JP5353438B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell.

  A fuel cell is a device for obtaining electrical energy using hydrogen and oxygen as fuel. Since fuel cells have high conversion efficiency into energy and are excellent in terms of environment, they are widely developed as future energy supply systems.

  A general fuel cell includes a membrane-electrode assembly having an electrolyte membrane and a catalyst layer, a gas diffusion layer provided adjacent to the membrane-electrode assembly, and a separator in which a gas flow path is formed. ing. Conventionally, there has been known a comb-shaped gas flow path in which a supply flow path for supplying gas to a gas diffusion layer and a discharge flow path for recovering gas from the gas diffusion layer are alternately formed at predetermined intervals. Yes.

  In such a comb-shaped gas flow path, a gas flow path is known in which a drainage channel is provided at the tip of the supply gas channel and a part of the inlet to the drainage channel is closed with a porous body. (Patent Document 1). According to this configuration, only the water can be discharged from the front end portion of the supply gas flow path by adjusting the pressure on both sides of the porous body.

JP 2005-166545 A

  In the above-described comb-shaped gas flow path, the front end portion of the supply gas flow path is a dead end, and water is easily collected. If water accumulates at the tip of the supply gas flow path, gas diffusion from the supply gas flow path to the gas diffusion layer is hindered, resulting in a problem that power generation efficiency is reduced.

  According to the technique described in Patent Document 1, it is possible to suppress water accumulation by performing drainage from a drainage channel provided at the tip of the supply gas channel. However, in this configuration, since drainage is always performed from the front end portion of the supply gas flow path, the electrolyte membrane may be dried due to excessive drainage, which may reduce power generation efficiency.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel cell capable of improving power generation efficiency by appropriately controlling the amount of drainage from a supply gas flow path.

The fuel cell includes a membrane-electrode assembly, a pair of gas diffusion layers that sandwich the membrane-electrode assembly, and a pair of separators that sandwich the pair of gas diffusion layers. In addition, on at least one of the pair of separators on the gas diffusion layer side, a groove-shaped first gas flow path having an upstream end communicating with a supply manifold and a downstream end communicating with a drainage channel, and the first gas An increase / decrease means arranged at a communication part from the flow path to the drainage channel and capable of increasing / decreasing a flow passage cross-sectional area at the communication part, and provided on the gas diffusion layer side of the separator having the first gas flow path On this surface, a groove-shaped second gas flow path is provided in which the downstream end communicates with the discharge manifold and the upstream end is a dead end. According to this configuration, the amount of drainage from the first gas channel to the drainage channel can be controlled to an appropriate amount by adjusting the channel cross-sectional area with the increasing / decreasing means provided in the communication part. As a result, both the retention of water at the tip of the first supply gas flow path and the drying of the electrolyte membrane can be suppressed, so that the power generation efficiency of the fuel cell can be improved.

  In the above configuration, the increase / decrease means autonomously increases / decreases the channel cross-sectional area based on the relative humidity at the downstream end of the first gas channel or a parameter that can estimate the relative humidity. Can do. According to this configuration, since it is not necessary to provide a mechanism for controlling the increase / decrease means, the number of parts can be reduced.

  In the above configuration, based on the relative humidity at the downstream end of the first gas flow path, or an acquisition unit that acquires a parameter capable of estimating the relative humidity, and the relative humidity or the parameter acquired by the acquisition unit, Control means for controlling the increase / decrease of the cross-sectional area of the flow path by the increase / decrease means. According to this configuration, the flow path cross-sectional area can be adjusted more appropriately by controlling the increase / decrease means by the control means.

In the above configuration, the parameters include the temperature at the downstream end of the first gas flow path, the gas flow rate at the gas discharge port communicating with the downstream end of the discharge manifold, the output current of the fuel cell, and the output voltage of the fuel cell. It can be set as the structure which is at least one of them .

  According to the present invention, the power generation efficiency can be improved by appropriately controlling the amount of drainage from the supply gas passage.

FIG. 1 is a diagram illustrating the configuration of the fuel cell according to the first embodiment. FIG. 2 is an enlarged view of the communication portion in FIG. FIG. 3 is an enlarged view of a communication portion in the fuel cell according to the second embodiment. FIG. 4 is an enlarged view of a communication portion in the fuel cell according to the third embodiment. FIG. 5 is an enlarged view of a communication portion according to a modification of the third embodiment. FIG. 6 is a diagram illustrating the configuration of the fuel cell system according to the fourth embodiment. FIG. 7 is a diagram illustrating the configuration of the fuel cell according to the fourth embodiment. FIG. 8 is an enlarged view of the communication portion in FIG. FIG. 9 is a flowchart illustrating the operation of the fuel cell system according to the fourth embodiment. FIG. 10 is a diagram illustrating the configuration of the fuel cell according to the fifth embodiment. It is an enlarged view of the communication part in FIG. FIG. 12 is a diagram illustrating the configuration of the fuel cell according to Example 6. FIG. 13 is a diagram showing the configuration of the control bar in FIG. FIG. 14 is a diagram illustrating a configuration of a control bar according to a modification of the sixth embodiment. FIG. 15 is a diagram illustrating the configuration of the fuel cell according to the seventh embodiment. FIG. 16 is a diagram showing the configuration of the control bar in FIG.

  Embodiments according to the present invention will be described below with reference to the drawings.

  FIG. 1A is a schematic cross-sectional view of a fuel cell 10 according to the first embodiment. In FIG. 1A, a single cell is illustrated as the fuel cell 10. The fuel cell 10 includes a membrane-electrode assembly 30, a pair of gas diffusion layers (an anode gas diffusion layer 40 and a cathode gas diffusion layer 42) that sandwich the membrane-electrode assembly 30, and gas diffusion layers 40 and 42. A pair of separators (an anode separator 44 and a cathode separator 46). The membrane-electrode assembly 30 includes an electrolyte membrane 32, an anode catalyst layer 34, and a cathode catalyst layer 36. As the electrolyte membrane 32, for example, a solid polymer electrolyte membrane having proton conductivity (for example, a perfluorosulfonic acid membrane or the like) can be used.

  The anode catalyst layer 34 and the cathode catalyst layer 36 are arranged so as to sandwich the electrolyte membrane 32. The catalyst contained in the anode catalyst layer 34 promotes protonation of hydrogen, and the catalyst contained in the cathode catalyst layer 36 promotes the reaction between protons and oxygen. As a catalyst for the anode catalyst layer 34 and the cathode catalyst layer 36, for example, platinum can be used. For example, the anode catalyst layer 34 and the cathode catalyst layer 36 include platinum-supported carbon or the like.

  The anode gas diffusion layer 40 and the cathode gas diffusion layer 42 have conductivity and gas diffusibility. The anode gas diffusion layer 40 has a function of diffusing an anode gas containing hydrogen and supplying the anode gas to the anode catalyst layer 34. The cathode gas diffusion layer 42 has a function of diffusing a cathode gas containing oxygen and supplying it to the cathode catalyst layer 36. As the anode gas diffusion layer 40 and the cathode gas diffusion layer 42, for example, carbon fibers such as carbon paper and carbon cloth can be used.

  The anode separator 44 and the cathode separator 46 are disposed in contact with the anode gas diffusion layer 40 and the cathode gas diffusion layer 42, respectively. The anode separator 44 and the cathode separator 46 are formed with gas flow paths for supplying gas to the anode gas diffusion layer 40 and the cathode gas diffusion layer 42 as described later.

  FIG. 1B is a view of the cathode separator 46 as viewed from the membrane-electrode assembly 30 side. FIG.1 (c) is sectional drawing which looked at the cathode separator 46 from the AA line direction of FIG.1 (b). As shown in FIG. 1C, a groove-like recess is formed on the surface of the cathode separator 46 on the cathode gas diffusion layer 42 side. A region defined by the recess and the cathode gas diffusion layer 42 functions as a gas flow path for the cathode gas to flow. A supply manifold 50, a supply gas passage 52, a discharge manifold 60, and an exhaust gas passage 62, which will be described later, are formed by the groove-shaped recess.

  As shown in FIG. 1B, in this embodiment, a plurality of supply gas passages 52 (first gas passages) branching from the supply manifold 50 and a plurality of exhaust gas passages 62 branching from the discharge manifold 60 are used. Opposing comb gas channels are formed by alternately meshing with (second gas channels). The upstream end of the supply manifold 50 communicates with the gas supply port 54, and the downstream end of the discharge manifold 60 communicates with the gas discharge port 64.

  The supply gas channel 52 is a channel for supplying gas to the cathode gas diffusion layer 42, and its upstream end communicates with the supply manifold 50. In a typical comb-shaped flow path, the downstream end of the supply gas flow path 52 is often closed, but in the fuel cell 10 of this embodiment, the downstream end of the supply gas flow path 52 communicates with the drainage path 70. doing. The exhaust gas flow path 62 is a flow path for collecting and discharging the gas from the cathode gas diffusion layer 42, the upstream end thereof is closed, and the downstream end communicates with the discharge manifold 60. The supply gas passage 52 and the exhaust gas passage 62 are alternately formed with a predetermined interval.

  The drainage channel 70 is a channel for discharging water accumulated in the supply gas channel 52, and its upstream end communicates with the downstream end of the supply gas channel 52. In this embodiment, the downstream end of the drainage channel 70 communicates with the discharge manifold 60, but other configurations may be used as long as the purpose of drainage can be achieved. For example, the drainage channel 70 may be configured independently of the exhaust gas channel 62 and the exhaust manifold 60.

  A control valve 74 is provided in the communication portion 72 that leads from the supply gas passage 52 to the drainage passage 70. The control valve 74 functions as an increase / decrease unit that can increase / decrease the flow path cross-sectional area in the communication portion 72. Thereby, the channel area in the communication part 72 is adjusted, and the amount of water discharged from the supply gas channel 52 to the drainage channel 70 is adjusted. The control valve 74 can also close the communication part 72. Accordingly, the control valve 74 also functions as an opening / closing means for the communication portion 72.

  2 (a) and 2 (b) are enlarged views of the vicinity of the communication portion 72 in FIG. 1 (b). The control valve 74 is a bimetal in which a first metal plate 74a having a relatively high coefficient of thermal expansion and a second metal plate 74b having a coefficient of thermal expansion lower than that of the first metal plate 74a are bonded to each other. It is fixed to the wall surface at the boundary between the channel 52 and the drainage channel 70. The direction of the control valve 74 is adjusted so as to be inclined with respect to the gas flow direction, and the first metal plate 74a having a high coefficient of thermal expansion is disposed on the side close to the wall surface to which the control valve 74 is fixed. Yes.

  The control valve 74 bends due to the difference in thermal expansion coefficient between the two metal plates 74 a and 74 b in accordance with the temperature change in the communication portion 72, and increases or decreases the flow path cross-sectional area in the communication portion 72. When the temperature in the communication portion 72 is high, the expansion amount of the first metal plate 74a is larger than the expansion amount of the second metal plate 74b, so that the control valve 74 is indicated by the arrow A as shown in FIG. Turn in the direction. Thereby, the flow path cross-sectional area of the communication part 72 decreases. At this time, the cross-sectional area of the flow path may be 0 (a state where the inlet from the supply gas flow path 52 to the drain path 70 is completely closed). On the other hand, when the temperature at the communication portion 72 is low, the amount of contraction of the first metal plate 74a is larger than the amount of contraction of the second metal plate 74b, and therefore the control valve 74 is shown by an arrow as shown in FIG. Turn in the direction of B. Thereby, the flow path cross-sectional area of the communication part 72 increases.

  In the conventional fuel cell, there is a problem that the gas is insufficiently diffused due to the accumulation of water at the downstream end of the supply gas passage 52 (the portion where the dead end has been a dead end in the past). Further, in a fuel cell in which a drainage channel is provided at the downstream end of the supply gas channel, dry-up due to excessive drainage has been a problem.

  In the fuel cell 10 of the present embodiment, a drainage channel 70 that communicates with the downstream end of the supply gas channel 52 is provided, and a control valve 74 is provided at a communication portion 72 that communicates from the supply gas channel 52 to the drainage channel 70. Yes. As described above, the control valve 74 is set so that the flow path cross-sectional area can be adjusted according to the temperature of the communication portion 72. Thereby, the amount of drainage from the supply gas flow path 52 is appropriately controlled.

  Specifically, when the fuel cell 10 is in a high temperature state (high output), the evaporation of moisture is promoted, so that there is little residual liquid water at the downstream end of the supply gas flow path 52 (that is, much water has accumulated). Is not estimated). At this time, the control valve 74 decreases the flow path cross-sectional area of the communication part 72 (or completely closes the communication part 72), and decreases the amount of drainage from the supply gas flow path 52. Thereby, dry-up of the fuel cell 10 can be suppressed. Moreover, the downstream end of the supply gas flow path 52 becomes a dead end state or a state close thereto due to a reduction in the cross-sectional area of the communication portion 72. Thereby, the permeation of the gas from the supply gas flow path 52 to the cathode gas diffusion layer 42 is promoted, and the gas supply efficiency to the cathode gas diffusion layer 42 can be improved.

  On the other hand, when the fuel cell 10 is in a low temperature state (low output), the evaporation of water is not performed so much, so there is a large amount of residual liquid water at the downstream end of the supply gas passage 52 (that is, a large amount of water is accumulated). Estimated). At this time, the control valve 74 increases the cross-sectional area of the communication portion 72 and increases the amount of drainage from the supply gas flow path 52. Thereby, the fall of the gas diffusion capability by water staying in the downstream end of the supply gas flow path 52 can be suppressed.

  As described above, in the fuel cell 10 of the present embodiment, the amount of drainage from the supply gas passage 52 is adjusted based on the temperature due to the presence of the adjustment valve 74. Further, the temperature and relative humidity (water accumulation level) of the communication portion 72 are related to each other. Therefore, by using the control valve 74 made of bimetal, the control valve 74 can indirectly sense the amount of liquid water at the downstream end of the supply gas flow path 52 and autonomously adjust the amount of drainage. As a result, the water content of the fuel cell 10 can be appropriately controlled, and the power generation efficiency can be improved.

  In this embodiment and the following embodiments, the example in which the drainage channel 70 and the control valve 74 are provided in the cathode separator 46 has been described. However, the same configuration can be applied to the anode separator 44 to obtain the same effect. Is also possible. However, when a solid polymer is used for the electrolyte membrane 32, the generation and retention of water is particularly a problem in the cathode-side gas flow path. Therefore, the configurations of this embodiment and the following embodiments are particularly applicable to the cathode-side separator. Is preferred.

  The second embodiment is an example using a control valve having a different form from the first embodiment. The fuel cell 10 of the second embodiment is different from the first embodiment only in the shape of the control valve 74A, and the other configuration is common (see FIG. 1B). Therefore, the same code | symbol is attached | subjected to a common structure and detailed description is abbreviate | omitted.

  3A and 3B are enlarged views of the vicinity of the communication portion 72. FIG. FIG. 3A shows a closed valve state (a state where the flow passage cross-sectional area is small), and FIG. 3B shows a valve open state (a state where the flow passage cross-sectional area is large). The control valve 74A of this embodiment is made of a material having a relatively large thermal expansion coefficient (for example, resin, rubber, etc.). One end of the control valve 74A is fixed to the side wall of the communication portion 72, and is arranged in a direction substantially perpendicular to the gas flow direction.

  When the temperature of the communication portion 72 is high, the control valve 74A extends in a direction substantially perpendicular to the flow path, and decreases the flow path cross-sectional area. Thereby, the amount of drainage from the supply gas flow path 52 decreases. In FIG. 3A, the flow path is closed, but the flow path cross-sectional area may be reduced as the temperature rises. On the other hand, when the temperature of the communication portion 72 is low, the control valve 74A is reduced in a direction substantially perpendicular to the flow path, and the flow path cross-sectional area is increased. Thereby, the amount of drainage from the supply gas flow path 52 increases.

  As described above, even when the control valve 74A is used as the increasing / decreasing means, the channel cross-sectional area can be increased or decreased autonomously according to the temperature, as in the first embodiment. Thereby, the amount of drainage from the lower end of the supply gas channel can be appropriately adjusted, and the power generation efficiency can be improved.

  The third embodiment is an example using a control valve having a different form from the first and second embodiments. The fuel cell 10 of Example 3 is different from Example 1 only in the shape of the control valve 74B, and the other configuration is common (see FIG. 1B). Therefore, the same code | symbol is attached | subjected to a common structure and detailed description is abbreviate | omitted.

  4A and 4B are enlarged views of the vicinity of the communication portion 72. FIG. FIG. 4A shows a valve open state (a state where the channel cross-sectional area is large), and FIG. 4B shows a valve closed state (a state where the channel cross-sectional area is small). In this embodiment, one end of the drainage channel 70 communicates with the vicinity of the downstream end of the supply gas passage 52, and the other end communicates with the vicinity of the downstream end of the exhaust gas passage 62. In other words, the drainage channel 70 is formed in a direction (hereinafter referred to as the Y direction) that intersects the protruding direction of the supply gas flow path 52 from the supply manifold 50 (hereinafter referred to as the X direction).

  A dead end 73 is formed at the downstream end of the supply gas passage 52. The main surface of the control valve 74 </ b> B of the present embodiment is fixed to the wall surface of the dead end portion 73. The control valve 74B is made of a material having a relatively large coefficient of thermal expansion (for example, resin, rubber, etc.), and can be expanded and contracted in the X direction according to a temperature change.

  When the temperature of the communication part 72 is high, the control valve 74B extends in the X direction and closes the inlet of the drainage channel 70 (FIG. 4A). Thereby, the amount of drainage from the supply gas flow path 52 decreases. On the other hand, when the temperature of the communication portion 72 is low, the control valve 74B shrinks in the X direction and opens the inlet of the drainage channel 70 (FIG. 4B). Thereby, the amount of drainage from the supply gas flow path 52 increases.

  As described above, even when the drainage channel is provided in a direction crossing the protruding direction of the supply gas channel 52, the channel cross-sectional area can be increased or decreased autonomously in the same manner as in Examples 1-2.

  FIG. 5 is a diagram illustrating a modification of the third embodiment. In this modification, in addition to the first drainage path 70 communicating from the vicinity of the downstream end of the supply gas passage 52 to the vicinity of the downstream end of the exhaust gas passage 62, the exhaust gas flow from the vicinity of the upstream end of the supply gas passage 52. A second drainage channel 70 communicating with the vicinity of the upstream end of the channel 62 is formed. In addition, a first control valve 74B1 is provided in the dead end portion 73 of the supply gas flow path 52, and a second control valve 74B2 is provided in the dead end portion 73 of the exhaust gas flow path 62.

  According to this modification, the control valves 74B1 and 74B2 are deformed according to the temperature change in the same manner as in the third embodiment (FIGS. 4A to 4B), so that the supply gas flow path 52 and the exhaust gas flow path are changed. The amount of drainage to 62 is adjusted. Further, since the second drainage channel 70 is provided, the amount of drainage from the supply gas channel 52 is increased as compared with the third embodiment. Therefore, this modification is particularly suitable when a large amount of water tends to accumulate in the supply gas passage 52.

  The fourth embodiment is an example provided with a control mechanism for acquiring the water accumulation state at the downstream end of the supply gas flow path by some method and increasing / decreasing the cross-sectional area of the flow path at the communication portion based on the acquisition result.

  FIG. 6 is a diagram illustrating the configuration of the fuel cell system 100 according to the fourth embodiment. The fuel cell system 100 includes a fuel cell 10 configured by stacking a plurality of single cells. Connected to the fuel cell 10 are an anode gas supply means 12, a cathode gas supply means 13, a cooling water supply means 14, an ammeter 15 for measuring output, and a voltmeter 16. Further, a thermometer 18 for measuring the temperature of the cooling water is connected to the cooling water passage 17. Further, the fuel cell 10 of the present embodiment includes a drive unit 80 as an increasing / decreasing means for increasing / decreasing the flow path area in the communication unit 72 of the fuel cell 10 and a control unit 20 for controlling the drive unit 80. Yes. The control unit 20 is connected to the ammeter 15, the voltmeter 16, the thermometer 18, and the hygrometer 19, and acquires these output signals.

  FIG. 7 is a diagram showing the configuration of the single cell constituting the fuel cell 10 and its peripheral devices in the fuel cell system 100 of FIG. The drive unit 80 includes a plurality of pipes 81, and an elastic body 82 is attached to the tip of each pipe 81. The elastic body 82 is disposed so as to be located at a communication portion from the supply gas flow path 52 to the discharge manifold 60 (drainage path). The proximal end side of the pipe 81 is connected to the collecting pipe 83, and the collecting pipe 83 is connected to the pressure applying unit 84. The pressure in the collecting pipe 83 and the pipe 81 is changed by the pressure application unit 84, and the elastic body 82 attached to the tip of the pipe 81 is deformed along with the pressure change.

  8A and 8B are enlarged views of the vicinity of the communication portion 72. FIG. In the state of FIG. 8A, since the pressure applied from the pressure application unit 84 to the pipe 81 is small, the elastic body 82 contracts and the communication unit 72 from the supply gas flow path 52 to the discharge manifold 60 opens. For this reason, the amount of drainage from the downstream end of the supply gas passage 52 is relatively large.

  On the other hand, in the state of FIG. 8B, since the pressure applied from the pressure application unit 84 to the pipe 81 is large, the elastic body 82 expands and the communication unit 72 is closed. For this reason, the amount of drainage from the downstream end of the supply gas passage 52 is relatively small. As described above, the control unit 20 controls the pressure application unit 84 to change the flow path cross-sectional area of the communication part 72 and adjust the amount of drainage from the downstream end of the supply gas flow path 52.

  FIG. 9 is a flowchart illustrating the operation of the fuel cell system 100 according to the fourth embodiment. First, the control unit 20 acquires the relative humidity at the downstream end of the supply gas flow path 52 or a parameter capable of estimating the relative humidity (step S10). Next, the control unit 20 determines the relative humidity level (step S12). If the relative humidity is greater than the set value, the control unit 20 increases the amount of drainage (step S14). Specifically, the pressure in the pipe 81 is increased by the pressure application unit 84. If the relative humidity is smaller than the set value, the control unit 20 decreases the amount of drainage (step S16). Specifically, the pressure in the pipe 81 is decreased by the pressure application unit 84.

  The purpose in step S10 is to grasp the water accumulation at the downstream end (communication portion 72) of the supply gas passage 52. The degree of water accumulation can be obtained directly by measuring the relative humidity of the communicating portion 72. As a method of measuring the relative humidity of the communication portion 72, for example, a method of attaching the hygrometer 19 to the tip of the elastic body 82 can be considered.

  As described above, the amount of residual water in the communicating portion 72 can be estimated from the temperature of the communicating portion 72 (it is estimated that the temperature is lower than the set humidity when the temperature is high, and is higher than the set humidity when the temperature is low). The temperature of the communication part 72 can be calculated from, for example, the temperature of the cooling water (the temperature of the fuel cell 10) measured by the thermometer 18 of FIG. Further, for example, a thermocouple sensor can be provided at the tip of the elastic body 82 and the temperature of the communication portion 72 can be directly measured.

  Further, the humidity of the communication portion 72 can also be estimated from the output (load) of the fuel cell 10. The output of the fuel cell 10 refers to, for example, an output voltage measured by the ammeter 15 in FIG. 1 or an output current measured by the voltmeter 16. When the output of the fuel cell 10 is large, the temperature of the fuel cell 10 becomes high, so that the relative humidity in the communication portion 72 is estimated to be small. On the other hand, when the output of the fuel cell 10 is small, the temperature of the fuel cell 10 becomes low, so that the relative humidity in the communication portion 72 is estimated to be high.

  Moreover, the humidity of the communication part 72 can also be estimated from the gas flow rate. The gas flow rate can be measured, for example, by providing a gas flow meter at the gas outlet. When the gas flow rate is large, it is estimated that the relative humidity at the communication unit 72 is smaller than the set value, and when the gas flow rate is small, the relative humidity at the communication unit 72 is estimated to be larger than the set value.

  As described above, the control unit 20 can acquire the relative humidity in the communication unit 72 directly or indirectly by various methods. Therefore, in FIG. 6, the ammeter 15, the voltmeter 16, the thermometer 18, and the hygrometer 19 are not necessarily provided. When the relative humidity is high, the amount of drainage from the supply gas passage 52 is increased, and when the relative humidity is low, the amount of drainage is decreased (steps S14 and S16 in FIG. 9). As a result, the amount of drainage can be adjusted according to the amount of water accumulated at the downstream end of the supply gas passage 52, so that the amount of water in the fuel cell 10 can be maintained appropriately and the power generation efficiency can be improved.

  The fifth embodiment is an example in which a drive unit 80A having a configuration different from that of the fourth embodiment is used. FIG. 10 is a diagram illustrating the configuration of the fuel cell according to the fifth embodiment, and corresponds to FIG. 7 of the fourth embodiment. Common components are denoted by the same reference numerals, and detailed description thereof is omitted. In the present embodiment, the configuration of the drive unit 80 is different from that of the fourth embodiment.

  The drive unit 80 </ b> A of this embodiment has a plurality of rods 85, and a valve 86 is attached to the tip of each rod 85. The valve 86 is disposed so as to be located at a communication portion from the supply gas flow path 52 to the discharge manifold 60 (drainage path). The proximal end side of the rod 85 is connected to the collecting rod 87, and the collecting rod 87 is connected to the power unit 88. The power unit 88 causes the rod 85 to slide in the protruding direction (X direction) of the supply gas flow path 52, and the valve 86 also slides in the X direction along with the movement. Depending on the position of the valve 86, the flow path cross-sectional area in the communication portion 72 changes.

  FIGS. 11A and 11B are enlarged views of the vicinity of the communication portion 72. FIG. In the state of FIG. 11A, the rod 85 and the valve 86 slide in a direction away from the supply gas flow path 52, and the communication portion 72 from the supply gas flow path 52 to the discharge manifold 60 opens. For this reason, the amount of drainage from the downstream end of the supply gas passage 52 is relatively large. On the other hand, in the state of FIG. 11B, the rod 85 and the valve 86 slide in the direction approaching the supply gas flow path 52, and the communication portion 72 is closed. For this reason, the amount of drainage from the downstream end of the supply gas passage 52 is relatively small. As described above, the control unit 20 can control the power unit 88 to change the position of the valve 86 and change the flow path cross-sectional area of the communication unit 72.

  The operation of the fuel cell system 100 in the present embodiment is the same as that in the fourth embodiment (FIG. 9). As described above, even when the drive unit 80A including the rod 85, the valve 86, and the power unit 88 is used, the relative humidity at the downstream end of the supply gas flow path 52 (or a parameter capable of estimating the relative humidity) is used. The amount of drainage from the downstream end of the supply gas passage 52 can be adjusted.

  The sixth embodiment is an example in which an increase / decrease unit different from the first to fifth embodiments is provided.

  FIGS. 12A to 12B are diagrams illustrating the configuration of the fuel cell according to the sixth embodiment, and correspond to FIG. 1B of the first embodiment. In the present embodiment, a control bar 90 is disposed in the communication portion 72 as an increasing / decreasing means that can increase or decrease the flow path cross-sectional area in the communication portion 72. The supply gas passage 52 communicates with the drainage passage 70 via the control bar 90.

  FIG. 13 is a diagram showing a detailed configuration of the control bar 90. The control bar 90 has a first through hole 91 a for communicating the downstream end of the supply gas passage 52 to the drainage passage 70, and a second penetration for communicating the downstream end of the exhaust gas passage 62 to the discharge manifold 60. The holes 91b are alternately formed. The size of the first through hole 91a is preferably smaller than that of the second through hole 91b. In addition, the size of the second through hole 91b is large enough not to substantially affect the amount of gas and water discharged from the exhaust gas passage 62 to the exhaust manifold 60 by sliding of the control bar 90 described later. It is preferable. Specifically, the size of the second through hole 91 b is preferably larger than the flow path cross-sectional area of the exhaust gas flow path 62.

  A thermostat 92 is attached to one end of the control bar 90, and a water absorbent resin 93 is attached to the other end of the control bar 90. When the temperature of the fuel cell is high (humidity is low), the thermostat 92 expands and the water absorbent resin 93 contracts. As a result, the control bar 90 moves in the direction of arrow A (this position is defined as the first position). On the other hand, when the temperature of the fuel cell is low (humidity is high), the thermostat 92 contracts and the water absorbent resin 93 expands. Thereby, the control bar 90 moves in the direction of the arrow B (this position is set as the second position).

  In this embodiment, the initial position of the control bar 90 and the size of the through hole are determined so as to satisfy the following conditions. In other words, when the control bar 90 is in the first position, the first through hole 91a is located at a place away from the supply gas flow path 52, so that the communication portion 72 is closed (FIG. 12A). ). On the other hand, when the control bar 90 is in the second position, the first through hole 91a is positioned at the downstream end of the supply gas flow path 52 so that the communication portion 72 is opened (FIG. 12 (b)). .

  As described above, in this embodiment, when the fuel cell is in a high temperature and low humidity state, the amount of drainage is reduced by the control bar 90 being located at the first position. On the other hand, when the fuel cell is in a low temperature and low humidity state, the amount of drainage is increased by the control bar being positioned at the second position. As described above, even when the control bar is used as the increase / decrease means, the amount of drainage can be adjusted according to the relative humidity (and parameters related thereto) of the supply gas flow path 52.

  In the sixth embodiment, the position of the control bar 90 is autonomously changed by using the thermostat 92 and the water absorbent resin 93. However, the position of the control bar 90 may be changed by an external drive mechanism. .

  FIG. 14 is a diagram showing a configuration around the control bar 90 according to a modification. Unlike Example 6 (FIG. 13), a gear 95 connected to a stepping motor 94 is attached to one end of the control bar 90. The stepping motor 94 is electrically connected to the control unit 20 and is driven by a command from the control unit 20. The control part 20 is comprised so that the output from various sensors can be acquired similarly to FIG.

  According to said structure, when the control part 20 controls the stepping motor 94, the control bar 90 can be moved to the direction of an arrow, and the position of the 1st through-hole 91a can be changed. Thereby, the amount of drainage from the downstream end of the supply gas passage 52 can be accurately adjusted. The control unit 20 controls the amount of drainage based on the relative humidity at the downstream end of the supply gas passage 52 or a parameter related thereto. This point is the same as that of Example 3 (FIG. 9).

  Example 6 is an example in which the flow path is switched using a control bar.

  FIGS. 15A to 15B are diagrams showing a detailed configuration of the separator of the fuel cell according to the seventh embodiment, and correspond to FIG. 1B of the first embodiment. In the present embodiment, a first control bar 90a and a second control bar 90b are provided at the upstream end and the downstream end of the plurality of gas flow paths 53 between the supply manifold 50 and the discharge manifold 60, respectively. The upstream ends of the plurality of gas flow paths 53 communicate with the supply manifold 50 via the first control bar 90a. Further, the downstream ends of the plurality of gas flow paths 53 communicate with the discharge manifold 60 via the second control bar 90b. That is, in this embodiment, all the gas flow paths communicate with the supply manifold 50 and the discharge manifold 60, and this point is different from the first to sixth embodiments in which the upstream end of the exhaust gas flow path 62 is closed. Different.

  FIG. 16 is a diagram illustrating the configuration of the control bars (the first control bar 90a and the second control bar 90b). In the control bar 90, a plurality of through holes 91 having a cross-sectional area substantially equal to the cross-sectional area of the gas flow path 53 are formed at predetermined intervals.

  FIG. 15A shows a state where the first control bar 90a and the second control bar 90b are in the first position. At this time, a part of the plurality of gas flow paths (hereinafter referred to as the first gas flow path 53a) has an upstream end connected to the supply manifold 50 via the first control bar 90a and a downstream end connected to the second control. It is in a state of being blocked by the bar 90b. The remaining gas flow path (hereinafter referred to as the second gas flow path 53b) is closed at the upstream end by the first control bar 90a, and the downstream end is connected to the discharge manifold 60 via the second control bar 90b. It has become a state. That is, when the first control bar 90a and the second control bar 90b are in the first position, the first gas flow path 53a serves as the supply gas flow path 52 in the first to sixth embodiments, and the second gas flow path 53b. Serves as the exhaust gas flow path 62.

  FIG. 15B shows a state where the first control bar 90a and the second control bar 90b are in the second position. At this time, the upstream end of the first gas flow path 53a is blocked by the first control bar 90a, and the downstream end is connected to the discharge manifold 60 via the second control bar 90b. Further, the second gas flow path 53b is in a state in which its upstream end is connected to the supply manifold 50 via the first control bar 90a and its downstream end is closed by the second control bar 90b. That is, when the first control bar 90a and the second control bar 90b are in the second position, the first gas passage 53a serves as the exhaust gas passage 62, and the second gas passage 53b serves as the supply gas passage 52. To play a role.

  As described above, according to the fuel cell system 100 of the seventh embodiment, by changing the positions of the first control bar 90a and the second control bar 90b, a plurality of gases between the supply manifold 50 and the discharge manifold 60 can be obtained. The flow path 53 (the first gas flow path 53a and the second gas flow path 53b) can be used by switching to either the supply gas flow path 52 or the exhaust gas flow path 62. Thereby, for example, when water accumulates at the downstream end of the gas flow path 53 used as the supply gas flow path 52, the downstream end is changed by switching the supply gas flow path 52 so far to the exhaust gas flow path 62. It is opened and the accumulated water is drained. Thereby, the fall of the power generation efficiency by water stagnating in the downstream end of a supply gas flow path can be suppressed.

  The position control of the first control bar 90a and the second control bar 90b may be performed autonomously according to the environment as shown in FIGS. 12B to 12C, or as shown in FIG. It is good also as a structure controlled by the control part 20. FIG. In any method, the retention of water at the downstream end of the gas passage 53 used as the supply gas passage 52 can be suppressed, and the power generation efficiency can be improved.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

DESCRIPTION OF SYMBOLS 10 Fuel cell 20 Control part 30 Membrane-electrode assembly 50 Supply manifold 52 Supply gas flow path 60 Discharge manifold 62 Exhaust gas flow path 70 Drainage path 72 Communication part 74 Control valve 90 Control bar 100 Fuel cell system

Claims (4)

A membrane-electrode assembly;
A pair of gas diffusion layers sandwiching the membrane-electrode assembly;
A pair of separators sandwiching the pair of gas diffusion layers,
In the gas diffusion layer side surface of at least one of the pair of separators,
A groove-shaped first gas passage whose upstream end communicates with the supply manifold and whose downstream end communicates with the drainage channel;
An increasing / decreasing means arranged at a communicating portion from the first gas flow path to the drainage channel, and capable of increasing / decreasing a flow path cross-sectional area at the communicating section;
Is provided ,
In the gas diffusion layer side surface of the separator having the first gas flow path,
A fuel cell comprising a groove-shaped second gas flow path whose downstream end communicates with a discharge manifold and whose upstream end is a dead end . 2. The increase / decrease unit autonomously increases / decreases a flow path cross-sectional area based on a relative humidity at a downstream end of the first gas flow path or a parameter capable of estimating the relative humidity. A fuel cell according to claim 1. An acquisition means for acquiring a relative humidity at a downstream end of the first gas flow path, or a parameter capable of estimating the relative humidity;
Based on the relative humidity or the parameter acquired by the acquisition means, a control means for controlling increase / decrease of the channel cross-sectional area by the increase / decrease means;
The fuel cell according to claim 1, characterized in that it comprises a. The parameter is at least one of a temperature at the downstream end of the first gas flow path, a gas flow rate at a gas discharge port communicating with the downstream end of the discharge manifold, an output current of the fuel cell, and an output voltage of the fuel cell. the fuel cell according to claim 3, characterized in that.

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