JP2006040716A - Fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reconcile conflicting functions of securing the flexural rigidity of an end plate and reducing a weight, without causing the extension of the outer diameter of the head part of a fastener and increase in the number of fastening points. <P>SOLUTION: A pair of electrodes are disposed on both sides of a solid polymer electrolyte membrane, a laminate is formed by laminating a plurality of unit cells formed by holding a pair of the electrodes between a pair of separators, and both ends of the laminate are held between a pair of the end plates. A pair of the end plates are mutually fastened and fixed by using an tension rod 11 provided with a shaft part 13 and a head part 15 positioned at the end part of the shaft part 13 while having an outer diameter larger than the shaft part 13. A reinforcement part 17 of a plate-like member to connect the shaft part 13 with the head part 15 is provided in the tension rod 11. Flexural rigidity of the head part 15 is increased by the reinforcement part 17, and deformation of the end plates are suppressed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell stack in which both ends of a stack of a plurality of unit cells are sandwiched between a pair of end plates, and the pair of end plates are fastened and fixed by a fastener.

  A polymer electrolyte fuel cell stack is configured by stacking a plurality of unit cells each having a pair of electrodes arranged on both sides of a polymer electrolyte membrane and sandwiching them between a pair of separators. The both ends of the plate are clamped and fixed by a pair of end plates.

Patent Document 1 listed below discloses a technique in which a pair of end plates is fastened with a pressurizing means and fastened with a fastening rod.
JP 2003-331906 A

  By the way, in order to improve the power generation performance and secure the gas sealing property, the pressure from the pressurizing means can be evenly applied to the electrodes and gas seals in the stack on the end plate that clamps and fixes the above laminate from both sides. Therefore, securing bending rigidity that suppresses displacement in the stacking direction, weight reduction for improving the output per unit weight of the fuel cell stack, and thickness reduction for reducing the size of the fuel cell stack are required.

  As described above, the end plate is required to satisfy both contradictory functions of an increase in weight associated with securing bending rigidity and a weight reduction associated with an increase in output and downsizing.

  However, since the conventional fuel cell stack requires the end plate itself to achieve the above-mentioned contradictory functions, both the securing of the bending rigidity of the end plate and the weight reduction for improving the output and miniaturization are required. It has become difficult to achieve.

  Further, when the rigidity of the end plate is supplemented by increasing the outer diameter of the head portion of the fastening rod or increasing the number of fastening points, problems such as an increase in weight due to an increase in the outer diameter or an increase in the number of parts, and deterioration in assemblability occur.

  Therefore, an object of the present invention is to achieve both contradictory functions of securing the bending rigidity and weight reduction of the end plate without increasing the outer diameter of the head portion of the fastener and increasing the number of fastening points.

  In the present invention, a pair of electrodes is arranged on both sides of a solid polymer electrolyte membrane, a plurality of unit cells each configured by sandwiching them between a pair of separators are stacked to form a stacked body, and both ends of the stacked body are paired with a pair. A fuel cell stack that is sandwiched between end plates, and is fastened and fixed between a pair of end plates with fasteners each having a shaft portion and a head portion having an outer diameter larger than that of the shaft portion. The most important feature is that the fastener is provided with a reinforcing portion that increases bending rigidity in a direction away from the end plate of the head portion.

  According to the present invention, the fastener that fastens and fixes the pair of end plates is provided with the reinforcing portion that increases the bending rigidity of the head portion, so that the reinforcing portion suppresses the displacement of the end plate, The rigidity of the end plate can be supplemented without increasing the outer diameter of the head part or increasing the number of fastening points, and therefore, it is possible to achieve both contradictory functions of ensuring the bending rigidity of the end plate and reducing the weight.

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

  First, the basic configuration and operation of a part that is common or similar across all the embodiments of the present invention will be described with reference to FIG. The fuel cell according to the present invention is a solid polymer electrolyte fuel cell (hereinafter simply referred to as a fuel cell), and is mounted on, for example, a fuel cell vehicle. However, you may use other than a motor vehicle.

  FIG. 1 is a perspective view showing the entire fuel cell stack. In this fuel cell stack, a stack 3 is formed by stacking a plurality of unit cells 1 that generate an electromotive voltage of about 1V. Each of the plurality of unit cells 1 constituting the stacked body 3 functions as a fuel cell. At both ends of the stack 3 in the stacking direction, current collector plates 5, insulating plates 7, and end plates 9 are arranged in this order, thereby constituting a fuel cell stack.

  The fuel cell stack is fastened using tension rods 11 arranged at the four corners and penetrating through the inside. Here, the number of tension rods 11 is not limited to four (four corners), and is not limited as long as the specification can secure a desired fastening force.

  The current collector plate 5 is formed of a gas impermeable conductive member such as dense carbon or copper plate, and the insulating plate 7 is formed of an insulating member such as rubber or resin. The end plate 9 is formed of a material having rigidity, for example, a metal material such as steel. The two current collector plates 5 are each provided with an output terminal 5a, and the electromotive force generated in the fuel cell stack is output via the output terminal 5a.

  Note that the above-described method of fastening the fuel cell stack does not require the tension rod 11 to pass through the inside of the stacked body 3, and the end plate 9 protrudes outward from the outer peripheral edge of the stacked body 3. The plates 9 may be formed larger and the end plates 9 protruding outward may be fastened together.

(First embodiment)
FIG. 2 shows a tension rod 11 according to the first embodiment of the present invention. 2A is a front view of the tension rod 11, and FIG. 2B is a bottom view of FIG. 2A.

  The tension rod 11 is positioned at an end portion of the shaft portion 13 and a shaft portion 13 inserted into a through-hole penetrating the laminated body 3, the current collector plate 5, the insulating plate 7 and the end plate 9 shown in FIG. Then, a head portion 15 having a diameter larger than that of the shaft portion 13 and transmitting a fastening load to one end plate 9, and a reinforcing portion 17 made of a triangular plate-like member connecting the shaft portion 13 and the head portion 15 are provided. Each has.

  A pair of reinforcing portions 17 are provided at positions facing each other with the shaft portion 13 interposed therebetween, the head portion joining end surface 17a is joined to the surface 15a facing the end plate 9 of the head portion 15, and the shaft portion joining end surface 17b is the shaft. The portion 13 is joined to the outer peripheral surface 13 a in the vicinity of the head portion 15. The reinforcing portion 17 may be integrated with the shaft portion 13 and the head portion 15 or may be attached to the shaft portion 13 and the head portion 15 later by welding or the like.

  A threaded portion 13b is formed at the end of the shaft portion 13 opposite to the head portion 15, and the threaded portion 13b is projected outward from the end plate 9 opposite to the head portion 15 shown in FIG. A nut (not shown) is screwed into the protruded screw portion 13b.

  This nut (not shown) constitutes a head portion having an outer diameter larger than that of the shaft portion 13, similarly to the head portion 15 described above. Therefore, the tension including the shaft portion 13, the head portion 15, and the reinforcing portion 17 described above. The rod 11 and the nut described above constitute a fastener having a shaft portion and a head portion having an outer diameter larger than that of the shaft portion located at the end of the shaft portion.

  The tension rod 11 described above is formed of a material having rigidity, for example, a metal material such as steel, and the surface is subjected to insulation treatment in order to prevent an electrical short circuit between the unit cells 1. Moreover, in the fastening section by the tension rod 11, for example, a load applying means such as spring steel may be interposed.

  Next, the principle of suppressing the displacement of the end plate 9 in this embodiment will be described.

  FIGS. 3A and 3B are diagrams for explaining the displacement operation when a predetermined load is applied to the fuel cell stack. FIG. 3A shows the deformation of the tension rod 11 accompanying the displacement of the end plate 9, and FIG. The displacement of the end plate 9 at P is shown. On the other hand, FIG. 4 is a displacement operation explanatory view similar to FIG. 3 in the case of using a conventional tension rod 110 that does not include the reinforcing portion 17 with respect to the tension rod 11 of the present embodiment.

  According to this, in contrast to the conventional tension rod 110, in the tension rod 11 of the present embodiment, the reinforcing portion 17 suppresses bending deformation in the direction away from the end plate 9 of the head portion 15 (θ1> θ2). As a result, as shown in FIG. 5, the maximum displacement δ of the end plate 9 can be reduced to δ2 (δ1> δ2) with respect to the conventional δ1.

  Next, an arrangement example of the tension rod 11 according to the first embodiment on the end plate 9 will be described with reference to FIG. The direction of the reinforcing portion 17 provided on the tension rod 11 is aligned with the direction in which the displacement of the end plate 9 indicated by the one-dot chain line in FIG. That is, the tension rod 11 is fastened so that the reinforcing portion 17 is positioned at a position that opposes the bending action of the end plate 11 in the stacking direction with the arrangement position of the tension rod 11 as a supporting point. Thereby, the bending deformation suppression effect of the head part 15 by the reinforcement part 17, and the displacement suppression effect of the end plate 9 by extension can be acquired.

  FIG. 6B shows a case where the position of the tension rod 11 is changed with respect to FIG. 7A shows an example in which a circular end plate 11A is used, and FIG. 7B shows an example in which a triangular end plate 11B is used. In either case, the direction of the reinforcing portion 17 of the tension rod 11 is aligned with the direction in which the displacement indicated by the one-dot chain line of the end plates 9, 9A, 9B is desired to be suppressed.

  Next, the positioning function of the tension rod 11 will be described with reference to FIG. 8A is an AA cross-sectional view of the end plate 9 and the tension rod 11 in FIG. 6, and FIG. 8B is a BB cross-sectional view of FIG.

  As shown in FIGS. 8A and 8B, the end plate 9 is provided with a groove 19 as a concave portion in which the reinforcing portion 17 enters and avoids interference with the end plate 9. As shown in FIG. 8B, the groove 19a has a width slightly larger than the thickness of the plate-like reinforcing portion 17, whereby the reinforcing portion 17 and the groove 19 are in a relationship between the key and the key groove. Positioning can be easily performed by eliminating the degree of freedom of rotation of the tension rod 11 with respect to the end plate 9. That is, the side surface 19a of the groove 19 serves as a rotation restricting portion that restricts the rotation of the tension rod 11 when the reinforcing portion 17 comes into contact with the screw portion 13b of a nut (not shown).

  Here, the groove 19a is formed so as to be aligned with the direction in which the displacement shown by the one-dot chain line shown in the end plates 9, 9A, 9B shown in FIGS. The end plate 9, 9A, 9B can be easily adjusted in the direction in which the displacement indicated by the one-dot chain line is desired to be suppressed.

  Further, since the reinforcing portion 17 enters the groove 19, the tension rod 11 can be prevented from coming into contact with the end plate 9 when fastened to the end plate 9, and the surface pressure distribution can be made uniform. .

  As shown in FIGS. 9 and 10, the number and position of the reinforcing portions 17 provided on the tension rod 11 can be freely set according to the direction in which the displacement of the end plate 9 is desired to be suppressed.

(Second Embodiment)
FIG. 11 shows a tension rod 11 according to the second embodiment of the present invention. FIG. 11A is a front view of the tension rod 11, and FIG. 11B is a bottom view of FIG. 11A. The tension rod 11 is provided with a tapered portion 21 that connects the shaft portion 13 and the head portion 15 in place of the plate-like reinforcing portion 17 in the tension rod 11 according to the first embodiment. The taper portion 21 has a conical shape that becomes narrower from the end plate facing surface of the head portion 15 toward the tip end side of the shaft portion 13, and is intentionally left when, for example, the tension rod 11 is manufactured by machining. Can be easily provided.

  Next, the fitting structure between the tension rod 11 and the end plate 9 in FIG. 11 will be described with reference to FIG. A concave tapered surface 23 is formed on the end plate 9 as a concave portion into which the tapered portion 21 of the tension rod 11 enters and contacts. As a result, when the tension rod 11 is fastened to the end plate 9, the contact area between the tension rod 11 and the end plate 9 increases to prevent the end plate 9 from coming into contact with each other, and the surface pressure distribution is made uniform. Can be planned. Moreover, since there is no restriction | limiting of the position of the rotation direction with respect to the end plate 9 of the tension rod 11, assembly property improves.

  13 and 14 show a modification of the tapered portion 21 shown in FIG. The tapered portion 21A in FIG. 13 is formed in a concave curved surface between the shaft portion 13 and the end portion on the outer peripheral side of the head portion 15. In this case, a concave portion into which the tapered portion 21A enters is provided on the end plate 9 side, and the inner surface shape of the concave portion is a convex curved surface corresponding to the concave curved surface of the tapered portion 21A. The entire surface of the convex curved surface may contact the concave curved surface of the tapered portion 21A, or a part along the concave curved surface may contact the entire circumference.

  On the other hand, the taper portion 21B of FIG. 14 has a surface 15b facing the end plate 9 on the outer peripheral side of the head portion 15 with the end portion 21Ba on the head portion 15 side being the center side from the outer peripheral side end portion of the head portion 15. Yes. In this case, a tapered concave portion into which the tapered portion 21B enters is provided in the end plate 9, and the tapered portion 21B is brought into contact with the entire surface in the concave portion or a part of the entire circumference along the inclination of the tapered portion, and the surface 15b is disposed on the end Contact the surface of the plate 9. Alternatively, the surface 15b may not be in contact with the end plate 9, and the tapered portion 21B may be brought into contact with the entire surface in the concave portion or a part of the entire circumference along the inclination of the tapered portion.

  As described above, the tapered portion 21 provided on the tension rod 11 may have any shape as long as it can assist the rigidity of the head portion 15.

(Third embodiment)
FIG. 15 shows a fastener according to the third embodiment of the present invention. This fastener uses the conventional tension rod 110 shown in FIG. 4, and the tension rod 11 in the second embodiment shown in FIG. 11 is attached to the nut 25 screwed into the threaded portion 13b of the tension rod 110. A tapered portion 27 similar to the tapered portion 21 is provided as a reinforcing portion. Corresponding to the tapered portion 27, the end plate 9 is provided with a tapered surface similar to the tapered surface 23 shown in FIG. Thereby, the displacement suppression effect can be exhibited also to the end plate 9 on the side where the nut 25 is provided.

  Instead of the tapered portion 27 of the nut 25 described above, a reinforcing portion made of a plate-like member as in the first embodiment shown in FIG. 2 may be provided.

  Moreover, the displacement suppression effect of the end plates 9 at both ends can be expected by combining the configuration in which the tension rod 11 is provided with the reinforcing portion and the configuration in which the nut 25 is provided with the reinforcing portion. However, in this case, when each reinforcing portion of the tension rod 11 and the nut 25 is a plate-like member as in the first embodiment shown in FIG. 2, one of the tension rod 11 and the nut 25 is used. It is necessary not to set a rotation restricting portion for the end plate 9 so that the reinforcing portion can rotate with respect to the end plate 9.

  According to the present invention, since the reinforcing portion connects the shaft portion and the head portion of the fastener, the fastener can easily have a function for suppressing the displacement of the end plate. .

  By configuring the reinforcing portion with a plate-like member, the plate-like member can supplement the rigidity of the end plate.

  By fastening the fastener so that the reinforcing portion is positioned at a position that opposes the bending action of the end plate in the stacking direction with the arrangement position of the fastener as a supporting point, the deformation of the end plate is further suppressed. I can expect.

  Since the concave portion into which the reinforcing portion enters the end plate is provided, it is possible to avoid interference between the reinforcing portion and the end plate, to prevent the fastener from hitting the end plate, and to uniform the surface pressure distribution. Can be planned.

  Since the concave portion includes a rotation restricting portion that abuts on the reinforcing portion and restricts the rotation of the fastener, the reinforcing portion can be positioned with respect to the end plate, and the direction of the reinforcing portion can be suppressed and the displacement of the end plate can be suppressed. It is possible to ensure a state that matches the desired direction, and to continuously maintain the deformation suppressing effect of the reinforcing portion on the end plate.

  Since the reinforcing portion includes a conical taper portion that narrows from the end plate facing surface of the head portion toward the tip end side of the shaft portion, the processing of the reinforcing portion can be easily performed at the time of production of a fastener. This is possible, and the position of the fastener in the rotational direction with respect to the end plate is not limited, so that the assemblability is improved.

  The end plate is provided with a concave portion into which the tapered portion enters, and the concave portion has a concave tapered surface with which the tapered portion comes into contact, so that a contact area between the fastener and the end plate is increased and the end of the fastener is increased. The contact with the plate can be prevented and the surface pressure distribution can be made uniform. Moreover, since there is no restriction | limiting of the position of the rotation direction with respect to the end plate of a fastener, assembly property improves.

  By making the head portion a nut that is screwed into a screw portion formed on the tip end side of the shaft portion, a displacement suppressing effect can be expected for the end plate on the side where the nut is provided.

It is a perspective view which shows the basic structure of the fuel cell stack of this invention. (A) is a front view of the tension rod concerning the 1st Embodiment of this invention, (b) is a bottom view of (a). FIG. 6 is an explanatory diagram of deformation operation when a predetermined load is applied to the fuel cell stack, where (a) shows deformation of the tension rod accompanying displacement of the end plate, and (b) shows displacement of the end plate near the tension rod. . FIG. 6 is a diagram illustrating a deformation operation when a predetermined load is applied to a conventional fuel cell stack, where (a) shows the deformation of the tension rod accompanying the displacement of the end plate, and (b) the displacement of the end plate near the tension rod. Indicates. It is explanatory drawing which shows the deformation | transformation suppression principle of an end plate. It is explanatory drawing which shows the example of arrangement | positioning on the end plate of the tension rod by 1st Embodiment. It is explanatory drawing which shows the example of arrangement | positioning on the end plate of the tension rod at the time of changing the shape of an end plate with respect to FIG. (A) is AA sectional drawing of FIG. 6, (b) is BB sectional drawing of FIG. (A) is a front view which shows the modification of the tension rod of FIG. 2, (b) is a bottom view of (a). It is explanatory drawing which shows the example of arrangement | positioning on the end plate by the tension rod of FIG. (A) is a front view of the tension rod concerning the 2nd Embodiment of this invention, (b) is a bottom view of (a). It is fitting structure figure of the tension rod and end plate in 2nd Embodiment. (A) is a front view which shows the modification of the tension rod of FIG. 11, (b) is a bottom view of (a). (A) is a front view which shows the other modification of the tension rod of FIG. 11, (b) is a bottom view of (a). It is a front view of the tension rod and nut concerning the 3rd Embodiment of this invention.

Explanation of symbols

1 unit cell 3 unit cell stack 9 end plate 11 tension rod (fastener)
13 Shaft portion 13b Screw portion 15 Head portion 17 Reinforcing portion made of plate-like member 19 Groove (concave portion)
19a Side surface of groove (rotation restricting part)
21, 21A, 21B, 27 Taper (Reinforcement)
23 Concave taper surface (concave)
25 Nut (fastener, head)

Claims (9)

  A pair of electrodes are arranged on both sides of the solid polymer electrolyte membrane, and a unit body is formed by laminating a plurality of unit cells that are sandwiched between a pair of separators, and both ends of the layered body are sandwiched between a pair of end plates. In the fuel cell stack in which the pair of end plates is fastened and fixed by a fastener having a shaft portion and a head portion having an outer diameter larger than that of the shaft portion. A fuel cell stack, characterized in that a reinforcing portion is provided on the tool to increase bending rigidity in a direction away from the end plate of the head portion.   2. The fuel cell stack according to claim 1, wherein the reinforcing portion connects a shaft portion and a head portion of the fastener. 3.   The fuel cell stack according to claim 2, wherein the reinforcing portion is formed of a plate-like member.   4. The fuel cell stack according to claim 1, wherein the reinforcing portion is positioned at a position that opposes the bending action of the end plate in the stacking direction with the arrangement position of the fastener as a support point. 5. A fuel cell stack, wherein the fastener is fastened.   5. The fuel cell stack according to claim 2, wherein the end plate is provided with a recess into which the reinforcing portion is inserted. 6.   6. The fuel cell stack according to claim 5, wherein the recess includes a rotation restricting portion that restricts rotation of the fastener by contacting the reinforcing portion.   3. The fuel cell stack according to claim 2, wherein the reinforcing portion includes a conical tapered portion that narrows from a surface facing the end plate of the head portion toward a tip side of the shaft portion. Fuel cell stack.   8. The fuel cell stack according to claim 7, wherein a concave portion into which the tapered portion enters the end plate is provided, and the concave portion has a concave tapered surface with which the tapered portion contacts. .   2. The fuel cell stack according to claim 1, wherein the head portion is a nut that is screwed into a screw portion formed on a distal end side of the shaft portion. 3.

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