END PLATE

Abstract

An end plate (4) shaped as a rectangle having a pair of horizontal long sides and a pair of vertical short sides, the end plate (4) being provided at one end in a cell stacking direction of a cell stack (2) in a fuel cell (1) and used to supply a coolant to the cell stack (2) and to discharge the coolant from the cell stack (2). A recess (14) configured to form a flow path in which the coolant flows is open in an opposite surface (12) facing the end in the cell stacking direction of the cell stack (2) and is formed to extend in a horizontal direction along the opposite surface (12). A plurality of ribs (16) are formed on a bottom surface (14a) of the recess (14), and the ribs (16) protrude to an opening position of the recess (14) and are arranged at intervals in a vertical direction.that they extend in the horizontal direction, an inlet portion is provided at one end in the horizontal direction of the recess (14), which allows the coolant to flow from the cell stack (2) into the flow path in the recess (14), an outlet bore (9), which allows the coolant to flow out of the flow path in the recess (14), is provided at another end in the horizontal direction of the recess (14) and at a position higher than the inlet portion, wherein the end plate (4) is characterized in that a pair of upper and lower inner wall surfaces (14b, 14c) in the recess (14) are distributed vertically to the outlet bore (9) in a portion of the recess (14) connected to the inlet portion, and an end close to the inlet portion of a lowermost one of the ribs (16) is closer to the outlet bore (9) than ends close to the inlet portion of the other Ribs (16).,

Description

[0001] The present invention relates to an end plate.

[0002] The document DE 11 2011 105 442 T5 relates to a fuel cell system that prevents condensation in a cell and keeps the system compact. The fuel cell system includes a fuel cell stack with a plurality of stacked cells; a plate-shaped terminal arranged at one end portion of the fuel cell stack in the stacking direction; a stack connector adjacent to the terminal; and an end plate adjacent to the stack connector. The stack connector is arranged between the terminal and the end plate. A groove is formed on a surface of the stack connector. The surface faces the terminal. The groove, the terminal, and the end plate together form a channel for cooling water flowing into the fuel cell stack and circulating out of the fuel cell stack.The channel is formed such that, in a state where the fuel cell system is mounted on a vehicle, the cooling water flows from a rear of the vehicle to a front of the vehicle where a radiator is mounted.

[0003] The document US 2016 / 0 133 953 A1 relates to a fuel cell system. It has a fuel cell including a stacked body in which a plurality of unit cells are stacked; an end plate disposed on one side of at least one of the ends of the stacked body in a stacking direction; and a heat generator. The end plate comprises a first surface including a heat generator contact area defined so that the heat generator contacts the heat generator contact area; and a second surface opposite the first surface, the second surface including a coolant flow path formed into a recessed shape through which a coolant flows, and at least one flow path fin portion provided in the recessed shape of the coolant flow path.

[0004] As disclosed in JP 2016-91845 A, a fuel cell mounted on a vehicle such as an automobile is equipped with an end plate that functions as a manifold to cause a fluid, specifically a fuel gas, an oxidizing gas, and a coolant, to flow through the cell stack of the fuel cell. The fuel cell is cooled by a coolant supplied to and discharged from the cell stack via the end plate, while generating power using the fuel gas and oxidizing gas supplied to and discharged from the cell stack via the end plate.

[0005] The end plate is shaped as a rectangle having a pair of horizontal long sides and a pair of vertical short sides. The end plate has an opposite surface facing one end in the cell stacking direction of the cell stack, a recess opening into the opposite surface and forming a flow path through which the coolant flows. The recess extends in the horizontal direction along the opposite surface. The end plate also has ribs on the bottom surface of the recess. The ribs protrude to the opening position of the recess, are provided at intervals in the vertical direction, and are formed to extend in the horizontal direction.

[0006] The recess has an inlet at one end in the horizontal direction through which a coolant flows in, and an outlet at the other end in the horizontal direction through which the coolant flows out. The outlet is arranged at a position higher than the inlet because the air in the coolant may remain in the flow path in the recess if the outlet is arranged at a position lower than the inlet.

[0007] The opposing surface, the recess, and the ribs in the end plate are covered by a plastic layer. When the end plate is attached to a housing surrounding the cell stack, the portion of the plastic layer covering the opposing surface and the portions of the plastic layer covering the distal end surfaces in the protruding direction of the ribs contact the end in the cell stacking direction of the cell stack. In this case, the cell stack is pressed in the cell stacking direction by the opposing surface and the ribs, maintaining the preferred cell stacking structure of the cell stack.

[0008] At this time, the opening of the recess formed in the opposite surface of the end plate is closed by the end in the cell stacking direction of the cell stack. This forms the flow path within the recess through which the coolant flows. The section between the inlet and outlet in this flow path is divided by the fins provided at intervals in the vertical direction. The coolant flows in the horizontal direction through the sections in the flow path divided by the fins. The coolant cools the end in the cell stacking direction of the cell stack.

[0009] The fluid in the flow path and the end plate are isolated from each other by a portion of the plastic layer covering the inner surface of the recess and the outer surfaces of the ribs. The end plate and the cell stack are isolated from each other by the portion of the plastic layer covering the opposing surface and the portions of the plastic layer covering the distal end surfaces in the protrusion direction of the ribs.

[0010] From the viewpoint of effectively cooling the end in the cell stacking direction of the cell stack with the coolant flowing through the flow path in the recess of the end plate, the coolant preferably passes through the sections in the flow path which are divided by the fins in a uniform manner.

[0011] However, since the outlet is located at a higher position than the inlet in the flow path in the recess, the coolant flow from the inlet to the outlet tends to be directed upward. As a result, the coolant flows less evenly in the lowest section of the flow path divided by the ribs than in the other divided sections. Therefore, the end section in the cell stacking direction of the cell stack corresponding to the lowest section of the flow path in the recess cannot be easily cooled, resulting in uneven cooling of the end.

[0012] It is therefore the object of the present invention to provide an end plate capable of preventing the cooling of the end from being uneven in the cell stacking direction of a cell stack.

[0013] A means for solving the above-described problem will now be described. To achieve the above-described object, an end plate is provided, which is shaped as a rectangle having a pair of horizontal long sides and a pair of vertical short sides. The end plate is provided at one end in a cell stacking direction of a cell stack in a fuel cell, and is used to supply a coolant to and discharge a coolant from the cell stack. A recess configured to form a flow path in which the coolant flows is open in an opposite surface facing the end in the cell stacking direction of the cell stack and is formed to extend in a horizontal direction along the opposite surface. A plurality of ribs are formed on a bottom surface of the recess.The ribs protrude toward an opening position of the recess and are arranged at intervals in the vertical direction to extend in the horizontal direction. An inlet portion, which allows the coolant to flow into the flow path in the recess from the cell stack, is provided at one end in the horizontal direction of the recess. An outlet hole, which allows the coolant to flow out of the flow path in the recess, is arranged at another end in the horizontal direction of the recess and at a position higher than the inlet portion. A pair of upper and lower inner wall surfaces in the recess are distributed in a portion of the recess connected to the inlet portion, vertically to the outlet hole. An end of a lowermost one of the ribs near the inlet portion is closer to the outlet hole than ends near the inlet portion of the other ribs.

[0014] According to another aspect, an end plate is provided that is shaped as a rectangle having a pair of horizontal long sides and a pair of vertical short sides. The end plate is provided at one end in a cell stacking direction of a cell stack in a fuel cell and is used to supply a coolant to the cell stack and to discharge a coolant from the cell stack. A recess configured to form a flow path into which the coolant flows is open in an opposite surface facing the end in the cell stacking direction of the cell stack and is formed to extend in a horizontal direction along the opposite surface. A plurality of ribs are formed on a bottom surface of the recess.The ribs protrude toward an opening position of the recess and are arranged at intervals in a vertical direction so as to extend in the horizontal direction. An inlet portion that allows the coolant to flow into the flow path in the recess from the cell stack is provided at one end in the horizontal direction of the recess. An outlet hole that allows the coolant to flow out of the flow path in the recess is provided at another end in the horizontal direction of the recess and at a position higher than the inlet portion. A pair of upper and inner wall surfaces in the recess are distributed in a portion of the recess connected to the inlet portion vertically to the outlet hole. An end of a lowermost one of the ribs near the outlet hole is closer to the inlet portion than ends near the outlet hole of the other ribs. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view illustrating a manner in which an end plate is attached to the cell stack of a fuel cell. Fig. 2 is a schematic plan view of the end plate of the Fig. 1, viewed from the cell stack. Fig. 3 is a cross-sectional view of a line AA of the end plate taken from the Fig. 2 is evident. Fig. 4 is a plan view illustrating ribs in an end plate according to a modification.

[0015] An end plate according to a first embodiment will now be described with reference to the Fig. 1 to 3.

[0016] As from the Fig. 1, a fuel cell 1 has a cell stack 2 and an end plate 4 which is arranged at one end in the cell stack direction of the cell stack 2 (in the direction from left to right in the Fig. 1). The end plate 4 is used to cause a fluid, specifically hydrogen (fuel gas), air (oxidizing gas), and cooling water (coolant) to flow through the cell stack 2. The end plate 4 is a metal plate to which pipes 3 through which the fluid flows are connected. The end plate 4 is attached to a casing 1a provided in the fuel cell so as to surround the cell stack 2. The cell stack 2 uses the hydrogen and air supplied and discharged through the end plate 4 to generate power and is cooled by the cooling water supplied and discharged through the end plate 4.

[0017] The Fig. 2 shows schematically, viewed from the cell stack 2, a state of the end plate 4 of the Fig. 1. The end plate 4 is shaped as a rectangle having a pair of horizontal long sides and a pair of vertical short sides. The end plate 4 has an outer edge, a mounting portion 5 extending along the long sides, and the short sides. The end plate 4 is fixed to the housing 1a ( Fig. 1) is fixed to the fixing section 5, for example, with screws. The surface of the fixing section 5 on the side facing the cell stack 2 (the surface on the near side of the sheet of the Fig. 2) defines a mounting surface 6 which is brought into contact with the housing 1a and fixed thereto.

[0018] The end plate 4 has holes 7 to 11 in a part surrounded by the fastening section 5. The holes 7 to 11 extend in the direction of thickness through the end plate 4 (the direction perpendicular to the blade of the Fig. 2). The holes 7 to 11 define flow paths through which the fluid flows. The holes 7, 8, 10, and 11 are open in an opposite surface of the end plate 4, which faces the end in the cell stacking direction of the cell stack 2. Furthermore, the end plate 4 has a recess 14 open in the opposite surface 12 and extends along the opposite surface 12 in the direction of the long side of the end plate 4 (horizontal direction). The hole 9 is open in a bottom surface 14a of the recess 14 at the left end in the horizontal direction. The hole 9 and the recess 14 define a flow path through which the fluid flows.

[0019] When the fastening section 5 of the end plate 4 is fixed to the housing 1a ( Fig. 1), the flow paths defined by the holes 7, 8, 10, 11 are connected to the cell stack 2. At this time, the opening of the recess 14 formed in the opposite surface 12 is closed by the end in the cell stacking direction of the cell stack 2, and a flow path through which cooling water flows is formed in the recess 14. In addition, the right end of the flow path in the recess 14 in the long side direction (the horizontal direction) is connected to a passage 15 for cooling water formed in the cell stack 2.

[0020] The cooling water flows from the passage 15 into the flow path in the recess 14, and then the cooling water flows in the flow path in the direction in which the recess 14 extends and flows out of the hole 9. The right end in the horizontal direction of the recess 14, which is connected to the passage 15, functions as an inlet portion to allow the coolant to flow in from the cell stack 2. The hole 9 functions as an outlet hole through which the cooling water flows out of the recess 14. The hole 9 is arranged at a position higher than the portion (right end portion) of the recess 14 connected to the passage 15 so as to prevent the air in the cooling water from remaining in the flow path in the recess 14.

[0021] The recess 14 has a pair of upper and lower inner wall surfaces 14b, 14c. The upper and lower inner wall surfaces 14b, 14c spread (expand, widen) vertically toward the bore 9 in the portion of the recess 14 connected to the passage 15. The end plate 4 also has ribs 16 projecting from the bottom surface 14a of the recess 14. The ribs 16 are provided at intervals in the vertical direction and formed to extend in the horizontal direction. The end near the passage 15 (the right end) of the lowest one of the ribs 16 is closer to the bore 9 (to the left) than the ends near the passage 15 of the other ribs 16.

[0022] The Fig. 3 shows the end plate 4 in the Fig. 2 as viewed from the direction of arrows AA. As can be seen from the drawing, the ribs 16 protrude from the bottom surface 14a of the recess 14 to the opening position of the recess 14 in the opposing surface 12. The opposing surface 12, the inner surface of the recess 14, and the outer surfaces of the ribs 16 in the end plate 4 are covered by a plastic layer 13. When the mounting surface 6 of the fixing portion 5 of the end plate 4 is brought into contact with the casing 1a and fixed thereto, the opposing surface 12 and the ribs 16 press the cell stack 2 in the cell stacking direction, so that a preferable cell stacking structure of the cell stack 2 is maintained.

[0023] When the fastening portion 5 of the end plate 4 is fastened to the housing 1a, the plastic layer 13 covering the opposite surface 12 and the portions of the plastic layer 13 covering the distal end faces in the protruding direction of the ribs 16 contact the end of the cell stack 2 in the cell stacking direction. As a result, the end plate 4 and the end in the cell stacking direction of the cell stack 2 are insulated from each other by the portion of the plastic layer 13 covering the opposite surface 12 and the portions of the plastic layer 13 covering the distal end faces in the protruding direction of the ribs 16. The plastic layer 13 insulates the fluid in the passages formed by the holes 7, 8, 10, and 11 ( Fig. 2) flow paths formed by the end plate 4 and isolates the fluid (cooling water) in the flow path formed by the bore 9 and the recess 14 of the end plate 4.

[0024] The end plate 4 of the embodiment described above achieves the following advantages.

[0025] (1) In the end plate 4, the recess 14 has a pair of upper and lower inner wall surfaces 14b, 14c. In the portion of the recess 14 connected to the passage 15, the vertical distance of the upper and inner wall surfaces 14b, 14c increases toward the bore 9. In addition, the bore 9 is located at a position higher than the portion of the recess 14 connected to the passage 15. Therefore, when the coolant flows into the flow path in the recess 14 from the passage 15 and into the portion in the recess 14 where the upper and lower inner wall surfaces 14b, 14c are vertically distributed, the coolant does not flow downward smoothly. However, the structure discussed below prevents such a problem.

[0026] In the recess 14 the end is located near the passage 15 (the right end in the Fig. 2) the lowermost one of the ribs 16, which are provided at intervals in the vertical direction and are formed to extend in the horizontal direction, is closer to the bore 9 (at the left end) than the ends near the passage 15 of the other ribs 16. As a result, the lowermost one of the sections divided by the ribs 16 of the flow path in the recess 14 is expanded in the portion connected to the passage 15. Therefore, when the cooling water flows from the passage 15 into the section in the recess 14 where the upper and inner wall surfaces 14b, 14c are vertically distributed, the cooling water flows smoothly downward.

[0027] As described above, the cooling water is prevented from flowing less evenly into the lowest section of the flow path divided by the ribs 16 in the recess 14 than into the other sections. This configuration prevents the end section in the cell stacking direction of the cell stack 2 corresponding to the lowest section of the flow path in the recess 14 from being insufficiently cooled, thereby preventing the end from being cooled unevenly. Second embodiment

[0028] An end plate 4 according to a second embodiment will now be described with reference to the Fig. 4 described.

[0029] As from the Fig.As can be seen from Figure 4, the end plate 4 of this embodiment differs from the first embodiment in the configuration of the lowest rib 16. In particular, the end near the bore 9 (the left end) of the lowest rib 16 is closer to the passage 15 (to the right) than the ends near the bore 9 of the other ribs 16.

[0030] The end plate 4 of the above-described embodiment achieves the following advantage.

[0031] (2) In the recess 14, the end near the hole 9 (the left end) of the lowest one of the ribs 16 is closer to the passage 15 (to the right) than the ends near the hole 9 of the other ribs 16. This reduces the flow resistance of the cooling water in the flow direction of the cooling water in the lowest one of the sections divided by the ribs 16 in the flow path of the recess 14. Therefore, when the cooling water flows from the passage 15 into the section in the recess 14 where the upper and lower inner wall surfaces 14b, 14c are distributed vertically, the cooling water flows downward evenly.

[0032] As described above, the cooling water is prevented from flowing less evenly into the lowest one of the sections divided by the ribs 16 of the flow path in the recess 14. This configuration prevents the end section in the cell stacking direction of the cell stack 2 corresponding to the lowest section of the flow path in the recess 14 from being insufficiently cooled, thereby preventing the end from being cooled unevenly.

Claims

[1] An end plate (4) shaped as a rectangle having a pair of horizontal long sides and a pair of vertical short sides, the end plate (4) being provided at one end in a cell stacking direction of a cell stack (2) in a fuel cell (1) and being used to supply a coolant to the cell stack (2) and to discharge the coolant from the cell stack (2), wherein a recess (14) configured to form a flow path in which the coolant flows, is open in an opposite surface (12) directed toward the end in the cell stacking direction of the cell stack (2) and is formed to extend in a horizontal direction along the opposite surface (12), a plurality of ribs (16) are formed on a bottom surface (14a) of the recess (14), and the ribs (16) project to an opening position of the recess (14) and are arranged at intervals in a vertical direction so as to extend in the horizontal direction, an inlet portion is provided at one end in the horizontal direction of the recess (14), which allows the coolant to flow from the cell stack (2) into the flow path in the recess (14), an outlet hole (9) allowing the coolant to flow out of the flow path in the recess (14) is provided at another end in the horizontal direction of the recess (14) and at a position higher than the inlet portion, whereby the end plate (4) characterized byis that a pair of upper and lower inner wall surfaces (14b, 14c) in the recess (14) are distributed vertically to the outlet bore (9) in a portion of the recess (14) connected to the inlet portion, and an end close to the inlet section of a lowermost one of the ribs (16) is closer to the outlet bore (9) than ends close to the inlet section of the other ribs (16). [2] An end plate (4) shaped as a rectangle having a pair of horizontal long sides and a pair of vertical short sides, the end plate (4) being provided at one end in a cell stacking direction of a cell stack (2) in a fuel cell (1) and being used to supply a coolant to the cell stack (2) and to discharge a coolant from the cell stack (2), wherein a recess (14) configured to form a flow path in which the coolant flows, open to an opposite surface (12) directed toward the end in the cell stacking direction of the cell stack (2), and formed to extend in a horizontal direction along the opposite surface (12), a plurality of ribs (16) are formed on a bottom surface (14a) of the recess (14), the ribs (16) projecting to an opening position of the recess (14) and being arranged at intervals in a vertical direction to extend in the horizontal direction, an inlet portion allowing the coolant to flow from the cell stack (2) into the flow path in the recess (14) is provided at one end in the horizontal direction of the recess (14), an outlet hole (9) allowing the coolant to flow out of the flow path in the recess (14) is provided at another end in the horizontal direction of the recess (14) and at a position higher than the inlet portion, whereby the end plate (4) characterized by is that a pair of upper and lower inner wall surfaces (14b, 14c) in the recess (14) are distributed vertically to the outlet bore (9) in a portion of the recess (14) connected to the inlet portion, and an end near the outlet bore (9) of a lowermost one of the ribs (16) is closer to the inlet section than ends near the outlet bore (9) of the other ribs (16).

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