holes 211-216 in the frame 21. The through holes 311-316 are connected to the through holes 211-216 in the frame 21, respectively. The collection of the through holes 211-216 and 311-316 that communicate with each other forms flow paths PA1-PA6 (indicated by arrows for convenience) that penetrate the cell stack 101 and extend in the front-rear direction. The flow paths PA1-PA6 are sometimes called manifolds. The flow paths PA1-PA6 are connected to a manifold external to the fuel cell stack 100.

The flow path PA1 (solid arrow) extending forward through the through holes 211, 311 is a fuel gas supply flow path. The flow path PA6 (solid arrow) extending rearward through the through holes 216, 316 is a fuel gas exhaust flow path. The fuel gas supply flow path PA1 and the fuel gas exhaust flow path PA6 are connected to the anode flow path facing the front surface of the assembly 20, and as shown by the solid arrow, the fuel gas flows left and right through the anode flow path via the fuel gas supply flow path PA1 and the fuel gas exhaust flow path PA6. The communication between the anode flow path and the other flow paths PA2 to PA5 is blocked via a seal portion (not shown). The fuel gas flowing through the fuel gas exhaust flow path PA6 is the fuel gas after a portion of it has been used at the anode electrode, and is sometimes called fuel exhaust gas.

The flow path PA4 (dotted arrow) extending forward through the through holes 214, 314 is an oxidant gas supply flow path. The flow path PA3 (dotted arrow) extending rearward through the through holes 213, 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 the cathode flow path facing the rear surface of the assembly 20, and as shown by the dotted arrow, the oxidant gas flows in the left-right direction through the cathode flow path via the oxidant gas supply flow path PA4 and the oxidant gas discharge flow path PA3. 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 portion of it has been used at the cathode electrode, and this may be called oxidant exhaust gas. The fuel exhaust gas and the oxidant exhaust gas may also be called reaction exhaust gas without distinguishing between them.

The flow path PA5 (dotted arrow) extending forward through the through holes 215, 315 is a cooling medium supply flow path. The flow path PA2 (dotted arrow) extending rearward through the through holes 212, 312 is a cooling medium discharge flow path. The cooling medium supply flow path PA5 and the cooling medium discharge flow path PA2 are connected to the cooling flow path inside the separator 3, and 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, PA6 is blocked via a seal portion not shown.

The end units 102 arranged 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. The front end unit 102 is sometimes called the dry side end unit, and the rear end unit 102 is sometimes called the wet side end unit. The pair of front and rear terminal plates 4, 4 are arranged on both the front and rear sides of the cell stack 101, sandwiching them. The pair of front and rear insulating plates 5, 5 are arranged on both the front and rear sides of the terminal plate 4, 4. The pair of front and rear end plates 6, 6 are arranged on both the front and rear sides of the insulating plate 5, 5, sandwiching it.

The terminal plate 4 is a metal, substantially rectangular plate-like member, 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 non-conductive, substantially rectangular plate-like member made of resin or rubber, and electrically insulates the terminal plate 4 from the end plate 6. The end plate 6 is a metal or high-strength resin plate-like member, and a connecting member elongated in the front-rear direction that connects the front and rear end plates 6, 6 is fixed to the end plate 6 by a bolt, for example. The fuel cell stack 100 is held in a state in which it is pressed in the front-rear direction by the end plates 6, 6 via the connecting member. A case (not shown) that surrounds the cell stack 101 may be used as a connecting member, and the end plates 6, 6 may be fixed to the front and rear end faces of the case, respectively.

The rear end unit 102 has a number of through holes 102a-102f that penetrate the end unit 102 in the front-rear direction. Note that the through holes 102a-102f include a through hole that penetrates the terminal plate 4, a through hole that penetrates the insulating plate 5, and a through hole that penetrates the end plate 6, but for convenience, in FIG. 1, these are collectively shown as through holes 102a-102f.

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

More specifically, a fuel gas tank storing high-pressure fuel gas is connected to the through hole 102a via an ejector, injector, etc., and the fuel gas in the fuel gas tank is supplied to the fuel cell stack 100 via the through hole 102a (fuel gas inlet passage 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 outlet passage 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 again to the fuel cell stack 100. The separated water is discharged to the outside through the drain passage.

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 inlet passage PA14). The oxidant gas (oxidant exhaust gas) flows out from the through-hole 102c (oxidant gas outlet passage PA13).

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 via the through-hole 102e (cooling medium inlet passage PA15). The cooling medium is discharged from the through-hole 102b (cooling medium outlet passage PA12). The discharged cooling medium is cooled by heat exchange in the radiator and is supplied again to the fuel cell stack 100 via the through-hole 102e.

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

Figure 3 is a diagram showing a schematic diagram of the flow of reactant gas (fuel gas as an example). Note that the flow of oxidant gas is in the opposite left-right direction to that shown in Figure 3. In the following, the number of stacked power generating cells 1 included in the cell stack 101 is N, and each power generating cell 1 is assigned a cell number n from 1 to N for explanation. The rear end power generating cell 1 is the first cell 1_1, and the front end power generating cell is the Nth cell 1_N. The left-right center line CL0 of the cell stack 101 is the center of the region (power generating region) AR1 where the assembly 20 (Figure 2) is provided and power generation is performed.

As shown in FIG. 3, the cell stack 101 is provided with a fuel gas supply flow path PA1 on the left side of the power generation area AR1, and a fuel gas exhaust flow path PA6 on the right side. In addition, the end unit 102 at the rear of the cell stack 101 is provided with a fuel gas inlet path PA11 on the left side that communicates with the fuel gas supply flow path PA1, and a fuel gas outlet path PA16 on the right side that communicates with the fuel gas exhaust flow path PA6. FIG. 3 shows an axis CL1 passing through the center of the fuel gas supply flow path PA1 and an axis CL11 passing through the center of the fuel gas inlet path PA11.

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

The flow rate of the fuel gas is faster nearer the inlet of the fuel gas supply flow passage PA1 and slower farther from the inlet. For this reason, as shown in FIG. 4A, the static pressure P is smaller nearer the inlet of the fuel gas supply flow passage PA1 and larger farther from the inlet. In this case, the static pressure difference between the flow passages PA1 and PA6 is larger nearer the inlet of the fuel gas supply flow passage PA1. For this reason, with regard to the relationship between the cell number n and the flow rate of the fuel gas (gas flow rate G) introduced to the power generation cell 1, as shown by characteristic f3 in FIG. 4B, the gas flow rate G is maximum for the first cell 1_1 and minimum for the Nth cell 1_N.

Here, if the gas flow rate G required to obtain the required amount of power generation is defined as the required gas flow rate G1, then in characteristic f3, when the cell number n is equal to or greater than a predetermined number, the gas flow rate G falls below the required gas flow rate G1. As a result, there is a risk of unstable power generation. In addition, water may accumulate upstream of the fuel gas supply flow path PA1 due to condensation in the piping, and the accumulated water flows into the fuel gas supply flow path PA1 along with the flow of fuel gas. In this case, the closer the power generation cell 1 is to the inlet of the fuel gas supply flow path PA1, i.e., the smaller the cell number n, the more likely water is to penetrate, and there is a risk of unstable power generation due to the intrusion of excessive water.

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

Figure 5 is a cross-sectional view showing the main configuration of the fuel cell stack 100 according to this embodiment, and mainly shows the configuration of the fuel gas inlet channel PA11. Although not shown, if Figure 5 is moved symmetrically (line symmetrically) about the center line CL0, it becomes the configuration of the oxidant gas inlet channel PA14. As shown in Figure 5, the terminal plate 4, insulating plate 5, and end plate 6 that make up the rear end unit 102 are each provided with through holes 41, 51, and 61 that penetrate these plates 4 to 6 in the front-rear direction.

The insulating plate 5 is provided with a protruding portion 50 that protrudes rearward beyond the front end surface of the end plate 6. The rear end surface 5a of the protruding portion 50 and the rear end surface 6a of the end plate 6 are located on approximately the same plane. The protruding portion 50 has an approximately cylindrical shape as a whole, and a through hole 61 of the end plate 6 is fitted into the outer circumferential 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 through holes 41, 51 form the fuel gas inlet passage PA11. However, since the plate thickness of the terminal plate 4 is thin, the passage PA11 is mainly formed by the through hole 51 of the insulating plate 5. The through hole 41 of the terminal plate 4 is circular with the axis CL1 as its center.

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

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 and are also equal to the diameter of the through hole 41 of the terminal plate . Therefore, the cross-sectional area of the fuel gas inlet channel PA11 is constant over the entire length.

The axis CL11 of the rear through hole 511 extends approximately 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, but is offset a certain amount to the right from the axis CL1. Therefore, the front through hole 512 extends obliquely so as to connect the rear through hole 511 and the through hole 41 of the terminal plate 4. In other words, when viewed along the flow direction of the fuel gas, the axis CL12 of the front through hole 512 extends obliquely toward the left and outside of the center line CL0 of the cell stack 101.

In this embodiment, the outlet side of the fuel gas inlet passage PA11 is formed at an angle toward the opposite side (left side) of the center line CL0. Therefore, the fuel gas that passes through the fuel gas inlet passage PA11 has a velocity component in the opposite direction of the power generation area AR1 (away from the power generation area 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, i.e., the smaller the cell number n, the more difficult it is for the fuel gas to flow into the power generation area AR1 on the right. As a result, more fuel gas flows into the power generation cell 1 that is farther from the inlet of the fuel gas supply flow path PA1.

As a result, as shown by characteristic f4 (dotted line) in Figure 6, the variation in the gas flow rate G for each power generation cell 1 is suppressed, and the gas flow rate G for all power generation cells 1 is equal to or greater than the predetermined required gas flow rate G1. This makes it possible to suppress the occurrence of unstable power generation, and to obtain good power generation performance for the fuel cell stack 100.

In addition, if water infiltrates the fuel gas supply flow path PA1 through the fuel gas inlet channel PA11, the water is sprayed to the opposite side (left side) of the power generation area AR1. This makes it difficult for water to infiltrate the power generation cells 1 on the inlet side of the flow path PA1, and water infiltrates evenly into each power generation cell 1. As a result, excessive water infiltration into the power generation cells 1 can be prevented, and the occurrence of unstable power generation due to water infiltration can also be suppressed. The above effects are similar for the oxidant gas supply flow path PA4.

Figure 7 is a modified example of Figure 5. In the example of Figure 7, the through hole 51 of the insulating plate 5 is also divided into a rear through hole 511 and a front through hole 512 at the bent portion 52. However, the rear through hole 511 is not offset with respect to the fuel gas supply flow passage PA1, and the axis CL11 is located on the same line as the axis CL1. Meanwhile, a protrusion 53 that protrudes to the left is provided on the front end surface 5b of the insulating plate 5. The protrusion 53 extends at an angle from the bent portion 52 to the front end surface 5b. Therefore, the axis CL12 that passes through the center of the front through hole 512 also extends at an angle.

As shown in FIG. 8, which is a view taken along the arrow VIII in FIG. 7, the edge of the front through hole 512 (the left end of the protrusion 53) on the front end surface 5b of the insulating plate 5 extends in the vertical direction. As a result, the axis CL12 of the front through hole 512 is located to the left of the axis CL1 on the front end surface 5b of the insulating plate 5.

As a result, the fuel gas that has passed through the fuel gas inlet passage PA11 flows diagonally toward the opposite side (left side) of the power generation area AR1. Therefore, as in FIG. 5, the closer to the inlet of the fuel gas supply flow passage PA1, the less likely the fuel gas is to flow into the power generation area AR1, and the farther from the inlet, the more likely it is to flow into the power generation area AR1. This reduces the variation in the fuel gas supplied to the power generation cell 1, and suppresses the occurrence of unstable power generation. It also prevents excessive water from entering the power generation cell 1 on the inlet side of the flow passage PA1 from the fuel gas inlet passage PA11, and suppresses the occurrence of unstable power generation due to water intrusion.

According to this embodiment, the following advantageous effects can be obtained.
(1) The fuel cell stack 100 includes a cell stack 101 formed by stacking a plurality of power-generating cells 1, each having an electrolyte membrane, in a front-to-rear direction (first direction), and an end unit 102 disposed adjacent to the cell stack 101 ( FIG. 1 ). The end unit 102 is provided, on the left and right sides, with gas inflow channels (fuel gas inflow channel PA11, oxidant gas inflow channel PA14) and gas outflow channels (fuel gas outflow channel PA16, oxidant gas outflow channel PA113) that penetrate the end unit 102 in the front-to-rear direction and through which reactant gases (fuel gas, oxidant gas) flow in and out ( FIG. 1 ). The cell stack 101 is provided with gas supply channels (fuel gas supply channel PA1, oxidant gas supply channel PA4) and gas discharge channels (fuel gas discharge channel PA6, oxidant gas discharge channel PA3) that penetrate the cell stack 101 in the front-rear direction and communicate with the gas inlet channels PA11, PA14 and the gas outlet channels PA16, PA13, respectively, on the left and right sides of the electrolyte membrane (FIG. 1). The gas inlet channel (e.g., fuel gas inlet channel PA11) is provided such that an axis CL12 passing through the center of the fuel gas inlet channel PA11 faces the left side, which is the opposite side to the power generation area AR1, at the outlet of the fuel gas inlet channel PA11 (FIGS. 5 and 7).

As a result, the fuel gas that has passed through the fuel gas inlet passage PA11 flows diagonally toward the opposite side of the power generation area AR1, so the closer the fuel gas is to the inlet of the fuel gas supply flow passage PA1, the less likely it is to flow into the power generation area AR1, and the farther it is from the inlet, the more likely it is to flow. This reduces the variation in the fuel gas supplied to each power generation cell 1, and suppresses the occurrence of unstable power generation. It also prevents excessive water from entering the power generation cell 1 on the inlet side of the fuel gas supply flow passage PA1, and suppresses the occurrence of unstable power generation due to water intrusion.

(2) The gas inlet passage (e.g., fuel gas inlet passage PA11) is extended obliquely from the outlet of the fuel gas inlet passage PA11 toward the left side, which is the opposite side of the power generation area AR1 (Figure 5). As a result, since the fuel gas inlet passage PA11 has a smooth shape, the fuel gas flows smoothly along the flow path PA11, and the fuel gas can be efficiently guided to the power generation area AR1.

(3) At the outlet of the gas inlet passage (e.g., fuel gas inlet passage PA11), the insulating plate 5 has a protrusion 53 that protrudes to the left side, opposite the power generation area AR1 (FIG. 7). This simplifies the configuration because it is not necessary to offset the axis CL11 of the fuel gas inlet passage PA11 from the axis CL1 of the fuel gas supply passage PA1.

The above embodiment can be modified in various ways. Some modified examples are described below. In the above embodiment (FIG. 7), the insulating plate 5 is provided with a protrusion 53. That is, the insulating plate 5 is configured so that the insulating plate itself has the protrusion 53, but the protrusion may be provided separately from the insulating plate 5. FIG. 9 is a diagram showing an example of this. 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 placed in the recess 54. The plate 55 is sandwiched between the insulating plate 5 and the terminal plate 4, and protrudes from the recess 54 to the left. This makes it difficult for fuel gas to flow to the power generation cell 1 with a small cell number n, thereby suppressing the variation in the amount of power generation. 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.

In the above embodiment (FIG. 5), the axis CL11 is offset from the axis CL1, and the fuel gas inlet passage PA11 is provided on the insulating plate 5 at an angle, that is, in the opposite direction to the center line CL0 of the cell stack 101. Also, in the above embodiment (FIG. 7), a protrusion 53 is provided on the front end of the insulating plate 5 in the opposite direction to the center line CL0. However, as long as the axis passing through the center of the gas inlet passage is provided so as to face the opposite side of the electrolyte membrane at the outlet of the gas inlet passage, the configuration of the gas inlet passage is not limited to the above. The gas inlet passage may be extended at an angle toward the opposite side of the electrolyte membrane at the outlet of the gas inlet passage, and a protrusion may be provided on the opposite side of the electrolyte membrane.

In the above embodiment, the gas inlet passages (fuel gas inlet passage PA11, oxidant gas inlet passage PA14) are formed by the insulating plate 5, but the gas inlet passages may be formed in other places than the insulating plate as long as they are formed in the end unit. In the above embodiment, the cell stack 101 is formed by alternately stacking the electrode assembly 2 and the separator 3 as a membrane electrode assembly including an electrolyte membrane and an electrode in the front-rear direction (first direction), but the first direction is not limited to the front-rear direction and may be the up-down direction. Therefore, one side of the second direction where the gas inlet passages (fuel gas inlet passage PA11, oxidant gas inlet passage PA14) and the gas supply passages (fuel gas supply passage PA1, oxidant gas supply passage PA4) are provided, and the other side of the second direction where the gas outlet passages (fuel gas outlet passage PA16, oxidant gas outlet passage PA13) and the gas exhaust passages (fuel gas exhaust passage PA6, oxidant gas exhaust passage PA3) are provided do not have to be the left or right side.

The above describes an example of mounting a fuel cell having a fuel cell stack 100 on a vehicle, but the fuel cell stack can also be mounted on moving objects other than vehicles, such as aircraft and ships, robots, and various industrial machines.

The above description is merely an example, and the present invention is not limited to the above-mentioned embodiment and modifications, as long as the characteristics of the present invention are not impaired. It is also possible to combine one or more of the above-mentioned embodiment and modifications in any desired manner, and it is also possible to combine modifications together.

1 Power generating cell, 5 Insulating plate, 51 Through hole, 52 Bend, 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 exhaust flow path, PA4 Oxidant gas supply flow path, PA6 Fuel gas exhaust flow path, PA11 Fuel gas inlet path, PA13 Oxidant gas outlet path, PA14 Oxidant gas inlet path, PA16 Fuel gas outlet path

Claims (3)

a cell stack formed by stacking a plurality of power generation cells, each having an electrolyte membrane, in a first direction;
and an end unit disposed adjacent to the cell stack,
the end unit is provided with a gas inlet passage and a gas outlet passage penetrating the end unit in the first direction, through which a reaction gas flows in and flows out, on one side and the other side in a second direction perpendicular to the first direction, and
a gas supply channel and a gas exhaust channel penetrating the cell stack in the first direction and communicating with the gas inlet channel and the gas outlet channel, respectively, are provided on the one side and the other side in the second direction with the electrolyte membrane interposed therebetween,
a gas inlet passage having an axis passing through a center of the gas inlet passage that is collinear with an axis passing through the center of the gas supply passage at an inlet of the gas inlet passage, and that faces toward one side of the second direction at an outlet of the gas inlet passage. 2. The fuel cell stack according to claim 1,
The end unit has a protrusion protruding to the one side in the second direction at an outlet of the gas inlet passage. 3. The fuel cell unit according to claim 2,
The end unit has an insulating plate that forms the gas inlet passage,
2. A fuel cell stack according to claim 1, wherein the protrusion is formed of a plate member provided at an end of the insulating plate so as to protrude to the one side in the second direction.