JP6454904B2 - Gas flow path forming plate for fuel cell and fuel cell stack - Google Patents

Description

  The present invention is formed by laminating a plurality of gas flow path forming plates that are interposed between a membrane electrode assembly and a flat flat separator to constitute a single cell separator of a fuel cell, and a plurality of the single cells. The present invention relates to a fuel cell stack.

  For example, a polymer electrolyte fuel cell includes a fuel cell stack formed by stacking a plurality of single cells each including a membrane electrode assembly and a pair of separators sandwiching the membrane electrode assembly.

  As such a separator, there is one having a flat flat separator and a gas flow path forming plate interposed between the membrane electrode assembly and the flat separator (for example, see Patent Document 1).

  A plurality of concave grooves extending in parallel to each other are formed on a surface of the gas flow path forming plate facing the membrane electrode assembly, and the concave grooves form a gas flow path for circulating fuel gas or oxidant gas. Is done. Further, protrusions are formed between two adjacent gas flow paths in the gas flow path forming plate, and a plurality of concave grooves are formed on the back surfaces of these protrusions. This concave groove serves as a water flow path for discharging water generated with power generation. In addition, a communication path that connects the gas flow path and the water flow path is formed in the protrusion.

  In such a fuel cell stack, water generated with power generation in the membrane electrode assembly flows into the gas flow path of the gas flow path forming plate, and flows into the water flow path through the communication path. Then, the fuel gas or oxidant gas (hereinafter referred to as gas) flowing through the water channel is discharged to the outside of the water channel.

Japanese Patent Laid-Open No. 2015-15218

  By the way, in such a conventional gas flow path forming plate, in the power generation state where the gas flow rate is low, the flow of the oxidant gas becomes a laminar flow. It is difficult to mix things that flow on the body side. For this reason, among the gas flowing in the gas flow path, the gas flowing on the membrane electrode assembly side is introduced into the membrane electrode assembly and used for power generation, but the gas flowing on the flat separator side is difficult to be introduced into the membrane electrode assembly. It is difficult to be used for power generation. As a result, the power generation efficiency is low.

  An object of the present invention is to provide a fuel cell gas flow path forming plate and a fuel cell stack capable of improving power generation efficiency even in a power generation state with a low gas flow rate.

  A fuel cell gas flow path forming plate for achieving the above object is formed of a metal plate material, and is interposed between a membrane electrode assembly and a flat flat separator to constitute a single cell separator of a fuel cell. A plurality of groove-shaped gas passages formed on a surface facing the membrane electrode assembly and extending in parallel with each other, and protrusions positioned between two adjacent gas passages. A plurality of groove-shaped water flow paths formed on the back surface of the gas flow path, and a plurality of communication paths that connect the gas flow paths and the water flow paths are formed on the ridges. On the bottom surface, there is formed a guide portion that protrudes toward the downstream side in the flow direction of the gas flowing through the gas flow path and guides the gas toward the membrane electrode assembly.

  A fuel cell stack for achieving the above object is formed by stacking a plurality of single cells, and the single cell sandwiches the membrane electrode assembly and the membrane electrode assembly. A pair of separators, and one of the separators includes the flat separator and the fuel cell gas flow path forming plate interposed between the membrane electrode assembly and the flat separator. .

  According to this configuration, the gas that flows in the vicinity of the bottom surface of the gas flow path flows along the guide portion, and is thus guided toward the membrane electrode assembly. For this reason, even in the power generation state where the gas flow rate is low, more gas is introduced into the membrane electrode assembly and used for power generation.

  According to the present invention, power generation efficiency can be improved even in a power generation state where the gas flow rate is low.

Sectional drawing of a fuel cell stack about one Embodiment of the gas flow path formation board for fuel cells, and a fuel cell stack. The perspective sectional view of the 1st separator in the embodiment. The elements on larger scale of FIG. (A) is the fragmentary sectional view along the aa line of FIG. 3, (b) is the fragmentary sectional view along the bb line of FIG. (A), (b) is a schematic diagram of a gas flow path and a communicating path. (A)-(d) is sectional drawing centering on a communicating path, Comprising: Explanatory drawing explaining the effect | action of the same embodiment. The expanded sectional view centering on the gas flow path of the oxidizing gas of FIG. The expanded sectional view centering on the gas flow path of the oxidizing agent gas in a modification.

Hereinafter, an embodiment will be described with reference to FIGS.
As shown in FIG. 1, the solid polymer fuel cell includes a fuel cell stack formed by stacking a plurality of single cells 10. In the figure, the upper unit cell 10 has a cross-sectional shape cut at a position where water channels 26 and 36 described later are shown, while the lower unit cell 10 includes gas channels 25 and 35 described later. The cross-sectional shape cut | disconnected in the position shown is shown.

  Each unit cell 10 includes a first frame 11 and a second frame 12 each having a rectangular frame shape, and the outer edge portion of a known membrane electrode assembly 13 having a rectangular sheet shape is sandwiched between the frames 11 and 12. Has been.

  The membrane electrode assembly 13 includes a solid polymer electrolyte membrane 14, and the solid polymer electrolyte membrane 14 is sandwiched between well-known electrode catalyst layers 15 and 16. Further, well-known gas diffusion layers 17 and 18 are provided on the surfaces of the electrode catalyst layers 15 and 16, respectively.

The membrane electrode assembly 13 is sandwiched by the first separator 20 and the second separator 30 from the cathode side (lower side in the figure) and the anode side (upper side in the figure), respectively.
The first separator 20 includes a flat flat separator 21 and a gas flow path forming plate 22 interposed between the flat separator 21 and the membrane electrode assembly 13.

The second separator 30 includes a flat flat separator 31 and a gas flow path forming plate 32 interposed between the flat separator 31 and the membrane electrode assembly 13.
The flat separators 21 and 31 and the gas flow path forming plates 22 and 32 are each formed of a metal plate material.

  By the first frame 11 and the flat separator 21, a supply passage 41 for supplying an oxidant gas from an oxidant gas supply source (not shown) to a gas passage 25 described later, and an oxidant gas that has not been used for power generation are gasified. A discharge passage 42 for discharging to the outside of the flow path 25 is formed.

  Further, the second frame 12 and the flat separator 31 are used to supply a fuel gas from a fuel gas supply source (not shown) to a gas flow path 35 described later, and a fuel gas that has not been used for power generation is supplied to the gas flow. A discharge passage 52 for discharging to the outside of the path 35 is formed.

  In the portion shown in FIG. 1, the gas flow path forming plate 32 of the second separator 30 has a shape that is vertically reversed and horizontally reversed with respect to the gas flow path forming plate 22 of the first separator 20. Therefore, hereinafter, the gas flow path forming plate 22 of the first separator 20 will be described, and the gas flow path forming plate 32 of the second separator 30 will be denoted by the reference numerals of the respective parts of the gas flow path forming plate 22 of the first separator 20. A duplicate description is omitted by adding a symbol “3 *” obtained by adding “10” to “2 *”. In addition, redundant description is omitted by adding “37 *” and “38 *” obtained by adding “100” to “27 *” and “28 *”, respectively.

Next, the structure of the gas flow path forming plate 22 will be described.
As shown in FIG. 2, the gas flow path forming plate 22 has a substantially corrugated cross section, and is formed, for example, by roll forming a single metal plate material such as a stainless steel plate. A plurality of inner ridges 23 extending in parallel to each other are formed on the upper surface of the gas flow path forming plate 22, and the top surface of the inner ridge 23 is in contact with the membrane electrode assembly 13. In addition, a plurality of gas flow paths 25 are formed between the two adjacent inner ridges 23 to form a concave groove and allow the oxidant gas to flow therethrough.

  A plurality of outer ridges 24 extending in parallel to each other are formed on the lower surface of the gas flow path forming plate 22, and the top surface of the outer ridge 24 is in contact with the flat separator 21. In addition, a plurality of water flow paths 26 are formed on the back surface of the inner ridge 23, each of which has a concave groove shape and discharges water generated with power generation in the membrane electrode assembly 13. Accordingly, the outer ridge 24 is located between two adjacent water flow paths 26 and defines the two water flow paths 26.

  As shown in FIGS. 2 to 4, in the gas flow path forming plate 22, the extending direction of the protrusions 23, 24, that is, the extending direction of the gas flow path 25 (hereinafter simply referred to as the extending direction L). A plurality of ribs 271 extending along a direction orthogonal to the direction (hereinafter referred to as the width direction W) are formed.

  As shown in FIG. 2, each gas flow path 25 is formed with a plurality of pairs each formed of a pair of ribs 271 formed close to each other in the extending direction L. The sets of the pair of ribs 271 are provided at equal intervals in the extending direction L. The plurality of ribs 271 are formed by partially bending the protrusions 23 and 24 when the gas flow path forming plate 22 is formed by roll forming a metal plate along the width direction W. It is formed.

  As shown in FIGS. 2 to 4, the plurality of ribs 271 are formed on the inner ridge 23 of the gas flow path forming plate 22, thereby connecting a plurality of communication channels that connect the gas flow path 25 and the water flow path 26. A passage 27 is formed. As shown in FIGS. 4A and 4B, the ribs 271 protrude into the gas channel 25 and the water channel 26, respectively. As shown in FIGS. 2 to 4, the outer ridge 24 is formed with a communication groove 272 that connects the water flow paths 26 adjacent to each other.

  The rib 271 is closer to the top surface of the outer ridge 24 than the top surface of the inner ridge 23 in the thickness direction of the gas flow path forming plate 22 (vertical direction in FIGS. 4A and 4B). Is provided. For this reason, the cross-sectional area of the portion of the rib 271 that blocks the water flow path 26 is larger than the cross-sectional area of the portion that blocks the gas flow path 25. Therefore, even if the channel cross-sectional area of the gas channel 25 and the channel cross-sectional area of the water channel 26 at the position where the rib 271 does not exist in the extending direction L are set to be the same, the pressure loss in the entire water channel 26 is The pressure loss in the entire gas flow path 25 becomes larger. The shape and size of the communication path 27 are set so that the pressure loss in the communication path 27 is larger than the pressure loss in the gas flow path 25. For these reasons, the oxidant gas mainly flows through the gas flow path 25 with a small pressure loss.

  As shown in FIGS. 1, 2, and 7, a plurality of guide portions 28 are integrally formed on the bottom surface of the gas flow path 25. Each guide portion 28 protrudes toward the downstream side in the flow direction of the oxidant gas flowing through the gas flow path 25 (hereinafter simply referred to as “downstream side”), and guides the gas toward the membrane electrode assembly 13.

  As shown in FIG. 2, each guide portion 28 has the same shape and the same size, and the inner ridge 23 adjacent to the gas flow path 25 in which the guide portion 28 is formed is connected. It is formed so as to be adjacent to the passage 27 in the width direction W. Accordingly, the guide portions 28 are also provided at equal intervals in the extending direction L, similarly to the communication passage 27.

  As shown in FIG. 7, the guide portion 28 is formed at a position closer to the top surface of the outer protrusion 24 than an intermediate position in the thickness direction of the gas flow path forming plate 22 (vertical direction in the figure). The inclined surface 281 is inclined so as to protrude toward the downstream side.

  The plurality of guide portions 28 are formed by being subjected to shear bending when forming the gas flow path forming plate 22 by roll forming a metal plate material along the width direction W in the same manner as the ribs 271. . A communication hole 29 that connects the gas flow path 25 and the water flow path 26 is formed on the downstream side of the guide portion 28. The communication hole 29 is formed when the guide portion 28 is formed.

Next, the operation of this embodiment will be described.
As shown in the lower unit cell 10 in FIG. 1, when the fuel gas is supplied into the gas flow path 35 through the supply passage 51, the fuel gas flows into the gas diffusion layer 18 through the gas flow path 35. The fuel gas passes through the gas diffusion layer 18 and is diffused and supplied to the electrode catalyst layer 16.

  When the oxidant gas is supplied into the gas flow path 25 through the supply passage 41, the oxidant gas flows into the gas diffusion layer 17 through the gas flow path 25. The oxidizing gas passes through the gas diffusion layer 17 and is diffused and supplied to the electrode catalyst layer 15.

When the fuel gas and the oxidant gas are respectively supplied to the membrane electrode assembly 13 in this way, electric power is generated by an electrochemical reaction in the membrane electrode assembly 13.
In the present embodiment, as shown in FIGS. 1 and 7, the oxidant gas flowing near the bottom surface of the gas flow path 25 flows along the guide portion 28, thereby being guided toward the membrane electrode assembly 13. For this reason, even in a power generation state in which the flow rate of the oxidant gas is small, more oxidant gas is introduced into the membrane electrode assembly 13 and used for power generation.

  Further, as shown in FIG. 1, the fuel gas that flows in the vicinity of the bottom surface of the gas flow path 35 flows along the guide portion 38 and is guided toward the membrane electrode assembly 13. For this reason, even in the power generation state where the flow rate of the fuel gas is small, more fuel gas is introduced into the membrane electrode assembly 13 and used for power generation.

  Incidentally, as shown in FIG. 7, a corner portion 251 in which the oxidant gas does not flow easily is formed on the downstream side of the guide portion 28 in the gas flow path 25, so that it is generated along with power generation in the membrane electrode assembly 13. Water S tends to stay in the corner 251. In this regard, according to the present embodiment, the water S in the gas flow path 25 moves to the water flow path 26 through the communication hole 29.

At this time, the water generated by the power generation mainly flows into the gas flow path 25 of the gas flow path forming plate 22 on the cathode side.
5A and 5B, a part of this water flows in the gas flow path 25 due to the flow pressure of the oxidant gas flowing in the gas flow path 25. . And water is discharged | emitted outside through the discharge channel | path 42 (refer FIG. 1). As described above, the pressure loss in the communication passage 27 is larger than the pressure loss in the gas flow path 25. For this reason, as shown in FIG. 5B, the oxidant gas mainly flows through the gas flow path 25. Thereby, most of the water S present in the gas flow path 25 moves in the gas flow path 25 toward the discharge passage 42 while being pushed by the oxidant gas. Further, as shown by thin arrows in FIG. 5B, a part of the water is introduced into the water flow path 26 through the communication path 27. In addition, illustration of the guide part 28 is abbreviate | omitted in FIG.

  At this time, the water introduced into the water channel 26 becomes water droplets by the surface tension acting according to the opening area of the outlet opening of the water channel 26. When the water flow path 26 is in a wet state, when the water droplets S are moored to the ribs 271, the water in the water flow path 26 becomes the priming water, and the water in the communication path 27 is guided into the water flow path 26 by capillary action and is described above. It is discharged through the outlet opening.

  Further, when there is no dry water in the water flow path 26, as shown in FIG. 6 (a), water is connected to the top surface of the inner ridge 23 in contact with the gas diffusion layer 17, as shown in FIG. The water droplets S1 and S2 are formed by being guided into the passage 27 by capillary action.

  Then, when the water droplets S1 and S2 grow as water is further guided, both the water droplets S1 and S2 are combined into one water droplet S3, as shown in FIG. 6B. Immediately after this combination or when the water droplet S3 further grows, the water droplet S3 comes into contact with the rib 271. When the water droplet S3 reaches the gap between the pair of ribs 271 as shown in FIG. 6 (c), the water droplet S3 is drawn into the gap by capillary action as shown in FIG. 6 (d). It is introduced into the passage 26.

  Further, part of the water generated as a result of power generation flows into the gas flow path 35 of the gas flow path forming plate 32 through the electrode catalyst layer 16 and the gas diffusion layer 18 on the anode side (upper side in FIG. 1). In the present embodiment, the anode-side gas flow path forming plate 32 has basically the same configuration as the cathode-side gas flow path forming plate 22, and therefore, in the anode-side gas flow path 35 and the water flow path 36 as well. The same action as the cathode side gas passage 25 and the water passage 26 is exhibited.

According to the fuel cell gas flow path forming plate and the fuel cell stack according to the present embodiment described above, the following effects can be obtained.
(1) Guide portions 28 and 38 are integrally formed on the bottom surfaces of the gas flow paths 25 and 35 so as to protrude toward the downstream side and guide the oxidant gas and the fuel gas toward the membrane electrode assembly 13, respectively. For this reason, even in the power generation state where the flow rates of the oxidant gas and the fuel gas are low, more oxidant gas and fuel gas are introduced into the membrane electrode assembly 13 and used for power generation. Become. Therefore, the power generation efficiency can be improved even in the power generation state where the flow rates of the oxidant gas and the fuel gas are small.

  (2) The gas flow path forming plates 22 and 32 were formed by roll forming metal plate materials along the width direction W orthogonal to the extending direction L of the gas flow paths 25 and 35, respectively. Further, the guide portions 28 and 38 are formed so as to be adjacent to the communication passages 27 and 37 of the inner ridges 23 and 33 adjacent to the gas flow paths 25 and 35 in which the guide portions 28 and 38 are formed, respectively.

  The roll forming apparatus includes a pair of rolls in which a plurality of cutting blades are stacked in the axial direction (not shown). According to the said structure, only by adding the shape corresponding to the guide part 28 (38) to the cutting blade which each forms the communicating path 27 (37) among several cutting edges which comprise each roll, the communicating path 27 ( 37) can be formed. Therefore, the gas flow path forming plates 22 and 32 can be manufactured only by changing the shape of a part of the plurality of cutting blades constituting the existing roll.

  (3) Since the inclined surfaces 281 and 381 that are inclined so as to protrude toward the downstream side with respect to the guide portions 28 and 38 are provided, the oxidant gas and the fuel gas flow smoothly along the inclined surfaces 281 and 381, respectively. become. For this reason, it is possible to suppress an increase in pressure loss of the oxidant gas or the fuel gas accompanying the addition of the guide portions 28 and 38 to the gas flow paths 25 and 35.

  (4) Corner portions 251 and 351 are formed on the downstream side of the guide portions 28 and 38 in the gas flow paths 25 and 35 as the guide portions 28 and 38 are integrally formed. In the corners 251 and 351, communication holes 29 and 39 for communicating the gas flow paths 25 and 35 and the water flow paths 26 and 36 were formed, respectively.

  According to such a configuration, the water S in the gas flow paths 25 and 35 moves to the water flow paths 26 and 36 through the communication holes 29 and 39. Therefore, water can be prevented from staying in the corners 251 and 351 of the gas flow paths 25 and 35.

<Modification>
In addition, the said embodiment can also be changed as follows, for example.
The gas flow path forming plates 22 and 32 may be formed of a metal plate material other than a stainless steel plate such as a titanium plate.

The guide portions 28 and 38 can be formed so that the communication holes 29 and 39 are not formed.
For example, as shown in FIG. 8, the guide part 128 can also be formed in a step shape so as to protrude toward the downstream side. In this case, in the same manner as in the above-described embodiment, the oxidant gas flowing near the bottom surface of the gas flow path 125 flows along the guide portion 128 and is guided toward the membrane electrode assembly 13. For this reason, even in a power generation state in which the flow rate of the oxidant gas is small, more oxidant gas is introduced into the membrane electrode assembly 13 and used for power generation. In addition, about the structure corresponding to the 1st separator 20 of the said embodiment among the structures of the 1st separator 120, the code | symbol "12 *" which added "100" to the code | symbol "2 *" of the structure of the 1st separator 20, respectively. The description which overlaps by omitting is omitted.

The guide part 28 is not limited to be formed adjacent to the communication path 27, and the guide part 28 can be formed at a position different from the communication path 27 in the extending direction L.
In the above-described embodiment, the guide portions 28 and 38 are provided at equal intervals in the extending direction L. However, the guide portions 28 and 38 are arranged more downstream than the upstream side of the gas flow paths 25 and 35. May be. In the gas flow paths 25 and 35, the gas is consumed in order from the upstream side, so that the gas is reduced toward the downstream side. In this regard, if more guide portions 28 and 38 are arranged on the downstream side of the gas flow paths 25 and 35, the downstream side of the gas flow paths 25 and 35 in which gas is not easily introduced into the membrane electrode assembly 13. Also, a larger amount of gas is introduced into the membrane electrode assembly 13. Further, on the upstream side of the gas flow paths 25 and 35, since the guide portions 28 and 38 are disposed relatively few, the pressure loss of the gas increases due to the addition of the guide portions 28 and 38. It can be suppressed appropriately.

  In the above-described embodiment, each of the guide portions 28 and 38 has the same shape and the same size, but the shape and size of the plurality of guide portions can be made different depending on the position.

  In the above-described embodiment, the gas flow path forming plates 22 and 32 having the guide portions 28 and 38 are provided on both the cathode side and the anode side of the membrane electrode assembly 13. The gas flow path forming plate 22 having the guide portion 28 may be provided only on the cathode side of the body 13, and the gas flow path forming plate having no guide portion may be provided on the anode side. Moreover, the separator which does not have a communicating hole can also be arrange | positioned at the anode side.

  Alternatively, the gas flow path forming plate 32 may be provided only on the anode side of the membrane electrode assembly 13, and the gas flow path forming plate having no guide portion may be provided on the cathode side.

  DESCRIPTION OF SYMBOLS 10 ... Single cell, 11 ... 1st frame, 12 ... 2nd frame, 13 ... Membrane electrode assembly, 14 ... Solid polymer electrolyte membrane, 15, 16 ... Electrode catalyst layer, 17, 18 ... Gas diffusion layer, 20 ... 1st separator, 21 ... flat separator, 22 ... gas flow path forming plate, 23 ... inner ridge, 24 ... outer ridge, 25 ... gas flow path, 251 ... corner, 26 ... water flow path, 27 ... communication path, 271 ... Rib, 272 ... Communication groove, 28 ... Guide part, 281 ... Inclined surface, 29 ... Communication hole, 30 ... Second separator, 31 ... Flat separator, 32 ... Gas flow path forming plate, 33 ... Inner ridge, 34 ... outer ridge, 35 ... gas flow path, 351 ... corner, 36 ... water flow path, 37 ... communication path, 371 ... rib, 372 ... communication groove, 38 ... guide section, 381 ... inclined surface, 39 ... communication hole, 41 ... Supply passage, 42 ... Discharge passage, 51 ... Supply passage, 5 ... supply passage.

Claims (5)

A gas flow path forming plate formed of a metal plate material and interposed between a membrane electrode assembly and a flat flat separator to constitute a single cell separator of a fuel cell,
A plurality of groove-shaped gas flow paths formed on a surface facing the membrane electrode assembly and extending in parallel with each other;
A plurality of groove-shaped water flow paths formed on the back surface of the ridge located between two adjacent gas flow paths,
A plurality of communication passages that connect the gas flow path and the water flow path are formed in the ridge,
A guide portion is formed on the bottom surface of the gas flow path so as to protrude toward the downstream side in the flow direction of the gas flowing through the gas flow path, and to guide the gas toward the membrane electrode assembly .
A corner portion is formed on the downstream side of the guide portion in the gas flow path as the guide portion is integrally formed,
The corner is formed with a communication hole that communicates the gas flow path and the water flow path.
A fuel cell gas flow path forming plate. The gas flow path forming plate is formed by roll forming a metal plate material along a direction orthogonal to the extending direction of the gas flow path,
The guide part is formed so as to be adjacent to the communication path of the ridge adjacent to the gas flow path in which the guide part is formed.
The gas flow path forming plate for a fuel cell according to claim 1. The guide portion has an inclined surface that is inclined so as to protrude toward the downstream side in the flow direction of the gas flowing through the gas flow path.
The gas flow path forming plate for a fuel cell according to claim 1 or 2. The guide part is formed in a stepped shape so as to protrude toward the downstream side in the flow direction of the gas flowing through the gas flow path.
The gas flow path forming plate for a fuel cell according to claim 1 or 2. A fuel cell stack formed by stacking a plurality of single cells,
The single cell includes a membrane electrode assembly and a pair of separators sandwiching the membrane electrode assembly,
The said one separator is the gas separator formation for fuel cells as described in any one of Claims 1-4 interposed between the said flat separator, the said membrane electrode assembly, and the said flat separator. A board,
Fuel cell stack.