JP2024034142A - fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent exhaust gas, discharged from a fuel cell stack, from flowing into a supply passage.

SOLUTION: A fuel cell system 10 comprises: a fuel cell unit 11 having a fuel cell stack 21 which generates power by a reaction of oxygen gas and fuel gas, a supply passage 34 which supplies gas containing the oxygen gas to the fuel cell stack 21, and an exhaust passage 37 to which exhaust gas is discharged from the fuel cell stack 21; and a housing 12 which houses the fuel cell unit 11. The supply passage 34 is provided with an inflow port 31 which is opened to the inside of the housing 12 so as to flow the gas from the inside of the housing 12 into the supply passage 34. The exhaust passage 37 is provided with an outflow port 39 which is opened to the inside of the housing 12 so as to flow the exhaust gas out of the exhaust passage 37. The inflow port 31 is located below the outflow port 39 in a gravity direction Z.

SELECTED DRAWING: Figure 4

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a fuel cell system.

The fuel cell system described in Patent Document 1 includes a fuel cell unit having a fuel cell stack, a supply channel, and a discharge channel. A fuel cell stack generates electricity through a reaction between oxygen gas and fuel gas. The supply channel supplies gas containing oxygen gas to the fuel cell stack. Exhaust gas is discharged from the fuel cell stack into the discharge flow path.

Japanese Patent Application Publication No. 2006-73309

In a fuel cell system in which a fuel cell unit is housed in a casing, the inlet of the supply channel and the outlet of the discharge channel may be opened inside the casing due to layout constraints or the like. Gas flows into the supply channel from inside the housing through the inlet. Exhaust gas flows out of the exhaust channel via the outlet. Oxygen gas from the gas supplied to the fuel cell stack from the supply channel is consumed in the fuel cell stack. Therefore, the oxygen concentration of the exhaust gas flowing out from the exhaust channel through the outlet becomes lower than the oxygen concentration of the gas inside the casing. If such exhaust gas flows into the supply flow path, the oxygen concentration of the gas supplied to the fuel cell stack may decrease, which may cause a decrease in the performance of the fuel cell stack. Therefore, it has been desired to suppress the inflow of exhaust gas into the supply channel.

A fuel cell system that solves the above problems includes a fuel cell stack that generates electricity by a reaction between oxygen gas and fuel gas, a supply channel that supplies gas containing the oxygen gas to the fuel cell stack, and a flow path that supplies the gas containing the oxygen gas to the fuel cell stack. A fuel cell system comprising: a fuel cell unit having an exhaust flow path through which exhaust gas is discharged; and a housing housing the fuel cell unit, the supply flow path having an opening inside the housing. , an inlet is formed in which the gas flows into the supply channel from the inside of the casing, and an inlet is formed in the discharge channel, and an inlet is formed in the discharge channel, and a flow port opens into the interior of the casing and causes the exhaust gas to flow out from the discharge channel. An outlet is formed, and the inlet is located below the outlet in the direction of gravity.

According to the above configuration, oxygen gas from the gas supplied to the fuel cell stack from the supply channel is consumed in the fuel cell stack. Therefore, the oxygen concentration of the exhaust gas flowing out from the exhaust channel through the outlet becomes lower than the oxygen concentration of the gas inside the casing. Further, as the exhaust gas receives heat from the fuel cell stack associated with power generation, the temperature of the exhaust gas becomes higher than the temperature of the gas inside the casing. Due to these differences in oxygen concentration and temperature, the gas having a higher oxygen concentration than the exhaust gas is located inside the housing lower in the direction of gravity than the exhaust gas flowing out from the exhaust flow path via the outlet. Since the inlet is located below the outlet in the direction of gravity, gas having a higher oxygen concentration than the exhaust gas can flow from the inlet into the supply channel. Therefore, it is possible to suppress exhaust gas discharged from the fuel cell stack from flowing into the supply channel.

In the fuel cell system, the exhaust flow path is formed with an exhaust port that opens into the fuel cell stack and discharges the exhaust gas from the inside of the fuel cell stack to the exhaust flow path, and the exhaust port and the The discharge flow path between the outlet and the outlet may be located at a position higher than the outlet in the direction of gravity.

According to the above configuration, although the exhaust gas contains water generated by power generation in the fuel cell stack, this water tends to flow through the exhaust flow path from the exhaust port toward the outlet. Therefore, water in the exhaust gas can be suitably discharged from the outlet.

The fuel cell system may include a fan that generates a flow of the gas from the inlet to the outlet inside the casing.
According to the above configuration, the exhaust gas flowing out from the outlet is less likely to flow toward the inlet than when a gas flow from the outlet to the inlet is generated inside the housing. Therefore, it is possible to further suppress exhaust gas discharged from the fuel cell stack from flowing into the supply channel.

In the fuel cell system, the casing includes an upper wall, a lower wall located below the upper wall in the direction of gravity, and a cylindrical side wall connecting the upper wall and the lower wall, The supply channel includes an air cleaner that is located at the inlet and is capable of removing foreign matter from the gas flowing from the inlet into the supply channel, and the inlet is lower than the lower wall in the direction of gravity. It may be located close to the upper wall.

According to the above configuration, the inflow port is located higher inside the casing than when the inflow port is located closer to the bottom wall than the top wall in the direction of gravity. Therefore, when performing maintenance on the air cleaner, the operator can look into the inside of the casing from above in a comfortable position while standing, and can perform the work. Furthermore, if the inlet is located closer to the bottom wall than the top wall in the direction of gravity, maintenance of the air cleaner may be performed, for example, through a maintenance opening provided in the side wall of the housing. Compared to such a case, according to the above configuration, the worker does not have to work in an awkward bent-over posture. Therefore, work efficiency in air cleaner maintenance can be improved.

According to this invention, it is possible to suppress exhaust gas discharged from the fuel cell stack from flowing into the supply channel.

It is a side view showing a forklift. It is a perspective view showing a housing. FIG. 2 is a schematic diagram showing a fuel cell unit. FIG. 1 is a sectional view showing a fuel cell system according to a first embodiment. FIG. 3 is a sectional view showing a fuel cell system according to a second embodiment.

[First embodiment]
A first embodiment of a fuel cell system will be described below with reference to the drawings.
<Fuel cell system>
As shown in FIG. 1, the fuel cell system 10 includes a fuel cell unit 11 and a housing 12 that houses the fuel cell unit 11. The fuel cell system 10 is mounted on a forklift F. Note that the fuel cell system 10 may be applied to industrial vehicles other than the forklift F, and may also be applied to vehicles other than industrial vehicles, such as passenger cars, buses, trucks, etc.

<Housing>
As shown in FIGS. 1 and 2, the housing 12 includes an upper wall 12b, a lower wall 12a, and a side wall 12c. The side wall 12c has a cylindrical shape that connects the upper wall 12b and the lower wall 12a. Note that assuming that the housing 12 is placed on a horizontal plane, the direction of gravity is indicated by the Z axis, and the directions along the horizontal plane are indicated by the X and Y axes. The X-axis, Y-axis, and Z-axis are orthogonal to each other. The gravitational direction is also referred to as the gravitational direction Z below. The direction in which the X-axis extends is also referred to as a first direction X, and the direction in which the Y-axis extends is also referred to as a second direction Y.

As shown in FIG. 2, the lower wall 12a is located below the upper wall 12b in the direction of gravity Z. The lower wall 12a and the upper wall 12b face each other in the gravity direction Z. The side wall 12c includes a first side wall 12d and a second side wall 12e that face each other in the first direction X. A plurality of vent holes 12f are formed in the first side wall 12d. The vent hole 12f is a through hole that penetrates the first side wall 12d.

At least a portion of the top wall 12b may be removable from the housing 12. In this embodiment, the entire upper wall 12b is removable from the housing 12. By removing the upper wall 12b from the housing 12, the upper part of the housing 12 is opened. Maintenance of the members inside the housing 12 is possible through this upper opening.

A portion of side wall 12c may be removable from other portions of side wall 12c. A removable portion of the side wall 12c is referred to as a small wall portion 12g. The small wall portion 12g of this embodiment is located below the gravity direction Z of the first side wall 12d. The small wall portion 12g constitutes a part of the first side wall 12d. By removing the small wall portion 12g from the side wall 12c, a portion of the first side wall 12d is opened. Maintenance of the members inside the housing 12 is possible through this opening.

<Forklift>
As shown in FIG. 1, the forklift F has a seat Fa. The forklift F has a storage portion Fb below the seat Fa. A fuel cell system 10 is housed in the housing portion Fb. The forklift F operates using electric power generated by the fuel cell unit 11 of the fuel cell system 10.

With the fuel cell system 10 mounted on the forklift F, the housing 12 is positioned such that the left-right direction of the forklift F matches the first direction X, and the front-rear direction of the forklift F matches the second direction Y. are doing. The upper wall 12b of the housing 12 is located below the seat Fa of the forklift F.

As shown in FIG. 3, the forklift F includes a load 91, a power converter 92, and a key switch 93. The load 91 is a device driven by electric power. The load 91 is, for example, an electric motor driven by electric power. The forklift F travels by driving this electric motor.

The power converter 92 converts the power input to the power converter 92 from the fuel cell unit 11 and outputs the converted power. Power converter 92 includes a DC/DC converter and an inverter. The power output from the power converter 92 is supplied to the load 91. This drives the load 91.

The key switch 93 is operated by the user of the forklift F. The key switch 93 is turned on and off by operation by the user. In the following description, turning off the key switch 93 may be referred to as "key off", and turning on the key switch 93 may be referred to as "key on".

<Fuel cell unit>
The fuel cell unit 11 includes a cathode system 30, an anode system 60, a cooling system 70, a diluter 69, and a control section 80. The fuel cell unit 11 has a fuel cell stack 21 . The fuel cell stack 21 is, for example, a polymer electrolyte fuel cell. The fuel cell stack 21 includes a plurality of fuel cells 22. The fuel cell 22 includes an anode to which an anode gas is supplied, a cathode to which a cathode gas is supplied, and an electrolyte membrane disposed between the anode and the cathode. The fuel cell 22 is sandwiched between separators.

The cathode system 30 includes a cathode channel 23 through which cathode gas flows. The cathode flow path 23 is provided, for example, in a separator facing the cathode electrode in the fuel cell stack 21.

The anode system 60 includes an anode channel 26 through which an anode gas flows. The anode flow path 26 is provided, for example, in a separator facing the anode electrode in the fuel cell stack 21. The anode flow path 26 includes an anode inlet 27 and an anode outlet 28 . The anode gas flows into the anode channel 26 from the anode inlet 27 and flows out of the anode channel 26 from the anode outlet 28 .

The fuel cell stack 21 generates power by reacting the anode gas flowing through the anode flow path 26 and the cathode gas flowing through the cathode flow path 23 . The cathode gas is oxygen gas. Anode gas is fuel gas. Therefore, the fuel cell stack 21 generates electricity through the reaction between oxygen gas and fuel gas. Examples of the fuel gas include hydrogen gas.

The anode system 60 includes a tank 61 , an anode gas supply section 62 , a supply path 63 , a circulation path 64 , a gas-liquid separator 65 , a circulation pump 66 , and an exhaust drain valve 67 .
Tank 61 stores anode gas. The anode gas supply unit 62 is supplied with anode gas from the tank 61 . The anode gas supply unit 62 is a member for adjusting the amount of anode gas supplied to the fuel cell stack 21. The amount of anode gas supplied to the fuel cell stack 21 can be adjusted by controlling the anode gas supply section 62. As the anode gas supply section 62, for example, a solenoid valve such as an injector can be used.

The supply path 63 connects the anode gas supply section 62 and the anode inlet 27. The anode gas injected from the anode gas supply section 62 is supplied to the fuel cell stack 21 through the supply path 63.

The circulation path 64 connects the anode outlet 28 and the supply path 63. Anode exhaust gas flows through the circulation path 64 . The anode exhaust gas includes unreacted anode gas and produced water. The generated water is water generated by power generation in the fuel cell stack 21. The circulation path 64 is a path for returning unreacted anode gas contained in the anode exhaust gas to the supply path 63.

A gas-liquid separator 65 is provided in the circulation path 64. The gas-liquid separator 65 separates the anode exhaust gas into anode gas and produced water. The generated water separated from the anode exhaust gas is stored in the gas-liquid separator 65.

A circulation pump 66 is provided in the circulation path 64. The circulation pump 66 supplies the anode gas separated from the anode exhaust gas by the gas-liquid separator 65 to the supply path 63. This circulates the anode gas.

The exhaust drain valve 67 is connected to the gas-liquid separator 65. The exhaust drain valve 67 is switched between an open state and a closed state. When the exhaust drain valve 67 is in the open state, generated water is discharged from the gas-liquid separator 65. The exhaust drainage valve 67 may be switched from the closed state to the open state when the amount of produced water stored in the gas-liquid separator 65 exceeds a threshold value. The exhaust drain valve 67 may be switched from a closed state to an open state at predetermined time intervals.

Gas-liquid separator 65 is connected to diluter 69. When the exhaust drain valve 67 is opened, the produced water and the anode exhaust gas stored in the gas-liquid separator 65 are supplied to the diluter 69.
The cathode system 30 includes a supply channel 34 and a discharge channel 37. In other words, the fuel cell unit 11 has the supply channel 34 and the discharge channel 37. The cathode system 30 includes an electric compressor 32, an intercooler 33, a sealing valve 40, and a pressure regulating valve 41.

As shown in FIGS. 3 and 4, an inlet 31 is formed in the supply channel 34. The inlet 31 is located, for example, at the upstream end of the supply channel 34. The inlet 31 opens into the interior of the housing 12 . The inlet 31 allows the oxygen-containing gas G1 to flow into the supply channel 34 from inside the casing 12.

The supply channel 34 includes an air cleaner 31a. The air cleaner 31a is located at the inlet 31. The air cleaner 31a can remove foreign matter from the gas G1 flowing into the supply channel 34 from the inlet 31. The gas G1 that has flowed into the inlet 31 is supplied to the electric compressor 32 through the air cleaner 31a.

The electric compressor 32 is driven by an electric motor. The electric compressor 32 supplies gas G1 to the fuel cell stack 21. Specifically, the electric compressor 32 compresses the gas G1 that has flowed into the supply channel 34 from the inlet 31 and supplies the compressed gas G1 to the fuel cell stack 21 . Thereby, the supply channel 34 supplies the gas G1 containing oxygen gas to the fuel cell stack 21. Gas G1 supplied from the electric compressor 32 to the fuel cell stack 21 flows through the cathode channel 23.

The intercooler 33 is supplied with gas G1 discharged from the electric compressor 32. The intercooler 33 cools the gas G1 supplied from the electric compressor 32. The gas G1 cooled by the intercooler 33 is supplied to the fuel cell stack 21.

A cathode inlet 24 is formed in the supply channel 34 . The cathode inlet 24 is located, for example, at the downstream end of the supply channel 34. The cathode inlet 24 opens into the inside of the fuel cell stack 21 . The supply channel 34 and the cathode channel 23 are connected via the cathode inlet 24 . Gas G1 flows out from the supply channel 34 to the cathode channel 23 via the cathode inlet 24.

The supply channel 34 includes a first supply channel 35 and a second supply channel 36. The first supply channel 35 connects the inlet 31, the electric compressor 32, and the intercooler 33. The second supply flow path 36 connects the intercooler 33 and the cathode flow path 23 .

A cathode discharge port 25 serving as a discharge port is formed in the discharge flow path 37 . The cathode discharge port 25 is located, for example, at the upstream end of the discharge channel 37. The cathode outlet 25 opens into the inside of the fuel cell stack 21 . The discharge passage 37 and the cathode passage 23 are connected via the cathode discharge port 25 . Exhaust gas G2 flows from the cathode channel 23 into the exhaust channel 37 via the cathode outlet 25. That is, the cathode discharge port 25 discharges the exhaust gas G2 from the inside of the fuel cell stack 21 to the discharge flow path 37. Exhaust gas G2 is discharged from the fuel cell stack 21 into the discharge flow path 37. The exhaust flow path 37 is a passage through which the exhaust gas G2 flows. The exhaust gas G2 is a cathode gas discharged from the fuel cell stack 21, and is a cathode gas containing produced water. A part of the oxygen gas contained in the gas G1 supplied to the fuel cell stack 21 from the supply channel 34 is consumed for power generation by the fuel cell stack 21. As a result, the oxygen concentration of the exhaust gas G2 discharged from the fuel cell stack 21 to the exhaust flow path 37 is lower than the oxygen concentration of the gas G1.

A diluter 69 is provided in the discharge channel 37 . Thereby, the discharge flow path 37 connects the cathode flow path 23 and the diluter 69. The exhaust gas G2 is discharged from the discharge flow path 37 to the diluter 69. The diluter 69 dilutes the anode exhaust gas supplied from the gas-liquid separator 65 with the exhaust gas G2 and discharges the diluted anode exhaust gas.

An outlet 39 is formed in the discharge channel 37 . Outlet 39 is located downstream of diluter 69 in discharge channel 37 . The outlet 39 is located, for example, at the downstream end of the discharge channel 37. The outlet 39 opens into the inside of the housing 12 . The outflow port 39 allows the exhaust gas G2 to flow out from the exhaust flow path 37. The anode exhaust gas diluted by the exhaust gas G2 in the diluter 69 is also discharged from the outlet 39.

The sealing valve 40 is provided in the supply channel 34. The sealing valve 40 of this embodiment is provided in the second supply channel 36. The sealing valve 40 may be provided in the first supply channel 35. The sealing valve 40 is, for example, a butterfly valve that seals the supply channel 34. The sealing valve 40 is switched between an open state and a closed state. When the sealing valve 40 is in the open state, the gas G1 is supplied to the cathode channel 23 via the supply channel 34.

The pressure regulating valve 41 is provided in the discharge flow path 37. The pressure regulating valve 41 is, for example, a butterfly valve. By adjusting the opening degree of the pressure regulating valve 41, the internal pressure of the fuel cell stack 21 is adjusted. The smaller the opening degree of the pressure regulating valve 41, the higher the internal pressure of the fuel cell stack 21. When the sealing valve 40 and the pressure regulating valve 41 are fully closed, the cathode flow path 23 is sealed.

As shown in FIG. 3, the cooling system 70 includes a refrigerant circulation path 71, a heat exchanger 72, and a refrigerant pump 74. The cooling system 70 includes a fan 73. That is, the fuel cell system 10 includes a fan 73.

Refrigerant circulation path 71 connects fuel cell stack 21 and heat exchanger 72 . The refrigerant pump 74 circulates refrigerant through the refrigerant circulation path 71 . For example, water, antifreeze, or air is used as the refrigerant. Refrigerant pump 74 is driven by an electric motor.

Heat exchanger 72 is, for example, a radiator. The heat exchanger 72 may exchange heat between the outside air and the refrigerant. Fan 73 is rotated by an electric motor. Fan 73 blows air toward heat exchanger 72 . The cooling efficiency of the refrigerant inside the heat exchanger 72 is increased by blowing air from the fan 73. The fuel cell stack 21 is cooled by supplying the refrigerant cooled by the heat exchanger 72 to the fuel cell stack 21 through the refrigerant circulation path 71.

As shown in FIG. 4, the heat exchanger 72 is arranged on the second side wall 12e of the housing 12. Heat exchanger 72 is placed on the side of fuel cell stack 21 . As the fan 73 rotates, outside air is drawn into the interior of the housing 12 from the outside of the housing 12 through the vent 12f. Inside the casing 12, that is, around the fuel cell unit 11, a flow W of gas G1 toward the fan 73 is generated from the vent 12f. The flow W in this embodiment is directed in the first direction X inside the casing 12 .

As shown in FIG. 3, the control unit 80 includes a processor 81 and a storage unit 82. The storage unit 82 includes a RAM (Random Access Memory) and a ROM (Read Only Memory). The storage unit 82 stores program codes or instructions configured to cause the processor 81 to execute processes. Storage 82, or computer readable media, includes any available media that can be accessed by a general purpose or special purpose computer. The control unit 80 may be configured by a hardware circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The control unit 80, which is a processing circuit, may include one or more processors that operate according to a computer program, one or more hardware circuits such as ASIC or FPGA, or a combination thereof.

The control unit 80 controls the fuel cell system 10. For example, the control unit 80 controls the output power [kW] of the fuel cell stack 21. The output power of the fuel cell stack 21 changes depending on the amount of cathode gas supplied to the fuel cell stack 21 and the amount of anode gas supplied to the fuel cell stack 21. The output power of the fuel cell stack 21 is the power generated by the fuel cell stack 21. The control unit 80 controls the amount of anode gas supplied to the fuel cell stack 21 by controlling the anode gas supply unit 62 . The control unit 80 controls the amount of cathode gas supplied to the fuel cell stack 21 by controlling the electric compressor 32 .

The control unit 80 controls, for example, the opening degrees of the sealing valve 40 and the pressure regulating valve 41, and also controls the rotation of the fan 73. The control unit 80 can determine whether the key switch 93 is on or off. When the forklift F is keyed off, the control unit 80 stops the power generation of the fuel cell stack 21 by stopping the supply of anode gas and the supply of cathode gas. The control unit 80 stops the supply of anode gas by sealing the anode flow path 26. The anode flow path 26 is sealed by keeping the exhaust and drain valve 67 closed. The control unit 80 stops the supply of cathode gas by sealing the cathode flow path 23 . The cathode channel 23 is sealed by keeping the sealing valve 40 and the pressure regulating valve 41 closed.

When the forklift F is turned on, the control unit 80 causes the fuel cell stack 21 to generate power by supplying anode gas and cathode gas. When the cathode gas is supplied, the control unit 80 maintains the sealing valve 40 in an open state and adjusts the opening degree of the pressure regulating valve 41.

<Position of inlet and outlet inside the housing>
As shown in FIG. 4, the inlet 31 is located below the outlet 39 in the direction of gravity Z. A portion of the supply channel 34 between the inlet 31 and the electric compressor 32 extends in the opposite direction to the first direction X from the electric compressor 32 toward the inlet 31, for example. The inflow port 31 opens in a direction opposite to the first direction X.

The inlet 31 faces the first side wall 12d of the housing 12 in the first direction X. More specifically, the inlet 31 faces the small wall portion 12g of the first side wall 12d. Therefore, maintenance of the air cleaner 31a located at the inlet 31 is possible through the opening of the first side wall 12d created by removing the small wall portion 12g from the side wall 12c.

The ventilation port 12f and the inflow port 31 of the housing 12 do not face each other in the first direction X. The position where the ventilation port 12f is formed in the first side wall 12d and the position of the inflow port 31 are shifted from each other in the direction of gravity Z.

The discharge channel 37 extends in the first direction X from the cathode discharge port 25 toward the outlet 39 . In this embodiment, the discharge channel 37 between the cathode outlet 25 and the outlet 39 extends at the same height in the gravity direction Z. Therefore, the discharge channel 37 between the cathode outlet 25 and the outlet 39 is located at the same height as the outlet 39 in the gravity direction Z.

The outlet 39 faces the fan 73 in the first direction X. The outflow port 39 is open toward the first direction X. Therefore, the inlet 31 and the outlet 39 open in opposite directions.

The inflow port 31 is located at a position closer to the first side wall 12d than the second side wall 12e in the first direction X. The outflow port 39 is located at a position closer to the second side wall 12e than the first side wall 12d in the first direction X. Inside the casing 12 , the outlet 39 is located on the first direction X side relative to the fuel cell stack 21 , and the inflow port 31 is located on the opposite side of the first direction X relative to the fuel cell stack 21 . The outflow port 39 is located away from the inflow port 31 in the first direction X.

A flow W of gas G1 generated inside the housing 12 by the rotation of the fan 73 is directed in the first direction X. Therefore, the direction of the flow W of the gas G1 coincides with the direction from the inlet 31 to the outlet 39. In other words, the fan 73 generates a flow of gas G1 from the inlet 31 toward the outlet 39 inside the casing 12 .

[Operation of the first embodiment]
Next, the operation in the first embodiment will be explained.
Oxygen gas from the gas G1 supplied to the fuel cell stack 21 from the supply channel 34 is consumed in the fuel cell stack 21. Therefore, the oxygen concentration of the exhaust gas G2 flowing out from the exhaust passage 37 via the outlet 39 is lower than the oxygen concentration of the gas G1 inside the housing 12. Further, as the exhaust gas G2 receives heat from the fuel cell stack 21 due to power generation, the temperature of the exhaust gas G2 becomes higher than the temperature of the gas G1 inside the casing 12. Due to these differences in oxygen concentration and temperature, the gas G1 having a higher oxygen concentration than the exhaust gas G2 is located lower in the gravity direction Z inside the casing 12 than the exhaust gas G2 flowing out from the exhaust flow path 37 via the outlet 39. will be located. Since the inlet 31 is located below the outlet 39 in the direction of gravity Z, the gas G1 having a higher oxygen concentration than the exhaust gas G2 easily flows into the supply channel 34 from the inlet 31.

[Effects of the first embodiment]
According to the first embodiment, the following effects can be obtained.
(1-1) The inlet 31 is located below the outlet 39 in the direction of gravity Z. Therefore, the gas G1 having a higher oxygen concentration than the exhaust gas G2 can be caused to flow into the supply channel 34 from the inlet 31. Therefore, it is possible to suppress the exhaust gas G2 discharged from the fuel cell stack 21 from flowing into the supply channel 34.

In the fuel cell system 10, the inlet 31 and the outlet 39 may be provided inside the casing 12 due to restrictions. For example, if it is difficult to arrange the supply channel 34 or the exhaust channel 37 or open the inlet 31 or the outlet 39 in the target on which the fuel cell system 10 is installed, or if it is difficult to remove the exhaust gas G2 from the target. Direct discharge may cause the hydrogen concentration to exceed the specified value. Due to such restrictions, even if the inlet 31 and the outlet 39 are provided inside the housing 12, it is possible to suppress the exhaust gas G2 from flowing into the supply channel 34.

(1-2) A cathode outlet 25 is formed in the exhaust flow path 37, which opens into the inside of the fuel cell stack 21 and allows exhaust gas G2 to flow into the exhaust flow path 37 from the inside of the fuel cell stack 21. The discharge channel 37 between the cathode discharge port 25 and the outlet 39 is located at a position higher than the outlet 39 in the gravity direction Z. Although the exhaust gas G2 contains water generated by power generation in the fuel cell stack 21, this water tends to flow through the exhaust flow path 37 from the cathode outlet 25 toward the outlet 39. Therefore, water in the exhaust gas G2 can be suitably discharged from the outlet 39.

(1-3) A fan 73 is provided that generates a flow W of gas G1 from the inlet 31 toward the outlet 39 inside the casing 12. Therefore, the exhaust gas G2 flowing out from the outlet 39 is less likely to flow toward the inlet 31 than when the gas G1 flows from the outlet 39 toward the inlet 31 inside the housing 12. Therefore, it is possible to further suppress the exhaust gas G2 discharged from the fuel cell stack 21 from flowing into the supply channel 34.

[Second embodiment]
A second embodiment of the fuel cell system will be described below with reference to the drawings. In this embodiment, the positions of the inlet 31 and the outlet 39 inside the housing 12 are different from those in the first embodiment. The following description focuses on the differences from the first embodiment. Descriptions of the same configurations as in the first embodiment will be omitted as appropriate.

As shown in FIG. 5, the inlet 31 in this embodiment is located higher inside the housing 12 than the inlet 31 in the first embodiment. The inlet 31 is located closer to the upper wall 12b than the lower wall 12a in the gravity direction Z. Maintenance of the air cleaner 31a located at the inlet 31 is possible through the opening at the top of the casing 12 when the top wall 12b is removed from the casing 12. Similarly, the outlet 39 is located closer to the upper wall 12b than the lower wall 12a in the direction of gravity Z. Accordingly, also in this embodiment, the inlet 31 is located below the outlet 39 in the direction of gravity Z. Furthermore, the small wall portion 12g is omitted from the first side wall 12d of this embodiment.

Similarly to the first embodiment, in this embodiment as well, the rotation of the fan 73 generates a flow of gas G1 from the inlet 31 toward the outlet 39 inside the housing 12 . The discharge channel 37 between the cathode outlet 25 and the outlet 39 is located at the same height as the outlet 39 in the gravity direction Z.

According to the second embodiment, the same effect as the first embodiment can be achieved.
[Effects of second embodiment]
According to the second embodiment, in addition to the same effects as those of the first embodiment, the following effects can be obtained.

(2-1) The supply channel 34 includes an air cleaner 31a located at the inlet 31 and capable of removing foreign matter from the gas G1 flowing into the supply channel 34 from the inlet 31. The inlet 31 is located closer to the upper wall 12b than the lower wall 12a in the gravity direction Z. Therefore, the position of the inflow port 31 is located higher inside the housing 12 than when the inflow port 31 is located closer to the lower wall 12a than the upper wall 12b in the direction of gravity Z. Therefore, when performing maintenance on the air cleaner 31a, the operator can look into the interior of the housing 12 from above in a comfortable posture while standing, and can perform the work. Furthermore, if the inlet 31 is located closer to the lower wall 12a than the upper wall 12b in the direction of gravity Z, maintenance of the air cleaner 31a can be performed through a maintenance opening provided in the side wall 12c of the housing 12, for example. It is possible to do this. Compared to such a case, according to the present embodiment, the worker does not have to work in an awkward bent-over posture. Therefore, work efficiency in maintenance of the air cleaner 31a can be improved.

[Example of change]
The embodiment can be modified and implemented as follows. The embodiments and the following modified examples can be implemented in combination with each other within a technically consistent range.

In the second embodiment, the inlet 31 may be located closer to the lower wall 12a than the upper wall 12b in the gravity direction Z. The outflow port 39 may be located closer to the lower wall 12a than the upper wall 12b in the gravity direction Z.

The air cleaner 31a may be provided in a portion of the supply channel 34 other than the inlet 31. The air cleaner 31a may be omitted from the supply channel 34.
The housing 12 is not limited to a shape including an upper wall 12b, a lower wall 12a, and a side wall 12c. In short, the shape of the housing 12 can be changed as long as the housing 12 can accommodate the fuel cell unit 11.

○ The housing 12 may house a part of the fuel cell unit 11. For example, part of the supply flow path 34 may be housed in the housing 12, and the other portion of the supply flow path 34 may be located outside the housing 12. In this case as well, the inlet 31 opens inside the housing 12 . For example, a portion of the discharge flow path 37 may be housed in the housing 12, and the other portion of the discharge flow path 37 may be located outside the housing 12. In this case as well, the outlet 39 opens into the interior of the housing 12 .

The flow W of the gas G1 generated inside the housing 12 by the fan 73 may flow in a direction other than the direction from the inlet 31 to the outlet 39. In this case, by adjusting the positional relationship between the fan 73 and the vent 12f, the direction of the flow W of the gas G1 generated inside the housing 12 can be adjusted.

○ The direction in which the inlet 31 opens is not limited to the opposite direction to the first direction X.
In the first embodiment, the inlet 31 does not need to face the small wall portion 12g. Also in this case, if the inlet 31 is provided near the small wall 12g, the air cleaner 31a located at the inlet 31 can be connected to the air cleaner 31a through the opening of the first side wall 12d when the small wall 12g is removed from the side wall 12c. maintenance is possible.

○ The outflow port 39 may open in a direction different from the first direction X. The outlet 39 does not need to face the fan 73.
The direction in which the inflow port 31 opens and the direction in which the outflow port 39 opens may not be opposite to each other.

The outflow port 39 may be located away from the inflow port 31 in the second direction Y. The outflow port 39 may be located at the same position as the inflow port 31 in at least one of the first direction X and the second direction Y. In short, the outflow port 39 only needs to be separated from the inflow port 31 at least in the gravity direction Z.

○ The fan 73 may be omitted from the fuel cell system 10. In this case, the formation of the vent hole 12f in the housing 12 may also be omitted.
- At least a part of the discharge channel 37 between the cathode discharge port 25 and the outlet 39 may be located above the outlet 39 in the direction of gravity Z. In short, the discharge channel 37 between the cathode outlet 25 and the outlet 39 only needs to be located at a position higher than the outlet 39 in the direction of gravity Z.

o At least a portion of the discharge channel 37 between the cathode discharge port 25 and the outlet 39 may be located below the outlet 39 in the direction of gravity Z.
○ The fuel cell system 10 may be used as a stationary power generation device.

Embodiments include configurations described in the appendix below.
<Additional note 1>
The fuel cell stack includes a fuel cell stack that generates power by a reaction between oxygen gas and fuel gas, a supply channel that supplies gas containing the oxygen gas to the fuel cell stack, and an exhaust channel that discharges exhaust gas from the fuel cell stack. a fuel cell unit,
A fuel cell system comprising: a casing that accommodates the fuel cell unit;
The supply channel is formed with an inlet that opens into the interior of the casing and allows the gas to flow from the inside of the casing into the supply channel,
The exhaust flow path is formed with an outlet that opens into the interior of the casing and allows the exhaust gas to flow out of the exhaust flow path,
The fuel cell system is characterized in that the inlet is located below the outlet in the direction of gravity.

<Additional note 2>
The exhaust flow path is formed with an exhaust port that opens into the inside of the fuel cell stack and discharges the exhaust gas from the inside of the fuel cell stack to the exhaust flow path,
The fuel cell system according to <Additional Note 1>, wherein the discharge flow path between the discharge port and the outlet is located at a position higher than the outlet in the direction of gravity.

<Additional note 3>
The fuel cell system according to <Appendix 1> or <Appendix 2>, including a fan that generates a flow of the gas from the inlet to the outlet inside the casing.

<Additional note 4>
The casing includes an upper wall, a lower wall located below the upper wall in the direction of gravity, and a cylindrical side wall connecting the upper wall and the lower wall,
The supply channel includes an air cleaner located at the inlet and capable of removing foreign matter from the gas flowing into the supply channel from the inlet,
The fuel cell system according to any one of <Appendix 1> to <Appendix 3>, wherein the inlet is located closer to the upper wall than the lower wall in the direction of gravity.

G1... Gas, G2... Exhaust gas, W... Flow, Z... Gravity direction, 10... Fuel cell system, 11... Fuel cell unit, 12... Housing, 12a... Lower wall, 12b... Upper wall, 12c... Side wall, 21... Fuel cell stack, 25... cathode outlet (as an outlet), 31... inlet, 31a... air cleaner, 34... supply channel, 37... discharge channel, 39... outlet, 73... fan.

Claims (4)

The fuel cell stack includes a fuel cell stack that generates power by a reaction between oxygen gas and fuel gas, a supply channel that supplies gas containing the oxygen gas to the fuel cell stack, and an exhaust channel that discharges exhaust gas from the fuel cell stack. a fuel cell unit,
A fuel cell system comprising: a casing that accommodates the fuel cell unit;
The supply channel is formed with an inlet that opens into the interior of the casing and allows the gas to flow from the inside of the casing into the supply channel,
The exhaust flow path is formed with an outlet that opens into the interior of the casing and allows the exhaust gas to flow out of the exhaust flow path,
The fuel cell system is characterized in that the inlet is located below the outlet in the direction of gravity. The exhaust flow path is formed with an exhaust port that opens into the inside of the fuel cell stack and discharges the exhaust gas from the inside of the fuel cell stack to the exhaust flow path,
The fuel cell system according to claim 1, wherein the discharge flow path between the discharge port and the outlet is located at a position higher than the outlet in the direction of gravity. 3. The fuel cell system according to claim 1, further comprising a fan that generates a flow of the gas from the inlet to the outlet inside the casing. The casing includes an upper wall, a lower wall located below the upper wall in the direction of gravity, and a cylindrical side wall connecting the upper wall and the lower wall,
The supply channel includes an air cleaner located at the inlet and capable of removing foreign matter from the gas flowing into the supply channel from the inlet,
3. The fuel cell system according to claim 1, wherein the inlet is located closer to the upper wall than to the lower wall in the direction of gravity.

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