JP2012113847A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high performance fuel cell stack in which surface pressure distribution in the fuel cell stack can be measured reliably with high accuracy.SOLUTION: A capacitance type surface pressure measurement device 14 configuring a fuel cell system 10 comprises a plurality of dielectrics 50 provided to be located in the power generation surface of a power generation cell 16, a conductive part 52 extending in the direction of the power generation surface of the power generation cell 16, and formed thinner than the thickness of the dielectrics 50 in the lamination direction in order to feed a current between the dielectrics 50 in the lamination direction, and an initial load imparting mechanism 21 which imparts a load to a fuel cell stack 12 in the lamination direction when surface pressure measurement in the power generation surface is started, and which compresses the dielectrics 50 to have the same thickness as that of the conductive part 52.

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 (hereinafter also referred to as 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, respectively. ) Is held by a separator. 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 vehicle.

  In this fuel cell stack, a clamping load is applied between the 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 in the fuel cell stack. For example, a fuel cell stack disclosed in Patent Document 1 is known. As shown in FIG. 10, the fuel cell stack includes a surface pressure sensor module 1, and the surface pressure sensor module 1 is provided at an arbitrary position in the stacking direction of fuel cells (not shown), for example, approximately in the center. ing. In the surface pressure sensor module 1, a surface pressure sensor 4 is disposed between a pair of separators 2 via a recess 3.

  The surface pressure sensor 4 is configured by covering a capacitor type or strain gauge sensor 5 with a resin 6. For example, two surface pressure sensors 4 are sandwiched between the separators 2, and the surface pressure distribution in the fuel cell can be measured via the surface pressure sensor 4.

JP 2006-120346 A

  However, in Patent Document 1 described above, the pair of separators 2 constituting the surface pressure sensor module 1 are provided with the recesses 3 for disposing the surface pressure sensor 4, and the separators used for other fuel cells Have different configurations. Therefore, a dedicated separator 2 must be prepared for the surface pressure sensor module 1, which is not economical.

  Further, although it is described that two or more surface pressure sensors 4 are arranged in the surface of the separator 2, this type of surface pressure sensor 4 covers the sensor 5 with a resin 6 and leads 7. Is provided. For this reason, it is substantially difficult to dispose a large number of surface pressure sensors 4 in the surface of the separator 2, and there is a problem that the surface pressure in the power generation surface cannot be measured with high accuracy.

  On the other hand, normally, when a large number of sensors are arranged, normal current distribution during power generation is hindered. As a result, a large current may be applied locally, and damage due to Joule heat may occur.

  The present invention solves this type of problem, and provides a fuel cell system capable of measuring the surface pressure distribution in the fuel cell stack with high accuracy and reliability and capable of obtaining a high-performance fuel cell stack. The purpose is to provide.

  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. A conductive portion that is set to be thinner than the thickness of the dielectric in the stacking direction and allows current to flow between the dielectrics in the stacking direction, and when the surface pressure measurement in the power generation surface is started, the fuel cell stack An initial load applying mechanism that applies a load in the stacking direction and compresses the thickness of the dielectric to the same thickness as the conductive portion;

  According to the present invention, in the capacitance type surface pressure measuring device, the thickness of the dielectric in the stacking direction is set to be thicker than the thickness of the conductive portion in the stacking direction. For this reason, when an initial load is applied to the fuel cell stack in the stacking direction via the initial load applying mechanism, the derivative is compressively deformed. Therefore, in the state where the thickness of the dielectric is the same as the thickness of the conductive portion, the output sensitivity is improved due to the change in the thickness of the dielectric, and the conductive portion ensures current in the stacking direction. Can be shed.

  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. For this reason, a normal current is not inhibited during power generation, and the surface pressure distribution in the fuel cell stack can be measured with high accuracy and reliability.

1 is an explanatory perspective view of a fuel cell system according to an embodiment of the present invention. It is a partial cross section explanatory 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. It is a principal part perspective view of the said electrostatic capacitance type surface pressure measuring apparatus. FIG. 6 is a cross-sectional view of the capacitance-type surface pressure measuring device taken along line VI-VI in FIG. 5. FIG. 5 is an explanatory diagram of a relationship between a thickness of a dielectric constituting the capacitance type surface pressure measuring device and a usable area. FIG. 5 is an explanatory diagram of the relationship between the Young's modulus of the dielectric and the usable area. It is a principal part disassembled perspective view of the said capacitance-type surface pressure measuring apparatus. 1 is a cross-sectional view of a main part of a fuel cell system disclosed in Patent Document 1. FIG.

  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.

  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 tightened in the stacking direction by, for example, a plurality of tightening bolts 21a constituting the initial load applying mechanism 21. 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 (air, etc.) to one end edge of the power generation cell 16 in the direction of arrow B and in communication with 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 FIG. 4, the capacitance-type surface pressure measuring device 14 is a conductive part that accommodates a plurality of dielectrics 50 arranged in the power generation surface of the power generation cell 16 and arranged in the arrow B direction and the arrow C direction. 52, and a first electrode portion 54 and a second electrode portion 56 that sandwich the dielectric 50 integrally from both sides.

  The electrostatic capacitance type surface pressure measuring device 14 constitutes an electrostatic capacitance sensor, and is provided with a plurality of dielectrics 50 formed of an insulator such as polypropylene or polyester, for example.

The conductive portion 52 is a rectangular conductive member that extends along the power generation surface direction of the power generation cell 16 and is, for example, a low-electricity material such as silver, silver alloy, gold, gold alloy, copper, copper alloy, aluminum, or aluminum alloy. It is composed of a resistance material (electric resistivity 2 × 10 ⁻⁷ Ωm or less). The surface of the conductive portion 52 is subjected to a plating process using gold for prevention of oxidation or a gold alloy as necessary.

  A plurality of first groove portions 58a extending in the arrow B direction and arranged in the arrow C direction are formed on the surface 52a of the conductive portion 52 facing the first electrode portion 54. A plurality of second groove portions 58b extending in the arrow C direction and arranged in the arrow B direction are formed on the surface 52b of the conductive portion 52 facing the second electrode portion 56.

  The total depth of the first groove portion 58 a and the second groove portion 58 b is set to a dimension larger than the thickness of the conductive portion 52. An opening 60 for disposing each dielectric 50 is provided at a portion where the first groove 58a and the second groove 58b intersect.

  The first electrode portion 54 is provided with a plurality of elongated first electrodes 62 accommodated in the first groove portion 58 a of the conductive portion 52. The first electrode 62 is made of, for example, copper or gold, 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.

  Similar to the first electrode portion 54 described above, the second electrode portion 56 includes a plurality of elongated second electrodes 64 that are accommodated in the second groove portions 58 b of the conductive portion 52. The second electrode 64 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 first electrode 62 and the second electrode 64 are each connected to an external control device 66 via a connector (not shown) (see FIG. 1).

  As shown in FIG. 5, the dielectric 50 is arrange | positioned at each opening part 60 of the electroconductive part 52, the 1st electrode 62 accommodated in the 1st groove part 58a, and the 2nd electrode 64 accommodated in the 2nd groove part 58b, Are arranged in a so-called grid pattern in a direction perpendicular to each other across the dielectric 50.

  As shown in FIGS. 5 and 6, the thickness t1 of the dielectric 50 in the stacking direction (arrow A direction) is set to be thicker (t1> t2) than the thickness t2 of the conductive portion 52 in the stacking direction. The Both surfaces of the dielectric 50 in the stacking direction are disposed so as to protrude outward from both surfaces of the conductive portion 52 in the stacking direction.

  The thickness t1 of the dielectric 50 is set corresponding to a use load region (more than a load Pmin described later) of the fuel cell stack 12. Specifically, the electrostatic capacitance type surface pressure measuring device 14a in which the thickness t1 is set to be considerably thick (t1> t2), and the electrostatic capacitance in which the thickness t1 is set to be relatively thin (t1> t2). FIG. 7 shows a usable state of the capacitive surface pressure measurement device 14a and the capacitance surface pressure measurement device 14c in which the thickness t1 is set to be thinner than the thickness t2 (t1 <t2).

  The capacitance-type surface pressure measuring device 14a cannot be used because the current supply by the conductive portion 52 is not started even when the minimum value (load Pmin) of the use load region of the fuel cell stack 12 is exceeded. On the other hand, in the capacitance-type surface pressure measuring device 14c, the surface pressure detection processing cannot be performed because the dielectric 50 does not receive a load.

  On the other hand, in the capacitance type surface pressure measuring device 14b, the surface pressure detection processing by the dielectric 50 is already possible with the load P1 (<load Pmin) before entering the use load region of the fuel cell stack 12. This capacitance type surface pressure measuring device 14b is employed.

  In addition, the Young's modulus of the dielectric 50 is set. As shown in FIG. 8, the capacitance-type surface pressure measurement device 14b1 having a low Young's modulus of the dielectric 50 and the capacitance-type surface pressure measurement device 14b2 having a high Young's modulus of the dielectric 50 have each The deformation state of the dielectric 50 is different.

  In the capacitance-type surface pressure measuring device 14b2, the dielectric 50 is not easily deformed, and even if the minimum value (load Pmin) of the use load region of the fuel cell stack 12 is exceeded, the current supply by the conductive portion 52 is not started. Can not be used.

  On the other hand, in the electrostatic capacitance type surface pressure measuring device 14b1, the surface pressure detection processing by the dielectric 50 is already possible with the load P2 (<load Pmin) before entering the use load region of the fuel cell stack 12. This capacitance type surface pressure measuring device 14b1 is employed. That is, the dielectric 50 needs to have the thickness t1 and Young's modulus set to predetermined values (ranges).

  As shown in FIG. 9, the capacitance type surface pressure measuring device 14 includes a conductive sheet (for example, carbon paper, carbon cloth, etc.) 68 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. 1, 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.

  Next, 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. 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 this embodiment, as shown in FIGS. 5 and 6, the thickness t1 of the dielectric 50 in the stacking direction is set to be thicker than the thickness t2 of the conductive portion 52 in the stacking direction. Yes. For this reason, when the initial load is applied to the fuel cell stack 12 in the stacking direction via the initial load applying mechanism 21, the dielectric 50 is compressed and deformed.

  Therefore, in the state where the thickness t1 of the dielectric 50 is the same as the thickness t2 of the conductive portion 52, the output sensitivity due to the thickness change of the dielectric 50 is improved, and the conductive portion 52 is The current can be surely passed in the stacking direction.

  At this time, as shown in FIG. 7, in the capacitance type surface pressure measuring device 14 (14 b), the predetermined thickness t <b> 1 is set, so that the load P <b> 1 before entering the use load region of the fuel cell stack 12 ( With <load Pmin), the surface pressure detection process using the dielectric 50 is already possible. Moreover, as shown in FIG. 8, in the capacitance type surface pressure measuring device 14 (14b1), a predetermined Young's modulus is set, so that the load P2 before entering the use load region of the fuel cell stack 12 (<load Pmin), the surface pressure detection process using the dielectric 50 is already possible.

  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. For this reason, the normal current is not inhibited during power generation, and the effect that the surface pressure distribution in the fuel cell stack 12 can be measured with high accuracy and reliability is obtained.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell system 12 ... Fuel cell stack 14 ... Capacitance type surface pressure measuring device 16 ... Power generation cell 21 ... Initial load application mechanism 21a ... Clamping bolt 22 ... Electrolyte / electrode structure 24, 26 ... Separator 34 ... Solid height Molecular electrolyte membrane 36 ... Anode side electrode 38 ... Cathode side electrode 40 ... Fuel gas channel 42 ... Coolant flow channel 44 ... Oxidant gas channel 50 ... Dielectric material 52 ... Conducting part 54, 56 ... Electrode part 58a, 58b ... Groove 60 ... Opening 62, 64 ... Electrode 68 ... Conductive sheet

Claims (1)

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 conductive portion that extends along the power generation surface direction of the power generation cell, is set to be thinner than the thickness in the stacking direction of the dielectric, and allows a current to flow between the dielectrics in the stacking direction;
When starting the measurement of the surface pressure in the power generation surface, an initial load is applied to the fuel cell stack in the stacking direction, and the thickness of the dielectric is compressed to the same thickness as the conductive portion. Granting mechanism;
A fuel cell system comprising:

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