JP2006202570A - Fuel cell and fuel cell distribution plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell capable of contributing to the uniformity of current density distribution at a power generating area by enhancing the uniformity of water distribution caused by the unevenness of generated water, and to provide a fuel cell distribution plate. <P>SOLUTION: The fuel cell is provided with a film-electrode assembly composed of an electrolyte film, and a fuel electrode and an oxidant electrode interposing the electrolyte film; the fuel side distribution plate having a fuel flow passage supplying fuel to the fuel electrode; and an oxidant side distribution plate having an oxidant floe passage supplying an oxidant to the oxidant electrode. At least either the fuel flow passage 42 on the fuel side distribution plate or the oxidant flow passage on the oxidant side distribution plate is curved. On condition that a projection area of the power generation area is 100%, a counter flow area where the flowing direction of the fuel flowing through the fuel flow passage 42 and that of the oxidant flowing through the oxidant flow passage oppose each other occupies not less than 70% of the power generating area. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell having an oxidant gas passage and a fuel passage, and a fuel cell distribution plate used in the fuel cell.

  In Patent Document 1, an oxidant gas passage that extends straight in the vertical direction is formed in the first separator positioned so as to sandwich the electrolyte membrane, and a fuel gas passage that extends straight in the vertical direction is provided in the second separator. There has been disclosed a polymer electrolyte fuel cell in which the oxidant gas passage and the fuel gas passage of the second separator are set so that the flow directions of the oxidant gas and the fuel gas are opposed to each other. According to this document, it is described that it can contribute to uniform wetting of the electrolyte membrane.

  Similarly, in Patent Document 2, an oxidant gas passage is formed so as to extend straight in the vertical direction in the first separator positioned so as to sandwich the electrolyte membrane, and so as to extend straight in the vertical direction in the second separator. A fuel cell is disclosed in which a fuel gas passage is provided, and the flow direction of the oxidant gas and the flow direction of the fuel gas are set to face each other in the oxidant gas passage of the first separator and the fuel gas passage of the second separator. Has been.

Patent Document 3 discloses a fuel-side flow distribution plate having a serpentine type fuel passage formed along the vertical direction while meandering, and a serpentine type oxidant passage formed along the vertical direction while meandering. A fuel cell having an oxidant side flow distribution plate is disclosed.
JP 2003-242998 A JP 2004-185934 A JP 2004-119121 A

  By the way, in the fuel cell, it is important to make the distribution of generated water uniform. According to Patent Documents 1 and 2, since the oxidant gas passage is formed to extend straight, the generated water generated by the power generation reaction can be discharged well.

  However, since the gas passage is formed so as to extend straight, there is a possibility that the degree of freedom of the position where the gas inlet and outlet are arranged in the flow distribution plate may be limited. In particular, when air is used as the oxidant, the flow rate of the oxidant per unit time increases, so it is necessary to increase the opening area of the inlet and outlet. It is not preferable that the degree of freedom is restricted. Therefore, if the oxidant gas passage or the fuel passage has a bent passage, the degree of freedom described above can be increased by adjusting the bent state of the bent passage.

  However, the bent passage can increase the degree of freedom described above, but tends to contribute to non-uniform distribution of the generated water because it has higher resistance to discharge of generated water than the non-bent passage. If the distribution of generated water becomes non-uniform in this way, the smooth flow of oxidant gas and fuel is impaired, and this tends to cause non-uniform distribution of current density in the power generation region.

  The present invention has been made in view of the above-described circumstances, and in the method of forming a bent passage, the uniformity of the current distribution in the power generation region is improved by increasing the uniformity of the water distribution due to the non-uniformity of the generated water. It is an object of the present invention to provide a fuel cell and a fuel cell distribution plate that can contribute to the above.

A fuel cell according to the present invention includes an electrolyte membrane having ion conductivity, a membrane electrode assembly having a fuel electrode and an oxidizer electrode sandwiching the electrolyte membrane,
A fuel side distributor plate having a fuel passage for supplying fuel to the fuel electrode;
In a fuel cell comprising an oxidant side distribution plate having an oxidant passage for supplying an oxidant to an oxidant electrode,
At least one of the fuel passage of the fuel side distribution plate and the oxidant passage of the oxidant side distribution plate has a bent passage; and
When the projected area projected onto the electrolyte membrane in the power generation region where the fuel electrode and the oxidizer electrode face each other with the electrolyte membrane interposed therebetween is 100%, the direction of the fuel flowing through the fuel passage and the direction of the oxidizer flowing through the oxidizer passage The projected area of the counterflow region with the opposite direction occupies 70% or more.

  A fuel cell distribution plate according to the present invention supplies a fuel or an oxidant to a fuel electrode or an oxidant electrode constituting a membrane electrode assembly, and has a bent passage, and a projected area of a power generation region in the fuel cell distribution plate Is 100%, the projected area of the counterflow region in which the fuel flow direction and the oxidant flow direction are opposite to each other occupies 70% or more of the power generation region.

  At least one of the fuel passage of the fuel side distribution plate and the oxidant passage of the oxidant side distribution plate has a bent passage. The bent passage tends to be a resistance of the flow of generated water, easily causes a non-uniform distribution of the generated water, and tends to make a non-uniform distribution of current density.

  In this regard, according to the present invention, when the projected area of the power generation region is 100%, the projection of the counter flow region in which the direction of the fuel flowing through the fuel passage and the direction of the oxidant flowing through the oxidant passage are opposite to each other is projected. The area is set to occupy 70% or more of the power generation region. The counterflow region is a region in which the fuel flow direction and the oxidant flow direction are opposite to each other. In such a counterflow region, the upstream of the oxidant passage corresponds to the downstream of the fuel passage, and the downstream of the oxidant passage corresponds to the upstream of the fuel passage.

  In the counterflow region, the flow direction of the fuel flowing through the fuel passage and the direction of the oxidant flowing through the oxidant passage are opposite to each other. Here, if the area of the counterflow region is less than 70% of the power generation region, sufficient water dispersion action cannot be obtained. In order to obtain a good water dispersing action, it is preferable that the counterflow region occupies 80% or more, 90% or more, 95% or more, 98% or more, or 100% of the power generation region.

  Since the area of the counterflow region occupies a considerable amount in this way, when the water accumulated downstream of the oxidant passage penetrates the electrolyte membrane and moves to the fuel passage side, the fuel flowing through the fuel passage converts water into the downstream side of the fuel passage, That is, it can be shifted to the upstream side of the oxidant passage. That is, the water dispersing action can be exhibited well. As a result, it is possible to suppress the occurrence of non-uniform water distribution in the power generation region, to suppress the non-uniformity of the current density distribution due to the non-uniformity of the generated water distribution, and to improve the power generation performance. Can contribute.

  According to the fuel cell of the present invention, at least one of the fuel passage and the oxidant passage has a bent passage. For this reason, the freedom degree of the position which arrange | positions the inlet_port | entrance and exit of a fuel and the inlet_port | entrance and exit of an oxidizing agent can be raised. In particular, when air is used as the oxidant, the flow rate of the oxidant increases, so it is necessary to increase the opening area of the inlet and outlet of the oxidant. In this way, the opening area of the inlet and outlet is increased. Even in this case, if the oxidant passage or the fuel passage has a bent passage, the degree of freedom described above can be increased by adjusting the bent state of the bent passage.

  According to the fuel cell of the present invention, when the projected area of the power generation region is 100%, the flow direction of the fuel flowing through the fuel passage and the direction of the oxidant flowing through the oxidant passage are opposite to each other. The area is set to occupy 70% or more. Thus, the area of the counter flow region is considerably occupied in the power generation region. For this reason, when the water accumulated downstream of the oxidant passage penetrates the electrolyte membrane and moves to the fuel passage side, the fuel flowing through the fuel passage directs the water toward the downstream side of the fuel passage, that is, in the oxidant passage. It can be shifted toward the upstream side. Therefore, the water dispersing action can be exhibited well, and the uneven distribution of water can be suppressed.

  As a result, according to the fuel cell of the present invention, it is possible to suppress the occurrence of bias in the water distribution in the power generation region while having the bent passage that causes the uneven distribution of the water distribution. Power generation unevenness caused by distribution unevenness can be reduced. Therefore, the uniformity of the current density distribution when the power generation region generates power can be increased, the power generation efficiency can be increased, and the power generation performance of the fuel cell can be improved.

  The power generation region is a region where the fuel electrode and the oxidant electrode overlap. When the projected area of the power generation region is 100%, the area of the counter flow region where the direction of the fuel flowing upward in the fuel passage and the direction of the oxidant gas flowing downward in the oxidant passage is opposite is the power generation region Is set to occupy 70% or more, preferably 80% or more, 90% or more, 95% or more, or 98% or more. Note that the area of the counterflow region means the area of the flow channel region including the protrusion when the protrusion is provided on the flow distribution plate.

  As a result of the above, when water accumulated downstream of the oxidant passage penetrates the electrolyte membrane and moves to the fuel passage side, the fuel gas flowing through the fuel passage causes water to flow downstream of the fuel passage, that is, upstream of the oxidant passage. Can be migrated to. As a result, the occurrence of bias in the water distribution in the power generation region can be suppressed, the uniformity of the current density distribution when the power generation region generates power can be increased, and the power generation efficiency of the fuel cell can be increased. .

  According to the present invention, the basic flow direction of the oxidant flowing through the oxidant passage is a direction flowing from top to bottom, and the basic flow direction of the fuel flowing through the fuel passage is a direction flowing from bottom to top. Can be adopted. Since the generated water is generated at the oxidizer electrode, it is easy for flattening of water to close the gas passage in the oxidizer passage. However, as described above, the basic flow direction of the oxidizer is from the top to the bottom. It is advantageous for improving the water discharge performance utilizing gravity in the oxidant passage.

  According to the present invention, at least one of the fuel passage of the fuel side distribution plate and the oxidant passage of the oxidant side distribution plate can have a configuration having at least two bent passages. In this case, it is possible to adopt a configuration in which the power generation region where the fuel electrode and the oxidant electrode overlap is disposed between the bent passages. Here, the bent passage is likely to cause water non-uniformity, and hence the current density distribution non-uniformity. However, if the power generation region is arranged between the bent passages as described above, it is caused by water non-uniformity. This is advantageous in suppressing non-uniform current density distribution.

  A form provided in the counterflow region (only) can be adopted as the power generation region. As will be described in the examples described later, the projected shape of the fuel electrode is extended along the vertical direction, with the upper side portion inclined from one end to the other end, the lower side portion inclined in the same direction from one end to the other end, and the like. The projected shape of the oxidant electrode has an upper side portion inclined from one end to the other end and the same direction from one end to the other end so as to overlap with the projected shape of the fuel electrode. A form having an inclined lower side portion and opposite side portions extending along the vertical direction can be adopted.

  According to the present invention, each fuel passage has a first passage extending in the lateral direction from the fuel inlet and a second passage extending in the longitudinal direction while communicating with the first passage. When the overall width of the first passages constituting each fuel passage is LA and the overall width of the second passages constituting each fuel passage is LB, the configuration in which LA <LB is adopted is adopted. be able to.

  According to the present invention, the fuel passage of the fuel side distribution plate is formed along the vertical direction while meandering, and the oxidant passage of the oxidant side distribution plate is formed along the vertical direction while meandering. Can be adopted. Thus, it can be applied to the serpentine type.

  According to the present invention, a mode is adopted in which a fuel side seal portion for preventing fuel from flowing to the oxidant side distribution plate side is provided in a portion other than the counterflow region in the fuel passage of the fuel side distribution plate. be able to. The fuel side seal portion can be formed of at least one of a seal plate and a resin seal.

  Further, a configuration is adopted in which an oxidant side seal portion for preventing the oxidant from flowing to the fuel side distribution plate side is provided in a portion other than the counter flow region in the oxidant passage of the oxidant side distribution plate. Can do. The oxidant side seal portion can be formed of at least one of a seal plate and a resin seal.

  Embodiment 1 of the present invention will be specifically described below with reference to FIGS. FIG. 1 schematically shows a conceptual diagram of a solid polymer fuel cell. As shown in FIG. 1, the fuel cell is formed by stacking cells in the thickness direction having a flow distribution plate 2 that sandwiches the membrane electrode assembly 1 from both sides in the thickness direction. The membrane electrode assembly 1 includes a solid polymer electrolyte membrane 10, a fuel electrode 11 provided on one side of the electrolyte membrane 10 in the thickness direction and having conductivity and gas permeability, and other electrolyte membrane 10 in the thickness direction of the electrolyte membrane 10. An oxidant electrode 12 provided on one side and having conductivity and gas permeability, a catalyst layer 13 for the fuel electrode 11 interposed between the fuel electrode 11 and the electrolyte membrane 10, an oxidant electrode 12 and the electrolyte membrane 10 And the catalyst layer 14 for the oxidant electrode 12 interposed therebetween. The catalyst layers 13 and 14 include catalyst-carrying carbon in which a catalyst is carried on a carbon support, and an electrolyte portion.

  The distribution plate 2 is made of a conductive material, for example, a carbon material or a metal material having good corrosion resistance, and is also called a separator. As shown in FIG. 2, the flow distribution plate 2 has a vertically long rectangular shape, and includes an upper side portion 20 and a lower side portion 21 that face each other, and two side portions 22 and 23 that face each other. The distribution plate 2 has protrusions 27. The protrusions 27 of the distribution plate 2 are in contact with the fuel electrode 11 and the oxidant electrode 12 to ensure electron conductivity. Electrons generated by the power generation reaction are exchanged between the distribution plate 2 and the fuel electrode 11, and the distribution plate 2. And oxidant electrode 12 can be conducted.

  As shown in FIG. 2, the oxidant gas inlet 30 (oxidant inlet) flows an oxidant gas (generally an oxygen-containing gas such as air or oxygen gas), and the upper side of the flow distribution plate 2. The side 20 is provided in a horizontally long shape. The oxidant gas outlet 31 (oxidant outlet) is provided in a horizontally long shape on the lower side 21 side of the flow distribution plate 2. The oxidant gas passage 32 has a straight oxidant gas passage 32 formed by a large number of partitioning protrusions 27 extending intermittently from the oxidant gas inlet 30 to the oxidant gas outlet 31. . Therefore, in the flow distribution plate 2, the oxidant gas flows downward (in the direction of arrow Y1) from top to bottom in the order of the oxidant gas inlet 30, the oxidant gas passage 32, and the oxidant gas outlet 31. Therefore, the oxidant gas flowing through the flow distribution plate 2 flows downward from the top to the bottom on the one surface side of the flow distribution plate 2. As shown in FIG. 2, the opening area of the oxidant gas outlet 31 is set larger than the opening area of the oxidant gas inlet 30. This is because it is considered that the produced water generated by the power generation reaction is discharged from the oxidant gas outlet 31.

  Even when the generated water is present in the oxidant gas passage 32, the oxidant gas passage 32 extends straight as described above, and the oxidant gas outlet 31 is located on the lower side of the flow distribution plate 2. Since it is provided in the part 21 side, the discharge | emission property which discharges the generated water below using gravity can be improved.

  The oxidant gas passage 32 is provided on the one surface side of the flow distribution plate 2 as described above, and the partition projection 27 causes the oxidant gas inlet 30 to face the oxidant gas outlet 31 as shown in FIG. Several are extended in parallel. The reason for the large number of protrusions 27 is to ensure electron conductivity. The widths of the oxidant gas passages 32 are basically equal.

  As shown in FIG. 2, the protrusion 27 is intermittent in the length direction via the notch portion 28, and is arranged in the vertical direction. Since the cutout portion 28 is formed, the oxidant gas passes through the cutout portion 28 so as to avoid the clogged portion of the produced water even if the produced water is clogged in the oxidant gas passage 32. As a result, the flow of the oxidant gas can be ensured.

  Next, the fuel flow will be described. As shown in FIG. 3, the fuel inlet 40 flows fuel (generally, hydrogen gas or hydrogen-containing gas) and is provided vertically below one side portion 22 of the flow distribution plate 2. . The fuel outlet 41 is provided vertically above the other side portion 22 of the flow distribution plate 2.

  The fuel passage 42 is provided on the other surface side of the flow distribution plate 2 so as to face the oxidant gas passage 32 so as to have a front-back relationship with the oxidant gas passage 32. A plurality of fuel passages 42 are extended in parallel from the fuel inlet 40 toward the fuel outlet 41. Therefore, the fuel flowing through the fuel passage 42 basically flows upward (in the direction of the arrow Y2) from the bottom to the top on the other surface side of the flow distribution plate 2. Since the oxidant gas flows upward as described above, the flow direction of the oxidant gas and the flow direction of the fuel are basically opposite to each other. In this case, it is possible to expect a dispersion action of the produced water as follows. That is, since the flow of the oxidant gas is basically downward (in the direction of arrow Y1), the generated water generated at the oxidant electrode 12 based on the power generation reaction flows downward (in the direction of arrow Y1). Therefore, the lower part of the oxidant gas passage 32 and the lower part of the oxidant electrode 12 are relatively wet, and the upper part of the oxidant gas path 32 and the upper part of the oxidant electrode 12 are relatively dry. The generated water can pass between the oxidant electrode 12 and the fuel electrode 11 through the electrolyte membrane 10. For this reason, the lower part of the oxidant electrode 12 and the lower part of the fuel electrode 11 are relatively wet, and the upper part of the oxidant electrode 12 and the upper part of the fuel electrode 11 are relatively dry. In other words, the lower part (downstream) of the oxidant gas passage 32 and the lower part (upstream) of the fuel passage 42 are relatively wet, and the upper part (upstream) of the oxidant gas passage 32 and the upper part (downstream) of the fuel passage 42. Is relatively dry.

  However, according to the present embodiment, the flow of fuel is opposite to the flow direction of the oxidant gas, and is basically upward (in the direction of arrow Y2), and therefore exists on the lower side (upstream) of the fuel passage 42. The produced water can be conveyed upward and transferred to the upper part (downstream) of the fuel passage 42. Since the generated water passes through the electrolyte membrane 10 and travels between the oxidant electrode 12 and the fuel electrode 11, the oxidant electrode 12 and the fuel electrode 11 constituting the fuel cell are between the upper part and the lower part. The moisture unevenness is reduced, and as a result, the power generation unevenness between the upper part and the lower part of the flow distribution plate 2 is reduced.

  In order to reduce power generation unevenness in this way, the length of the vertical passage (second passage 42b described later) along the vertical direction of the fuel passage 42 is set to be long so that the fuel flows upward. It is preferable that the opposing length between the longitudinal passage portion 32x of the agent gas passage 32 and the longitudinal passage (second passage 42b described later) along the vertical direction of the fuel passage 42 be as long as possible. As will be described below, the present embodiment is set to such a structure.

  As shown in FIG. 3, the fuel passage 42 will be further described. Each fuel passage 42 communicates with the first passage 42a extending from the fuel inlet 40 along the lateral direction (that is, along the lower side portion 21) and the end portion of the first passage 42a and along the longitudinal direction. A second passage 42b that extends (that is, along the side portions 22 and 23). In addition to the first passage 42a and the second passage 42b, each fuel passage 42 communicates with the upper portion of the second passage 42b and extends in the lateral direction (that is, along the upper side portion 20). 3 passages 42c. As shown in FIG. 3, the first passage 42a and the second passage 42b are L-shaped. The second passage 42b and the third passage 42c are L-shaped.

  The first passage 42 a, the second passage 42 b, and the third passage 42 c are extended by the protrusions 27. Here, in the flow distribution plate 2, the fuel flows upward (in the direction of arrow Y2) in the order of the fuel inlet 40, the first passage 42a, the second passage 42b, the third passage 42c, and the fuel outlet 41.

  According to the present embodiment, as shown in FIG. 3, one second passage 42b is formed by a branch wall 47 (a region indicated by hatching in FIG. 4) that can also function as a protrusion that ensures electron conductivity. There are multiple branches. Therefore, the number of the second passages 42b is larger than the number of the first passages 42a. That is, as shown in FIG. 4, one first passage 42 a is branched by the branch wall 47 into two second passages 42 b. In order to ensure the electron conductivity of the branch wall 47, it is preferable to increase the number in consideration of the electron conductivity with the fuel electrode 11.

  As shown in FIG. 3, the straight branch wall 47 has an upper end 47u and a lower end 47d.

  Looking at the plurality of branch walls 47, the lower end 47 d of the branch wall 47 gradually inclines along a virtual inclination line R <b> 1 that inclines so as to descend from the fuel inlet 40, as shown in FIG. 3. Further, the upper end 47u of the branch wall 47 is gradually inclined upward along a virtual inclination line R2 that is inclined so as to rise as the distance from the fuel outlet 41 increases. As shown in FIG. 3, the virtual tilt line R1 and the virtual tilt line R2 can be parallel to each other or almost parallel to each other.

  In this case, as can be understood from FIG. 3, the vertical intervals between the virtual tilt line R1 and the virtual tilt line R2 are substantially equal. Therefore, the vertical lengths of the plurality of straight branch walls 47 are basically the same. Note that the region defined by the virtual inclination line R1 and the virtual inclination line R2 is a parallelogram or a substantially parallelogram as shown in FIG.

  As shown in FIG. 3, the connecting portion between the first passage 42a and the second passage 42b and the connecting portion between the second passage 42b and the third passage 42c are bent passages 49 (49d) where the fuel passage 42 through which the fuel flows is bent. 49u). That is, portions corresponding to the virtual inclination line R1 and the virtual inclination line R2 constitute a bent passage 49 in which the fuel passage 42 through which the fuel flows is bent. As described above, the fuel passage 42 has the bent passage 49.

  FIG. 3 shows the upper bent passage as 49u and the lower bent passage as 49d. If the bent passages 49 (49d, 49u) are formed in this way, the degree of freedom in selecting the position where the fuel inlet 40 and the fuel outlet 41 are arranged in the flow distribution plate 2 can be increased. As a result, the freedom degree of the position which arrange | positions the oxidizing gas inlet 30 and the oxidizing gas outlet 31 can be raised. In particular, in this embodiment, since air is used as the oxidant, the flow rate of the oxidant gas per unit time is increased, so that it is necessary to increase the opening area of the oxidant gas inlet 30 and the oxidant gas outlet 31. However, even when the opening area is increased in this way, if the bent passage 49 is formed, the above-described degree of freedom can be obtained.

  As shown in FIG. 3, the passage width of one first passage 42a is shown as D1, the passage width of one second passage 42b is shown as D2, and the passage width of one third passage 42c is shown as D3. The relationship is D1> D2, D3> D2, and D1≈D3 (D1 = D3). However, it is not limited to this.

  As described above, according to the present embodiment in which one first passage 42a is branched into two second passages 42b, as shown in FIG. The overall width of the first passage 42a group formed (the overall width in the direction crossing the gas flow) is LA, and the overall width of the second passage group formed by the second passages 42b constituting each fuel passage 42 (gas When the overall width in the direction crossing the flow is LB, the relationship LA <LB is set. Further, when the overall width of the third passage group formed by the third passages 42c constituting each fuel passage 42 is LC, the relationship LC <LB is set. Here, LA = LC and LA≈LC.

  According to the present embodiment as described above, the second passage 42b extending in the vertical direction in the fuel passage 42 and the vertical passage portion 32x extending in the vertical direction in the oxidant gas face each other. The lengths M1 and M2 (see FIG. 3) can be increased. As a result, the area of the opposing area SA where the second passage 42b extending in the vertical direction of the fuel passage 42 and the vertical passage portion extending in the vertical direction of the oxidant gas face each other can be increased. . As a result, the area of the counterflow region where the oxidant gas and the fuel flow in opposite directions can be increased.

  For this reason, even if the generated water generated by the power generation reaction accumulates in the lower portion of the oxidant gas passage 32, the generated water permeates the electrolyte membrane 10 and permeates the fuel passage 42 side facing the oxidant gas passage 32. Furthermore, the fuel passage 42 is shifted upward (arrow Y2 direction) by the fuel flowing upward (arrow Y2 direction). Since the generated water passes through the electrolyte membrane 10 and passes between the oxidant electrode 12 and the fuel electrode 11, as a result, moisture unevenness between the upper part and the lower part of the fuel electrode 11 is reduced. As a result, moisture unevenness between the upper part and the lower part of the oxidizer electrode 12 is reduced. For this reason, the electric power generation nonuniformity resulting from the moisture nonuniformity of the upper part and the lower part in the flow distribution board 2 is reduced.

  2 and 3, the distribution plate 2 is formed with a cooling water inlet 50 through which cooling water for cooling the fuel cell is introduced, and a cooling water outlet 51 through which the cooling water flows out. Is formed. A cooling water passage communicating with the cooling water inlet 50 and the cooling water outlet 51 is formed in a distribution plate (not shown).

  According to this embodiment, the power generation region where the fuel electrode 11 and the oxidant electrode 12 face each other with the electrolyte membrane 10 interposed therebetween is a region where the projected shape of the fuel electrode 11 and the projected shape of the oxidant electrode 12 overlap. . The projected area of the oxidant electrode 12 and the projected area of the fuel electrode 11 are basically the same. Such a power generation region is provided between the virtual inclination line R1 and the virtual inclination line R2 corresponding to the bent passage 49 of the fuel passage 42 through which the fuel flows. Here, according to the present embodiment, when the projected area of the power generation region is 100%, the direction of the fuel flowing upward in the fuel passage 42 and the direction of the oxidant flowing downward in the oxidant gas passage 32 are reversed. The area of the counterflow region that is oriented is set to occupy 90% or more or 95% or more. In particular, according to the present embodiment, the power generation region where the fuel electrode 11 and the oxidant electrode 12 overlap is disposed between the upper bent passage 49u and the lower bent passage 49d, and the counterflow region (only). Is provided.

  Here, since the direction of the fuel flowing through the fuel passage and the direction of the oxidant flowing through the oxidant passage are opposite to each other in the counterflow region, the dispersed action of the generated water can be exhibited.

  As shown in FIG. 5, the projected shape of the fuel electrode 11 is inclined along the virtual inclination line R1 in the same direction from one end to the other end and the upper side portion 11u inclined along the virtual inclination line R2 from one end to the other end. A lower side 11d and side sides 11s and 11t extending in the vertical direction and facing each other. Therefore, the projected shape of the fuel electrode 11 is a parallelogram shape or a substantially parallelogram shape. The projected shape of the fuel electrode 11 means a projected shape when light is applied along the surface vertical direction of the fuel electrode 11.

  The projected shape of the oxidant electrode 12 is virtually tilted in the same direction from the upper side portion 12u along the virtual tilt line R2 tilted from one end to the other end, and from one end to the other end so as to overlap with the projected shape of the fuel electrode 11. It has a lower side portion 12d inclined along the line R1 and side portions 12s and 12t facing each other and extending along the vertical direction. Therefore, the projected shape of the oxidant electrode 12 is a parallelogram shape or a substantially parallelogram shape. The projected shape of the oxidizer electrode 12 means a projected shape when light is applied from the same direction as the projected shape of the fuel electrode 11 along the surface vertical direction of the fuel electrode 11.

  According to the present embodiment, as shown in FIG. 6, the fuel side seal plate 60 as the fuel side seal portion is provided in the fuel passage 42 of the fuel side distribution plate 2 (2A) in a portion other than the counterflow region. ing. The fuel-side seal plate 60 has a function of preventing fuel from flowing to the oxidant-side distribution plate 2 (2B) side.

  In addition, an oxidant side seal plate 62 as an oxidant side seal portion is provided in a portion other than the counter flow region in the oxidant gas passage 32 of the oxidant side distribution plate 2 (2B). The oxidant side seal plate 62 has a function of preventing the oxidant gas from flowing to the fuel side distribution plate 2 (2A). The fuel side seal plate 60 and the oxidant side seal plate 62 are integrally coupled by a resin binder layer 64.

  As shown in FIG. 7, a fuel side seal plate 70 as a fuel side seal portion is provided at the fuel inlet 40 communicating with the fuel passage 42 of the fuel side distribution plate 2 (2A). The fuel-side seal plate 70 has a function of preventing fuel from flowing to the oxidant-side distribution plate side 2 (2B). Further, an oxidant side seal plate 72 as an oxidant side seal portion is provided at the oxidant gas outlet 31 communicating with the oxidant gas passage 32 of the oxidant side flow distribution plate 2 (2B). The oxidant side seal plate 72 has a function of preventing the oxidant gas from flowing into the fuel side distribution plate 2 (2A). The fuel side seal plate 70 and the oxidant side seal plate 72 are integrally coupled by a resin binder layer 74.

  FIG. 5 shows a projected shape of the fuel side seal plate 60. As shown in FIG. 5, the projected shape of the fuel-side seal plate 60 has a substantially triangular shape including a lower side portion 60d that is inclined from one end to the other end along the virtual inclination line R2. Similarly, the projected shape of the oxidant-side seal plate 62 is substantially triangular with an upper side 62d that is inclined from one end to the other end along the virtual inclined line R2.

  FIG. 5 shows a projected shape of the fuel side seal plate 70. As shown in FIG. 5, the projected shape of the fuel-side seal plate 70 has a substantially triangular shape including an upper side portion 70d that is inclined from one end to the other end along the virtual inclination line R1. Similarly, the projected shape of the oxidant side seal plate 72 has a substantially triangular shape including an upper side portion 72d that is inclined from one end to the other end along the virtual inclined line R1.

  The bent passages 49 (49u, 49d) are resistant to water discharge, so that water is likely to accumulate, which tends to cause a non-uniform water distribution and hence a non-uniform current density distribution. In this regard, according to this embodiment, the power generation region of the fuel cell is a region where the fuel electrode 11 and the oxidant electrode 12 overlap. Here, when the projected area of the power generation region is 100%, the counterflow is such that the direction of the fuel flowing upward in the fuel passage 42 is opposite to the direction of the oxidant gas flowing downward in the oxidant gas passage 32. The area of the region is set to occupy 90% or more or 95% or more of the power generation region. In particular, according to the present embodiment, the power generation region where the projected shape of the fuel electrode 11 and the projected shape of the oxidant electrode 12 overlap is formed between the virtual inclined line R1 and the virtual inclined line R2, and the counter flow It is provided in the area (only). Here, the counterflow region has an action of dispersing generated water.

  According to this embodiment, when the water accumulated in the downstream of the oxidant gas passage 32 penetrates the electrolyte membrane 10 and moves to the fuel passage 42 side, the fuel gas flowing through the fuel passage 42 converts the water into the fuel passage 42. , That is, upstream of the oxidant gas passage 32. As a result, the occurrence of non-uniformity in the water distribution in the power generation region can be suppressed, the uniformity of the current density distribution when the power generation region generates power can be increased, and the power generation efficiency can be increased. .

  8 and 9 show a second embodiment. The present embodiment basically has the same configuration and function as the first embodiment. FIG. 8A shows the oxidant side distribution plate 2B. As shown in FIG. 8A, the oxidant gas passage 32, which is the cathode flow path of the oxidant side distribution plate 2B, is a serpentine type and is formed to meander through the bent passages 39a and 39b.

  The oxidant gas inlet 30 flows oxidant gas (generally oxygen-containing gas such as air or oxygen gas) and is provided on the upper side of the flow distribution plate 2 (2B). The oxidant gas outlet 31 is provided on the lower side of the flow distribution plate 2 (2B). The oxidant gas passage 32 is formed by a number of partitioning projections 27 extending from the oxidant gas inlet 30 to the oxidant gas outlet 31. Accordingly, in the flow distribution plate 2 (2B), the oxidant gas flows downward while meandering from top to bottom in the order of the oxidant gas inlet 30, the oxidant gas passage 32, and the oxidant gas outlet 31. Therefore, the oxidant gas flowing through the flow distribution plate 2 (2B) basically flows downward (in the direction of arrow Y4) from the top to the bottom on the other surface side of the flow distribution plate 2 (2B). This is to increase the discharge of generated water using gravity.

  Even when generated water is present in the oxidant gas passage 32, the oxidant gas outlet 31 is provided on the lower side of the flow distribution plate 2 as described above. It is possible to improve the discharge property that discharges.

  FIG. 9A shows the fuel-side distribution plate 2A. As shown in FIG. 9A, the fuel passage 42, which is the anode passage of the fuel side distribution plate 2A, is a serpentine type, and is formed meandering through bent passages 49a, 49b, 49c, 49d. The fuel passage 42 is provided on one surface side of the flow distribution plate 2 so as to face the oxidant gas passage 32 so as to have a front-back relationship with the oxidant gas passage 32. The fuel flowing through the fuel passage 42 basically flows upward (in the direction of the arrow Y5) while meandering from below to above in the distribution plate 2 (2A). Since the oxidant gas flows downward as described above, the flow direction of the oxidant gas and the flow direction of the fuel are basically opposite to each other. In this case, as described above, it is possible to expect the effect of dispersing the generated water.

  That is, since the flow of the oxidant gas is downward, the generated water generated at the oxidant electrode 12 based on the power generation reaction flows downward using gravity. Therefore, the lower part of the oxidant gas passage 32 and the lower part of the oxidant electrode 12 are relatively wet, and the upper part of the oxidant gas path 32 and the upper part of the oxidant electrode 12 are relatively dry. The generated water can pass between the oxidant electrode 12 and the fuel electrode 11 through the electrolyte membrane 10. For this reason, the lower part of the oxidant electrode 12 and the lower part of the fuel electrode 11 are relatively wet, and the upper part of the oxidant electrode 12 and the upper part of the fuel electrode 11 are relatively dry. In other words, the lower part (downstream) of the oxidant gas passage 32 and the lower part (upstream) of the fuel passage 42 are relatively wet, and the upper part (upstream) of the oxidant gas passage 32 and the upper part (downstream) of the fuel passage 42. Is relatively dry.

  However, according to the present embodiment, since the fuel flow is basically upward, the generated water existing on the lower side of the fuel passage 42 can be transported upward and transferred to the upper portion (downstream) of the fuel passage 42. it can. And since generated water permeates the electrolyte membrane 10 and travels between the oxidant electrode 12 and the fuel electrode 11, the water becomes uneven between the upper part and the lower part of the oxidant electrode 12 and the fuel electrode 11, Moisture unevenness is reduced. As a result, the nonuniformity of the current density distribution between the upper part and the lower part of the flow distribution plate 2 is reduced. Thus, in order to reduce the non-uniformity of the current density distribution, when the projected area of the power generation region is 100%, the flow direction of the fuel flowing in the fuel passage 42 and the oxidant flowing in the oxidant gas passage 32 are set. It is preferable to increase the ratio of the counterflow region in which the direction of is opposite.

  According to the present embodiment, when the projected area of the power generation region is 100%, the direction in which the fuel flows upward in the fuel passage 42 is opposite to the direction in which the oxidant gas flows downward in the oxidant gas passage 32. The area of the counterflow region is set to occupy 90% or more or 95% or more of the power generation region (substantially 100%). Therefore, it can be said that the power generation region is provided (only) in the counterflow region.

  That is, as shown in FIG. 8B, the projected shape of the oxidant electrode 12 is set so as to overlap the counterflow region. As shown in FIG. 9B, the projected shape of the fuel electrode 11 is set so as to overlap the counterflow region.

  As shown in FIGS. 8B and 9B, the oxidant electrode 12 and the fuel electrode 11 have basically the same projected area. The projected shape of the oxidant electrode 12 means a projected shape when light is applied along the surface vertical direction of the oxidant electrode 12. The projected shape of the fuel electrode 11 means a projected shape when light is applied along the surface vertical direction of the fuel electrode 11. As described above, according to the present embodiment, the power generation region is set to overlap with the counterflow region, and is provided (only) in the counterflow region.

  According to the present embodiment, as shown in FIG. 10, a fuel side seal plate 60 as a fuel side seal portion is provided in a portion of the fuel passage 42 of the fuel side distribution plate 2 (2A) other than the counterflow region. ing. The fuel-side seal plate 60 has a function of preventing fuel from flowing to the oxidant-side distribution plate 2 (2B) side. Further, as shown in FIG. 10, an oxidant side seal plate 62 as an oxidant side seal portion is provided in a portion other than the counterflow region in the oxidant gas passage 32 of the oxidant side flow distribution plate 2 (2B). Yes. The oxidant side seal plate 62 has a function of preventing the oxidant from flowing into the fuel side distribution plate 2 (2A). The fuel side seal plate 60 and the oxidant side seal plate 62 are joined by a resin binder layer 64.

Similarly, although not particularly illustrated, a fuel side seal plate is provided in a portion other than the counterflow region in the fuel passage 42 of the fuel side distribution plate 2 (2A). Further, an oxidant side seal plate is provided in a portion other than the counter flow in the oxidant gas passage 32 of the oxidant side distribution plate 2 (2B).
(Other examples)
In addition, the present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications without departing from the scope of the invention. In the embodiment, the flow distribution plate in which the oxidant flow path is formed on one side and the fuel flow path is formed on the other side is described. However, the flow distribution plate is not limited to this, and the fuel flow is formed on one side. You may apply to the flow distribution board in which the path was formed.

  The present invention can be used in, for example, fuel cell power generation systems for vehicles, stationary devices, portable devices, electric devices, electronic devices, and the like.

It is a conceptual diagram which shows typically the internal structure of a fuel cell. It is a front view which shows typically the oxidant gas channel | path side of a flow distribution plate. It is a front view which shows typically the fuel channel side of a distribution board. FIG. 3 is a partial front view schematically showing an enlarged fuel passage side of a flow distribution plate. It is a front view which shows typically the electric power generation area | region where a fuel electrode and an oxidizing agent electrode superpose | polymerize. It is sectional drawing which shows typically a fuel exit vicinity. It is sectional drawing which shows typically a fuel inlet_port | entrance vicinity. (A) is a front view schematically showing the oxidant gas passage side of the flow distribution plate, and (B) is a front view schematically showing the flow distribution plate and the oxidant electrode. (A) is a front view schematically showing the fuel passage side of the flow distribution plate, and (B) is a front view schematically showing the flow distribution plate and the fuel electrode. It is sectional drawing which shows typically a seal plate vicinity.

Explanation of symbols

  In the figure, 11 is a fuel electrode, 12 is an oxidant electrode, 2 is a flow distribution plate, 20 is an upper side, 21 is a lower side, 22 is a side, 30 is an oxidant gas inlet, 31 is an oxidant gas outlet, 32 Is an oxidant gas passage, 40 is a fuel inlet, 41 is a fuel outlet, 42 is a fuel passage, 42a is a first passage, 42b is a second passage, 42c is a third passage, and 60 and 70 are fuel side seal plates (fuel side Seal parts), 62 and 72 are oxidant side seal plates (oxidant side seal parts), and 64 and 74 are resin binder layers.

Claims (11)

A membrane electrode assembly having an electrolyte membrane having ion conductivity and a fuel electrode and an oxidizer electrode sandwiching the electrolyte membrane;
A fuel side distribution plate having a fuel passage for supplying fuel to the fuel electrode;
In a fuel cell comprising an oxidant side flow plate having an oxidant passage for supplying an oxidant to the oxidant electrode,
At least one of the fuel passage of the fuel side distribution plate and the oxidant passage of the oxidant side distribution plate has a bent passage; and
When the projected area projected onto the electrolyte membrane in the power generation region facing the fuel electrode and the oxidizer electrode across the electrolyte membrane is 100%, the flow direction of the fuel flowing through the fuel passage and the oxidizer passage A fuel cell, characterized in that the projected area of the counterflow region in which the direction of the oxidant flowing in the opposite direction is opposite to 70% or more.   2. The basic flow direction of the oxidant flowing through the oxidant passage is a direction flowing from top to bottom, and the basic flow direction of the fuel flowing through the fuel passage is a direction flowing from bottom to top. The fuel cell characterized by the above-mentioned.   In Claim 1 or 2, at least one of the fuel passage of the fuel side distribution plate and the oxidant passage of the oxidant side distribution plate has at least two bent passages, and the power generation region is A fuel cell disposed between the bent passages.   The fuel cell according to claim 1, wherein the power generation region is provided only in the counterflow region. 5. The projected shape of the fuel electrode according to claim 1, wherein the projected shape of the fuel electrode is an upper side portion that is inclined from one end to the other end, a lower side portion that is inclined in the same direction from one end to the other end, and a vertical direction. And opposing sides extending along the sides,
The projected shape of the oxidant electrode has an upper side portion that is inclined from one end to the other end, a lower side portion that is inclined in the same direction from the one end to the other end, and a vertical direction so as to overlap with the projected shape of the fuel electrode. A fuel cell comprising extended side portions facing each other. 6. The fuel passage according to claim 1, wherein each of the fuel passages extends in the lateral direction from the fuel inlet, communicates with the first passage, and extends in the longitudinal direction. And a second passage extending
LA <LB, where LA is the overall width of the first passages constituting each fuel passage, and LB is the overall width of the second passages constituting each fuel passage. Fuel cell. In any one of Claims 1-6, While the said fuel channel of the said fuel side distribution board is formed along the up-down direction, meandering via a bending channel | path,
The fuel cell according to claim 1, wherein the oxidant passage of the oxidant side distribution plate is formed along a vertical direction while meandering through a bent passage.   The fuel according to any one of claims 1 to 7, wherein fuel is prevented from flowing to the oxidant side distribution plate side in a portion other than the counterflow region in the fuel passage of the fuel side distribution plate. A fuel cell comprising a side seal portion.   9. The oxidant is prevented from flowing to the fuel-side distribution plate side in a portion other than the counterflow region in the oxidant passage of the oxidant-side distribution plate according to claim 1. A fuel cell characterized in that an oxidant-side seal portion is provided. In a fuel cell distribution plate having a bent passage and supplying fuel or oxidant to a fuel electrode or oxidant electrode constituting a membrane electrode assembly,
When the projected area projected onto the electrolyte membrane in the power generation region facing the fuel electrode and the oxidizer electrode across the electrolyte membrane is 100%, the direction of fuel flow and the direction of oxidant flow are opposite. A fuel cell flow distribution plate, wherein the projected area of the counterflow region occupies 70% or more.   11. The fuel cell flow distributor plate according to claim 10, wherein the fuel cell distribution plate has at least two bent passages, and the power generation region is disposed between the bent passages.

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