JP2007299565A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to make catalyst reaction sufficiently in a fuel electrode, and to increase power output. <P>SOLUTION: The fuel cell comprises a plurality of cells having an electrolyte membrane, an air electrode installed on one side of the electrolyte membrane, and a fuel electrode installed on the other side of the electrolyte membrane, and separators which are arranged between each cells and shuts off fuel gas and air supplied respectively to adjoining cells, and form an air supply passage between the air electrode and a fuel supply passage between the fuel electrode. The separator is provided with a temperature change relaxation part which alleviates temperature change of the cells when the load applied on the fuel cell changes. It can make the temperature constant when the fuel cell has changed from operation state of high load to the operation state of low load. Formation of waterdrop by condensation of steam on the fuel electrode side can be eliminated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell.

  Conventionally, in a vehicle equipped with a fuel cell (hereinafter referred to as “vehicle equipped with a fuel cell”), a current generated by the stacked fuel cell is supplied to a drive motor, and torque is generated by driving the drive motor. It is trying to generate.

  For this purpose, an on-vehicle fuel cell system is disposed in the vehicle equipped with the fuel cell, and the on-vehicle fuel cell system is supplied with a fuel tank in which liquid hydrogen is stored, hydrogen gas is supplied from the fuel tank, and air is supplied. A fuel cell stack constituting the stacked fuel cell, a condenser for condensing the vapor in the gas discharged from the fuel cell stack, and separating the vapor into water and gas.

  In the fuel cell stack, a module is accommodated in a stack case, and the module is composed of an assembly configured by electrically connecting a plurality of cells constituting the elements of the fuel cell to each other in series. . Each cell has a membrane electrode assembly (MEA), which is a membrane-electrode assembly formed by disposing an anode and a fuel electrode including a reaction layer and a diffusion layer with an electrolyte membrane interposed therebetween, And a separator for separating the membrane electrode assemblies and forming an air supply path facing the air electrode and a fuel supply path facing the fuel electrode.

The air electrode functions as a cathode, the fuel electrode functions as an anode, air is supplied to the air electrode, hydrogen gas is supplied to the fuel electrode, and a load device is connected to the air electrode and the fuel electrode via the separator. Catalytic reaction takes place at the electrode, hydrogen is decomposed into hydrogen ions (protons) and electrons, and the hydrogen ions move to the air electrode side in the electrolyte membrane containing moisture in the form of protons (H ⁺ ). Combines with oxygen to produce water. Further, electrons generated at the fuel electrode move to the air electrode side via the load device, and a current is generated accordingly. That is, a current is generated by reacting hydrogen and oxygen, and the current can be supplied to the load device via the separator.

  However, for example, when the driver depresses the accelerator pedal and accelerates the fuel cell vehicle, or travels on an uphill road, the driver decelerates the fuel cell vehicle by decelerating or decelerating the fuel cell vehicle. When the vehicle changes to a low-load driving state such as traveling on a slope, the fuel cell changes from a high-load operation state to a low-load operation state, but with this, water vapor condenses on the surface of the separator on the fuel supply path side. Water droplets may adhere. In particular, in a fuel cell stack in which the output is increased and the stacking density is increased, the cell is thinned and a metal separator is used as a separator. In this case, since the heat capacity of the cell is reduced, it is temporarily attached. The water drops that have been removed will not be eliminated.

  As a result, hydrogen gas does not flow smoothly at the fuel electrode, and the catalytic reaction is not sufficiently performed. As a result, the output is reduced.

Therefore, a fuel cell is provided in which a heater is provided in the separator and the separator is heated by the heater so as to exclude water droplets (see, for example, Patent Document 1).
JP 2004-220946 A

  However, in the conventional fuel cell, since it is necessary to energize the heater, power is consumed. Therefore, the output of the fuel cell cannot be increased sufficiently.

  An object of the present invention is to solve the problems of the conventional fuel cell and to provide a fuel cell in which a catalytic reaction is sufficiently performed at the fuel electrode and the output can be increased.

  Therefore, in the fuel cell of the present invention, a plurality of cells including an electrolyte membrane, an air electrode disposed on one side of the electrolyte membrane, and a fuel electrode disposed on the other side of the electrolyte membrane; The fuel gas and air that are disposed between the cells and are respectively supplied to adjacent cells are shut off, and an air supply path is formed between the air electrodes and a fuel supply path is formed between the fuel electrodes. And a separator.

  And this separator is provided with the temperature change mitigation part which relieve | moderates the temperature change of a cell when the load added to the said fuel cell changes.

  In another fuel cell of the present invention, the temperature change relaxation portion is a phase change element embedded in a separator.

  In still another fuel cell of the present invention, the temperature change relaxation portion is a phase change element applied to a separator.

  According to the present invention, in a fuel cell, a plurality of cells including an electrolyte membrane, an air electrode disposed on one side of the electrolyte membrane, and a fuel electrode disposed on the other side of the electrolyte membrane; The fuel gas and air that are disposed between the cells and are respectively supplied to adjacent cells are shut off, and an air supply path is formed between the air electrodes and a fuel supply path is formed between the fuel electrodes. And a separator.

  And this separator is provided with the temperature change mitigation part which relieve | moderates the temperature change of a cell when the load added to the said fuel cell changes.

  In this case, since the separator includes a temperature change mitigation unit that moderates the temperature change of the cell when the load applied to the fuel cell changes, when the fuel cell changes from a high load operation state to a low load operation state In addition, the temperature can be kept constant.

  Accordingly, since water vapor is not condensed and water droplets are not formed on the fuel electrode side, the fuel flows smoothly at the fuel electrode, sufficiently reacts, and the output can be sufficiently increased.

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

  FIG. 2 is a diagram showing an in-vehicle fuel cell system according to the first embodiment of the present invention.

  In the figure, reference numeral 11 denotes a stacked fuel cell, and in the first embodiment, a fuel cell stack constituting a polymer electrolyte fuel cell (PEFC). The fuel cell stack 11 includes passenger cars, buses, trucks. It is installed as an energy supply source in vehicles such as passenger carts and luggage carts. In this case, the vehicle is equipped with many auxiliary devices that consume electric energy even when the vehicle is stopped, such as a lighting device, a radio, a power window, etc., and can be driven in various driving patterns. There are many.

  Therefore, it is preferable to install a secondary battery as an auxiliary power storage device, a capacitor (capacitor) or the like as an energy supply source in addition to the fuel cell stack 11 in the vehicle.

  Further, 12 is an air supply system as a medium supply system for supplying air as a medium to the fuel cell stack 11, 13 is an air discharge system as a medium discharge system for discharging air from the fuel cell stack 11, and 14 Is a hydrogen gas supply system as a fuel supply system for supplying hydrogen gas as a fuel gas to the fuel cell stack 11, and 16 is a water supply as a cooling medium device unit for supplying water to the fuel cell stack 11. It is a system. The fuel cell stack 11, the air supply system 12, the air discharge system 13, the hydrogen gas supply system 14, and the water supply system 16 constitute an in-vehicle fuel cell system.

  In the first embodiment, a polymer electrolyte fuel cell (PEFC) is used as a fuel cell, but instead of the polymer electrolyte fuel cell, an alkaline aqueous fuel cell (AFC), phosphoric acid A type fuel cell (PAFC), a molten carbonate type fuel cell (MCFC), a solid oxide type fuel cell (SOFC), a hydrazine type fuel cell, a direct methanol type fuel cell (DMFC) or the like can also be used.

  The fuel cell stack 11 includes a stack case as a casing and a stack unit 11a accommodated in the stack case. The stack unit 11a is provided with a plurality of modules, a pair of terminals constituting the terminals of the fuel cell, and a pair of terminals constituting the terminals of the fuel cell, and the modules and the terminals, and is formed of an insulating material. Equipped with an insulator.

  By the way, in each module, the hydrogen gas supplied by the hydrogen gas supply system 14 and the oxygen contained in the air supplied as the oxidant by the air supply system 12 are reacted to generate water. A current is generated with the reaction. In this case, oxygen can be supplied as an oxidizing agent instead of air. For this purpose, the module is formed by stacking a plurality of thin membrane cells constituting the elements of the fuel cell stack 11 and electrically connecting them in series, and is composed of a collection of cells.

  Each cell sandwiches an electrolyte membrane (not shown) as a solid electrolyte (solid polymer electrolyte membrane) that transmits hydrogen ions, an air electrode composed of a reaction layer and a diffusion layer, and a fuel electrode composed of a reaction layer and a diffusion layer ( A membrane electrode assembly formed by disposing a hydrogen electrode), and separating each membrane electrode assembly and supplying the air to the air electrode A separator is provided that forms a fuel supply path with the path facing the fuel electrode.

  Each of the reaction layers is disposed on a surface of the air electrode and the fuel electrode in contact with the electrolyte membrane, and in order to promote a reaction between hydrogen and oxygen as a fuel, a platinum-based catalyst and a solid polymer are added to carbon. The substance formed into a paste form by mixing is composed of a catalyst layer formed by being uniformly dispersed with a certain thickness. Note that an oxygen electrode may be used instead of the air electrode to supply pure oxygen as a medium to the fuel cell stack 11.

  In the stack case, a supply manifold 22 as a first manifold for supplying and distributing the air supplied from the air supply system 12 to each air electrode above the stack unit 11a is provided in the stack unit. A discharge manifold 23 as a second manifold for collecting the gas in the air electrode and discharging it to the air discharge system 13 is formed below 11a. The supply manifold 22 and the discharge manifold 23 are communicated with the air supply path and shielded from the fuel supply path. Therefore, a plurality of grooves extending in the vertical direction are formed on the side of the separator facing the air electrode, and the air supply path is constituted by each groove. After the air is supplied to the supply manifold 22, the air is distributed to each air supply path, flows downward through the air supply path, and is discharged to the discharge manifold 23.

  The entire surface of the separator facing the fuel electrode is adhered and sealed to the adjacent membrane electrode assembly with an adhesive. Therefore, a plurality of horizontal fuel supply paths for supplying hydrogen gas to the fuel electrode are formed inside the sealed portion. In addition, 71 is a voltage sensor (V) as a voltage detection part which detects the electromotive voltage of a fuel cell.

  The air supply system 12 is sucked by a supply pipe 20 for supplying air to a supply manifold 22, a fan 21 including a sirocco fan as an oxidant supply device disposed in the supply pipe 20, and the like. A filter 24 for filtering air to be filtered. As the oxidant supply device, an air cylinder, an air tank, an oxygen cylinder, an oxygen tank or the like can be used instead of the fan 21.

  The air discharge system 13 includes a discharge pipe 30 for discharging air from the discharge manifold 23, a condenser 31 as a water recovery member disposed in the discharge pipe 30, and a temperature detection unit for detecting the temperature of the air. As a temperature sensor 32 (T) or the like.

  Therefore, by operating the fan 21, air taken from outside the vehicle can be supplied to the supply manifold 22. The air discharged from the discharge manifold 23 is supplied to the condenser 31 through the discharge pipe 30, and the vapor in the gas is condensed into water by the condenser 31. And the air after water is collect | recovered is discharged | emitted outside. The condenser 31 can be provided with a cooling fan (not shown) as a condensation promoting member. By increasing the rotational speed of the cooling fan and increasing the amount of air blown, the amount of steam condensation can be increased.

  The hydrogen gas supply system 14 is connected to a fuel supply device in which liquid hydrogen is stored, a fuel tank 41 as a hydrogen supply device, and the fuel tank 41, and discharges liquid hydrogen in the fuel tank 41 as hydrogen gas. A first fuel supply path 51 for connecting the first fuel supply path 51 to the fuel cell stack 11, and a second fuel supply path 52 formed in parallel with the second fuel supply path 52. And a fuel return path 53 that connects the first fuel supply path 51 and the fuel cell stack 11, a fuel discharge path 54 that is connected to the fuel feedback path 53, and discharges hydrogen gas.

  Then, the first pressure for detecting the pressure (primary pressure) of the hydrogen gas discharged to the first fuel supply path 51 from the fuel tank 41 side to the fuel cell stack 11 side in the first fuel supply path 51. A hydrogen pressure sensor (P) 42 as a detector, a pressure regulating valve 43A as a first fuel supply pressure adjusting unit for adjusting the pressure of hydrogen gas discharged to the first fuel supply path 51, and a hydrogen gas fuel cell An on-off valve 44A as a first fuel supply amount adjusting unit for adjusting the supply amount to the stack 11, and a second fuel supply pressure adjusting unit for further adjusting the pressure of the hydrogen gas adjusted by the pressure regulating valve 43A. The fuel cell stack is adjusted by a pressure valve 43B, an on-off valve 44B as a second fuel supply amount adjusting unit for further adjusting the supply amount of hydrogen gas adjusted by the on-off valve 44A, and a pressure regulating valve 43B. Hydrogen pressure sensor (P) 45 as a second pressure detector for detecting the pressure of the hydrogen gas immediately before being supplied to one (secondary pressure) is provided.

  Accordingly, when the hydrogen gas is discharged from the fuel tank 41, the pressure of the hydrogen gas is regulated by the pressure regulating valves 43A and 43B in the first fuel supply path 51, and is suitable for being supplied to the fuel cell stack 11. The pressure is supplied to the second fuel supply path 52 and supplied to the fuel cell stack 11. Note that two pressure regulating valves 43A and 43B are disposed in order to lower the pressure of the hydrogen gas stepwise, and three or more pressure regulating valves can be disposed as necessary. The on-off valves 44A and 44B not only adjust the supply amount of hydrogen gas to the fuel cell stack 11, but also supply or shut off the supply to the fuel cell stack 11.

  Further, a hydrogen concentration sensor (C) 46, a suction pump 47, and a check valve 48 as a fuel concentration detector are disposed in the fuel return path 53 from the fuel cell stack 11 side to the fuel tank 41 side. A valve 48 is connected to the first fuel supply path 51. The fuel discharge path 54 is connected between the suction pump 47 and the check valve 48 in the fuel return path 53, and the check valve 55 and the discharge are sequentially connected to the fuel discharge path 54 from the fuel return path 53 side. A solenoid valve 56 and a combustor (not shown) are provided. The hydrogen gas sent to the combustor through the discharge electromagnetic valve 56 is burned in the combustor to become water, and is discharged into the atmosphere. The check valve 48 allows hydrogen gas to flow from the suction pump 47 side to the hydrogen pressure sensor 45 side, and prevents hydrogen gas from flowing from the hydrogen pressure sensor 45 side to the suction pump 47 side. Further, the check valve 55 allows the hydrogen gas to flow from the suction pump 47 side to the discharge electromagnetic valve 56 side, and prevents the hydrogen gas from flowing from the discharge electromagnetic valve 56 side to the suction pump 47 side.

  Instead of the fuel tank 41, a hydrogen storage alloy tank that stores a hydrogen storage alloy filled with hydrogen gas can also be used. In that case, since the hydrogen storage alloy has the property of releasing hydrogen gas at room temperature and storing hydrogen gas at low temperature, the pressure of the hydrogen gas is adjusted only by changing the opening of the pressure regulating valves 43A and 43B. be able to. In a cold region, since the fuel cell vehicle is placed in an extremely low temperature environment, the hydrogen storage alloy does not release hydrogen gas. Therefore, when the temperature of the outside air becomes lower than the set value, a heater as a heating unit (not shown) is energized to heat the hydrogen storage alloy.

  In addition, although reforming apparatus can reform methanol, gasoline, etc. to generate hydrogen gas and supply the hydrogen gas directly to the fuel cell stack 11, it is stable even when the fuel cell vehicle is running at high load. In order to supply a sufficient amount of hydrogen, the fuel tank 41 is preferably used.

  The water supply system 16 injects water discharged from the water tank 61, a water tank 61 as a medium supply source, a pump 62 as a water supply device, an injection device (injector) 63 as an air electrode cooling device, and the like. The supply pipe 60 for supplying to the device 63 and the lower part of the discharge manifold 23 are collected, and the water discharged from the discharge manifold 23 and the water separated in the condenser 31 are collected and stored in the water tank 61. A water return path 59 for supply, a water recovery pump 65 for supplying recovered water to the water tank 61, a check valve 66 disposed between the water recovery pump 65 and the water tank 61, and the like are provided. The check valve 66 allows water to flow from the water recovery pump 65 side to the water tank 61 side, and prevents water from flowing from the water tank 61 side to the water recovery pump 65 side.

  It is possible to adjust the pressure of water supplied to the injection device 63 by detecting a load applied to the fuel cell vehicle by a control device (not shown) and adjusting the voltage applied to the pump 62 corresponding to the load. it can.

  Further, the water separated from the air in the condenser 31 flows through the water return path 59 and is finally discharged to the water tank 61 and stored in the water tank 61. The water tank 61 includes a water level sensor (L) 64 as a water level detection unit, and the water level sensor 64 detects the level of water in the water tank 61, that is, the water level. When the water level falls below a preset lower limit value, an alarm (not shown) as a notification member blinks to notify the operator that water is insufficient. In this case, for example, the operator increases the capacity of the condenser 31 by increasing the rotational speed of the cooling fan disposed in the condenser 31 and increases the amount of collected water.

  In addition, when the water level becomes equal to or higher than a preset upper limit value, it is possible to notify the operator that the water is excessive. In that case, for example, the operator lowers the capacity of the condenser 31 by lowering the rotational speed of the cooling fan, thereby reducing the amount of water recovered. In addition, the water level sensor 64 and the cooling fan can be connected to a control device (not shown), and the rotation speed of the cooling fan can be automatically changed according to the water level detected by the water level sensor 64.

  By the way, the air electrode functions as a cathode, the fuel electrode functions as an anode, air is supplied to the air electrode, hydrogen gas is supplied to the fuel electrode, and a load device is connected to the air electrode and the fuel electrode via the separator. Catalytic reaction takes place at the electrode, hydrogen is decomposed into hydrogen ions and electrons, and the hydrogen ions move to the air electrode side in the electrolyte membrane containing moisture in the form of protons, combined with oxygen in the air to form water. Is generated. Further, electrons generated at the fuel electrode move to the air electrode side via the load device, and a current is generated accordingly. That is, a current is generated by reacting hydrogen and oxygen, and the current can be supplied to the load device via the separator.

  A part of the hydrogen gas discharged from the fuel electrode to the fuel return path 53 is intermittently discharged into the atmosphere as exhaust gas through the fuel discharge path 54, so that a discharge solenoid valve is provided in the fuel discharge path 54. 56 is arranged. In this case, when the load on the fuel cell vehicle is increased, the amount of hydrogen gas supplied to the fuel electrode is increased, so that the amount of hydrogen gas discharged from the fuel electrode is also increased. Therefore, the control device intermittently opens and closes the discharge electromagnetic valve 56 according to the load of the vehicle equipped with the fuel cell, and increases the time for opening the discharge electromagnetic valve 56 when the load increases. Further, the remaining hydrogen gas discharged from the fuel electrode flows through the fuel return path 53 and then returns to the first fuel supply path 51. In addition, all the hydrogen gas discharged | emitted from the fuel electrode can also be discharged | emitted in air | atmosphere.

  In the first embodiment, the load device includes an inverter (not shown) that converts a direct current into a phase current, and a drive motor (not shown) that is driven by being supplied with the phase current. The voltage generated by the fuel cell stack 11 is detected by a voltage sensor as a first detection unit, and the current generated by the fuel cell stack 11 is detected by a current sensor (not shown) as a second detection unit. Is done.

  In the first embodiment, the control device includes an arithmetic device such as a CPU and an MPU, a storage device such as a semiconductor memory, an input / output interface, and the like. And each sensor as detection parts, such as the temperature sensor 32, the water level sensor 64, the hydrogen pressure sensors 42 and 45, the hydrogen concentration sensor 46, and the voltage sensor 71, is connected to the said control apparatus, and the sensor output of each sensor is sent. . In addition, actuators such as the fan 21, the pump 62, the water recovery pump 65, the pressure regulating valves 43A and 43B, the on-off valves 44A and 44B, the suction pump 47, and the discharge electromagnetic valve 56 are connected to the control device. The operation of each actuator is controlled based on the sensor output.

  Next, a module as a unit unit constituting the fuel cell stack 11 will be described.

  3 is a plan view showing the main part of the module according to the first embodiment of the present invention, FIG. 4 is a front view of the module according to the first embodiment of the present invention, and FIG. 5 is the first embodiment of the present invention. FIG. 6 is a perspective view showing a main part of the separator according to the first embodiment of the present invention.

  The module 10 is configured by stacking a plurality of sets including a cell 101, a separator 102 for electrically connecting two cells 101, and two types of frames 117 and 118 for supporting the cell 101 and the separator 102 in the thickness direction. Is done. The frames 117 and 118 are alternately stacked as spacers so that the cells 101 are arranged with a predetermined gap.

  The cell 101 includes an electrolyte membrane 111, an air electrode 112 disposed on one side of the electrolyte membrane 111, and a fuel electrode 113 disposed on the other side of the electrolyte membrane 111.

  The separator 102 is disposed on one side of the separator substrate 116 as a gas blocking member that blocks air and hydrogen between the cells 101 and in contact with the air electrode 112. Further, an air electrode side collector 114 as a first collector and a fuel electrode side collector 115 as a second collector disposed on the other side of the separator substrate 116 and in contact with the fuel electrode 113 are provided. . The air electrode side collector 114 is made of a mesh-like conductor, and has a large number of openings 143 (in FIG. 6, for convenience of explanation, the openings 143 are only partially shown to allow the mixed flow of air and water to pass through. Is formed). The fuel electrode side collector 115 is made of a mesh-like conductor, and a large number of openings 153 are formed to allow the fuel to pass therethrough. The air electrode side collector 114 is in contact with the diffusion layer of the air electrode 112 of the cell 101, and the fuel electrode side collector 115 is in contact with the reaction layer of the fuel electrode 113, thereby leading the current to the outside.

  In the present embodiment, the air electrode side collector 114 and the fuel electrode side collector 115 are made of a metal thin plate (expanded metal plate material) having a plate thickness of about 0.2 mm, and the separator substrate 116 is an air electrode. For example, stainless steel, nickel alloy, titanium alloy, etc., which is made of a thin metal plate thinner than the side collector 114 and the fuel electrode side collector 115 and has conductivity and corrosion resistance (corrosion resistance), is subjected to corrosion resistance conductive treatment such as gold plating. The one given is used. The frames 117 and 118 are made of an appropriate insulating material.

  The air electrode side collector 114 includes fine ridges 124 formed by pressing. The ridges 124 are formed at regular intervals in parallel to the vertical side (short side) of the plate material. The height of the ridge 124 is substantially equal to the thickness of the frame 117 to ensure the air supply path fa. The flat surface of the bottom portion 141 of each ridge 124 serves as a contact portion that contacts the diffusion layer of the air electrode 112, and the top portion 142 of each ridge 124 serves as a contact portion that contacts the separator substrate 116.

The air electrode side collector 114 is subjected to a hydrophilic treatment, and as a treatment method, a method of applying a hydrophilic treatment agent to the surface is adopted. As the treatment agent to be applied, polyacrylamide, polyurethane resin, titanium oxide (TiO ₂ ) or the like is used. As other hydrophilic treatment, there is a treatment for roughening a metal surface, for example, a plasma treatment. The hydrophilic treatment is preferably performed on a portion where the temperature is highest, for example, on the bottom 141 in contact with the cell 101, particularly on the air supply path fa. Thus, by performing the hydrophilic treatment, wetting of the contact surface between the air electrode side collector 114 and the diffusion layer of the air electrode 112 is promoted, and the cooling effect due to the latent heat of water can be improved. This also makes it difficult for the opening 143 to be clogged with water, thereby further reducing the possibility that the water will block the supply of air.

  On the other hand, the fuel electrode side collector 115 includes fine ridges 125 formed by pressing. The ridges 125 are formed in parallel to the horizontal side (long side) of the plate material at equal intervals. The height of the ridge 125 is substantially equal to the thickness of the frame 118 to ensure the fuel supply path fb. The flat surface of the bottom portion 151 of each ridge 125 serves as a contact portion that contacts the diffusion layer of the fuel electrode 113, and the top portion 152 of each ridge 125 serves as a contact portion that contacts the separator substrate 116.

  The air electrode side collector 114 and the fuel electrode side collector 115 are arranged with the separator substrate 116 interposed therebetween so that the bottom portions 141 and 151 are located outside. At this time, the top portions 142 and 152 are in contact with the separator substrate 116 and are in a state where they can be energized.

  Then, air flows in the direction of arrow A in the air supply path fa, and hydrogen flows in the direction of arrow B in the fuel supply path fb.

  Frames 117 and 118 are disposed outside the separator 102, respectively. In the fuel cell stack 11 (FIG. 2), each frame 117 other than the outermost frame 117 is formed by vertical frame portions 171 and 172 disposed at the left and right ends of the air electrode side collector 114, and the outermost frame 117. The frame 117 is formed by vertical frame portions 171 and 172 and backup plates 176 and 177 that connect the upper and lower ends of the vertical frame portions 171 and 172, and has a frame shape. In addition, the frame 118 is disposed on the periphery of the fuel electrode side collector 115 and the cell 101 and has a frame shape.

  Each of the vertical frame portions 171 and 172 includes long holes 173 and 174 penetrating in the plate thickness direction, and each of the vertical frame portions 181 and 182 includes long holes 183 and 184 penetrating in the plate thickness direction, respectively. When the frames 117 and 118 are stacked, a fuel flow path is formed by the long holes 173, 174, 183, and 184.

  In the fuel cell stack 11 configured as described above, the mixture of air and water mixed in the supply manifold 22 is supplied from above to the air supply path fa on the air electrode 112 side, and the air supply path fa is moved in the direction of arrow A (vertical direction). ). The mixture is supplied along the air electrode 112 in a state where water droplets are mixed in the form of a mist in the air. However, in the steady operation state of the fuel cell stack 11, the cell 101 generates heat due to the reaction. The mixture is heated in fa, and some of the water droplets in the mixture adhere to the mesh portion of the air electrode side collector 114 and the air electrode 112 of the cell 101, and the rest are the air electrode side collector 114 and the air electrode 112. When heated in the gas phase between the two, it becomes vapor and takes heat from the air electrode side collector 114 with latent heat of vaporization. Further, the vapor prevents moisture in the electrolyte membrane 111 from evaporating from the air electrode 112 side and keeps the moisture. Excess air and steam in the air supply path fa are discharged from the discharge manifold 23.

  On the other hand, the fuel is supplied from the side to the fuel supply path fb on the fuel electrode 113 side through the flow path formed by the elongated holes 173 and 183 of the frames 117 and 118 that are sequentially stacked, and the fuel supply path fb. Flows in the direction of arrow B (lateral direction). Of the hydrogen flowing along the fuel electrode 113, the surplus that did not participate in the reaction is discharged to the flow path formed by the long holes 174 and 184 on the opposite side.

  By the way, for example, when the driver depresses the accelerator pedal to accelerate the fuel cell vehicle, or travels on an uphill road, the accelerator pedal is released to decelerate the fuel cell vehicle, When the fuel cell changes from a high-load operation state to a low-load operation state when the vehicle changes to a low-load operation state such as traveling on a slope, the temperature of the fuel cell stack 11 decreases accordingly, and the separator substrate The water vapor may condense on the surface of the fuel supply path fb side of 116 and water droplets may adhere. In particular, in the fuel cell stack 11 in which the output is increased and the stacking density is increased, the cell 101 is thinned and a metal separator is used as the separator 102. In this case, the heat capacity of the cell 101 is reduced, and water vapor is reduced. Since it becomes easy to condense, the water droplets once adhered will not be excluded. As a result, the hydrogen gas does not flow smoothly on the fuel electrode 113 side, the catalytic reaction is not sufficiently performed, and as a result, the output is reduced.

  Therefore, when the fuel cell stack 11 changes from a high-load operation state to a low-load operation state, a temperature change mitigation unit, which will be described later, is disposed in the fuel electrode side collector 115 so that water droplets do not adhere. .

  FIG. 1 is a conceptual diagram showing a state of a fuel electrode side collector in the first embodiment of the present invention, FIG. 1 (a) is a front view of the fuel electrode side collector, and FIG. 1 (b) is a side view of the fuel electrode side collector. FIG.

  In the figure, reference numeral 115 denotes a fuel electrode side collector. The fuel electrode side collector 115 faces the air electrode side facing surface S1 as the first surface facing the separator substrate 116 (FIG. 3) and the fuel electrode 113. It has a fuel electrode side facing surface S2 as a second surface. The fuel electrode side collector 115 has a rectangular shape, and the bottoms 151 and the tops 152 of the ridges 125 are alternately formed. In the figure, the opening 153 is drawn to have a circular shape for convenience of explanation.

  Further, in order to prevent the temperature of the cell 101 from changing between a high-load operation state and a low-load operation state, a plurality of temperature change mitigation units are provided in the fuel electrode side collector 115 at predetermined intervals. The phase change element 181 is embedded. The phase change element 181 contains a phase change agent such as paraffin in a resin capsule having a spherical shape, for example.

  In the present embodiment, the temperature of the end portion of the stack unit 11a (FIG. 2) is likely to decrease. Therefore, the phase change element 181 is embedded in the fuel electrode side collector 115 of the module disposed at least at the end portion. Is preferred.

  The phase change agent becomes a first phase at a predetermined temperature τ1 or more, and in the present embodiment, becomes a liquid phase. When the temperature changes below the temperature τ1, the second phase, in this embodiment, a solid phase. become. When the temperature rises, the temperature τ1 is maintained until all of the phase change agent changes from the solid phase to the liquid phase, and when the temperature decreases, the temperature change decreases until all of the phase change agent changes from the liquid phase to the solid phase. The temperature τ1 is maintained. In the present embodiment, the phase change agent is selected so that the temperature τ1 is higher than the temperature at which water droplets are formed on the fuel electrode 113 side, that is, the dew point.

  By the way, when the fuel cell stack 11 is placed in a high-load operation state, the temperature of the cell 101 becomes high, and the temperature of the fuel electrode 113, the separator 102, etc. becomes higher than the temperature τ1. As a result, the phase change agent becomes a liquid phase. Subsequently, when the fuel cell stack 11 changes from a high-load operation state to a low-load operation state, the temperature of the cell 101 decreases, and accordingly, the temperatures of the fuel electrode 113, the separator 102, and the like decrease. At τ1, the phase change agent initiates a phase change from the liquid phase to the solid phase. During the phase change, the fuel electrode 113, the separator 102, and the like are maintained at the temperature τ1.

  When all of the phase change agent changes from the liquid phase to the solid phase, the phase change is completed. Until then, the phase change agent is maintained at the temperature τ1, and the fuel electrode 113, the separator 102, etc. are kept at a constant temperature τ1. Maintained.

  Therefore, water vapor is not condensed and water droplets are not formed on the fuel electrode 113 side. In particular, in the fuel cell stack 11 in which the target output is increased and the stacking density is increased, the cell 101 is thinned, a metal separator is used as the separator 102, and the heat capacity of the cell 101 is reduced, but water droplets are formed. Never happen.

  As a result, hydrogen gas flows smoothly in the fuel electrode 113, a sufficient catalytic reaction is performed, and the output can be sufficiently increased.

  Next, a second embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st Embodiment, the description is abbreviate | omitted by providing the same code | symbol, and the effect of the same embodiment is used about the effect of the invention by having the same structure. .

  FIG. 7 is a cross-sectional view showing the main part of the cell according to the second embodiment of the present invention.

  In the figure, reference numeral 161 denotes a separator. The separator 161 includes a main body portion 162 and convex portions 163 formed at a plurality of positions in the longitudinal direction of the main body portion 162 at an equal pitch, and has a comb-teeth shape. Have The separator 161 is disposed to face the cell 101, and a fuel supply path fb is formed between the convex portions 163. In addition, a plurality of phase change elements 165 as temperature change mitigating parts are applied to the surface of the main body 162 that faces the fuel electrode 113.

It is a conceptual diagram which shows the state of the fuel electrode side collector in the 1st Embodiment of this invention. It is a figure which shows the vehicle-mounted fuel cell system in the 1st Embodiment of this invention.

It is a top view which shows the principal part of the module in the 1st Embodiment of this invention. It is a front view of the module in the 1st Embodiment of this invention. It is a rear view of the module in the 1st Embodiment of this invention. It is a perspective view which shows the principal part of the separator in the 1st Embodiment of this invention. It is sectional drawing which shows the principal part of the cell in the 2nd Embodiment of this invention.

Explanation of symbols

101 Cell 102, 161 Separator 111 Electrolyte membrane 112 Air electrode 113 Fuel electrode 165, 181 Phase change element fa Air supply path fb Fuel supply path

Claims (3)

  A plurality of cells including an electrolyte membrane, an air electrode disposed on one side of the electrolyte membrane, and a fuel electrode disposed on the other side of the electrolyte membrane, and disposed adjacent to each cell. A fuel gas and air respectively supplied to the cell; and a separator that forms an air supply path with the air electrode and a fuel supply path with the fuel electrode. A fuel cell comprising a temperature change mitigation unit for mitigating a temperature change of a cell when a load applied to the battery changes.   The fuel cell according to claim 1, wherein the temperature change relaxation unit is a phase change element embedded in a separator. The fuel cell according to claim 1, wherein the temperature change relaxation part is a phase change element applied to a separator.

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