JP2007317469A - Fuel cell system and fuel cell control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit abnormal pressure in a fuel cell generated by residual hydrogen when operation of a fuel cell system is stopped. <P>SOLUTION: The fuel cell system comprises a fuel cell (1), means (6) for supplying hydrogen to the fuel cell (1), means (14, 15) for supplying air to the fuel cell (1), a battery (5) for storing electric power generated by supplying hydrogen and air to the fuel cell, residual hydrogen consumption means for charging the battery (6) by collecting hydrogen remaining in the fuel cell and supplying air from the supplying means (14, 15) to the collected hydrogen to generate electric power when the fuel cell transits from the electric power generating state to the generation stopping state, and a reserve tank (20) connected to the fuel cell (1) via a valve member (13), wherein in the case that abnormality occurs in the means (14, 15) for supplying air when consuming the residual hydrogen the hydrogen remaining in the fuel cell (1) is received in the reserve tank (20) via the valve member, and the received hydrogen reacts at high temperature and high pressure to produce ammonia. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell system and a control device therefor, and more particularly to a fuel cell system and a fuel cell control device suitable for in-vehicle use.

  FIG. 1 shows a schematic structure of a conventional in-vehicle fuel cell system. In the figure, reference numeral 1 denotes a fuel cell stack, which is constructed by stacking a plurality of fuel cells as is well known. The output of the fuel cell stack 1 is supplied to the vehicle driving motor 3 via the inverter 2 and simultaneously supplied to the battery 5 via the DC / DC converter 4 to charge it.

  The fuel cell system is a system that generates electricity by taking out electrons generated when hydrogen ions and oxygen ions react to generate water, and it is necessary to supply hydrogen and oxygen to the fuel cell stack 1. In FIG. 1, reference numeral 6 denotes a high-pressure hydrogen tank that supplies hydrogen gas to the fuel cell stack 1 via a supply pipe 7. The remaining hydrogen gas that is not used in the fuel cell stack 1 is re-supplied to the supply pipe 7 via the circulation pipe 8 or discharged to the outside via the muffler (not shown). In the figure, 9 is a hydrogen circulation pump, 10 is a backflow prevention valve, 11 is a hydrogen exhaust valve, and 12 and 13 are shut-off valves.

  Oxygen to be reacted with hydrogen gas in the fuel cell stack 1 is taken from the air through an air cleaner (air filter) 14. Reference numeral 15 denotes an air compressor for boosting the intake air. The driving of the pump 9, the air compressor 15 and the respective valve bodies 10 to 13 is controlled by the power supply control unit 16. The power supply control unit 16 starts control by a signal generated by turning on the ignition switch 17.

  In addition, the structure of said general fuel cell system is described in the following patent documents 1 thru | or 3, for example.

JP 2001-35518 A JP 2001-57221 A JP 11-178116 A

  In the conventional fuel cell system, it is necessary to supply air and hydrogen to the fuel cell stack 1 in order to generate power. On the other hand, when power generation is stopped, that is, when the fuel cell system is transitioned from the operating state to the stopped state, the shutoff valves 12 and 13 are closed to stop the supply of hydrogen to the fuel cell stack 1 and the air compressor 15 To stop air intake. Since air is supplied to the cathode side of the fuel cell stack 1, the pressure on the cathode side drops to atmospheric pressure when the air compressor 15 is stopped. On the contrary, since the hydrogen gas pressure is maintained by shutting off the shutoff valves 12 and 13 on the anode side, a pressure difference is generated between the cathode side and the anode side, and stress is applied to the electrolyte membrane in the fuel cell stack 1.

  Therefore, conventionally, as a process when power generation is stopped, hydrogen remaining in the fuel cell stack 1 and the hydrogen pipes 7 and 8 is consumed by reacting with air so that no pressure difference remains in the fuel cell stack 1. Such control is implemented.

  FIG. 2 is a flowchart showing the process of residual hydrogen consumption processing when the operation of the fuel cell system is stopped. For example, when the power supply control unit 16 starts a stop process by turning off the ignition switch 17 (step S1), first, it is detected whether or not there is an abnormality in the air system that is a mechanism on the air intake side (step S2). . Here, if it is determined that there is no abnormality (NO in step S2), the process proceeds to step S3, and air is sent to the fuel cell stack 1 in the normal process. As a result, the remaining hydrogen in the stack and the piping reacts with oxygen in the air to generate electricity, and the generated electricity is stored in the battery 5 (step S4). When the consumption of hydrogen is completed, the stop process is terminated (step S5).

  On the other hand, if it is determined in step S2 that there is an abnormality in the air system, the residual hydrogen consumption process is immediately interrupted (step S6), and the system stop process is terminated as it is (step S5).

  As described above, in the conventional residual hydrogen consumption process, when an abnormality occurs in the air intake system, the hydrogen consumption control is interrupted, so that hydrogen remains in the fuel cell stack 1 and the pipes 7 and 8, and the fuel cell There is a possibility that the parts of the stack 1 and the piping part are always pressurized and the deterioration of the parts is accelerated.

  Moreover, the electric power generated during the hydrogen consumption is supplied to the battery used for assisting the electric power supply during the normal power generation operation and charged. However, if the operation of removing residual hydrogen at the time of full charge is repeated, the battery may be overcharged.

  An object of the present invention is to solve the above-described problems in a conventional fuel cell system.

  In order to solve the above problems, a fuel cell system of the present invention includes a fuel cell, means for supplying hydrogen to the fuel cell, means for supplying air to the fuel cell, the hydrogen to the fuel cell, and A battery for accumulating electric power generated by supplying air, and recovering hydrogen remaining in the fuel cell at the time of transition from an electric power generation state to a generation stop state of the fuel cell; The fuel cell system further includes a means for consuming residual hydrogen to supply power by supplying air from the supply means to charge the battery, and further includes a spare tank connected to the fuel cell via a valve body. When an abnormality occurs in the means for supplying air when the residual hydrogen is consumed, the hydrogen remaining in the fuel cell is stored in the spare tank via the valve body, and Serial is configured to pre-tank accommodating hydrogen reacted at elevated temperature and pressure to produce ammonia.

  The fuel cell control device of the present invention is generated by a fuel cell, means for supplying hydrogen to the fuel cell, means for supplying air to the fuel cell, and supply of the hydrogen and air to the fuel cell At the time of transition from a power generation state of the fuel cell to a generation stop state of the fuel cell, the hydrogen remaining in the fuel cell is recovered, and air is supplied to the recovered hydrogen from the air supply means In the fuel cell control apparatus for controlling the fuel cell system, comprising: a residual hydrogen consuming means for generating electric power and charging the battery; Charge control is performed so that the total charge capacity is equal to or less than a certain value.

  In the fuel cell system according to the present invention, if an abnormality occurs in the air supply means during the residual hydrogen consumption process, the residual hydrogen is accommodated in the reserve tank, so that no pressure abnormality occurs in the fuel cell. Deterioration due to pressurization of the electrolyte membrane and other components in the battery is prevented. Since the hydrogen remaining in the fuel cell contains a nitrogen component, ammonia is generated by maintaining the residual hydrogen at a high temperature and a high pressure. Therefore, residual hydrogen can be converted into ammonia and stored. In addition, since hydrogen is obtained by decomposing ammonia, it can be reused by supplying it to the fuel cell when gas runs out. If not reused, it can be transported to an ammonia treatment plant for treatment.

  According to the fuel cell control device of the present invention, since the charge control at the time of power generation of the fuel cell is controlled so as to be equal to or less than a constant value of the total charge capacity of the battery, the remaining hydrogen consumption is consumed in the remaining portion. The generated power can be stored. This prevents the battery from being overcharged due to residual hydrogen consumption.

  Embodiments of the present invention will be described below with reference to the drawings. Note that, in the following drawings, the same reference numerals as those shown in FIGS. 1 and 2 indicate the same or similar components, and thus a duplicate description will not be given.

Embodiment 1
FIG. 3 shows a schematic configuration of the fuel cell system according to Embodiment 1 of the present invention. As shown in the figure, in the system of this embodiment, a reserve tank 20 is provided on the hydrogen recovery path, and the hydrogen remaining in the fuel cell stack 1 and the hydrogen pipes 7 and 8 when the system operation is stopped is reserved. It collects in the tank 20. As a result, the pressure on the anode side in the fuel cell stack 1 is lowered to balance the pressure with the cathode side to which air is supplied.

  The hydrogen recovered in the reserve tank 20 can be sent to the hydrogen supply pipe 7 by opening the shielding valve 21 and supplied to the fuel cell stack 1. Therefore, when hydrogen is no longer supplied from the normal route, such as when the high-pressure hydrogen tank 6 fails or when the gas in the hydrogen tank 6 is insufficient, the shielding valve 21 is opened and accumulated in the spare tank 20. Electricity is generated using the generated hydrogen as a supplement.

  The hydrogen gas accumulated in the reserve tank 20 can be recovered at the hydrogen station. In this case, for example, a connector provided at the tip of the pipe 22 is connected to the recovery device on the hydrogen station side, the shielding valve 11 is opened, and the hydrogen gas in the reserve tank 20 is moved to the recovery device on the hydrogen station side. As a result, the surplus hydrogen that is not used in the auxiliary power generation can be effectively used.

Embodiment 2
Below, with reference to FIG. 4 and 5, the fuel cell system concerning Embodiment 2 of this application is demonstrated.

  FIG. 4 is a diagram showing a schematic configuration of the fuel cell system according to the present embodiment, and particularly shows a configuration on the air intake side. Note that the hydrogen supply side and the electrical system are not changed from those shown in FIG.

  In FIG. 4, 30 indicates an air intake side system, and 40 indicates an exhaust side system. The intake side system 30 includes an air tank 31, a shielding valve 32, and a compressor 33 in parallel with a conventional intake path including the air cleaner 14 and the compressor 15. The exhaust system 40 is mainly composed of a muffler.

  The operation of the above system will be described with reference to the flowchart of FIG. First, similarly to the conventional flow shown in FIG. 2, when the system stop process is started (step S1), it is detected whether or not there is any abnormality in the air intake side system (step S2). If there is no abnormality (NO in step S2), the processing is the same as in the conventional system, and therefore air is taken into the fuel cell stack 1 via the air cleaner 14 and the compressor 15 in step S3. In the next step S4, when the remaining hydrogen is consumed in the fuel cell stack by the taken-in air and the generated electricity is stored in the battery (step S4), the process ends (step S5).

  On the other hand, if an abnormality is found in the air system in step S2 (YES in step S2), the shielding valve 32 is opened in step S10, and air is supplied from the air tank 31 to the fuel cell stack 1 via the compressor 33. The In step S4, the residual hydrogen consumption process is executed by the air thus supplied. When the process is completed, the system stop process is terminated in step S5.

  As described above, in the present embodiment, by providing a spare air tank on the air intake side of the fuel cell system, it is possible to perform the remaining hydrogen consumption process even when an abnormality occurs in the normal air intake system. Therefore, no pressure abnormality occurs in the fuel cell stack.

Embodiment 3
FIG. 6 is a diagram showing a configuration of the fuel cell system according to Embodiment 3 of the present invention, particularly on the air intake side. Note that the hydrogen supply side and the electrical system are not changed from those shown in FIG.

  In the fuel cell system of the present embodiment, as shown in FIG. 6, when the system for taking in air is divided into two systems and only one system is used for normal system stop processing, when an abnormality occurs in the system, The other system is used to supply air to the fuel cell stack 1. As a result, even when an abnormality occurs in the air system, it is possible to perform the remaining hydrogen consumption process normally.

  In FIG. 6, 14 'is an air cleaner similar to the air cleaner 14, 15' is a compressor similar to the compressor 15, 34 and 35 are shielding valves, and 41 is a muffler.

Embodiment 4
FIG. 7 is a diagram for explaining the configuration of the fourth embodiment of the present invention. In particular, residual hydrogen from the fuel cell stack 1 is diluted by exhausting air from the fuel cell stack 1 and released to the atmosphere. It shows the route to do.

  In the figure, 50 is a radiator fan, 51 is a pump, 52 is a pressure regulating valve for adjusting the exhaust pressure of air from the fuel cell stack 1, 53 is a hydrogen exhaust from the fuel cell stack 1 diluted with air exhaust Shows the piping for dilution to release to the atmosphere. While the air system does not show an abnormality and the normal system stop process is being performed, residual hydrogen is diluted by the exhaust of air introduced into the dilution pipe 53 via the pressure regulating valve 52 and released to the atmosphere.

  However, in such a mechanism, when an abnormality occurs in the air system, the hydrogen dilution air is not supplied to the dilution pipe 53. Therefore, in the present embodiment, as shown in FIG. 7, a mechanism for introducing the air from the radiator fan 50 into the dilution pipe 53 via the shielding valve 54 is provided. Note that when the shielding valve 54 is opened, the pressure regulating valve 52 is closed.

  Since the release of hydrogen into the atmosphere is dangerous, as a condition for opening the shielding valve 54 and diluting and releasing hydrogen, an abnormality occurs in the air system, and the fan voltage or vehicle speed condition is greater than the set threshold value. When these conditions are satisfied, diluted hydrogen is released to the atmosphere using the air from the radiator fan 50.

  Furthermore, a condition that hydrogen dilution is performed only when there is no person near the vehicle may be added. That is, after confirming that there is no person in the vicinity of the vehicle using a sensor or GPS, hydrogen dilution is performed to release it to the atmosphere. When a person is present in the vicinity of the vehicle, for example, hydrogen may be stored in the reserve tank 20 illustrated in FIG. 3, and hydrogen dilution may be performed after the person is no longer present so as to be released into the atmosphere.

Embodiment 5
FIG. 8 shows a schematic configuration of the residual hydrogen consumption mechanism of the fuel cell system according to Embodiment 5 of the present invention. When there is an abnormality in the air system, the hydrogen remaining in the fuel cell stack 1 is stored in the combustion tank 54 and supplied with oxygen from the reserve oxygen tank 55 for combustion. The heat generated by the combustion is used for heating the interior of the vehicle or for increasing the temperature of the parts. Note that the reserve tank 20 of FIG. 3 may be used as the combustion tank 54.

Embodiment 6
FIG. 9 is a flowchart for explaining the configuration of the sixth embodiment of the present invention. In the present embodiment, when there is an abnormality in the air system, hydrogen remaining in the fuel cell stack is moved to another tank, and ammonia is generated in this tank, so that hydrogen is consumed. That is, in the flowchart of FIG. 9, if it is determined in step S2 that there is an abnormality in the air system (YES in step S2), the residual hydrogen in the fuel cell stack is moved to another tank in step S20, and the tank is stored in step S21. The inside is set to 500 ° C. and 600 atm to generate ammonia.

  Since nitrogen atoms and hydrogen atoms are almost the same size, nitrogen and hydrogen exist in the hydrogen side stack of the fuel cell stack as nitrogen in the atmosphere permeates the membrane in the stack. Accordingly, the hydrogen recovered in the separate tank as residual hydrogen contains nitrogen atoms, and ammonia is generated by reacting these under high temperature and high pressure.

  If the generated ammonia is full in the tank (YES in step S22), the ammonia generated in step S23 is released to the atmosphere, and the process ends in step S5. On the other hand, when it is determined in step S22 that the tank is not full (NO in step S22), the process is continued, and the generated ammonia is transported to the ammonia treatment plant (step S24).

Other Embodiments The problem that the battery is overcharged due to the power generated during the consumption process of the remaining hydrogen is to perform charge control so that the amount of charge during normal operation is not more than a certain value of the capacity of the battery, Can be solved.

  FIG. 10 is a diagram for illustrating the charging control of the battery in the present embodiment. As shown in the figure, the full charge capacity of the battery 5 is divided into a charge area by normal system operation and an area used by residual hydrogen consumption, so that full charge does not occur in normal system operation. This makes it possible to prevent overcharging of the battery due to consumption of residual hydrogen.

  Furthermore, although not shown, the problem of battery overcharging can also be solved by providing a battery for consuming residual hydrogen separately from the normal battery 5.

The figure which shows schematic structure of the conventional fuel cell system. The flowchart of the stop process in the conventional fuel cell system. 1 is a diagram showing a schematic configuration of a fuel cell system according to Embodiment 1 of the present invention. The figure which shows schematic structure of the fuel cell system concerning Embodiment 2 of this invention. The flowchart of the stop process in the system shown in FIG. The figure which shows schematic structure of the fuel cell system concerning Embodiment 3 of this invention. The figure which shows schematic structure of the fuel cell system concerning Embodiment 4 of this invention. The figure which shows schematic structure of the fuel cell system concerning Embodiment 5 of this invention. The figure which shows the operation | movement flow of the fuel cell system concerning Embodiment 6 of this invention. The figure which shows the charge capacity of the battery concerning other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell stack 3 Motor 5 Battery 6 High pressure hydrogen tank 7, 8 Hydrogen piping 9 Pump 10, 11, 12, 13 Valve body 14 Air cleaner 15 Air compressor 20 Spare tank 31 Air tank 33 Compressor 41 Muffler 50 Radiator fan 51 Pump 53 For dilution Piping 54 Tank for combustion 55 Reserve oxygen tank

Claims (2)

A fuel cell;
Means for supplying hydrogen to the fuel cell;
Means for supplying air to the fuel cell;
A battery that stores electrical power generated by the supply of hydrogen and air to the fuel cell;
At the time of transition from the power generation state of the fuel cell to the generation stop state, hydrogen remaining in the fuel cell is recovered, and air is supplied to the recovered hydrogen from the air supply means to generate electric power. A fuel cell system comprising a means for consuming residual hydrogen to charge a battery,
Furthermore, a reserve tank connected to the fuel cell via a valve body is provided,
When an abnormality occurs in the means for supplying air when the residual hydrogen is consumed, the hydrogen remaining in the fuel cell is stored in the spare tank via the valve body, and the hydrogen stored in the spare tank is stored. A fuel cell system characterized in that ammonia is produced by reacting at high temperature and high pressure. A fuel cell;
Means for supplying hydrogen to the fuel cell;
Means for supplying air to the fuel cell;
A battery that stores electrical power generated by the supply of hydrogen and air to the fuel cell;
At the time of transition from the power generation state of the fuel cell to the generation stop state, hydrogen remaining in the fuel cell is recovered, and air is supplied to the recovered hydrogen from the air supply means to generate electric power. A fuel cell control device for controlling a fuel cell system, comprising: means for consuming residual hydrogen for charging a battery;
The fuel cell control device according to claim 1, wherein the battery is charged so that a charge amount at the time of generating power of the fuel cell is equal to or less than a predetermined value of a total charge capacity of the battery.

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