JP2014026941A - Fuel cell and method for operating fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a fuel cell in which a cell voltage can be detected and a power generation condition can be more accurately detected by simply detecting the uneven distribution of a current density distribution in a separator, so that an operational state where deterioration in a fuel cell is prevented can be maintained and durability can be improved; and a method for operating a fuel cell.SOLUTION: The fuel cell includes a first cell voltage terminal 120 and a second cell voltage terminal 122 detecting a cell voltage value V of a power generation cell 12. The first cell voltage terminal 120 is provided around an oxidant gas inlet communication hole 36a in a first separator 24A of a pair of separators, and the second voltage terminal 122 is provided around an oxidant gas outlet communication hole 36b in a second separator 24B.

Description

  The present invention provides a fuel in which an electrolyte membrane / electrode structure provided with a pair of electrodes on both sides of an electrolyte membrane and a separator are stacked, and a reactive gas flow path for supplying a reactive gas along the electrode surface is formed on the separator. The present invention relates to a battery and a method for operating the fuel cell.

  For example, a polymer electrolyte fuel cell employs an electrolyte membrane (electrolyte) made of a polymer ion exchange membrane. An electrolyte membrane / electrode structure in which an anode side electrode and a cathode side electrode are provided on both sides of the electrolyte membrane includes a unit cell sandwiched by separators. Usually, a fuel cell is configured by stacking a plurality of unit cells.

  In this unit cell, a fuel gas, for example, a gas mainly containing hydrogen (hereinafter also referred to as hydrogen-containing gas) is supplied to the anode side electrode, while an oxidant gas, for example, A gas or air mainly containing oxygen (hereinafter also referred to as oxygen-containing gas) is supplied. In the fuel gas supplied to the anode side electrode, hydrogen is ionized on the electrode catalyst and moves to the cathode side electrode side through the electrolyte membrane. Electrons generated during that time are taken out to an external circuit and used as direct current electric energy.

  By the way, in the fuel cell, it is necessary to detect whether each unit cell has a desired power generation performance. For this reason, in general, an operation of detecting a cell voltage for each unit cell or a predetermined number of unit cells at the time of power generation by connecting a cell voltage terminal provided in the separator to the voltage detection device is performed.

  And as an installation position of the cell voltage terminal to a separator, patent documents 1-4 have a statement, for example.

  Patent Document 1 discloses an example in which a protrusion for connecting a voltage monitor terminal for detecting the voltage of the unit cell 1 is provided on one side surface (near the air discharge manifold) of the cathode separator, or two adjacent ones of the cathode separator. An example provided on the side surface (near the air discharge manifold) and an example provided on two opposite side surfaces (near the air discharge manifold and near the hydrogen introduction manifold) of the cathode separator are disclosed.

  In Patent Document 2, an example in which a cell voltage terminal is provided in the vicinity of each inlet of fuel gas in a pair of separators constituting a unit cell, or between the vicinity of an inlet of oxidant gas and the vicinity of the inlet of fuel gas in a pair of separators. An example in which a cell voltage terminal is provided between each is disclosed.

  Patent Document 3 discloses an example in which a cell voltage terminal is provided in the vicinity of or near the outlet of the fuel gas in one of the pair of separators.

  In Patent Document 4, at least a part of the outer periphery of the cathode current collector is provided with two terminals for taking out the generated current in the membrane-electrode assembly, and at least a part of the outer periphery of the anode current collector, An example is disclosed in which two terminals for taking out the generated current in the membrane-electrode assembly are provided, and in particular, these terminals are arranged on the inlet side of the gas channel in the gas channel direction.

JP 2006-269333 A JP 2009-266410 A JP 2006-120572 A JP 2010-097757 A

  By the way, in conventional fuel cells such as Patent Documents 1 to 4, a cell voltage terminal is provided at a specific portion of the separator constituting the unit cell (for example, in the vicinity of the inlet of the oxidant gas), and the voltage between the adjacent cell voltage terminals, That is, the voltage of each unit cell is detected by measuring the potential difference between adjacent separators.

Therefore, when the potential of each separator between the negative electrode and the positive electrode of the fuel cell is confirmed, if the above-mentioned specific portion provided with the cell voltage terminal is near the inlet of the oxidant gas, as shown in FIGS. , the potential Va _1, Va 2 near the inlet of the oxidant gas _separators, just only · · · Va _n is known, it is impossible to confirm the uneven distribution of the current density distribution in the same separator.

For example, there is no uneven distribution of current density distribution in each of the separators, the normal case, as shown in FIG. 24, the potential profile Pf 1 toward the outlet from the inlet of the oxidant gas _separators, Pf _2, · · · Pf _n Becomes almost flat. In this case (normal time), the current i flows in a direction perpendicular to the separator and does not flow in the plane of the separator. Therefore, since there is no potential difference in the plane of the separator, the potential profiles Pf ₁ , Pf ₂ ,... Pf _n are flat.

Then, in the specific separator, for example, when current concentration occurs on the cathode inlet side, as shown in FIG. 25, the current i flows in the plane of the specific separator, so that an inclined potential profile (see Pf ₄ ) is obtained. . In addition, each potential profile (see Pf ₃ and Pf ₅ ) of the separator adjacent to the specific separator where the current concentration has occurred is not flat and has a certain inclination. If power generation is continued in such a situation, a heat spot is generated at a portion where current concentration occurs, and the fuel cell is deteriorated. Therefore, it is necessary to take measures to quickly return from the abnormal state to the normal state.

  However, if a cell voltage terminal is provided at a specific location of the cathode (for example, in the vicinity of the inlet of the oxidant gas) and the cell voltage is measured, the above-mentioned abnormality cannot be detected. There is a problem that is delayed.

  The present invention solves this kind of problem, in addition to being able to detect the cell voltage, it is possible to easily detect the uneven distribution of the current density distribution of the separator and more accurately detect the power generation situation, It is an object of the present invention to provide a fuel cell capable of maintaining an operating state that prevents deterioration of the fuel cell and improving durability.

  In addition, the present invention can easily detect the uneven distribution of the current density distribution of the separator, more accurately detect the power generation state, maintain the operating state that prevents the deterioration of the fuel cell, and maintain the fuel cell. An object of the present invention is to provide a fuel cell operating method capable of improving the durability of the fuel cell.

[1] The first aspect of the present invention includes one or more electrolyte membrane / electrode structures provided with a pair of electrodes on both sides of the electrolyte membrane, and a plurality of separators arranged alternately with the electrolyte membrane / electrode structures. The present invention relates to a fuel cell having one or more unit cells sandwiched and formed with a reaction gas flow path for supplying a reaction gas along an electrode surface.

  This fuel cell has a pair of cell voltage terminals for detecting a cell voltage of a unit cell. One cell voltage terminal is provided near the inlet of the reaction gas flow path in one separator, and the other cell voltage terminal is provided near the outlet of the reaction gas flow path in the other separator.

[2] In the first aspect of the present invention, at least the one separator may be constituted by two members, and the cell voltage terminal may be provided on any one of the members.

[3] The first aspect of the present invention may be configured as follows. That is, one cell voltage terminal is provided at one first corner portion of one separator. And when the corner part diagonally related to the first corner part in one separator is set as the other corner part, the other cell voltage terminal is opposed to the other corner part in the other separator. Provided at the second corner.

[4] In the first aspect of the present invention, at least one of the separators may be constituted by two separator members, and a cooling medium flow path may be provided between the two separator members.

[5] In the first aspect of the present invention, a voltage detector that detects a voltage between one cell voltage terminal and the other cell voltage terminal in the unit cell, and a detected voltage value from the voltage detector is an upper limit voltage value And an operation control unit that performs control to increase the stoichiometry of the reaction gas to be supplied.

Here, the stoichiometric reaction gas to be supplied indicates the ratio of the actual flow rate to the theoretically required flow rate of the supplied reaction gas,
(Actual flow rate) / (Theoretical flow rate)
Say. The same applies hereinafter.

[6] In this case, the operation control unit performs control to reduce the load when the detected voltage value from the voltage detection unit exceeds the upper limit voltage or is lower than the lower limit voltage after performing the above-described control for increasing the stoichiometry. You may make it perform.

[7] In the first aspect of the present invention, a voltage difference detector that detects a voltage difference (absolute value) between each pair of cell voltage terminals in two adjacent unit cells, and a voltage difference detector from the voltage difference detector You may make it have an operation control part which performs control which raises the stoichiometry of the reaction gas to supply, when a voltage difference (absolute value) exceeds a threshold value.

[8] In this case, the operation control unit performs control to reduce the load when the voltage difference (absolute value) from the voltage difference detection unit exceeds the threshold value after performing the above-described control for increasing the stoichiometry. You may make it perform.

[9] A fuel cell operating method according to the second aspect of the present invention is the above-described fuel cell operating method according to the first aspect of the present invention. This operation method includes a voltage detection step for detecting a voltage between one cell voltage terminal and the other cell voltage terminal in a unit cell, and when the detected voltage value exceeds the upper limit voltage value or less than the lower limit voltage value. And a stoichiometric increase step for performing control to increase the stoichiometric reaction gas to be supplied.

[10] In this case, after performing the above-described control for increasing the stoichiometry, a second voltage detection step for detecting a voltage between one cell voltage terminal and the other cell voltage terminal in the unit cell, and the detected voltage When the value exceeds the upper limit voltage value or less than the lower limit voltage value, a load reduction step for performing control to reduce the load may be included.

[11] In the first aspect of the present invention described above, a voltage difference detection step for detecting a voltage difference (absolute value) between each pair of cell voltage terminals in two adjacent unit cells, and a detected voltage difference (absolute When the value exceeds a threshold value, a stoichiometric increase step for performing control to increase the stoichiometry of the reaction gas to be supplied may be included.

[12] In this case, a second voltage difference detection step of detecting a voltage difference (absolute value) between each pair of cell voltage terminals in the two adjacent unit cells after performing the above-described control for increasing the stoichiometry. And a step of performing control for reducing the load when the detected voltage difference (absolute value) exceeds a threshold value.

  In the fuel cell according to the present invention, one cell voltage terminal is provided near the inlet of the reaction gas channel in one separator, and the other cell voltage terminal is provided near the outlet of the reaction gas channel in the other separator. Yes. Therefore, the cell voltage of the unit cell can be detected from the potential difference between one cell voltage terminal and the other cell voltage terminal.

  When current concentration occurs in the separator, each potential profile of the separator and the separator adjacent to the separator becomes non-flat and has a certain inclination. In the present invention, this inclination can be reflected in the cell voltage. it can. Therefore, if a cell voltage tolerance range where current concentration does not occur is set in advance, it is possible to easily detect whether or not current concentration has occurred by monitoring whether the detected cell voltage deviates from the tolerance range. Can do.

  As described above, according to the fuel cell of the present invention, the uneven distribution of the current density distribution of the separator can be easily detected, the power generation state can be detected more accurately, and the operation state that prevents the deterioration of the fuel cell is maintained. It becomes possible to improve the durability.

  In the fuel cell and the operation method according to the present invention, when the voltage between one cell voltage terminal and the other cell voltage terminal in the unit cell is detected and the detected voltage value exceeds the upper limit voltage value or less than the lower limit voltage value. If the allowable range of the cell voltage (upper limit voltage value and lower limit voltage value) in which current concentration does not occur is set in advance by performing control to increase the stoichiometric reaction gas to be supplied, the detected cell voltage is within the allowable range. Whether or not there is a current concentration can be easily detected. In addition, when the occurrence of current concentration is detected, the stoichiometry of the reaction gas to be supplied can be raised at an early stage, so that deterioration of the fuel cell can be prevented.

  Similarly, in the fuel cell and operation method according to the present invention described above, the voltage between one cell voltage terminal and the other cell voltage terminal in the first unit cell, one cell voltage terminal and the other in the second unit cell. By detecting the difference (absolute value) from the voltage between the cell voltage terminals, and when the voltage difference (absolute value) exceeds the threshold value, control is performed to increase the stoichiometry of the reaction gas to be supplied in advance. If, for example, the upper limit value of the voltage difference (absolute value) at which concentration does not occur is set as a threshold value, it can be monitored whether the detected voltage difference (absolute value) deviates from the threshold value. The presence or absence of concentration can be easily detected. In addition, when the occurrence of current concentration is detected, the stoichiometry of the reaction gas to be supplied can be raised at an early stage, so that deterioration of the fuel cell can be prevented.

  In addition, when the stoichiometry of the reaction gas to be supplied does not return to the normal state even if the stoichiometry is increased, the control for reducing the load can be performed to more reliably prevent the deterioration of the fuel cell due to current concentration. it can.

It is a block diagram which shows the fuel cell (1st fuel cell) which concerns on 1st Embodiment. It is a disassembled schematic perspective view which shows the 1st power generation cell and the 2nd power generation cell which comprise a 1st fuel cell. It is sectional drawing on the III-III line in FIG. It is a front view which shows the structure of the one surface of a 2nd separator. It is a front view which shows the structure of the other surface of a 2nd separator. It is a front view which shows the structure of one surface of the 2nd separator member in a 1st separator. FIG. 7A to FIG. 7D show examples of the first cell voltage terminal in the vicinity of the oxidant gas inlet communication hole (first corner portion) of the first separator member (or second separator member) in the first separator (No. 1). FIG. FIG. 8A to FIG. 8C show an example of installation of the first cell voltage terminal in the vicinity of the oxidant gas inlet communication hole (first corner portion) of the first separator member (or second separator member) in the first separator (part 2). FIG. FIG. 9A to FIG. 9D are explanatory views showing an example (part 1) of an installation mode of the second cell voltage terminal in the vicinity of the oxidant gas outlet communication hole (second corner portion) of the second separator. FIG. 10A to FIG. 10C are explanatory views showing an example (part 2) of the second cell voltage terminal installed in the vicinity of the oxidant gas outlet communication hole (second corner part) of the second separator. It is a block diagram which shows the structure of the monitoring control part which concerns on a 1st form with a fuel cell stack. It is a schematic diagram which shows the fuel cell stack in a 1st fuel cell. It is explanatory drawing which shows the electric potential profile of each separator which comprises the fuel cell stack in a 1st fuel cell, and the cell voltage of each electric power generation cell. It is a flowchart which shows the operation control by the monitoring control part which concerns on a 1st form. It is a block diagram which shows the structure of the monitoring control part which concerns on a 2nd form with a fuel cell stack. It is explanatory drawing which shows the potential difference of each separator which comprises the fuel cell stack in a 1st fuel cell, and the voltage difference between adjacent electric power generation cells. It is a flowchart which shows the operation control by the monitoring control part which concerns on a 2nd form. It is a disassembled schematic perspective view which shows the 1st power generation cell and the 2nd power generation cell which comprise the fuel cell (2nd fuel cell) which concerns on 2nd Embodiment. It is a schematic diagram which shows the fuel cell stack in a 2nd fuel cell. It is explanatory drawing which shows the potential profile of each separator which comprises the fuel cell stack in a 2nd fuel cell, and the cell voltage of each power generation cell. It is explanatory drawing which shows the potential difference of each separator which comprises the fuel cell stack in a 2nd fuel cell, and the voltage difference between adjacent electric power generation cells. It is a disassembled schematic perspective view which shows the 1st power generation cell and the 2nd power generation cell which comprise the fuel cell (3rd fuel cell) which concerns on 3rd Embodiment. It is a disassembled schematic perspective view which shows the 1st power generation cell and the 2nd power generation cell which comprise the fuel cell (4th fuel cell) which concerns on 4th Embodiment. It is explanatory drawing which shows the electric potential profile of each separator of the fuel cell at the time of normal. It is explanatory drawing which shows the electric potential profile of each separator of the fuel cell at the time of abnormality.

  Embodiments of a fuel cell and a fuel cell operating method according to the present invention will be described below with reference to FIGS.

  As shown in FIG. 1, the fuel cell according to the first embodiment (hereinafter referred to as the first fuel cell 10A) has a fuel cell stack 14 in which a plurality of power generation cells 12 (unit cells) are arranged. And a monitoring control unit 16 for monitoring and controlling the fuel cell stack 14.

  The fuel cell stack 14 is configured by laminating a plurality of power generation cells 12 in the horizontal direction (arrow A direction) or the gravitational direction (arrow C direction) (in FIG. 1, an example in which they are stacked in the horizontal direction is shown). Used as a fuel cell stack. Although not shown, metal end plates 18a and 18b are disposed at both ends in the stacking direction via terminal plates and insulating plates. The fuel cell stack 14 includes a box (casing) 20 having end plates 18a and 18b as end plates, for example.

  Power extraction terminals (plus terminal 22p, minus terminal 22m) protrude from the end plates 18a, 18b outward in the stacking direction. The plus terminal 22p and the minus terminal 22m are connected to a traveling motor and accessories not shown.

  As shown in FIG. 2, the fuel cell stack 14 is specifically configured by alternately arranging two types of power generation cells 12 (first power generation cells 12A and second power generation cells 12B). The first power generation cell 12A includes a first separator 24A, a first electrolyte membrane / electrode structure (MEA) 26a, and a second separator 24B from the plus terminal 22p toward the minus terminal 22m. The second power generation cell 12B includes a second separator 24B, a second electrolyte membrane / electrode structure (MEA) 26b, and a first separator 24A from the plus terminal 22p toward the minus terminal 22m. Each first separator 24A has two separator members (a first separator member 28a and a second separator member 28b). A cooling medium flow path 52 described later is formed between the first separator member 28a and the second separator member 28b. That is, the fuel cell stack 14 has a structure (so-called thinning cooling structure) in which cooling is performed for each combination of the adjacent first power generation cell 12A and second power generation cell 12B.

  Specifically, the first separator 24A (the first separator member 28a and the second separator member 28b) and the second separator 24B are, for example, steel plate, stainless steel plate, aluminum plate, plated steel plate, or a metal surface thereof for corrosion protection. It is comprised by the metal plate which gave the surface treatment. The first separator 24A and the second separator 24B have a concavo-convex shape by pressing a metal thin plate into a wave shape. The first separator 24A and the second separator 24B may use carbon separators or the like instead of the metal separators.

  The first electrolyte membrane / electrode structure 26a and the second electrolyte membrane / electrode structure 26b include, for example, a solid polymer electrolyte membrane 30 in which a perfluorosulfonic acid thin film is impregnated with water, and the solid polymer electrolyte membrane 30. An anode side electrode 32 and a cathode side electrode 34 are provided.

  3 is a cross-sectional view taken along line III-III in FIG. As shown in FIG. 3, the anode side electrode 32 constitutes a so-called stepped MEA having a smaller surface area than the solid polymer electrolyte membrane 30 and the cathode side electrode 34. The anode side electrode 32 and the cathode side electrode 34 may have the same surface area. The solid polymer electrolyte membrane 30, the anode side electrode 32, and the cathode side electrode 34 are each provided with a cutout at the top and bottom of both ends in the direction of arrow B to reduce the surface area.

  The anode side electrode 32 and the cathode side electrode 34 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). The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 30.

  An oxidant gas, for example, an oxygen-containing gas (air or the like) is supplied to upper edge portions in the long side direction (arrow C direction) of the first separator 24A and the second separator 24B in communication with each other in the arrow A direction. An oxidant gas inlet communication hole 36a for supplying the fuel gas, for example, a fuel gas inlet communication hole 38a for supplying a hydrogen-containing gas (hydrogen gas or the like) is provided.

  An oxidant gas outlet communication hole 36b for communicating with each other in the direction of the arrow A to discharge the oxidant gas at the lower edge of the long side direction (arrow C direction) of the first separator 24A and the second separator 24B, And a fuel gas outlet communication hole 38b for discharging the fuel gas.

  A cooling medium inlet communication hole 40a is provided at one end edge of the first separator 24A and the second separator 24B in the short side direction (arrow B direction) so as to communicate with each other in the arrow A direction and supply the cooling medium. The other end edge of the first separator 24A and the second separator 24B in the short side direction is provided with a cooling medium outlet communication hole 40b for discharging the cooling medium.

  The fuel gas inlet communication hole 38a and the fuel gas outlet communication hole 38b communicate with the surface P1ap (the surface facing the second electrolyte membrane / electrode structure 26b) of the first separator member 28a on the plus terminal side of the first separator 24A. A first fuel gas flow path 44 is formed. The first fuel gas channel 44 has a plurality of wave-like channel grooves extending in the direction of arrow C. In the vicinity of the inlet (upper end) and outlet (lower end) of the first fuel gas channel 44, an inlet buffer unit 46 and an outlet buffer unit 48 each having a plurality of embosses are provided. The first fuel gas channel 44 may be constituted by a plurality of linear channel grooves extending linearly in the direction of arrow C. The same applies to the first oxidant gas flow path 56, the second fuel gas flow path 64, and the second oxidant gas flow path 74 described below.

  The inlet buffer unit 46 and the outlet buffer unit 48 function to uniformly distribute the fuel gas from the fuel gas inlet communication hole 38 a in the width direction of the first fuel gas flow path 44 and flow in the width direction of the first fuel gas flow path 44. The fuel gas to be collected is uniformly gathered in the fuel gas outlet communication hole 38b. The emboss shape can be set to various shapes such as a rod shape in addition to a circle or a rectangle, and is provided on the front and back of the first separator member 28a in the first separator 24A. The same applies to the second separator member 28b and the second separator 24B provided in the first separator 24A described below.

  The cooling medium that connects the cooling medium inlet communication hole 40a and the cooling medium outlet communication hole 40b to the negative terminal side surface P1am of the first separator 24A in the first separator member 28a (the surface facing the second separator member 28b). A flow path 52 is formed. The cooling medium flow path 52 has a back surface shape of the first fuel gas flow path 44.

  On the negative terminal side surface P2m of the second separator 24B (the surface facing the second electrolyte membrane / electrode structure 26b), as shown in FIGS. 3 and 4, the oxidant gas inlet communication hole 36a and the oxidant gas outlet are provided. A first oxidant gas flow path 56 that communicates with the communication hole 36b is formed. The first oxidant gas channel 56 has a plurality of wave-like channel grooves extending in the direction of arrow C. In the vicinity of the inlet (upper end) and the outlet (lower end) of the first oxidant gas flow channel 56, an inlet buffer unit 58 and an outlet buffer unit 60 each having a plurality of embosses are provided.

  As shown in FIG. 5, the fuel gas inlet communication hole 38a and the fuel gas outlet communication hole 38b are formed on the surface P2p (the surface facing the first electrolyte membrane / electrode structure 26a) on the plus terminal side of the second separator 24B. A second fuel gas flow path 64 that communicates is formed. The second fuel gas flow path 64 has a plurality of wave-shaped flow path grooves extending in the direction of arrow C, and in the vicinity of the inlet (upper end portion) and the outlet (lower end portion) of the second fuel gas flow path 64, respectively. An inlet buffer unit 66 and an outlet buffer unit 68 having a plurality of embosses protruding alternately on the front side and the back side are provided.

  As shown in FIG. 6, the oxidant gas inlet communication hole 36a and the oxidant gas are formed on the surface P1bm (the surface facing the first electrolyte membrane / electrode structure 26a) of the second separator member 28b on the negative terminal side of the first separator 24A. A second oxidant gas flow path 74 that communicates with the agent gas outlet communication hole 36b is formed.

  The second oxidant gas channel 74 has a plurality of wavy channel grooves extending in the direction of arrow C. In the vicinity of the inlet (upper end) and the outlet (lower end) of the second oxidant gas channel 74, an inlet buffer unit 76 and an outlet buffer unit 78 each having a plurality of embosses are provided.

  As shown in FIG. 2, a cooling medium inlet communication hole 40a and a cooling medium outlet communication hole are formed on the surface P1bp of the first separator 24A on the positive terminal side of the second separator member 28b (the surface facing the first separator member 28a). A cooling medium flow path 52 communicating with 40b is formed. The cooling medium flow path 52 is formed by superimposing the back surface shape (wave shape) of the first fuel gas flow path 44 in the first separator member 28a and the second oxidant gas flow path 74 in the second separator member 28b. .

  The first seal member 82 is integrally formed on the surfaces P1ap and P1am of the first separator member 28a in the first separator 24A so as to go around the outer peripheral edge of the first separator member 28a. Similarly, on the surfaces P1bp and P1bm of the second separator member 28b in the first separator 24A, the second seal member 84 is integrally formed around the outer peripheral edge of the second separator member 28b. A third seal member 86 is also integrally formed on the surfaces P2p and P2m of the second separator 24B around the outer peripheral edge of the second separator 24B.

  As the first to third seal members 82, 84 and 86, for example, EPDM, NBR, fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene or acrylic rubber or the like, cushion A seal member having elasticity such as a material or a packing material is used.

  As shown in FIG. 2, the first separator member 28a of the first separator 24A has an inlet-side first connection channel 88a that communicates the fuel gas inlet communication hole 38a and the first fuel gas channel 44, and a fuel gas. An outlet-side first connection channel 88 b that communicates the outlet communication hole 38 b and the first fuel gas channel 44 is provided. The inlet-side first connection channel 88a includes a plurality of outer supply holes 90a and a plurality of inner supply holes 90b.

  On the surface P1ap side of the first separator member 28a, there are provided a plurality of passages 92a that connect the fuel gas inlet communication hole 38a and the outer supply hole portions 90a. On the surface P1am side, a plurality of passages 92b that connect the outer supply hole 90a and the inner supply hole 90b are formed. Similarly, the outlet-side first connection channel 88b includes a plurality of outer discharge holes 94a and a plurality of inner discharge holes 94b.

  On the surface P1ap side of the first separator member 28a, a plurality of passages 96a that communicate the fuel gas outlet communication hole 38b and the respective outer discharge hole portions 94a are formed. On the surface P1am side, a plurality of passages 96b communicating the outer discharge hole portion 94a and the inner discharge hole portion 94b are formed.

  As shown in FIG. 4, the oxidant gas inlet communication hole 36a, the oxidant gas outlet communication hole 36b, and the first oxidant gas flow path 56 have a plurality of inlet side connection flow paths 98a and a plurality of outlets. A plurality of convex receiving portions 100a and 100b forming the side connection channel 98b are provided.

  The second separator 24B includes an inlet-side second connection channel 102a that communicates the fuel gas inlet communication hole 38a and the second fuel gas channel 64, a fuel gas outlet communication hole 38b, and the second fuel gas channel 64. And an outlet-side second connection channel 102b communicating with each other. The inlet-side second connection channel 102 a has a supply hole 104. A passage 106a that connects the fuel gas inlet communication hole 38a and the supply hole 104 is formed on the surface P2m side.

  Similarly, the outlet-side second connection channel 102b has a plurality of discharge holes 108. On the surface P2m side, a plurality of passages 106b that connect the discharge hole portion 108 to the fuel gas outlet communication hole 38b are formed.

  As shown in FIG. 6, the second separator member 28b of the first separator 24A includes a plurality of oxidant gas inlet communication holes 36a, oxidant gas outlet communication holes 36b, and a plurality of communication parts of the second oxidant gas flow path 74. A plurality of convex receiving portions 112a and 112b are provided to form the inlet-side connecting channel 110a and the plurality of outlet-side connecting channels 110b.

  As shown in FIG. 1, the end plate 18a of the fuel cell stack 14 has an oxidant gas inlet manifold 114a communicating with the oxidant gas inlet communication hole 36a and a fuel gas inlet manifold communicating with the fuel gas inlet communication hole 38a. 116a, an oxidant gas outlet manifold 114b communicating with the oxidant gas outlet communication hole 36b, and a fuel gas outlet manifold 116b communicating with the fuel gas outlet communication hole 38b are provided. The end plate 18b is provided with a cooling medium inlet manifold 118a that communicates with the cooling medium inlet communication hole 40a and a cooling medium outlet manifold 118b that communicates with the cooling medium outlet communication hole 40b.

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

  First, as shown in FIG. 2, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 36a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 38a. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 40a.

  For this reason, the oxidant gas flows from the oxidant gas inlet communication hole 36a to the second oxidant gas flow path 74 of the second separator member 28b in the first separator 24A and the first oxidant gas flow path 56 of the second separator 24B. It is introduced (see FIG. 4 and FIG. 6). The oxidant gas moves in the direction of arrow C (the direction of gravity) along the second oxidant gas flow path 74, and is supplied to the cathode side electrode 34 of the first electrolyte membrane / electrode structure 26a. It moves in the direction of arrow C along the oxidant gas flow path 56 and is supplied to the cathode electrode 34 of the second electrolyte membrane / electrode structure 26b (see FIG. 2). In other words, the first oxidant gas flow channel 56 and the second oxidant gas flow channel 74 supply the oxidant gas to the cathodes of the first electrolyte membrane / electrode structure 26a and the second electrolyte membrane / electrode structure 26b. By flowing along the surface of the side electrode 34, the oxidant gas is supplied to each cathode side electrode 34 of the first electrolyte membrane / electrode structure 26a and the second electrolyte membrane / electrode structure 26b.

  On the other hand, as shown in FIGS. 2 and 4, the fuel gas passes through the fuel gas inlet communication hole 38a into passages 92a and 106a formed between the first separator member 28a and the second separator 24B in the first separator 24A. be introduced. The fuel gas introduced into the passage 92a moves to the surface P1am side of the first separator member 28a in the first separator 24A through the outer supply hole 90a. Further, the fuel gas is introduced from the inner supply hole 90b to the surface P1ap side through the passage 92b.

  For this reason, the fuel gas is sent to the inlet buffer section 46 and moves in the direction of gravity (arrow C direction) along the first fuel gas flow path 44, and the anode side electrode 32 of the second electrolyte membrane / electrode structure 26 b. To be supplied. In the present embodiment, the oxidant gas and the fuel gas are circulated in the same direction, but may be circulated in opposite directions.

  Further, the fuel gas introduced into the passage 106a moves to the surface P2p side of the second separator 24B through the supply hole 104 as shown in FIG. For this reason, after the fuel gas is supplied to the inlet buffer 66 on the surface P2p side, the fuel gas moves along the second fuel gas flow path 64 in the direction of arrow C, and the anode side of the first electrolyte membrane / electrode structure 26a It is supplied to the electrode 32 (see FIGS. 2 and 5).

  In other words, the first fuel gas channel 44 and the second fuel gas channel 64 supply fuel gas to the anode side electrodes 32 of the first electrolyte membrane / electrode structure 26a and the second electrolyte membrane / electrode structure 26b. The fuel gas is supplied to the anode electrodes 32 of the first electrolyte membrane / electrode structure 26a and the second electrolyte membrane / electrode structure 26b.

  Therefore, in the first and second electrolyte membrane / electrode structures 26a and 26b, the oxidant gas supplied to the cathode side electrode 34 and the fuel gas supplied to the anode side electrode 32 are electrically generated in the electrode catalyst layer. It is consumed by chemical reaction to generate electricity.

  Next, the oxidant gas supplied and consumed to the cathode side electrodes 34 of the first and second electrolyte membrane / electrode structures 26a and 26b is discharged in the direction of arrow A along the oxidant gas outlet communication hole 36b. The

  As shown in FIG. 2, the fuel gas supplied to and consumed by the anode side electrode 32 of the second electrolyte membrane / electrode structure 26b passes through the inner discharge hole portion 94b from the outlet buffer portion 48 in the first separator 24A. It is led out to the surface P1am side of the first separator member 28a.

  The fuel gas led out to the surface P1am side is introduced into the outer discharge hole portion 94a and moves again to the surface P1ap side. Therefore, the fuel gas is discharged from the outer discharge hole portion 94a through the passage 96a to the fuel gas outlet communication hole 38b.

  Further, the fuel gas consumed by being supplied to the anode electrode 32 of the first electrolyte membrane / electrode structure 26a moves from the outlet buffer portion 68 through the discharge hole portion 108 to the surface P2m side. As shown in FIG. 5, the fuel gas passes through the passage 106b and is discharged to the fuel gas outlet communication hole 38b.

  On the other hand, as shown in FIG. 2, the cooling medium supplied to the cooling medium inlet communication hole 40a is a cooling medium flow path formed between the first separator member 28a and the second separator member 28b in the first separator 24A. After being introduced to 52, it circulates in the direction of arrow B. The cooling medium cools the first and second electrolyte membrane / electrode structures 26a and 26b, and then is discharged into the cooling medium outlet communication hole 40b.

  In the first fuel cell 10A, for example, as shown in FIG. 2, among the first separator members 28a of the first separators 24A, the first cell voltage terminals 120 are respectively provided near the oxidant gas inlet communication holes 36a. The second cell voltage terminal 122 is provided in the vicinity of the oxidant gas outlet communication hole 36b in each second separator 24B. The first cell voltage terminal 120 may be provided in the vicinity of the oxidizing gas inlet communication hole 36a of the second separator member 28b.

  That is, in the first power generation cell 12A, the first cell voltage terminal 120 provided in the vicinity of the oxidant gas inlet communication hole 36a of the first separator member 28a (or the second separator member 28b) in the first separator 24A is oxidized. The second cell voltage terminal 122 located near the inlet of the oxidant gas flow path and provided near the oxidant gas outlet communication hole 36b of the second separator 24B is located near the outlet of the oxidant gas flow path. Similarly, in the second power generation cell 12B, the first cell voltage terminal 120 provided in the vicinity of the oxidant gas inlet communication hole 36a of the first separator member 28a (or the second separator member 28b) has an oxidant gas flow path. The second cell voltage terminal 122 provided in the vicinity of the oxidant gas outlet communication hole 36b of the second separator 24B is located in the vicinity of the oxidant gas flow path outlet.

  In this case, the first cell voltage terminal 120 is provided in the first corner portion C1 closest to the oxidant gas inlet communication hole 36a in the first separator member 28a (or the second separator member 28b) of the first separator 24A, The second cell voltage terminal 122 is provided in the second corner portion C2 of the second separator 24B that is closest to the oxidant gas outlet communication hole 36b. That is, when the corner portion diagonally related to the first corner portion C1 (having the first cell voltage terminal 120) in the first separator member 28a (or the second separator member 28b) is set as another corner portion Ca. The second cell voltage terminal 122 is provided in the second corner portion C2 of the second separator 24B facing the other corner portion Ca.

  As a form which provides the 1st cell voltage terminal 120 in the 1st corner part C1, as shown to FIG. 7A, it is outward (horizontal direction: B direction) from one side surface La (long side) among 1st corner parts C1. The first cell voltage terminal 120 may protrude from the other side face Lb (short side) of the first corner portion C1, as shown in FIG. 7B (vertical direction: C The first cell voltage terminal 120 protruding in the direction may be provided.

  Of course, as shown in FIG. 7C, a notch 124 is provided on one side surface La (long side) of the first corner portion C1, and outward (horizontal direction: B direction) from the bottom portion 124a of the notch 124. The protruding first cell voltage terminal 120 may be provided, or as shown in FIG. 7D, a notch 124 is provided on the other side face Lb (short side) of the first corner portion C1, and the notch The first cell voltage terminal 120 protruding outward (vertical direction: C direction) from the bottom 124a of the 124 may be provided.

  Alternatively, as shown in FIGS. 8A to 8C, a notch 126 is provided across the two side surfaces La and Lb of the first corner portion C1, and outward (horizontal, vertical, or oblique direction) from the bottom 126a of the notch 126. The first cell voltage terminal 120 may be provided so as to protrude to the front).

  Similarly, as a form in which the second cell voltage terminal 122 is provided in the second corner portion C2, as shown in FIG. 9A, outward (horizontal direction) from one side face Lc (long side) of the second corner portion C2. : The second cell voltage terminal 122 projecting in the B direction), and as shown in FIG. 9B, the second corner portion C2 is outward (vertical) from the other side face Ld (short side). You may make it provide the 2nd cell voltage terminal 122 which protrudes in a direction (C direction).

  Of course, as shown in FIG. 9C, a notch 124 is provided in one side face Lc (long side) of the second corner portion C2, and outward (horizontal direction: B direction) from the bottom portion 124a of the notch 124. The protruding second cell voltage terminal 122 may be provided, or as shown in FIG. 9D, a notch 124 is provided on the other side face Ld (short side) of the second corner portion C2, and the notch A second cell voltage terminal 122 that protrudes outward (vertical direction: C direction) from the bottom portion 124a of 124 may be provided.

  Alternatively, as illustrated in FIGS. 10A to 10C, a notch 126 is provided across the two side surfaces Lc and Ld of the second corner portion C2, and outward (horizontal, vertical, or oblique direction) from the bottom 126a of the notch 126. The second cell voltage terminal 122 may be provided so as to protrude to the center.

  Each first cell voltage terminal 120 and each second cell voltage terminal 122 are electrically connected to the monitoring control unit 16 (see FIGS. 1, 11, and 15) through wiring.

  The monitoring control unit 16 has two forms (first form and second form). As shown in FIG. 11, the monitoring control unit 16 according to the first form includes a voltage detection unit 128 and a first operation control unit 130A. As shown in FIG. 15, the monitoring control unit 16 according to the second form includes a voltage difference detection unit 132 and a second operation control unit 130B.

  First, the monitoring control unit 16 according to the first embodiment will be described with reference to FIGS.

First, as schematically shown in FIG. 12, with respect to the plurality of first power generation cells 12A and the plurality of second power generation cells 12B constituting the first fuel cell 10A, the first terminal 22p is moved from the plus terminal 22p toward the minus terminal 22m. Power generation cells 12A ₁ , 12A ₂ ,... 12A _n , second power generation cells 12B ₁ , 12B ₂ ,... 12B _n are defined as a plurality of first cell voltage terminals 120 and a plurality of second cell voltage terminals 122. Are defined as first cell voltage terminals 120 ₁ , 120 ₂ ,... 120 _{n + 1} , second cell voltage terminals 122 ₁ , 122 ₂ ,... 122 _n from the plus terminal 22p toward the minus terminal 22m. the plurality of the first separator 24A and a plurality of the second separator 24B, toward the positive terminal 22p to the negative terminal 22m, the first separator 24A _{, 24A 2, ··· 24A n +} 1, the second separator _{24B 1,} 24B 2, defined as · · · 24B _n.

  The first separator member 28a and the second separator member 28b of the first separator 24A include the back surface shape (wave shape) of the first fuel gas passage 44 in the first separator member 28a and the second separator member 28b. Since the cooling medium flow path 52 is formed by overlapping the back surface shape (wave shape) of the oxidant gas flow path 74, the same potential is obtained. Accordingly, in terms of potential, the first separator member 28a and the second separator member 28b are the same, and can be regarded as one first separator 24A.

Further, in FIG. 13, the first cell voltage terminal _{120 1,} 120 2, ... ₁₂₀ each potential of the _{n + 1 Va 1, Va 2} , ··· Va n + 1 , a second cell voltage terminal ₁₂₂ 1, ₁₂₂ 2, · ... 122 each potential of the _{n Vb 1, Vb 2,} and · · · _{Vb n + 1,} the first separator _{24A 1, 24A 2, ··· 24A} n + 1 potential profile _{Pa 1,} Pa 2, and · · · _{Pa n + 1,} second separator _{24B 1, 24B 2, ··· 24B} n + 1 potential profile _{Pb 1,} Pb 2, shows a · · · Pb _n.

The voltage detector 128 detects a voltage (cell voltage) between the first cell voltage terminal 120 and the second cell voltage terminal 122. More specifically, for example, in the example of FIGS. 12 and 13, the first power generating cell 12A ₁ of the cell voltage value V1 (1), the first cell voltage terminal 120 ₁ and the second cell voltage terminal 122 ₁ between the voltage | va ₁ -Vb ₁ | detected by measuring the cell voltage value V2 of the second power generation cell 12B ₁ a (1), the second cell voltage terminal 122 ₁ and the first cell voltage terminal 120 a voltage between ₂ | Vb ₁ -Va ₂ | detected by measuring, likewise, the cell voltage value of the first power generation cell 12A _n V1 and (n), the first cell voltage terminal 120 _n and the second cell voltage voltage across the terminals 122 _n | _Va n -Vb _n | detected by measuring the cell voltage value V2 of the second power generation cell 12B _n a (n), the second cell voltage terminal 122 _n and the first cell voltage terminal _{120 n + 1} between the voltage | Vb _n −Van _{+ 1} | Detect more.

  In particular, in the first fuel cell 10A, the first cell voltage terminal 120 is provided at the first corner portion C1 of the first separator 24A near the oxidant gas inlet communication hole 36a of the first separator member 28a, and the second cell voltage terminal 122 is provided. Is provided at the second corner C2 near the oxidant gas outlet communication hole 36b of the second separator 24B, the potential appearing at the first cell voltage terminal 120 is the potential near the oxidant gas inlet communication hole 36a. The potential appearing at the second cell voltage terminal 122 is the potential near the oxidant gas outlet communication hole 36b. Therefore, when current concentration occurs in a specific separator, as shown in FIG. 13, the potential profiles of the specific separator and the separator adjacent to the specific separator are not flat and have a certain inclination. The potential change due to is reflected in the potential of the second cell voltage terminal 122. That is, the inclination of each potential profile of the specific separator where current concentration has occurred and the separator adjacent to the specific separator is reflected in the cell voltage of the power generation cell adjacent to the specific separator.

12 For example, if the current concentration in the first separator of the power generation cell 12A ₂ is generated, as shown in FIG. 13, the first power generation cell 12A ₂ of the cell voltage value V1 (2) is extremely lowered, downstream cell voltage value V2 of the second power generation cell 12B ₂ adjacent (2) is to be extremely increased with it.

  Therefore, if the cell voltage tolerance range (upper limit voltage value and lower limit voltage value) where current concentration does not occur is set in advance, whether the detected cell voltage (detection voltage value) deviates from the tolerance range is monitored. By doing so, it is possible to easily detect the occurrence of current concentration.

  On the other hand, as shown in FIG. 11, the first operation control unit 130A includes a first comparison unit 134A, a second comparison unit 134B, a first cathode stoichiometric control unit 136A, and a first load reduction control unit 138A. .

  The first comparison unit 134A compares the cell voltage value V detected by the voltage detection unit 128 with the upper limit voltage value Vtha and the lower limit voltage value Vthb of the allowable range, and the cell voltage value V exceeds the upper limit voltage value Vtha or When the voltage is lower than the lower limit voltage value Vthb, the first abnormality signal S1 is output.

  Based on the input of the first abnormality signal S1 from the first comparison unit 134A, the first cathode stoichiometric control unit 136A drives the oxidant gas supply system 140 to perform control for cathode stoichiometric up (stoichiometric rise). . This increases the flow rate of the oxidant gas.

  The second comparison unit 134B is activated after the cathode stoichiometric control by the first cathode stoichiometric control unit 136A, and the cell voltage value V detected by the voltage detection unit 128, the upper limit voltage value Vtha of the allowable range, and the lower limit voltage The second abnormality signal S2 is output when the cell voltage value V exceeds the upper limit voltage value Vtha or less than the lower limit voltage value Vthb.

  The first load reduction control unit 138A performs control to reduce the load based on the input of the second abnormal signal S2 from the second comparison unit 134B. Specifically, a process for lowering the set value Pg of the generated power is performed.

  Next, operation control of the fuel cell by the monitoring control unit 16 according to the first embodiment will be described with reference to the flowchart of FIG.

  First, in step S1 of FIG. 14, the voltage detection unit 128 detects the cell voltage values V of all the power generation cells 12, and stores the cell voltage values V of all the power generation cells 12 in a data file of a memory (not shown), for example. (Overwrite.

  In step S2, the first comparison unit 134A compares the cell voltage value V stored in the data file with the allowable ranges (the upper limit voltage value Vtha and the lower limit voltage value Vthb).

  In step S3, the first comparison unit 134A determines whether there is a cell voltage value V that deviates from the allowable range. If all the cell voltage values V are within the allowable range, the process returns to step S1, and the processes after step S1 are repeated.

  On the other hand, if there is a cell voltage value V that deviates from the allowable range, that is, if there is a cell voltage value V that exceeds the upper limit voltage value Vtha or there is a cell voltage value V that is less than the lower limit voltage value Vthb, Proceeding to S4, the first comparison unit 134A outputs the first abnormality signal S1 to the first cathode stoichiometric control unit 136A.

  In step S5, the first cathode stoichiometric control unit 136A drives the oxidant gas supply system 140 based on the input of the first abnormal signal S1 to perform control for cathode stoichiometric up. This increases the flow rate of the oxidant gas.

  Thereafter, in step S6, the voltage detection unit 128 detects the cell voltage values V of all the power generation cells 12 again and stores the cell voltage values V of all the power generation cells 12 in, for example, a data file of a memory (not shown). )

  In step S7, the second comparison unit 134B compares the cell voltage value V stored in the data file with the allowable ranges (the upper limit voltage value Vtha and the lower limit voltage value Vthb).

  In step S8, the second comparison unit 134B determines whether there is a cell voltage value V that deviates from the allowable range. If all the cell voltage values V are within the allowable range, the process returns to step S1, and the processes after step S1 are repeated.

  On the other hand, when the cell voltage value V exceeding the allowable range exists, the process proceeds to step S9, and the second abnormal signal S2 is output to the first load reduction control unit 138A.

  In step S10, the first load reduction control unit 138A performs a process of reducing the set value Pg of the generated power based on the input of the second abnormal signal S2, thereby reducing the load.

  In step S11, it is determined whether or not there is a request to end the operation of the fuel cell (power cut, maintenance request, etc.). If there is no end request, the process returns to step S1, and the processes after step S1 are repeated. At the stage when the termination request is made, the fuel cell operation control by the monitoring controller 16 according to the first embodiment is terminated.

  Next, the monitoring control unit 16 according to the second embodiment will be described with reference to FIGS.

  As shown in FIG. 15, the monitoring control unit 16 according to the second form includes a voltage difference detection unit 132 and a second operation control unit 130B.

The voltage difference detector 132 detects a voltage difference dV between each pair of cell voltage terminals 120 and 122 in two adjacent power generation cells 12. More specifically, as shown in FIG. 16, the first cell voltage terminal 120 ₁ and the cell voltage value between the second cell voltage terminal 122 ₁ V1 (1), the second cell voltage terminal 122 ₁ and the first cell by taking the difference between the cell voltage value V2 of the voltage between terminals 120 ₂ (1), the first power generating cell 12A ₁ - the voltage difference between the second power generation cell 12B ₁ (absolute value) | _{dV 11} | detects, cell voltage value between the second cell voltage terminal 122 ₁ and the first cell voltage terminal 120 ₂ V2 (1) and the first cell voltage terminal 120 ₂ and the cell voltage value between the second cell voltage terminal 122 ₂ V1 (2) , The voltage difference | dV ₁₂ | between the first power generation cell 12A ₂ and the second power generation cell 12B ₁ is detected, and similarly, the second cell voltage terminal 122 _n-1 and the first cell voltage terminal 120 cell voltage value between _n V2 and (n-1), the first cell conductive By taking the difference between the terminals 120 _n and the cell voltage value between the second cell voltage terminal 122 _n V1 _(n), the second power generation cell _{12B n-1} - a voltage difference between the first power generation cell 12A _n | dV _{n −1n} | is detected, the cell voltage value V1 (n) between the first cell voltage terminal 120 _n and the second cell voltage terminal 122 _{n, and} between the second cell voltage terminal 122 _n and the first cell voltage terminal 120 _{n + 1} . The voltage difference | dV _nn | between the first power generation cell 12A _n and the second power generation cell 12B _n is detected by taking the difference from the cell voltage value V2 (n).

For example, as shown in FIG. 16, a normal power generation cell, for example, the first generator cell 12A ₁ of the cell voltage value V1 (1) and the second power generation cell 12B ₁ of the cell voltage value V2 (1) is approximately the same voltage value Therefore, the voltage difference | dV ₁₁ | is almost 0V. Here, for example, if the current concentration occurs in the first separator of the power generation cell 12A _2, the second power generation cell 12B to the first power generation cell 12A ₂ of the cell voltage value V1 (2) is extremely lowered, adjacent to the downstream _Accordingly, the cell voltage value V2 (2) of 2 is extremely increased. Accordingly, the voltage difference between the first power generation cell 12A cell voltage value V1 (2) ₂ and the cell voltage value V2 of the second power generation cell _{12B 2 (2) | dV 22} | is greatly compared with the case of normal Will increase.

  Therefore, if, for example, the upper limit value of the voltage difference (absolute value) at which current concentration does not occur is set as the threshold value Vth, the detected voltage difference (absolute value) deviates from the threshold value Vth. By monitoring whether or not the occurrence of current concentration, it can be easily detected.

  On the other hand, as shown in FIG. 15, the second operation control unit 130B includes a third comparison unit 134C, a fourth comparison unit 134D, a second cathode stoichiometric control unit 136B, and a second load reduction control unit 138B. .

  The third comparison unit 134C compares the voltage difference (absolute value) | dV | detected by the voltage difference detection unit 132 with the threshold value Vth, and when there is a voltage difference | dV | exceeding the threshold value Vth. The third abnormal signal S3 is output.

  Based on the input of the third abnormality signal S3 from the third comparison unit 134C, the second cathode stoichiometric control unit 136B drives the oxidant gas supply system 140 to perform control for cathode stoichiometric up. This increases the flow rate of the oxidant gas.

  The fourth comparison unit 134D is activated after the cathode stoichiometric control is performed by the second cathode stoichiometric control unit 136B, and compares the voltage difference | dV | detected by the voltage difference detecting unit 132 with the threshold value Vth. When there is a voltage difference | dV | exceeding the threshold value Vth, the fourth abnormality signal S4 is output.

  The second load reduction control unit 138B performs control to reduce the load based on the input of the fourth abnormality signal S4 from the fourth comparison unit 134D. Specifically, a process for lowering the set value Pg of the generated power is performed.

  Next, operation control of the fuel cell by the monitoring control unit 16 according to the second embodiment described above will be described with reference to the flowchart of FIG.

  First, in step S101 in FIG. 17, the voltage difference detection unit 132 detects a difference in cell voltage values V (voltage difference | dV |) between all adjacent power generation cells 12, and detects all voltage differences | dV |. Is stored (overwritten) in a data file in a memory (not shown), for example.

  In step S102, the third comparison unit 134C compares the voltage difference | dV | stored in the data file with the threshold value Vth.

  In step S103, the third comparison unit 134C determines whether or not there is a voltage difference | dV | exceeding the threshold value Vth. When all the voltage differences | dV | are equal to or less than the threshold value Vth, the process returns to step S101, and the processes after step S101 are repeated.

  On the other hand, when the voltage difference | dV | exceeding the threshold value Vth exists, the process proceeds to step S104, and the third comparison unit 134C outputs the third abnormality signal S3 to the second cathode stoichiometric control unit 136B.

  In step S105, the second cathode stoichiometric control unit 136B performs control for cathode stoichiometry by driving the oxidant gas supply system 140 based on the input of the third abnormality signal S3. This increases the flow rate of the oxidant gas.

  Thereafter, in step S106, the voltage difference detection unit 132 detects again the voltage difference | dV | between all the adjacent power generation cells 12, and stores all the voltage differences | dV | in, for example, a data file of a memory (not shown). (Overwrite.

  In step S107, the fourth comparison unit 134D compares the voltage difference | dV | stored in the data file with the threshold value Vth.

  In step S108, the fourth comparison unit 134D determines whether or not there is a voltage difference | dV | exceeding the threshold value Vth. When all the voltage differences | dV | are equal to or less than the threshold value Vth, the process returns to step S101, and the processes after step S101 are repeated.

  On the other hand, if there is a voltage difference | dV | exceeding the threshold Vth, the process proceeds to step S109, and the fourth comparison unit 134D outputs the fourth abnormality signal S4 to the second load reduction control unit 138B.

  In step S110, the second load reduction control unit 138B performs a process of reducing the set value Pg of the generated power based on the input of the fourth abnormality signal S4, and performs control to reduce the load.

  In step S111, it is determined whether or not there is a request for ending the operation of the fuel cell (power interruption, maintenance request, etc.). If there is no end request, the process returns to step S101, and the processes after step S101 are repeated. When the termination request is made, the fuel cell operation control by the monitoring control unit 16 according to the second embodiment is terminated.

  As described above, in the first fuel cell 10A, the first cell voltage terminal 120 is provided near the oxidant gas inlet communication hole 36a of the first separator member 28a in the first separator 24A, and the oxidant gas outlet of the second separator 24B. The second cell voltage terminal 122 is provided in the vicinity of the communication hole 36b. Therefore, the cell voltage value V of the power generation cell 12 can be detected from the potential difference between the first cell voltage terminal 120 and the second cell voltage terminal 122.

  When current concentration occurs in, for example, the oxidant gas inlet communication hole 36a of a specific separator, the potential profiles of the specific separator and the separator adjacent to the specific separator are not flat and have a certain inclination. In the first fuel cell 10A, this inclination can be reflected in the cell voltage value V. Therefore, an allowable range (upper limit voltage value Vtha and lower limit voltage value Vthb) of the cell voltage value V where current concentration does not occur is set in advance, and it is monitored whether the detected cell voltage value V deviates from the allowable range. Thus, it is possible to easily detect whether or not current concentration has occurred.

  Alternatively, in the case of detecting a cell voltage difference (voltage difference | dV |) between two adjacent power generation cells 12, for example, an upper limit value of the voltage difference | dV | at which no current concentration occurs is set in advance as the threshold value Vth. Then, by monitoring whether or not the detected voltage difference | dV | deviates from the threshold value Vth, it is possible to easily detect whether or not current concentration has occurred.

  In addition, when the occurrence of current concentration is detected, the first operation control unit 130A or the second operation control unit 130B can perform the cathode stoichiometric up early, thereby preventing the deterioration of the fuel cell stack 14. Can do. Further, when the cathode stoichiometric up does not return to the normal state, the first operation control unit 130A or the second operation control unit 130B performs the control to reduce the load, thereby more reliably increasing the current. Degradation of the fuel cell stack 14 due to concentration can be prevented.

  That is, in the first fuel cell 10A, the uneven distribution of the current density distribution of the separator can be easily detected, and the power generation state can be detected more accurately, and the operation state that prevents the deterioration of the fuel cell stack 14 is maintained. As a result, durability can be improved.

  In particular, the first cell voltage terminal 120 is provided at the first corner C1 of the first separator member 28a of the first separator 24A closest to the oxidant gas inlet communication hole 36a, and the second cell voltage terminal 122 is Since the two separators 24B are provided at the second corner C2 closest to the oxidant gas outlet communication hole 36b, the cell voltage value V is monitored even when a current flows in the plane of a specific separator. Thus, it is possible to easily detect that current concentration has occurred.

  Further, at least one of the separators (in this example, the first separator 24A) is constituted by two separator members (the first separator member 28a and the second separator member 28b), and a cooling medium flow is provided between the two separator members. By providing the path 52, cooling is performed for each power generation cell 12 (described later) or, as described above, cooling is performed for each combination of adjacent first unit cells and second unit cells (so-called thinning cooling). Structure).

  Next, a fuel cell according to a second embodiment (hereinafter referred to as a second fuel cell 10B) will be described with reference to FIGS. 18 is an exploded perspective view corresponding to FIG. 2 (first fuel cell 10A), FIG. 19 is a schematic diagram corresponding to FIG. 12 (first fuel cell 10A), and FIG. FIG. 21 is an explanatory diagram showing an in-plane potential profile corresponding to FIG. 13 (first fuel cell 10A), and FIG. 21 is a diagram of the separator corresponding to FIG. 16 (first fuel cell 10A). It is explanatory drawing which shows an internal potential profile.

  The second fuel cell 10B has substantially the same configuration as the first fuel cell 10A described above, but the first cell voltage terminal 120 and the second cell voltage terminal 122 are installed as shown in FIGS. In the first separator member 28a (or second separator member 28b) of each first separator 24A, the second cell voltage terminal 122 is provided in the vicinity of the oxidant gas outlet communication hole 36b. The cell voltage terminal 120 is not provided), and the first cell voltage terminal 120 is provided in the vicinity of the oxidant gas inlet communication hole 36a in each second separator 24B (the second cell voltage terminal 122 is not provided).

  That is, in the first power generation cell 12A, the second cell voltage terminal 122 provided in the vicinity of the oxidant gas outlet communication hole 36b of the first separator member 28a (or the second separator member 28b) in the first separator 24A is oxidized. The first cell voltage terminal 120 provided near the oxidant gas flow path and near the oxidant gas inlet communication hole 36a of the second separator 24B is located near the oxidant gas flow path inlet. Similarly, in the second power generation cell 12B, the second cell voltage terminal 122 provided in the vicinity of the oxidant gas outlet communication hole 36b of the first separator member 28a (or the second separator member 28b) has an oxidant gas flow path. The first cell voltage terminal 120 provided near the oxidant gas inlet communication hole 36a of the second separator 24B is located near the oxidant gas flow path inlet.

  Also in the second fuel cell 10B, the first cell voltage terminal 120 and the second cell voltage terminal 122 may be provided in the same manner as shown in FIGS. 7A to 10C.

  The monitoring control unit 16 can use the monitoring control unit 16 according to the first mode in the first fuel cell 10A described above or the monitoring control unit 16 according to the second mode.

When the monitoring control unit 16 according to the first form is used, the voltage detection unit 128 detects the voltage (cell voltage value V) between the first cell voltage terminal 120 and the second cell voltage terminal 122. That is, in the example of FIG. 19 and FIG. 20, the cell voltage value of the first power generation cell 12A ₁ V1: (1), the second cell voltage terminal 122 ₁ and the first cell voltage terminal 120 ₁ between the voltage _| Vb 1 -Va ₁ | detected by measuring the second power generation cell 12B ₁ of the cell voltage value V2 of the (1), the first cell voltage terminal 120 ₁ and the second cell voltage terminal 122 ₂ between the voltage _| Va 1 -Vb ₂ | Is measured by measuring the cell voltage value V1 (n) of the first power generation cell 12A _n in the same manner as the voltage | Vb _n − between the second cell voltage terminal 122 _n and the first cell voltage terminal 120 _n. detected by measuring the cell voltage value V2 of the second power generation cell 12B _n a (n), the first cell voltage terminal 120 _n and the second cell voltage terminal _{122 n + 1} between the voltage _{| |} va _n Vb _n -Va Detected by measuring _{n + 1} | To do.

  In particular, in the second fuel cell 10B, the first cell voltage terminal 120 is provided in the first corner portion C1 near the oxidant gas inlet communication hole 36a in the second separator 24B, and the second cell voltage terminal 122 is provided in the first separator 24A. Since the first separator member 28a is provided in the second corner portion C2 near the oxidant gas outlet communication hole 36b, when current concentration occurs in a specific separator, as shown in FIG. Then, each potential profile of the separator adjacent thereto becomes non-flat and has a certain inclination, but the potential change due to this inclination is reflected in the potential of the second cell voltage terminal 122. That is, the inclination of each potential profile of the specific separator where current concentration has occurred and the separator adjacent to the specific separator is reflected in the cell voltage of the power generation cell adjacent to the specific separator.

19 For example, if the current concentration in the first separator of the power generation cell 12A ₂ occurs, the second power generation cell in which the first power generation cell 12A ₂ of the cell voltage value V1 (2) is extremely lowered, adjacent to the upstream side cell voltage value V2 of the 12B ₁ (1) is to be extremely increased accordingly.

  Therefore, if a cell voltage tolerance range that does not cause current concentration is set in advance, it is easy to detect the occurrence of current concentration by monitoring whether the detected cell voltage deviates from the tolerance range. can do.

On the other hand, when the monitoring control unit 16 according to the second embodiment is used, the voltage difference detection unit 132 detects a voltage difference dV between each pair of cell voltage terminals 120 and 122 in the two adjacent power generation cells 12. More specifically, as shown in FIG. 21, the first cell voltage terminal 120 ₁ and the cell voltage value between the second cell voltage terminal 122 ₁ V1 (1), the second cell voltage terminal 122 ₂ and the first cell by taking the difference between the cell voltage value V2 of the voltage between terminals 120 ₁ (1), the first power generating cell 12A ₁ - the voltage difference between the second power generation cell 12B ₁ (absolute value) | _{dV 11} | detects, ₂ and a second cell voltage terminal 122 cell voltage value between the first cell voltage terminal 120 ₁ V2 (1) and the first cell voltage terminal 120 ₂ and the cell voltage value between the second cell voltage terminal 122 ₂ V1 (2) , The voltage difference | dV ₁₂ | between the first power generation cell 12A ₂ and the second power generation cell 12B ₁ is detected. Similarly, the second cell voltage terminal 122 _n and the first cell voltage terminal 120 are detected. cell voltage value V2 between _n-1 and (n-1), the first cell conductive By taking the difference between the terminals 120 _n and the cell voltage value between the second cell voltage terminal 122 _n V1 _(n), the second power generation cell _{12B n-1} - a voltage difference between the first power generation cell 12A _n | dV _{n −1n} | is detected, the cell voltage value V1 (n) between the first cell voltage terminal 120 _n and the second cell voltage terminal 122 _{n, and} between the second cell voltage terminal 122 _{n + 1} and the first cell voltage terminal 120 _n The voltage difference | dV _nn | between the first power generation cell 12A _n and the second power generation cell 12B _n is detected by taking the difference from the cell voltage value V2 (n).

For example, as shown in FIG. 21, for example if the current concentration in the first separator of the power generation cell 12A ₂ occurs, the first power generation cell 12A ₂ of the cell voltage value V1 (2) is extremely lowered, the upstream side so that the cell voltage value V2 of the second power generation cell 12B ₁ adjacent (1) is extremely increased accordingly. Accordingly, the voltage difference between the second power generation cell 12B ₁ of the cell voltage value V2 (1) and the first power generation cell 12A ₂ of the cell voltage value V1 (2) | _{dV 12} | is greatly compared with the case of normal Will increase.

  Therefore, if, for example, the upper limit value of the voltage difference (absolute value) at which current concentration does not occur is set as the threshold value Vth, the detected voltage difference (absolute value) deviates from the threshold value Vth. By monitoring whether or not the occurrence of current concentration, it can be easily detected.

  Note that the configuration of the monitoring control unit 16 according to the first form and the second form and the processing operation of the operation control according to the first form and the second form are the same as those of the first fuel cell 10A, and therefore redundant description is omitted. .

  As described above, in the second fuel cell 10B as well, as in the first fuel cell 10A described above, the uneven distribution of the current density distribution of the separator can be easily detected, and the power generation state can be detected more accurately. It is possible to maintain an operation state that prevents the battery from deteriorating and to improve durability.

  Next, a fuel cell according to a third embodiment (hereinafter referred to as a third fuel cell 10C) will be described with reference to FIG.

  The third fuel cell 10C has substantially the same configuration as the first fuel cell 10A described above, but has a configuration of the fuel cell stack 14, particularly, a large number of first cell voltage terminals 120 and second cell voltage terminals 122. It is different in point.

  That is, as shown in FIG. 22, each of the first cell voltage terminals is provided in the vicinity of the oxidant gas inlet communication hole 36a in the first separator member 28a (or the second separator member 28b) and the second separator 24B of each first separator 24A. 120, and the second cell voltage terminal 122 is provided in the vicinity of the oxidizing gas outlet communication hole 36b. That is, the terminal arrangement is a combination of the terminal arrangement of the first fuel cell 10A and the terminal arrangement of the second fuel cell 10B.

  Accordingly, it is possible to appropriately select whether to use the first fuel cell 10A or the second fuel cell 10B according to the specification of the device in which the third fuel cell 10C is mounted.

  Next, a fuel cell according to a fourth embodiment (hereinafter referred to as a fourth fuel cell 10D) will be described with reference to FIG.

  The fourth fuel cell 10D has substantially the same configuration as the first fuel cell 10A described above, but differs in that the first separator 24A is provided instead of the second separator 24B, and cooling is performed for each power generation cell 12. It has a structure.

  And in this 4th fuel cell 10D, as shown in FIG. 23, when it sees with a pair of 1st separator 24A which comprises the 1st electric power generation cell 12A, it is 1st of 1st separator 24A located in the plus terminal side. The first cell voltage terminal 120 is provided in the vicinity of the oxidant gas inlet communication hole 36a of the separator member 28a (or the second separator member 28b), and the first separator member 28a (or the first separator member 28a of the first separator 24A located on the negative terminal side). Second cell voltage terminals 122 are provided in the vicinity of the oxidizing gas outlet communication hole 36b of the second separator member 28b).

  When viewed from the pair of first separators 24A constituting the second power generation cell 12B, the oxidant gas inlet communication of the first separator member 28a (or the second separator member 28b) of the first separator 24A located on the negative terminal side. First cell voltage terminals 120 are provided in the vicinity of the holes 36a, respectively, in the vicinity of the oxidant gas outlet communication hole 36b of the first separator member 28a (or the second separator member 28b) of the first separator 24A located on the positive terminal side. A second cell voltage terminal 122 is provided for each.

  Also in the fourth fuel cell 10D, the first cell voltage terminal 120 and the second cell voltage terminal 122 may be provided in the same form as that shown in FIGS. 7A to 10C.

  The monitoring control unit 16 can use the monitoring control unit 16 according to the first mode in the first fuel cell 10A described above or the monitoring control unit 16 according to the second mode.

  That is, when the monitoring control unit 16 according to the first form is used, the voltage detection unit 128 detects the voltage (cell voltage value V) between the first cell voltage terminal 120 and the second cell voltage terminal 122. As in the case of the first fuel cell 10A, if a permissible range of the cell voltage value V where current concentration does not occur is set in advance, whether or not the detected cell voltage value V deviates from the permissible range can be monitored. The presence or absence of current concentration can be easily detected.

  Further, when the monitoring control unit 16 according to the second embodiment is used, the voltage difference detection unit 132 is configured such that the voltage difference (voltage difference | dV) between each pair of cell voltage terminals 120 and 122 in the two adjacent power generation cells 12. |) Is detected. If, for example, the upper limit value of the voltage difference | dV | at which current concentration does not occur is set as the threshold value Vth, it is monitored whether the detected voltage difference | dV | deviates from the threshold value Vth. Thus, it is possible to easily detect whether or not current concentration has occurred.

  Therefore, also in the fourth fuel cell 10D, as in the first fuel cell 10A described above, the uneven distribution of the current density distribution of the separator can be easily detected, and the power generation state can be detected more accurately, and the fuel cell As a result, it is possible to maintain an operating state that prevents deterioration of the battery and to improve durability.

10A to 10D ... 1st fuel cell to 4th fuel cell 12 ... Power generation cell 12A ... 1st power generation cell 12B ... 2nd power generation cell 14 ... Fuel cell stack 16 ... Monitoring control part 22m ... Minus terminal 22p ... Plus terminal 24A ... First 1 separator 24B ... second separator 26a ... first electrolyte membrane / electrode structure 26b ... second electrolyte membrane / electrode structure 28a ... first separator member 28b ... second separator member 30 ... solid polymer electrolyte membrane 32 ... anode side Electrode 34 ... Cathode side electrode 36a ... Oxidant gas inlet communication hole 36b ... Oxidant gas outlet communication hole 38a ... Fuel gas inlet communication hole 38b ... Fuel gas outlet communication hole 40a ... Cooling medium inlet communication hole 40b ... Cooling medium outlet communication hole 44 ... 1st fuel gas flow path 52 ... Cooling medium flow path 56 ... 1st oxidant gas flow path 64 ... 2nd fuel gas flow path 74 ... 2nd oxidant Flow path 120 ... First cell voltage terminal 122 ... Second cell voltage terminal 124, 126 ... Notch 128 ... Voltage detection unit 130A ... First operation control unit 130B ... Second operation control unit 132 ... Voltage difference detection unit 134A ... First comparison unit 134B ... second comparison unit 134C ... third comparison unit 134D ... fourth comparison unit 136A ... first cathode stoichiometric control unit 136B ... second cathode stoichiometric control unit 138A ... first load reduction control unit 138B ... second Load reduction control unit 140 ... oxidant gas supply system

Claims (12)

One or more electrolyte membrane / electrode structures provided with a pair of electrodes on both sides of the electrolyte membrane, and a plurality of separators arranged alternately with the electrolyte membrane / electrode structures, and along the electrode surface A fuel cell having at least one unit cell in which a reaction gas flow path for supplying a reaction gas is formed,
A pair of cell voltage terminals for detecting a cell voltage of the unit cell;
Of the pair of separators, one separator is provided with one cell voltage terminal near the inlet of the reaction gas flow path, and the other separator has the other cell voltage terminal near the outlet of the reaction gas flow path. A fuel cell provided. The fuel cell according to claim 1, wherein
At least said one separator is comprised from two members, The said cell voltage terminal is provided in any one member, The fuel cell characterized by the above-mentioned. The fuel cell according to claim 1 or 2,
The one cell voltage terminal is provided at one first corner portion of the one separator,
When the other cell voltage terminal is a corner portion that is diagonally related to the first corner portion of the one separator, the other cell portion is connected to the other corner portion of the other separator. A fuel cell, characterized in that the fuel cell is provided in a second corner portion facing each other. The fuel cell according to any one of claims 1 to 3,
At least one of the separators is composed of two separator members, and has a coolant flow path between the two separator members. The fuel cell according to claim 1, wherein
Furthermore, a voltage detector that detects a voltage between the one cell voltage terminal and the other cell voltage terminal in the unit cell;
A fuel cell comprising: an operation control unit that performs control to increase the stoichiometry of a reaction gas to be supplied when a detection voltage value from the voltage detection unit exceeds an upper limit voltage value or less than a lower limit voltage value. The fuel cell according to claim 5, wherein
The operation control unit performs control to reduce the load when the detection voltage value from the voltage detection unit exceeds the upper limit voltage value or less than the lower limit voltage value after performing control to increase the stoichiometry. A fuel cell. The fuel cell according to claim 1, wherein
Furthermore, a voltage difference detection unit that detects a voltage difference (absolute value) between each pair of cell voltage terminals in two adjacent unit cells;
A fuel cell, comprising: an operation control unit that performs control to increase a stoichiometry of a reaction gas to be supplied when a voltage difference (absolute value) from the voltage difference detection unit exceeds a threshold value. The fuel cell according to claim 7, wherein
The operation control unit performs control to reduce a load when a voltage difference (absolute value) from the voltage difference detection unit exceeds a threshold value after performing control to increase the stoichiometry. Fuel cell. The method of operating a fuel cell according to claim 1,
A voltage detection step of detecting a voltage between the one cell voltage terminal and the other cell voltage terminal in the unit cell;
A fuel cell operating method comprising: a stoichiometric increase step for performing control to increase the stoichiometry of a reaction gas to be supplied when the detected voltage value exceeds an upper limit voltage value or less than a lower limit voltage value. The method of operating a fuel cell according to claim 9,
A second voltage detecting step of detecting a voltage between the one cell voltage terminal and the other cell voltage terminal in the unit cell after performing control for increasing the stoichiometry;
And a load reduction step of performing control to reduce the load when the detected voltage value exceeds the upper limit voltage value or less than the lower limit voltage value. The method of operating a fuel cell according to claim 1,
A voltage difference detection step of detecting a voltage difference (absolute value) between each pair of cell voltage terminals in two adjacent unit cells;
A fuel cell operating method comprising: a stoichiometric increase step for performing control to increase the stoichiometry of a reaction gas to be supplied when a detected voltage difference (absolute value) exceeds a threshold value. The method of operating a fuel cell according to claim 11,
A second voltage difference detection step of detecting a voltage difference (absolute value) between each pair of cell voltage terminals in the two adjacent unit cells after performing control to increase the stoichiometry;
And a step of performing control to reduce the load when the detected voltage difference (absolute value) exceeds a threshold value.

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