JP2008251204A - Fuel cell device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the mounting performance of a fuel cell device which is high in drainage performance from a fuel passage, and is eliminated in the necessity for inclining the device as a whole when mounting the fuel cell device to a vehicle by inclining the bottom face of the fuel passage formed along the fuel pole of a fuel cell. <P>SOLUTION: In this fuel cell device, fuel cells in each of which an electrolyte layer is held between the fuel electrode and an oxygen electrode are laminated with a first collector forming the fuel gas passage along the fuel electrode, a second collector forming an oxidizer gas passage along the oxygen electrode. and a separator to interrupt fuel gas and oxygen gas held between them. A side at the lower side of the fuel cell is inclined so that the downstream side of the fuel gas passage becomes lower. <P>COPYRIGHT: (C)2009,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 an alkaline aqueous solution (AFC), phosphoric acid (PAFC), molten carbonate (MCFC), solid oxide (SOFC), direct methanol (DMFC), etc. 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, moisture generated by the electrochemical reaction moves as proton-entrained water from the fuel electrode side to the oxygen electrode side, and reverses from the oxygen electrode side to the fuel electrode side. Move as diffusion water. Thereby, both sides of the solid polymer electrolyte membrane are maintained in a wet state. However, when the amount of moisture increases, the hydrogen gas flow path is locally blocked by moisture on the fuel electrode side, and the performance of the fuel cell deteriorates or the oxygen electrode deteriorates. It is known.

Therefore, a drainage flow path is connected to the lower surface of the reaction gas discharge manifold for connecting a reaction gas discharge pipe to the outlet of the reaction gas flow path, and the entire fuel cell device is tilted so that moisture is supplied from the reaction gas flow path to the reaction gas. There has been proposed a technique for making the current density uniform by facilitating the outflow to the discharge manifold and preventing the retention of moisture (for example, see Patent Document 1).
JP 2004-207106 A

  However, in the conventional fuel cell device, since the entire device must be tilted, when the fuel cell device is mounted on a vehicle, a large space for mounting is required, and the mountability is reduced. .

  The present invention solves the problems of the conventional fuel cell device, and by tilting the bottom surface of the fuel flow path formed along the fuel electrode of the fuel cell, the drainage from the fuel flow path is high, It is an object of the present invention to provide a fuel cell device having high mountability without requiring the entire device to be inclined when the fuel cell device is mounted on a vehicle.

  Therefore, in the fuel cell device of the present invention, the fuel cell in which the electrolyte layer is sandwiched between the fuel electrode and the oxygen electrode includes a first current collector that forms a fuel gas flow path along the fuel electrode, and an oxygen A fuel cell device laminated with a second current collector that forms an oxidant gas flow path along an electrode and a separator that cuts off the fuel gas and the oxidant gas, the fuel cell device being under the fuel electrode This side is inclined so that the downstream side of the fuel gas flow path is lowered.

  In another fuel cell device of the present invention, a fuel through hole connecting a plurality of adjacent fuel gas flow paths penetrating in the stacking direction of the fuel cells and positioned downstream of the fuel gas flow path And a water discharge conduit connected to the bottom of at least a part of the fuel through hole.

  In still another fuel cell device of the present invention, the first current collector further includes a groove that is inclined so that the downstream side of the fuel gas flow path is lowered.

  In still another fuel cell device of the present invention, the fuel cell device further includes a plurality of cell modules in which a plurality of the fuel cells are stacked, and the direction in which the fuel gas flows meanders so as to be folded back for each cell module.

  According to the configuration of claim 1, drainage from the fuel flow path is high, and when the fuel cell device is mounted on the vehicle, it is not necessary to incline the entire device, and the mountability on the vehicle can be increased. . Further, the fuel electrode is not covered with water, and it is possible to prevent the performance of the fuel cell from being lowered and the oxygen electrode from being deteriorated.

  According to the second aspect of the present invention, the water discharged from the fuel flow path and flowing into the fuel through hole is smoothly discharged, so that the drainage from the fuel flow path is further improved.

  According to the configuration of the third aspect, the water in the fuel channel is discharged from the fuel channel more quickly and more smoothly.

  According to the configuration of the fourth aspect, even if the flow path length of the fuel gas is increased, the water in the fuel flow path can be reliably discharged.

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

  FIG. 2 is a perspective view showing the configuration of the fuel cell stack according to the first embodiment of the present invention. FIG. 3 is an exploded view showing the configuration of the unit cell and separator set according to the first embodiment of the present invention. FIG. 4 is a diagram showing a configuration of the fuel cell system according to the first embodiment of the present invention.

  In the figure, 20 is a fuel cell stack as a fuel cell device composed of a plurality of fuel cells (FC), and is used as a power source for vehicles such as passenger cars, buses, trucks, passenger carts, luggage carts and the like. The Here, the vehicle is equipped with a large number of auxiliary equipment that consumes electricity, such as lighting devices, radios, and power windows. Since the output range is extremely wide, it is desirable to use the fuel cell stack 20 as a power source in combination with a battery, a secondary battery such as a lithium ion battery, and a power storage means including a capacitor.

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

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

  In this case, the solid polymer electrolyte membrane is sandwiched between two gas diffusion electrodes and integrated to join. Then, when one of the gas diffusion electrodes is used as a fuel electrode, and hydrogen gas as a fuel gas is supplied to the fuel electrode via a fuel flow path in contact with the surface of the fuel electrode, hydrogen is decomposed into hydrogen ions (protons) and electrons. Then, hydrogen ions permeate the solid polymer electrolyte membrane. Further, when the other of the gas diffusion electrodes is an oxygen electrode, and air as an oxidant is supplied to the oxygen electrode via an air channel as an oxidant channel in contact with the surface of the oxygen electrode, oxygen in the air, the hydrogen Ions and electrons combine to produce water. An electromotive force is generated by such an electrochemical reaction.

  For example, in the present embodiment, as an example, a PEM type fuel cell is used, for example, a stack in which 100 cells are connected in series is used. Although hydrogen gas, which is fuel taken out by reforming methanol, gasoline, etc. with a reformer, can be directly supplied to the fuel cell, a sufficient amount of hydrogen can be stably supplied even during high-load operation of the vehicle. It is desirable to supply the hydrogen gas stored in the fuel storage means 73 so that the fuel can be supplied.

  Here, the fuel storage means 73 is preferably a container storing a hydrogen storage alloy, but is a container storing a hydrogen storage liquid such as decalin, a container storing hydrogen gas such as a hydrogen gas cylinder, or the like. May be. Thereby, hydrogen gas is always sufficiently supplied at a substantially constant pressure, so that the fuel cell can follow the fluctuation of the load of the vehicle and supply a necessary current.

  In the present embodiment, the fuel cell stack 20 includes a plurality of cell modules 21 as shown in FIG. In addition, the arrow in FIG. 2 has shown the flow of the hydrogen gas as fuel gas. As shown in FIG. 3, the cell module 21 is configured to electrically connect unit cells (MEA: MEMBRANE ELECTRODE ASSEMBLY) 12 as fuel cells and the unit cells 12 to each other and to introduce hydrogen introduced into the unit cells 12. The separator 16 separates the fuel flow path through which the gas flows and the air flow path through which the air as the oxidant flows. The unit cell 12 and the separator 16 are set as one set, and a plurality of sets are stacked in the thickness direction. Configured. In the cell module 21, the unit cells 12 and the separators 16 are stacked in multiple stages with the frame 17 holding the periphery so that the unit cells 12 are arranged with a predetermined gap. Are stacked.

  The unit cell 12 is composed of an air electrode as an oxygen electrode provided on the solid polymer electrolyte membrane side 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. Further, the air electrode side collector 14 as a current collector for collecting current by contacting the electrode diffusion layer on the air electrode side of the unit cell 12 and the electrode diffusion layer on the fuel electrode side of the unit cell 12 for collecting current. A fuel electrode side collector 15 as a current collector is disposed between the unit cell 12 and the adjacent separator 16.

  In the unit cell 12, water moves. In this case, when a fuel gas, that is, hydrogen gas as an anode gas is supplied into the fuel flow path in contact with the fuel electrode surface, hydrogen is decomposed into hydrogen ions and electrons, and the hydrogen ions are accompanied by proton-entrained water and are solid. Permeates the polymer electrolyte membrane. 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 air flow path, oxygen in the air is combined with the hydrogen ions and electrons to generate water. The Moisture permeates through the solid polymer electrolyte membrane as back-diffused water and moves into the fuel flow path in contact with the fuel electrode surface. Here, the reverse diffusion water means that water generated in the air flow path diffuses into the solid polymer electrolyte membrane and permeates through the solid polymer electrolyte membrane in the direction opposite to the hydrogen ions to the fuel electrode. It has penetrated.

  In the fuel cell stack 20 shown in FIG. 2, a plurality of cell modules 21 are stacked so as to be stacked in the horizontal direction in the figure, and are sandwiched by side end holding portions 40 from both sides. In the example shown in FIG. 2, ten sets of unit cells 12 and separators 16 are stacked to form one cell module 21, and ten cell modules 21 are stacked to form one fuel cell stack 20. Is forming. Since the separators 16 are always provided on both sides of the unit cell 12, the number of separators 16 in one cell module 21 is eleven.

  In addition, fuel through-holes 35 functioning as slit-like fuel gas passages extending in the vertical direction are formed on both longitudinal sides of each frame 17 and separator 16. Then, in a state where the unit cell 12 and the separator 16 are stacked to form the cell module 21, the fuel through holes 35 of the frames 17 and the separator 16 are connected to each other and penetrate the cell module 21 in the thickness direction.

  The fuel cell stack 20 has a generally flat rectangular parallelepiped shape, and the air flow in the fuel cell stack 20 is the gravity direction as the vertical direction in FIG. 2 and is linear from top to bottom. Yes. Further, the flow of hydrogen gas is in a horizontal direction substantially perpendicular to the direction of gravity, and as shown by an arrow A in FIG. 2, in parallel to each other in each cell module 21, the fuel on the right side from the left fuel through hole 35. The flow is directed toward the through-hole 35 for use.

  In the example shown in FIG. 2, a second fuel supply that supplies hydrogen gas to an introduction-side fuel through hole 35 a, which will be described later, as a fuel through-hole 35 that opens near the left end of the front-side side end holding portion 40. A pipe 33 is connected, and hydrogen gas is introduced into the fuel cell stack 20 from here. Further, although not shown in FIG. 2 as the fuel through hole 35 opened near the right end of the rear side end holding portion 40, the first gas gas is discharged to the discharge side fuel through hole 35b described later. A fuel discharge line 31 is connected, from which hydrogen gas is discharged.

  A water discharge opening (not shown) is formed at an appropriate position at the bottom of the discharge-side fuel through hole 35b, and a drain pipe 38 serving as a water discharge conduit is connected to the water discharge opening. In the illustrated example, one water discharge opening is formed in each cell module 21, and a drain branch pipe 38a is connected to each of the water discharge openings. The number and the like can be changed as appropriate. Further, the drain pipe 38 is collected in one drain collecting pipe 38b, and water is discharged out of the fuel cell stack 20 from the drain collecting pipe 38b. The drain collecting pipe 38b is preferably connected in the middle of the first fuel discharge pipe 31. A water discharge control opening / closing valve 39 is disposed in the middle of the drain collecting pipe 38b.

  In the present embodiment, the fuel cell system has a system for supplying hydrogen gas to the fuel cell stack 20, as shown in FIG. The hydrogen gas is supplied from the fuel storage means 73 to a first fuel supply line 32 as a fuel supply line, and a second fuel supply line as a fuel supply line connected to the first fuel supply line 32. Through 33, the fuel gas is supplied to the inlet of the fuel gas flow path of the fuel cell stack 20. The first fuel supply pipe 32 is provided with a fuel supply electromagnetic valve 26 as a hydrogen supply electromagnetic valve. The second fuel supply pipe 33 is provided with a pressure sensor 78 as pressure detecting means for detecting the pressure in the fuel flow path. The fuel storage means 73 has a sufficiently large capacity and always has a capability of supplying hydrogen gas at a sufficiently high pressure. In addition, the said fuel storage means 73 may be single, may be plural, and may be any number in the case of plural.

  The hydrogen gas discharged as an unreacted component from the outlet of the fuel flow path of the fuel cell stack 20 is discharged to the outside of the fuel cell stack 20 through the first fuel discharge pipe 31 serving as a fuel discharge pipe. . The first fuel discharge pipe 31 is provided with a water recovery drain tank 60 as a recovery container. The water recovery drain tank 60 is connected with a second fuel discharge pipe 30 as a fuel discharge pipe for discharging water and separated hydrogen gas, and the second fuel discharge pipe 30 has a hydrogen circulation line. A suction circulation pump 36 as a pump is provided. Further, a hydrogen circulation electromagnetic valve 34 as a hydrogen circulation switching electromagnetic valve is disposed in the second fuel discharge pipe 30. The end of the second fuel discharge line 30 opposite to the water recovery drain tank 60 is connected to the second fuel supply line 33. Thereby, the hydrogen gas led out of the fuel cell stack 20 can be recovered and supplied to the fuel gas flow path of the fuel cell stack 20 for reuse.

  The water recovery drain tank 60 also functions as a suction tank for storing hydrogen gas discharged from the fuel gas passage when the operation of the fuel cell system is stopped. Therefore, the capacity of the water recovery drain tank 60 is such that when air as a replacement gas is introduced into the fuel gas flow path and hydrogen gas as the fuel gas is purged, the capacity of the water recovery drain tank 60 is increased. The remaining hydrogen gas is rapidly driven into the water recovery drain tank 60, and is set so as to be large enough not to remain in the fuel gas flow path. That is, even when the air is introduced into the fuel cell stack 20, the hydrogen gas remaining in the fuel gas flow path is rapidly removed even if the fuel gas flow path of the fuel cell stack 20 is not evacuated. The water recovery drain tank 60 has a sufficiently large capacity so that it does not move into the water recovery drain tank 60 and become mixed with oxygen in the air introduced in the fuel cell stack 20. Is.

  Further, a third fuel discharge pipe 56 as a fuel discharge pipe is connected between the suction circulation pump 36 and the hydrogen circulation solenoid valve 34 in the second fuel discharge pipe 30, and the third fuel discharge pipe The passage 56 is provided with a hydrogen start / stop solenoid valve 56a as a hydrogen exhaust solenoid valve. Thereby, hydrogen gas can be discharged at the end of the operation of the fuel cell stack 20.

  Further, the second fuel supply line 33 is connected to an outside air introduction line 28 as a purge means. The outside air introduction conduit 28 is provided with an outside air introduction solenoid valve 28a and an air filter 28b as air introduction solenoid valves, and the outside air as a replacement gas flows into the fuel gas flow when the operation of the fuel cell stack 20 ends. It can introduce | transduce into a path | route and can purge the hydrogen gas as fuel gas.

  Here, the fuel supply solenoid valve 26, the outside air introduction solenoid valve 28a, the hydrogen circulation solenoid valve 34, and the hydrogen start / stop solenoid valve 56a are so-called on-off type, such as an electric motor, a pulse motor, and an electromagnet. Actuated by an actuator consisting of 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. The air filter 28b removes dust, impurities, harmful gases and the like contained in the air.

  On the other hand, air as an oxidant is supplied to an air flow path of the fuel cell stack 20 from an oxidant supply source such as an air supply fan, an air cylinder, and an air tank (not shown) through an intake manifold and the like. 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 an exhaust manifold, a condenser, etc. which are not shown in figure.

  The intake manifold is provided with a water supply nozzle for spraying water to maintain the oxygen electrode (cathode electrode) of the fuel cell stack 20 in a wet state. Further, the oxygen electrode and the fuel electrode can be cooled by the sprayed water. Further, the condenser is for condensing and removing moisture contained in the air discharged from the fuel cell stack 20, and the water condensed by the condenser is collected in a water tank (not shown) Supplied to the supply nozzle.

  The secondary battery as the power storage means is a so-called battery (storage battery), and a lead storage battery, a nickel cadmium battery, a nickel hydrogen battery, a lithium ion battery, a sodium sulfur battery, and the like are common. The power storage means does not necessarily have to be a battery, and electrically stores and discharges energy, such as a capacitor (capacitor) such as an electric double layer capacitor, a flywheel, a superconducting coil, and a pressure accumulator. Any form may be used as long as it has a function. Furthermore, any of these may be used alone, or a plurality of them may be used in combination.

  The fuel cell stack 20 is connected to a load (not shown) and supplies the generated current to the load. Here, the load is generally an inverter device that is a drive control device, and converts a direct current from the fuel cell stack 20 or the power storage means into an alternating current to rotate a vehicle wheel. To supply. Here, the drive motor also functions as a generator, and generates a so-called regenerative current when the vehicle is decelerated. In this case, since the drive motor is rotated by the wheel to generate electric power, the wheel is braked, that is, functions as a vehicle braking device (brake). Then, the regenerative current is supplied to the power storage means, and the power storage means is charged.

  In the present embodiment, the fuel cell system has control means (not shown). The control means includes arithmetic means such as a CPU and MPU, storage means such as a magnetic disk and semiconductor memory, an input / output interface, and the like, and is supplied from various sensors to the fuel flow path and the air flow path of the fuel cell stack 20. By detecting the flow rate, temperature, output voltage, etc. of hydrogen, oxygen, air, etc., the oxidant supply source, fuel supply solenoid valve 26, outside air introduction solenoid valve 28a, hydrogen circulation solenoid valve 34, suction circulation pump 36, water The operation of the discharge control on / off valve 39, the hydrogen start / stop electromagnetic valve 56a, and the like are controlled. The control means also includes a timer for measuring the elapsed time since the supply of hydrogen gas to the fuel gas flow path of the fuel cell stack 20 is stopped. And the said control means controls the operation | movement of all the apparatuses which supply a fuel and an oxidizing agent to the fuel cell stack 20 in cooperation with another sensor and another control apparatus.

  Next, the configuration of the fuel flow path in the fuel cell stack 20 will be described in detail.

  FIG. 1 is a diagram showing the configuration of the fuel flow path of the fuel cell stack according to the first embodiment of the present invention. FIG. 5 is the configuration of the fuel electrode side collector of the fuel cell stack according to the first embodiment of the present invention. FIG.

  FIG. 1 shows the fuel flow path side surface of the unit cell 12 held by the frame 17, that is, the fuel electrode. In the present embodiment, the shape of the fuel electrode in the unit cell 12 is trapezoidal, the sides extending in the vertical direction on both the left and right sides are parallel to each other, the upper side is horizontal, and the lower side is inclined. It has become a trapezoid. The upper side coincides with the upper surface of the fuel flow path, and the lower side coincides with the bottom face 18 of the fuel flow path.

  And hydrogen gas distribute | circulates the inside of the said fuel flow path toward the right from the left in FIG. Therefore, as the fuel flow path goes downstream, the bottom surface 18 becomes lower and the cross-sectional area becomes larger. The vertical dimension of the introduction side fuel through hole 35a for introducing hydrogen gas into the fuel flow path corresponds to the vertical dimension of the left side of the fuel flow path, and the discharge side for discharging hydrogen gas from the fuel flow path. The vertical dimension of the fuel through-hole 35b corresponds to the vertical dimension of the right side of the fuel flow path. As a result, the vertical dimension of the introduction side fuel through hole 35a is smaller than the vertical dimension of the discharge side fuel through hole 35b.

  In addition, as described in “Background Art”, the hydrogen gas in the fuel flow path contains moisture that has moved as back-diffused water from the oxygen electrode side toward the fuel electrode side. When the pressure increases, it condenses and becomes condensed water, that is, liquid phase water. Then, when the water falls by the dead weight and reaches the bottom surface 18, as shown by an arrow B, the water flows toward the lower right along the inclined bottom surface 18, and is for the discharge side fuel. It flows into the through hole 35b. Since the bottom surface 18 is inclined, even if the flow rate of the hydrogen gas in the fuel flow path is low, water flows toward the lower right along the bottom surface 18 by its own weight. It flows into the discharge side fuel through hole 35b without staying.

  Furthermore, in the present embodiment, in order to make the flow of water in the fuel flow path smoother, as shown in FIG. 5, the groove 15 b formed in the fuel electrode side collector 15 is also formed with the bottom surface 18. Similarly, it is inclined. The fuel electrode side collector 15 has the same shape as the surface of the unit cell 12 on the fuel flow path side, and the lower side 15a coincides with the bottom surface 18 of the fuel flow path. That is, the lower side 15a is inclined in the same manner as the bottom surface 18, and is parallel to the groove 15b.

  As described above, since the groove 15b is inclined, the water in the fuel flow path flows toward the lower right along the groove 15b when it reaches the groove 15b without falling to the bottom surface 18. Then, it flows into the discharge-side fuel through hole 35b. Therefore, the water in the fuel channel is discharged from the fuel channel more quickly and smoothly.

  Further, since the groove 15b also has a function of guiding the flow of hydrogen gas in the fuel flow path, when the hydrogen gas flows in the fuel flow path, the hydrogen gas is inclined diagonally to the right along the groove 15b and the bottom surface 18. Will flow towards. For this reason, the water in the fuel flow path flows toward the lower right along the groove 15b and the bottom surface 18 by the flow of hydrogen gas, and is discharged from the fuel flow path more quickly and smoothly. .

  Note that if the amount of moisture condensed in the fuel flow path is large, the fuel flow path may be locally blocked by water. Then, the performance of the unit cell 12 is deteriorated, or the fuel electrode of the unit cell 12 is deteriorated.

  Therefore, during steady operation of the fuel cell system, hydrogen gas is discharged at a predetermined timing, and the suction circulation pump 36 is operated to suck the hydrogen gas in the fuel flow path and discharge it from the fuel cell stack 20. Therefore, it is desirable to increase the flow rate of the hydrogen gas in the fuel flow path, and to blow off and discharge the water remaining in the fuel flow path. Thereby, a fuel electrode is not covered with water, and the fall of the performance of the unit cell 12 and the deterioration of an oxygen electrode can be prevented. The discharge process may be executed every predetermined cycle, may be executed every predetermined driving time, or executed every time the travel distance of the vehicle reaches a predetermined value. Alternatively, it may be executed at any time when water retention is detected due to a change in cell voltage or the like during traveling.

  Even when the operation of the fuel cell system is stopped, the flow rate of the hydrogen gas in the fuel channel increases when the hydrogen gas in the fuel channel is sucked by the suction circulation pump 36 and discharged into the atmosphere. The water staying in the fuel flow path is blown off and discharged. As a result, the fuel electrode is not covered with moisture, and the performance of the unit cell 12 can be prevented from deteriorating and the oxygen electrode can be prevented from deteriorating.

  The water discharged from the fuel flow path flows into the discharge side fuel through hole 35b. Therefore, in the present embodiment, as shown in FIG. 2, a drain pipe 38 is connected to the bottom of the exhaust side fuel through hole 35b. Therefore, the water flowing into the discharge side fuel through hole 35b is discharged from the bottom of the discharge side fuel through hole 35b through the drain pipe 38 without hindering the flow of hydrogen gas to the first fuel discharge pipe 31. Is done. When water is discharged from the drain pipe 38, the water discharge control on / off valve 39 is opened. When the drain collecting pipe 38b is connected in the middle of the first fuel discharge pipe 31, the water flowing into the drain pipe 38 flows into the first fuel discharge pipe 31, and the first fuel discharge pipe 31 Together with the hydrogen gas flowing through the fuel cell 31, the fuel cell stack 20 is discharged.

  Thus, in the present embodiment, since the bottom surface 18 of the fuel flow path is inclined, even if the fuel cell stack 20 is installed horizontally, that is, so that the top surface of the fuel flow path is horizontal. However, the water in the fuel flow path flows obliquely downward along the bottom surface 18 and is quickly and smoothly discharged from the fuel flow path without staying in the fuel flow path. It flows into the through hole 35b. Therefore, drainage from the fuel flow path is high, the fuel electrode is not covered with water, and the performance of the unit cell 12 can be prevented from deteriorating and the fuel electrode can be prevented from deteriorating.

  In particular, it is possible to effectively prevent the occurrence of an abnormal potential at the time of starting or stopping, and to prevent deterioration of the catalyst layer. In addition, when the fuel cell stack 20 is mounted on a vehicle, it is not necessary to incline the entire fuel cell stack 20, so that a large space is not required and the mountability is improved.

  In addition, since the shape of the fuel electrode of the unit cell 12 is a trapezoid, the area of the fuel electrode is slightly reduced compared to the case where the shape of the fuel electrode is a rectangle, but the portion reduced by the trapezoid is as follows: It is located at the lowermost end of the fuel electrode, and it is a part that not only contributes to power generation but also tends to cause deterioration. Therefore, even if the area is reduced, it is preferable to reduce the part.

  Further, since the drain pipe 38 is connected to the bottom of the discharge-side fuel through hole 35b, the water discharged from the fuel flow path and flowing into the discharge-side fuel through-hole 35b passes through the discharge-side fuel through-hole 35b. It is smoothly discharged from the bottom through the drain pipe 38. Therefore, the drainage from the fuel flow path becomes higher.

  Furthermore, since the groove 15b formed in the fuel electrode side collector 15 is inclined and parallel to the bottom surface 18, water in the fuel flow path is discharged from the fuel flow path more quickly and smoothly. The

  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. The description of the same operation and the same effect as those of the first embodiment is also omitted.

  FIG. 6 is a perspective view showing the configuration of the fuel cell stack according to the second embodiment of the present invention, and FIG. 7 is a diagram showing the configuration of the fuel flow path of the fuel cell stack according to the second embodiment of the present invention. . FIG. 7A shows the configuration of the fuel flow paths in the odd-numbered cell modules, and FIG. 7B shows the configuration of the fuel flow paths in the even-numbered cell modules.

  In the present embodiment, as indicated by an arrow C in FIG. 6, the flow of hydrogen gas is in a serpentine shape that folds for each cell module 21 in a horizontal plane, that is, in a meandering shape. In the example shown in FIG. 6, the fuel cell stack 20 includes four cell modules 21, a first cell module 21-1 to a fourth cell module 21-4. In this case, the flow of hydrogen gas in the odd-numbered cell modules 21, that is, the first cell module 21-1 and the third cell module 21-3 is directed from the left to the right. The flow of hydrogen gas in the cell module 21, that is, the second cell module 21-2 and the fourth cell module 21-4 is from right to left.

  Therefore, as shown in FIG. 7A, the shape of the fuel electrode in the unit cell 12 of the odd-numbered cell module 21 is a trapezoid whose lower side is inclined to the lower right. The bottom surface 18 of the flow path is also inclined downward and to the right. On the other hand, as shown in FIG. 7 (b), the shape of the fuel electrode in the unit cell 12 of the even-numbered cell module 21 is a trapezoid whose lower side is inclined obliquely downward to the left. The bottom surface 18 of the flow path is also inclined to the lower left.

  In the present embodiment, the vertical dimension of the introduction-side fuel through hole 35a is equal to the vertical dimension of the discharge-side fuel through hole 35b. Further, in the odd-numbered cell module 21, the introduction side fuel through hole 35a is located on the left side, and the discharge side fuel through hole 35b is located on the right side. The side fuel through hole 35a is located on the right side, and the discharge side fuel through hole 35b is located on the left side.

  The water condensed in the fuel flow paths of the odd-numbered cell modules 21 falls along the inclined bottom surface 18 as indicated by an arrow D when the water flow drops by its own weight and reaches the bottom surface 18. Then, it flows toward the lower right and flows into the exhaust-side fuel through hole 35b. Since the bottom surface 18 is inclined, even if the flow rate of the hydrogen gas in the fuel flow path is low, water flows toward the lower right along the bottom surface 18 by its own weight. It flows into the discharge side fuel through hole 35b without staying.

  Further, when the water condensed in the fuel flow paths of the even-numbered cell modules 21 falls down the fuel flow path by its own weight and reaches the bottom surface 18, as shown by an arrow E, along the inclined bottom surface 18. Then, it flows toward the lower left and flows into the exhaust side fuel through hole 35b. Since the bottom surface 18 is inclined, even if the flow rate of hydrogen gas in the fuel flow path is low, water flows toward the lower left along the bottom surface 18 by its own weight. It flows into the discharge side fuel through hole 35b without staying.

  Further, in the present embodiment, as in the first embodiment, in order to make the flow of water in the fuel flow path smoother, the groove 15b formed in the fuel electrode side collector 15 is Like the bottom surface 18, it is inclined. That is, the fuel electrode side collector 15 in the odd-numbered cell module 21 has the same shape as the surface on the fuel flow path of the unit cell 12 as shown in FIG. 7A, and the lower side 15a is the bottom surface 18. Similarly, the groove 15b is inclined to the lower right, and the groove 15b is also inclined to the lower right in parallel with the bottom surface 18.

  The fuel electrode side collector 15 in the even-numbered cell module 21 has the same shape as the surface on the fuel flow path of the unit cell 12 as shown in FIG. 7B, and the lower side 15a is the bottom surface 18. Similarly, the groove 15b is inclined diagonally to the left, and the groove 15b is inclined parallel to the bottom surface 18 and diagonally downward to the left.

  A water discharge opening (not shown) is formed at an appropriate position at the bottom of the discharge-side fuel through hole 35b, and a drain pipe 38 is connected to the water discharge opening. In the example shown in FIG. 6, one water discharge opening is formed in each cell module 21, and a drain branch pipe 38a is connected to each of the water discharge openings. In this case, the drain side fuel through hole 35b in the odd-numbered cell module 21 is located on the right side, and the drain side fuel through hole 35b in the even numbered cell module 21 is located on the left side. They are arranged on the left and right respectively. In FIG. 6, only the right drain pipe 38 connected to the discharge side fuel through hole 35b in the first cell module 21-1 and the third cell module 21-3 is drawn, and the second cell is drawn. The left drain pipe 38 connected to the discharge side fuel through hole 35b in the module 21-2 and the fourth cell module 21-4 is hidden behind the fuel cell stack 20, and is not drawn. The left and right drain pipes 38 are connected to a drain collecting pipe 38b via a connecting pipe 38c that connects the drain pipes 38 to each other.

  Since the configuration and operation of other points are the same as those in the first embodiment, description thereof is omitted.

  Thus, in the present embodiment, the direction in which the bottom surface 18 of the fuel flow path in the odd-numbered cell module 21 inclines and the direction in which the bottom surface 18 of the fuel flow path in the even-numbered cell module 21 inclines are mutually. It is reversed. Therefore, the flow of hydrogen gas in the fuel cell stack 20 can be made meandering, and the flow path length of the hydrogen gas can be set long.

  Further, by disposing the drain pipes 38 on the left and right, respectively, water can be smoothly discharged from the discharge side fuel through holes 35b located on either the left or right.

  In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

It is a figure which shows the structure of the fuel flow path of the fuel cell stack in the 1st Embodiment of this invention. It is a perspective view which shows the structure of the fuel cell stack in the 1st Embodiment of this invention. It is an exploded view which shows the structure of the set of the unit cell and separator in the 1st Embodiment of this invention. It is a figure which shows the structure of the fuel cell system in the 1st Embodiment of this invention. It is a figure which shows the structure of the fuel electrode side collector of the fuel cell stack in the 1st Embodiment of this invention. It is a perspective view which shows the structure of the fuel cell stack in the 2nd Embodiment of this invention. It is a figure which shows the structure of the fuel flow path of the fuel cell stack in the 2nd Embodiment of this invention.

Explanation of symbols

12 unit cell 14 air electrode side collector 15 fuel electrode side collector 15b groove 16 separator 18 bottom surface 20 fuel cell stack 21 cell module 35 fuel through hole 35a introduction side fuel through hole 35b discharge side fuel through hole 38 drain pipe

Claims (4)

A fuel cell in which an electrolyte layer is sandwiched between a fuel electrode and an oxygen electrode.
A first current collector forming a fuel gas flow path along the fuel electrode;
A second current collector that forms an oxidant gas flow path along the oxygen electrode;
A fuel cell device laminated with a fuel gas and a separator for blocking oxidant gas interposed therebetween,
A fuel cell device in which a lower side of the fuel electrode is inclined so that a downstream side of the fuel gas flow path is lowered. A through-hole for fuel connecting a plurality of adjacent fuel gas flow paths penetrating in the stacking direction of the fuel cell; and
2. The fuel cell device according to claim 1, further comprising: a water discharge pipe connected to a bottom part of at least a part of the fuel through hole located downstream of the fuel gas flow path.   2. The fuel cell device according to claim 1, wherein the first current collector includes a groove that is inclined so that a downstream side of the fuel gas flow path is lowered. A plurality of cell modules in which a plurality of the fuel cells are stacked,
The fuel cell device according to claim 1, wherein the flow direction of the fuel gas meanders so as to be folded back for each cell module.

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