JP6951045B2 - Fuel cell system - Google Patents

Description

The present invention relates to a fuel cell system.

In the separator, the cooling water flow path is connected to two inlets, one of the inlets of the cooling water flow path is located near the inlet of the oxidant gas flow path, and the outlet of the cooling water flow path is located near the outlet of the oxidant gas flow path. Fuel cells are known (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2008-176974

A fuel cell having a separator located near the oxidant gas discharge manifold and the fuel gas discharge manifold near the oxidant gas introduction manifold is known. In such a fuel cell, a part of the generated water moves from the region on the downstream side of the oxidant gas flow path to the region on the upstream side of the fuel gas flow path, and a part of the generated water moves to the upstream side of the oxidant gas flow path. By moving a part of the water contained in the fuel gas from the downstream side of the fuel gas flow path, the water generated by the power generated by the fuel cell circulates inside the fuel cell, and the inside of the fuel cell becomes dry as a whole. It is suppressed.

However, when the amount of power generated by the fuel cell increases, a large amount of dry fuel gas flows into the fuel gas flow path, so that the fuel gas flow path may be easily dried in the vicinity of the fuel gas introduction manifold. On the other hand, when the amount of power generated by the fuel cell decreases, the amount of water generated by the power generated by the fuel cell decreases, and the flow rate of fuel gas and oxidant gas in the fuel cell decreases, so that the amount of water circulating in the fuel cell decreases. Therefore, the entire fuel cell becomes easy to dry. At this time, the oxidant gas flow path is most likely to be dried near the introduction manifold of the oxidant gas into which the dry air flows. Therefore, in the fuel gas flow path, the vicinity of the fuel gas discharge manifold facing the vicinity of the oxidant gas introduction manifold is dried through the electrolyte membrane.

As described above, since the portion of the fuel cell that tends to dry differs depending on the amount of power generation, it is desired to suppress the drying of the portion of the fuel cell that is appropriate according to the amount of power generation. The point of suppressing drying is not disclosed.

Therefore, 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 system capable of suppressing drying of an appropriate fuel cell portion according to the amount of power generation.

The fuel cell system described in the present specification includes a fuel cell having a membrane electrode joint in which a power generation reaction of a fuel gas and an oxidizing agent gas is performed, a pair of separators sandwiching the membrane electrode joint, and the fuel cell. A first introduction hole into which the fuel gas is introduced is provided in the pair of separators, comprising a pressure regulating valve for adjusting the flow rate of the cooling refrigerant and a control unit for controlling the pressure regulating valve based on the amount of power generated by the fuel cell. The first discharge hole for discharging the fuel gas, the second introduction hole closer to the first discharge hole than the first introduction hole, and the second introduction hole into which the oxidant gas is introduced, and the first discharge hole. A second discharge hole near the first introduction hole and from which the oxidant gas is discharged, a third introduction hole and a fourth introduction hole into which the fuel is introduced, and a third discharge hole through which the fuel is discharged. Is provided, one of the pair of separators is provided with a fuel gas flow path through which the fuel gas flows from the first introduction hole to the first discharge hole, and the other of the pair of separators is provided with the second. An oxidant gas flow path through which the oxidant gas flows is provided from the introduction hole to the second discharge hole, and the third introduction hole and the fourth are on the back side of the fuel gas flow path or the oxidant gas flow path. A refrigerant flow path through which the fuel flows is provided from the introduction hole to the third discharge hole, and the third introduction hole is closer to the first introduction hole than the first discharge hole, and the second introduction hole is closer to the first introduction hole. Close to the 1 introduction hole, the 4th introduction hole is closer to the 2nd introduction hole than the 2nd discharge hole, and communicates with the upstream side of the fuel flow path from the 3rd introduction hole. The control unit is connected to the third introduction hole or the fourth introduction hole, and when the amount of power generated is equal to or higher than a predetermined threshold value, the control unit of the fuel cell introduced from the third introduction hole and the fourth introduction hole, respectively. The pressure regulating valve is controlled so that the ratio of the flow rate of the fuel introduced from the third introduction hole to the total flow rate is larger than when the amount of power generation is less than the predetermined threshold value.

According to the present invention, it is possible to suppress drying of an appropriate fuel cell portion according to the amount of power generation.

It is an exploded perspective view which shows an example of a fuel cell. It is sectional drawing of a part of a fuel cell. It is a top view which shows an example of a refrigerant flow path, a fuel gas flow path, and an oxidant gas flow path. It is a figure which shows an example of the distribution of relative humidity in a fuel gas flow path for each current density of a fuel cell. FIG. 5 is a plan view showing another example of a refrigerant flow path, a fuel gas flow path, and an oxidant gas flow path.

FIG. 1 is an exploded perspective view showing an example of a fuel cell. FIG. 1 shows a fuel cell 2 by a one-point perspective drawing method, and also shows an ECU (Electronic Control Unit) 1 and a pressure regulating valve 3. The ECU 1, the fuel cell 2, and the pressure regulating valve 3 are included in the fuel cell system. The fuel cell 1 is, for example, a solid polymer type, and is supplied with a fuel gas (for example, hydrogen) and an oxidant gas (for example, oxygen in the air), and generates power by a chemical reaction between the fuel gas and the oxidant gas.

The fuel cell 2 has a MEGA (Membrane-Electrode-Gas diffusion layer assembly) 20 laminated along the stacking direction, a resin sheet 21, an intermediate plate 22, and a pair of separators 23 and 24. Although the fuel cell 2 is described as one single cell in FIG. 1, it is actually configured by stacking a plurality of single cells in the stacking direction.

The resin sheet 21 has a rectangular outer shape as an example, and an opening 210 is provided in the central portion. The opening 210 is provided at a position corresponding to the MEGA 20, and the end portion of the MEGA 20 is adhered to the edge thereof.

The separators 23 and 24 are made of, for example, a metal plate and have a rectangular outer shape. The separators 23 and 24 are adhered to the resin sheet 21 with, for example, an adhesive. The separator 23 is arranged on the anode side of the MEGA 20, and the separator 24 is arranged on the cathode side of the MEGA 20. Therefore, the MEGA 20 is sandwiched between the separators 23 and 24.

An oxidant gas flow path 240 through which the oxidant gas flows is formed on the surface of the separator 24 facing the MEGA 20. The oxidant gas flow path 240 faces the surface of the MEGA 20 on the cathode side.

Further, a fuel gas flow path 230 through which the fuel gas flows is formed on the surface of the separator 23 facing the MEGA 20. The fuel gas flow path 230 faces the anode-side surface of the MEGA 20.

An intermediate plate 22 is arranged on the opposite side of the MEGA 20 with the separator 23 in between. The intermediate plate 22 is made of, for example, a metal plate and has a rectangular outer shape. A refrigerant flow path 220 through which a refrigerant (for example, cooling water) for cooling the fuel cell 2 flows is formed on the surface of the intermediate plate 22 opposite to the separator 23.

Further, the intermediate plate 22 may be arranged on the opposite side of the MEGA 20 with the separator 24 interposed therebetween. In this case, the refrigerant flow path 220 is formed on the surface of the intermediate plate 22 opposite to the separator 24. As described above, the refrigerant flow path 220 is provided on the back side of the fuel gas flow path 230 or the oxidant gas flow path 240. The refrigerant flow path 220 may be provided on the surface of the separator 23 on the opposite side of the fuel gas flow path 230 or on the surface of the separator 24 on the opposite side of the oxidant gas flow path 240, instead of the intermediate plate 22. ..

Further, on the resin sheet 21, the intermediate plates 22, and the separators 23 and 24, the fuel gas introduction manifold 51, the fuel gas discharge manifold 50, the oxidizer gas introduction manifold 41, the oxidizer gas discharge manifold 40, and the refrigerant introduction manifolds 61, 62 , And a refrigerant discharge manifold 60 is provided. The fuel gas introduction manifold 51, the fuel gas discharge manifold 50, the oxidant gas introduction manifold 41, the oxidant gas discharge manifold 40, the refrigerant introduction manifolds 61 and 62, and the refrigerant discharge manifold 60 are MEGA 20, a resin sheet 21, an intermediate plate 22, It is a through hole through which a fluid flows when the separators 23 and 24 are laminated.

The fuel gas introduction manifold 51 is an example of the first introduction hole, and is provided on one end side of the resin sheet 21, the intermediate plate 22, and the separators 23 and 24. The fuel gas discharge manifold 50 is an example of the first discharge hole, and is provided on the other end side of the resin sheet 21, the intermediate plate 22, and the separators 23 and 24. The fuel gas introduction manifold 51 and the fuel gas discharge manifold 50 communicate with the fuel gas flow path 230.

The fuel gas is introduced into the fuel cell 2 by the fuel gas introduction manifold 51, and flows into the fuel gas flow path 230 from the fuel gas introduction manifold 51. The fuel gas flows through the fuel gas flow path 230 from the fuel gas introduction manifold 51 to the fuel gas discharge manifold 50, as indicated by reference numeral Dh. The fuel gas flow path 230 is formed in a groove shape and has a serpentine shape (serpentine shape) as an example. The fuel gas flows out from the fuel gas flow path 230 to the fuel gas discharge manifold 50, and is discharged from the fuel cell 2 by the fuel gas discharge manifold 50.

The oxidant gas introduction manifold 41 is an example of the second introduction hole, and is provided on one end side of the resin sheet 21, the intermediate plate 22, and the separators 23 and 24. The oxidant gas discharge manifold 40 is an example of the second discharge hole, and is provided on the other end side of the resin sheet 21, the intermediate plate 22, and the separators 23 and 24. The oxidant gas introduction manifold 41 and the oxidant gas discharge manifold 40 communicate with the oxidant gas flow path 240.

The oxidant gas is introduced into the fuel cell 2 by the oxidant gas introduction manifold 41, and flows into the oxidant gas flow path 240 from the oxidant gas introduction manifold 41. The oxidant gas flows through the oxidant gas flow path 240 from the oxidant gas introduction manifold 41 to the oxidant gas discharge manifold 40, as indicated by reference numeral Da. The oxidant gas flow path 240 is formed in a groove shape and has a straight shape (straight shape) as an example. The oxidant gas flows out from the oxidant gas flow path 240 to the oxidant gas discharge manifold 40, and is discharged from the fuel cell 2 by the oxidant gas discharge manifold 40.

The refrigerant introduction manifold 61 is provided on one end side of the resin sheet 21, the intermediate plate 22, and the separators 23, 24, and the refrigerant introduction manifold 62 and the refrigerant discharge manifold 60 are the resin sheet 21, the intermediate plate 22, and the separators 23, 24. It is provided on the other end side of the. The refrigerant introduction manifolds 61 and 62 and the refrigerant discharge manifold 60 communicate with the refrigerant flow path 220. The refrigerant introduction manifold 62 communicates with the refrigerant introduction manifold 61 on the upstream side of the refrigerant flow path 220. The refrigerant introduction manifold 61 is an example of the third introduction hole, the refrigerant introduction manifold 62 is an example of the fourth introduction hole, and the refrigerant discharge manifold 60 is an example of the third discharge hole.

The refrigerant is introduced into the fuel cell 2 by the refrigerant introduction manifolds 61 and 62, and flows into the refrigerant flow path 220 from the refrigerant introduction manifolds 61 and 62. The oxidant gas flows through the refrigerant flow path 220 from the refrigerant introduction manifolds 61 and 62 to the refrigerant discharge manifold 60, as indicated by reference numeral Dc. The refrigerant flow path 220 is formed in a groove shape and has a substantially U-shape as an example. The refrigerant flows out from the refrigerant flow path 220 to the refrigerant discharge manifold 60, and is discharged from the fuel cell 2 by the refrigerant discharge manifold 60.

FIG. 2 is a cross-sectional view of a part of the fuel cell 2. More specifically, FIG. 2 shows a cross section of the MEGA 20 and the separators 23 and 24 along the stacking direction in reference numeral P1 of FIG.

The MEGA 20 includes a gas diffusion layer (GDL) 203 and 204 and a MEA (Membrane Electrode Assembly) 205. The MEA 205 is sandwiched between the gas diffusion layers 203 and 204, and has an electrolyte membrane 200, an anode catalyst layer 201, and a cathode catalyst layer 202.

The electrolyte membrane 200 is composed of, for example, an ion exchange resin membrane that exhibits good proton conductivity in a wet state. Examples of such an ion exchange resin film include fluororesin-based films having a sulfonic acid group as an ion exchange group, such as Nafion (registered trademark).

The anode catalyst layer 201 and the cathode catalyst layer 202 are electrodes, respectively, and are formed as a gas-diffusible porous layer containing catalyst-supporting conductive particles and a proton-conducting electrolyte. For example, the anode catalyst layer 201 and the cathode catalyst layer 202 are formed as a dry coating film of a catalyst ink which is a dispersion solution containing platinum-supported carbon and a proton conductive electrolyte.

Fuel gas (see reference numeral Dh) flowing through the fuel gas flow path 230 of the separator 23 is supplied to the anode catalyst layer 201 via one of the gas diffusion layers 203. The oxidant gas (see reference numeral Da) flowing through the oxidant gas flow path 240 of the separator 24 is supplied to the cathode catalyst layer 202 via the other gas diffusion layer 204.

The gas diffusion layers 203 and 204 are formed by laminating a water-repellent microporous layer on a base material such as carbon paper. The microporous layer is formed by containing, for example, a water-repellent resin such as PTFE (Polytetrafluoroethylene) and a conductive material such as carbon black. In MEA205, a power generation reaction of an oxidant gas and a fuel gas is carried out.

Further, the refrigerant flows along the refrigerant flow path 220 through the intermediate plate 22 (not shown) adjacent to the separator 23 (see reference numeral Dc). As a result, the MEA 205 heated by the power generation reaction is cooled.

Referring to FIG. 1 again, the refrigerant is supplied to the fuel cell 2 from a heat exchanger (not shown) via the supply path 30. The supply path 30 branches into two branch paths 31 and 32, one branch path 31 is connected to the refrigerant introduction manifold 61, and the other branch path 32 is connected to the refrigerant introduction manifold 62. As a result, the refrigerant introduction manifold 61 introduces the refrigerant from one branch path 31, and the refrigerant introduction manifold 62 introduces the refrigerant from the other branch path 32.

The pressure regulating valve 3 is connected to the refrigerant introduction manifold 61 and adjusts the flow rates F1 and F2 of the refrigerant. More specifically, the pressure regulating valve 3 is provided on the branch path 31, and when the opening degree thereof increases, the flow rate F1 of the refrigerant introduced from the refrigerant introduction manifold 61 increases, and the pressure regulating valve 3 is introduced from the refrigerant introduction manifold 62. The flow rate F2 of the refrigerant decreases. Further, when the opening degree of the pressure regulating valve 3 decreases, the flow rate F1 of the refrigerant introduced from the refrigerant introduction manifold 61 decreases, and the flow rate F2 of the refrigerant introduced from the refrigerant introduction manifold 62 increases. The pressure regulating valve 3 may be connected to the refrigerant introduction manifold 62.

The ECU 1 is an example of a control unit, and controls the pressure regulating valve 3 based on the amount of power generated by the fuel cell 2. More specifically, the ECU 1 detects the amount of power generation from the parameters related to the operating state of the fuel cell 2. The parameters include the required output of the fuel cell 2 (for example, the opening degree of the accelerator pedal), the output current, the output voltage, the output power, the temperature, the humidity, and the supply amounts of the fuel gas and the oxidant gas.

Based on the amount of power generation, the ECU 1 generates, for example, a control signal S indicating a control target value of the opening degree of the pressure regulating valve 3 and outputs the control signal S to the pressure regulating valve 3. The pressure regulating valve 3 sets the opening degree according to the control signal S. As a result, the ECU 1 has a ratio (F1 /) of the flow rate F1 of the refrigerant introduced from the refrigerant introduction manifold 61 to the total flow rate (F1 + F2) of the refrigerant introduced from each of the refrigerant introduction manifolds 61 and 62 based on the amount of power generation. (F1 + F2)) is controlled. Therefore, in the fuel cell 2, drying of an appropriate portion according to the amount of power generation is suppressed.

FIG. 3 is a plan view showing an example of the refrigerant flow path 220, the fuel gas flow path 230, and the oxidant gas flow path 240. In FIG. 3, the same reference numerals are given to the configurations common to those in FIG. 1, and the description thereof will be omitted.

On the upper part of the paper surface of FIG. 3, a plan view of the forming surface of the refrigerant flow path 220 in the intermediate plate 22 when viewed from the front in the stacking direction is described. In the center of the paper surface of FIG. 3, a plan view of the separator 23 on the side opposite to the formation surface of the fuel gas flow path 230 when viewed from the front in the stacking direction is described. That is, in the center of the paper in FIG. 3, a state in which the fuel gas flow path 230 is viewed from the back side is shown. A plan view of the forming surface of the oxidant gas flow path 240 in the separator 24 when viewed from the front in the stacking direction is described in the lower part of the paper surface of FIG.

As indicated by the reference numeral Dh, the fuel gas flows into the fuel gas flow path 230 from the fuel gas introduction manifold 51, flows through the serpentine-shaped fuel gas flow path 230, and is discharged from the fuel gas discharge manifold 50. Further, as indicated by reference numeral Da, the oxidant gas flows into the oxidant gas flow path 240 from the oxidant gas introduction manifold 41, flows through the straight-shaped oxidant gas flow path 240, and the oxidant gas discharge manifold 40. Is discharged from.

The oxidant gas introduction manifold 41 and the oxidant gas discharge manifold 40 are provided on two opposite sides of the separators 23 and 24 and the intermediate plate 22, respectively. Further, the fuel gas introduction manifold 51 is provided at one end of the separators 23 and 24 and the intermediate plate 22 at a position closer to the oxidant gas discharge manifold 40 than the oxidant gas introduction manifold 41. The fuel gas discharge manifold 50 is provided at the other ends of the separators 23 and 24 and the intermediate plate 22 at positions closer to the oxidant gas introduction manifold 41 than the oxidant gas discharge manifold 40.

That is, in the separators 23 and 24, the fuel gas introduction manifold 51, which is the inlet of the fuel gas flow path 230, is located near the oxidant gas discharge manifold 40, which is the outlet of the oxidant gas flow path 240. Further, the fuel gas discharge manifold 50, which is the outlet of the fuel gas flow path 230, is located near the oxidant gas introduction manifold 41, which is the inlet of the oxidant gas flow path 240.

Therefore, a part of the generated water moves from the region on the downstream side of the oxidant gas flow path 240 to the region on the upstream side of the fuel gas flow path 230. Further, a part of the water contained in the fuel gas moves to the upstream side of the oxidant gas flow path 240 from the downstream side of the fuel gas flow path 230, so that the water generated by the power generation of the fuel cell 2 is generated by the fuel cell. It circulates inside 2 and the drying is suppressed as a whole.

However, when the amount of power generated by the fuel cell 2 increases, a large amount of dried fuel gas flows into the fuel gas flow path 230, so that the fuel gas flow path 230 may be easily dried in the vicinity of the fuel gas introduction manifold 51. On the other hand, when the amount of power generated by the fuel cell 2 decreases, the amount of water generated by the power generated by the fuel cell 2 decreases, and the flow rates of the fuel gas and the oxidant gas in the fuel cell 2 decrease, so that the water in the fuel cell 2 circulates. Since the amount is reduced, the entire fuel cell 2 becomes easy to dry. At this time, the oxidant gas flow path 240 is most likely to be dried in the vicinity of the oxidant gas introduction manifold 41 into which the dry air flows. Therefore, in the fuel gas flow path, the vicinity of the fuel gas discharge manifold 50 facing the vicinity of the oxidant gas introduction manifold 41 is dried through the electrolyte membrane 200.

FIG. 4 is a diagram showing an example of the distribution of relative humidity in the fuel gas flow path 230 for each current density of the fuel cell 2. In FIG. 4, the vertical axis indicates the relative humidity [% RH], and the horizontal axis indicates the position in the fuel gas flow path 230. Here, the left end of the horizontal axis corresponds to the fuel gas inlet, and the right end of the horizontal axis corresponds to the fuel gas outlet. Examples of current densities include 1.1 [A / cm ² ], 1.7 [A / cm ² ], and 2.4 [A / cm ² ].

As indicated by reference numerals P2 and P3, in the fuel gas flow path 230, the vicinity of the inlet and the vicinity of the outlet are likely to dry. Near the inlet of the fuel gas flow path 230 ^{, the relative humidity is lowest when the current density is 2.4 [A / cm 2} ], and near the outlet of the fuel gas flow path 230, the current density is 1.1 [A / cm 2]. / Cm ² ] has the lowest relative humidity.

That is, the larger the amount of power generated by the fuel cell 2 is, the easier it is to dry near the inlet of the fuel gas flow path 230, and the smaller the amount of power generated by the fuel cell 2 is, the easier it is to dry near the outlet of the fuel gas flow path 230. Therefore, when the amount of power generated by the fuel cell 2 increases, the vicinity of the inlet of the fuel gas flow path 230 tends to dry, and when the amount of power generated by the fuel cell 2 decreases, the vicinity of the inlet of the oxidant gas flow path 240 tends to dry. Become.

Therefore, as shown in FIG. 3, the refrigerant introduction manifold 61 is provided at a position closer to the fuel gas introduction manifold 51 than the fuel gas discharge manifold 50 and closer to the fuel gas introduction manifold 51 than the oxidant gas introduction manifold 41. The refrigerant introduction manifold 62 is provided at a position closer to the oxidant gas introduction manifold 41 than the oxidant gas discharge manifold 40. Therefore, the refrigerant from the refrigerant-introduced manifold 61 cools the vicinity of the fuel gas-introduced manifold 51 in the fuel gas flow path 230 best, and suppresses its drying. Further, the refrigerant from the refrigerant-introduced manifold 62 cools the vicinity of the oxidant gas-introduced manifold 41 of the oxidant gas flow path 240 best, and suppresses its drying.

More specifically, the refrigerant introduction manifold 61 is adjacent to the fuel gas introduction manifold 51 at one end of the separators 23 and 24 and the intermediate plate 22. Further, the refrigerant introduction manifold 62 is adjacent to the fuel gas discharge manifold 50 at the other ends of the separators 23 and 24 and the intermediate plate 22. Further, the refrigerant discharge manifold 60 is adjacent to the refrigerant introduction manifold 62.

The refrigerant from the refrigerant introduction manifold 61 flows on the downstream side of the refrigerant flow path 220 and is discharged from the refrigerant discharge manifold 60, as indicated by reference numeral Dc1. Further, as shown by reference numeral Dc2, the refrigerant from the refrigerant introduction manifold 62 flows on the upstream side of the refrigerant flow path 220, then turns back and joins the refrigerant from the refrigerant introduction manifold 61, and is downstream of the refrigerant flow path 220. It flows to the side and is discharged from the refrigerant discharge manifold 60.

Here, the upstream side of the refrigerant flow path 220 overlaps the downstream side of the fuel gas flow path 230 and the upstream side of the oxidant gas flow path 240, and the downstream side of the refrigerant flow path 220 is the upstream side of the fuel gas flow path 230. And the downstream side of the oxidant gas flow path 240.

Therefore, the refrigerant from the refrigerant introduction manifold 62 cools the fuel gas flow path 230 and the oxidant gas flow path 240 as a whole. In particular, the vicinity of the fuel gas discharge manifold 50 close to the refrigerant-introduced manifold 62 and the vicinity of the oxidant gas-introduced manifold 41 are cooled most, so that drying is effectively suppressed.

On the other hand, the refrigerant from the refrigerant introduction manifold 61 cools the upstream side of the fuel gas flow path 230 and the downstream side of the oxidant gas flow path 240. In particular, the vicinity of the fuel gas introduction manifold 51 close to the refrigerant introduction manifold 61 is cooled most, so that drying is effectively suppressed.

The ECU 1 controls the pressure regulating valve 3 according to the amount of power generation to adjust the balance of the flow rates F1 and F2 of the refrigerant flowing into the refrigerant flow path 220 from the respective refrigerant introduction manifolds 61 and 62, and is appropriate according to the amount of power generation. Suppresses drying of various parts. For example, the ECU 1 adjusts so that when the power generation amount of the fuel cell 2 is equal to or more than a predetermined threshold value, the ratio of the flow rate F1 to the total of the flow rates F1 and F2 is larger than when the power generation amount is less than the predetermined threshold value. The pressure valve 3 is controlled.

Therefore, when the amount of power generation is less than the threshold value, drying in the vicinity of the oxidant gas introduction manifold 41 is suppressed, but when the amount of power generation increases and exceeds the threshold value, drying in the vicinity of the fuel gas introduction manifold 51 is suppressed. .. Therefore, according to the fuel cell system of the present embodiment, it is possible to suppress drying of an appropriate portion of the fuel cell 2 according to the amount of power generation. The threshold value is preset to an appropriate value according to the design of the fuel cell 2.

For example, when the amount of power generated is less than a predetermined threshold value, the ECU 1 sets the ratio of the flow rate F2 of the refrigerant from the refrigerant introduction manifold 62 to the total flow rate (F1 + F2) to 100 (%), and sets the ratio of the flow rate of the refrigerant from the refrigerant introduction manifold 61 to 100 (%). The ratio of F1 to the total flow rate (F1 + F2) is 0 (%). In this case, drying of the vicinity of the oxidant gas introduction manifold 41 in the oxidant gas flow path 240 is preferably suppressed.

Further, when the amount of power generation is equal to or higher than a predetermined threshold value, the ECU 1 sets the ratio of the flow rate F2 of the refrigerant from the refrigerant introduction manifold 62 to the total flow rate (F1 + F2) to 50 (%), and sets the flow rate of the refrigerant from the refrigerant introduction manifold 61 to 50 (%). The ratio of F1 to the total flow rate (F1 + F2) is 50 (%). In this case, drying of the fuel gas flow path 230 in the vicinity of the fuel gas introduction manifold 51 is preferably suppressed. As a result, deterioration of the power generation performance of the fuel cell 2 due to drying is suppressed.

Further, since the temperature of the fuel cell 2 becomes low when the amount of power generation is small, if the vicinity of the fuel gas introduction manifold 51 is excessively cooled, flooding may occur due to condensation of water vapor in the fuel gas flow path 230. .. However, when the power generation amount is less than a predetermined threshold value by the above operation, the ECU 1 sets the ratio of the refrigerant flow rate F1 from the refrigerant introduction manifold 61 to the total flow rate (F1 + F2) of the refrigerant flow rate F1 to the total flow rate (F1 + F2). In order to make it smaller than the case, it is possible to appropriately suppress the cooling in the vicinity of the fuel gas introduction manifold 51 when the amount of power generation is small. As a result, deterioration of the power generation performance of the fuel cell 2 due to flooding is also suppressed.

Further, in this example, the oxidant gas flow path 240 has a straight shape, but is not limited to this, and may have a serpentine shape as in the following example.

FIG. 5 is a plan view showing another example of the refrigerant flow path 220a, the fuel gas flow path 230a, and the oxidant gas flow path 240a. In FIG. 5, the same reference numerals are given to the configurations common to those in FIG. 3, and the description thereof will be omitted.

In this example, the oxidant gas flow path 240a has a serpentine shape, unlike FIG. 4. The oxidant gas introduction manifold 41a and the oxidant gas discharge manifold 40a communicate with the oxidant gas flow path 240a. The oxidant gas from the oxidant gas introduction manifold 41a flows through the oxidant gas flow path 240a and is discharged from the oxidant gas discharge manifold 40a, as indicated by reference numeral Da. The oxidant gas introduction manifold 41a is an example of the second introduction hole, and the oxidant gas discharge manifold 40a is an example of the second discharge hole.

Further, the fuel gas flow path 230a communicates with the fuel gas introduction manifold 51a and the fuel gas discharge manifold 50a, and has a serpentine shape. The fuel gas from the fuel gas introduction manifold 51a flows through the fuel gas flow path 230 and is discharged from the fuel gas discharge manifold 50a. The fuel gas introduction manifold 51a is an example of the first introduction hole, and the fuel gas discharge manifold 50a is an example of the first discharge hole.

The refrigerant flow path 220a communicates with the refrigerant introduction manifolds 61a and 62a and the refrigerant discharge manifold 60a, and has a U-shape. The refrigerant introduction manifold 62a communicates with the refrigerant introduction manifold 61a on the upstream side in the refrigerant flow path 220a. The refrigerants from the refrigerant introduction manifolds 61a and 62a merge in the refrigerant flow path 220a and are discharged from the refrigerant discharge manifold 60a, as indicated by reference numerals Dc1 and Dc2. The refrigerant introduction manifold 61a is an example of the third introduction hole, and the refrigerant introduction manifold 62a is an example of the fourth introduction hole.

The oxidant gas discharge manifold 40a, the fuel gas introduction manifold 51a, and the refrigerant introduction manifold 61a are provided at one ends of the intermediate plate 22 and the separators 23 and 24. Further, the oxidant gas introduction manifold 41a, the fuel gas discharge manifold 50a, the refrigerant introduction manifold 62a, and the refrigerant discharge manifold 60a are provided on the other ends of the intermediate plate 22 and the separators 23 and 24.

Therefore, the oxidant gas introduction manifold 41a is closer to the fuel gas discharge manifold 50a than the fuel gas introduction manifold 51a, and the oxidant gas discharge manifold 40a is closer to the fuel gas introduction manifold 51a than the fuel gas discharge manifold 50a. Further, the refrigerant introduction manifold 61a is closer to the fuel gas introduction manifold 51a than the fuel gas discharge manifold 50a, and the refrigerant introduction manifold 62a is closer to the oxidizer gas introduction manifold 41a than the oxidizer gas discharge manifold 40a.

Therefore, also in this example, by controlling the pressure regulating valve 3 as described above, the ECU 1 can obtain the same effects as those described above.

The embodiments described above are examples of preferred embodiments of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.

1 ECU (control unit)
2 Fuel cell 3 Pressure regulating valve 22 Intermediate plate 23,24 Separator 40, 40a Oxidizing agent gas discharge manifold (second discharge hole)
41,41a Oxidizing agent gas introduction manifold (second introduction hole)
50, 50a Fuel gas discharge manifold (first discharge hole)
51,51a Fuel gas introduction manifold (first introduction hole)
60,60a Refrigerant discharge manifold (third discharge hole)
61,61a Refrigerant introduction manifold (third introduction hole)
62,62a Refrigerant introduction manifold (4th introduction hole)
205 MEA
220 Refrigerant flow path 230 Fuel gas flow path 240 Oxidizing agent gas flow path

Claims (1)

A fuel cell having a membrane electrode assembly in which a power generation reaction of a fuel gas and an oxidant gas is performed, and a pair of separators sandwiching the membrane electrode assembly.
A pressure regulating valve that adjusts the flow rate of the refrigerant that cools the fuel cell,
A control unit that controls the pressure regulating valve based on the amount of power generated by the fuel cell is provided.
The pair of separators
The first introduction hole into which the fuel gas is introduced and
The first discharge hole from which the fuel gas is discharged and
The second introduction hole, which is closer to the first discharge hole than the first introduction hole and into which the oxidant gas is introduced,
A second discharge hole closer to the first introduction hole than the first discharge hole and from which the oxidant gas is discharged,
The third introduction hole and the fourth introduction hole into which the refrigerant is introduced, respectively,
A third discharge hole for discharging the refrigerant is provided.
One of the pair of separators is provided with a fuel gas flow path through which the fuel gas flows from the first introduction hole to the first discharge hole.
On the other side of the pair of separators, an oxidant gas flow path through which the oxidant gas flows from the second introduction hole to the second discharge hole is provided.
On the back side of the fuel gas flow path or the oxidant gas flow path, a refrigerant flow path through which the refrigerant flows from the third introduction hole and the fourth introduction hole to the third discharge hole is provided.
The third introduction hole is closer to the first introduction hole than the first discharge hole, and closer to the first introduction hole than the second introduction hole.
The fourth introduction hole is closer to the second introduction hole than the second discharge hole, and communicates with the upstream side of the refrigerant flow path from the third introduction hole.
The pressure regulating valve is connected to the third introduction hole or the fourth introduction hole.
When the amount of power generation is equal to or higher than a predetermined threshold value, the control unit is introduced from the third introduction hole with respect to the total flow rate of the refrigerant introduced from the third introduction hole and the fourth introduction hole, respectively. The pressure regulating valve is controlled so that the ratio of the flow rates of the refrigerant is larger than that when the amount of power generation is less than the predetermined threshold value.
Fuel cell system.

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