JP2012226846A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve highly accurate and secure measurement of a surface pressure distribution in a fuel cell stack by ensuring satisfactory adhesion with a compact and economical configuration.SOLUTION: A capacitance type surface pressure measurement device 14 constituting a fuel cell system 10 include: a plurality of dielectric bodies 50 respectively positioned in power generation surfaces of power generation cells; and a lattice-shaped conductive part 52 which extends along the direction of the power generation surfaces of the power generation cells, and allows current to flow between the dielectric bodies 50 toward a stacking direction. The lattice-shaped conductive part 52 includes a plurality of first planar parts 64 and a plurality of second planar parts 66 which are integrated with each other via individual lattice intersection parts 68. A thin wall part 70 is disposed on at least one of the lattice intersection parts 68.

Description

  The present invention includes a fuel cell stack having an electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of an electrolyte, and a power generation cell having the electrolyte / electrode structure and a separator, and the fuel cell. The present invention relates to a fuel cell system including a capacitance-type surface pressure measuring device disposed in a stack and measuring a surface pressure of the power generation cell.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (MEA) in which an anode side electrode and a cathode side electrode are disposed on both sides of an electrolyte membrane (electrolyte) made of a polymer ion exchange membrane is used as a separator. A power generation cell sandwiched between the two. In this type of fuel cell, a predetermined number of power generation cells are usually stacked, and a terminal plate, an insulating plate, and an end plate are disposed at both ends in the stacking direction to constitute a fuel cell stack. The fuel cell stack is mounted on a fuel cell vehicle such as a fuel cell electric vehicle.

  In this fuel cell stack, a clamping load is applied between the pair of end plates in the stacking direction of the power generation cells by a clamping bolt, a casing, or the like. At that time, if the surface pressure of the electrode surface of the power generation cell varies (surface pressure distribution), the contact resistance may increase and the terminal voltage may decrease.

  Therefore, it is necessary to measure the surface pressure distribution in the fuel cell stack. For example, a surface pressure distribution detection device for a stacked battery disclosed in Patent Document 1 is known. As shown in FIG. 9, the surface pressure distribution detection device includes an inner insulating portion 2 that can be elastically deformed in the stacking direction of the unit cells 1, and a plurality of first electrodes 3 a provided on one side surface of the inner insulating portion 2. A plurality of second electrodes 3b provided on the other side surface of the inner insulating portion 2 and opposed to the first electrode 3a; between the first electrode 3a and the first electrode unit cell 1; and the second electrode A pair of outer insulating portions 4 provided between 3b and the second electrode side unit cell 1, and configured to be elastically deformable in the stacking direction, and electrically insulated from the first electrode 3a and the second electrode 3b. In the state, a plurality of conductive portions 5 that electrically connect the first electrode side unit cell 1 and the second electrode side unit cell 1 are provided.

  Then, the surface pressure distribution measuring unit calculates the lamination surface pressure based on the capacitance that changes according to the facing distance between the first electrode 3a and the second electrode 3b, and obtains the lamination surface pressure distribution. Thereby, the deviation of the current density of the current passing through the first electrode side unit cell 1 and the second electrode side unit cell 1 can be suppressed, and the deterioration of the power generation performance due to the current density can be suppressed, while the unit The surface pressure distribution in the cell 1 can be detected.

JP 2010-276520 A

  However, the above-described Patent Document 1 has a surface pressure detection structure that functions as a diaphragm, and has a problem that the shape is complicated and the size is increased. In addition, since the conductive portion has high rigidity, it is necessary to interpose a conductive and elastic member such as carbon paper, which complicates the operation and is not economical.

  The present invention solves this type of problem, and it is possible to measure the surface pressure distribution in the fuel cell stack with high accuracy and reliability with a compact and economical configuration and ensuring good adhesion. An object is to provide a fuel cell system.

  The present invention includes a fuel cell stack having an electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of an electrolyte, and a power generation cell having the electrolyte / electrode structure and a separator, and the fuel cell. The present invention relates to a fuel cell system including a capacitance type surface pressure measuring device disposed in a stack and measuring the surface pressure of the power generation cell.

  In this fuel cell system, the capacitance-type surface pressure measuring device includes a plurality of dielectrics provided in the power generation surface of the power generation cell, and extends along the power generation surface direction of the power generation cell. And a lattice-shaped conductive portion that allows current to flow in the stacking direction between the dielectrics, and the lattice-shaped conductive portion is provided with a thin portion that is thin in the thickness direction at at least one of the lattice intersections. .

  Further, in this fuel cell system, the grid-like conductive portion is cut out from one surface side to provide a thin portion, and the second lattice portion is cut from the other surface side to provide the thin portion. It is preferable to have a lattice intersection.

  Further, in this fuel cell system, it is preferable that the grid-like conductive portion is provided alternately with the first grid intersection and the second grid intersection adjacent to each other.

  According to the present invention, the capacitance-type surface pressure measuring device includes a grid-like conductive part that allows current to flow in the stacking direction between the dielectrics, and the grid-like conductive part includes at least one grid crossing part. Further, a thin portion is provided in the thickness direction. For this reason, the lattice crossing portion can impart spring properties to a thin portion, and the lattice-like conductive portion can be satisfactorily adhered to the surface pressure measurement portion of the fuel cell stack.

  Therefore, the capacitance-type surface pressure measuring device can effectively improve the measurement sensitivity and perform stable measurement well and reliably. As a result, it is possible to satisfactorily measure the surface pressure in the power generation surface, covering the use load region of the fuel cell stack, and to reduce the surface pressure distribution in the fuel cell stack with a compact and economical configuration. Highly accurate and reliable measurement can be performed.

1 is an explanatory perspective view of a fuel cell system according to an embodiment of the present invention. It is a cross-sectional side view of the fuel cell system. It is a disassembled perspective explanatory drawing of the electric power generation cell which comprises the said fuel cell system. It is a principal part disassembled perspective view of the electrostatic capacitance type surface pressure measuring apparatus which comprises the said fuel cell system. FIG. 4 is a partially enlarged perspective explanatory view of a grid-like conductive portion constituting the capacitance type surface pressure measuring device. It is a principal part perspective view of the said electrostatic capacitance type surface pressure measuring apparatus. It is circuit explanatory drawing of the said electrostatic capacitance type surface pressure measuring apparatus. It is a principal part disassembled perspective view of the said capacitance-type surface pressure measuring apparatus. FIG. 10 is a cross-sectional explanatory diagram of a surface pressure distribution detection device disclosed in Patent Document 1.

  As shown in FIGS. 1 and 2, a fuel cell system 10 according to an embodiment of the present invention includes a fuel cell stack 12, and a capacitance type surface pressure measuring device 14 disposed in the fuel cell stack 12. Is provided. The fuel cell system 10 is mounted on a fuel cell vehicle such as a fuel cell vehicle (not shown), for example.

  In the fuel cell stack 12, a plurality of power generation cells 16 are stacked in the direction of arrow A, and end plates 20a and 20b are arranged at both ends in the stacking direction with terminal plates 17a and 17b and insulating plates 18a and 18b interposed therebetween. (See FIG. 2).

  The end plates 20a and 20b are fastened in the stacking direction by a plurality of fastening bolts 21a, for example. The end plate 20b is formed with a screw hole (not shown) into which the fastening bolt 21a is screwed. Alternatively, a through hole may be formed in the end plate 20b, and a nut (not shown) may be screwed to the tip of the fastening bolt 21a.

  Further, a clamping load may be applied by interposing a plate (not shown) between the end plates 20a and 20b and adjusting the distance between the end plates 20a and 20b. Further, a load may be applied between the end plate 20a and the insulating plate 18a or between the end plate 20b and the insulating plate 18b via a disc spring (not shown).

  As shown in FIGS. 2 and 3, each power generation cell 16 includes an electrolyte membrane / electrode structure 22, and a first separator 24 and a second separator 26 that sandwich the electrolyte membrane / electrode structure 22. Although the 1st separator 24 and the 2nd separator 26 are comprised by the carbon separator, for example, you may use a metal separator. Between the first separator 24 and the second separator 26, the electrolyte membrane / electrode structure 22 is accommodated and a gasket 27 is interposed.

  As shown in FIG. 3, an oxidant for supplying an oxidant gas, for example, an oxygen-containing gas (such as air) to one end edge of the power generation cell 16 in the direction of arrow B and communicating with each other in the direction of arrow A. A gas supply communication hole 28a, a cooling medium supply communication hole 30a for supplying a cooling medium such as pure water or ethylene glycol, and a fuel gas discharge communication hole 32b for discharging a fuel gas such as a hydrogen-containing gas are provided. Provided.

  The other end edge of the power generation cell 16 in the direction of the arrow B communicates with each other in the direction of the arrow A, the fuel gas supply communication hole 32a for supplying the fuel gas, and the cooling medium discharge communication hole for discharging the cooling medium. 30b and an oxidant gas discharge communication hole 28b for discharging the oxidant gas are provided.

  The electrolyte membrane / electrode structure 22 includes, for example, a solid polymer electrolyte membrane 34 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode side electrode 36 and a cathode side electrode 38 that sandwich the solid polymer electrolyte membrane 34. With.

  The anode side electrode 36 and the cathode side electrode 38 are uniformly coated on the surface of the gas diffusion layer with a gas diffusion layer (not shown) made of carbon paper or the like and porous carbon particles carrying a platinum alloy on the surface. And an electrode catalyst layer (not shown) formed. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 34.

  The first separator 24 is provided with a fuel gas flow path 40 on a surface 24 a facing the electrolyte membrane / electrode structure 22. The fuel gas channel 40 has a plurality of channel grooves extending in the direction of arrow B, and communicates with the fuel gas supply communication hole 32a and the fuel gas discharge communication hole 32b. A cooling medium flow path 42 is formed on the surface 24 b of the first separator 24. The cooling medium flow path 42 has a plurality of flow path grooves extending in the direction of arrow B, and communicates with the cooling medium supply communication hole 30a and the cooling medium discharge communication hole 30b.

  In the second separator 26, an oxidant gas flow path 44 is formed on the surface 26 a facing the electrolyte membrane / electrode structure 22. The oxidant gas flow path 44 has a plurality of flow path grooves extending in the direction of arrow B, and communicates with the oxidant gas supply communication hole 28a and the oxidant gas discharge communication hole 28b. The surface 26b of the second separator 26 is configured to be flat.

  As shown in FIG. 2, the capacitance-type surface pressure measuring device 14 is arranged at the approximate center of the power generation cells 16 stacked in the fuel cell stack 12. As shown in FIGS. 4 and 5, the capacitance-type surface pressure measuring device 14 accommodates a plurality of dielectrics 50 that are located in the power generation surface of the power generation cell 16 and arranged in the directions of arrows B and C. Grid-like conductive portions 52, a plurality of first electrodes 54 and second electrodes 56 that sandwich the dielectric 50 integrally from both sides, and insulating members on the outside of the first electrodes 54 and the second electrodes 56, respectively. A first shield member 60 and a second shield member 62 are provided so as to be surrounded by 58a and 58b and stacked.

  The capacitance type surface pressure measuring device 14 constitutes a capacitance type sensor, and is formed of an insulator such as PI (polyimide), LCP (liquid crystal polymer), PET (polyethylene terephthalate), or silicone. A plurality of dielectrics 50 are provided.

The grid-like conductive part 52 extends along the direction of the power generation surface of the power generation cell 16 and is, for example, a low electrical resistance material such as silver, silver alloy, gold, gold alloy, copper, copper alloy, aluminum, or aluminum alloy ( Electrical resistivity 2 × 10 ⁻⁷ Ωm or less), or carbon paper, carbon cloth, conductive resin, or the like. The surface of the grid-like conductive portion 52 is subjected to a plating treatment with anti-oxidation gold or gold alloy as necessary.

  The grid-like conductive portion 52 has a plurality of first plate-like portions 64 extending in parallel with each other in the direction of arrow B, and a plurality of second plate-like portions 66 extending in parallel with each other in the direction of arrow C. . The first plate-like portion 64 and the second plate-like portion 66 are orthogonal to each other and are integrated at each lattice intersection 68.

  As shown in FIGS. 4 and 6, the lattice-shaped conductive portion 52 is provided with a thin portion 70 that is thin in the thickness direction (arrow A direction) at least at any lattice intersection 68. The grid-like conductive portion 52 includes a first grid intersection 68a where a thin portion 70a is provided by cutting away from a surface (one surface) facing the first electrode 54, and a surface (the other surface) facing the second electrode 56. And a second lattice intersection 68b provided with a thin portion 70b by cutting out from the surface) side.

  The grid-like conductive part 52 is preferably provided with the first grid crossing part 68a and the second grid crossing part 68b alternately adjacent to each other. That is, since the grid-like conductive portion 52 is set to a uniform thickness as a whole, for example, a flat plate can be formed by pressing.

  A plurality of first groove portions 72a extending in the arrow B direction and arranged in the arrow C direction are formed on the surface of the grid-like conductive portion 52 that faces the first electrode 54. A plurality of second groove portions 72b extending in the arrow C direction and arranged in the arrow B direction are formed on the surface of the grid-like conductive portion 52 that faces the second electrode 56. An opening 74 for disposing each dielectric 50 is provided at a portion where the first groove 72a and the second groove 72b intersect.

  The first electrode 54 is accommodated in the first groove 72 a of the grid-like conductive part 52 and is formed in a long shape in the arrow B direction. The first electrode 54 is made of, for example, copper or gold and has a thickness set to 0.1 mm or less. If necessary, it may be surrounded by an insulating film made of a polymer material (not shown).

  Similarly to the first electrode 54 described above, the second electrode 56 is accommodated in the second groove 72b of the grid-like conductive portion 52 and is formed in a long shape in the direction of arrow C (direction perpendicular to the direction of arrow B). Is done. The second electrode 56 is made of, for example, copper or gold, and has a thickness set to 0.1 mm or less, and is surrounded by an insulating film made of a polymer material (not shown) as necessary.

  The insulating member 58a is housed in the first groove 72a and has a long shape extending in the direction of the arrow B, and houses the first electrode 54 and the first shield member 60 in an insulated state. The insulating member 58b has a long shape that is accommodated in the second groove 72b and extends in the direction of arrow C, and accommodates the second electrode 56 and the second shield member 62 in an insulated state. The insulating members 58a and 58b are made of, for example, PI (polyimide), LCP (liquid crystal polymer), PET (polyethylene terephthalate) silicone, or the like.

  The first shield member 60 and the second shield member 62 are elongated metal thin plates that are accommodated in the first groove portion 72a and the second groove portion 72b and extend in directions perpendicular to each other (arrow B direction and arrow C direction), For example, it is composed of Cu (copper), Al (aluminum), or the like. All the first shield members 60 and all the second shield members 62 are electrically connected and grounded to the ground of an amplifier 96 described later.

  As shown in FIG. 5, the dielectric 50 is arrange | positioned at each opening part 74 of the grid | lattice-like electroconductive part 52, the 1st electrode 54 accommodated in the 1st groove part 72a, and the 2nd electrode accommodated in the 2nd groove part 72b. 56 are arranged in a so-called grid pattern in a direction orthogonal to each other across the dielectric 50.

  As shown in FIG. 7, in the control device 76, the first circuit pattern 78 is provided at the end of the first electrode 54, while the second circuit pattern 80 is provided at the end of the second electrode 56. . The first circuit pattern 78 includes a wiring portion 82 connected to the end portion of each first electrode 54, and the wiring portion 82 is connected to the first connector 86 via the A / D converter 84. The second circuit pattern 80 includes a wiring portion 88 connected to the end portion of each second electrode 56, and the wiring portion 88 is connected to the second connector 92 via the A / D converter 90.

  The A / D converters 84 and 90 are arranged close to each other in the plane of the grid-like conductive portion 52 in order to avoid the influence of external noise. The first connector 86 and the second connector 92 are connected to the amplifier 96.

  In the first circuit pattern 78, the plurality of wiring portions 82 have the same length and the same surface area, while in the second circuit pattern 80, the plurality of wiring portions 88 have the same length and the same surface area. Is done.

  As shown in FIG. 8, the capacitance type surface pressure measuring device 14 includes a conductive sheet (for example, carbon paper, carbon cloth, etc.) 98 on both sides, and the first separator 24 and the second separator 26. It is pinched. The capacitance-type surface pressure measuring device 14 has substantially the same dimensions (including thickness) as the electrolyte membrane / electrode structure 22 shown in FIG. 3, and between the first and second separators 24, 26. By being sandwiched between the two, the same size and shape as the power generation cell 16 are formed.

  The capacitance type surface pressure measuring device 14 has a fuel gas on the surface of the first separator 24 on the side of the capacitance type surface pressure measuring device 14 so as not to be exposed to fuel gas or oxidant gas. The supply communication hole 32a and the fuel gas discharge communication hole 32b are circulated by a resin seal (not shown), while the surface of the second separator 26 on the capacitance type surface pressure measuring device 14 side is connected to the oxidant gas supply communication. The hole 28a and the oxidizing gas discharge communication hole 28b are circulated by a resin seal (not shown).

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

  First, as shown in FIG. 2, the fuel cell stack 12 includes a plurality of power generation cells 16 stacked in the direction of arrow A, and terminal plates 17a and 17b and insulating plates 18a and 18b interposed at both ends in the stacking direction. Thus, the end plates 20a and 20b are arranged. The end plates 20a and 20b are tightened in the stacking direction by a plurality of tightening bolts 21a, and an initial load is applied. For this reason, an initial load is applied to the fuel cell stack 12 in the stacking direction, and the dielectric 50 is compressed and deformed.

  Next, as shown in FIG. 1, the oxidant gas is supplied to the oxidant gas supply communication hole 28 a of the fuel cell stack 12, while the fuel gas is supplied to the fuel gas supply communication hole 32 a of the fuel cell stack 12. Is done. Further, the cooling medium is supplied to the cooling medium supply communication hole 30 a of the fuel cell stack 12.

  In the fuel cell stack 12, as shown in FIG. 3, the oxidant gas is introduced into the oxidant gas flow path 44 of the second separator 26 from the oxidant gas supply communication hole 28 a, and the electrolyte membrane / electrode structure 22. It moves along the cathode side electrode 38. On the other hand, the fuel gas is introduced into the fuel gas flow path 40 of the first separator 24 from the fuel gas supply communication hole 32 a and moves along the anode side electrode 36 of the electrolyte membrane / electrode structure 22.

  Therefore, in each electrolyte membrane / electrode structure 22, the oxidant gas supplied to the cathode side electrode 38 and the fuel gas supplied to the anode side electrode 36 are consumed by an electrochemical reaction in the electrode catalyst layer, Power generation is performed.

  Next, the oxidant gas supplied and consumed to the cathode side electrode 38 flows along the oxidant gas discharge communication hole 28b, and is then discharged to the end plate 20a. Similarly, the fuel gas consumed by being supplied to the anode side electrode 36 is discharged to the fuel gas discharge communication hole 32b, flows, and then discharged to the end plate 20a.

  In addition, a cooling medium such as pure water or ethylene glycol is introduced into the cooling medium flow path 42 between the first separator 24 and the second separator 26 and then flows along the arrow B direction. The cooling medium cools the electrolyte membrane / electrode structure 22, then moves to the cooling medium discharge communication hole 30 b, and is discharged to the end plate 20 a for circulation.

  In this case, in the present embodiment, as shown in FIGS. 4 to 6, the lattice-shaped conductive portion 52 has at least one lattice intersection portion 68 provided with a thin portion 70 thin in the thickness direction (arrow A direction). Is provided. Therefore, in the thin portion 70, the rigidity is lowered and the spring property is improved, and the shape of the surface pressure measurement portion can be easily followed.

  In addition, the grid-like conductive portion 52 is cut from the surface facing the first electrode 54 and provided with a thin portion 70a, and the grid-like conductive portion 52 is cut from the surface facing the second electrode 56 and is thin. And a second lattice intersection 68b provided with a portion 70b. Further, the grid-like conductive portion 52 is provided with the first grid intersection 68a and the second grid intersection 68b alternately adjacent to each other.

  For this reason, the grid-like conductive part 52 can have a desired spring property as a whole, and an effect that it can be satisfactorily adhered to the surface pressure measurement portion of the fuel cell stack 12 is obtained.

  Therefore, the capacitance-type surface pressure measuring device 14 can effectively improve measurement sensitivity and perform stable measurement well and reliably. As a result, it is possible to satisfactorily measure the surface pressure in the power generation surface covering the use load region of the fuel cell stack 12, and the surface pressure in the fuel cell stack 12 can be achieved with a compact and economical configuration. The distribution can be measured with high accuracy and reliability.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell system 12 ... Fuel cell stack 14 ... Capacitance type surface pressure measuring device 16 ... Power generation cell 22 ... Electrolyte membrane and electrode structure 24, 26 ... Separator 34 ... Solid polymer electrolyte membrane 36 ... Anode side electrode 38 ... Cathode side electrode 40 ... Fuel gas flow path 42 ... Cooling medium flow path 44 ... Oxidant gas flow path 50 ... Dielectric 52 ... Grid-shaped conductive parts 54 and 56 ... Electrodes 58a and 58b ... Insulating members 60 and 62 ... Shield members 64, 66 ... plate-like parts 68, 68a, 68b ... lattice crossing parts 70, 70a, 70b ... thin-walled parts 74 ... openings

Claims (3)

A fuel cell stack having an electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of the electrolyte, and a power generation cell having the electrolyte / electrode structure and a separator, and a fuel cell stack disposed in the fuel cell stack; A fuel cell system provided with a capacitance type surface pressure measuring device for measuring the surface pressure of the power generation cell,
The capacitance-type surface pressure measuring device includes a plurality of dielectrics provided in a power generation surface of the power generation cell,
A grid-like conductive part that extends along the power generation surface direction of the power generation cell and flows a current between the dielectrics in the stacking direction;
With
In the fuel cell system, the grid-like conductive portion is provided with a thin portion that is thin in the thickness direction at least at any grid intersection. 2. The fuel cell system according to claim 1, wherein the grid-like conductive portion is cut out from one surface side and the thin-walled portion is provided;
A second lattice intersection where the thinned portion is provided by cutting out from the other surface side;
A fuel cell system comprising:   3. The fuel cell system according to claim 2, wherein the grid-like conductive portion is provided with the first grid intersection and the second grid intersection alternately adjacent to each other.

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