JP2003045453A - Separator for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compatibly secure current collecting performance, gas diffusing performance and draining performance, in a separator for a fuel cell. SOLUTION: Linear parts 511 defined by rectangular projecting parts 42, 43 longitudinally lining up in tandem are provided in a passage groove 51, and the projecting parts 42, 43 are disposed so that the tandem of the projecting parts 42, 43 on one side rim of each linear part 511 and the projecting parts 42, 43 on the other are offset in the tandem direction of the projecting parts 42, 43. Thereby, an action caused by the discontinuous parts 42a of the projecting parts 42, 43 while disturbing gas flow and hampering formation of laminar flow is controlled so as not to repeatedly work on the same position of the linear part 511 of the passage groove, and the number of the discontinuous parts 42a of the projecting parts can be reduced without harming an action to enhance gas diffusing performance by expediting the flow velocity on an electrode surface. Thereby, current collecting performance is secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell separator forming a partition wall of a battery cell constituting a fuel cell.

[0002]

2. Description of the Related Art In a fuel cell, electrodes supporting a catalyst are stacked on the upper and lower surfaces of an electrolyte membrane to form a battery cell, and the battery cell and the separator are alternately laminated so that the electrode and the separator face each other. It has a structure. The separator is provided with a protrusion protruding toward the electrode side, and serves as a collector electrode for conducting the electrodes of the battery cells adjacent to each other with the separator sandwiched between them, and fuel gas and oxidation in the gap between the separator and the electrode. It plays the function of flowing gas and supplying it to the electrodes. A fuel gas is caused to flow along one of the surfaces facing the separator and an oxidizing gas is caused to flow along the other surface thereof, and these gases are respectively supplied to the corresponding electrodes. Thereby, the battery cells to be stacked are connected in series, and a high voltage can be taken out according to the number of stacked layers.

Therefore, it is desired that the separator has a property that the fuel gas and the oxidizing gas are easily diffused to the surface of the electrode (diffusion property) and that the conduction with the electrode is sufficient (collection property).

As a shape of the separator, there is a shape in which a plurality of elongated convex portions are provided in a ridge shape on the surface so that a plurality of linear flow channel grooves are formed in parallel. Further, as shown in FIG. 12, in a shape in which the flow paths are folded and meandering in the vicinity of the opposite sides of the separator 9, a plurality of linear flow path grooves are formed in parallel in a part thereof. There is also.
In the illustrated example, the plurality of elongated protrusions 911 and 913 form linear flow channel grooves 921 and 923. In the folded portion of the flow passage, a large number of small convex portions 912 are arranged in the vertical and horizontal directions, so that the flow passage groove 922 has a lattice shape (Japanese Patent Laid-Open No. 10-106594). In such a thing having a linear flow path groove, since the occupying area of the convex portion is large, the current collecting property is good, and the water included in the gas for humidification for enhancing the characteristics of the battery cells, Since the water generated by the chemical reaction between the fuel gas and the oxidizing gas easily flows, it is said that the drainage is good. Furthermore, the positive flow is formed from the upstream side to the downstream side of the flow path groove to increase the flow velocity, thereby improving the gas diffusibility.

[0005]

By the way, in the case where the flow path groove has a linear portion as in the above-mentioned Japanese Patent Application Laid-Open No. 10-106594, the inventor has earnestly conducted experimental research, and as a result, the following problems have occurred. It became clear. That is, the cross-sectional area of the flow path is very narrow because it is necessary to secure the current collection property, and the gas flow is likely to be a laminar flow in the linear portion. Therefore, a boundary layer is formed near the surface of the electrode, and the flow is not so fast near the surface of the electrode for the average flow velocity known from the flow rate.
In fact, it became clear that gas diffusivity was not sufficiently improved. Further, for this reason, water is likely to adhere to the wall surface, and there is a concern that the drainage performance may be deteriorated.

This problem is caused by dividing the convex portions arranged along the linear flow channel and arranging a large number of small convex portions 914 in a column as shown in FIG. If so, it will be improved. In this structure, the flow path groove linear portion 92
The gas flowing through 41 is formed by a plurality of protrusions 914 arranged in a column.
As a side wall, the side wall of the channel groove 924 is interrupted at a position where one convex portion 914 moves to the next convex portion 914. For this reason, the gas flow is disturbed to hinder the development of the boundary layer, and the flow velocity near the surface of the electrode can be increased.

However, when the convex portion is divided into a large number of small convex portions, the area occupied by the convex portion is reduced and the current collecting performance is impaired.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a fuel cell separator which has good gas diffusion and drainage properties without impairing current collection.

[0009]

According to a first aspect of the present invention, there is provided a separator forming a partition wall of a battery cell in which fuel cells are stacked, and a convex portion which is in contact with an electrode of the battery cell and is conductive is provided on the surface of the separator. At the same time, the flow path groove in which the fuel gas or the oxidizing gas supplied to the electrode flows through the gap with the electrode is formed by the non-projecting portion, and the flow path groove includes a plurality of linear portions parallel to each other. In the fuel cell separator, as the convex portion arranged along the linear portion of the flow channel,
A rectangular convex portion having a long side that defines the side edge of the linear portion, and provided with a plurality of convex portions arranged in a row along the linear portion, and the flow channel groove linear portion The convex portion is formed asymmetrically on one side edge side and the other side edge side.

As described above, the action of disturbing the flow occurs at the position where the convex portion is discontinuous and the side wall of the flow channel is interrupted. This action occurs in the two linear portions of the flow channel groove that are adjacent to each other with the convex portion interposed therebetween. Therefore, in the separator in which the flow channel has a lattice shape as shown in FIG. 13, for each of the flow channel linear portions, the above-described action caused by the convex discontinuity portion on one side edge side and the other The above-mentioned action produced by the convex discontinuous portion on the side edge side overlaps.

On the other hand, in the present invention, the convex portions are formed asymmetrically on one side edge side and the other side edge side of the flow path groove linear portion, so that the action of disturbing the flow is The convex edge discontinuous portion on the side edge side and the convex edge discontinuous portion on the other side edge side do not overlap with each other, and the efficiency is good. Accordingly, it is possible to reduce the discontinuous portion of the convex portion where the convex portion is not formed, and to secure the area occupied by the convex portion without reducing the effect of disturbing the gas flow. As a result, the current collecting property and the gas diffusibility and drainage property are compatible with each other.

According to a second aspect of the present invention, in the structure of the first aspect of the invention, the convex portions arranged along the straight line portion of the flow channel have a single shape, and the plural convex portions arranged in the column are formed. Are arranged so that the convex portion formed on one side edge side of the flow path groove linear portion and the convex portion formed on the other side edge side are offset in the column direction.

The positions of the protrusion discontinuities are offset in the column direction of the protrusions on one side edge side and the other side edge side of the flow path groove linear portion. Therefore, the effect of disturbing the gas flow does not overlap between the convex discontinuity portion on one side edge side and the convex discontinuity portion on the other side edge side. Moreover, since the shape of the convex portion may be a simple rectangle, the separator can be easily processed.

According to a third aspect of the present invention, in the configuration of the first aspect of the invention, the plurality of columnarly arranged convex portions have a long side whose one side is closer to one side edge of the linear portion of the flow channel. The convex portion formed on the side and the convex portion formed on the other side edge side have different shapes.

Since the size of the long side is different between the one side edge side and the other side edge side of the flow path groove linear portion, the pitch of the protrusions to be arranged in the column direction in the column direction is also different from the one side edge side and the other side edge side. It differs from the side edge. Therefore, the convex discontinuity also shifts between one side edge side and the other side edge side of the flow path groove linear portion. Accordingly, the action of disturbing the gas flow does not overlap between the convex discontinuity on one side edge and the convex discontinuity on the other side edge. Moreover, since the shape of the convex portion may be a simple rectangle, the separator can be easily processed.

According to a fourth aspect of the present invention, there is provided a separator forming a partition wall of battery cells stacked in a fuel cell, the surface of which is provided with a convex portion that is in contact with an electrode of the battery cell to conduct electricity, and a convex portion is not formed. The portion forms a flow channel groove in which the fuel gas or the oxidizing gas supplied to the electrode flows in the gap between the electrode and the flow channel groove, and in the fuel cell separator including a plurality of linear portions parallel to each other, The side surface or the bottom surface of the linear portion of the flow path groove has a stepped shape in which unevenness is repeated in the lengthwise direction of the linear portion.

The gas flowing in the straight portion of the flow channel is discontinuous on the side surface or the bottom surface of the flow channel at the step, and the flow is disturbed to hinder the development of the boundary layer, and the gas near the surface of the electrode is disturbed. The flow velocity can be increased. Gas diffusivity and drainage are improved according to the number of repetitions of irregularities in the straight portion of the flow channel groove. This does not depend on whether or not the side wall of the linear portion of the flow channel is interrupted, so that the required current collecting property can be secured.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) FIG. 1 shows a fuel cell separator according to a first embodiment of the present invention (hereinafter, appropriately referred to as a separator), and FIG. 2 shows a fuel cell to which the separator is applied. The cross-sectional structure of the essential part of is shown. The separator 11 is made of a known material such as dense carbon, which is gas impermeable and has desirable characteristics as a separator, and has a rectangular plate shape.
Are alternately laminated to form a partition wall of the battery cell 12. The battery cell 12 may have a general structure in which electrodes 121 and 122 made of porous layers capable of diffusing gas are superposed on both surfaces of the electrolyte membrane 120.

The back surface 1101 of the separator 11
Each of the electrodes 1102 has electrodes 121 of the battery cell 12,
A large number of protrusions 41, 42, 43 protruding toward 122 are formed, and the electrodes 121, 12 of the battery cell 12 are formed on the upper surface of the step.
The electrodes 121 and 122 and the separator 11 are electrically connected to each other. Further, the spaces formed in the non-formation portions such as the convex portions 42 are flow paths 31, 32 in which a fuel gas such as hydrogen-rich gas containing hydrogen or an oxidizing gas such as air containing oxygen flows through the gaps with the electrodes 121, 122. These gases flowing through the flow channels 31 and 32 diffuse into the electrodes 121 and 122 from the surfaces of the electrodes 121 and 122 that are not in contact with the separator 11.

In the vicinity of the left and right opposing sides of the separator 11 in FIG.
The fuel gas introduction hole 21 for introducing the first flow path groove 51, 52 and the fuel gas discharge hole 26 for discharging the fuel gas from the flow path groove 51, 52 are formed at diagonal positions. . In addition, the oxidizing gas is applied to the other surface 11 of the separator 11.
Oxidation gas introduction hole 2 for introduction into the channel groove (not shown) of 02.
4 and an oxidizing gas discharge hole 23 for discharging the oxidizing gas from the channel groove are formed at different diagonal positions. Further, cooling water passage holes 22 and 25 for forming cooling water passages for circulating the cooling water are formed.

The convex portions 41 to 43 on the one surface 1101 of the separator 11 and the flow channel grooves 51 and 52 whose shapes are defined by the convex portions 41 to 43 will be described. A frame-shaped convex portion 41 is formed on the separator 11 so as to frame it.
The frame-shaped convex portion 41 is formed outside the formation portion of the fuel gas introduction hole 21 and the fuel gas discharge hole 26, and the fuel gas can flow in the range surrounded by the frame-shaped convex portion 41.

Two flow path forming ribs 411 and 412 are extended from the frame-shaped convex portion 41. The first flow path forming rib 411 extends laterally from the vicinity of the fuel gas introducing hole 21 at a position of about 1/3 from the top in the drawing, and the second flow path forming rib 41 is formed.
2 is the fuel gas discharge hole 26 at a position approximately 1/3 from the bottom in the figure.
It extends laterally from the vicinity of. Thereby, as a whole, the flow path 31 of the fuel gas that meanders in an S shape from the fuel gas introduction hole 21 and reaches the fuel gas discharge hole 26 is formed.

In the meandering flow path 31, in the folded-back portions 312 and 314 which are folded back between the upstream portion 311 and the midstream portion 313 and between the midstream portion 313 and the downstream portion 315, the square convex portions 44 are vertically and horizontally equally spaced. And the flow path grooves 52 are in the shape of a lattice. As a result, the folded portions 312, 3
In 14, the gas and water do not stay and the flow direction changes smoothly.

The upstream portion 311, the middle flow portion 313 of the flow path 31,
In the downstream portion 315, the flow channel groove 51 has the flow channel forming rib 41.
Convex portions 42, 4 arranged in parallel in a direction parallel to 1, 412
3 is formed. The columns of the convex portions 42 and 43 are
Plural elements are arranged in the direction orthogonal to the flow path forming ribs 411 and 412 at the same intervals as the arrangement intervals of the convex portions 44 of the flow path turn-back portions 312 and 314. As a result, a plurality of linear portions 511 that are parallel to each other are formed in the flow path groove 51, with the convex portions 42 and 43 arranged in the respective columns as side walls. The adjacent linear portions 511 communicate with each other at the position where the side wall is interrupted, that is, at the discontinuous portion 42a of the convex portions 42 and 43. In the description, the flow path groove 51 is strictly different in the upstream portion 311, the midstream portion 313, and the downstream portion 315, but is simply the difference in length and is not an essential part of the present invention. Described in.

Convex portion 4 that defines the linear portion 511 of the flow channel.
Reference numerals 2 and 43 are rectangles of the same shape except for the convex portion 43 provided at a position adjacent to the fuel gas introduction hole 21, a position adjacent to the folded portions 312 and 314, and a position adjacent to the fuel gas discharge hole 26. The longitudinal direction is the column arrangement direction. The length of the short side of the convex portion 42 is equal to that of the folded portions 312, 31.
4 is the same as the length of the side of the convex portion 44.

Here, a plurality of convex portions 42 arranged in a row are arranged.
Are arranged so as to be offset in the column direction on one side edge side and the other side edge side of the flow path groove linear portion 511, and the flow path groove 51 has a crease shape. The offset amount is set to half the arrangement pitch of the convex portions 42 in the column direction. The convex portion 43 is provided in addition to the convex portion 42 so that the fuel gas introduction hole 21 can be provided even if such an offset is present.
This is because the positions of the short sides of the protrusions 42 and 43 in each column are aligned at the position adjacent to the, the position adjacent to the folded portions 312 and 314, and the position adjacent to the fuel gas discharge hole 26.

On the other surface 1102 of the separator 11 is also formed an S-shaped meandering channel 32 extending from the oxidizing gas introducing hole 24 to the oxidizing gas discharging hole 23, and the convex portions have the same shape and arrangement. There is.

The operation of the separator 11 will be described. The fuel gas from the fuel gas introduction hole 21 passes through the S-shaped meandering flow path 31 and escapes to the fuel gas discharge hole 26, but the fuel flowing into the flow path groove 51 from the fuel gas introduction hole 21 and the folded portions 312 and 314, respectively. The gas is divided into a plurality of flow path groove linear portions 511 and flows. The flow path groove linear portion 511 is narrow, and this acts in a direction that promotes the formation of a boundary layer near the wall surface of the flow path groove as it goes deeper from the upstream end. Here, the adjacent flow path groove linear portions 511 communicate with each other by the projections 42 and 43 forming the common flow path groove side wall being interrupted at a predetermined interval. Therefore, at the position where the side wall of the flow path groove is interrupted, that is, at the convex discontinuous portion 42a, the action of disturbing the gas flow occurs. Therefore, the development of the boundary layer is hindered, and the fuel gas diffusivity and drainage are improved.

Moreover, in the present separator 11, as described above, the plurality of convex portions 42, 43 arranged in a column on one side edge side and the other side edge side of the flow path groove linear portion 511 are offset in the column direction. Since it is located at, it has the following effects.

FIG. 3 shows a comparative example for explaining the effect of the present invention. In the comparative example, in the configuration of the separator 11, instead of the channel groove 51, the channel groove 71 is formed by the convex portions 61 and 62. The convex portions 61 have the same shape and the same number as the convex portions 42, and the convex portions 62 have the same shape and the same number as the convex portions 43. Therefore, the total area of the convex portions is the same as that of the separator of this embodiment, and the current collecting property is equivalent to that of the separator of this embodiment.

The difference from the separator 11 of the present embodiment of the comparative example is the arrangement of the convex portions 61 and 62. The separator of the comparative example also has the convex portion 6 parallel to the flow path forming ribs 411 and 412.
1, 62 are arranged in tandem, and the same number of flow channel linear portions 711 as the flow channel linear portions 511 of the separator 11 are provided.
Is formed. However, the plurality of convex portions 61 and 62 that are arranged in series on one side edge side and the other side edge side of the flow path groove linear portion 711 are not offset, and as is known from the figure, the flow path groove 71 is formed. It is not a hump-like shape, but a lattice shape like the folded-back portion.

4A and 4B are enlarged views of the surface of the separator, FIG. 4A shows the separator 11 of the present embodiment, and FIG. 4B shows the separator of the comparative example. belongs to. As described above, the flow channel groove linear portion 511,
711 the side wall of 711 is interrupted and the convex discontinuous portions 42a, 61a
Thus, an action of disturbing the gas flow (hereinafter, appropriately referred to as a boundary layer prevention action) occurs. In the case of the comparative example (FIG. 4 (B)), paying attention to the flow path groove linear portion 711 indicated by the arrow in the figure, when the gas flow is followed, the boundary layer prevention action occurs at the position PB1, for example. Next occurs at position PB2. On the other hand, in the case of the present embodiment (FIG. 4 (A)), paying attention to the flow path groove linear portion 511 indicated by the arrow in the figure, when the gas flow is traced, the boundary layer prevention action is performed at, for example, the position PA1. Then, it occurs at position PA2.

In FIGS. 4A and 4B, the position P is shown.
The convex discontinuities 42a and 61a which produce the boundary layer preventing action acting on A1, PA2, PB1 and PB2 are indicated by "." The boundary layer preventing action generated by the convex discontinuous portions 42a and 61a extends to both of the adjacent flow path groove linear portions 511 and 711, but in the comparative example in which the flow path grooves 71 are in the grid shape, While the convex portion discontinuous portion 61a on one side edge side of the groove linear portion 711 and the convex portion discontinuous portion 61a on the other side edge side overlap, in the present embodiment, they do not overlap. . Therefore, in the comparative example, the distance from the position PB1 to the position PB2 is the arrangement pitch in the column direction of the protrusions 61, whereas in the present embodiment, the distance from the position PA1 to the position PA2 is the column of the protrusions 42. It becomes 1/2 of the arrangement pitch in the direction.
As described above, according to the present embodiment, each flow path groove linear portion 5 is
In 11, the site where the boundary layer prevention action occurs is doubled.

FIG. 5 shows the distribution of the gas flow velocity in the flow channel in the width direction of the flow channel. This embodiment (A in the figure).
And a comparative example (B in the figure) are also shown. The measurement position is located at a cross-sectional position along the line AA and a cross-sectional position along the line BB, which is intermediate between the position PA1 (PB1) where the boundary layer preventing action occurs and the position PA2 (PB2) which occurs next. As shown in FIG. 6, the flow velocity is a direction orthogonal to the groove width direction (Y) and the groove depth direction (Z), that is, the vertical direction of the convex portions. It can be seen that in the present embodiment, the difference between the flow velocity in the central portion in the groove width direction and the flow velocity in the vicinity of the side edge of the flow channel is smaller and the boundary layer prevention action is greater than in the comparative example. Therefore, it is recognized that the present embodiment is superior to the comparative example in terms of gas diffusibility and drainage at the electrode.

As described above, according to this embodiment, it is possible to achieve both current collection, gas diffusion and drainage.

In Table 1, the ratio of the area where the separator is in close contact with the electrode (that is, the area of the convex portion) (area ratio of the current collecting portion),
Boundary layer prevention area (Figs. 4 (A) and 4 (B))
The number of parts corresponding to the positions PA1, PA2, PB1, PB2, etc.) (the number of boundary layer prevention parts) is shown.

[0037]

[Table 1]

Example 1 corresponds to the present embodiment (FIG. 1), and Examples 2 and 3 are second and third, which will be described later.
This corresponds to the embodiment. Conventional example 1 is shown in FIG.
The conventional example 2 corresponds to the separator shown in FIG. 13 and the separator shown in FIG. The comparative example corresponds to the separator shown in FIG. The current collector area ratio is
As shown in FIG. 7, it is calculated by the ratio of the total area of the convex portions to the area of the midstream portion of the meandering channel.

The first embodiment is the conventional example 1 in terms of the area ratio of the current collecting portion.
In comparison with the comparative example, the number of boundary layer prevention sites far exceeds the conventional example 1 and the comparative example. In Conventional Example 2, the number of boundary layer prevention sites is large, but the current collector area ratio is halved.

(Second Embodiment) FIG. 8 shows a main part of a separator according to a second embodiment of the present invention. In the first embodiment, in the upstream part, the midstream part and the downstream part of the meandering flow path, the convex parts forming the linear part of the flow path groove are replaced with another configuration, which is different from the first embodiment. I will explain mainly.
For convenience of description, in the description of the same parts as those in the first embodiment, the same numbers as those in the first embodiment are used.

Also in the present separator 11A, the convex portions 45 and 46 are arranged in parallel in parallel with the flow passage forming ribs 411 and 412, and the linear portions 531 forming the flow passage grooves 53 are formed on both sides thereof. The long side length is different between the convex portion 45 on one side edge side of the flow path groove linear portion 531 and the convex portion 46 on the other side edge side of the convex portion 45 of the longer side. The arrangement pitch in the column direction is four times the arrangement pitch in the column direction of the convex portions 46 whose shorter sides are shorter. As a result, one side edge side of the flow path groove linear portion 531 is provided with the convex portion discontinuous portion 45.
Even if it is a, the other side edge side is the convex discontinuous portion 46a.
Is once in four times, and the flow path groove linear portion 53
The convex discontinuity portion 45a on one side edge side and the convex discontinuity portion 46a on the other side edge side hardly overlap each other. That much
It is possible to improve gas diffusibility and drainage without impairing current collection.

If the convex portion 45 and the convex portion 46 differ in the length of the long side and the arrangement pitch in the column direction as described above, the second embodiment is also compared with the comparative example. The boundary layer prevention site will be doubled. Therefore, Example 2
As shown in Table 1 above, the current collector area ratio is comparable to that of the conventional example and the comparative example, and the number of boundary layer prevention sites far exceeds those of the conventional example 1 and the conventional example 2.

In the illustrated example, the convex portion 45 having the longer long side is formed.
In the part where the convex discontinuous portion 45a in which the columns are cascaded produces the boundary layer preventing action, the convex discontinuous portion 45a and the convex discontinuous portion 4 are formed.
6a overlaps, but this overlap is, for example, 1/2 of the arrangement pitch in the column direction of the convex portion 46 having the shorter long side, the convex portion 45 having the longer long side and the convex portion having the shorter long side. This can be solved by arranging so as to offset with 46.

The ratio of the arrangement pitches of the two types of convex portions having different long sides is not limited to 1: 4, but may be any ratio.

(Third Embodiment) Even when the arrangement of the convex portions of the separator is the same as that of the comparative example, the gas diffusibility can be improved by changing the shape of the convex portions which define the linear portions of the flow channel. FIG. 9 shows an enlarged view of the separator according to the present embodiment. The entire shape of the convex portion 47 that defines the linear portion 541 of the flow channel 54 of the separator 11B is equivalent to that of the comparative example. A step 4701a is formed on the long side surface 4701 of the convex portion 47 at a middle position in the longitudinal direction, and the width of the convex portion 47 is narrowed. The half of the side surface 4701 on the lower step side is inclined toward the corner of the convex portion 47 so that the width is restored. That is, the convex side surface 4701, which is the side wall surface of the flow channel linear portion 541, has a stepped shape that repeats unevenness in the lengthwise direction of the flow channel linear portion 541 with the convex discontinuous portion 47a interposed therebetween. Has become.

The gas flowing through the straight portion 541 of the flow channel is
In addition to the convex discontinuous portion 47a, the flow is disturbed in the step 4701a formed on the convex side surface 4701.

Therefore, the flow path groove linear portion 541 is
The position of the step 4701a on the side surface 4701 of the convex portion is also a boundary layer preventing portion similarly to the position where the side wall is interrupted by the discontinuous portion 47a of the convex portion, and gas diffusion and drainage are improved by the provision of the step 4701a.

If the convex side surface 4701 is provided with a step 4701a as the third embodiment, the boundary layer preventing portion of the third embodiment is doubled as compared with the comparative example. Therefore,
As shown in Table 1 above, Example 3 is comparable to the conventional example 1 and the comparative example in the area ratio of the current collecting portion, and far exceeds the conventional example 1 and the comparative example in the number of boundary layer prevention sites.

A step 4701a on the side surface 4701 of the convex portion 4701a
May be formed on the other side facing away. Also,
The shape of the side surface is not limited to that shown in FIG. For example, as shown in FIG. 10, the side surface 4801 of the convex portion 48 may be parallel to the stepped portion and the stepped portion of the step 4801a.

The characteristic part of this embodiment can be applied to the convex portions of the first and second embodiments, and the gas diffusibility and drainage can be further improved.

(Fourth Embodiment) FIG. 11 shows another embodiment in which the arrangement of the convex portions of the separator is a comparative example and the gas diffusivity and drainage are improved. The figure shows the upstream, middle and downstream parts of the meandering flow path. For convenience of description, in the description of the same parts as those in the first embodiment, the same numbers as those in the first embodiment are used.

The flow path groove linear portion 5 of the present separator 11C
The convex portion 49 defining 51 is the same as that of the comparative example. Further, on the bottom surface 5501 of the flow path groove linear portion 551, steps 5501a are provided at an interval of ½ of the arrangement pitch in the column direction of the protrusions 49 arranged in the column, and the saw tooth shape is formed in the column direction of the protrusions 49. It has a stepped shape that repeats unevenness.

The flow of the gas flowing into the flow path groove linear portion 551 is disturbed at each position of the steps 5501a formed on the bottom surface 5501. Therefore, the flow path groove straight line portion 551 is also a boundary layer preventing portion at the position of the step 5501a as well as the position where the side wall is interrupted by the convex discontinuous portion 49a, and the step 5501a is provided, so that the gas diffusivity and drainage are increased. The property is improved.

The characteristic part of this embodiment is applied to the bottom surface of the flow channel groove of the first, second, and third embodiments to which the characteristic parts of the first, second, third, and third embodiments are applied. It is possible to improve gas diffusibility and drainage.

[Brief description of drawings]

FIG. 1 is a plan view of a fuel cell separator according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part of a fuel cell to which the fuel cell separator is applied.

FIG. 3 is a plan view of a fuel cell separator for comparison with the fuel cell separator.

4A is an enlarged view of FIG. 1, and FIG. 4B is an enlarged view of FIG.

FIG. 5 is a graph showing a flow velocity distribution in a flow channel.

FIG. 6 is a diagram illustrating a flow velocity distribution in the flow channel.

FIG. 7 is a diagram illustrating Table 1.

FIG. 8 is a plan view of an essential part of a fuel cell separator according to a second embodiment of the present invention.

FIG. 9 is a plan view of an essential part of a fuel cell separator according to a third embodiment of the present invention.

FIG. 10 is a plan view of a main part of a modified example of the fuel cell separator.

FIG. 11A is a plan view of an essential part of a fuel cell separator according to a fourth embodiment of the present invention, and FIG.
3 is a cross-sectional view taken along line XIB-XIB in FIG.

FIG. 12 is a plan view of a typical example of a conventional fuel cell separator.

FIG. 13 is a plan view of another typical example of a conventional fuel cell separator.

[Explanation of symbols]

11, 11A, 11B, 11C Separator 12 Battery cell 120 Electrolyte membrane 121, 122 Electrode 1101, 1102 Surface 21 Fuel gas introducing hole 23 Oxidizing gas discharging hole 24 Oxidizing gas introducing hole 26 Fuel gas discharging hole 22, 25 Cooling water flow path hole 31 , 32 flow path 311 upstream part 312 folding part 313 middle part 314 folding part 315 downstream part 41 frame-shaped convex part 411, 412 flow path forming ribs 42, 43, 44, 45, 46, 47, 48, 49 convex part 42a , 43a, 45a, 46a, 47a, 49a Convex portion discontinuous portion 4701, 4801 Side surface 4701a, 4801a Steps 51, 52, 53, 54 Flow channel grooves 511, 531, 541, 551 Flow channel linear portion 5501 Bottom surface 5501a Step

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Fumiya Nagai             14 Iwatani Shimohakaku-cho, Nishio-shi, Aichi Stock Association             Company Japan Auto Parts Research Institute (72) Inventor Toshiyuki Suzuki             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Tsuyoshi Takahashi             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. F-term (reference) 5H026 AA01 CC03 CC04

Claims (4)

[Claims] 1. A separator forming a partition wall of battery cells stacked in a fuel cell, the surface of which is provided with a convex portion that is in contact with an electrode of the battery cell to conduct electricity, and is supplied to the electrode by a convex portion non-forming portion. In the fuel cell separator, a flow channel groove is formed in which a fuel gas or an oxidizing gas that flows flows through a gap between the electrode and the flow channel groove, and the flow channel groove includes a plurality of linear portions that are parallel to each other. As the convex portion arranged along the portion, a rectangular convex portion having a long side that defines the side edge of the linear portion, and provided with a plurality of convex portions arranged in a row along the linear portion, Further, the fuel cell separator is characterized in that a convex portion is formed asymmetrically on one side edge side and the other side edge side of the flow path groove linear portion. 2. The fuel cell separator according to claim 1, wherein the protrusions arranged along the straight line portion of the flow channel groove have a single shape, and the plurality of columnarly disposed protrusions are formed in the flow channel. A fuel cell separator in which a convex portion formed on one side edge side of a groove linear portion and a convex portion formed on the other side edge side are arranged to be offset in the column direction. 3. The fuel cell separator according to claim 1, wherein the plurality of vertically arranged convex portions are formed such that the lengths of their long sides are on one side edge side of the flow path groove linear portion. A fuel cell separator having different shapes for a convex portion and a convex portion formed on the other side edge side. 4. A separator forming a partition wall of battery cells stacked in a fuel cell, the surface of which is provided with a convex portion that is in contact with and electrically connected to the electrode of the battery cell, and is supplied to the electrode by the convex portion non-forming portion. In the fuel cell separator, a flow channel groove is formed in which a fuel gas or an oxidizing gas that flows flows through a gap between the electrode and the flow channel groove, and the flow channel groove includes a plurality of linear portions that are parallel to each other. A fuel cell separator, wherein a side surface or a bottom surface of the portion has a stepped shape in which unevenness is repeated in the lengthwise direction of the linear portion.