JP5354943B2 - Fuel cell system - Google Patents

Description

  The present invention provides a fuel cell stack in which a plurality of power generation cells are stacked, and an ejector that introduces a reaction gas into the fuel cell stack and returns spent reaction gas discharged from the fuel cell stack to the fuel cell stack. And a reaction gas supply mechanism connected to one end plate of the fuel cell stack.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (an electrolyte / electrode structure) in which an anode electrode and a cathode electrode are disposed on both sides of an electrolyte membrane (electrolyte) made of a polymer ion exchange membrane, respectively. ) Is held by a separator. This type of fuel cell is normally used as a fuel cell stack by stacking a predetermined number of power generation cells.

  By the way, in the fuel cell, fuel gas such as hydrogen gas is supplied to the anode side electrode, and fuel off-gas containing unreacted fuel gas that is not used for power generation is discharged from the fuel cell. Therefore, in consideration of economy, in order to effectively use the fuel gas, the fuel off-gas is supplied again to the anode side electrode as the fuel gas.

  For example, as shown in FIG. 5, a fuel cell system disclosed in Patent Document 1 is a hydrogen supply path for supplying hydrogen from a hydrogen supply device 1 to a fuel cell 2 (a stack of a plurality of power generation cells 2a). 3, the off gas discharged from the fuel cell 2 joins the hydrogen supply path 3 and is recirculated to the fuel cell 2, the off gas is circulated to the off gas circulation path 4, and the off gas The amount of circulation is controllable, and an ejector pump 5 that mixes off-gas with main supply hydrogen and a pressure sensor 6 that detects the discharge pressure of the ejector pump 5 are provided.

JP 2004-95528 A

  By the way, when the ejector pump 5 is disposed in the vicinity of the fuel cell 2, hydrogen is discharged from the ejector pump 5 into the hydrogen supply communication hole of the fuel cell 2 at a high pressure. For this reason, a static pressure distribution is likely to occur in the hydrogen supply communication hole. As a result, in the fuel cell 2, hydrogen is not sufficiently supplied to the power generation cell 2a located particularly on the hydrogen inlet side, and there is a problem that power generation performance is deteriorated.

  The present invention has been made in response to this type of request, and provides a fuel cell system that can uniformly and reliably distribute and supply reaction gas to each power generation cell stacked in the fuel cell stack. The purpose is to provide.

A fuel cell system according to the present invention includes a fuel cell stack in which a plurality of power generation cells are stacked and a reaction gas supply communication hole that supplies at least a reaction gas that is a fuel gas or an oxidant gas is provided along the stacking direction. An ejector that discharges the reaction gas to the reaction gas supply communication hole in the stacking direction of the power generation cells and returns the used reaction gas discharged from the fuel cell stack to the reaction gas supply communication hole ; provided on the outer side of one of the end plates of the fuel cell stack, and a reaction gas supply mechanism connected to the end plate before Symbol hand.

In this fuel cell system, the center line of the reaction gas discharge port of the ejector is located outside the opening shape line forming the reaction gas supply communication hole, and the reaction gas supply communication hole and the reaction gas discharge port communicate with each other. However, a manifold member provided integrally with one end plate is provided. The manifold member has a manifold passage portion having an opening shape substantially the same as the opening shape of the reaction gas supply communication hole, an opening shape different from the manifold passage portion, and the reaction gas discharged from the reaction gas discharge port is And a reaction gas introduction portion that leads to the manifold passage portion .

  Furthermore, it is preferable that the reaction gas is a fuel gas and the reaction gas supply communication hole is a fuel gas supply communication hole.

  According to the present invention, the reaction gas discharged from the reaction gas discharge port of the ejector is introduced into the reaction gas supply communication hole after at least a part thereof is sprayed on the passage wall surface or the like. For this reason, the flow rate of the reaction gas is reduced, and the static pressure distribution in the reaction gas supply communication hole is improved. Thereby, it becomes possible to distribute and supply the reaction gas uniformly and reliably to each power generation cell stacked in the fuel cell stack, and the power generation performance and startability are effectively improved.

  FIG. 1 is a schematic configuration diagram of a fuel cell system 10 according to an embodiment of the present invention.

  The fuel cell system 10 is mounted on a fuel cell vehicle (not shown). The fuel cell stack 14, a cooling medium supply mechanism 16 for supplying a cooling medium to the fuel cell stack 14, and the fuel cell stack 14 are oxidized. An oxidant gas supply mechanism 18 for supplying an agent gas (reactive gas) and a fuel gas supply mechanism 20 for supplying a fuel gas (reactive gas) to the fuel cell stack 14 are provided.

  The cooling medium supply mechanism 16 includes a radiator 24. A cooling medium supply pipe 28 and a cooling medium discharge pipe 30 are connected to the radiator 24 via a refrigerant pump 26.

  The oxidant gas supply mechanism 18 includes an air pump 32 disposed close to the refrigerant pump 26. An air supply pipe 34 having one end connected to the air pump 32 is connected to the humidifier 36, and the fuel cell stack 14 is connected to the humidifier 36 via a humidified air supply pipe 38. Is done. The fuel cell stack 14 and the humidifier 36 are connected to an off gas supply pipe 40 for supplying an oxidant gas containing used reaction product water (hereinafter referred to as off gas) as a humidified fluid. In the humidifier 36, a back pressure valve 42 is disposed on the discharge side of the off gas supplied through the off gas supply pipe 40.

  The fuel gas supply mechanism 20 includes a fuel gas tank 44 in which hydrogen gas is stored as fuel gas. One end of a fuel gas pipe 45 is connected to the fuel gas tank 44, and the fuel gas pipe 45 is connected to the fuel cell stack 14 via a shut-off valve 46, a regulator 48 and an ejector 50.

  An exhaust fuel gas pipe 52 through which used fuel gas is discharged is connected to the fuel cell stack 14. The exhaust fuel gas pipe 52 is connected to the ejector 50 via a return pipe 54 and partly communicates with the purge valve 56.

  In the fuel cell stack 14, a plurality of power generation cells 60 are stacked in the horizontal direction (the direction of arrow A in FIG. 2), and at both ends in the stacking direction, although not shown, a metal plate is interposed via a terminal plate and an insulating plate. End plates 62a and 62b are disposed (see FIG. 1). The fuel cell stack 14 includes, for example, a casing (not shown) having end plates 62a and 62b as end plates, or tie rods (not shown) that fasten the end plates 62a and 62b.

  The terminal plate is provided with power extraction terminals 63a and 63b. The power extraction terminals 63a and 63b protrude outward from the end plates 62a and 62b in the stacking direction, and are connected to a traveling motor and auxiliary equipment (not shown). .

  As shown in FIG. 2, each power generation cell 60 includes an electrolyte membrane / electrode structure 66 and first and second separators 68 and 70 that sandwich the electrolyte membrane / electrode structure 66, and has a vertically long configuration. Is done. In addition, the 1st and 2nd separators 68 and 70 are comprised with a carbon separator or a metal separator.

  One end edge (upper end edge) of the power generation cell 60 in the long side direction (arrow C direction) communicates with each other in the arrow A direction to supply an oxidant gas, for example, an oxygen-containing gas. A supply communication hole 72a and a fuel gas supply communication hole (reaction gas supply communication hole) 76a for supplying a fuel gas, for example, a hydrogen-containing gas, are provided.

  The other end edge (lower end edge) in the long side direction of the power generation cell 60 communicates with each other in the direction of the arrow A, and discharges the oxidant gas discharge communication hole 72b for discharging the oxidant gas and the fuel gas. A fuel gas discharge communication hole 76b is provided.

  A cooling medium supply communication hole 74a for supplying a cooling medium is provided at one end edge of the power generation cell 60 in the short side direction (arrow B direction), and the other end edge of the power generation cell 60 in the short side direction. Is provided with a cooling medium discharge communication hole 74b for discharging the cooling medium. The cooling medium supply communication hole 74a and the cooling medium discharge communication hole 74b are set in a vertically long shape.

  The electrolyte membrane / electrode structure 66 includes, for example, a solid polymer electrolyte membrane 78 in which a thin film of perfluorosulfonic acid is impregnated with water, and an anode side electrode 80 and a cathode side electrode 82 that sandwich the solid polymer electrolyte membrane 78. With.

  A fuel gas flow path 84 that connects the fuel gas supply communication hole 76 a and the fuel gas discharge communication hole 76 b is formed on the surface 68 a of the first separator 68 facing the electrolyte membrane / electrode structure 66. The fuel gas channel 84 is constituted by, for example, a groove extending in the direction of arrow C. A cooling medium flow path 86 that connects the cooling medium supply communication hole 74 a and the cooling medium discharge communication hole 74 b is formed on the surface 68 b opposite to the surface 68 a of the first separator 68. The cooling medium flow path 86 is constituted by a groove portion extending in the arrow B direction.

  The surface 70a of the second separator 70 facing the electrolyte membrane / electrode structure 66 is provided with, for example, an oxidant gas flow path 88 formed of a groove extending in the direction of arrow C. The oxidant gas supply communication hole 72a and the oxidant gas discharge communication hole 72b communicate with each other. A cooling medium flow path 86 is integrally formed on the surface 70b opposite to the surface 70a of the second separator 70 so as to overlap the surface 68b of the first separator 68. Although not shown, the first and second separators 68 and 70 are provided with seal members as necessary.

  As shown in FIG. 3, a resin manifold member 90 is attached to the end plate 62b. The manifold member 90 communicates with the fuel gas supply communication hole 76a and protrudes outward from the end plate 62b, and a manifold passage portion 92a provided with a horizontally long passage 91a corresponding to the opening shape of the fuel gas supply communication hole 76a. A fuel gas introduction part (reaction gas introduction part) 92b provided with a circular passage 91b and a connecting cylinder part 92c for connecting the manifold passage part 92a and the fuel gas introduction part 92b are integrally provided.

  As shown in FIGS. 3 and 4, the opening shape line forming the fuel gas supply communication hole 76 a and the opening shape line forming the passage 91 a are the same and have a common base 93. The center line O of the passage 91b of the fuel gas introduction portion 92b is set to be outside the opening shape line, in this embodiment, in a range away from the same position as the common base 93 outward (downward in this embodiment). Is done.

  The ejector 50 includes a main body portion 94 and a cylindrical portion 96, and the main body portion 94 accommodates a nozzle 98 and a diffuser 100. An off gas passage 104 is formed in the main body portion 94. The nozzle 98 is provided with a fuel gas passage 106 communicating with the fuel gas pipe 45, and this fuel gas passage 106 is opened into the diffuser 100 from an injection port 110 provided at the tip of the nozzle 98.

  A return pipe 54 communicates with the off gas passage 104 and communicates with the suction chamber 114 through a hole 112 formed on the outer periphery of the diffuser 100. The suction chamber 114 communicates with a discharge passage (reactive gas discharge port) 116 that is reduced in diameter toward the distal end side and then continuously increases in diameter toward the downstream in the flow direction.

  The center line O of the discharge passage 116 coincides with the center line O of the fuel gas introduction portion 92b, and the center line O of the discharge passage 116 is outside the opening shape line of the fuel gas supply communication hole 76a, this embodiment. Then, it arrange | positions in the range spaced apart from the same position as the common base 93 outward.

  An intermediate joint 120 is disposed at a connection portion that connects the tip of the cylindrical portion 96 and the fuel gas introduction portion 92 b of the manifold member 90. The intermediate joint 120 is a cylindrical member, and integrally includes a small diameter portion 122 and a large diameter portion 124.

  Circumferential grooves 126a and 126b are formed in the small diameter portion 122 and the large diameter portion 124, respectively. The small-diameter portion 122 is provided with an O-ring 128a in the circumferential groove 126a to be fitted into the cylindrical portion 96 of the ejector 50, while the large-diameter portion 124 is provided with an O-ring 128b in the circumferential groove 126b. It fits into 90 fuel gas introduction parts 92b.

  The operation of the fuel cell system 10 configured as described above will be described below.

  First, as shown in FIG. 1, the air pump 32 constituting the oxidant gas supply mechanism 18 is driven, and external air that is an oxidant gas is sucked and introduced into the air supply pipe 34. This air is introduced into the humidifier 36 from the air supply pipe 34 and supplied to the humidified air supply pipe 38.

  At that time, as will be described later, off-gas which is an oxidant gas used for the reaction is supplied to the off-gas supply pipe 40. For this reason, moisture contained in the off-gas moves to the air before use, and the air before use is humidified. The humidified air is supplied from the humidified air supply pipe 38 to the oxidant gas supply communication hole 72a in the fuel cell stack 14 through the end plate 62b.

  On the other hand, in the fuel gas supply mechanism 20, after the shutoff valve 46 is opened, the fuel gas (hydrogen gas) in the fuel gas tank 44 is stepped down by the regulator 48, and then the fuel cell stack passes from the ejector 50 through the end plate 62b. 14 is introduced into the fuel gas supply communication hole 76a.

  Further, in the cooling medium supply mechanism 16, under the action of the refrigerant pump 26, the cooling medium is introduced from the cooling medium supply pipe 28 through the end plate 62 a to the cooling medium supply communication hole 74 a in the fuel cell stack 14.

  As shown in FIG. 2, the air supplied to each power generation cell 60 in the fuel cell stack 14 is introduced into the oxidant gas flow path 88 of the second separator 70 from the oxidant gas supply communication hole 72a, and the electrolyte membrane / It moves along the cathode side electrode 82 of the electrode structure 66. On the other hand, the fuel gas is introduced into the fuel gas flow path 84 of the first separator 68 from the fuel gas supply communication hole 76 a and moves along the anode side electrode 80 of the electrolyte membrane / electrode structure 66.

  Therefore, in each electrolyte membrane / electrode structure 66, the oxygen in the air supplied to the cathode side electrode 82 and the fuel gas (hydrogen) supplied to the anode side electrode 80 undergo an electrochemical reaction in the electrode catalyst layer. To generate electricity.

  Next, the air consumed by being supplied to the cathode side electrode 82 flows along the oxidant gas discharge communication hole 72b, and is then discharged from the end plate 62b to the off gas supply pipe 40 as an off gas (see FIG. 1). This off gas is supplied to the humidifier 36 as a humidifying gas.

  Similarly, the fuel gas consumed by being supplied to the anode side electrode 80 is discharged and flows into the fuel gas discharge communication hole 76b, and is discharged from the end plate 62b to the discharged fuel gas pipe 52 as the discharged fuel gas (see FIG. 1). A part of the discharged fuel gas discharged to the discharged fuel gas pipe 52 passes through the return pipe 54 and is mixed into new fuel gas under the suction action of the ejector 50 and is supplied into the fuel cell stack 14. The remaining discharged fuel gas is discharged under the action of opening the purge valve 56.

  As shown in FIG. 2, the cooling medium is introduced into the cooling medium flow path 86 between the first and second separators 68 and 70 from the cooling medium supply communication hole 74 a and then flows along the arrow B direction. . The cooling medium cools the electrolyte membrane / electrode structure 66, moves through the cooling medium discharge communication hole 74 b, and is discharged from the end plate 62 a to the cooling medium discharge pipe 30. As shown in FIG. 1, the cooling medium is cooled by a radiator 24 and then supplied to the fuel cell stack 14 from a cooling medium supply pipe 28 under the action of a refrigerant pump 26.

  In this case, in this embodiment, as shown in FIG. 3, the fuel gas supplied from the fuel gas pipe 45 to the fuel gas passage 106 of the nozzle 98 is diffused from the injection port 110 provided at the tip of the nozzle 98. Is injected into. For this reason, a negative pressure is generated in the suction chamber 114, and the exhaust fuel gas is sucked into the suction chamber 114 from the return pipe 54 through the off gas passage 104.

  Accordingly, the discharged fuel gas is mixed with the fuel gas injected from the nozzle 98, and the mixed fuel gas is discharged from the discharge passage 116 of the diffuser 100 toward the fuel gas supply communication hole 76a.

  At this time, as shown in FIGS. 3 and 4, the center line O of the discharge passage 116 is outside the opening shape line of the fuel gas supply communication hole 76a, more specifically, from the same position as the common base 93. It is arrange | positioned in the range spaced apart. For this reason, part of the fuel gas discharged from the discharge passage 116 is blown toward the inner peripheral surface of the connecting cylinder portion 92c, and then supplied to the fuel gas supply communication hole 76a through the passage 91a.

  As a result, the flow rate of the fuel gas discharged from the discharge passage 116 at a relatively high speed decreases, and the static pressure distribution in the fuel gas supply communication hole 76a is improved. Accordingly, the fuel gas can be uniformly and reliably distributed and supplied to the plurality of power generation cells 60 constituting the fuel cell stack 14, and the power generation performance and startability can be effectively improved. It is done.

  In the present embodiment, the fuel gas circulated and supplied to the fuel cell stack 14 as the reaction gas has been described. However, the present invention is not limited to this, and the oxidizing gas is used as the reaction gas. The present invention can also be applied to the case of circulating supply to the stack 14. It is particularly suitable when pure oxygen is used as the oxidant gas.

1 is a schematic configuration diagram of a fuel cell system according to an embodiment of the present invention. It is a disassembled perspective explanatory drawing of the electric power generation cell which comprises the said fuel cell stack. It is principal part sectional drawing of the said fuel cell system. It is principal part explanatory drawing of the said fuel cell system. 2 is an explanatory diagram of a fuel cell system disclosed in Patent Document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell system 14 ... Fuel cell stack 16 ... Cooling medium supply mechanism 18 ... Oxidant gas supply mechanism 20 ... Fuel gas supply mechanism 44 ... Fuel gas tank 45 ... Fuel gas pipe 50 ... Ejector 52 ... Exhaust fuel gas pipe 54 ... Return pipe 60 ... Power generation cell 62a, 62b ... End plate 66 ... Electrolyte membrane / electrode structure 68, 70 ... Separator 72a ... Oxidant gas supply communication hole 72b ... Oxidant gas discharge communication hole 74a ... Cooling medium supply communication hole 74b ... Cooling medium Discharge communication hole 76a ... Fuel gas supply communication hole 76b ... Fuel gas discharge communication hole 78 ... Solid polymer electrolyte membrane 80 ... Anode side electrode 82 ... Cathode side electrode 84 ... Fuel gas flow path 86 ... Cooling medium flow path 88 ... Oxidant Gas passage 90 ... Manifold member 91a, 91b ... Passage 92a ... Manifold passage 92b ... Fuel Gas introduction part 92c ... Connecting cylinder part 93 ... Base 94 ... Main body part 96 ... Cylindrical part 98 ... Nozzle 100 ... Diffuser 104 ... Off-gas passage 106 ... Fuel gas passage 110 ... Injection port 114 ... Suction chamber 116 ... Discharge passage 120 ... Middle Joint

Claims (2)

A fuel cell stack in which a plurality of power generation cells are stacked and provided with a reaction gas supply communication hole for supplying at least a reaction gas that is a fuel gas or an oxidant gas along the stacking direction;
With discharging the reaction gas toward the stacking direction of the power generation cell in the reactant gas supply passage, the ejector return the spent reaction gas discharged from the fuel cell stack to the reaction gas supply passage is, the fuel provided on the outer side of one of the end plates of the cell stack, and the reaction gas supply mechanism connected to the end plate before Symbol hand,
With
A center line of the reaction gas discharge port of the ejector is located outside an opening shape line forming the reaction gas supply communication hole ,
A manifold member that is provided integrally with the one end plate through the reaction gas supply communication hole and the reaction gas discharge port;
The manifold member has a manifold passage portion having an opening shape substantially the same as the opening shape of the reaction gas supply communication hole;
A reaction gas introduction portion having an opening shape different from that of the manifold passage portion, and leading the reaction gas discharged from the reaction gas discharge port to the manifold passage portion;
Fuel cell system comprising: a. In claim 1 Symbol placement of the fuel cell system, wherein the reaction gas, with a fuel gas,
The reaction gas supply communication hole is a fuel gas supply communication hole.

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