JP5082430B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell including a tension plate that presses a fuel cell stack.

  A fuel cell stack in which fuel cells are stacked is usually tightened by applying a pressing force in the stacking direction.

  Patent Document 1 below discloses a technique in which a plate-like tension plate is passed between end plates disposed at both ends of a fuel cell stack, and a compressive force is applied between the end plates.

  Patent Document 2 listed below describes a technique in which fastening members are arranged at four corners of a fuel cell stack and tightened in the stacking direction. Four plates surrounding the side surface of the fuel cell stack are attached to the fastening member, and holes corresponding to exhaust ports of the fuel cell are provided on these plates.

JP 2002-367664 A JP 2004-327065 A

  In some cases, the side surface of the fuel cell stack is provided with a portion connected to the outside, such as an output terminal or a gas flow path. In this case, if the tension plate is wide, there is a risk of hindering the coupling.

  An object of the present invention is to realize a fuel cell that does not interfere with or reduces the interference between the fuel cell stack and the outside.

  On the other hand, when the tension plate is made narrow, a large external force acts on the connecting portion between the end side of the fuel cell stack and the tension plate.

  Another object of the present invention is to provide a fuel cell in which the distortion of the distribution of force acting on the connecting portion between the end side of the fuel cell stack and the tension plate is reduced.

  Still another object of the present invention is to reduce the weight of the fuel cell.

In one aspect of the fuel cell of the present invention, the fuel cell stack in which the fuel cells are stacked, and disposed on the side surface side in the stacking direction of the fuel cell stack, combined with both end sides in the stacking direction of the fuel cell stack, and a tension plate which gives a pressing force in the stacking direction to the fuel cell stack, the tension plate, the two coupling portions of the both end sides of the fuel cell stack, formed wider than the intermediate portion between the two coupling portions Has been.

  The tension plate is a plate-like member that is passed between both ends in the stacking direction of the fuel cell stack and applies a pressing force to the fuel cell stack. An extension force acts on the tension plate as a reaction of pressing. The joint portion of the tension plate refers to a joint portion with the end side of the fuel cell stack, and the intermediate portion of the tension plate refers to a general component between the joint portions (for example, more than half of the tension plate). In the part, it refers to a typical structural region).

When the fuel cell stack has a polygonal column shape, only one tension plate may be provided on the same side surface, or a plurality of tension plates may be provided. In addition, the number of surfaces on which the tension plate is provided may be only one surface or a plurality of surfaces, but it is considered that there are cases where it is better to provide symmetry so as to achieve a dynamic balance. When the side surface of the fuel cell is formed with a curved surface, the tension plate may be configured in a corresponding curved shape.

  The intermediate portion is typically formed in a straight line, but may be formed in a curved shape or may have an opening. Further, the coupling portion is typically made continuously (dense), but may be made in a discontinuous (sparse) structure in which holes are provided or formed in a fork shape. In any case, the width between the outermost edges of the coupling portion is made wider than the width between the outermost edges of the intermediate portion.

  According to this configuration, it is possible to reduce the weight of the tension plate as compared to the case where the tension plate is formed to have the same width as that of the coupling portion, and thus, the fuel cell can be reduced in weight. Thereby, advantages such as improvement in fuel efficiency of a fuel cell vehicle equipped with a fuel cell can be obtained. Further, according to this configuration, the tension plate and the end side of the fuel cell stack can be coupled in a relatively wide range, so that the force acting on the end side can be dispersed. The tension plate intermediate portion and the coupling portion may be made to have the same thickness. However, for example, the intermediate portion is relatively thick to reduce the difference in cross-sectional area between the intermediate portion and the coupling portion. It may be made with any thickness.

Further, the tension plate continuously increases in width from the intermediate portion side toward each coupling portion side. According to this configuration, concentration of stress acting on the tension plate can be avoided or reduced.

  In one aspect of the fuel cell of the present invention, the continuous width of the tension plate is increased in a shape that does not have a contour that is discontinuous and convex inward. According to this configuration, since there is no singular point where stress concentrates, it is possible to avoid or reduce stress concentration.

  In one aspect of the fuel cell of the present invention, an end plate that presses the fuel cell stack in the stacking direction is provided on the at least one end side, and the tension plate is coupled to the end plate, so that the fuel cell A pressing force in the stacking direction is applied to the stack, and the end plate on the at least one end side presses the fuel stack in a load region limited in the width direction of the fuel cell stack at the connecting portion, and the tension plate The intermediate portion is disposed on the inner side of at least one outer end of the load region, and the coupling portion of the tension plate extends to the outer side of the outer end of the load region. According to this configuration, it is possible to suppress the deformation of the end plate compared to the case where the coupling portion does not reach the outside of the load region.

  In one aspect of the fuel cell of the present invention, the end plate on the at least one end side presses the fuel stack through load adjusting screws provided at a plurality of locations in the width direction of the fuel cell stack at the coupling portion. The intermediate portion of the tension plate is disposed inside at least one of the outermost load adjustment screws, and the coupling portion of the tension plate extends to the outside of the outermost load region screw. An elastic body (for example, spring box) layer may be provided between the load adjusting screw and the fuel cell stack.

  In one aspect of the fuel cell of the present invention, the fuel cell includes a plurality of fuel cell stacks juxtaposed side by side, the fuel cell stacks are pressed by a common end plate, and the fuel cell stacks are juxtaposed. The same number of tension plates are juxtaposed on the side surface corresponding to the plurality of fuel cell stacks, and the intermediate portion of each tension plate is located on the inner side of the outer end of the load region for the corresponding fuel cell stack. The connecting portion of each tension plate extends to the outside of the outer end of the load region for the corresponding fuel cell stack.

  In one aspect of the fuel cell of the present invention, an output mechanism for diagnosing each fuel cell is provided on the side surface of the fuel cell stack, and the tension plate has a narrower intermediate portion than the coupling portion. It exists in the position where overlap with an output mechanism is avoided by being. As an example of the output mechanism for diagnosis, an output terminal provided for diagnosing each fuel cell, or a wiring connected to such an output terminal can be cited. According to this configuration, it is possible to facilitate attachment of the output mechanism or avoid interference between the output mechanism and the tension plate.

  In one aspect of the fuel cell of the present invention, an output mechanism for outputting power from the fuel cell stack is provided on the side surface of the fuel cell stack on the at least one end side, and the tension plate has the intermediate portion connected to the intermediate portion. It is arranged at a position where overlapping with the output mechanism is avoided by being narrower than the portion. The output mechanism for power output refers to a terminal for taking out the power generated by the fuel cell, or a wiring connected to the output terminal. The output terminals are typically provided at both ends of the fuel cell stack in the stacking direction. When there are a plurality of fuel cell stacks, the fuel cell stacks may be provided at both ends. However, if the fuel cell stacks are electrically connected, the number of output terminals may be smaller. The output terminal is a terminal for taking out a high voltage, and may be relatively large or formed in a protruding shape so that it can be connected with a certain contact area.

  This embodiment is illustrated below.

  FIG. 1 is a perspective view schematically showing a partial structure of a fuel cell 10 according to the present embodiment, and FIG. 2 is a top view of a front side portion of the fuel cell 10. However, in FIG. 2, illustration of tension plates 54 and 56 to be described later is omitted.

  The fuel cell 10 includes fuel cells 12, 14, 16,. . . Are electrically connected in series, and a stacked fuel cell stack 20 is provided. The fuel cells 12, 14, 16,. . . Is a polymer electrolyte fuel cell, and includes a pair of electrodes called an anode and a cathode, and an electrolyte membrane sandwiched between the electrodes. Each fuel cell 12, 14, 16,. . . Has a substantially square shape with a side of about a dozen centimeters and a thickness of about a few millimeters. The fuel cell 10 includes each fuel cell 12, 14, 16,. . . A mechanism for supplying a fuel gas such as hydrogen gas to the anode and supplying a gas such as air containing oxygen gas to the cathode is provided. Then, the fuel cell 10 generates electric power by leading the current flowing in the process of oxidizing the fuel gas to the external circuit. Further, fuel cell units 12, 14, 16,. . . Cell monitors 22 and 24 including an output terminal and a cable connected to the output terminal are provided.

  The fuel cell 10 is provided with a fuel cell stack 26 similar to the fuel cell stack 20 in parallel with the fuel cell stack 20. These fuel cell stacks 20 and 26 are electrically connected in series on the back side of the figure, and terminal plates 32 and 34 are provided at both ends (front side of the figure) for power output. . The terminal plates 32 and 34 are provided with output terminals 32a and 34a. The output terminals 32a and 34a are formed in a shape protruding on the same side surface (upper side in the drawing) of the fuel cell stacks 20 and 26, and connection to an external circuit by a bus bar, a cable, or the like is facilitated.

  Insulation plates 35 and 36 that insulate the terminal plates 32 and 34 are provided on the side of the fuel cell stacks 20 and 26 where the output terminals 32a and 34a are disposed (front side in the figure). A spring box 40 including an upper plate 37 and a lower plate 39 and a spring (spring) 38 sandwiched therebetween is provided on the front side of the insulating plates 35 and 36. The upper plate 37 and the lower plate 39 are each made of a single plate-like member and are sized to cover the cross sections of the fuel cell stacks 20 and 26. The spring box 40 functions as an elastic layer that compresses the fuel cell stacks 20 and 26 using the elastic force of the spring.

  An end plate 42 is provided on the front side of the lower plate 39, and an end plate 44 is provided on the back side of the fuel cell stacks 20 and 26. The end plates 42 and 44 are members for pressing the fuel cell stacks 20 and 26 from both ends thereof (pushing them to give a compressive force). The end plates 42 and 44 are made of a single plate-like member similarly to the upper plate 37 and the lower plate 39, and the size of the end plates 42 and 44 is sufficient to cover the cross sections of the fuel cell stacks 20 and 26. The end plates 42 and 44 are made of, for example, aluminum or stainless metal.

  Four load adjusting screws 46, 48, 50, 52 are provided between the end plate 42 and the lower plate 39. By changing the tightening degree of the load adjusting screws 46, 48, 50, 52, the pressing strength (compression strength) of the fuel cell stacks 20, 26 through the spring box 40, the right / left balance of pressing, and the like can be improved. be changed.

  Two tension plates 54 and 56 are disposed on one side surface (the upper surface in the figure) of the fuel cell stacks 20 and 26. Specifically, the tension plate 54 is disposed near the center of the upper surface of the fuel cell stack 20, and the tension plate 56 is disposed near the center of the upper surface of the fuel cell stack 26. The tension plates 54 and 56 are elongate plate-like members made of, for example, stainless steel, and one end thereof is coupled to the upper surface of the end plate 42 and the other end is coupled to the upper surface of the end plate 44. In the coupling portions 54b and 56b with the end plate 42, the tension plates 54 and 56 may be partially coupled by, for example, screwing or the like. However, here, a convex structure is provided over the entire width direction on the tension plates 54 and 56, and a concave structure corresponding to the end plates 42 and 44 is provided and fitted to each other so as to be coupled over the entire width direction. Has been done.

  The tension plates 54 and 56 apply a pressing force between the end plates 42 and 44, thereby pressing the fuel cell stacks 20 and 26. An extension force acts on the tension plates 54 and 56 as a reaction. In particular, when the fuel cell stacks 20 and 26 generate heat and expand due to a chemical reaction caused by power generation, the tension plates 54 and 56 apply a pressing force to the end plates 42 and 44 with a strong force while receiving a large extension force. A tension plate is also provided on the side surface on the back side of the fuel cell stacks 20 and 26, and presses the end plates in cooperation with the tension plates 54 and 56.

  FIG. 3 is a top view of the front side of the fuel cell 10. In FIG. 3, tension plates 54 and 56 omitted in FIG. 2 are depicted.

  The tension plates 54 and 56 are formed in a relatively narrow and linear shape at a general location (referred to as intermediate portions 54a and 56a) between the end plates 42 and 44. The intermediate portion 54a is disposed so as not to overlap the output terminal 32a of the terminal plate 32. Similarly, the intermediate portion 56a is disposed so as not to overlap the output terminal 34a of the terminal plate 32. Further, the intermediate portion 54a is disposed between the cell monitors 22 and 24, and the intermediate portion 56a is disposed between the cell monitors 28 and 30, thereby avoiding duplication with the cell monitors 22, 24, 28, and 30. If attention is paid to the relationship between the load adjustment screws 46, 48, 50, 52, the intermediate portion 54 a is disposed so as to be positioned between the load adjustment screws 46, 48, and the intermediate portion 56 a As can be seen from FIG.

  The tension plates 54 and 56 are spread from the vicinity of the spring box 40 toward the coupling portions 54b and 56b with the end plate 42. That is, the coupling portions 54b and 56b are formed wider than the intermediate portions 54a and 56a, and are coupled to the end plate 42 over the wide width. Specifically, the coupling portion 54b is made wide enough to contact the output terminal 32a and the cell monitors 22 and 24 if the intermediate portion 54a is formed with this width. Similarly, the coupling portion 56b is made wide enough to contact the output terminal 34a and the cell monitors 28, 30 if the intermediate portion 56a is formed with this width. Further, the coupling portion 54 b reaches both outer sides of the load adjustment screws 46 and 48, and the coupling portion 56 b reaches both outer sides of the load adjustment screws 50 and 52.

  FIG. 4 is a diagram schematically showing the force acting on the end plate 42 when the tension plates 54 and 56 having the wide coupling portions 54b and 56b are employed. First, forces 70, 72, 74, and 76 are applied to the end plate 42 through the load adjusting screws 46, 48, 50, and 52 in a direction that extends between the end plates 42 and 44. On the other hand, the tension plate 54 has a force 80, 82,... In the direction in which the end plate 42 is compressed between the end plates 42, 44 over a wide area including the forces 70, 72. . . (If the bond is continuous, the forces 80, 82, ... are distributed continuously). The forces 80, 82,. . . It does not always work uniformly, but generally acts unevenly reflecting the distortion of the end plate 42. Similarly, the tension plate 56 is applied to the end plate 42 over a wide area including forces 74, 76, with forces 90, 92,. . . Is acting. As a result of these forces acting, in the end plate 42, the moment for bending the end plate 42 is relatively weak. That is, the end plate 42 does not undergo a great deformation.

  FIG. 5 is a schematic diagram for comparison with FIG. Here, in place of the tension plates 54 and 56 shown in FIGS. 1 to 4, tension plates 100 and 102 in which the widths of the intermediate portions 54a and 56a are also maintained by the coupling portions 54b and 56b are used. Then, the tension plate 100 is applied only between the load adjusting screws 46, 48 with the forces 110, 112,. . . , And the tension plate 102 is applied with the forces 120, 122,. . . Is acting. For this reason, the forces 70, 72, 74, 76 are applied to the end plate 42 in the direction of extending between the end plates 42, 44, while the forces 110, 112,. . . Acts and forces 120, 122,. . . Is working. Thereby, the end plate 42 receives a relatively large moment and causes a relatively large deformation. That is, it is relatively deformed so that it is drawn in the compression direction at the position of the tension plates 100 and 102 and is pushed back in the extension direction around the tension plates 100 and 102.

  Next, another example of the tension plate shape will be described with reference to FIG. FIG. 6 is a top view showing one end side of the tension plate. Here, the shape for avoiding the overlap with the output terminal 32a arranged on one side of the tension plate is examined.

The tension plate 130 of the reference example shown in FIG. 6 is formed in a shape substantially similar to the tension plates 54 and 56 described with reference to FIGS. That is, an intermediate portion 132 having a narrow linear shape and a wide coupling portion 134 are provided. However, the tension plate 130 does not simply expand in a divergent shape from the intermediate portion 132 toward the coupling portion 134, and the intermediate portion 132 and the coupling portion 134 are disposed between the intermediate portion 132 and the coupling portion 134 on the side where the output terminal 32 a exists. The constricted portion 136 is narrower than the width 132 by a reduced width w. The width is widened from the constricted portion 136 to the coupling portion 134 with a curved shape having a relatively large radius of curvature r1 (not necessarily having a constant radius of curvature).

  On the other hand, in a tension plate that does not have a constricted portion (for example, tension plates 54 and 56 shown in FIGS. 1 to 4), as shown by a two-dot chain line 138, a comparison is made from the vicinity of the output terminal 32a to the end side. The width is abruptly widened with a curved shape having a small radius of curvature r2. The width at the position 140 in the vicinity of the output terminal 32a is the same in both the shape shown by the two-dot chain line 138 and the tension plate 130. However, since the two-dot chain line 138 needs to be connected in a straight line shape with this position as a boundary, the bending of the divergent shape must be abrupt. On the other hand, in the tension plate 130, the divergent shape and the linear shape are loosely connected using the constricted portion 136 closer to the intermediate portion 132 than the position 140, so that the bend of the divergent shape becomes smooth.

  In general, the degree of stress concentration increases in a portion where the curve is sharp. Therefore, it is effective to provide a constricted portion 136 having an appropriate reduced width w and to form a divergent shape with a corresponding relatively large curvature radius r. However, if the reduction width w (and the curvature radius r) is increased, good results are not always obtained. This point will be described with reference to FIG.

  FIG. 7 shows the relationship between the reduction width w and the curvature radius r obtained by numerical analysis, and the maximum value of the stress acting on the tension plate. In this analysis, for the tension plate made of stainless steel (SUS304) with a thickness of 1.5 mm, the shape as shown in FIG. 6 and the conditions such as the load position and size by the load adjusting screw are set appropriately. Yes. Therefore, it should be noted that the obtained numerical value changes according to the setting conditions. However, it is considered that the qualitative characteristics shown here are not changed by slightly changing the setting conditions.

  In the range of the reduction width w from 0 mm to 10 mm (the corresponding curvature radius r is in the range of 19 mm to 47.5 mm), the stress value becomes the largest (483 MPa) when the reduction width w is 0 mm. When the reduction width w is 4 mm, the stress value is minimum (406.9 MPa), and in the range where the reduction width w is about 6 to 10 mm, the stress value is about 430 MPa.

  As can be seen, in general, it can be seen that the stress can be reduced by providing the constricted portion compared to the case of not providing the constricted portion. In addition, the stress becomes smaller when the degree of constriction (reduction width) is not made too large. This is presumed to be because, when the constriction increases, the positive effect of stress dispersion due to the increase in the radius of curvature is offset by the negative effect of stress concentration due to the decrease in the tension plate width.

  Finally, with reference to FIG. 8, a supplementary explanation will be given regarding the contour shape of the tension plate. The tension plate 150 shown in FIG. 8 includes an intermediate portion 152 having a constant width, an enlarged portion 154 whose width is increased at a constant ratio, and a wide coupling portion 156 having a constant width. The contour 158 of the intermediate portion 152, the contour 160 of the enlarged portion 154, and the contour 162 of the coupling portion 156 are all linearly formed. For this reason, at the boundary 164 between the intermediate portion 152 and the enlarged portion 154, the tangent lines 166 and 168 of the respective contours are discontinuous and have contour shapes that are convex inward. In other words, there is no material on the upper side of the letter “V”, and there is a material on the lower side. Further, at the boundary 170 between the enlarged portion 154 and the coupling portion 156, the tangent lines 172 and 174 of the respective contours are discontinuous and have contour shapes that are convex outward. In other words, the shape is such that there is no substance on the upper side of the letter “he” and there is a substance on the lower side.

  In general, even if the tangent of the contour is discontinuous like the boundary 170, the stress tends to be dispersed in a point that is convex outward. However, at the point where the tangent of the contour is discontinuous and convex inward as in the boundary 164, there is a high possibility that the stress is a singular point where stress is concentrated. Therefore, in order to increase the strength of the tension plate, it may be desirable to increase the width so as not to have a shape like the boundary 164. In other words, the continuous expansion of the tension plate is performed with a smooth contour shape in which the tangent is continuous, or a contour shape that is convex outward at the discontinuous point even if the tangent is discontinuous. It is thought that there may be a case where it is good to be done. In addition, although such a contour shape may include a straight line portion, smoothness may be enhanced as a curved line.

It is a perspective view of the fuel cell concerning this embodiment. It is a top view of a fuel cell in which a tension plate is omitted. It is a top view of a fuel cell including a tension plate. It is a schematic diagram which shows the force which acts on an end plate. It is a schematic diagram which shows the force which acts on the end plate of a reference aspect. It is a top view which shows the shape of the reference example of a tension plate. It is a figure which shows a numerical analysis result. It is a top view which shows the reference shape of a tension plate.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Fuel cell, 12, 14, 16 Fuel cell, 20, 26 Fuel cell stack, 22, 24, 28, 30 Cell monitor, 32, 34 Terminal plate, 32a, 34a Output terminal, 35, 36 Insulation plate, 37 Upper plate , 38 Spring, 39 Lower plate, 40 Spring box, 42, 44 End plate, 46, 48, 50, 52 Load adjusting screw, 54, 56, 100, 102, 130, 150 Tension plate, 54a, 56a Intermediate part, 54b 56b coupling part.

Claims (7)

A fuel cell stack in which fuel cells are stacked; and
A tension plate that is disposed on a side surface in the stacking direction of the fuel cell stack, and is coupled to both ends of the stacking direction of the fuel cell stack to apply a pressing force in the stacking direction to the fuel cell stack;
With
Tension plate in two coupling portions of the both end sides of the fuel cell stack, which is wider than the intermediate portion between the two coupling portions, and toward the respective coupling portion from said middle portion A fuel cell characterized by continuously expanding the width . The fuel cell according to claim 1 , wherein
The fuel cell is characterized in that the continuous width expansion of the tension plate is performed in a shape having no contour such that the tangent is discontinuous and convex inward. The fuel cell according to claim 1 or 2 ,
At least one end side is provided with an end plate that presses the fuel cell stack in the stacking direction,
The tension plate is coupled to the end plate to give a pressing force in the stacking direction to the fuel cell stack,
The end plate on the at least one end side presses the fuel stack in a load region limited in the width direction of the fuel cell stack,
The intermediate portion of the tension plate is disposed inside at least one outer end of the load region,
Each of the coupling portions of the tension plate extends to the outside of the outer end of the load region. The fuel cell according to claim 3 , wherein
The end plate on the at least one end side presses the fuel stack through load adjusting screws provided at a plurality of positions in the width direction of the fuel cell stack,
The intermediate portion of the tension plate is disposed inside at least one outermost load adjustment screw,
Each of the connecting portions of the tension plate extends to the outside of the outermost load region screw. The fuel cell according to claim 3 , wherein
The fuel cell includes a plurality of fuel cell stacks juxtaposed adjacent to each other,
Both fuel cell stacks are pressed by a common end plate,
On the side surface where the fuel cell stacks are juxtaposed, the same number of tension plates are juxtaposed corresponding to the plurality of fuel cell stacks,
The intermediate portion of each tension plate is disposed inside the outer end of the load region for the corresponding fuel cell stack,
Each of the connecting portions of each tension plate extends to the outside of the outer end of the load region for the corresponding fuel cell stack. The fuel cell according to claim 1, wherein
On the side surface of the fuel cell stack, an output mechanism for diagnosing each fuel cell is provided,
The tension plate is disposed at a position where the intermediate portion is narrower than each of the coupling portions so that an overlap with the output mechanism is avoided. The fuel cell according to claim 1, wherein
On the side surface of the fuel cell stack, an output mechanism for outputting power from the fuel cell stack is provided on at least one end side of the fuel cell stack ,
The tension plate is disposed at a position where the intermediate portion is narrower than the coupling portion on the output mechanism side so that overlapping with the output mechanism is avoided.

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