JP4595318B2 - Fuel cell stack and tightening method thereof - Google Patents

Description

  The present invention relates to a fuel cell stack and a tightening method thereof.

  2. Description of the Related Art Conventionally, a cell pressurizing method has been proposed in which fuel cell components are stacked and assembled into a stack, and pressurization is performed so that the pressure distribution on the entire cell surface is uniform and the seal can be completely completed (see Patent Document 1).

In this case, a concave portion smaller than the outer dimension of the cell is provided on the inner surface of one end plate on the cell contact side, and pressurized water is introduced into the concave portion to pressurize the cell. In another embodiment, one end plate is vertically divided into two, and a two-part end plate is interposed between the end plate and the other end. The plate is fastened.
Japanese Patent Laid-Open No. 9-92323

  By the way, stacked fuel cell components are not necessarily uniform with variations in shape accuracy, and stacking multiple sheets will cause horizontal variations due to component accuracy variations, thickness variations such as seal adhesive, and assembly variations. Direction inclination etc. occur.

  When tightening a fuel cell stack assembled in a stacking state in which such a horizontal inclination occurs, there is a possibility that the pressure distribution over the entire cell surface cannot always be made uniform by the tightening method as shown in the conventional example. .

  Therefore, the present invention has been made in view of the above problems, and provides a fuel cell stack and a tightening method thereof that can make the pressure distribution on the entire cell surface uniform even in an assembled state in which a horizontal inclination or the like has occurred. With the goal.

  The present invention is a fuel cell stack in which fuel cell components are stacked so as to form a plurality of cells between upper and lower end plates, and the upper and lower end plates are connected and tightened by a plurality of tie rod bolts. An inclination correcting means capable of arbitrarily adjusting the dimension in the thickness direction, the inclination angle, and the inclination direction is inserted between the fuel cell constituent parts or between the fuel cell constituent parts and the end plate.

  Therefore, in the present invention, between the stacked fuel cell component parts or between the fuel cell component parts and the end plate, the thickness direction dimension, the inclination angle, and the inclination correction means capable of arbitrarily adjusting the inclination direction are interposed. In order to insert, the upper and lower end plates were brought close to each other while maintaining their parallel state with tie rod bolts, and then temporarily tightened, and then the thickness direction dimension, the inclination angle, and the inclination direction of the inclination correction means were adjusted to be stacked. An evenly distributed surface pressure can be applied to the fuel cell component.

  Therefore, the stress concentration in the cell plane that occurs during pressurization and tightening with only the tie rod bolt is not generated, and the separator can be prevented from being broken, chipped, deformed, or the like due to the stress concentration. For this reason, breakage due to pressurization of the separator is greatly reduced, and cost reduction, improvement of assembly quality, shortening of assembly time, etc. can be achieved by reducing defects.

  Hereinafter, a fuel cell stack and a fastening method thereof according to the present invention will be described based on each embodiment.

(First embodiment)
1 and 2 show a first embodiment of a fuel cell stack to which the present invention is applied and a tightening method thereof, FIG. 1 is a front view of the fuel cell stack, and FIG. 2 is a cross-sectional view showing components for constituting a fuel cell. FIG. 3 is a plan view of the upper end plate of the fuel cell stack, and FIG. 4 is a front view showing a stacked state of fuel cell component parts.

  In FIG. 1, the fuel cell stack 1 of the present embodiment has a fuel cell component 4 stacked on a lower end plate 3 placed on a stacking table 2 or the like, and an upper end plate 5 stacked on the upper end. The two end plates 3 and 5 are tightened in a direction approaching each other by the tie rod bolts 6 so that the fuel cell constituent parts 4 between the both end plates 3 and 5 are brought into contact with each other with a predetermined surface pressure. FIG. 1 does not show all the individual parts of these fuel cell constituent parts 4, but only shows an outline of the stacked state.

  The fuel cell component 4 is laminated with an insulator 4A, a terminal 4B, and an end separator 4C from a lower end plate 3, and a cell 4D (gas diffusion layer, polymer film, gas diffusion layer) and an intermediate layer thereon. The separator 4E is alternately stacked until a predetermined number of cells are stacked, and the end separator 4C, the terminal 4B, and the insulator 4A are stacked thereon.

  As shown in FIG. 2, the end-side separator 4C is formed so as to have a gas flow path for supplying the introduced gas to the gas diffusion layer on one side, and the intermediate separator 4F serves as the gas diffusion layer on both sides. It forms so that the gas flow path to supply may be provided. The cell 4D is formed by disposing a gas diffusion layer 4D2 on both sides of the polymer electrolyte membrane 4D1, and a seal 4D3 is integrally attached to the polymer membrane 4D1 around the gas diffusion layer 4D2 by pasting the entire circumference. Provided.

  Although not shown, the insulator is formed in an elastic body made of rubber or polymer, and can absorb thermal expansion and contraction accompanying the power generation operation of the fuel cell stack 1. The terminal 4B is a terminal for taking out the electric power generated by the power generation reaction of the fuel cell stack 1. Note that the manifolds of the respective gases and cooling water provided in the fuel cell component 4 are configured to open to the lower end plate 3 (not shown).

  As shown in FIG. 1, the upper end plate 5 is composed of a flat plate 7 and a tapered plate 8 divided into two in the stacking direction, and a plurality of tapered pieces 9 inserted between the plates 7 and 8. Correction means 11 are provided. As shown also in FIG. 3, the flat plate 7 (illustrated by a two-dot chain line) of the inclination correcting means 11 is a flat plate having a frame portion 7A on the outer periphery, and the tapered plate 8 (illustrated by a solid line). ) Is formed in a flat surface portion 8A having a flat central portion, and is formed in a slope portion 8B having a plate thickness that decreases from the flat surface portion 8A to the end portion as it approaches the end portion.

  The flat plate 7 is provided with a hole 7B through which the tie rod bolt 6 passes, and the bolt portion 6A at the tip of the tie rod bolt 6 is screwed to the lower end plate 3 by passing through the hole 7B. 6B is engaged through a washer or the like, and functions to press the tapered piece 9 and the tapered plate 8 against the fuel cell component 4 side.

  The tapered piece 9 has its tapered portion 9A in contact with the inclined surface portion 8B of the tapered plate 8, and the back surface of the tapered portion 9A is not separated from the flat plate 7 in the groove 7D provided in the flat portion 7C of the flat plate 7. It is movably engaged and disposed between both plates 7 and 8. The taper-shaped piece 9 is regulated in its retracted position by a fastening bolt 10 that is threadedly engaged with the frame portion 7A of the flat plate 7 and passes therethrough. Accordingly, when the tightening bolt 10 is loosened, the contact position on the inclined surface portion 8B of the taper plate 8 is moved to the end side to bring both plates 7 and 8 closer together, and when the tightening bolt 10 is tightened, the inclined plate portion 8B on the tapered plate 8 is moved. The contact position is brought close to the central plane portion 8A to act to separate the plates 7 and 8 from each other.

  As shown in FIG. 3, two tapered pieces 9 are arranged on the inclined surface portion 8 </ b> B of the taper plate 8. For this reason, the taper piece 9 on one inclined surface portion 8B of the taper piece 9 is simultaneously advanced or retracted to separate or approach the side of the plates 7 and 8 where the taper piece 9 that has been advanced and retracted is located. The taper piece 9 that is advanced or retracted can be moved away or approached by simultaneously advancing or retreating the taper piece 9 opposed across the plane portion 8A. Even if the tapered piece 9 and the sloped portion 8B are in linear contact, that is, in line contact, and the two plates 7 and 8 are not parallel to each other, the contact state between the tapered piece 9 and the sloped portion 8B is maintained. I try to be stable.

  The fuel cell stack 1 configured as described above can be assembled and tightened in the stacking direction from the state in which all the fuel cell component parts 4 are stacked in the following procedure.

  First, the taper plate 8 of the upper end plate 5 is laminated on the fuel cell stack 1 in which all the fuel cell component parts 4 are laminated. At the stage of stacking, variation in the shape accuracy in the thickness direction of the stacked fuel cell constituent parts 4, variation in thickness of seal adhesive, etc., and assembly variation are accumulated. For example, as shown in FIG. There is a case where the side is tilted or the upper end surface is inclined.

  Next, the flat plate 7 through which the tie rod bolt 6 is penetrated is positioned above the stacked fuel cell stack 1, and the tip screw portion 6 A of the tie rod bolt 6 is screwed into the screw hole of the lower end plate 3 to taper the flat plate 7. The shape piece 9 is brought into contact with the taper plate 8. If there is no tilting or tilting in the stacked state, the flat plate 7 and the taper plate 8 are in contact with each other on the flat surface portions 7C and 8A, but if the tilting or tilting occurs in the stacked state, the tilting or tilting occurs. Then, the inclined surface portion 8B of the taper plate 8 on the side protruding from the normal state comes into contact with the tapered portion 9A of the tapered piece 9 facing each other.

  From this state, the output from a plurality of axial force sensors formed by an axial force sensor on each tie rod bolt 6, for example, a strain gauge that detects the strain amount of the bolt shaft portion generated according to the axial force applied to the tie rod bolt 6. All the tie rod bolts 6 are tightened with a uniform stroke until the output value with the highest value reaches the preset temporary fixing set value.

  In this process, the fuel cell of the fuel cell stack 1 is in contact with the tapered portion 9A of the tapered piece 9 facing the inclined surface portion 8B of the tapered plate 8 on the side protruding from the normal state due to collapse or inclination in the stacked state. As shown in FIG. 4, the component 4 for a structure acts so that the fall may be returned by the contact of inclined surfaces. That is, a force that positively returns to the normal state by the contact between the slopes acts on the part that has fallen and protrudes from the normal state, and the slopes have a part that has fallen and retreats from the normal state. Since the contact pressure is small even if it does not contact or does not contact, the action of inducing the fall does not occur or the acting force is small.

  When the tie rod bolt 6 is screwed into the lower end plate 3 in this manner, the flat plate 7 is corrected by the tapered piece 9 through the taper plate 8 while correcting the falling of the fuel cell component 4. Gradually approaching the taper plate 8, all the tapered pieces 9 are brought into contact with the taper plate 8, and then a surface pressure of a temporarily fixed set value is applied to a part of the fuel cell component 4. This state can be determined when one of the axial force sensors of the tie rod bolt 6 reaches a preset temporary fixing set value.

  In this state, the upper surface of the flat plate 7 of the upper end plate 5 is in a parallel state with the lower end plate 3 by tightening with a uniform stroke of the tie rod bolt 6, and the taper plate 8 of the upper end plate 5 is Corrected to the normal state by tightening with a uniform stroke (may be completely corrected or in the middle of correction, there may be cases where only the upper surface is inclined and cannot be corrected without falling down) The upper end of the component 4 is in a tilted state or a tilted state placed following the tilted state or the tilted state.

  Next, the surface pressure distribution state of the fuel cell component 4 is determined from the output value of the axial force sensor of the tie rod bolt 6 to determine how the taper plate 8 is inclined, and the surface pressure distribution becomes uniform. As described above, the tightening bolt 10 of the tapered piece 9 closest to the tie rod bolt 6 having the lowest output value of the axial force sensor is gradually screwed in, and the tapered piece 9 is advanced to advance the tapered plate 8 through the slope portions 8B and 9A. A part is pressed against the fuel cell component 4 side to increase the axial force of the isotie rod bolt 6.

  When the increase in the axial force exceeds the axial force of another tie rod bolt 6 that outputs another lowest axial force, the screwing of the corresponding tightening bolt 10 is stopped, and the axial force becomes the lowest again. Similarly, the taper piece 9 closest to the tie rod bolt 6 is advanced by the fastening bolt 10 in the same manner, and similarly, a part of the taper plate 8 is pressed against the fuel cell component 4 side, and the axial force of the equal tie rod bolt 6 is increased. To raise. In this way, the tapered piece 9 is advanced so as to gradually increase the axial force of the tie rod bolt 6 from the lowest tie rod bolt 6, and the axial force of all the tie rod bolts 6 is set in advance as the fuel cell stack 1. When the axial force is reached, the position adjustment of the tapered piece 9 is completed.

  In this adjustment completion state, the flat plate 7 of the upper end plate 5 is in a parallel state with the lower end plate 3, and the taper plate 8 presses the stacked fuel cell component parts 4 in an equal surface pressure state. It is inclined with respect to the flat plate 7 by a tapered piece 9. As a result, the fall of the fuel cell component 4 in the stacked state can be absorbed, and a uniform axial force can be obtained.

  In the above-described embodiment, only the case where the stacked fuel cell component 4 is tilted or inclined in the plane of the front view has been described. The front view may occur in an oblique plane. Even in such a case, by adopting the procedure of the tightening method described above, the taper plate 8 is aligned with the stacked fuel cell component 4. Similarly, the fuel cell component 4 can be tightened with a uniform surface pressure.

  In the present embodiment, the following effects can be achieved.

  (A) A tie rod is interposed between the stacked fuel cell component 4 and the end plates 3 and 5 so as to insert a tilt correcting means 11 capable of arbitrarily adjusting the thickness direction dimension, the tilt angle, and the tilt direction. The upper and lower end plates 3, 5 were temporarily brought close to each other while maintaining their parallel state with the bolts 6, and then laminated by adjusting the thickness direction dimension, the inclination angle, and the inclination direction of the inclination correcting means 11. An evenly distributed surface pressure can be applied to the fuel cell component 4. Therefore, the stress concentration in the cell surface that occurs during pressurization and tightening with only the tie rod bolt 6 is not generated, and breakage such as cracking, chipping, and deformation of the separator due to the stress concentration can be prevented. For this reason, breakage due to pressurization of the separator is greatly reduced, and cost reduction, improvement of assembly quality, shortening of assembly time, etc. can be achieved by reducing defects.

  (A) As the inclination correction means 11, the relative distance and angle of each other can be arbitrarily changed, and at least one of the opposing surfaces to the other is provided with an inclined surface portion 8B whose thickness is reduced from the center side to the end portion. Since a plurality of pieces 9 as a plurality of interval changing members arranged between the two plates 7 and 8 and both the plates 7 and 8 and adjusting the interval between the plates 7 and 8 at the position are provided. The relative distance and angle between the plates 7 and 8 can be arbitrarily changed by changing the contact position with respect to the inclined surface portion 8B, and the surface pressure adjustment distributed evenly to the stacked fuel cell component parts 4 can be performed. Easy to do.

  (C) One of the plates 7 and 8 of the inclination correcting means 11 is constituted by an end plate 5, and a plate 8 having a slope portion 8B is laminated on the upper end of the laminated fuel cell component 4, The end plate 7 (5) on which the piece 9 is installed is brought into contact with the plate 8 at the upper end of the fuel cell component 4 from above, and thereafter, the upper and lower end plates 3 and 5 are brought close to each other by the tie rod bolt 6 and temporarily tightened. Then, in order to adjust the thickness direction dimension, the inclination angle, and the inclination direction of the inclination correcting means 11, the fuel cell constituent parts 4 are evenly distributed while correcting the inclination of the stacked fuel cell constituent parts 4. Can be applied.

(Second Embodiment)
FIG. 5 is a front view of a fuel cell stack showing a second embodiment of a fuel cell stack to which the present invention is applied and a tightening method thereof. In the present embodiment, an inclination correcting means is interposed between fuel cell constituent parts in the middle of stacking. The same devices as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified.

  In the fuel cell stack 1 of the present embodiment, as shown in FIG. 5, the two plates 7, 8 as the inclination correcting means 11 are fuel cell components 4 stacked between the upper and lower end plates 3, 5. They are stacked in the same manner as the fuel cell component 4. At least one of the two plates 7 and 8 is a slope whose central portion is formed as a flat plane portion 8A, and between the plane portion 8A and the end portion, the plate thickness decreases as the end portion is approached. The taper plate 8 is formed in the portion 8B. As shown in the drawing, both plates 7 and 8 may be formed in a tapered plate having a slope portion.

  A tapered piece 9 is interposed on the inclined surface of the plate 8, and a contact position on the inclined surface 8B of the tapered piece 9 can be adjusted by a tightening bolt 10 screwed to a frame portion 7A provided on one plate 7. It has become. When the plates 7 and 8 are laminated together with the fuel cell component 4, the tapered piece 9 is retracted to the end side, and the flat portions 7C and 8A are kept in contact with each other and maintained in a parallel state. It is assumed that it was done. As the fuel cell component 4 disposed adjacent to the plates 7 and 8, an end separator 4C is disposed, and the end separator 4C is disposed via the plates 7 and 8 and the tapered piece 9 formed of a conductive material. Configured to be conducted between.

  In the fuel cell stack 1 configured as described above, the tapered piece 9 is interposed as the inclination correcting means 11 when the fuel cell component 4 is stacked on the lower end plate 3 by, for example, half of the stack. The two plates 7 and 8 are stacked, the remaining half of the fuel cell component 4 is stacked, the upper end plate 5 is placed on the upper end, and the upper and lower end plates 3 and 5 are In the same manner as in the first embodiment, tightening is performed with a uniform stroke until one of the axial force sensors of the tie rod bolt 6 reaches a preset temporary fixing set value.

  In this state, the upper end plate 5 is in parallel with the lower end plate 3 by tightening the tie rod bolts 6 with an equal stroke, and the fuel cell components stacked between the end plates 3 and 5. 4 is tilted or inclined on the upper surface, a part of the upper end of the fuel cell component 4 contacts the upper end plate 5 in a temporarily fixed state, and the remaining upper surface and the upper end plate 5 are in contact with each other. There may be gaps.

  Next, the surface pressure distribution state of the fuel cell component 4 is determined based on the output value of the axial force sensor of the tie rod bolt 6, and the tie rod bolt 6 having the lowest output value of the axial force sensor so that the surface pressure distribution is uniform. The fastening bolt 10 of the taper piece 9 closest to is screwed in gradually, the taper piece 9 is advanced, and a part of both plates 7 and 8 are separated from each other via the slope portion 8B and stacked. The surface pressure applied to the component 4 is increased, and the axial force of the isotie rod bolt 6 is increased.

  When the increase in the axial force exceeds the axial force of another tie rod bolt 6 that outputs another lowest axial force, the screwing of the corresponding tightening bolt 10 is stopped, and the axial force becomes the lowest again. Similarly, the taper piece 9 closest to the tie rod bolt 6 is advanced by the tightening bolt 10 in the same manner, and similarly, a part of both plates 7 and 8 are separated to increase the surface pressure applied to the fuel cell component 4. The axial force of the corresponding tie rod bolt 6 is increased. In this way, the tapered piece 9 is advanced so as to gradually increase the axial force of the tie rod bolt 6 from the lowest tie rod bolt 6, and the axial force of all the tie rod bolts 6 is set in advance as the fuel cell stack 1. When the axial force is reached, the position adjustment of the tapered piece 9 is completed.

  In this adjustment completed state, the surface pressure is increased by increasing the distance between the plates 7 and 8 of the inclination correction means 11 in the portion where the surface pressure is low between the upper and lower end plates 3 and 5 in the parallel state by the tapered piece 9. The two plates 7 and 8 are tilted without being in a parallel state. As a result, the fall of the fuel cell component 4 in the stacked state can be absorbed, and a uniform axial force can be obtained.

  In addition, since the two plates 7 and 8 of the inclination correction means 11 are inclined from the parallel state according to the surface pressure in the intermediate stage of the stacking of the fuel cell component 4, they are stacked and fallen. Even the fuel cell component 4 is corrected so that the falling posture is close to the normal state.

  In the present embodiment, in addition to the effects (a) to (c) in the first embodiment, the following effects can be achieved.

  (D) Fuel that has been stacked and in a tilted state is interposed between the stacked fuel cell component parts 4 by means of the tilt correction means 11 that can arbitrarily adjust the thickness direction dimension, tilt angle, and tilt direction. Even in the battery component 4, the stacked fuel cell configuration can be obtained by adjusting the thickness direction dimension, the tilt angle, and the tilt direction of the tilt correction unit 11 while correcting the tilted posture to be close to the normal state. An evenly distributed surface pressure can be applied to the component 4 for use.

  In each of the above embodiments, the insulator 4A laminated as the fuel cell component 4 is given elasticity to absorb the thermal expansion and contraction during the fuel cell operation. An elastic body may be interposed between the piece 9 and the tightening bolt 10 to absorb thermal expansion and contraction during fuel cell operation.

The front view of the fuel cell stack which shows one Embodiment of this invention. Sectional drawing which similarly shows the components for fuel cell components. The top view of the upper end plate of a fuel cell stack. The front view which similarly shows the lamination | stacking state of the components for fuel cell components. The front view of the fuel cell stack which shows 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell stack 2 Stacking stand 3 Lower end plate 4 Fuel cell component 5 Upper end plate 6 Tie rod bolt 7, 8 plate 9 Tapered piece, piece 10 Tightening bolt 11 Tilt correction means

Claims (8)

In the fuel cell stack in which fuel cell components are stacked so as to constitute a plurality of cells between the upper and lower end plates, and the upper and lower end plates are connected and tightened by a plurality of tie rod bolts,
An inclination correction means capable of arbitrarily adjusting a thickness direction dimension, an inclination angle, and an inclination direction is interposed between the stacked fuel cell constituent parts or between the fuel cell constituent parts and the end plate. And fuel cell stack.   The inclination correction means includes two plates that can arbitrarily change the relative interval and angle of each other, a plurality of interval changing members that are arranged between both plates and adjust the interval between the plates at the position, The fuel cell stack according to claim 1, comprising: The inclination correction means includes, on at least one of the two plates, a sloped portion with a reduced thickness from the center side to the end on the surface facing the other plate,
The interval changing member is composed of a plurality of pieces interposed between the slope portion and the other plate,
3. The fuel cell stack according to claim 2, wherein a relative distance and an angle between the two plates are arbitrarily changed by changing a contact position of the piece with respect to the slope portion. 4.   4. The fuel cell stack according to claim 1, wherein one of the two plates is constituted by an end plate. 5. In a fuel cell stack tightening method in which fuel cell components are stacked so as to form a plurality of cells between upper and lower end plates, and upper and lower end plates are connected and tightened by a plurality of tie rod bolts.
Between the laminated fuel cell constituent parts or between the fuel cell constituent parts and the end plate, an inclination correcting means capable of arbitrarily adjusting a thickness direction dimension and an inclination angle and an inclination direction is inserted,
While maintaining the parallel state of the upper and lower end plates with tie rod bolts, temporarily tighten them close to each other,
Next, the thickness direction dimension, the inclination angle, and the inclination direction of the inclination correcting means are adjusted to apply a uniform surface pressure to the stacked fuel cell component parts. How to attach.   The inclination correcting means includes two plates that can arbitrarily change the relative interval and angle between each other, and a plurality of interval changing members that are arranged between both plates and adjust the interval between the plates at the position. 6. The structure according to claim 5, wherein the distance change member is operated to adjust the distance and angle between the two plates so that the axial force of all the tie rod bolts has a predetermined value set in advance. The method of tightening the fuel cell stack according to the description. The inclination correction means includes, on at least one of the two plates, a sloped portion with a reduced thickness from the center side to the end on the surface facing the other plate,
The interval changing member is composed of a plurality of pieces interposed between the slope portion and the other plate,
7. The method of tightening a fuel cell stack according to claim 6, wherein a relative position and an angle between both plates are arbitrarily changed by changing a contact position of the piece with respect to the slope portion. One of the two plates of the tilt correction means is constituted by an end plate,
Laminating a plate having a slope portion on the upper end of the laminated fuel cell components,
The end plate on which the plurality of pieces are installed is brought into contact with the upper plate of the fuel cell component from above,
After that, the upper and lower end plates are brought close to each other with tie rod bolts and temporarily tightened.
Next, the thickness direction dimension, the inclination angle, and the inclination direction of the inclination correcting means are adjusted to apply a uniform surface pressure to the stacked fuel cell component parts. The method of tightening the fuel cell stack according to the description.

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