JP2018045775A - Manufacturing method for fuel cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a fuel cell stack that facilitates assembling work, and can reduce assembly manhours and reduce costs.SOLUTION: The manufacturing method for a fuel cell stack 1 has: a bolt inserting step in which a stepped bolt 100 is inserted into across an end plate mounting hole 101 of a second end plate 82 and a connection bar mounting hole 102 of connection bars 83 and 84; a seating step in which the second end plate 82 is abutted to the connection bars 83 and 84 in an A direction; and a fastening step in which the second end plate 82 is fastened to the connection bars 83 and 84 in the A direction. The stepped bolt 100 has a base shaft part 10A that guides the first end plate 81, the second end plate 82 and the connection bars 83 and 84 to approach in the A direction. In the bolt inserting step, the stepped bolt 100 is inserted into so that the base shaft part 10A is positioned, in the A direction, across the end plate mounting hole 101 and the connection bar mounting hole 102.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a method for manufacturing a fuel cell stack.

A fuel cell stack mounted on a vehicle or the like includes a cell stack and a casing that stores the cell stack (see, for example, Patent Document 1 below).
The cell stack is configured by stacking a plurality of unit cells. The unit cell includes a membrane electrode structure (MEA) configured by sandwiching a solid polymer electrolyte membrane between an anode electrode and a cathode electrode from both sides, and a separator that sandwiches the membrane electrode structure.

The casing includes a pair of end plates that sandwich the cell stack from both sides in the stacking direction, a connecting bar that spans between the pair of end plates, a side panel that surrounds the periphery of the cell stack from a direction orthogonal to the stacking direction, have.
The end plate and the connection bar are fastened by a fastening member inserted into the end plate attachment hole and the connection bar attachment hole in a state of being abutted with each other in the stacking direction of the cell stack. For example, Patent Document 2 below discloses a configuration in which a cylindrical knock is disposed in the end plate mounting hole and the connecting bar mounting hole. The cylindrical knock is disposed across the end plate mounting hole and the connecting bar mounting hole and is extrapolated to the fastening member.

  In the fuel cell stack described above, hydrogen gas is supplied as fuel gas to the anode electrode, and air is supplied as oxidant gas to the cathode electrode. As a result, hydrogen ions generated by the catalytic reaction at the anode electrode permeate the solid polymer electrolyte membrane and move to the cathode electrode, and the cathode electrode causes an electrochemical reaction with oxygen in the air to generate power.

JP 2014-216269 A JP 2013-179032 A

  However, the above-described configuration including the cylindrical knock has a problem that the number of parts is large, the number of steps for assembling is increased, and the cost is increased.

  The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a method for manufacturing a fuel cell stack that can facilitate assembly work, reduce assembly man-hours, and reduce costs. One of them.

  In order to achieve the above object, the invention described in claim 1 includes a first end plate (for example, the first end plate 81 in the embodiment) and a plurality of fuel cells (for example, the unit cell 2 in the embodiment). Stacking the cell stack stacked in the first direction (for example, the A direction in the embodiment) and the second end plate (for example, the second end plate 82 in the embodiment) in this order in the first direction; A connecting member disposing step of disposing a connecting member (for example, connecting bars 83 and 84 in the embodiment) between the first end plate and the second end plate; and the first end plate and the second end plate In a state where there is a gap in the first direction (for example, the gap S1 in the embodiment) between any one and the connecting member, the end plate mounting hole ( For example, a fastening member inserting step of inserting a fastening member into the end plate attaching hole 101) and the connecting member attaching hole (for example, the connecting bar attaching hole 102 in the embodiment) in the embodiment, the first end plate, and the second end plate. An end plate is moved closer in the first direction, a seating step of abutting the one end plate and the connecting member in the first direction, and the one end plate and the connecting member are moved by the fastening member. A fastening step of fastening in a first direction, wherein the fastening member guides the approaching movement of the first end plate, the second end plate, and the connecting member in the first direction in the seating step. A positioning portion (for example, the base shaft portion 10A in the embodiment), and in the fastening member insertion step, the positioning portion is Serial end plate mounting hole and the connecting member attachment hole for inserting the fastening member to be positioned across the first direction.

  In the invention described in claim 2, in the first direction, the length of the large diameter portion is longer than the length of the end plate mounting hole plus the gap, and the end plate mounting hole and the It is below the length which added each length along the said 1st direction of a connection member attachment hole, and in the said fastening member insertion process, the level | step difference surface between the said large diameter part of the said fastening member and the said small diameter part ( For example, the fastening member may be inserted so that the stepped surface 10C) in the embodiment is located in the connecting member mounting hole.

  In the invention described in claim 3, the fastening member includes the positioning portion and a screw portion (for example, a male screw portion 10B in the embodiment) provided on a distal end side of the positioning portion, In the fastening member inserting step, a part of the screw portion may be screwed into the connecting member mounting hole.

  In the invention described in claim 4, in the fastening member inserting step, the fastening member in which the positioning portion and the screw portion having a smaller diameter than the positioning portion are integrally formed may be used.

According to the invention described in claim 1, in the fastening member inserting step, the small diameter portion is in a state where there is a gap in the first direction between one of the first end plate and the second end plate and the connecting member. By inserting the fastening member so that the large diameter portion is located in the end plate attachment hole and the connection member attachment hole in the first direction while being located in the connection member attachment hole, the distal end portion of the fastening member is connected to the connection member. The fastening member can be made to function as a guide in the subsequent seating step without falling off from the mounting hole. That is, it is possible to prevent the positional displacement between the end plate and the connecting member by abutting one end plate and the connecting member in the first direction along the large diameter portion of the fastening member that forms the guide. Thus, in the present invention, since the assembly is performed in a state where the end plate and the connecting member are positioned by the fastening member, it is possible to perform an efficient and efficient assembly operation.
Furthermore, in this invention, it replaces with the cylindrical knock used previously, and receives the shear load which acts between an end plate and a connection member in the large diameter part of a fastening member. As a result, a cylindrical knock becomes unnecessary and the number of assembly steps can be reduced, so that the cost for the production line can be reduced.

  According to the second aspect of the present invention, not only can the fastening member function as a guide in the seating process, but also the end plate and the connecting member can be satisfactorily fastened by the fastening member after the seating process.

  According to the third aspect of the present invention, the fastening member can be fixed to the connecting member by screwing a part of the screw portion of the fastening member into the connecting member mounting hole. The members are unlikely to fall off and wobble, and the positional displacement between the end plate and the connecting member can be further prevented. Thereby, the seating process can be performed in a stable state using the positioning portion of the fastening member as a guide.

  According to the invention described in claim 4, the positioning portion of the fastening member is in close contact with the inner peripheral surface of both the end plate small diameter portion and the connecting bar large diameter portion, and the reaction gas leaking from the cell stack is Further, it is possible to suppress the flow out of the first direction through the end plate mounting hole and the connecting member mounting hole and the fastening member.

The disassembled perspective view which looked at the fuel cell stack of the embodiment from the first end plate side. The exploded perspective view of a unit cell. Sectional drawing equivalent to the III-III line of FIG. Sectional drawing equivalent to the IV-IV line of FIG. The disassembled perspective view which looked at the fuel cell stack from the 2nd end plate side. Sectional drawing corresponded in the VI-VI line of FIG. The flowchart for demonstrating the manufacturing method of a fuel cell stack. Process drawing for demonstrating the manufacturing method (lamination process) of a fuel cell stack. Process drawing for demonstrating the manufacturing method (compression process) of a fuel cell stack. Process drawing for demonstrating the manufacturing method (connection bar arrangement | positioning process) of a fuel cell stack. Process drawing for demonstrating the manufacturing method (step bolt insertion process) of a fuel cell stack. The figure which shows the state which inserted the stepped volt | bolt. Process drawing for demonstrating the manufacturing method (sitting process) of a fuel cell stack. Process drawing for demonstrating the manufacturing method (sitting process) of a fuel cell stack. Process drawing for demonstrating the manufacturing method of a fuel cell stack. It is process drawing for demonstrating the manufacturing method of a fuel cell stack. (A), (b) is a figure which shows the modification of a fuel cell stack.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

(First embodiment)
[Fuel cell stack]
FIG. 1 is an exploded perspective view of the fuel cell stack 1 of the present embodiment as viewed from the first end plate 81 side.
As shown in FIG. 1, the fuel cell stack 1 of the present embodiment is mounted under a motor room or a floor defined in a front portion of a vehicle (not shown). The fuel cell stack 1 is used, for example, to supply power to a drive motor. In the fuel cell stack 1 of the present embodiment, for example, the A direction (first direction) in the figure is the vehicle width direction, the B direction is the vehicle front-rear direction, and the C direction is the vehicle vertical direction. Mounted on.

The fuel cell stack 1 mainly includes a cell stack 3 and a casing 4 that houses the cell stack 3.
The cell stack 3 is configured by stacking a plurality of unit cells (fuel cell) 2 in the A direction. In the following description, in the A direction, the B direction, and the C direction described above, the direction approaching the center portion of the cell stack 3 is referred to as the inside, and the direction away from the center portion of the cell stack 3 is referred to as the outside. is there.

<Unit cell>
FIG. 2 is an exploded perspective view of the unit cell 2.
As shown in FIG. 2, the unit cell 2 includes, for example, a pair of separators 21 and 22, and a membrane electrode structure 23 (hereinafter simply referred to as MEA 23) sandwiched between the separators 21 and 22. . The MEA 23 includes a solid polymer electrolyte membrane 31, and an anode electrode 32 and a cathode electrode 33 that sandwich the solid polymer electrolyte membrane 31 from both sides in the A direction.

  The anode electrode 32 and the cathode electrode 33 are a gas diffusion layer made of carbon paper or the like, and an electrode catalyst layer formed by uniformly applying porous carbon particles having a platinum alloy supported on the surface to the surface of the gas diffusion layer. And have.

  The solid polymer electrolyte membrane 31 is formed of a material obtained by impregnating perfluorosulfonic acid polymer with water, for example. The solid polymer electrolyte membrane 31 has a larger front view profile as viewed from the A direction than the anode electrode 32 and the cathode electrode 33. In the example of FIG. 2, an anode electrode 32 and a cathode electrode 33 are superimposed on the central portion of the solid polymer electrolyte membrane 31. The outer periphery of the solid polymer electrolyte membrane 31 protrudes in a frame shape with respect to the anode electrode 32 and the cathode electrode 33.

  The separators 21 and 22 of the unit cell 2 are a first separator 21 arranged on the anode electrode 32 side of the MEA 23 and a second separator 22 arranged on the cathode electrode 33 side of the MEA 23. In the following description, the same components in the separators 21 and 22 will be described with the same reference numerals.

Each separator 21, 22 has a separator plate 35 and a covering member 36 that covers the outer periphery of the separator plate 35.
The separator plate 35 is configured by a rectangular metal plate or a carbon plate whose longitudinal direction is the B direction. In the example of FIG. 2, the separator plate 35 is formed in the same shape as the solid polymer electrolyte membrane 31 in front view. The separator plate 35 overlaps the MEA 23 when viewed from the A direction.

3 is a cross-sectional view corresponding to the line III-III in FIG.
As shown in FIG. 3, the covering member 36 is made of an elastically deformable material such as rubber. The covering member 36 is in close contact with the outer periphery of the solid polymer electrolyte membrane 31 in the A direction.

As shown in FIG. 2, at each corner of the unit cell 2, an inlet side gas communication hole (oxidant gas inlet communication hole 41i and fuel gas inlet communication hole 42i) and an outlet side gas communication hole (oxidant gas outlet) are provided. A communication hole 41o and a fuel gas outlet communication hole 42o) are formed. Each oxidant gas inlet communication hole 41i, 41o, 42i, 42o penetrates the unit cell 2 in the A direction.
In the example shown in FIG. 2, an oxidant gas inlet communication hole 41 i for supplying an oxidant gas (for example, air) is formed in the upper right corner of the unit cell 2. A fuel gas inlet communication hole 42 i for supplying fuel gas (for example, hydrogen or the like) is formed in the lower right corner of the unit cell 2.
Further, an oxidant gas outlet communication hole 41o for discharging the used oxidant gas is formed in the lower left corner of the unit cell 2. A fuel gas outlet communication hole 42o for discharging used fuel gas is formed in the upper left corner of the unit cell 2.

In the unit cell 2, refrigerant inlet communication holes 43 i are formed in portions located inside the B direction with respect to the oxidant gas inlet communication holes 41 i and 42 i, respectively.
In the unit cell 2, a refrigerant outlet communication hole 43o is formed in a portion located inside the B direction with respect to the oxidant gas outlet communication holes 41o and 42o. Note that the pair of refrigerant inlet communication holes 43i and the pair of refrigerant outlet communication holes 43o are disposed at positions facing each other in the C direction with the anode electrode 32 and the cathode electrode 33 interposed therebetween.

The central part of each separator 21, 22 (separator plate 35) is formed in an uneven shape by press molding or the like. Of the separators 21 and 22, the surface facing the MEA 23 forms a fuel gas flow channel 45 and an oxidant gas flow channel 46, respectively, with the MEA 23.
Specifically, a fuel gas channel 45 is formed between the surface of the first separator 21 facing the anode electrode 32 and the anode electrode 32 of the MEA 23. The fuel gas channel 45 communicates with the fuel gas inlet communication hole 42i and the fuel gas outlet communication hole 42o, respectively.

  An oxidant gas flow path 46 is formed between the surface of the second separator 22 facing the cathode electrode 33 and the cathode electrode 33 of the MEA 23. The oxidant gas channel 46 communicates with the oxidant gas inlet communication hole 41i and the oxidant gas outlet communication hole 41o, respectively.

  As shown in FIG. 3, in the cell stack 3, the first separator 21 of one unit cell 2 and the second separator 22 of another unit cell 2 adjacent to one unit cell 2 are overlapped. Thus, they are stacked in the A direction. A refrigerant channel 55 is formed between the first separator 21 of one unit cell 2 and the second separator 22 of another unit cell 2. As shown in FIG. 2, the refrigerant flow passage 55 communicates with the refrigerant inlet communication hole 43i and the refrigerant outlet communication hole 43o, respectively. In addition, as a refrigerant | coolant which distribute | circulates the refrigerant | coolant flow path 55, a pure water, ethylene glycol, etc. are used suitably, for example.

  Note that the stacked structure of the unit cells 2 is not limited to the above-described configuration. For example, a unit cell may be constituted by three separators and two MEAs sandwiched between the separators. In addition, the design of the layout of each communication hole can be changed as appropriate.

  As shown in FIG. 3, a first terminal plate 61 is disposed on one side in the A direction with respect to the cell stack 3. The outer shape of the first terminal plate 61 in front view is smaller than that of the separators 21 and 22. The first terminal plate 61 is connected to the first separator 21 on the anode electrode 32 of a unit cell (hereinafter, referred to as a first end cell 2a) positioned in one of the cell stacks 3 (each unit cell 2) in the A direction. Conducted through. The first terminal plate 61 is formed with an output terminal 63 (see FIG. 1) that protrudes outward in the A direction.

  A first insulator 66 is disposed outside the first terminal plate 61 in the A direction. The first insulator 66 has a front view outer shape larger than that of the first terminal plate 61. The first insulator 66 is thicker in the A direction than the first terminal plate 61.

A housing portion 71 that is recessed toward the outside in the A direction is formed at the center of the first insulator 66. The first terminal plate 61 described above is accommodated in the accommodating portion 71.
The outer peripheral portion of the first insulator 66 (the portion located outside the accommodating portion 71) is in close contact with the first separator 21 (the covering member 36) in the first end cell 2a from the outside in the A direction. An oxidant gas inlet connection hole 72 and a fuel gas inlet connection hole (not shown) communicating with the oxidant gas inlet communication holes 41i and 42i described above are formed on the outer periphery of the first insulator 66, respectively. In addition, an oxidant gas outlet connection hole and a fuel gas outlet connection hole (not shown) that communicate with the oxidant gas outlet communication holes 41o and 42o described above are formed on the outer periphery of the first insulator 66, respectively.

4 is a cross-sectional view corresponding to the line IV-IV in FIG.
As shown in FIG. 4, the second terminal plate 62 is disposed on the other side in the A direction with respect to the cell stack 3. The second terminal plate 62 is electrically connected to the cathode electrode 33 of the unit cell (hereinafter referred to as the second end cell 2b) located on the other side in the A direction among the unit cells 2 via the second separator 22. Yes. The second terminal plate 62 is formed with an output terminal 64 (see FIG. 5) that protrudes outward in the A direction.

  A second insulator 67 is disposed outside the second terminal plate 62 in the A direction. The second insulator 67 has a front view outer shape larger than that of the second terminal plate 62. The second insulator 67 is thicker in the A direction than the second terminal plate 62.

A housing portion 73 that is recessed toward the outside in the A direction is formed at the center of the second insulator 67. The second terminal plate 62 described above is accommodated in the accommodating portion 73.
The outer peripheral portion of the second insulator 67 (the portion located outside the accommodating portion 73) is in close contact with the second separator 22 (the covering member 36) in the second end cell 2b from the outside in the A direction. In addition, a refrigerant inlet connection hole 74 and a refrigerant outlet connection hole (not shown) that communicate with the refrigerant inlet communication holes 43i and 43o described above are formed on the outer periphery of the second insulator 67, respectively.

<Casing>
As shown in FIG. 1, the casing 4 is formed in a box shape that is slightly larger than the cell stack 3. The casing 4 stores the cell stack 3 therein. Specifically, the casing 4 connects the first end plate 81 and the second end plate 82 that sandwich the cell stack 3 from both sides in the A direction, and the opposite sides of the end plates 81 and 82 in the A direction. A first connecting bar (connecting member) 83 and a second connecting bar (connecting member) 84, and four side panels 80 surrounding the cell stack 3.

  As shown in FIGS. 3 and 4, the end plates 81 and 82 are formed in a rectangular shape having a front view outer shape larger than that of the unit cell 2. As shown in FIG. 3, the first end plate 81 is located on one side of the cell stack 3 in the A direction with the first terminal plate 61 and the first insulator 66 sandwiched between the cell stack 3 and the first end plate 81. Has been placed.

  As shown in FIG. 1, a gas inlet hole (oxidant gas inlet hole 85i and fuel gas inlet hole 86i) and a gas outlet hole (oxidant gas outlet hole 85o and fuel gas are provided at each corner of the first end plate 81. An outlet hole 86o) is formed. The oxidant gas inlet holes 85i and 86i communicate with the oxidant gas inlet communication holes 41i and 42i through the corresponding gas inlet connection holes (for example, the oxidant gas inlet connection hole 72) of the first insulator 66, respectively. The oxidant gas outlet holes 85o and 86o communicate with the oxidant gas outlet communication holes 41o and 42o through the corresponding gas outlet connection holes of the first insulator 66, respectively.

  As shown in FIG. 4, the second end plate 82 is placed on the other side in the A direction with respect to the cell stack 3 with the second terminal plate 62 and the second insulator 67 sandwiched between the cell stack 3 and the second end plate 82. Has been placed.

FIG. 5 is an exploded perspective view of the fuel cell stack 1 as viewed from the second end plate 82 side.
As shown in FIG. 5, the second end plate 82 has a pair of refrigerant inlet holes 95i and a pair of refrigerant outlet holes 95o. The refrigerant inlet hole 95i communicates with the refrigerant inlet communication hole 43i through the corresponding refrigerant inlet connection hole 74 (see FIG. 4) of the second insulator 67. The refrigerant outlet hole 95 o communicates with the refrigerant outlet communication hole 43 o through the corresponding refrigerant outlet connection hole of the second insulator 67.

  As shown in FIG. 1, the 1st connection bar 83 and the 2nd connection bar 84 are formed in the plate shape extended along A direction. In addition, the cross-sectional shape of each connection bar 83 and 84 can change suitably, such as rectangular shape and circular shape.

The connecting bars 83 and 84 are fastened to the end plates 81 and 82 by a pair of stepped bolts (fastening members) 100 in a state where both end faces in the A direction are butted against the end plates 81 and 82 in the A direction. ing. Specifically, the first connection bar 83 connects the long side portions of the end plates 81 and 82 to the cell stack 3 on both sides in the C direction. The second connecting bar 84 connects the short side portions of the end plates 81 and 82 to both sides of the cell stack 3 in the B direction.
Note that three or more stepped bolts 100 may be provided for each of the connecting bars 83 and 84.

  Each side panel 80 is disposed around the cell stack 3 (outside in the B direction and outside in the C direction). Each side panel 80 surrounds the cell stack 3, the terminal plates 61 and 62, the insulators 66 and 67, the end plates 81 and 82, and the connecting bars 83 and 84 from the outside in the B direction and the outside in the C direction.

  Next, the fastening structure between the end plates 81 and 82 and the connecting bars 83 and 84 will be described in detail. However, the fastening structure between the end plates 81 and 82 and the connecting bars 83 and 84 has the same configuration. Therefore, in the following description, the fastening structure of the first end plate 81 and the first connecting bar 83 will be mainly described, and the description of the fastening structure of other parts will be omitted.

6 is a cross-sectional view corresponding to the line VI-VI in FIG.
As shown in FIG. 6, an end plate mounting hole 101 is formed in a portion of the first end plate 81 that overlaps the first connecting bar 83 when viewed from the A direction. The end plate attachment hole 101 is a circular through hole that penetrates the first end plate 81 in the A direction. The end plate mounting hole 101 has a multi-stage shape with a smaller inner diameter as it is located on the inner side in the A direction. Specifically, the end plate mounting hole 101 has an end plate large diameter portion 101a located on the outer side in the A direction and an end plate small diameter portion 101b connected to the inner side in the A direction with respect to the end plate large diameter portion 101a. doing. In the present embodiment, two end plate mounting holes 101 are formed at an interval in the B direction shown in FIG.

  The length of the end plate large diameter portion 101a in the A direction is shorter than the end plate small diameter portion 101b. Of the opening edges of the end plate mounting hole 101, chamfered portions 101d are formed at least at both end opening edges in the A direction of the end plate small diameter portion 101b. The chamfering may be round chamfering or flat chamfering.

  A connection bar attachment hole (connection member attachment hole) 102 is formed in a portion of the first connection bar 83 that overlaps the end plate attachment hole 101 when viewed from the A direction. The connection bar mounting hole 102 extends along the A direction and opens on the outer end surface 87 of the first connection bar 83 in the A direction. The outer opening in the A direction in the connecting bar mounting hole 102 communicates with the end plate mounting hole 101.

  The connecting bar mounting hole 102 has a multistage shape with a smaller inner diameter as it is located on the inner side in the A direction. Specifically, the connecting bar mounting hole 102 has a connecting bar large diameter portion 102a located on the outer side in the A direction and a connecting bar small diameter portion 102b connected to the inner side in the A direction with respect to the connecting bar large diameter portion 102a. doing. The inner diameter of the connecting bar large diameter portion 102a is equal to the inner diameter of the end plate small diameter portion 101b. Of the connecting bar mounting hole 102, at least the connecting bar small-diameter portion 102b is a female screw hole.

  Of the connecting bar mounting hole 102, a chamfered portion 102d is formed at least on the outer opening edge in the A direction of the connecting bar large diameter portion 102a. The chamfering may be round chamfering or flat chamfering.

  The first end plate 81 and the first connection bar 83 are fastened by a stepped bolt 100 inserted into the end plate attachment hole 101 and the connection bar attachment hole 102. The stepped bolt 100 positions the first end plate 81 and the first connecting bar 83 and receives a shear load and a tensile load acting between the first end plate 81 and the first connecting bar 83. is there.

  As shown in FIG. 6, the stepped bolt 100 has a head part 100a and a shaft part 100b that are coaxially connected to each other, and a part of the shaft part 100b is a male screw. The shaft portion 100b is a columnar base shaft portion (positioning portion) 10A and a male screw portion that is formed with a smaller diameter than the base shaft portion 10A and protrudes from a central region of one end surface of the base shaft portion 10A and is threaded on the outer periphery thereof. (Screw part) 10B. In addition, an annular step surface 10C is formed on the shaft portion 100b between the base shaft portion 10A and the male screw portion 10B and on one end surface of the base shaft portion 10A on the male screw portion 10B side. A chamfered portion 10d is formed on the periphery of the step surface 10C. The chamfering may be round chamfering or flat chamfering.

In the stepped bolt 100 of the present embodiment, the male screw portion 10B of the shaft portion 100b is screwed into the connecting bar small diameter portion 102b, and the columnar base shaft portion 10A is connected to the inside of the end plate small diameter portion 101b. It is inserted so as to straddle the large diameter portion 102a.
Specifically, the step surface 10C in the base shaft portion 10A of the stepped bolt 100 faces the connecting bar connecting surface 102c that connects the connecting bar large diameter portion 102a and the connecting bar small diameter portion 102b from the outside in the A direction.

  Further, the seating surface 100c of the stepped bolt 100 is in contact with the end plate connecting surface 101c between the end plate large diameter portion 101a and the end plate small diameter portion 101b from the outside in the A direction. In this case, a part of the head part 100a is accommodated in the end plate large diameter part 101a. Thereby, the protrusion amount to the outer side of the A direction of the head 100a from the 1st end plate 81 is suppressed.

  In this embodiment, the length L in the A direction of the base shaft portion 10A of the stepped bolt 100 is the length L1 in the A direction of the end plate small diameter portion 101b and the length L2 in the A direction of the connecting bar large diameter portion 102a. The length is smaller than the combined length L3 (L <L3 = L1 + L2). The length L in the A direction in the base shaft portion 10A will be described in detail in a manufacturing method described later.

  Further, the outer diameter of the base shaft portion 10A of the stepped bolt 100 is smaller than the inner diameters of the end plate small diameter portion 101b and the connecting bar large diameter portion 102a.

  For example, a hexagonal bolt is preferably used as the stepped bolt 100 of the present embodiment. However, the stepped bolt 100 is not limited to a hexagon bolt, and may be a hexagon socket head bolt.

[Method of manufacturing fuel cell stack]
Next, a method for manufacturing the above-described fuel cell stack 1 will be described.

FIG. 7 is a flowchart for explaining a method of manufacturing the fuel cell stack 1.
As shown in FIG. 7, the manufacturing method of the fuel cell stack 1 of the present embodiment includes a stacking step S1, a compression step S2, a compression release step S3, a connecting bar arrangement step S4, and a stepped bolt insertion step S5. The seating step S6 and the fastening step S7 are mainly provided.

FIG. 8 is a process diagram for explaining the method for manufacturing the fuel cell stack 1 (stacking step S1).
First, the laminator 150 used for manufacturing the fuel cell stack 1 will be described. In the following description, the above-described A direction will be described as the vertical direction.
As illustrated in FIG. 8, the laminating machine 150 includes a base member 151 and a pressing member 152 disposed above the base member 151 and facing the base member 151 in the A direction. The pressing member 152 is movable in the A direction with respect to the base member 151 by a driving mechanism (not shown).

  In the stacking step S1, as shown in FIG. 8, on the base member 151, a first end plate 81, a first insulator 66, a first terminal plate 61 (see FIG. 3), a cell stack 3 (a plurality of unit cells 2). ), The second terminal plate 62 (see FIG. 4), the second insulator 67, and the second end plate 82 are sequentially stacked in the A direction.

  In the following description, the laminated body of the first end plate 81, the first insulator 66, the first terminal plate 61, the cell laminated body 3, the second terminal plate 62, the second insulator 67, and the second end plate 82 will be described. This is simply referred to as a laminate 160. In the present embodiment, for convenience, a method of performing the stacking step S1 by placing the first end plate 81 on the base member 151 will be described. However, the stacking step by placing the second end plate 82 on the base member 151 is described. S1 may be performed.

FIG. 9 is a process diagram for explaining the method for manufacturing the fuel cell stack 1 (the compression step S2 and the compression release step S3).
In the compression step S <b> 2, as shown in FIG. 9, the pressing member 152 is lowered and the laminate 160 is compressed downward in the A direction between the base member 151 and the pressing member 152. At this time, the pressing member 152 is lowered until the length of the cell stack 3 in the A direction becomes a specified stack length (for example, a length equivalent to the cell stack 3 of the assembled fuel cell stack 1 described above).

  In the compression release step S3, the pressing member 152 is raised to release the compression load applied to the laminate 160 from the laminator 150. Then, the second end plate 82 of the stacked body 160 is pushed upward in the A direction by the restoring force of the unit cell 2 or the like. Thereby, the space | interval of the A direction between the 1st end plate 81 and the 2nd end plate 82 expands rather than the space | interval at the time of compression process S2.

FIG. 10 is a process diagram for explaining the method for manufacturing the fuel cell stack 1 (connection bar arrangement step S4).
In the connection bar arrangement step S <b> 4 shown in FIG. 10, the connection bars 83 and 84 are arranged between the first end plate 81 and the second end plate 82. Specifically, the connecting bars 83 and 84 are arranged on the first end plate 81 in a state where the corresponding end plate mounting holes 101 and connecting bar mounting holes 102 are aligned with each other. At this time, a gap S <b> 1 is formed in the A direction between the second end plate 82 and the first connection bar 83 and between the second end plate 82 and the second connection bar 84.

  The stepped bolt insertion step S5 of the present embodiment includes a first bolt insertion step and a second bolt insertion step.

FIG. 11 is a process diagram for explaining a method for manufacturing the fuel cell stack 1 (stepped bolt insertion process S5).
In the stepped bolt insertion step S5 shown in FIG. 11, the stepped bolt 100 is inserted into the end plate mounting hole 101 and the connecting bar mounting hole 102 on the first end plate 81 side and the second end plate 82 side, respectively.

FIG. 12 is a process diagram for explaining a method of manufacturing the fuel cell stack 1 (first bolt insertion process).
In the first bolt insertion step shown in FIG. 12, there is a step in the end plate mounting hole 101 and the connecting bar mounting hole 102 with no gap in the A direction between the first end plate 81 and the connecting bars 83, 84. Insert the bolt 100. At this time, in the stepped bolt 100, the chamfered portion 10d side formed on the stepped surface 10C of the shaft portion 100b is guided by the chamfered portion 102d of the connecting bar mounting hole 102 and inserted into the connecting bar mounting hole 102. Then, the male threaded portion 10B of the stepped bolt 100 is inserted while being screwed into the connecting bar mounting hole 102, and the first end plate 81 and the first connecting bar 83, and the first end plate 81 and the second connecting bar 84 are connected. Each is fastened with a stepped bolt 100. At this time, it is preferable to provide a gap between the stepped surface 10C of the stepped bolt 100 and the connecting bar connecting surface 102c.

FIG. 13 is a process diagram for explaining a method for manufacturing the fuel cell stack 1 (second bolt insertion process).
In the second bolt insertion step shown in FIG. 13, a step is provided in the end plate mounting hole 101 and the connecting bar mounting hole 102 with a gap S1 in the A direction between the second end plate 82 and the connecting bars 83 and 84. Insert the attached bolt 100. At this time, the stepped bolt 100 has a chamfered portion 10d side formed on the stepped surface 10C of the shaft portion 100b as shown in FIG. Is inserted. Then, at least a part of the male screw portion 10B inserted into the connecting bar mounting hole 102 through the end plate mounting hole 101 is screwed into the connecting bar small diameter portion 102b, and the head 100a seat on the stepped bolt 100 is secured. When the surface 100c comes into contact with the end plate connecting surface 101c, the second bolt insertion step is completed.

  In the stepped bolt 100 used in the stepped bolt insertion step S5, the length L of the base shaft portion 10A is such that the length L1 in the A direction of the end plate large diameter portion 101a as shown in FIG. Is longer than the total length L4 (L> L4 = L1 + L2). Further, as shown in FIG. 6, the length L1 of the end plate small diameter portion 101b and the length L2 of the connecting bar large diameter portion 102a are added together. The length is shorter than the length L3 (L <L3).

  In such a stepped bolt 100, the base shaft portion 10A has an end in the state where there is a gap S1 in the A direction between the first end plate 81 and the connecting bars 83 and 84 in the second bolt insertion step shown in FIG. The plate mounting hole 101 and the connecting bar mounting hole 102 are located across the A direction. At this time, the stepped bolt 100 is formed in the end plate mounting hole 101 and the connecting bar mounting hole with a gap S2 in the A direction between the step surface 10C of the base shaft portion 10A and the connecting bar connecting surface 102c. 102.

14 and 15 are process diagrams for explaining a method for manufacturing the fuel cell stack 1 (sitting process S6).
In the seating step S6 shown in FIG. 14, similarly to the compression step S2 described above, the pressing member 152 (see FIG. 9) is lowered to bring the second end plate 82 and the connecting bars 83 and 84 into contact with each other as shown in FIG. In the A direction. At that time, the second end plate 82 moves while being guided by the base shaft portion 10 </ b> A of the stepped bolt 100. Specifically, the second end plate 82 descends while the inner peripheral surface of the end plate small-diameter portion 101 b is in sliding contact with the outer peripheral surface of the base shaft portion 10 </ b> A of the stepped bolt 100, and contacts the connecting bars 83 and 84. At this time, the movement of the second end plate 82 in the direction crossing the A direction is restricted by the base shaft portion 10 </ b> A of the stepped bolt 100, and the second end plate 82 is not displaced with respect to the connecting bars 83 and 84. Moving.

FIG. 16 is a process diagram for explaining a method of manufacturing the fuel cell stack 1.
As shown in FIG. 16, after the seating step S6, the second end plate 82 and the connecting bars 83, 84 are fastened. Specifically, the stepped bolt 100 inserted in the stepped bolt insertion step S5 is tightened to a position where the stepped surface 10C in the A direction is close to the connecting bar connecting surface 102c with a gap therebetween. The two end plates 82 and the first connection bar 83, and the second end plates 82 and the second connection bar 84 are fastened by the stepped bolts 100, respectively.
The first end plate 81 and the connection bars 83 and 84 may be fastened after the seating step S6.

  Next, the compressive load applied to the laminate 160 from the laminator 150 is released. Thereafter, the side panel 80 is assembled to the laminate 160 to complete the fuel cell stack 1 described above.

  Thus, in this embodiment, it was set as the structure which uses the stepped volt | bolt 100 for fastening with the end plates 81 and 82 and each connection bar 83 and 84. FIG. In the bolt insertion step S5 prior to the seating step S6, the second end plate 82 and the connecting bars 83, 84 are in a separated state. However, the stepped bolt 100 of this embodiment has a gap between them. A base shaft portion 10A having a length L corresponding to S is provided. As described above, in this embodiment, the dimension of the base shaft portion 10A of the stepped bolt 100 is longer than the length L4 obtained by adding the length L1 in the A direction of the end plate large diameter portion 101a and the gap S1 described above. Furthermore, the length L1 of the end plate small diameter portion 101b and the length L2 of the connecting bar large diameter portion 102a are set to a length L3 or less. For this reason, in the bolt insertion step S5, when the stepped bolt 100 is inserted in a state where the second end plate 82 and the connection bars 83 and 84 are separated from each other, the tip end side of the stepped bolt 100 is connected to the connection bar mounting hole 102. Without dropping off, the stepped bolt 100 can be inserted so that the base shaft portion 10A is positioned across the end plate attachment hole 101 and the connecting bar attachment hole 102 in the A direction.

  In this way, by arranging the base shaft portion 10A of the stepped bolt 100 in the end plate mounting hole 101 and the connecting bar mounting hole 102 at the time of the bolt insertion step S5, the second seating step S6 is performed in the second seating step S6. When the end plate 82 and the connecting bars 83 and 84 are contacted in the A direction, the second end plate 82 can be moved using the base shaft portion 10A of the stepped bolt 100 as a guide. Thereby, the position shift of the second end plate 82 with respect to the connecting bars 83 and 84 is less likely to occur, so that the assembly can be performed with high accuracy and workability is improved.

  Further, in the present embodiment, in the bolt insertion step S5, at least a part of the male screw portion 10B of the stepped bolt 100 is screwed to the connecting bar small diameter portion 102b, and the outer peripheral surface of the base shaft portion 10A is the end plate small diameter portion 101b. And the inner peripheral surface of both of the connecting bar large diameter portions 102a. Since the stepped bolts 100 are temporarily fixed to the second end plate 82 and the connecting bars 83, 84, the stepped bolts 100 are removed or radially (direction A) when the seating step S6 is performed. Wobble in the horizontal direction intersecting For this reason, the displacement between the second end plate 82 and the connection bars 83 and 84 is further prevented, and the second end plate 82 is smoothly directed toward the connection bars 83 and 84 along the base shaft portion 10A of the stepped bolt 100. Can be moved. Thus, the seating step S6 can be performed in a stable state using the stepped bolt 100 as a guide.

  Further, in the present embodiment, a stepped bolt 100 in which the base shaft portion 10A and the male screw portion 10B are integrally formed is used as the fastening member, and the male screw portion 10B is screwed into the connecting bar small diameter portion 102b, and the base shaft portion. 10A is in close contact with the inner peripheral surface of both the end plate small diameter portion 101b and the connecting bar large diameter portion 102a. For this reason, it can suppress that the reactive gas which leaked from the cell laminated body 3 flows between the end plate attachment hole 101 and the connection bar attachment hole 102, and the stepped volt | bolt 100, and flows to the outer side of A direction. .

  In the present embodiment, the base shaft portion 10 </ b> A of the stepped bolt 100 receives a shear load acting between the end plates 81 and 83 and the connection bars 83 and 84. As a result, the conventionally used cylindrical knock becomes unnecessary and the number of assembling steps can be reduced, so that the cost for the production line can be reduced.

  As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to. You may combine the structure of each embodiment suitably.

  For example, in the above-described embodiment, in the bolt insertion step S5, at least a part of the male screw portion 10B of the stepped bolt 100 is screwed to the connecting bar small diameter portion 102b, but the base shaft portion 10A of the stepped bolt 100 is the end. As long as they are arranged in the plate attachment hole 101 and the connection bar attachment hole 102, the male screw portion 10B does not necessarily have to be screwed to the connection bar small diameter portion 102b. Even in this case, since the outer peripheral surface of the base shaft portion 10A is in contact with the inner peripheral surfaces of the end plate mounting hole 101 and the connecting bar mounting hole 102, rattling of the stepped bolt 100 in the radial direction is suppressed. The seating step S6 can be carried out in the state where it is in the closed state.

  For example, depending on the shape of the end plates 81 and 82, the length L of the base shaft portion 10A of the stepped bolt 100 can be appropriately changed. As shown in FIGS. 17A and 17B, when the end plates 81 and 82 are not provided with counterbore (end plate large diameter portion 101a), the length of the end plate mounting hole 103 in the A direction is as follows. The length L5 in the A direction of the end plate mounting hole 103 that is longer than the total length of L1 and the above-described gap S1 (FIG. 17A) and has a constant diameter in the thickness direction of the end plates 81 and 82. And the length obtained by adding the length L2 of the connecting bar large diameter portion 102a in the A direction is approximately the same as or shorter than that (FIG. 17B). Thereby, the same effect as embodiment mentioned above can be acquired.

  Moreover, although this embodiment described the example using the stepped volt | bolt 100 which has the base shaft part 10A and the external thread part 19B from which a diameter mutually differs, it does not restrict to this. For example, the fastening member of the present invention has a so-called normal hexagon bolt in which the cylindrical portion and the screw portion have substantially the same diameter, and a ring member separate from this, and the ring member is press-fitted into the cylindrical portion of the hexagon bolt. You may use the fastening member formed by exterior. In this case, the portion where the ring member is extrapolated to the cylindrical portion of the hexagon bolt corresponds to the base shaft portion 10A of the stepped bolt 100 described above, and the screw portion of the hexagon bolt corresponds to the male screw portion 10B of the stepped bolt 100 described above. Set to the specified dimension. The hexagon bolt and the ring member are assembled in advance before the bolt insertion step S5 and prepared as one fastening member. The bolts used are not limited to hexagon bolts.

  In addition, for example, in order to improve the gas sealing performance by the stepped bolt 100, a housing groove is formed on the outer peripheral surface of the base shaft portion 10 </ b> A of the stepped bolt 100 described above, and the seal member is housed in the housing groove. Also good. At this time, it is preferable to use a sealing member having an annular shape with the A direction as the axial direction and formed of an elastically deformable material (for example, an O-ring or the like).

DESCRIPTION OF SYMBOLS 1 ... Fuel cell stack 2 ... Unit cell (fuel cell)
3 ... Cell stack 10A ... Base shaft (positioning part)
10B ... Male screw part (screw part)
10C ... Step surface 81 ... First end plate 82 ... Second end plate 83, 84 ... Connection bar (connection member)
100: Stepped bolt (fastening member)
100b ... Shaft 101 ... End plate mounting hole 102 ... Connecting bar mounting hole (connecting member mounting hole)
160 ... Laminated body A direction ... first direction L, L1, L2, L3, L4 ... length S1 ... gap

Claims (4)

A first end plate, a cell stack in which a plurality of fuel cells are stacked in a first direction, and a step of stacking a second end plate in this order in the first direction;
A connecting member arranging step of arranging a connecting member between the first end plate and the second end plate;
A fastening member is inserted into the end plate mounting hole and the connecting member mounting hole in a state where there is a gap in the first direction between one of the first end plate and the second end plate and the connecting member. A fastening member insertion step;
A seating step of moving the first end plate and the second end plate closer in the first direction and abutting the one end plate and the connecting member in the first direction;
A fastening step of fastening the one end plate and the connecting member in the first direction by the fastening member;
The fastening member has a positioning portion for guiding the first end plate, the second end plate, and the connecting member to move in the first direction in the seating step;
In the fastening member insertion step, the fastening member is inserted so that the positioning portion is positioned across the first plate in the end plate attachment hole and the connection member attachment hole.
A method of manufacturing a fuel cell stack characterized by the above. The length of the positioning portion along the first direction is longer than a length obtained by adding the length along the first direction of the end plate mounting hole and the gap in the first direction. It is below the length which added each length along the said 1st direction of a hole and the said connection member attachment hole,
The method for producing a fuel cell stack according to claim 1. The fastening member includes the positioning portion and a screw portion provided on a distal end side of the positioning portion;
In the fastening member inserting step, a part of the screw portion is screwed into the connecting member mounting hole.
The method for producing a fuel cell stack according to claim 1 or 2, wherein In the fastening member insertion step,
Using the fastening member in which the positioning portion and the screw portion having a smaller diameter than the positioning portion are integrally formed,
The method for producing a fuel cell stack according to claim 3.

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