JP2023132392A - Vehicle fuel cell system and drainage method for vehicle fuel cell system - Google Patents

Abstract

To suppress fuel cell stack deterioration and stabilize fuel cell stack power generation.SOLUTION: A control unit (96) of a vehicle fuel cell system (10) makes a first determination to determine whether a vehicle is stopped, estimates the amount of water collected at the bottom of the fuel cell stack on the basis of the amount of power generated by the fuel cell stack (12), makes a second determination to determine whether the water volume is greater or less than a water volume threshold, and controls the opening and closing of a valve (58) on the basis of the results of the first determination and the second determination.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vehicular fuel cell system and a method for draining water accumulated in the lower part of a fuel cell stack to the outside of the fuel cell stack.

In recent years, research and development has been conducted on fuel cells that contribute to energy efficiency in order to ensure that more people have access to affordable, reliable, sustainable, and advanced energy.

A fuel cell system includes a fuel cell stack. A fuel cell stack generates electricity through a reaction between anode gas (fuel gas containing hydrogen) and cathode gas (oxidant gas containing oxygen). Water is produced during power generation. Water is discharged to the outside of the fuel cell stack along with off-gas.

The anode off-gas is mainly discharged to the gas-liquid separator. The gas-liquid separator separates the anode off-gas into gas (such as hydrogen) and water. The gas separated by the gas-liquid separator is reused as anode gas. The water separated by the gas-liquid separator is temporarily stored in the gas-liquid separator and then drained to the outside of the gas-liquid separator.

In modern fuel cell systems, high humidity is maintained inside the fuel cell stack. Water accumulates inside such a fuel cell stack. Patent Document 1 discloses a technique for draining water accumulated inside a fuel cell stack to a gas-liquid separator. The fuel cell system of Patent Document 1 has a structure that allows water in the fuel cell stack to be drained to the gas-liquid separator even when the fuel cell stack is tilted.

Japanese Patent Application Publication No. 2021-18850

When the inside of the fuel cell stack is maintained at high humidity, the amount of water stored in the gas-liquid separator also increases. Then, due to the tilt of the vehicle or the like, the proportion of water stored in the gas-liquid separator flowing back into the fuel cell stack increases. When the water accumulated in the fuel cell stack and the water flowing back from the gas-liquid separator are combined, the water inside the fuel cell stack becomes excessive. In particular, when the fuel cell stack is tilted, the amount of water flooding into the power generation cells located below increases. If power generation cells are submerged in water for a long time, not only will power generation become unstable, but the fuel cell stack will deteriorate.

The present invention aims to solve the above-mentioned problems.

A first aspect of the present invention is a fuel cell system for a vehicle that includes a fuel cell stack that generates electricity using an anode gas and a cathode gas, wherein water accumulated at the bottom of the fuel cell stack is removed from the outside of the fuel cell stack. a drainage channel connected to the fuel cell stack for draining water to the fuel cell stack; a throttle that makes the upstream side of the drainage channel higher pressure than the downstream side of the drainage channel; a valve that opens and closes the drainage channel; a control unit that controls opening and closing of the valve, the control unit makes a first determination to determine whether the vehicle is stopped, and determines whether the fuel cell stack is operated based on the amount of power generated by the fuel cell stack. Estimate the amount of water accumulated in the lower part, make a second determination to determine whether the amount of water is greater or less than a water amount threshold, and open or close the valve based on the result of the first determination and the result of the second determination. Control.

A second aspect of the present invention is a drainage method for a fuel cell system for a vehicle equipped with a fuel cell stack that generates electricity using an anode gas and a cathode gas, wherein a drainage flow path connected to the fuel cell stack for draining water to the outside of the fuel cell stack; a throttle that makes the upstream of the drainage flow path higher pressure than the downstream of the drainage flow path; a valve that opens and closes a road; and a computer that controls opening and closing of the valve; the computer makes a first determination to determine whether the vehicle is stopped; to estimate the amount of water accumulated at the bottom of the fuel cell stack, perform a second determination to determine whether the amount of water is greater or less than a water amount threshold, and based on the result of the first determination and the result of the second determination. to control opening and closing of the valve.

According to the present invention, deterioration of the fuel cell stack can be suppressed, and power generation of the fuel cell stack can be stabilized.

FIG. 1 is a schematic configuration diagram of a fuel cell system according to the present invention. FIG. 2 is a partial cross-sectional view of the fuel cell stack. FIG. 3 is a flowchart of wastewater treatment.

[1 Configuration of fuel cell system 10]
FIG. 1 is a schematic configuration diagram of a fuel cell system 10 according to the present invention. The fuel cell system 10 is mounted on a vehicle (fuel cell vehicle). The fuel cell system 10 includes a fuel cell stack 12, a hydrogen tank 14, an anode system 16, a cathode system 18, a cooling system 20, and an output section 21. The fuel cell system 10 also includes a control device 94 .

The fuel cell stack 12 has a plurality of power generation cells 22 stacked in one direction. Each power generation cell 22 has an electrolyte membrane/electrode assembly 24 (also simply referred to as electrode assembly 24) and a set of separators 26, 28. A pair of separators 26 and 28 sandwich the electrode structure 24.

The electrode structure 24 includes a solid polymer electrolyte membrane 30 (also referred to as electrolyte membrane 30), an anode electrode 32, and a cathode electrode 34. The electrolyte membrane 30 is, for example, a thin film of perfluorosulfonic acid containing water. The anode electrode 32 and the cathode electrode 34 sandwich the electrolyte membrane 30 between them. The anode electrode 32 and the cathode electrode 34 have a gas diffusion layer made of carbon paper or the like. An electrode catalyst layer is formed by uniformly applying porous carbon particles to the surface of the gas diffusion layer. A platinum alloy is supported on the surface of the porous carbon particles. Electrode catalyst layers are formed on both sides of the electrolyte membrane 30.

An anode channel 36 is formed on the surface of the separator 26 facing the electrode structure 24 . Anode flow path 36 is connected to anode supply flow path 40 via anode inlet 17A. The anode flow path 36 is connected to the anode discharge flow path 42 via the first anode outlet 17B. Furthermore, the anode flow path 36 is connected to a second drain flow path 48 via the second anode outlet 17C. The second anode outlet 17C is located at a lower position than the first anode outlet 17B. A cathode channel 38 is formed on the surface of the separator 28 facing the electrode structure 24 . Cathode flow path 38 is connected to cathode supply flow path 62 via cathode inlet 19A. Cathode flow path 38 is connected to cathode discharge flow path 64 via cathode outlet 19B.

Anode gas (hydrogen) is supplied to the anode electrode 32 . At the anode electrode 32, hydrogen ions and electrons are generated from hydrogen molecules by an electrode reaction caused by a catalyst. The hydrogen ions pass through the electrolyte membrane 30 and move to the cathode electrode 34. The electrons move in this order to a negative terminal (not shown) of the fuel cell stack 12, a load 104 such as a motor, a positive terminal (not shown) of the fuel cell stack 12, and the cathode electrode 34. At the cathode electrode 34, hydrogen ions and electrons react with oxygen contained in the supplied air due to the action of a catalyst to generate water.

The anode system 16 includes components for supplying anode gas to the anode electrode 32 and components for exhausting anode off-gas from the anode electrode 32. The anode system 16 has an anode supply channel 40 , an anode exhaust channel 42 , a circulation channel 44 , a first drain channel 46 , and a second drain channel 48 . The anode system 16 also includes an injector 50, an ejector 52, a gas-liquid separator 54, a first drain valve 56, a throttle 57, and a second drain valve 58.

The anode supply channel 40 communicates the outlet of the hydrogen tank 14 with the anode inlet 17A. An injector 50 and an ejector 52 are provided in the anode supply channel 40 . Ejector 52 is located closer to anode inlet 17A than injector 50.

The anode discharge channel 42 communicates between the first anode outlet 17B and the intake port of the gas-liquid separator 54. The circulation flow path 44 communicates the exhaust port of the gas-liquid separator 54 and the ejector 52. The first drain channel 46 communicates the drain port of the gas-liquid separator 54 with the inlet of the diluter 60 . A first drain valve 56 is provided in the first drain flow path 46 . The second drain passage 48 communicates the second anode outlet 17C with a portion of the first drain passage 46 downstream of the first drain valve 56. The second drain flow path 48 is provided with a throttle 57 and a second drain valve 58. The throttle 57 is arranged closer to the second anode outlet 17C than the second drain valve 58.

The cathode system 18 includes components for supplying cathode gas to the cathode electrode 34 and components for exhausting cathode off-gas from the cathode electrode 34. Cathode system 18 has a cathode supply channel 62 , a cathode exhaust channel 64 , and a bypass channel 66 . Cathode system 18 also includes a compressor 68 , a humidifier 70 , a first sealing valve 74 , a second sealing valve 76 , and a bypass valve 78 .

The cathode supply channel 62 communicates between an air intake port (not shown) and the cathode inlet 19A. The cathode supply channel 62 is provided with a compressor 68, a first sealing valve 74, and a channel 72A of the humidifier 70. A portion of the cathode supply channel 62 upstream of the humidifier 70 is defined as a cathode supply channel 62A. A portion of the cathode supply channel 62 downstream of the humidifier 70 is defined as a cathode supply channel 62B. A compressor 68 and a first sealing valve 74 are provided in the cathode supply channel 62A. The first sealing valve 74 is located closer to the humidifier 70 than the compressor 68.

The cathode discharge flow path 64 communicates the cathode outlet 19B and the inlet of the diluter 60. A flow path 72B of a humidifier 70 and a second sealing valve 76 are provided in the cathode discharge flow path 64. A portion of the cathode discharge channel 64 upstream of the humidifier 70 is defined as a cathode discharge channel 64A. A portion of the cathode supply channel 62 downstream of the humidifier 70 is defined as a cathode discharge channel 64B. A second sealing valve 76 is provided in the cathode discharge flow path 64B.

Bypass channel 66 communicates cathode supply channel 62A and cathode discharge channel 64B. For example, the bypass passage 66 connects a portion of the cathode supply passage 62A between the compressor 68 and the first sealing valve 74 and a portion downstream of the second sealing valve 76 of the cathode discharge passage 64B. communicate. A bypass valve 78 is provided in the bypass passage 66 .

Anode system 16 and cathode system 18 are connected by a connecting channel 80 . The connecting channel 80 communicates the circulation channel 44 of the anode system 16 with the cathode supply channel 62B of the cathode system 18. A bleed valve 82 is provided in the connection channel 80 .

Cooling system 20 includes components for supplying refrigerant to fuel cell stack 12 and components for discharging refrigerant from fuel cell stack 12 . Cooling system 20 has a refrigerant supply flow path 84 and a refrigerant discharge flow path 86. The cooling system 20 also includes a refrigerant pump 88 and a radiator 90.

A coolant flow path (not shown) for cooling the fuel cell stack 12 is formed inside the fuel cell stack 12 . The coolant supply channel 84 communicates the outlet of the radiator 90 and the inlet of the coolant channel. A refrigerant pump 88 is provided in the refrigerant supply channel 84 . The refrigerant discharge passage 86 communicates the outlet of the refrigerant passage with the inlet of the radiator 90 .

The output unit 21 has various components for supplying electric power to the load 104 included in the vehicle. Output unit 21 includes drive unit 100, power storage device 102, load 104, current sensor 106, and voltage sensor 108.

Drive unit 100 may supply power from fuel cell stack 12 to load 104 . Furthermore, drive unit 100 can supply power from fuel cell stack 12 to power storage device 102 . Further, the drive unit 100 can supply power from the power storage device 102 to the load 104. Furthermore, drive unit 100 can supply power from load 104 to power storage device 102 . The load 104 is, for example, a main engine (travel motor) and an auxiliary machine (vehicle auxiliary machine). Current sensor 106 detects the output current of fuel cell stack 12. Voltage sensor 108 detects the output voltage of fuel cell stack 12.

Control device 94 is a computer (eg, ECU). The control device 94 includes a control section 96 and a storage section 98. The control unit 96 has a processing circuit. The processing circuit may be a processor such as a CPU. The processing circuit may be an integrated circuit such as an ASIC or FPGA. The processor can execute various types of processing by executing programs stored in the storage unit 98. At least some of the plurality of processes may be performed by electronic circuitry including discrete devices.

The control unit 96 controls the operation of the fuel cell system 10. For example, the control unit 96 receives detection signals from various sensors provided in the fuel cell system 10. The control unit 96 outputs control signals for controlling each valve, injector 50, compressor 68, refrigerant pump 88, etc., based on each detection signal. Each valve, injector 50, compressor 68, refrigerant pump 88, etc. operate according to control signals.

Storage unit 98 includes volatile memory and nonvolatile memory. Examples of volatile memory include RAM and the like. Volatile memory is used as the working memory of the processor. Volatile memory temporarily stores data and the like required for processing or calculation. Examples of nonvolatile memory include ROM and flash memory. Non-volatile memory is used as storage memory. Nonvolatile memory stores programs, tables, maps, and the like. At least a portion of the storage unit 98 may be included in a processor, an integrated circuit, or the like as described above.

The nonvolatile memory stores a first threshold value and a second threshold value. The first threshold is a power generation amount threshold for determining whether the vehicle is stopped. For example, the first threshold value is either the maximum amount of power generation when the vehicle is stopped or the minimum amount of power generation when the vehicle is started. The first threshold value can be set in advance based on the power consumption of the auxiliary equipment of the vehicle. The second threshold is a threshold for the amount of water stored in the fuel cell stack 12 (water amount threshold) for determining whether or not to drain water from the fuel cell stack 12. Each of the first threshold value and the second threshold value is set in advance by the user.

[2 Fluid flow]
[2-1 Fluid flow in the anode system 16]
The injector 50 injects anode gas (hydrogen) from the hydrogen tank 14 toward the downstream side of the anode supply channel 40 . The anode gas injected from the injector 50 flows through the anode supply channel 40 and is supplied to the anode channel 36 . The anode gas flows through the anode flow path 36 and is discharged from the first anode outlet 17B as an anode off-gas. The anode off gas includes hydrogen that has not reacted with oxygen, nitrogen in the cathode gas that has passed through the electrolyte membrane 30, and moisture generated by the reaction between oxygen and hydrogen.

The anode off-gas flows through the anode discharge channel 42 and is supplied to the gas-liquid separator 54. The gas-liquid separator 54 separates the anode off-gas into a gas component (anode off-gas) and a liquid component (water). The anode off-gas discharged from the gas-liquid separator 54 flows through the circulation channel 44 and is supplied to the ejector 52. At the ejector 52, the anode off gas and the anode gas injected from the injector 50 merge.

The water separated by the gas-liquid separator 54 is temporarily stored at the bottom of the gas-liquid separator 54. With the first drain valve 56 open, water stored in the gas-liquid separator 54 flows through the first drain channel 46 and is discharged to the diluter 60. When the first drain valve 56 is opened with the water in the gas-liquid separator 54 running out, the anode off-gas in the gas-liquid separator 54 flows through the first drain channel 46 and is discharged to the diluter 60 .

When the inside of the fuel cell stack 12 has high humidity, water is stored at the bottom of the anode channel 36. With the second drain valve 58 open, water stored in the anode channel 36 flows through the second drain channel 48 and the first drain channel 46 and is discharged to the diluter 60. When the second drain valve 58 opens with the water in the anode flow path 36 running out, the anode off-gas in the anode flow path 36 flows through the second drain flow path 48 and the first drain flow path 46 and is discharged to the diluter 60. be done.

[2-2 Fluid flow in cathode system 18]
The compressor 68 discharges cathode gas (air) sucked in from outside the vehicle toward the downstream of the cathode supply channel 62 . With the first sealing valve 74 open, the cathode gas discharged from the compressor 68 flows through the cathode supply channel 62 and is supplied to the cathode channel 38 . The cathode gas flows through the cathode channel 38 and is discharged from the cathode outlet 19B as cathode off-gas. The cathode off-gas includes each component contained in air and moisture generated by the reaction between oxygen and hydrogen.

With the second sealing valve 76 open, the cathode off-gas flows through the cathode discharge channel 64 and is discharged to the diluter 60 . The cathode off gas contains moisture. In the humidifier 70, moisture from the cathode off-gas is used to humidify the cathode gas.

With bypass valve 78 open, cathode gas flows through bypass passage 66 and cathode exhaust passage 64 and is discharged to diluter 60 . The bypass passage 66 is used when reducing the amount of cathode gas supplied to the fuel cell stack 12.

[2-3 Fluid flow in connection channel 80]
With the bleed valve 82 open, a portion of the anode off-gas flowing through the circulation passage 44 flows through the connection passage 80 and is supplied to the cathode supply passage 62B. However, the bleed valve 82 is opened only when the pressure in the anode flow path 36 is higher than the pressure in the cathode flow path 38.

Hydrogen in the anode off-gas flowing through the connection channel 80 and supplied to the cathode supply channel 62B reacts with oxygen on the catalyst of the cathode electrode 34 and is consumed. Therefore, less hydrogen is discharged from the anode system 16 to the outside, and accordingly, the amount of air required to dilute the hydrogen in the diluter 60 is also reduced. Therefore, according to the connection flow path 80, the rotation speed of the compressor 68 that supplies air to the diluter 60 can be lowered, and fuel efficiency is improved. Therefore, the fuel cell system 10 contributes to energy efficiency.

[3 Conditions for wastewater treatment]
FIG. 2 is a partial sectional view of the fuel cell stack 12. As shown in FIG. 2, in this embodiment, each power generation cell 22 is arranged parallel to the up-down direction and the front-back direction. Further, the plurality of power generation cells 22 are stacked in the left-right direction to form a stacked body 22L. An insulator 110R and an end plate 112R are arranged at the right end of the laminate 22L. An insulator 110L and an end plate 112L are arranged at the left end of the laminate 22L. At the rear of the stacked body 22L, flow paths corresponding to the first anode outlet 17B and the second anode outlet 17C are arranged. The flow paths corresponding to the first anode outlet 17B and the second anode outlet 17C extend from right to left. An anode discharge channel 42 is connected to the left side of the end plate 112L. A flow path corresponding to the first anode outlet 17B passes through the end plate 112L and communicates with the anode discharge flow path 42. A second drain channel 48 is connected to the left side of the end plate 112L. A flow path corresponding to the second anode outlet 17C passes through the end plate 112L and communicates with the second drain flow path 48. Although not shown, a flow path corresponding to the anode inlet 17A is arranged in front of the stacked body 22L.

Water accumulates at the bottom of the fuel cell stack 12. In FIG. 2 water is shown as a dot. When the vehicle leans to the right, the fuel cell stack 12 also leans to the right, as shown in FIG. Then, the amount of water flooding into the power generation cell 22 located on the right increases. If this state continues, the fuel cell stack 12 will deteriorate. In order to avoid deterioration of the fuel cell stack 12, it is preferable to drain as much water as possible that accumulates at the bottom of the fuel cell stack 12. Water accumulated in the lower part of the fuel cell stack 12 is discharged to the outside of the fuel cell stack 12 via the second drain passage 48 by opening the second drain valve 58 .

A throttle 57 is provided in the second drain flow path 48 . The pressure upstream of the throttle 57 (inside the fuel cell stack 12) is higher than that downstream of the throttle 57 (outside the fuel cell stack 12). Therefore, when the second drain valve 58 opens, water accumulated inside the fuel cell stack 12 can flow through the second drain passage 48 toward the first drain passage 46 .

On the other hand, when the second drain valve 58 is opened in a state where no water is accumulated in the lower part of the fuel cell stack 12, the anode gas in the anode flow path 36 is discharged to the outside of the fuel cell stack 12. As a result, fuel efficiency deteriorates.

In this embodiment, in order to avoid deterioration of the fuel cell stack 12 and deterioration of fuel efficiency, drain conditions are set in advance, and the second drain valve 58 is opened only when the conditions are met.

It is unlikely that the vehicle will continue to run with the fuel cell stack 12 tilted as shown in FIG. 2 . In other words, it is unlikely that the vehicle will continue to run tilted. For example, if a vehicle drives on a road that slopes to the right, the vehicle will lean to the right. However, it is presumed that road slopes exist locally. Therefore, it is assumed that as the vehicle travels, the tilt of the vehicle returns to the horizontal state in a short period of time. When the fuel cell stack 12 is in a horizontal state, the amount of water flooding into the power generation cell 22 located on the right is small.

On the other hand, when a vehicle stops on a sloped road or parking lot, the vehicle continues to tilt until the vehicle departs. When the vehicle stops tilted to the right, the fuel cell stack 12 continues to be tilted, as shown in FIG. If a large amount of water accumulates in the lower part of the fuel cell stack 12, as described above, the amount of water flooding into the power generation cell 22 located on the right increases.

Therefore, in this embodiment, water is drained from the fuel cell stack 12 when the vehicle is stopped. Furthermore, in this embodiment, when the water accumulated in the fuel cell stack 12 exceeds a threshold value, the fuel cell stack 12 is drained.

[4 Wastewater treatment]
FIG. 3 is a flowchart of wastewater treatment. The control unit 96 repeatedly performs the wastewater treatment shown in FIG. 3 while the fuel cell system 10 is in operation.

In step S1, the control unit 96 calculates the amount of power generation. In this embodiment, the control unit 96 uses the amount of power generation to determine whether the vehicle is stopped. The control unit 96 calculates the amount of power generation (for example, generated power) using, for example, the detected value of the current sensor 106 and the detected value of the voltage sensor 108. When step S1 ends, the process moves to step S2.

In step S2, the control unit 96 determines whether the vehicle is stopped. When the vehicle is stopped, the amount of power generated by the fuel cell stack 12 is below a certain value. The control unit 96 compares the power generation amount calculated in step S1 with a first threshold value (≦constant value). However, the control unit 96 can also determine whether the vehicle is stopped using other sensors provided in the vehicle. Other sensors include a vehicle speed sensor and the like. If the amount of power generation is less than the first threshold, that is, if the vehicle is stopped (step S2: YES), the process moves to step S3. On the other hand, if the amount of power generation is equal to or greater than the first threshold, that is, if the vehicle is not stopped (step S2: NO), the process moves to step S7.

When the process moves from step S2 to step S3, the control unit 96 estimates the amount of water (water storage amount) that has accumulated in the lower part of the fuel cell stack 12 since the vehicle stopped. There is a correlation between the amount of electricity generated and the amount of water produced. Therefore, the control unit 96 can estimate the amount of water stored in the fuel cell stack 12 by acquiring the amount of water corresponding to the amount of power generation at each time and integrating the amount of water. For example, the non-volatile memory of the storage unit 98 stores a map or an arithmetic expression for obtaining the amount of water from the amount of power generation. The control unit 96 estimates the amount of water that can be generated at the present time using the power generation amount calculated in step S1 and the map. Further, the control unit 96 adds the calculated water amount to the latest water storage amount. When step S3 ends, the process moves to step S4.

In step S4, the control unit 96 determines whether or not the fuel cell stack 12 needs to be drained. Specifically, the control unit 96 compares the amount of water stored with a second threshold. If the amount of water stored exceeds the second threshold, that is, if drainage is required (step S4: YES), the process moves to step S5. On the other hand, if the water storage amount is less than or equal to the second threshold, that is, if drainage is not required (step S4: NO), the process moves to step S7.

When the process moves from step S4 to step S5, the control unit 96 opens the second drain valve 58 for a certain period of time. The certain period of time is a period of time during which water in an amount corresponding to the second threshold value can be discharged from the fuel cell stack 12 to the diluter 60 via the second drain channel 48 and the first drain channel 46. When step S5 ends, the process moves to step S6.

In step S6, the control unit 96 initializes the amount of water stored. When step S6 ends, the process moves to step S7.

When the process moves from step S2, step S4, or step S6 to step S7, the control unit 96 closes the second drain valve 58. If the second drain valve 58 is already closed, the control unit 96 maintains the state of the second drain valve 58. On the other hand, if the second drain valve 58 is open, the control unit 96 closes the second drain valve 58.

[5 Invention obtained from embodiment]
The invention that can be understood from the above embodiments will be described below.

A first aspect of the present invention is a fuel cell system (10) for a vehicle, which includes a fuel cell stack (12) that generates electricity using an anode gas and a cathode gas, in which water accumulated at the bottom of the fuel cell stack is removed from the fuel cell stack. a drainage channel (48) connected to the fuel cell stack for discharging water to the outside of the fuel cell stack; and a throttle (57) that makes the upstream side of the drainage channel higher pressure than the downstream side of the drainage channel; It includes a valve (58) that opens and closes the drainage channel, and a control section (96) that controls opening and closing of the valve. The control unit performs a first determination to determine whether the vehicle is stopped, estimates the amount of water accumulated in the lower part of the fuel cell stack based on the amount of power generated by the fuel cell stack, and determines whether the amount of water is the amount of water. A second determination is made to determine whether the amount is greater than or less than a threshold, and opening and closing of the valve is controlled based on the result of the first determination and the result of the second determination.

In the first aspect, the appropriate timing for opening and closing the valve (second drain valve 58) can be determined by performing the first determination (step S2) and the second determination (step S4). Therefore, according to the first aspect, water accumulated in the fuel cell stack can be appropriately drained. Further, according to the first aspect, when the drainage channel is connected to the anode channel, it is possible to suppress the anode gas from being discharged more than necessary. Therefore, according to the first aspect, deterioration of the fuel cell stack can be suppressed, and power generation of the fuel cell stack can be stabilized.

In the above aspect, when determining that the vehicle is stopped in the first determination and determining that the water amount is greater than the water amount threshold in the second determination, the control section You can open the valve.

According to the above configuration, the valve (second drain valve 58) can be opened at an appropriate timing.

In the above aspect, the fuel cell stack includes an anode flow path (36) through which the anode gas flows, and a cathode flow path (38) through which the cathode gas flows, and the drainage flow path is connected to the anode flow path. May be connected.

A second aspect of the present invention is a drainage method for a fuel cell system for a vehicle that includes a fuel cell stack that generates electricity using anode gas and cathode gas. The fuel cell system includes a drainage channel connected to the fuel cell stack for draining water accumulated at the bottom of the fuel cell stack to the outside of the fuel cell stack, and a drainage channel connected upstream of the drainage channel. It includes a throttle that makes the pressure higher than the downstream side of the flow path, a valve that opens and closes the drainage flow path, and a computer (94) that controls the opening and closing of the valve. The computer performs a first determination to determine whether the vehicle is stopped, estimates the amount of water accumulated at the bottom of the fuel cell stack based on the amount of power generated by the fuel cell stack, and determines whether the amount of water is a water amount threshold. A second determination is made to determine whether the amount is greater or less, and opening and closing of the valve is controlled based on the result of the first determination and the result of the second determination.

10...Fuel cell system 12...Fuel cell stack 36...Anode channel 38...Cathode channel 48...Second drain channel (drainage channel) 57...Aperture 58...Second drain valve (valve) 94...Control device (computer) )
96...Control unit

Claims (4)

A fuel cell system for a vehicle comprising a fuel cell stack that generates electricity using anode gas and cathode gas,
a drainage channel connected to the fuel cell stack for draining water accumulated at the bottom of the fuel cell stack to the outside of the fuel cell stack;
a throttle that makes the pressure upstream of the drainage flow path higher than the pressure downstream of the drainage flow path;
a valve that opens and closes the drainage channel;
a control unit that controls opening and closing of the valve;
Equipped with
The control unit includes:
Performing a first determination to determine whether the vehicle is stopped,
Estimating the amount of water accumulated at the bottom of the fuel cell stack based on the amount of power generated by the fuel cell stack,
Performing a second determination to determine whether the water amount is greater than or less than a water amount threshold;
A fuel cell system for a vehicle that controls opening and closing of the valve based on a result of the first determination and a result of the second determination. The fuel cell system for a vehicle according to claim 1,
The control unit opens the valve when determining that the vehicle is stopped in the first determination and determining that the water amount is greater than the water amount threshold in the second determination. Fuel cell system for vehicles. The fuel cell system for a vehicle according to claim 1 or 2,
The fuel cell stack has an anode flow path through which the anode gas flows, and a cathode flow path through which the cathode gas flows,
In a fuel cell system for a vehicle, the drainage flow path is connected to the anode flow path. A drainage method for a fuel cell system for a vehicle equipped with a fuel cell stack that generates electricity using anode gas and cathode gas, the method comprising:
The fuel cell system is
a drainage channel connected to the fuel cell stack for draining water accumulated at the bottom of the fuel cell stack to the outside of the fuel cell stack;
a throttle that makes the pressure upstream of the drainage flow path higher than the pressure downstream of the drainage flow path;
a valve that opens and closes the drainage channel;
a computer that controls opening and closing of the valve;
Equipped with
The computer includes:
Performing a first determination to determine whether the vehicle is stopped,
Estimating the amount of water accumulated at the bottom of the fuel cell stack based on the amount of power generated by the fuel cell stack,
Performing a second determination to determine whether the water amount is greater than or less than a water amount threshold;
A drainage method for a fuel cell system for a vehicle, comprising controlling opening and closing of the valve based on a result of the first determination and a result of the second determination.

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