JP2007103203A - Fuel cell system - Google Patents

Abstract

Fluid flow that can suppress backflow of supply gas at the time of start-up, purging, low load power generation, etc. of a fuel cell and is provided in an off-gas circulation path to suppress backflow of supply gas Provided is a fuel cell system in which a limiting member can be prevented from freezing at a low temperature.
SOLUTION: A fuel cell 2, a gas supply passage 22 through which a supply gas supplied to the fuel cell 2 is circulated, and an off gas circulation passage 23 through which off gas discharged from the fuel cell 2 is circulated and supplied to the fuel cell 2 again. And an ejector 24 that mixes the supply gas and the off-gas, and is provided in the off-gas circulation path 23, and the gas that flows through the off-gas circulation path 23 is supplied to the gas supply path 22 and the off-gas circulation path 23. The fuel cell system 1 includes a fluid passage restriction member 40 that has a flow passage 44 that can flow in the forward direction and the reverse direction, and that has a resistance to the forward flow that is smaller than a resistance to the reverse flow. is there.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell system, and includes an ejector that mixes a supply gas to a fuel cell and an off gas supplied from an off gas circulation path, and prevents fluid from flowing back into the off gas circulation path. The present invention relates to a fuel cell system including a limiting member.

  Conventionally, an anode and a cathode are provided on both sides of an electrolyte membrane, a fuel gas (for example, a gas containing hydrogen) is supplied to the anode, and an oxidizing gas (for example, a gas containing oxygen, usually air) is supplied to the cathode. Fuel cells that generate electric power through electrochemical reactions using these gases have been used. In the fuel cell system including such a fuel cell, not all of the fuel gas supplied to the fuel cell is used for the electrochemical reaction, and the fuel off-gas discharged from the fuel cell is unreacted. Contains fuel gas. Therefore, for the purpose of improving fuel efficiency, the fuel off-gas is collected, merged with the fuel gas supply path via the fuel off-gas circulation path, mixed with fresh fuel gas, and supplied to the fuel cell again.

  Some of such fuel cell systems circulate the fuel off-gas with an ejector. However, for the purpose of suppressing the back-flow of the fuel off-gas at the time of starting the fuel cell, during low-load power generation, or when discharging the fuel off-gas. In addition, a check valve (check valve) is provided in the fuel off-gas circulation path. (For example, refer to Patent Document 1).

In addition, a fuel cell system is also introduced in which a backflow prevention means (check valve) is provided in a bypass path branched from the fuel offgas circulation path and the opening and closing of the backflow prevention means is controlled. (For example, refer to Patent Document 2).
JP 2003-203661 A JP 2004-152529 A JP 2005-16412 A JP 2002-313289 A JP 2004-162878 A

  However, the backflow prevention valve (check valve) described in Patent Document 1 has a large contact area (seal area) between the valve body and the valve seat. There is room for. Further, as described in Patent Document 2, when the opening / closing of the backflow prevention means (check valve) is controlled, the configuration becomes complicated.

  The present invention has been made in view of such circumstances, and it is possible to prevent the supply gas from flowing backward at the start of the fuel cell, at the time of purging, at the time of low load power generation, and the like and provided in the off-gas circulation path. Another object of the present invention is to provide a fuel cell system in which the fluid flow restriction member that suppresses the backflow of the supply gas can suppress freezing at low temperatures.

  In order to achieve this object, the present invention provides a fuel cell, a gas supply path for distributing a supply gas supplied to the fuel cell, and an off-gas discharged from the fuel cell for supply to the fuel cell again. A fuel cell system comprising: an off-gas circulation path; and an ejector that is disposed at a junction of the gas supply path and the off-gas circulation path and that mixes the supply gas and the off-gas, wherein the off-gas circulation path A fluid passage that is capable of flowing gas flowing through the off-gas circulation path in the forward direction and the reverse direction, and has a resistance to the forward flow that is smaller than a resistance to the reverse flow. A fuel cell system provided with a limiting member is provided.

  In the fuel cell system having this configuration, a fluid flow restricting member having a resistance to a forward flow of gas flowing through the off-gas circulation path is smaller than a resistance to a reverse flow of the gas. Therefore, the supply gas and off gas can be prevented from flowing back through the off gas circulation path. Further, since the fluid flow restriction member circulates the gas through the flow passage, the gas flow is not completely sealed, so that the pressure loss with respect to the forward flow can be reduced. Freezing of the flow restriction member can be suppressed.

  The fluid flow restriction member may include a valve body and a valve seat, and may have a configuration in which the flow passage is formed in the valve body. By comprising in this way, the contact area of a valve body and a valve seat can be made small by presence of the said flow path. Therefore, it is possible to further prevent the fluid flow restriction member from freezing.

  The valve body can be formed of a material having higher water repellency than an inner wall that defines the off-gas circulation path. By comprising in this way, adhesion of the water droplet to a valve body can be suppressed, and also freezing can be suppressed.

  Further, the valve body can be arranged such that the fluid flow restriction member is in an open state (normally open) at a normal time. Thus, by keeping the fluid flow restriction member in an open state at normal times, in addition to the advantages, the pressure loss can be further reduced.

  The valve body may be formed with a plurality of abutting portions that define a part of the flow passage and abut against the valve seat. By comprising in this way, since the contact area of a contact part and a valve seat becomes a contact area of a valve body and a valve seat, the said contact area can be made small. Therefore, it is possible to further prevent the fluid flow restriction member from freezing.

  Further, the fluid flow restriction member according to the present invention can be configured to be deformable according to the direction of the gas flowing through the off-gas circulation path. By comprising in this way, since the fluid distribution control member does not have a drive part like the conventional check valve, for example, it can suppress freezing.

  The fluid flow restriction member may include a configuration in which an upstream outer shape of the forward flow is larger than a downstream outer shape. That is, the outer shape of the cross section along the gas flow direction of the fluid flow restriction member can have a configuration in which the upstream side of the forward flow is long and the downstream side is short trapezoidal. By comprising in this way, the resistance with respect to the forward flow of gas can be made still smaller efficiently than the resistance with respect to the reverse flow.

  Further, as an embodiment in which the fluid flow restriction member can be deformed according to the direction of the gas flowing through the off-gas circulation path, the fluid flow restriction member is formed according to the forward flow. The opening area of the flow passage can be expanded and the opening area of the flow passage can be reduced according to the flow in the reverse direction.

  In addition, as an embodiment of the configuration in which the opening area of the flow passage is expanded or reduced in accordance with the direction of the gas flowing through the off-gas circulation path, the flow passage is defined by an opening / closing member. The opening / closing member is rotated in the opening direction in accordance with the forward flow to expand the opening area of the flow passage, and is rotated in the closing direction in response to the reverse flow. The opening area of the road can be reduced.

  Furthermore, the opening / closing member is configured to rotate with one end as a fulcrum and the other end as a free end, and is inclined toward the closing direction with respect to the direction of gas flowing through the off-gas circulation path. You can also. With this configuration, when the gas flows in the reverse direction, it is easy to press the opening / closing member with the gas, and the opening / closing member can be further easily rotated in the closing direction.

  The fuel cell system according to the present invention can also include a plurality of the flow passages.

  In the fuel cell system according to the present invention, the off-gas circulation path has a flow path through which the gas flowing through the off-gas circulation path can flow in the forward direction and the reverse direction, and the resistance to the forward flow of the gas is Since a configuration in which a fluid flow restriction member having a resistance smaller than the resistance to the reverse flow of the gas is provided, it is possible to suppress the supply gas and the off gas from flowing back through the off gas circulation path. Moreover, the pressure loss with respect to the forward flow can be reduced, and the fluid flow restriction member can be further prevented from freezing. As a result, it is possible to provide a fuel cell system that is highly reliable and can efficiently generate power.

Next, a fuel cell system according to a preferred embodiment of the present invention will be described with reference to the drawings. In addition, embodiment described below is the illustration for demonstrating this invention, and this invention is not limited only to these Examples. Therefore, the present invention can be implemented in various forms without departing from the gist thereof. In the present embodiment, the upstream side when the gas passing through the off-gas circulation path of the fuel cell system flows in the forward direction is described as “upstream”, and the downstream side is described as “downstream”.
(Embodiment 1)

  1 is a diagram showing a main part of a fuel cell system according to Embodiment 1 of the present invention, and FIG. 2 shows a fluid flow restricting member disposed in an off-gas circulation path of the fuel cell system shown in FIG. FIG. 3 is a perspective view showing a state in which off-gas flows in the forward direction, and FIG. 3 is a perspective view showing a fluid flow restricting member disposed in the off-gas circulation path of the fuel cell system shown in FIG. It is a figure which shows the state in which off-gas is flowing in the reverse direction. 2 and 3, the off-gas circulation path is shown in cross section.

  As shown in FIGS. 1 to 3, the fuel cell system 1 according to the first embodiment is supplied with an oxidant gas (a gas containing oxygen, usually air) and a fuel gas (a gas containing hydrogen) to generate electric power. A fuel cell 2 is provided. The fuel cell 2 is made of, for example, a solid molecular electrolyte type, and is configured as a stack structure in which a large number of cells are stacked. The fuel cell system 1 includes an oxidizing gas piping system 3 that supplies an oxidizing gas as a reactive gas to the fuel cell 2, and a hydrogen gas piping system 4 that supplies a hydrogen gas as a reactive gas to the fuel cell 2. Yes.

  The oxidizing gas piping system 3 includes an oxidizing gas supply passage 12 that supplies the oxidizing gas humidified by the humidifier 11 to the fuel cell 2, and a discharge passage 13 that guides the oxygen off-gas discharged from the fuel cell 2 to the humidifier 11. And an exhaust passage 14 for introducing oxygen off-gas from the humidifier 11 to the combustor. The oxidizing gas supply path 12 is provided with a compressor 15 that takes in the oxidizing gas in the atmosphere and pumps it to the humidifier 11.

  The hydrogen gas piping system 4 includes a hydrogen tank 21 serving as a hydrogen supply source storing high-pressure hydrogen gas, a hydrogen gas supply path 22 for supplying hydrogen gas (hydrogen supply gas) from the hydrogen tank 21 to the fuel cell 2, a fuel The off-gas circulation path 23 for returning the hydrogen off-gas discharged from the battery 2 to the hydrogen gas supply path 22 and the connecting portion (confluence) between the hydrogen gas supply path 22 and the off-gas circulation path 23 are provided. Of the hydrogen off-gas to the hydrogen gas supply passage 22, an introduction passage 25 for introducing the hydrogen off-gas pressure as a pilot pressure into the ejector 24, and hydrogen that is disposed in the off-gas circulation passage 23 and discharges discharged hydrogen to the outside. And an exhaust valve 26. The ejector 24 joins the hydrogen supply gas from the hydrogen tank 21 with the hydrogen offgas (fuel offgas) from the fuel gas outlet of the fuel cell 2, and the mixed hydrogen gas (mixed fuel gas) after the merging is the fuel cell 2. To be supplied.

  The hydrogen gas supply path 22 is located on the upstream side of the ejector 24, is located on the downstream side of the ejector 24, and the main flow path 22a that is a flow path for guiding the hydrogen supply gas to the ejector 24. And a mixing channel 22b which is a channel leading to the liquid crystal. A shut valve 31 that opens and closes the main flow path 22a and a regulator 32 that adjusts the pressure of the hydrogen supply gas are provided in this order from the upstream side. In the first embodiment, a cylindrical pipe is used as the off-gas circulation path 23.

  A flow that allows the gas (hydrogen offgas, etc.) flowing through the offgas circulation path 23 to flow in the forward and reverse directions downstream of the connection point A with the introduction passage 25 of the offgas circulation path 23 (on the ejector 24 side). A fluid flow restricting member 40 having a path 44 and having a resistance to a forward flow of gas flowing through the off-gas circulation path 23 smaller than a resistance to a reverse flow of gas flowing through the off-gas circulation path 23 is disposed. ing.

  Normally, the hydrogen off-gas flowing through the off-gas circulation path 23 is sucked into the ejector 24 via the fluid flow restriction member 40. Further, the pressure of the hydrogen off gas flowing through the off gas circulation path 23 is introduced as a pilot pressure into the ejector 24 through the introduction path 25.

  As shown in FIGS. 2 and 3 in particular, the fluid flow restriction member 40 includes a ring-shaped base 41 and three opening / closing members 42 a, 42 b, and 42 c each having one end attached to the base 41. The base 41 has the same outer diameter as the inner diameter of the off-gas circulation path 23, and the outer peripheral surface 43 is attached in a state of being in contact with the inner wall 23 a of the off-gas circulation path 23. The fluid flow restriction member 40 has an outer shape (appearance profile) that is larger on the upstream side than on the downstream side.

  The open / close members 42a, 42b, and 42c have a substantially trapezoidal shape when viewed from the side, and each has the same shape. As shown in FIG. 2, these open / close members 42a, 42b and 42c are attached to the base 41 in a normal state and inclined inward, and can be turned around a connecting portion with the base 41 as a fulcrum. It has become. The opening / closing members 42a, 42b, and 42c are formed with gaps therebetween, and the gaps can circulate the gas flowing through the off-gas circulation path 23 in the forward direction and the reverse direction, that is, off-gas circulation. A flow passage 44 is defined that communicates the upstream side and the downstream side of the passage 23. This flow passage 44 (gap) is also present when the open / close members 42a, 42b, and 42c are rotated to be completely closed, and the gas flowing through the off-gas circulation path 23 is forward and backward. Distribution is possible.

  In the first embodiment, the opening / closing members 42a, 42b, and 42c are formed of an elastic member such as resin or rubber, and pressure is applied to the opening / closing members 42a, 42b, and 42c by the gas flowing through the off-gas circulation path 23. In addition, the opening / closing members 42a, 42b, and 42c are elastically deformed, so that the opening / closing members are rotated and opened using the connection portion with the base 41 as a fulcrum.

When the fuel cell and the oxidant gas are supplied to the fuel cell 2 in the fuel cell system 1 having this configuration,
On the anode side, H ₂ → 2H ⁺ + 2e ⁻
On the cathode side, (1/2) O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O
As a whole fuel cell, H ₂ + (1/2) O ₂ → H ₂ O
Reaction occurs. By this electrochemical reaction, on the anode electrode side, hydrogen offgas mixed with unreacted hydrogen is discharged to the offgas circulation path 23 through a hydrogen discharge port (not shown) together with the generated water. Unnecessary hydrogen off-gas is discharged to the outside from the hydrogen exhaust valve 26 at a desired timing, and water such as generated water is discharged to the outside from a drain port (not shown).

  The hydrogen off-gas discharged to the off-gas circulation path 23 flows in the forward direction (the direction indicated by the arrow X in FIGS. 1 and 2) by the power of the ejector 24. At this time, the open / close members 42a, 42b, and 42c of the fluid flow restriction member 40 are in an open state, and the open / close members 42a, 42b, and 42c are further pushed in the open direction by the forward flow of hydrogen off-gas. The opening area of the path 44 is maximized. Accordingly, the resistance when the hydrogen off-gas flows downstream (in the direction of the arrow X) via the flow passage 44 is reduced, and the hydrogen off-gas circulates efficiently. Moreover, since the fluid flow restriction member 40 does not have a driving portion like the valve body of the conventional check valve, it can be prevented from being frozen or worn.

  On the other hand, the hydrogen supply gas supplied from the hydrogen tank 21 is supplied from the hydrogen tank 21 via the shut valve 31 and the regulator 32 by the power of the ejector 24. And is supplied to the fuel cell 2.

  Here, if the power of the ejector 24 increases, the flow rate of the hydrogen supply gas supplied from the main flow passage 22a increases, or the circulation amount of the hydrogen offgas circulating in the offgas circulation passage 23 decreases, and the hydrogen offgas and / or Alternatively, when the supply hydrogen gas flows through the off-gas circulation path 23 in the reverse direction (the direction indicated by the arrow Y in FIG. 3), the flow in the reverse direction causes the opening and closing members 42a, 42b, and 42c of the fluid circulation restriction member 40 to As shown in FIG. 3, the opening / closing members 42 a, 42 b and 42 c are deformed so as to rotate in the closing direction, and the opening area of the flow passage 44 is reduced (narrowed). Therefore, the resistance of the gas flowing upstream (in the arrow Y direction) via the flow passage 44 is increased, and the reverse flow of the gas can be suppressed. Also at this time, similarly to the above, since the fluid flow restriction member 40 does not have a driving portion, it is possible to suppress freezing or wear. Further, at this time, the fluid flow restriction member 40 does not completely seal the gas flowing in the reverse direction, so that the pressure loss with respect to the forward flow can be reduced.

  In the first embodiment, the case where the fluid flow restriction member 40 is configured to open and close by rotating the three open / close members 42a, 42b, and 42c is not limited to this, but the fluid flow restriction member is not limited thereto. 40 has a flow passage 44 through which the gas flowing through the off-gas circulation path 23 can flow in the forward direction and the reverse direction, and the resistance to the forward flow of the gas flowing through the off-gas circulation path 23 is a reverse flow. Other configurations such as the configurations shown in FIGS. 4 to 6 may be provided as long as the configuration is smaller than the resistance to the above.

  Specifically, the fluid flow restriction member 50 shown in FIGS. 4 to 6 includes a ring-shaped base 41 and a mesh-like member 51 formed on the surface of the base 41. The plurality of mesh portions 52 are formed. As shown in FIGS. 5 and 6, each mesh portion 52 has a plurality of openings 53 that are opened in a substantially square shape, and has four sides that are edges that define the substantially square opening 53. Opening and closing members 52a, 52b, 52c and 52d are respectively attached.

  The opening / closing members 52a, 52b, 52c and 52d have a substantially trapezoidal shape, and each has the same shape. As shown in FIG. 5, these opening / closing members 52a, 52b, 52c and 52d are each attached to an edge portion defining the opening 53 in an inclined state in the normal state. The connecting portion can be turned as a fulcrum. The opening / closing members 52a, 52b, 52c, and 52d are formed with gaps therebetween, and the gaps allow the gas flowing through the off-gas circulation path 23 to flow in the forward direction and the reverse direction. It has become. This flow passage 54 (gap) is also formed when the open / close members 52a, 52b, 52c and 52d are turned into a completely closed state, and the gas flowing through the off-gas circulation passage 23 is forward and reverse. Distribution is possible in the direction.

  Similarly to the fluid flow restriction member 40, the fluid flow restriction member 50 is in the open state in the open / close members 52a, 52b, 52c and 52d in a normal state. When the hydrogen off-gas flows in the forward direction by the power of the ejector 24, the forward flow of the hydrogen off-gas pushes the opening / closing members 52a, 52b, 52c and 52d in the opening direction, thereby maximizing the flow passage 54. Therefore, the resistance when the hydrogen offgas flows downstream through the flow passage 54 is reduced, and the hydrogen offgas circulates efficiently.

  Similarly to the above, when the hydrogen off gas and / or the supplied hydrogen gas flow in the off gas circulation path 23 in the reverse direction, the flow in the reverse direction causes the opening / closing members 52a, 52b, 52c and 52d to be upstream. As shown in FIG. 6, the opening / closing members 52a, 52b, 52c and 52d are deformed so as to rotate in the closing direction, and the flow passage 54 becomes narrow. Therefore, the resistance of the gas flowing upstream via the flow passage 54 is increased, and the reverse flow of the gas can be suppressed.

  In the case of the fluid flow restriction member 50, similarly to the fluid flow restriction member 40, since the fluid flow restriction member 50 does not have a drive portion, it can be prevented from being frozen or worn. Furthermore, since the fluid flow restriction member 50 does not completely seal the gas flowing in the reverse direction, the pressure loss with respect to the forward flow can be reduced.

  In the first embodiment, the fluid flow restriction member 40 or 50 having three opening / closing members or four opening / closing members has been described. However, the present invention is not limited to this, and the number of opening / closing members is one or two, or There may be five or more. Further, without providing an opening / closing member, the fluid flow restriction member is deformed in accordance with the direction of the gas flowing through the off-gas circulation path 23, thereby changing the size of the flow path, etc. However, it may be smaller than the resistance to the flow in the reverse direction.

(Embodiment 2)
Next, a fuel cell system according to a second embodiment of the present invention will be described with reference to the drawings. In the second embodiment, the same members as those in the fuel cell system described in the first embodiment are the same. The detailed description is abbreviate | omitted.

  FIG. 7 is a view showing the main part of the fuel cell system according to the second embodiment, and FIG. 8 is a cross-sectional view showing a fluid flow restricting member disposed in the off-gas circulation path of the fuel cell system shown in FIG. FIG. 9 is a cross-sectional view showing a fluid flow restricting member disposed in the off-gas circulation path of the fuel cell system shown in FIG. 7, and the off-gas is reversed. It is a figure which shows the state which is flowing in the direction.

  The difference between the fuel cell system 10 according to the second embodiment and the fuel cell system 1 according to the first embodiment is the configuration of the fluid flow restriction member. That is, as shown in FIGS. 8 and 9, the fluid flow restriction member 60 according to the second embodiment is downstream of the connection point A with the introduction passage 25 of the off-gas circulation path 23, as in the first embodiment. (Ejector 24 side) It is provided with the valve body 61, the valve seat 62, and the coil spring 63 which urges | biases the valve body 61 toward the valve seat 62, and is comprised.

  At a position where the fluid circulation restriction member 60 of the off gas circulation path 23 is disposed, the valve body 61 accommodates the valve body 61 so as to be movable in the upstream and downstream direction of the gas flowing through the off gas circulation path 23. Is formed. This valve body accommodating part 65 has a diameter larger than the diameter of the off-gas circulation path 23, and the upstream side (lower part in FIG. 8 and FIG. 9) has a curved concave shape. A coil spring 63 is fixed to a portion communicating with the off-gas circulation path 23 on the upstream side of the valve body housing portion 65. Further, in the portion communicating with the off-gas circulation path 23 on the downstream side (the upper portion in FIGS. 8 and 9) of the valve body housing portion 65, the difference in diameter between the off-gas circulation path 23 and the valve body housing portion 65 is shown. A demarcating step 66 is formed.

  The valve body 61 includes a substantially hemispherical portion 61a having a substantially hemispherical shape, and leg portions 61b, 61c, and 61d standing upright from the substantially hemispherical portion 61a. In the valve body 61, the substantially hemispherical portion 61a is fixed to the coil spring 63. In a normal state, the tip surfaces of the leg portions 61b and 61d are in contact with the step portion 66 by the urging force of the coil spring 63 ( Therefore, the valve seat 62 is constituted by a part of the step portion 66. A flow passage 64 that connects the upstream side and the downstream side of the off-gas circulation path 23 is formed by a gap formed between the leg portions 61b, 61c, and 61d. That is, the legs 61b, 61c and 61d define a part of the flow path 64.

  Further, in this state, the gap defined by the spiral shape of the coil spring 63 is a gap that is large enough to allow the gas flowing through the off-gas circulation path 23 to flow properly in the forward direction. Therefore, the valve body 61 is in a normally open position when the normal state and gas flow in the forward direction.

  In addition, it is preferable that the valve body 61 is made of a material having high water repellency from the viewpoint of suppressing adhesion of water droplets to the valve body 61 and further preventing freezing. For this reason, in Embodiment 2, the valve body 61 is formed of a material having higher water repellency than the inner wall 23 a that defines the off-gas circulation path 23.

  When the hydrogen off-gas flows in the forward direction by the power of the ejector 24, the fluid flow restricting member 60 is in a state where the tip surfaces of the leg portions 61b and 61d are in contact with the stepped portion 66 as shown in FIG. Off-gas flows toward the downstream side (in the direction of arrow X shown in FIG. 8). At this time, the valve body 61 has a substantially hemispherical portion where the hydrogen off gas strikes, so that the resistance when the hydrogen off gas flows downstream is reduced. Further, since the flow passage 64 is formed in the valve body 61, the hydrogen off-gas flows downstream through the flow passage 64. As a result, the resistance is further reduced, and the hydrogen off-gas circulates efficiently. Further, the contact area between the valve body 61 and the valve seat 62 is the contact area between the tip surfaces of the leg portions 61b and 61d and the valve seat 62, so that the valve seat 62 and the valve body are compared with the conventional check valve. Since the contact area with 61 can be greatly reduced, the fluid flow restricting member 60 is difficult to freeze, and even if it freezes, the valve seat 62 is less likely to malfunction.

  Similarly to the first embodiment, when the hydrogen off gas and / or the supplied hydrogen gas flows through the off gas circulation path 23 in the reverse direction (the arrow Y direction shown in FIG. 9), Against the urging force of the coil spring 63, the valve body 61 is pushed in the upstream direction (the direction of the arrow Y shown in FIG. 9), and the coil spring 63 is pressed and contracted in close contact with the coil spring 63 as shown in FIG. Accordingly, the gap defined by the helical shape of the coil spring 63 is narrowed, the resistance of the gas flowing upstream through the flow passage 64 is increased, and the backflow of gas can be suppressed. As described above, the fluid circulation restriction member 60 has a feature that the resistance to the forward flow of the gas flowing through the off-gas circulation path 23 is smaller than the resistance to the backward flow. Furthermore, since the fluid flow restriction member 60 does not completely seal the gas flowing in the reverse direction, the pressure loss with respect to the forward flow can be reduced.

  In the second embodiment, the valve body 61 including the substantially hemispherical portion 61a and the leg portions 61b, 61c, and 61d standing from the substantially hemispherical portion 61a is described as an example. The valve body has a flow passage through which the gas flowing through the off-gas circulation path 23 can flow in the forward direction and the reverse direction, and the resistance to the forward flow is greater than the resistance to the reverse flow. For example, another configuration as shown in FIG. 10 or FIG. 11 may be provided.

  Specifically, the valve body 71 shown in FIG. 10 includes a substantially spherical body portion 71a and four leg portions 71b, 71c, 71d, and 71e that are erected at a distance from the substantially spherical body portion 71a. It is configured. In the case of this valve body 71, a flow passage that connects the upstream side and the downstream side of the off-gas circulation path 23 is formed by a gap formed between the leg portions 71b, 71c, 71d, and 71e, and an arrow shown in FIG. Gas flows in the X direction or in the opposite direction. Further, the side of the substantially spherical body 71a opposite to the side where the legs 71b, 71c, 71d and 71e are formed is fixed to the coil spring 63 (see FIGS. 8 and 9). And the fluid flow restricting member provided with this valve body 71 also has a resistance to the forward flow of the gas flowing through the off-gas circulation path 23 as compared to the resistance to the reverse flow, like the fluid flow restricting member 60 described above. Is also small.

  In addition, as shown in FIG. 11, a valve body 81 composed of a substantially hemispherical portion 61a and a mesh-shaped cylindrical member 82 provided in a substantially hemispherical portion 61a shape may be used. In this case, the mesh (a plurality of openings) of the cylindrical member 82 serves as a flow path that connects the upstream side and the downstream side of the off-gas circulation path 23. The operation of the valve body 81 is the same as that of the valve body 61, and the fluid flow restricting member provided with the valve body 81 is similar to the fluid flow restricting member 60 described above. It has the feature that the resistance to the forward flow is smaller than the resistance to the reverse flow.

It is a figure which shows the principal part of the fuel cell system concerning Embodiment 1 of this invention. FIG. 2 is a perspective view showing a fluid flow restricting member disposed in an off gas circulation path of the fuel cell system shown in FIG. 1 and showing a state in which off gas flows in a forward direction. FIG. 2 is a perspective view showing a fluid flow restricting member disposed in an off-gas circulation path of the fuel cell system shown in FIG. 1 in a transparent manner, and showing a state where off-gas flows in the reverse direction. It is a perspective view which shows the fluid distribution control member arrange | positioned in the off-gas circuit of the fuel cell system concerning other embodiment of this invention. It is a figure which expands and shows a part of fluid distribution restriction member shown in Drawing 4, and is a figure showing the state where off gas is flowing forward. It is a figure which expands and shows a part of fluid distribution restriction member shown in Drawing 4, and is a figure showing the state where off gas is flowing in the reverse direction. It is a figure which shows the principal part of the fuel cell system concerning Embodiment 2 of this invention. FIG. 8 is a cross-sectional view showing a fluid flow restricting member disposed in an off-gas circulation path of the fuel cell system shown in FIG. 7, and showing a state in which off-gas flows in the forward direction. FIG. 8 is a cross-sectional view showing a fluid flow restriction member disposed in an off-gas circulation path of the fuel cell system shown in FIG. 7 and showing a state in which off-gas flows in the reverse direction. It is a perspective view of the valve body which is a component of the fluid distribution control member concerning other embodiment of this invention. It is a side view of the valve body which is a component of the fluid distribution restriction member concerning other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 10 ... Fuel cell system, 2 ... Fuel cell, 21 ... Hydrogen tank, 22 ... Hydrogen gas supply path, 23 ... Off-gas circulation path, 24 ... Ejector, 40, 50, 60 ... Fluid distribution restriction member, 41 ... Base, 42a-42d ... Opening / closing member, 44, 54, 64 ... Flow passage, 51 ... Mesh member, 52 ... Mesh part, 52a-52e ... Opening / closing member, 53 ... Opening part, 61, 71, 81 ... Valve body, 61a, 71a: substantially hemispherical part, 61b to 61d, 71b to 71e ... leg part, 62 ... valve seat, 63 ... coil spring, 65 ... valve body accommodating part, 82 ... cylindrical member

Claims (10)

A fuel cell, a gas supply path for circulating a supply gas supplied to the fuel cell, an off-gas circulation path for circulating off-gas discharged from the fuel cell and supplying the fuel cell again, and the gas supply path; An ejector that is disposed at a junction with an off-gas circulation path and that mixes the supply gas and the off-gas,
The flow path is provided in the off-gas circulation path and allows the gas flowing through the off-gas circulation path to flow in the forward direction and the reverse direction, and the resistance to the forward flow is greater than the resistance to the reverse flow. A fuel cell system comprising a small fluid flow restriction member.   The fuel cell system according to claim 1, wherein the fluid flow restriction member includes a valve body and a valve seat, and the flow passage is formed in the valve body.   The fuel cell system according to claim 2, wherein the valve body is formed of a material having higher water repellency than an inner wall that defines the off-gas circulation path.   4. The fuel cell system according to claim 2, wherein the valve body is disposed so that the fluid flow restriction member is normally opened. 5.   The fuel cell system according to any one of claims 2 to 4, wherein the valve body is formed with a plurality of abutting portions that define a part of the flow passage and abut against the valve seat.   The fuel cell system according to claim 1, wherein the fluid flow restriction member is deformable according to a direction of gas flowing through the off-gas circulation path.   The fuel cell system according to claim 6, wherein the fluid flow restriction member has an upstream outer shape larger than a downstream outer shape of the forward flow.   The fluid flow restriction member expands an opening area of the flow passage according to the forward flow and reduces an opening area of the flow passage according to the reverse flow. 8. The fuel cell system according to 7.   The flow passage is defined by an opening / closing member, and the opening / closing member rotates in an opening direction in accordance with the forward flow to expand an opening area of the flow passage, thereby causing the flow in the reverse direction. The fuel cell system according to claim 8, wherein the fuel cell system is rotated in a closing direction to reduce an opening area of the flow passage. The fuel according to claim 9, wherein the opening / closing member rotates with one end as a fulcrum and the other end as a free end, and is inclined toward the closing direction with respect to the direction of gas flowing through the off-gas circulation path. Battery system.

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