JP2006049221A - Fuel cell fastening structure and fastening method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To equalize bearing pressure for pressing an electrolyte membrane between separators. <P>SOLUTION: When a belt 25 for fastening a fuel cell stack 1 is extended by thermal expansion of separators catching the electrolyte membrane or swelling thereof due to water inclusion of the electrolyte membrane itself, a plate spring 21 between a pressing plate 19 and an end plate 13 is extended to the pressing plate 19 in a direction separating it from the end plate 13. The lower end of the plate spring 21 is fixed to the end plate 13 and an engagement projection 21a at its upper end is relatively moved along a cam groove 43a formed on the circumferential surface of a winding shaft 43, whereby the winding shaft 43 is rotated. A take-up reel 35 is connected to the winding shaft 43 through a detachable spline ring 45, and a wire 31 with an end of the belt 25 connected thereto is connected to the take-up reel 35. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a fuel cell fastening structure in which an electrolyte membrane having electrodes on both sides is sandwiched between a pair of separators to constitute a unit cell, and a fuel cell stack formed by laminating a plurality of unit cells is fastened and fixed in the laminating direction. And a fastening method.

As a conventional fuel cell fastening structure, the fuel cell stack is surrounded by a belt-like fastening member along the stacking direction, and the fuel cell stack is fastened and fixed in the stacking direction at three points by fastening bolts of different diameters. Is described in Patent Document 1 below.
JP 2001-135343 A

  By the way, in the fuel cell fastening structure that fastens and fixes the fuel cell stack, the fastening member always supports the fastening load, and also swells due to the thermal expansion of the separator sandwiching the electrolyte membrane and the moisture content of the electrolyte membrane itself. Therefore, it expands and contracts in the stacking direction and receives repeated stress. For this reason, permanent deformation occurs in the fastening member (for example, when a metal belt is used as the fastening member, permanent deformation occurs due to metal fatigue), and there is a high possibility that the fastening member will stretch. The surface pressure that presses the electrolyte membrane between the separators becomes non-uniform, resulting in uneven performance between the unit cells, poor sealing, and, if the degree is severe, the reaction surface is concentrated locally, resulting in fuel The performance of the fuel cell is lowered, for example, causing deterioration of the battery.

  Therefore, an object of the present invention is to make uniform the surface pressure for pressing the electrolyte membrane between the separators.

  The present invention provides a fuel cell fastening structure in which an electrolyte membrane having electrodes on both sides is sandwiched between a pair of separators to constitute a unit cell, and a fuel cell stack formed by laminating a plurality of unit cells is fastened and fixed in the laminating direction. In the fuel cell stack, the fuel cell stack is provided with a tightening force adjusting mechanism that converts an extension amount in the stacking direction of the stack components such as the electrolyte membrane and the separator into a tightening force in the stacking direction of the fuel cell stack. Main features.

  According to the present invention, the tightening force adjusting mechanism converts the extension amount in the stacking direction of the stack components such as the electrolyte membrane and the separator in the fuel cell stack into the tightening force in the stacking direction of the fuel cell stack. Even if the components extend in the stacking direction, the initial tightening load can be maintained, the surface pressure for pressing the electrolyte membrane between the separators can be made uniform, and the performance degradation of the fuel cell can be avoided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a fuel cell stack 1 having a fuel cell fastening structure according to a first embodiment of the present invention, and FIG. 2 is a plan view thereof. Although the fuel cell stack 1 is not particularly shown in detail, a unit cell is configured by sandwiching a solid polymer electrolyte membrane having electrodes composed of a catalyst layer and a gas diffusion layer on both sides with a pair of separators. A battery stack 3 in which a plurality of batteries are stacked in the vertical direction in FIG. 1 is provided. Current collecting plates 5 and 7, insulating plates 9 and 11, and end plates 13 and 15 are arranged on both sides (upper and lower sides in FIG. 1) of the battery stack 3.

  Further, in the upper part of the end plate 13 on the upper side in FIG. 1, the extension amount in the stacking direction of the stack components such as the electrolyte membrane and the separator in the fuel cell stack 1 is tightened in the stacking direction of the fuel cell stack 1. A main part of the tightening force adjusting mechanism 17 for converting to an applied force is provided. The tightening force adjusting mechanism 17 will be described below.

  A pressing plate 19 is arranged on the outer side of the end plate 13, and a disc spring 21 as an elastic body is interposed between the pressing plate 19 and the end plate 11. A belt fixing portion 23 is provided on the right end of the pressing plate 19 in FIG. 1, and one end of a metal belt 25 as a belt-like member wound around the outer periphery of the fuel cell stack 1 is fixed to the belt fixing portion 23. To do. The belt 25 has a width dimension of about one third of the vertical dimension in FIG. 2 of the fuel cell stack 1 and is disposed at the center position in the width direction of the fuel cell stack 1. Needless to say, the width and number of the belts 25 change depending on the shape of the fuel cell itself.

  The belt 25 described above extends downward along the stacking direction from the belt fixing portion 23, winds so as to cover the lower end plate 15, and then extends upward along the stacking direction. The end is connected to the belt connecting portion 29 through a semicircular arc guide portion 27 formed on the pressing plate 19.

  One end of the wire 31 is connected to the central position of the belt connecting portion 29, and the other end of the wire 31 is connected to the take-up reel 35 via the guide pulley 33 on the way. The take-up reel 35 is rotatably installed on the central portion of the pressing plate 19 and rotates in the clockwise direction in FIG. 2 to wind up the wire 31 and fasten the belt 25.

  Further, the take-up reel 35 includes a ratchet blade 37 on the outer periphery of a cylindrical portion formed in the lower portion thereof, as shown in FIG. 2, and a ratchet claw 39 is engaged with the ratchet blade 37. The ratchet claw 39 is rotatably connected to the rotation support pin 41 fixed to the pressing plate 19 at the base end portion thereof, and the claw portion 39a at the front end thereof is engaged with the ratchet blade 37 so that the drawing of the take-up reel 35 is achieved. 2 to restrict the counterclockwise rotation. That is, the take-up reel 35 includes a ratchet mechanism (a ratchet blade 37, a ratchet pawl 39) that restricts rotation in the rotational direction corresponding to the slack direction of the belt 25. There is a spring for pressing the ratchet pawl 39 against the ratchet blade 37 so that it does not come off due to the rotation of the shaft.

  A lower end of a winding shaft 43 extending in a direction orthogonal to the surface of the end plate 13 is rotatably connected to the center portion of the end plate 13. With the winding shaft 43, the pressing plate 19 and the disc spring 21, an end plate in which the extension amount of the belt 25 corresponding to the extension amount of the stack components in the stacking direction is arranged at both ends of the fuel cell stack 1. The compression part which converts into the compression force between 13 and 15 is comprised.

  The winding shaft 43 protrudes upward in FIG. 1 through through holes 19a and 35a formed in the pressing plate 19 and the winding reel 35, respectively. Further, as shown in detail in FIG. 3, a spiral cam groove 43 a is formed on the outer periphery of the winding shaft 43, and the cam groove 43 a is formed at the upper end portion of the disc spring 21 described above. The engaging protrusion 21a is movably engaged. The lower end of the disc spring 21 is fixed to the end plate 13.

  FIG. 4A is an enlarged front cross-sectional view showing the engagement protrusion 21 a of the disc spring 21, and FIG. 4B is a plan view showing only the upper end surface portion of the disc spring 21. According to this, a pair of engaging protrusions 21a are provided at positions facing each other on the inner peripheral edge on the upper side in FIG. 1, projecting inward as shown in FIG. 4 (b), and In FIG. 4A, it is bent downward.

  As shown in FIG. 1, the through-hole 35a of the take-up reel 35 is formed larger than the through-hole 19a of the pressing plate 19, and the inner surface of the through-hole 35a and the take-up shaft 43 are mutually connected. A spline ring 45 serving as a connector having a rotation restricting portion for restricting the rotation of the attachment is detachably attached.

  The spline ring 45 is inserted between the take-up reel 35 and the take-up shaft 43 as shown in FIG. 5A as a plan view and as shown in FIG. And a flange portion 45b formed at the upper end of the cylindrical portion 45a in FIG. And the inner peripheral spline part 45c as a rotation control part is formed in the inner peripheral surface of the cylindrical part 45a and the flange part 45b, and the outer periphery spline part 45d as a rotation control part is formed in the outer periphery of the cylindrical part 45a, respectively. The inner peripheral spline portion 45 c engages with a take-up shaft spline portion 43 b formed on the outer periphery of the take-up shaft 43, and the outer peripheral spline portion 45 d is a take-up reel spline portion 35 b formed in the through hole 35 a of the take-up reel 35. Engage with. By these engagements, mutual rotation between the take-up reel 35 and the take-up shaft 43 is restricted.

  Next, the operation will be described.

  When the tightening load is first applied to the fuel cell stack 1, the pressing plate 19 is pressed using a hydraulic device (not shown) with the spline ring 45 removed, and the wire 31 is loosened in this state. The belt 25 is tightened by winding it on the take-up reel 35 until there is no more. When winding the wire 31, the take-up reel 35 is rotated in the clockwise direction in FIG. 2. At this time, the ratchet mechanism rotates the take-up reel 35 in the counterclockwise direction, that is, the direction in which the belt 25 is slackened. Rotation is regulated. The work of rotating the take-up reel 35 is performed using a tool (not shown).

  Thereafter, the spline ring 45 is engaged with the inner peripheral spline part 45c of the take-up shaft 43 and the outer peripheral spline part 45d of the take-up reel 35 and 35b, respectively. They are inserted between the take-up shaft 43 and the take-up reel 35 to connect them.

  In the state where the fuel cell stack 1 is fastened and fixed in this manner, the fuel cell stack 1 expands and contracts in the stacking direction due to thermal expansion of the separator sandwiching the electrolyte membrane and swelling due to water content of the electrolyte membrane itself. When the belt 25 extends, the pressing plate 19 is pushed by the disc spring 21 and moves away from the end plate 13.

  With the movement of the pressing plate 19, the disc spring 21 is extended, and with this extension, the engaging projection 21 a of the disc spring 21 moves relative to the cam groove 43 a of the winding shaft 43. The winding shaft 43 rotates in the clockwise direction in FIG. By winding the wire 31, the amount of elongation of the belt 25 described above can be absorbed, and the tightening load initially applied to the fuel cell stack 1 can be maintained. That is, the amount of extension in the stacking direction of the stack components such as the electrolyte membrane and separator in the fuel cell stack 1 is converted into the tightening force in the stacking direction of the fuel cell stack 1 by the tightening force adjusting mechanism 17. Note that the upper portion of the disc spring 21 is restricted from rotating by, for example, a protrusion provided on the upper surface of the disc spring 21 being fitted in a hole on the pressing plate 19 side.

  Since the rotation of the winding shaft 43 in the counter-winding direction (counterclockwise in FIG. 2) is restricted by the ratchet mechanism, the winding shaft 43 basically does not move in the direction of loosening the wire 31 from the initial position. It is fixed at the position where it was taken. Actually, when the elongation of the belt 25 (wire 31) and the winding force are balanced, the winding shaft 43 stops rotating.

  According to the fuel cell fastening structure of the first embodiment described above, the take-up shaft 43 that winds up the wire 31 rotates according to the extension of the belt 25 caused by the expansion and contraction of the fuel cell stack 1, and the belt 25 is further rotated. Since it operates in the tightening direction, the initial tightening load on the fuel cell stack 1 can be maintained, the surface pressure for pressing the electrolyte membrane between the separators is made uniform, the performance variation between unit cells, the seal failure, By concentrating the reaction surface locally, it is possible to prevent the deterioration of the fuel cell and to avoid the performance deterioration of the fuel cell.

  In addition, since the fuel cell fastening structure described above is mechanically configured and operates without power, it is possible to save power in the fuel cell system and contribute to efficiency improvement.

  When the fuel cell stack 1 is assembled, the pressing plate 19 is pressed with the spline ring 45 removed, and then the wire 31 is taken up by the take-up reel 35, and then the spline ring 45 is attached to fix the take-up reel 35. Therefore, the winding operation of the wire 31 by the take-up reel 35 is easy, and when the disc spring 21 is assembled, the lower end thereof can be fixed to the end plate 13 from the beginning, and the assembly workability is improved. improves.

  FIG. 6 is a cross-sectional view of the main part of the fuel cell stack 1 provided with the fuel cell fastening structure according to the second embodiment of the present invention, and FIG. 7 is a plan view thereof. In addition, the same code | symbol is attached | subjected to the same component as FIG.1 and FIG.2 which shows 1st Embodiment.

  In this embodiment, a worm 47 protruding upward in FIG. 6 from the pressing plate 19 is provided at the end of the winding shaft 43 opposite to the end plate 13, and the worm gear 49 is engaged with the worm 47. The worm gear 49 is attached to a second winding shaft 51 extending in a direction orthogonal to the paper surface in FIG. 6 via a spline ring 53 as a connecting tool.

  As with the spline ring 45 shown in FIG. 5, the spline ring 53 is provided with an inner peripheral spline portion 53a and an outer peripheral spline portion 53b as rotation restricting portions on the inner peripheral surface and the outer peripheral surface formed in a cylindrical shape. These spline portions 53 a and 53 b are engaged with a take-up shaft spline portion 51 a formed on the second take-up shaft 51 and a gear spline portion 49 a formed on the inner peripheral surface of the worm gear 49, respectively.

  The above-described spline ring 53 can be released from the respective engagement states described above by sliding in the axial direction, thereby disconnecting the connection state between the worm gear 49 and the second winding shaft 51. it can.

  The second winding shaft 51 is rotatably supported at both ends in the axial direction on the pressing plate 19 via mounting brackets 55, 57, and at two locations between the mounting brackets 55, 57 and the worm gear 49. The end of the belt 25 is fixed.

  Further, the base end portion of the ratchet claw 59 is rotatably supported on the side surface of the one mounting bracket 55 via the rotation support pin 61. By engaging the claw 59a portion at the tip of the ratchet claw 59 with a ratchet blade 51b formed on the outer peripheral surface of the second winding shaft 51 protruding sideward (upward in FIG. 7) from the mounting bracket 55. The rotation of the second winding shaft 51 in the counterclockwise direction in FIG. 6 is restricted. That is, the second winding shaft 51 includes a ratchet mechanism that restricts rotation in the rotational direction corresponding to the slack direction of the belt 25. There is a spring for pressing the ratchet pawl 59 against the ratchet blade 51b so that it does not come off due to the rotation of the shaft.

  Also in the second embodiment, when the tightening load is first applied to the fuel cell stack 1, the pressing plate 19 is pressed using a hydraulic device (not shown) with the spline ring 53 removed. Then, the belt 25 is wound around the second winding shaft 51 until the belt 25 is not loosened, and the belt 25 is tightened. Thereafter, the spline ring 53 is fitted between the worm gear 49 and the second winding shaft 51, and both are connected.

  With the fuel cell stack 1 fastened and fixed in this way, the fuel cell stack 1 expands and contracts in the stacking direction due to thermal expansion of the separator sandwiching the electrolyte membrane and swelling due to water content of the electrolyte membrane itself, and the belt 25 When extended, the pressing plate 19 is pushed by the disc spring 21 and moves away from the end plate 13 as in the first embodiment.

  The disc spring 21 extends along with the movement of the pressing plate 19, and the engagement projection 21 a of the disc spring 21 relatively moves along the cam groove 43 a of the winding shaft 43 along with the extension. This relative movement causes the winding shaft 43 to rotate in the clockwise direction in FIG. 7 together with the worm 47, and the worm gear 49 and the second winding shaft 51 rotate in the clockwise direction in FIG. The belt 25 is wound up. By winding up the belt 25, the amount of elongation can be absorbed, and the tightening load initially applied to the fuel cell stack 1 can be maintained, and the same effect as in the first embodiment can be obtained.

  In the second embodiment, the rotation direction of the second winding shaft 51 is the same as the winding direction of the belt 25 tightening the fuel cell stack 1, and therefore the belt 25 can be directly wound. The wire 31 as used in the first embodiment is not necessary. Of course, wires can also be used.

  Further, if the diameter and the number of teeth of the worm gear 49 are appropriately selected, the torque required to rotate the winding shaft 43 can be reduced. Therefore, the diameter of the winding shaft 43 is reduced and the axial length is shortened. Small size is possible.

  Furthermore, since the worm gear 49 of the second winding shaft 51 is coupled to the second winding shaft 51 via a detachable spline ring 53, the spline ring 53 is mounted as in the first embodiment. The belt 25 can be wound up in the removed state, and workability is improved.

  According to the present invention, the tightening force adjusting mechanism includes a belt-like member wound around the outer periphery of the fuel cell stack along the stacking direction of the fuel cell stack, and an extension amount of the stack component in the stacking direction. The expansion amount of the corresponding band-shaped member is constituted by a compression part that converts the compression force between the end plates arranged at both ends in the stacking direction of the fuel cell stack, so that the thermal expansion of the separator sandwiching the electrolyte membrane, and the electrolyte Even if the fuel cell stack expands and contracts in the stacking direction due to swelling due to the water content of the membrane itself, and the belt-like member extends, the amount of extension of the belt-like member is the first in the fuel cell stack because the compression part absorbs it. The tightening load applied to can be maintained.

  The compression portion is positioned on the outer side in the stacking direction of one end plate and fixes one end of the band-shaped member, and is rotatably attached to the one end plate and connects the other end of the band-shaped member. A winding shaft that winds the belt-shaped member, and is interposed between the end plate and the pressing plate, and rotates the winding shaft so as to wind up the amount of elongation as the belt-shaped member extends. Since each of the elastic bodies is provided, a pressing plate is used when the fuel cell stack expands and contracts in the stacking direction due to the thermal expansion of the separator sandwiching the electrolyte membrane or the swelling caused by the water content of the electrolyte membrane itself, and the belt-like member extends. Is pushed by the elastic body and moves away from the end plate, and along with the expansion of the elastic body at this time, the winding shaft is rotated to wind up the belt-like member. The fastening load appended to the first can be maintained for click.

  The other end of the belt-like member is connected to a take-up reel via a wire, and a connecting tool having a rotation restricting portion for restricting the mutual rotation between the take-up reel and the take-up shaft is attached and detached. Since the take-up reel is equipped with a ratchet mechanism that restricts rotation in the rotational direction corresponding to the slack direction of the belt-like member, the coupling tool is pressed while pressing the pressing plate when assembling the fuel cell stack. The strip-shaped member can be taken up by the take-up reel in a state in which is removed, and assembling workability is improved.

  A worm is provided at the end of the winding shaft opposite to the end plate, and a second winding shaft for winding the belt-like member by connecting the other end of the belt-like member to a worm gear screwed into the worm. Connected and detachably connected to the second winding shaft and the worm gear is a connecting tool having a rotation restricting portion that restricts the mutual rotation between the two winding shafts. Since the ratchet mechanism for restricting the rotation in the rotational direction corresponding to the slack direction of the belt-like member is provided, the second winding shaft is in a state in which the connector is removed while pressing the pressing plate when assembling the fuel cell stack. As a result, the belt-shaped member can be wound up, and the assembly workability is improved.

  The elastic body is constituted by a disc spring, and the end of the disc spring on the pressing plate side is fitted in a spiral cam groove formed on the outer peripheral surface of the winding shaft so as to be relatively movable. The winding shaft can be easily and reliably rotated corresponding to the elongation.

  In the fuel cell fastening method, a unit cell is configured by sandwiching an electrolyte membrane having electrodes on both sides with a pair of separators, and a fuel cell stack formed by stacking a plurality of unit cells is fastened and fixed in the stacking direction. The stack component such as the electrolyte membrane and separator in the battery stack is converted into the stacking direction tightening force of the fuel cell stack by the tightening force adjusting mechanism, so that the stack component is stacked in the stacking direction. Even if it extends, the initial tightening load can be maintained, the surface pressure for pressing the electrolyte membrane between the separators can be made uniform, and the performance degradation of the fuel cell can be avoided.

It is sectional drawing of the fuel cell stack provided with the fuel cell fastening structure concerning the 1st Embodiment of this invention. It is a top view of the fuel cell stack in a 1st embodiment. It is a front view of the winding axis | shaft in 1st Embodiment. (A) is a fragmentary sectional view which shows the engagement protrusion of the disc spring in 1st Embodiment, (b) is a top view of the upper end surface part of a disc spring. (A) is a top view of the spline ring in 1st Embodiment, (b) is AA sectional drawing of (a). It is sectional drawing of the principal part of the fuel cell stack provided with the fuel cell fastening structure concerning the 2nd Embodiment of this invention. It is a top view of the fuel cell stack in a 2nd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell stack 13, 15 End plate 17 Tightening force adjustment mechanism 19 Pressing plate (compression part)
21 Belleville spring (elastic body, compression part)
25 Belt (band-like member)
31 wire 35 take-up reel 37, 51b ratchet blade (ratchet mechanism)
39,59 Ratchet claw (Ratchet mechanism)
43 Winding shaft (compression part)
43a Spiral cam groove 45, 53 Spline ring (connector)
45c, 53a Inner peripheral spline part (rotation restricting part)
45d, 53b Outer peripheral spline part (rotation restricting part)

Claims (7)

  In a fuel cell fastening structure in which an electrolyte membrane having electrodes on both sides is sandwiched between a pair of separators to form a unit cell, and a fuel cell stack formed by laminating a plurality of unit cells is fastened and fixed in the stacking direction. A fuel cell comprising: a tightening force adjusting mechanism for converting an extension amount in the stacking direction of the stack components such as the electrolyte membrane and separator in the battery stack into a tightening force in the stacking direction of the fuel cell stack. tightening structure.   The tightening force adjusting mechanism includes: a belt-like member wound around an outer periphery of the fuel cell stack along the stacking direction of the fuel cell stack; and a belt-like member corresponding to an amount of extension of the stack component in the stacking direction. 2. The fuel cell fastening structure according to claim 1, wherein the fuel cell fastening structure is configured by a compressing portion that converts an extension amount into a compressive force between end plates disposed at both ends in the stacking direction of the fuel cell stack.   The compression portion is positioned on the outer side in the stacking direction of one end plate and fixes one end of the band-shaped member, and is rotatably attached to the one end plate and connects the other end of the band-shaped member. A winding shaft that winds the belt-shaped member, and is interposed between the end plate and the pressing plate, and rotates the winding shaft so as to wind up the amount of elongation as the belt-shaped member extends. The fuel cell fastening structure according to claim 2, further comprising an elastic body.   The other end of the belt-like member is connected to a take-up reel via a wire, and a connecting tool having a rotation restricting portion for restricting the mutual rotation between the take-up reel and the take-up shaft is attached and detached. 4. The fuel cell fastening structure according to claim 3, wherein the take-up reel is provided with a ratchet mechanism that restricts rotation in a rotational direction corresponding to a slack direction of the belt-shaped member.   A worm is provided at the end of the winding shaft opposite to the end plate, and a second winding shaft for winding the belt-like member by connecting the other end of the belt-like member to a worm gear screwed into the worm. Connected and detachably connected to the second winding shaft and the worm gear is a connecting tool having a rotation restricting portion that restricts the mutual rotation between the two winding shafts. The fuel cell fastening structure according to claim 3, further comprising a ratchet mechanism that regulates rotation in a rotation direction corresponding to a slack direction of the belt-shaped member.   The elastic body is constituted by a disc spring, and the end portion on the pressing plate side of the disc spring is fitted into a spiral cam groove formed on the outer peripheral surface of the winding shaft so as to be relatively movable. The fuel cell fastening structure according to any one of claims 3 to 5.   In the fuel cell fastening method, a unit cell is configured by sandwiching an electrolyte membrane having electrodes on both sides with a pair of separators, and a fuel cell stack formed by stacking a plurality of unit cells is fastened and fixed in the stacking direction. A fuel cell fastening characterized by converting the stacking direction elongation amount of the electrolyte membrane and separator in the battery stack into a stacking direction tightening force of the fuel cell stack by a tightening force adjusting mechanism. Method.

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