JP2007227278A - Fuel cell device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a driving means driving a cell module and reduce the number of the diving means by separating the cell module on the most downstream side in a hydrogen gas passage in a fuel cell stack, driving only the cell module to conduct operation such as vibration or tilting movement, and quickly, surely eliminate flooding by simplifying the operation control of the driving means. <P>SOLUTION: A fuel cell device has a plurality of cell modules formed by stacking fuel cells interposing an electrolyte layer between a fuel electrode and an oxygen electrode through a separator on which a fuel gas passage is formed along the fuel electrode, the cell module is made conductive, and fuel gas passages are connected so as to continue them. The fuel cell device has a separation part containing at least one module on the most downstream side of the fuel cell passage and a body part containing other modules separated from the separation part, and the separation part has a driving means for driving the separation part when flooding is generated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell device.

  Conventionally, since fuel cells have high power generation efficiency and do not emit harmful substances, they have been put into practical use as power generators for industrial and household use, or as power sources for artificial satellites and spacecrafts. Development is progressing as a power source for vehicles such as buses, trucks, passenger carts, and luggage carts. The fuel cell may be of an alkaline aqueous solution type (AFC), phosphoric acid type (PAFC), molten carbonate type (MCFC), solid oxide type (SOFC), direct methanol (DMFC), or the like. Although good, a polymer electrolyte fuel cell (PEMFC) is common.

  In this case, the solid polymer electrolyte membrane is sandwiched between two gas diffusion electrodes and integrated to join. When one of the gas diffusion electrodes is used as a fuel electrode (anode electrode) and hydrogen gas as fuel is supplied to the surface thereof, hydrogen is decomposed into hydrogen ions (protons) and electrons, and the hydrogen ions are converted into a solid polymer electrolyte. Permeates the membrane. Further, when the other of the gas diffusion electrodes is an oxygen electrode (cathode electrode) and air as an oxidant is supplied to the surface, oxygen in the air is combined with the hydrogen ions and electrons to generate water. The An electromotive force is generated by such an electrochemical reaction.

  In the polymer electrolyte fuel cell, since it is necessary to maintain the polymer electrolyte membrane in a wet state, water is supplied to the oxygen electrode side. Moisture supplied to the oxygen electrode side moves as back diffusion water from the oxygen electrode side toward the fuel electrode side, and moves as proton-entrained water from the fuel electrode side toward the oxygen electrode side.

  By the way, it is known that when the amount of reverse diffusion water increases, flooding, which is a phenomenon in which the hydrogen gas flow path is blocked by moisture on the fuel electrode side, occurs and the performance of the fuel cell deteriorates. It has been. Therefore, a technique has been proposed in which when flooding occurs, the entire fuel cell stack is vibrated or inclined to discharge moisture from the flow path (see, for example, Patent Document 1).

In this case, the mount member interposed between the lower edge of the end plate disposed on both sides of the fuel cell stack and the support base that supports the fuel cell stack is used as a spring, and vibration imparting means and an inclination are provided to the fuel cell stack. When a driving means such as an attaching means is attached and the occurrence of flooding is detected, the driving means is operated to vibrate or tilt the entire fuel cell stack. It has also been proposed that the mount member itself is composed of drive means.
JP 2002-208423 A

  However, in the conventional fuel cell device, since the entire fuel cell stack is vibrated or tilted, the driving means for performing operations such as vibration and tilting needs to generate a strong force. And the driving means becomes large. In addition, when the hydrogen gas supply system in the fuel cell stack is a so-called series system, and the system sequentially circulates in a plurality of cell modules constituting the fuel cell stack, the hydrogen gas flow path has a meandering shape. Therefore, in order to move the moisture toward the outlet of the flow path, it is necessary to change the vibration direction and the inclination direction according to the movement state of the moisture in the flow path, and the operation control of the driving means is complicated. It will be difficult.

  The present invention solves the problems of the conventional fuel cell device, separates the cell module on the most downstream side of the hydrogen gas flow path in the fuel cell stack, and drives only the cell module to vibrate, tilt, etc. A fuel cell device capable of quickly and surely eliminating flooding even when the operation is performed so that the drive means for driving the cell module is reduced in size and number, and the operation control of the drive means is simplified. The purpose is to provide.

  Therefore, in the fuel cell device of the present invention, a fuel cell in which an electrolyte layer is sandwiched between a fuel electrode and an oxygen electrode is stacked with a separator having a fuel gas flow path formed along the fuel electrode. A fuel cell device having a plurality of cell modules, the cell modules being connected to each other such that the cell modules can conduct electricity and the fuel gas flow paths are continuous. A separation unit including one or more cell modules; and a main body unit including another cell module separated from the separation unit, the separation unit driving the separation unit when flooding occurs Is provided.

  In another fuel cell device of the present invention, the cell modules of the main body are connected to each other so that the fuel gas flow path is folded back for each cell module.

  In still another fuel cell device of the present invention, the separator is vibrated or tilted by the driving means when flooding occurs.

  In still another fuel cell device of the present invention, the separation unit further includes two end plates that sandwich the cell module from both sides, and the driving means drives one of the end plates.

  In still another fuel cell device of the present invention, the fuel cell device further includes a fuel gas flow channel connecting pipe that connects the fuel gas flow channel of the main body and the fuel gas flow channel of the separation unit, and a water discharge electromagnetic valve, A water discharge pipe connected to the fuel gas flow path connecting pipe, and the water discharge electromagnetic valve is opened when the driving means drives the separation section, and the fuel gas flow path of the main body section The water accumulated in the water is discharged from the water discharge pipe.

  According to the present invention, in a fuel cell device, a fuel cell in which an electrolyte layer is sandwiched between a fuel electrode and an oxygen electrode is laminated with a separator having a fuel gas flow path formed along the fuel electrode. A fuel cell device having a plurality of cell modules, the cell modules being connected to each other such that the cell modules can conduct electricity and the fuel gas flow paths are continuous. A separation unit including one or more cell modules; and a main body unit including another cell module separated from the separation unit, the separation unit driving the separation unit when flooding occurs Is provided.

  In this case, it is not necessary to drive the entire fuel cell stack, and only the separation unit needs to be driven, so that the drive means can be reduced in size and the energy consumption required for the operation of the drive means can be suppressed. Can do. Further, the water accumulated in the fuel gas flow path in the separation part can be quickly discharged, and the flooding can be eliminated in a short time, so that the operation time of the driving means can be shortened.

  In another fuel cell device, the cell modules of the main body are connected to each other so that the fuel gas flow path is folded back for each cell module.

  In this case, since it is not necessary to drive the main body, the mode of operation of the driving means can be simplified, the configuration of the driving means can be simplified, and the operation control of the driving means is also simplified. can do.

  In still another fuel cell device, the separation unit vibrates or tilts by the driving means when flooding occurs.

  In this case, moisture accumulated in the fuel gas flow path in the cell module of the separation unit can be quickly and reliably discharged.

  In still another fuel cell device, the separation unit further includes two end plates that sandwich the cell module from both sides, and the driving means drives one of the end plates.

  In this case, the number of drive means can be reduced, and the energy consumption required for the operation of the drive means can be suppressed.

  In yet another fuel cell device, the fuel gas further includes a fuel gas channel connecting pipe that connects the fuel gas channel of the main body and the fuel gas channel of the separation unit, and a water discharge electromagnetic valve. A water discharge pipe connected to the flow path connecting pipe, and the water discharge solenoid valve is opened when the drive means drives the separation part and collected in the fuel gas flow path of the main body part. Water is discharged from the water discharge pipe.

  In this case, since the occurrence frequency of flooding in the cell module of the separation unit can be suppressed, the total operation time of the driving means can be shortened, and the energy consumption required for the operation of the driving means can be suppressed. it can.

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

  FIG. 2 is a diagram showing the configuration of the fuel cell system according to the embodiment of the present invention.

  In the figure, reference numeral 11 denotes a fuel cell stack as a fuel cell (FC) device, which is used as a power source for vehicles such as passenger cars, buses, trucks, passenger carts and luggage carts. Here, the vehicle is equipped with a large number of auxiliary devices that consume electricity, such as lighting devices, radios, and power windows, which are used even when the vehicle is stopped. Since the output range is extremely wide, it is desirable to use the fuel cell stack 11 as a power source in combination with a capacitor unit 63 as a power storage means described later.

  The fuel cell stack 11 may be of an alkaline aqueous solution type, a phosphoric acid type, a molten carbonate type, a solid oxide type, a direct type methanol or the like, but is preferably a solid polymer type fuel cell. .

  More preferably, PEMFC (Proton Exchange Membrane Fuel Cell) type fuel cell or PEM (Proton Exchange Membrane) using hydrogen gas as fuel gas, that is, anode gas, and oxygen or air as oxidant, that is, cathode gas. ) Type fuel cell. Here, the PEM type fuel cell generally includes a cell as a fuel cell in which a catalyst, an electrode, and a separator are combined on both sides of a solid polymer electrolyte membrane as an electrolyte layer that transmits ions such as protons. It consists of a plurality of stacks connected in series.

  In the present embodiment, the fuel cell stack 11 has a plurality of cell modules 72 described later. The cell module 72 includes a unit cell (MEA) as a fuel cell, a flow path of hydrogen gas as an anode gas, which is electrically connected to each other and introduced into the unit cell. The separator for separating the air flow path as the cathode gas is set as one set, and a plurality of sets are stacked in the thickness direction. In the cell module 72, the unit cells and the separators are stacked in multiple layers so that the unit cells are arranged with a predetermined gap (gap) therebetween.

  In this case, the cell modules 72 are connected to each other so as to be conductive and so that the fuel gas flow path, that is, the hydrogen gas flow path is continuous. The fuel cell stack 11 includes a separation part 11b that is a part obtained by separating the cell module 72 on the most downstream side of the hydrogen gas flow path, and a main body part 11a that is separated from the separation part 11b and includes another cell module 72. It consists of. The cell modules 72 included in the separation unit 11b are one or more cell modules 72 on the most downstream side of the hydrogen gas flow path in the fuel cell stack 11, and the number thereof can be arbitrarily set. Here, for convenience of explanation, only the case where the cell module 72 included in the separation part 11b is a single cell module 72 on the most downstream side of the hydrogen gas flow path in the fuel cell stack 11 will be described.

  The unit cell includes an air electrode as an oxygen electrode provided on one side of the solid polymer electrolyte membrane as an electrolyte layer and a fuel electrode provided on the other side. The air electrode and the fuel electrode include an electrode diffusion layer made of a conductive material that permeates while diffusing the reaction gas, and a catalyst layer formed on the electrode diffusion layer and supported in contact with the solid polymer electrolyte membrane. Consists of. In addition, the current collector in contact with the electrode diffusion layer on the air electrode side of the unit cell and the air electrode side collector as a net-like current collector formed with a large number of openings through which a mixed flow of air and water is transmitted; And a current collector in contact with the electrode diffusion layer on the fuel electrode side of the unit cell, and a fuel electrode side collector as a net-like current collector having a large number of openings through which hydrogen gas permeates.

  In the unit cell, water moves. In this case, when fuel gas, that is, hydrogen gas as anode gas, is supplied into a fuel chamber as a hydrogen gas flow path formed on the fuel electrode side of the separator, hydrogen is decomposed into hydrogen ions and electrons, Permeates the solid polymer electrolyte membrane with proton-entrained water. Further, when the air electrode is used as a cathode electrode and an oxidant, that is, air as a cathode gas, is supplied into an oxygen chamber as an air flow path, oxygen in the air is combined with the hydrogen ions and electrons to form water. Is generated. Moisture permeates through the solid polymer electrolyte membrane as reverse diffusion water and moves into the fuel chamber. Here, the reverse diffusion water means that water generated in an oxygen chamber as an air channel diffuses into the solid polymer electrolyte membrane and permeates through the solid polymer electrolyte membrane in the direction opposite to the hydrogen ions. It has penetrated into the fuel chamber.

  In the figure, an apparatus for supplying hydrogen gas as a fuel gas to the fuel cell stack 11 and an apparatus for supplying air as an oxidant are shown. Although hydrogen gas, which is fuel taken out by reforming methanol, gasoline, or the like by a reformer (not shown), can be directly supplied to the fuel cell stack 11, it is stable and sufficient even during high-load operation of the vehicle. In order to be able to supply an amount of hydrogen gas, it is desirable to supply the hydrogen gas stored in the fuel storage means 21. Thereby, the hydrogen gas is always sufficiently supplied at a substantially constant pressure, so that the fuel cell stack 11 can follow the fluctuation of the load of the vehicle and supply a necessary current. . In this case, the output impedance of the fuel cell stack 11 is extremely low and can be approximated to zero.

  Hydrogen gas is stored in a container containing a hydrogen storage alloy, a container containing a hydrogen storage liquid such as decalin, a fuel storage means 21 such as a hydrogen gas cylinder, a first fuel supply line 22 as a fuel supply line, and The fuel is supplied to an inlet of a fuel gas flow path of the fuel cell stack 11 through a second fuel supply pipe 33 as a fuel supply pipe connected to the first fuel supply pipe 22. The first fuel supply line 22 includes a fuel storage means former opening / closing valve 23, a first pressure sensor 27a, a first fuel pressure adjustment valve 25a, a second pressure sensor 27b, a second fuel pressure adjustment valve 25b, a fuel. A supply electromagnetic valve 26 and a third pressure sensor 27c are provided. In this case, the fuel storage means 21 has a sufficiently large capacity and is capable of always supplying sufficiently high pressure hydrogen gas.

  Then, the hydrogen gas discharged as an unreacted component from the outlet of the fuel gas flow path of the fuel cell stack 11 is discharged out of the fuel cell stack 11 through the fuel discharge pipe 31. A water recovery drain tank 35 as a recovery container is disposed in the fuel discharge line 31. The water recovery drain tank 35 is provided with a level gauge (water level gauge) 35a. The water recovery drain tank 35 is connected with a fuel discharge line 30 for discharging hydrogen gas separated from water, and the fuel discharge line 30 is provided with a suction circulation pump 36 as a pump. . A hydrogen circulation electromagnetic valve 34 is disposed in the fuel discharge line 30. Further, the end of the fuel discharge line 30 opposite to the water recovery drain tank 35 is connected to the second fuel supply line 33. Thereby, the hydrogen gas discharged out of the fuel cell stack 11 can be recovered, supplied to the fuel gas flow path of the fuel cell stack 11 and reused.

  Further, a startup fuel discharge line 38 is connected to the water recovery drain tank 35, and a hydrogen startup exhaust solenoid valve 37 is disposed in the startup fuel discharge line 38, so that when the fuel cell stack 11 is started up. The hydrogen gas discharged from the fuel gas channel can be discharged into the atmosphere. The outlet end of the starting fuel discharge pipe 38 is connected to the exhaust manifold 13. In addition, a hydrogen combustor may be provided in the startup fuel discharge line 38 as necessary. The hydrogen gas discharged by the hydrogen combustor can be combusted to form water, and then discharged into the atmosphere.

  Here, the first fuel pressure regulating valve 25a and the second fuel pressure regulating valve 25b are those of a butterfly valve, a regulator valve, a diaphragm type valve, a mass flow controller, a sequence valve, etc., but the first fuel pressure regulating valve Any type of hydrogen gas may be used as long as the pressure of the hydrogen gas flowing out from the outlets of 25a and the second fuel pressure regulating valve 25b can be adjusted to a preset pressure. The pressure adjustment may be performed manually, but is preferably performed by an actuator including an electric motor, a pulse motor, an electromagnet, or the like.

  The fuel supply solenoid valve 26, the hydrogen circulation solenoid valve 34, and the hydrogen activation exhaust solenoid valve 37 are so-called on-off types, and are operated by an actuator including an electric motor, a pulse motor, an electromagnet, and the like. The fuel storage means original opening / closing valve 23 is operated manually or automatically using an electromagnetic valve. Further, the suction circulation pump 36 may be of any type as long as it can forcibly discharge the reverse diffusion water together with the hydrogen gas and can bring the inside of the fuel gas passage into a negative pressure state. Good.

  On the other hand, the air as the oxidant passes through the air filter 53 and is sucked into the air supply fan 51 as the oxidant supply source, and from the air supply fan 51 through the air supply line 52 and the intake manifold 12. The fuel cell stack 11 is supplied to an oxygen chamber, that is, an air flow path. In this case, the pressure of the supplied air is a normal pressure of about atmospheric pressure. The air supply fan 51 may be of any type as long as it can suck and discharge air. The air filter 53 may be of any type as long as it can remove dust, impurities, etc. contained in the air. Note that oxygen can be used as the oxidizing agent instead of air. And the air discharged | emitted from an air flow path is discharged | emitted in air | atmosphere through the exhaust manifold 13, the condenser 14, the exit side exhaust manifold 54, and the exhaust port 55 as a manifold. The exhaust manifold 13 is provided with a stack exhaust temperature detector 56 for detecting the temperature of air immediately after being discharged from the fuel cell stack 11, and the outlet side exhaust manifold 54 is immediately after being discharged from the condenser 14. A condenser exhaust temperature detector 57 for detecting the temperature of the air is provided.

  The air supply pipe 52 is supplied with water sprayed into the air supplied to the air flow path, and water for maintaining the air electrode as the oxygen electrode of the fuel cell stack 11 in a wet state. A supply nozzle 47 is provided. The air electrode and the fuel electrode can be cooled by the sprayed water. Further, the condenser 14 disposed at the end of the exhaust manifold 13 is for condensing and removing moisture in the air discharged from the fuel cell stack 11, and is condensed by the condenser 14. The water thus collected is collected in the water tank 43 through the condensed water discharge pipe 41. The condensed water discharge pipe 41 is provided with a drain pump 42, and the water tank 43 is provided with a level gauge 43a.

  The water in the water tank 43 is supplied to the water supply nozzle 47 through the water supply pipe 46. A water supply pump 44 and a water filter 45 are disposed in the water supply pipe 46. Here, the drainage pump 42 and the water supply pump 44 may be of any type as long as they can suck and discharge water. The water filter 45 may be of any type as long as it can remove dust, impurities, and the like contained in water. The condensed water discharge pipe 41, the drainage pump 42, the water tank 43, the water supply pump 44, the water filter 45, and the water supply pipe 46 function as a water circulation system.

  Furthermore, an inverter device 61 as a drive control device as a load and a capacitor unit 63 as a power storage unit are connected in parallel to an electric terminal (not shown) of the fuel cell stack 11. The capacitor unit 63 includes a capacitor (capacitor) such as an electric double layer capacitor. In addition, the said electrical storage means does not necessarily need to be a capacitor, and secondary batteries, such as a lead storage battery, a nickel cadmium battery, a nickel hydride battery, a lithium ion battery, and a sodium sulfur battery, may be what is called a battery (storage battery). Any form may be used as long as it has a function of electrically storing and discharging energy, such as a flywheel, a superconducting coil, and a pressure accumulator. Furthermore, any of these may be used alone, or a plurality of them may be used in combination.

  Further, the inverter device 61 converts a direct current from the fuel cell stack 11 or the capacitor unit 63 into an alternating current and supplies the alternating current to an unillustrated alternating current motor that is a drive source for rotating the wheels of the vehicle. Here, in the fuel cell system, the fuel cell stack 11 or the capacitor unit 63 is connected in parallel to supply current to the inverter device 61. For example, when the vehicle is stopped, the fuel cell stack When the stack 11 is stopped or when the current from the fuel cell stack 11 does not satisfy the required current during high load operation such as on a slope, the current is automatically supplied from the capacitor unit 63 to the inverter device 61. The

  Reference numeral 62 denotes an IGBT unit including an IGBT (insulated gate bipolar transistor) which is a high-speed switching element as a charging switching element, and is a control circuit that controls charging of the capacitor unit 63.

  When the AC motor functions as a power generator during vehicle deceleration operation and generates a so-called regenerative current, the regenerative current is supplied to the capacitor unit 63 during the vehicle deceleration operation, and the capacitor unit 63 Recharged. Further, even when the regenerative current is not supplied to the capacitor unit 63, when the capacitor unit 63 is discharged and the terminal voltage decreases, the current generated by the fuel cell stack 11 is automatically supplied to the capacitor unit 63. Supplied.

  As described above, in the fuel cell system, when the capacitor unit 63 is constantly charged and the current from the fuel cell stack 11 alone does not satisfy the required current, the current is supplied from the capacitor unit 63 to the inverter device 61. Since the vehicle is automatically supplied, the vehicle can travel stably in various travel modes.

  In the present embodiment, the hydrogen gas flow path in the main body part 11 a of the fuel cell stack 11 and the hydrogen gas flow path in the separation part 11 b are connected by a fuel gas flow path connecting pipe 75. Further, one end of a water discharge pipe 76 for discharging water that has permeated into the fuel chamber as reverse diffusion water in each unit cell of the main body portion 11a is connected to the fuel gas flow path connecting pipe 75. The other end of the moisture discharge pipe 76 is connected to the fuel discharge pipe 31. The water discharge pipe 76 is provided with a water discharge electromagnetic valve 77, which opens and closes the water discharge pipe 76 as necessary, so that the water accumulated in the hydrogen gas flow path in the main body 11a can be removed from the fuel gas flow path. The fuel can be discharged through the connecting pipe 75 and the water discharge pipe 76, and can be directly introduced into the fuel discharge pipe 31 by bypassing the separation portion 11b.

  In the present embodiment, the fuel cell system has an FC control ECU (Electronic Control Unit) (not shown) as a control device. The control device includes arithmetic means such as a CPU and MPU, storage means such as a magnetic disk and a semiconductor memory, an input / output interface, and the like, and is supplied from various sensors to the fuel gas flow path and the air flow path of the fuel cell stack The air supply fan 51, the first fuel pressure adjustment valve 25a, the second fuel pressure adjustment valve 25b, the fuel supply electromagnetic valve 26, hydrogen are detected by detecting the flow rate, temperature, output voltage, etc. of hydrogen, oxygen, air, etc. The operations of the circulation electromagnetic valve 34, the suction circulation pump 36, the drainage pump 42, the water supply pump 44, the water discharge electromagnetic valve 77, and the like are controlled. Further, the FC control ECU cooperates with other sensors provided in the vehicle and an EV (Electric Vehicle) control ECU (not shown) as a vehicle control means to supply fuel and oxidant to the fuel cell stack 11. Centrally control the operation of all equipment supplied.

  Next, the configuration of the fuel cell stack 11 will be described in detail.

  FIG. 1 is a diagram showing a configuration of a fuel cell stack according to an embodiment of the present invention. 1A is a top view of the fuel cell stack, and FIG. 1B is a side view of the fuel cell stack.

  In the example shown in FIG. 1, the fuel cell stack 11 has a total of ten cell modules 72, the main body portion 11 a includes nine cell modules 72, and the separation portion 11 b is the uppermost part of the hydrogen gas flow path in the fuel cell stack 11. One cell module 72 on the downstream side is included. As described above, the number of cell modules 72 included in the separation unit 11b can be arbitrarily set. For example, the main body unit 11a includes eight or less cell modules 72, and the separation unit 11b is included in the fuel cell stack 11. It is also possible to include two or more continuous cell modules 72 on the most downstream side of the hydrogen gas flow path. Furthermore, the number of cell modules 72 that the fuel cell stack 11 has as a whole is not limited to ten, and can be arbitrarily changed. For convenience of explanation, as shown in FIG. 1, the main body portion 11 a includes nine cell modules 72, and the separation portion 11 b is one cell on the most downstream side of the hydrogen gas flow path in the fuel cell stack 11. Only the case including the module 72 will be described.

  Here, the main body 11a has an end plate 71a and a current collecting plate 78a disposed on the inlet side (left side in the figure) and outlet side (right side in the figure) of hydrogen gas. And the cell module 72 in the main-body part 11a is the state pinched | interposed by the end plate 71a via the current collection board 78a from the entrance side and exit side of hydrogen gas. The hydrogen gas inlet side and outlet side end plates 71a are connected to each other in a state in which a force for fastening the cell module 72 is applied by a fastening shaft (not shown). The cell module 72 closest to the hydrogen gas inlet side is electrically connected to the current collector plate 78a on the hydrogen gas inlet side, and the cell module 72 closest to the hydrogen gas outlet side is collected on the hydrogen gas outlet side. It is electrically connected to the electric plate 78a. Further, the cell modules 72 have good electrical conductivity. When it is necessary to electrically insulate the end plate 71a and the current collector plate 78a, an insulating plate can be interposed between the end plate 71a and the current collector plate 78a.

  Similarly, the separation portion 11b includes an end plate 71b and a current collector plate 78b disposed on the inlet side (left side in the figure) and the outlet side (right side in the figure) of hydrogen gas. The cell module 72 in the separation part 11b is sandwiched by the end plate 71b from the hydrogen gas inlet side and the outlet side via the current collector plate 78b. The hydrogen gas inlet side and outlet side end plates 71b are connected to each other in a state in which a force for fastening the cell module 72 is applied by a fastening shaft (not shown). The cell module 72 is electrically connected to a collector plate 78b on the inlet side and outlet side of the hydrogen gas, and the collector plate 78b on the inlet side of the hydrogen gas is further connected to the main body 11a by a conductive wire (not shown). Is electrically connected to the current collector plate 78a on the hydrogen gas outlet side. When it is necessary to electrically insulate the end plate 71b and the current collector plate 78b, an insulating plate can be interposed between the end plate 71b and the current collector plate 78b.

  A fuel inlet pipe 73 is connected to the end plate 71a on the inlet side of the hydrogen gas in the main body 11a. Since the end of the fuel inlet pipe 73 opposite to the end plate 71 a is connected to the end of the second fuel supply pipe 33, the hydrogen gas supplied through the second fuel supply pipe 33 is The fuel is introduced into the main body portion 11a through the fuel inlet pipe 73.

  A fuel outlet pipe 74 is connected to the end plate 71b on the outlet side of the hydrogen gas in the separation part 11b. Since the end of the fuel outlet pipe 74 opposite to the end plate 71 b is connected to the end of the fuel discharge pipe 31, the hydrogen gas discharged from the separation section 11 b is fueled via the fuel outlet pipe 74. It flows into the discharge pipe 31 and is discharged out of the fuel cell stack 11.

  Further, a fuel gas flow path connecting pipe 75 is connected to the end plate 71a on the hydrogen gas outlet side in the main body 11a and the end plate 71b on the hydrogen gas inlet side in the separation part 11b. The hydrogen gas discharged from the main body portion 11a is introduced into the separation portion 11b via the fuel gas flow channel connecting pipe 75. In addition, a moisture discharge pipe 76 is connected to the fuel gas flow path connecting pipe 75. In a normal state, the moisture discharge electromagnetic valve 77 disposed in the moisture discharge pipe 76 is closed. The hydrogen gas discharged from the main body 11 a is not discharged out of the fuel cell stack 11 through the moisture discharge pipe 76.

  In the example shown in FIG. 1, the hydrogen gas supply system in the fuel cell stack 11 is a so-called series system, and the system sequentially distributes in each cell module 72. That is, the cell modules 72 of the main body 11 a are connected to each other so that the hydrogen gas flow path is folded back for each cell module 72. Therefore, the hydrogen gas flow path has a serpentine shape as indicated by an arrow in FIG. The hydrogen gas supply system in the main body 11a may be a so-called parallel system. In the case of the parallel system, hydrogen gas flows in parallel in each cell module 72 in the main body portion 11a in the same direction (from top to bottom in FIG. 1A). Here, for convenience of explanation, as shown in FIG. 1A, only the case where the hydrogen gas supply system is a series system will be described.

  In the present embodiment, the main body 11a is a vehicle frame or the like shown through a mounting member 81 as a fixing means attached to the lower end of an end plate 71a disposed on the inlet side and outlet side of the hydrogen gas. It is fixedly attached to a support member that is not. The mount member 81 is a spacer member made of, for example, metal or resin, but may be any type of member.

  The separation part 11b is attached to the support member via drive means 82 attached to the lower end of an end plate 71b disposed on the inlet side and the outlet side of the hydrogen gas. The driving means 82 is a device for driving the separating portion 11b to perform operations such as vibration and tilting. For example, a hydraulic cylinder, a pneumatic cylinder, an electric motor, a linear motor, a piezoelectric element, a shape memory alloy, etc. For example, the actuator performs an operation such as a reciprocating motion or an eccentric rotational motion depending on the driving source. However, any type of device may be used. The operation of the driving means 82 is controlled by the FC control ECU.

  When the separation unit 11b is vibrated, the driving means 82 attached to the lower end of the end plate 71b disposed on the inlet side and the outlet side of the hydrogen gas, for example, periodically moves the end plate 71b up and down or left and right. Reciprocate. In this case, the period and amplitude of vibration of the separation part 11b can be controlled by controlling the period and stroke of the reciprocating motion of the driving means 82. The operation of the driving means 82 attached to the lower end of the end plate 71b disposed on the hydrogen gas inlet side and the driving means 82 attached to the lower end of the end plate 71b disposed on the hydrogen gas outlet side. The operation may be synchronized or may not be synchronized. For example, the phase of operation of the drive means 82 attached to the lower end of the end plate 71b disposed on the hydrogen gas inlet side and the drive attached to the lower end of the end plate 71b disposed on the hydrogen gas outlet side. The phase of the operation of the means 82 can be shifted by 180 degrees. In this way, by vibrating the separation part 11b, the water accumulated in the hydrogen gas flow path in the cell module 72 of the separation part 11b can be discharged from the fuel outlet pipe 74.

  When tilting the separation part 11b, the driving means 82 attached to the lower end of the end plate 71b disposed on the inlet side and the outlet side of the hydrogen gas moves the end plate 71b upward or downward, for example. In this case, by controlling the moving direction and stroke of the driving unit 82, the direction and angle of inclination of the separating portion 11b can be controlled. The driving direction of the driving means 82 attached to the lower end of the end plate 71b disposed on the hydrogen gas inlet side and the driving means attached to the lower end of the end plate 71b disposed on the hydrogen gas outlet side. The driving directions 82 are preferably opposite to each other. For example, by moving the end plate 71b disposed on the hydrogen gas inlet side upward and moving the end plate 71b disposed on the hydrogen gas outlet side downward, the hydrogen gas outlet side is lowered. The separating portion 11b can be tilted. By tilting the separation part 11b in this way, moisture accumulated in the hydrogen gas flow path in the cell module 72 of the separation part 11b can be discharged from the fuel outlet pipe 74.

  The drive means 82 may be attached only to either the end plate 71b disposed on the hydrogen gas inlet side or the end plate 71b disposed on the hydrogen gas outlet side. In this case, the lower end of the other end plate 71b is fixed to the support member via the same fixing means as the mount member 81, but the fixing means rotates the support member of the other end plate 71b. Tolerable to some extent. Thus, when the driving means 82 attached to the lower end of one end plate 71b drives the separating portion 11b, the separating portion 11b performs operations such as vibration and tilting around the lower end of the other end plate 71b. It becomes.

  In addition, a voltmeter (not shown) is attached to the fuel cell stack 11 in order to measure an electromotive force of a unit cell, that is, a cell voltage. As described above, in the unit cell, the water moves as reverse diffusion water into the fuel chamber of the fuel electrode side collector. When viewed finely, the distribution of moisture in the fuel chamber is not necessarily uniform, and the amount of moisture, the flow velocity, and the like vary locally. For this reason, a large amount of moisture is concentrated locally, and flooding that inhibits the flow of hydrogen gas in the fuel chamber may occur. When flooding occurs in the fuel chamber, the fuel electrode is covered with moisture and cannot come into contact with hydrogen gas, and the cell voltage of the unit cell decreases. Therefore, by measuring the cell voltage, it is possible to detect that flooding has occurred in the unit cell.

  In addition, if it is going to measure the cell voltage of all the unit cells, the number of voltmeters will increase and cost will become high. Therefore, it is desirable to appropriately select a unit cell located at a place where flooding is likely to occur, and detect the occurrence of flooding in the fuel cell stack 11 based on the cell voltage of the selected unit cell. By the way, the moisture in the fuel chamber moves to the downstream side along with the flow of the hydrogen gas, but the flow rate of the hydrogen gas in the fuel cell stack 11 is high in the upstream and slows down toward the downstream. Moisture easily accumulates in the road, and the probability of occurrence of flooding increases. Therefore, in the present embodiment, the cell voltage of the unit cell included in the cell module 72 on the most downstream side of the hydrogen gas flow path in the fuel cell stack 11, that is, the cell module 72 of the separation unit 11b is detected. ing. If necessary, the cell voltage of the unit cell included in the cell module 72 of the main body 11a can be detected.

  Next, the operation of the fuel cell system having the above configuration will be described. First, the operation in steady operation will be described.

  During steady operation in the fuel cell system of the present embodiment, after adjusting the pressure of hydrogen gas flowing out from the outlets of the first fuel pressure adjustment valve 25a and the second fuel pressure adjustment valve 25b to a predetermined constant pressure, The first fuel pressure adjustment valve 25a and the second fuel pressure adjustment valve 25b are not adjusted during operation of the fuel cell system, and are maintained as they are. The air supply fan 51 operates so as to be supplied with air set in advance according to the output current of the fuel cell. In this case, the amount of air supplied is an amount sufficiently larger than the amount of air necessary for the output of the fuel cell stack 11 to be maximized. Further, in the present embodiment, the pressure of the air supplied to the unit cell of the fuel cell stack 11 is a normal pressure of about atmospheric pressure and does not need to be particularly pressurized. Therefore, the air supply fan 51, the air supply pipe 52, the intake manifold 12, the exhaust manifold 13, the condenser 14, the outlet side exhaust manifold 54, and the like do not need to have pressure resistance, so that the configuration can be simplified. .

  When the fuel cell stack 11 starts operation, reverse diffusion water is generated in each unit cell constituting the fuel cell stack 11, and the reverse diffusion water permeates the solid polymer electrolyte membrane and enters the fuel gas flow path. Until the fuel electrode side of the solid polymer electrolyte membrane is humidified. As a result, the fuel electrode side of the solid polymer electrolyte membrane becomes wet, and hydrogen ions generated from hydrogen by the electrochemical reaction can move smoothly in the solid polymer electrolyte membrane.

  Further, the hydrogen gas as an unreacted component that is supplied to the fuel gas flow path and surplus is mixed with the back-diffused water that has permeated into the fuel gas flow path and becomes surplus, and a gas-liquid mixture Become. The hydrogen gas that has become the gas-liquid mixture is sucked by the suction circulation pump 36 and discharged to the outside of the fuel cell stack 11 through the fuel discharge pipe 31 connected to the fuel cell stack 11. The gas-liquid mixture passes through the fuel discharge pipe 31 and is introduced into the water recovery drain tank 35. Then, by staying in the water recovery drain tank 35 having a relatively wide space, heavy moisture falls downward due to gravity, and reverse diffusion water is separated from hydrogen gas. The hydrogen gas in a state where the reverse diffusion water is separated and dried is discharged out of the water recovery drain tank 35 from the fuel discharge line 30.

  In steady operation, the hydrogen gas discharged from the fuel discharge line 30 passes through the open hydrogen circulation electromagnetic valve 34, is introduced into the second fuel supply line 33, and again. Then, it is supplied to the fuel gas flow path of the fuel cell stack 11 and reused.

  Further, air as an oxidant sent from the intake manifold 12 passes through an oxygen chamber as an air flow path in the fuel cell stack 11 and is discharged toward the exhaust manifold 13. By the way, a water supply nozzle 47 is disposed in the air supply pipe 52, and water is sprayed. The water sprayed from the water supply nozzle 47 enters a large number of oxygen chambers by gravity and air flow. Since the air electrode is kept in a wet state, the solid polymer electrolyte membrane sandwiched between the air electrode and the fuel electrode functions well. In addition, in an electrochemical reaction in which hydrogen, which is a fuel, and oxygen, which is an oxidant, combine to generate water, reaction heat is generated, which is absorbed by the sprayed water. That is, the sprayed water also performs a cooling function.

  Here, the sprayed water is in a liquid state, that is, in a liquid phase, and absorbs heat of reaction to vaporize. Therefore, the cooling efficiency is extremely high because the oxygen electrode and the like in the oxygen chamber are cooled by the latent heat of vaporization. Further, since the liquid phase water is merely sprayed into the atmospheric pressure air, the water supply nozzle 47 may be a normal one and does not need to have a special configuration. Since the sprayed water is discharged from the oxygen chamber together with air, the air discharged from the fuel cell stack 11 into the exhaust manifold 13 contains moisture.

  Then, the air discharged into the exhaust manifold 13 is introduced into the condenser 14. Here, although the air contains water, the water cooled and condensed while passing through the condenser 14 is separated, and the air passes through the outlet side exhaust manifold 54 and the exhaust port 55 from the condenser 14 to the atmosphere. Discharged inside. The water separated by the condenser 14 is collected in the water tank 43 through the condensed water discharge pipe 41.

  Next, the operation when flooding occurs will be described.

  First, the FC control ECU, when the value of the cell voltage detected by the voltmeter that detects the cell voltage of the unit cell included in the cell module 72 of the separation unit 11b is less than or equal to a preset threshold value. Then, it is determined that flooding has occurred in the cell module 72 of the separation unit 11b. Note that it may be determined that flooding has occurred in the cell module 72 of the separation unit 11b when the difference from the preset standard value of the cell voltage becomes a predetermined value or more.

  When the FC control ECU determines that flooding has occurred in the cell module 72 of the separation unit 11b, the FC control ECU causes the drive unit 82 to drive the separation unit 11b and causes the separation unit 11b to perform operations such as vibration and tilting. As a result, the water accumulated in the hydrogen gas flow path in the cell module 72 of the separation unit 11b is discharged from the fuel outlet pipe 74 to the outside of the fuel cell stack 11 through the fuel discharge pipe 31, and the water recovery drain tank 35 Introduced in.

  In this case, the FC control ECU monitors the cell voltage of the unit cell included in the cell module 72 of the separation unit 11b, and until the value of the cell voltage returns to the threshold value or more, the drive unit 82 of the separation unit 11b. Continue driving. When the value of the cell voltage is equal to or greater than the threshold value, the FC control ECU determines that the flooding in the cell module 72 of the separation unit 11b has been eliminated, and stops driving of the separation unit 11b by the driving unit 82, Operations such as vibration and tilting of the separation unit 11b are stopped.

  By the way, when flooding occurs in the cell module 72 of the separation part 11b, it can be considered that the amount of water accumulated in the hydrogen gas flow path in the cell module 72 of the main body part 11a is also increased. Therefore, the generation of subsequent flooding in the cell module 72 of the separation unit 11b is performed by discharging the water accumulated in the hydrogen gas flow path in the cell module 72 of the main body unit 11a at the same timing as when the driving unit 82 is operated. Can be suppressed.

  Therefore, the FC control ECU is configured to open the moisture discharge electromagnetic valve 77 disposed in the moisture discharge pipe 76 at the same time when the driving means 82 is operated. As a result, the water accumulated in the hydrogen gas flow path in the cell module 72 of the main body portion 11a is discharged from the fuel gas flow path connecting pipe 75, and passes through the fuel discharge pipe 31 from the water discharge pipe 76 to the fuel cell stack. 11 is discharged to the outside and introduced into the water recovery drain tank 35. The FC control ECU closes the water discharge electromagnetic valve 77 simultaneously with stopping the driving means 82. Thereby, in steady operation, hydrogen gas does not bypass the cell module 72 of the separation unit 11 b and is discharged from the fuel cell stack 11 through the moisture discharge pipe 76.

  Thus, in the present embodiment, in order to separate the cell module 72 on the most downstream side of the hydrogen gas flow path in the fuel cell stack 11, the fuel cell stack 11 is separated into the main body portion 11a and the separation portion 11b. The flooding is eliminated by causing only the separation part 11b to perform operations such as vibration and tilting. Therefore, it is not necessary to cause the entire fuel cell stack 11 to perform the operation, and only the separation unit 11b needs to perform the operation. Therefore, the driving unit 82 can be reduced in size and the operation of the driving unit 82 can be performed. It is possible to suppress the energy consumption required for the operation.

  Further, the water accumulated in the hydrogen gas flow path in the separation part 11b can be quickly discharged, and the flooding can be eliminated in a short time, so that the operation time of the drive means 82 can be shortened. Therefore, the energy consumption required for the operation of the drive means 82 can be further suppressed.

  Furthermore, since the hydrogen gas flow path in the cell module 72 of the separation unit 11b is simple without meandering, the mode of operation for moving the moisture accumulated in the hydrogen gas flow path toward the fuel outlet pipe 74 is simple. It becomes. Therefore, even if the number of driving means 82 is reduced and the driving means 82 is attached only to one of the end plates 71b, the water accumulated in the hydrogen gas flow path is moved toward the fuel outlet pipe 74, It can be discharged quickly and reliably. Further, since the mode of operation of the driving means 82 is simplified, the configuration of the driving means 82 can be simplified, and the operation control of the driving means 82 by the FC control ECU can be simplified.

  Even if the fuel cell stack 11 is separated into the main body portion 11a and the separation portion 11b, the weight of the fuel cell stack 11 does not increase. This is because the end plate 71a and the end plate 71b made of thinner plate members can be used as end plates that occupy a large proportion of the weight of the fuel cell stack 11, so that the total weight of the end plates is determined by the total weight of the end plates. This is because there is almost no change whether or not 11 is separated into the main body portion 11a and the separation portion 11b.

  Furthermore, a water discharge pipe 76 provided with a water discharge electromagnetic valve 77 is connected to a fuel gas flow path connecting pipe 75 that connects the hydrogen gas flow paths in the main body 11a and the separation section 11b, and the main body 11a The water accumulated in the hydrogen gas flow path in the cell module 72 can be discharged from the fuel gas flow path connecting pipe 75. Therefore, the occurrence frequency of flooding in the cell module 72 of the separation unit 11b can be suppressed. Thereby, the total operating time of the driving means 82 can be shortened, and the energy consumption required for the operation of the driving means 82 can be further suppressed. If necessary, the water discharge pipe 76 provided with the water discharge electromagnetic valve 77 can be omitted.

  The present invention is not limited to the above-described embodiment, and various modifications can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention.

It is a figure which shows the structure of the fuel cell stack in embodiment of this invention. It is a figure which shows the structure of the fuel cell system in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Fuel cell stack 11a Main body part 11b Separation part 71b End plate 72 Cell module 75 Fuel gas flow path connection pipe 76 Moisture discharge pipe 77 Moisture discharge electromagnetic valve 82 Driving means

Claims (5)

A fuel cell in which an electrolyte layer is sandwiched between a fuel electrode and an oxygen electrode has a plurality of cell modules stacked with a separator having a fuel gas flow path formed along the fuel electrode, and the cell module is electrically conductive. A fuel cell device that is connected to each other so that the fuel gas flow paths are continuous,
A separation part including one or more cell modules on the most downstream side of the fuel gas flow path, and a main body part including another cell module separated from the separation part,
The fuel cell device according to claim 1, wherein the separation unit includes a driving unit that drives the separation unit when flooding occurs.   2. The fuel cell device according to claim 1, wherein the cell modules of the main body are connected to each other so that the fuel gas flow path is folded back for each cell module.   2. The fuel cell device according to claim 1, wherein the separation unit vibrates or tilts by the driving unit when flooding occurs. The separation part includes two end plates that sandwich the cell module from both sides,
The fuel cell device according to claim 3, wherein the driving unit drives one of the end plates. A fuel gas channel connecting pipe that connects the fuel gas channel of the main body and the fuel gas channel of the separation unit;
A water discharge pipe provided with a water discharge solenoid valve and connected to the fuel gas flow path connecting pipe;
2. The fuel according to claim 1, wherein the water discharge solenoid valve is opened when the driving unit drives the separation unit, and discharges water accumulated in the fuel gas flow path of the main body from the water discharge pipe. Battery device.

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