JP2012129148A - Fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery in which the contact resistance in a fuel battery stack is reduced.SOLUTION: The fuel battery comprises: a fuel battery cell main body having first and second principal faces; a first gas chamber disposed on the side of the first principal face; a second gas chamber disposed on the side of the second principal face; a current collector put in contact with the first principal face, and having a hollow part; a supplying part operable to supply gas to the hollow part, and to change the contact condition of the current collector and the first principal face; a pressure difference detector operable to detect a pressure difference between a pressure in the hollow part and a pressure in the first gas chamber; and a control part operable to control the gas supply by the supplying part based on the pressure difference.

Description

  The present invention relates to a fuel cell.

  As a fuel cell, a solid oxide fuel cell (SOFC) using a solid oxide as an electrolyte is known. The SOFC has, for example, a stack (fuel cell stack) in which a large number of fuel cell main bodies each provided with a fuel electrode and an air electrode are stacked on each surface of a plate-shaped solid electrolyte body. A fuel gas and an oxidant gas (for example, oxygen in the air) are supplied to the fuel electrode and the air electrode, respectively, to cause a chemical reaction through the solid electrolyte body.

  Here, a technology that can accelerate the temperature rise of the fuel cell stack at the time of startup is disclosed (see Patent Document 1). A hollow current collector plate with a hollow inside is used, and when the temperature rises, the hollow current collector plate is recessed by filling the cavity with a low-pressure fluid. As a result, the contact resistance of the hollow collector plate is increased, the Joule heat due to the contact resistance is increased, and the temperature of the fuel cell stack can be quickly increased.

  By the way, during the operation of the fuel cell (startup, power generation, shutdown), the electrical connection state in the fuel cell stack may be reduced due to thermal expansion and contraction due to temperature cycle and heat generation in the fuel cell stack during power generation. . That is, the physical contact within the fuel cell stack, particularly between the stacked fuel cell bodies and between the current collector and the fuel cell body deteriorates, the contact resistance increases, and the power generation efficiency of the fuel cell decreases. May be incurred.

As a method of maintaining this physical contact, it is conceivable to add an elastic member such as a ceramic spring or a heat-resistant steel spring in the fuel cell stack and apply pressure between the current collector and the fuel cell body. However, there are problems in durability such as high cost by adding an elastic member and lowering of spring property due to creep deformation of the elastic member.
It is also conceivable to pressurize the fuel cell stack from the outside with a pressing member such as a spring. However, there are problems such as an increase in heat dissipation from the heat insulating container covering the fuel cell stack and an increase in heat dissipation due to heat conduction from the pressing member.

JP 2006-164680 A

  An object of the present invention is to provide a fuel cell in which the contact resistance in the fuel cell stack is reduced.

A. A fuel cell according to an aspect of the present invention has first and second main surfaces, a first gas chamber on the first main surface side, and a second gas on the second main surface side. The chambers are respectively disposed in the fuel cell main body, the current collector in contact with the first main surface and having a hollow portion, gas is supplied to the hollow portion, and the current collector and the first Based on the pressure difference, the supply unit that changes the contact state with the main surface, the pressure difference detection unit that detects the pressure difference between the pressure in the hollow portion and the pressure in the first gas chamber, And a control unit for controlling gas supply by the unit.
By controlling the gas supply to the hollow part based on the pressure difference between the first gas chamber and the hollow part, the contact state between the fuel cell body and the current collector is maintained in an appropriate state, and the contact resistance is increased. Can be prevented.

(1) The fuel cell further includes a loss detection unit that detects a DC voltage loss between the current collector and the fuel cell body, and the control unit is based on the pressure difference and the DC voltage loss. , Gas supply may be controlled.
By controlling the gas supply to the hollow portion based on the pressure difference and the DC voltage loss, the contact state between the fuel cell body and the current collector can be maintained in a more appropriate state.

(2) The supply unit pressurizes the gas, a first pipe for supplying the pressurized gas into the hollow portion, and the pressurized gas to the first gas chamber. You may provide the 2nd pipe line to supply, and the non-return valve which is arrange | positioned in the said 2nd pipe line and prevents the backflow of the gas from the said 1st gas chamber side to the said supply part.
Due to the pressure loss at the check valve, a pressure difference is generated between the first gas chamber and the hollow portion, and an increase in contact resistance can be prevented.

(3) The supply unit pressurizes the gas, a first pipe for supplying the pressurized gas into the hollow portion, and the pressurized gas to the first gas chamber. You may provide the 2nd pipe line to supply and the needle valve which is arrange | positioned at the said 2nd pipe line and the opening degree can be adjusted.
The pressure difference between the first gas chamber and the hollow portion can be adjusted using a needle valve.

(4) The supply unit pressurizes the gas, a first pipe for supplying the pressurized gas into the hollow portion, and the pressurized gas to the first gas chamber. A second pipe to be supplied; a first valve arranged in the first pipe for adjusting the supply of the pressurized gas into the hollow part; and arranged in the first pipe and the hollow A second valve for discharging gas from the inside, and when the pressure difference is smaller than a predetermined value, the control unit opens the first valve, and the pressure difference is less than the predetermined value. If larger, the control unit may open the second valve.
Using the first and second valves, the pressure difference between the first gas chamber and the hollow portion can be adjusted over a wider range.

(5) The supply unit is disposed in the second pipe line, and includes a check valve that prevents a backflow of gas from the fuel cell body side to the supply unit, and an upstream side of the first valve. A second pressure difference detector that detects a difference between the pressure and a pressure upstream of the check valve, and when the second pressure difference is smaller than the pressure difference, the controller The gas may be pressurized by operating a pressure pump.
When the second pressure difference is smaller than the pressure difference, unnecessary operation of the pressure pump can be reduced by operating the pressure pump.

(6) Either air or fuel gas may be supplied to the first gas chamber.
You may arrange | position the electrical power collector which has a hollow part in any side of an air electrode and a fuel electrode.

B. A fuel cell according to an aspect of the present invention includes a fuel cell body having an air electrode layer, a solid electrolyte layer, and a fuel electrode layer, which are sequentially stacked, and a deformable first electrode that is in contact with the air electrode layer and is deformable. A first elastic member having a first main surface on which a collecting electrode is disposed and a second main surface; a frame member laminated on the second main surface and having an opening; A plate-like shape laminated on the frame member and having a third main surface that forms a space between the second main surface and the opening, and a gas inlet that communicates with the space and supplies gas. A second elastic member having a fourth surface on which a plurality of second current collecting electrodes that are in contact with the fuel electrode layer and are capable of being crushed and deformed are disposed.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell which aimed at reduction of the contact resistance in a fuel cell stack can be provided.

1 is a perspective view illustrating a fuel cell stack 10 according to a first embodiment. 1 is a partial cross-sectional view illustrating a fuel cell stack 10 according to a first embodiment. It is a figure which shows the internal structure of the fuel battery cell 100 (1) which concerns on 1st Embodiment. It is a top view showing the state which disassembled interconnector 111 (1) concerning a 1st embodiment. It is a partial cross section showing fuel cell stack 10x concerning a comparative example. It is a figure which shows the internal structure of the fuel battery cell 100x which concerns on a comparative example. It is a top view showing the state which decomposed | disassembled the interconnector 111x which concerns on a comparative example. It is a graph showing the measurement result of a voltage loss. It is a schematic diagram showing the whole structure of the fuel cell 1 which concerns on 1st Embodiment. It is a schematic diagram showing the whole structure of the fuel cell 1a which concerns on 2nd Embodiment. It is a flowchart showing an example of the operation | movement procedure of the fuel cell 1a. It is a schematic diagram showing the whole structure of the fuel cell 1b which concerns on 3rd Embodiment. It is a flowchart showing an example of the operation | movement procedure of the fuel cell 1b.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
The solid oxide fuel cell according to the present embodiment is a device that generates power upon receipt of fuel gas and oxidant gas.

  The fuel gas includes hydrogen, hydrocarbon as a reducing agent, mixed gas of hydrogen and hydrocarbon, fuel gas obtained by passing these gases through water at a predetermined temperature, and fuel obtained by mixing these gases with water vapor. Gas etc. are mentioned. The hydrocarbon is not particularly limited, and examples thereof include natural gas, naphtha, and coal gasification gas.

  Examples of the oxidant gas include a mixed gas of oxygen and another gas (for example, air). Further, the mixed gas may contain 80% by volume or less of an inert gas such as nitrogen and argon.

A. Structure of Fuel Cell Stack 10 The solid oxide fuel cell has a fuel cell stack 10. First, the structure of the fuel cell stack 10 will be described first. 1 and 2 are a perspective view and a partial cross-sectional view of the fuel cell stack 10.

  The fuel cell stack 10 is formed by laminating a plurality of flat plate-shaped fuel cells 100 (100 (1) to 100 (5)) which are power generation units. The fuel cells 100 (1) to 100 (5) are stacked one above the other and are electrically connected via interconnectors (current collectors) 111 (1) to 111 (6). In FIG. 2, five fuel cells 100 (1) to 100 (5) are stacked, but the number of fuel cells 100 stacked is not limited to five.

As shown in FIG. 2, the gas introduction member 80 is connected to the fuel cell 100 (1), and the pressure adjusting gas is supplied to the internal space 81 of the interconnector 111 (1). As a result, the volume of the internal space 81 is increased, pressure is applied in the fuel cell stack 10, and the contact resistance in the fuel cell stack 10 can be reduced.
In the present embodiment, the interconnectors 111 (2) to 111 (6) do not have components corresponding to the internal space 81. However, the interconnectors 111 (2) to 111 (6) may have components corresponding to the internal space 81.

  FIG. 3 shows the internal structure of the fuel cell 100 (1). As shown in FIG. 3, the fuel cell 100 (1) is a so-called fuel electrode support membrane type fuel cell, and is interposed between a pair of upper and lower metal interconnectors 111 (1) and 111 (2). , The fuel cell body 120 is disposed. A fuel gas chamber 113 and an oxidant gas chamber 114 are disposed between the fuel cell body 120 and the interconnectors 111 (1) and 111 (2).

  The fuel cell main body 120 is configured by laminating a fuel electrode (anode) 121, a solid electrolyte layer 122, a reaction preventing layer 123, and an air electrode (cathode) 124 in this order.

Examples of the material of the fuel electrode 121 include ZrO ₂ ceramics such as zirconia stabilized by at least one of metals such as Ni and Fe and rare earth elements such as Sc and Y, CeO ₂ ceramics, and the like. The mixture with at least 1 sort (s) of ceramics etc. are mentioned. Moreover, metals, such as Pt, Au, Ag, Pd, Ir, Ru, Rh, Ni, and Fe, are mentioned.

Examples of the material for the solid electrolyte layer 122 include ZrO ₂ ceramics, LaGaO ₃ ceramics, BaCeO ₃ ceramics, SrCeO ₃ ceramics, SrZrO ₃ ceramics, and CaZrO ₃ ceramics.

The reaction prevention layer 123 prevents the reaction between the solid electrolyte layer 122 and the air electrode 124. For example, a CeO ₂ oxide in which a part of Ce in CeO ₂ is substituted with a rare earth element or the like is used. it can.

  Examples of the material of the air electrode 124 include various metals, metal oxides, metal double oxides, and the like.

  A frame 130 is connected to the outer peripheral edge of the fuel cell body 120. The frame 130 includes a fuel electrode frame 131, a separator 132 (outer peripheral edge thereof), and an air electrode frame 133. The fuel electrode frame 131, the separator 132, and the air electrode frame 133 are all rectangular frame shapes. The separator 132 is joined to the fuel cell body 120 and blocks gas movement between the fuel gas chamber 113 and the oxidant gas chamber 114.

  The frame 130 includes through holes 71 to 78 through which the fixing members 61 to 68 pass, respectively. In FIG. 3, only the through holes 73 and 74 are shown. The frame 130 is connected to the through holes 73 and 74, and has communication holes 134 and 135 that communicate with the fuel gas chamber 113. The frame 130 has a communication hole (not shown) that is connected to the through holes 75 and 76 and communicates with the oxidant gas chamber 114.

  Spacers 141 and 142 are disposed between the interconnector 111 (2) and the fuel electrode frame 131 and between the air electrode frame 133 and the interconnector 111 (1), respectively. The spacer 141 is made of an insulator such as mica, and electrically insulates between the interconnector 111 (2) and the fuel electrode frame 131. The spacer 142 is made of an insulator such as mica, and electrically insulates between the air electrode frame 133 and the interconnector 111 (1).

  A fuel electrode current collecting electrode 151 and an air electrode current collecting electrode 152 are disposed between the interconnector 111 (2) and the fuel electrode 121 and between the air electrode 124 and the interconnector 111 (1), respectively. The fuel electrode collecting electrode 151 electrically connects the interconnector 111 (2) and the fuel electrode 121. The air electrode current collecting electrode 152 electrically connects the air electrode 124 and the interconnector 111 (1).

The fuel electrode current collecting electrode 151 is made of a porous metal (for example, Ni) and functions as a porous current collecting electrode. Since the fuel electrode current collecting electrode 151 is porous, it is easily crushed and, as will be described later, is deformed (collapsed) by a preliminary press or the like.
On the other hand, the air electrode current collecting electrode 152 is made of a non-porous (not porous) metal (for example, stainless steel), and the collapse at the time of preliminary pressing can be virtually ignored. The air electrode collecting electrode 152 can be made porous, and in this case, deformation due to crushing is possible at the time of preliminary pressing.

  The fixing members 61 to 68 penetrate the fuel cell stack 10 in the stacking direction. The fixing members 61 to 68 are members that are arranged along the periphery of the fuel cell stack 10 and press the fuel cell stack 10 in the stacking direction to fix them together. The fixing members 61 to 68 are respectively bolts 61b to 68b and nuts 61a to 68a. Composed.

  Bolts 61b to 68b are inserted into through holes 71 to 78 that penetrate fuel cell 1 in the stacking direction, and are fixed by nuts 61a to 68a.

  Among these, the inner diameters of the through holes 71 to 76 are set larger than the outer diameters of the shafts of the bolts 61b to 66b, so that they are sandwiched between the inner peripheral surfaces of the through holes 71 to 76 and the outer peripheral surfaces of the bolts 61b to 66b. The cylindrical space is a flow path for fuel gas and oxidant gas.

  The fixing members 61 and 62 are used as anode and cathode electrodes, respectively. The through holes 73 and 74 are used for introducing and discharging fuel gas. The through holes 75 and 76 are used for introducing and discharging the oxidizing gas. The fixing members 67 and 68 are used only for fixing.

  Each of the fixing members 63 to 66 has an opening on the nut side so that fuel gas and air (oxidant gas) can be introduced or discharged. Since the fixing members 61 and 62 are used as electrodes and the fixing members 67 and 68 are used only for fixing, ordinary nuts can be used without considering gas flow.

The fuel gas flows into the fuel gas chamber 113 from between the through hole 73 and the bolt 63b, is used for power generation, passes between the through hole 74 and the bolt 64b, and is discharged out of the fuel cell stack 10.
The oxidant gas (air) flows into the oxidant gas chamber 114 from between the through hole 75 and the bolt 65b, is used for power generation, passes between the through hole 76 and the bolt 66b, and is discharged out of the fuel cell stack 10. Is done.

B. Details of the interconnector 111 (1) The interconnector 111 (1) includes a plate-like member 111a, a frame member 111b, and an elastic member 111c.

FIG. 4 is a plan view showing the plate-like member 111a, the frame member 111b, and the elastic member 111c.
The plate-like member 111 a is substantially rectangular and has through holes 71 to 78 and a gas inlet 82. A gas introduction member 80 is connected to the gas introduction port 82, and a pressure adjusting gas is supplied into the interconnector 111 (1).

  The frame member 111 b has a substantially rectangular plate shape, and has through holes 71 to 78 and an opening 83. An internal space 81 of the interconnector 111 (1) is formed between the opening 83 and the lower surface of the plate-like member 111a and the upper surface of the elastic member 111c.

  The elastic member 111c has a substantially rectangular plate shape that can be elastically deformed, has through holes 71 to 78, and an air electrode current collecting electrode 152 is disposed at the center. Pressure adjusting gas is supplied to the internal space 81 through the gas inlet 82. By changing the gas pressure in the internal space 81, the elastic member 111c is deformed. As a result, the air electrode current collecting electrode 152 moves up and down, and the contact state (contact resistance) between the air electrode current collecting electrode 152 and the air electrode 124 changes. Note that the interconnector 111 (1) including the elastic member 111 c has electrical conductivity, and thus functions as a current collecting member similarly to the air electrode current collecting electrode 152.

  As described above, in this embodiment, the internal space 81 (hollow part) is provided in the interconnector 111 (1) (current collector), and the elastic member 111c to which the air electrode current collecting electrode 152 is attached can be elastically deformed. It is composed of a material (for example, a metal plate having an operable thickness). A gas is introduced into the internal space 81 to pressurize the fuel cell stack 10 so as to have a positive pressure, and the air electrode current collecting electrode 152 (current collector) is pressed against the fuel cell body 120. As a result, an increase in electrical resistance due to poor physical contact in the fuel cell stack 10 (between the fuel electrode current collecting electrode 151, the air electrode current collecting electrode 152, and the interconnector 111) can be prevented.

C. Fuel cell stack 10x according to a comparative example
A fuel cell stack 10x according to a comparative example will be described. FIG. 5 is a partial cross-sectional view showing a fuel cell stack 10x according to a comparative example. FIG. 6 is a diagram showing an internal structure of the fuel cell 100x according to the comparative example. FIG. 7 is a plan view illustrating a state in which the interconnector 111x according to the comparative example is disassembled. 5 to 7 according to the comparative example correspond to FIGS. 2 to 4 according to the first embodiment, respectively.

  In the fuel cell stack 10 x, the interconnector 111 x of the fuel cell 100 x (corresponding to the fuel cell 100 (1)) does not have a space corresponding to the internal space 81. That is, as shown in FIGS. 6 and 7, the interconnector 111x is composed of a plate-like member 111ax and an elastic member 111cx, and does not have a configuration corresponding to the frame member 111b.

  As a result, as shown in FIG. 5, when the fuel cell body 120 is deformed upward due to power generation and temperature cycle, for example, contact is made between the air electrode current collector electrode 152, the fuel cell body 120, and the interconnector 111. Defects are likely to occur.

D. Comparison between Example and Comparative Example (1) Interconnector 111 (1) according to Example
A specific example of the interconnector 111 (1) is shown.
For example, the interconnector 111 (1) can be configured as follows.
Plate member 111a: 10 mm thick SUS (stainless steel)
Frame member 111b: SUS with a thickness of 1 mm
Elastic member 111c: SUS with a thickness of 1 mm
The plate-like member 111a, the frame member 111b, and the elastic member 111c may be joined by brazing, or may have a laminated structure with a sealing member such as mica interposed therebetween.

(2) Interconnector 111x according to a comparative example
For example, the interconnector 111x can be configured as follows.
Plate member 111ax: SUS with a thickness of 10 mm
Elastic member 111cx: SUS with a thickness of 1 mm
The plate-like member 111ax and the elastic member 111cx may be joined by brazing, or may have a laminated structure with a sealing member such as mica interposed therebetween.

(3) Comparison of electrical characteristics of interconnectors 111 (1) and 111x of Example and Comparative Example FIG. 8 shows the DC resistance component of the uppermost cell (fuel cell 100 (1)) when the temperature cycle is repeated. It is a graph which shows the voltage loss (voltage loss) by. Graphs E0 to E4 respectively represent voltage losses in the 0th to 4th temperature cycles in the interconnector according to the example. Graphs C0 to C4 represent voltage losses in the 0th to 4th temperature cycles of the interconnector according to the comparative example, respectively.

  “Room temperature → high temperature (700 ° C.) → room temperature” was defined as one cycle of the temperature cycle, and the current from the fuel cell stack during power generation was defined as current 60 A, and voltage loss was measured.

  In the example, the voltage loss was as small as about 0.1 V, and the voltage loss was kept almost the same as the initial value (substantially constant) even when the cycle was repeated up to 4. On the other hand, in the comparative example, the voltage loss increased from the initial value of about 0.1 V to over 0.8 V by repeating the temperature cycle. Since the voltage loss exceeds 0.8 V with respect to the open circuit voltage (about 1 V) of the fuel cell stack, it can be seen that the power generation characteristics of the fuel cell stack are greatly deteriorated in the comparative example.

E. FIG. 9 is a schematic diagram showing the overall configuration of the fuel cell 1.
The fuel cell 1 includes a fuel cell stack 10, an air blower 91, a check valve 92, a flow meter 93, and a differential pressure gauge 94.

  As described above, the fuel cell stack 10 includes the interconnector 111 (1) having the internal space 81, and the supply of the pressure adjusting gas to the interconnector 111 (1) allows the fuel cell stack 10 The physical contact state can be adjusted.

  The air blower 91 supplies the fuel cell stack 10 with air as an oxidant gas and a pressure adjusting gas. That is, the air blower 91 passes through the check valve 92 and the flow meter 93 to the air chamber 114 of the fuel cell 100 (fuel cells 100 (1) to 100 (5)) of the fuel cell stack 10. Supply air as gas. The air blower 91 supplies air as pressure adjusting gas into the interconnector 111 (1) of the fuel cell 100 (1) of the fuel cell stack 10.

  The air blower 91 supplies gas to the hollow portion (inner space 81), and changes the contact state between the current collector (interconnector 111 (1)) and the first main surface (the upper surface of the fuel cell body 120). Functions as a supply unit. The air blower 91 also functions as a pressurizing pump that pressurizes the gas.

The check valve 92 is a valve for preventing a backflow of air from the air chamber 114 of the fuel battery cell 100 to the air blower 91. Since the check valve 92 is disposed on the air chamber 114 side and not on the interconnector 111 (1) side, a pressure difference is generated between the air chamber 114 and the internal space 81 of the interconnector 111 (1). (Pressure loss at check valve 92). That is, the pressure in the internal space 81 is greater than the pressure in the air chamber 114.
The differential pressure gauge 94 is a measuring instrument that measures a pressure difference between the internal space 81 and the air chamber 114, and is a pressure between the pressure in the hollow portion (internal space 81) and the pressure in the first gas chamber (air chamber 114). It functions as a pressure difference detector that detects the difference.

  In the present embodiment, the pressure loss in the check valve 92 causes a pressure difference between the internal space 81 and the air chamber 114, and the elastic member 111 c of the interconnector 111 (1) is deformed and pressed against the air electrode 124. As a result, an increase in electrical resistance due to physical contact failure can be reduced.

  By using gas for pressurization, the spring property is prevented from being deteriorated due to creep deformation, and durability reliability is improved as compared with the case of using an elastic member such as a metal spring.

A desired pressing force can be obtained by changing the pressure difference (differential pressure α) between the internal space 81 and the air chamber 114. For example, as described later, when power generation characteristics are deteriorated due to poor physical contact, the pressure difference α is increased to increase the pressing force from the elastic member 111c to the air electrode 124, thereby restoring the power generation characteristics. Can do.
Here, the pressure difference α can be increased by increasing the flow rate of air from the air blower 91. This utilizes a phenomenon in which the pressure loss generated in the check valve 92 depends on the flow rate of gas (air). That is, by increasing the air flow rate, the pressure loss at the check valve 92 increases and the pressure difference α increases.

(Second Embodiment)
A second embodiment of the present invention will be described.
FIG. 10 is a schematic diagram showing the overall configuration of the fuel cell 1a according to the second embodiment of the present invention.
The fuel cell 1a includes a fuel cell stack 10, an air blower 91, a flow meter 93, a differential pressure gauge 94, a needle valve 95, and a controller 96.

The controller 96 controls the opening degree of the needle valve 95 based on the pressure difference (differential pressure α) between the internal space 81 of the interconnector 111 (1) and the air chamber 114 measured by the differential pressure gauge 94, and makes physical contact. An increase in electrical resistance due to defects can be reduced.
The air blower 91 is controlled so that the actual air flow value (actual value) is measured and the actual air flow value theoretically calculated for the amount of power generation (theoretical value). The On the other hand, the needle valve 95 is controlled to change the pressure difference α. In this way, the degree of deformation of the elastic member 111c can be adjusted by the pressure difference α to follow the warp of the fuel cell body 120.

FIG. 11 is a flowchart showing an example of the operation procedure of the fuel cell 1a.
The controller 96 determines whether or not the differential pressure α is within a specified value range (steps S111 and S112), and controls the needle valve 95 as follows.

(1) When the differential pressure α is within a specified range (steps S112 and S113)
If the differential pressure α is within the specified range (β ≦ α ≦ γ), in principle, the opening degree of the needle valve 95 is maintained as it is. Note that the air blower 91 and the needle valve 95 are controlled in order to confirm the air flow rate and the power generation amount, and to adjust the air flow rate and the like in some cases (step S113).

(2) When the differential pressure α is smaller than the specified range (steps S121 to S124)
When the differential pressure α is smaller than the specified range (α <β), the opening degree of the needle valve 95 is reduced (step S124). If the opening degree of the needle valve 95 is the lower limit value (step S122), an error state is displayed by a display device, a voice output device, etc. (step S124). At this time, the power generation in the fuel cell 1a may be stopped.

(3) When the differential pressure α is larger than the specified range (steps S131 to S133)
When the differential pressure α is larger than the specified range (α> γ), the opening degree of the needle valve 95 is increased (step S132). If the opening degree of the needle valve 95 is the upper limit value (step S131), an error state is displayed by a display device, a voice output device or the like (step S133).

(Third embodiment)
A second embodiment of the present invention will be described.
FIG. 12 is a schematic diagram showing the overall configuration of a fuel cell 1b according to the third embodiment of the present invention.
The fuel cell 1b includes a fuel cell stack 10, an air blower 91a, a check valve 92, a flow meter 93, a differential pressure gauge 94, a controller 96, a pressure pump 91b, pressure gauges 97a and 97b, electromagnetic valves 98a and 98b, a relay 99a, 99b, having an electrical measuring instrument M.

  The air blower 91 a supplies air as an oxidant gas to the fuel cell stack 10. That is, the air blower 91 a passes through the check valve 92 and the flow meter 93 to the air chamber 114 of the fuel cell 100 (fuel cells 100 (1) to 100 (5)) of the fuel cell stack 10. Supply air as gas.

  The pressurizing pump 91b supplies air as a pressure adjusting gas to the fuel cell stack 10, and functions as a pressurizing pump that pressurizes the gas. That is, the pressurizing pump 91b supplies air as a pressure adjusting gas into the interconnector 111 (1) of the fuel cell 100 (1) of the fuel cell stack 10 via the electromagnetic valve 98a.

  The pressure gauges 97a and 97b are measuring instruments that measure the pressure in the air blower 91a and the pressurizing pump 91b, respectively. The pressure gauges 97a and 97b together function as a second pressure difference detection unit that detects the difference between the pressure upstream of the first valve and the pressure upstream of the check valve.

The electromagnetic valve 98a adjusts the flow rate of air from the pressurizing pump 91b to the interconnector 111 (1), and functions as a first valve that adjusts the supply of pressurized gas into the hollow portion.
The electromagnetic valve 98b adjusts the outflow of air from the interconnector 111 (1) to the outside, and functions as a second valve that discharges gas from the hollow portion. The pressure in the interconnector 111 (1) can be adjusted by the electromagnetic valves 98a and 98b.

  The relays 99a and 99b are controlled by the controller 96 and adjust the opening degree of the electromagnetic valves 98a and 98b.

  In the fuel cell 1a of the second embodiment, the pressure is adjusted only by the needle valve 95. On the other hand, in the fuel cell 1b, the differential pressure can be adjusted in a wider range by using the electromagnetic valves 98a and 98b.

  The electrical measuring instrument M is a measuring instrument that measures the output voltage and DC loss from the fuel cell stack 10, and functions as a loss detector that detects DC voltage loss between the current collector and the fuel cell body. Details of this will be described later.

FIG. 13 is a flowchart showing an example of the operation procedure of the fuel cell 1b.
The controller 96 determines whether or not the differential pressure is within a specified value range (steps S211 and S212), and controls the needle valve 95 as follows.

(1) When the differential pressure α is within a specified range (steps S212 to S218)
If the differential pressure is within the specified range, in principle, the opening degree of the solenoid valves 98a and 98b is maintained as it is.

  Here, when the stack voltage (output voltage from the fuel cell stack 10) is outside the predetermined range (step S213), the DC voltage loss (DC resistance (IR resistance), for example, resistance value R1 described later) is measured ( Step S214). If the DC voltage loss is greater than the specified value, the differential pressure set values β and γ are changed (steps S215 and S217). Note that step S213 (stack voltage measurement, comparison with a predetermined range) may be omitted in some cases. Details of this will be described later.

A large DC voltage loss even though the differential pressure α is within the specified range means that the state of the fuel cell stack 10 changes from the initial state, and the differential pressure within the specified range is insufficient. For this reason, the specified values β and γ (specified range) of the differential pressure α are increased. For example, as described below, a positive constant value a is added to the current specified values β0 and γ0 to obtain new specified values β1 and γ1.
β1 = β0 + a
γ1 = γ0 + a

  The new specified values β1 and γ1 are used to determine whether or not the differential pressure is within the specified range when step S212 is repeated next time. In general, when the operating time of the fuel cell stack 10 becomes longer, the internal state of the fuel cell stack 10 changes, and a larger differential pressure may be required to prevent an increase in DC voltage loss.

  If the differential pressure is greater than or equal to the upper limit value (step S216), an error state is displayed by the display device, the audio output device, etc. (step S218). At this time, the power generation in the fuel cell 1b may be stopped.

  This upper limit value defines the upper limit of the differential pressure for adjusting the physical contact state in the fuel cell stack 10, and is defined separately from the differential pressure range (β, γ). This is for preventing the prescribed value range (differential range) of the differential pressure from being changed repeatedly in step S217 and preventing the prescribed range of differential pressure from continuing to rise (stop). That is, at this time, the prescribed values β and γ of the differential pressure are larger than the upper limit value.

DC voltage loss (DC resistance) can be measured by the current interruption method.
A load is connected to the fuel cell in the power generation state, and the current α (A) and voltage V1 (V) at this time are used. Disconnect the load from the fuel cell and set the current to 0 (A). The voltage V2 (V) when a short time (about several tens of microseconds) has elapsed since the connection was released is measured. At this time, the resistance value R1 is calculated by the following equation (1).
R1 = (V2-V1) / α

  This resistance value R1 is a resistance caused by a factor having a high relaxation rate such as electrons, that is, an ohmic DC resistance (IR resistance). The possibility of increase in contact resistance can be determined by measuring the resistance value R1. That is, the DC voltage loss (DC resistance) can be defined by the resistance value R1.

  Step S213 (stack voltage measurement, comparison with a predetermined range) is placed before steps S214 and S215 because measurement using the current interruption method requires disconnection of the load. . That is, by measuring the stack voltage, the load disconnection due to the measurement of DC loss is reduced.

  In other words, step S213 may be omitted if temporary load disconnection is not a problem. Even when a method that does not require disconnection of the load is used, step S213 can be omitted.

(2) When the differential pressure α is smaller than the specified range (steps S221 to S224)
When the differential pressure α is smaller than the specified range (α <β) (step S221), the opening degree of the electromagnetic valve 98a is increased (step S223). If “pressure A <pressure B + differential pressure” (step S222), the pressurizing pump 91b is turned on (step S224), and after the pressure of the pressurizing pump 91b is increased, the opening of the solenoid valve 98a is increased. Increased (step S223).

(3) When the differential pressure α is larger than the specified range (steps S221 and S225)
When the differential pressure α is larger than the specified range (α> γ) (step S221), the opening degree of the electromagnetic valve 98b is increased (step S225).

(Other embodiments)
Embodiments of the present invention are not limited to the above-described embodiments, and can be expanded and modified. The expanded and modified embodiments are also included in the technical scope of the present invention.

(1) In the first embodiment, a controller may be added to control the air supply by the air blower 91 based on the differential pressure measured by the differential pressure gauge 94.

(2) In the above embodiment, the interconnector 111 (1) having the internal space 81 is disposed on the air electrode 124 side (air chamber 114 side). On the other hand, the interconnector 111 (1) may be disposed on the combustion electrode 121 side (combustion gas chamber 113 side). For example, the fuel cell body 120 is turned upside down in the fuel cell 100 (1).

(3) In the above embodiment, the interconnector 111 (1) having the internal space 81 is disposed only in the uppermost stage. On the other hand, an interconnector having an internal space may be arranged other than the uppermost stage (for example, the middle stage or the lowermost stage). A plurality of interconnectors having an internal space may be arranged.

DESCRIPTION OF SYMBOLS 1 Fuel cell 10 Fuel cell stack 100 Fuel cell 111 (1), 111 (2) Interconnector 111a Plate member 111ax Plate member 111b Frame member 111c Elastic member 113 Fuel gas chamber 114 Oxidant gas chamber 120 Fuel cell body 121 Fuel Electrode 122 Solid Electrolyte Layer 123 Reaction Prevention Layer 124 Air Electrode 130 Frame 131 Fuel Electrode Frame 132 Separator 133 Air Electrode Frame 134, 135 Communication Holes 141, 142 Spacer 151 Fuel Electrode Current Collecting Electrode 152 Air Electrode Current Collecting Electrode 61-68 Fixing member 61a-68a Nut 61b-68b Bolt 71-78 Through hole 80 Gas introduction member 81 Internal space 82 Gas introduction port 83 Opening 91 Air blower 91a Air blower 91b Pressurizing pump 92 Check valve 93 Flow meter 94 Differential pressure gauge 95 Needle Valve 96 Controller 97a, 97b Pressure gauge 98a, 98b Solenoid valve 99a, 99b Relay M Electrical measuring instrument

Claims (8)

A fuel cell body having first and second main surfaces, and a first gas chamber disposed on the first main surface side and a second gas chamber disposed on the second main surface side, respectively. When,
A current collector in contact with the first main surface and having a hollow portion;
A supply section for supplying gas to the hollow section and changing a contact state between the current collector and the first main surface;
A pressure difference detector that detects a pressure difference between the pressure in the hollow portion and the pressure in the first gas chamber;
A control unit for controlling the supply of gas by the supply unit based on the pressure difference;
A fuel cell comprising: A loss detection unit for detecting a DC voltage loss between the current collector and the fuel cell body;
2. The fuel cell according to claim 1, wherein the control unit controls gas supply based on the pressure difference and the DC voltage loss. The supply section is
A pressurizing pump for pressurizing the gas;
A first conduit for supplying the pressurized gas into the hollow portion;
A second conduit for supplying the pressurized gas to the first gas chamber;
A check valve disposed in the second pipe line and preventing a backflow of gas from the first gas chamber side to the supply unit,
The fuel cell according to claim 1 or 2, wherein The supply section is
A pressurizing pump for pressurizing the gas;
A first conduit for supplying the pressurized gas into the hollow portion;
A second conduit for supplying the pressurized gas to the first gas chamber;
A needle valve that is disposed in the second pipe and whose opening is adjustable;
The fuel cell according to claim 1 or 2, wherein The supply section is
A pressurizing pump for pressurizing the gas;
A first conduit for supplying the pressurized gas into the hollow portion;
A second conduit for supplying the pressurized gas to the first gas chamber;
A first valve disposed in the first conduit for regulating the supply of the pressurized gas into the hollow portion;
A second valve that is disposed in the first pipe and discharges gas from the hollow portion;
When the pressure difference is smaller than a predetermined value, the control unit opens the first valve,
When the pressure difference is larger than the predetermined value, the control unit opens the second valve;
The fuel cell according to claim 1 or 2, wherein The supply section is
A check valve disposed in the second pipe line to prevent a backflow of gas from the fuel cell body side to the supply part;
A second pressure difference detection unit for detecting a difference between a pressure upstream of the first valve and a pressure upstream of the check valve;
The fuel cell according to claim 5, wherein when the second pressure difference is smaller than the pressure difference, the control unit operates the pressurizing pump to pressurize the gas. The fuel cell according to any one of claims 1 to 6, wherein air is supplied to the first gas chamber. The fuel cell according to any one of claims 1 to 6, wherein fuel gas is supplied to the first gas chamber.

Images