JP2004119122A - Hydrogen cutoff device of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the solid high polymer electrolyte film of a fuel cell from being applied with excessive stress when hydrogen supply is cut off by something abnormal. <P>SOLUTION: This hydrogen cutoff device of the fuel cell 1 is provided with a hydrogen supply passage 21 to supply hydrogen to the solid high polymer electrolyte film type fuel cell 1, a hydrogen cutoff valve 4 to cut off hydrogen supplied to the fuel cell 1 provided in the hydrogen supply passage 21 when something abnormal occurs, a hydrogen storage tank 7 which is disposed on the downstream of the hydrogen cutoff valve 4 and is capable of introducing hydrogen supplied to the fuel cell, and a hydrogen exhaust valve 6 to allow introduction of hydrogen into the hydrogen storage tank 7 by opening when something abnormal occurs. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell hydrogen shutoff device that shuts off hydrogen supply to a fuel cell when an abnormality occurs.
[0002]
[Prior art]
A fuel cell is provided with an anode and a cathode on both sides of a solid polymer electrolyte membrane, supplies hydrogen as a fuel to the anode, and supplies air as an oxidant to the cathode, and performs a redox reaction of these gases. In some cases, chemical energy is directly extracted as electric energy.
In a fuel cell vehicle in which a fuel cell of this type is mounted on a vehicle and drives the drive motor with electric power obtained by power generation of the fuel cell to run the vehicle, a fuel which is a flammable gas at the time of an abnormality such as a collision is used. In order to prevent the hydrogen from being discharged out of the vehicle, the emergency shutoff valve provided in the hydrogen supply channel is closed to shut off the hydrogen supply channel. (For example, see Patent Document 1).
[0003]
[Patent Document 1]
JP 2001-119815 A (paragraph numbers [0006] and [0037])
[0004]
[Problems to be solved by the invention]
However, in the conventional emergency response, when the abnormality is detected, the hydrogen supply system shuts off the hydrogen supply from the high-pressure hydrogen tank by closing the emergency shutoff valve, but the positive pressure hydrogen flows in the flow path downstream of the emergency shutoff valve. Remains. On the other hand, in the air supply system, when an abnormality is detected, the supply of air is stopped, and the pressure in the air system is immediately reduced to about atmospheric pressure. Therefore, there is a problem that an excessive pressure difference between the anode and the cathode of the fuel cell is generated, and an excessive stress is applied to the solid polymer electrolyte membrane.
Therefore, the present invention provides a hydrogen shutoff device for a fuel cell that can protect the fuel cell when the hydrogen supply line is shut off in an abnormal situation.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a hydrogen supply flow path (for example, hydrogen in an embodiment described later) for supplying hydrogen to a fuel cell (for example, a fuel cell 1 in an embodiment described later). A fuel supply system comprising: a supply flow path 21); and a hydrogen shutoff means (for example, a hydrogen shutoff valve 4 in an embodiment described later) provided in the hydrogen supply flow path and shutting off hydrogen supplied to the fuel cell when an abnormality occurs. A hydrogen storage device (for example, a hydrogen storage tank 7 according to an embodiment described later) that is capable of introducing hydrogen supplied to the fuel cell downstream of the hydrogen shutdown device, Opening / closing means (for example, a hydrogen discharge valve 6 in an embodiment described later) which is opened to permit introduction of hydrogen into the hydrogen storage means.
With this configuration, the opening / closing unit is opened in the event of an abnormality, so that the hydrogen supplied to the fuel cell downstream of the hydrogen shutoff unit and supplied to the fuel cell is introduced into the hydrogen storage unit, and the downstream of the hydrogen shutoff unit. Hydrogen pressure can be reduced. As a result, the pressure difference between the anode and the cathode of the fuel cell can be reduced.
[0006]
According to a second aspect of the present invention, in the first aspect, the hydrogen storage means is a tank containing a hydrogen storage alloy.
With this configuration, in the event of an abnormality, it is possible to cause the hydrogen storage alloy to store the hydrogen supplied to the fuel cell downstream of the hydrogen shutoff means, and to reliably retain the stored hydrogen. it can.
[0007]
According to a third aspect of the present invention, in the first or second aspect of the present invention, when the hydrogen pressure downstream of the hydrogen shut-off means falls below a predetermined pressure after the opening / closing means is opened, The opening and closing means is closed.
With this configuration, it is possible to reliably reduce the pressure of hydrogen downstream of the hydrogen shut-off means to the predetermined pressure or less when an abnormality occurs.
[0008]
The invention according to claim 4 provides a hydrogen supply channel (for example, a hydrogen supply channel 21 in an embodiment described later) that supplies hydrogen to a fuel cell (for example, a fuel cell 1 in an embodiment described below), A hydrogen shutoff means (for example, a hydrogen shutoff valve 4 in an embodiment described later) provided in the hydrogen supply flow path, and returns the hydrogen discharged from the fuel cell to the hydrogen supply flow path downstream of the hydrogen cutoff means. A hydrogen circulation channel (for example, a hydrogen circulation channel 23 in an embodiment described later) for circulating the fuel into the fuel cell, and a hydrogen storage unit (for example, an embodiment described later) capable of introducing hydrogen provided in the hydrogen circulation channel. And a hydrogen storage tank 7) according to the first aspect of the present invention, wherein the hydrogen shutoff means is shut off when an abnormality occurs, and the hydrogen pressure in the hydrogen circulation flow path is reduced by the hydrogen storage means. The hydrogen shut-off device for a fuel cell characterized by reduced to a predetermined pressure.
With this configuration, it is possible to close the hydrogen circulation channel by shutting off the hydrogen shutoff unit when an abnormality occurs, and prevent the hydrogen in the hydrogen circulation channel from being released to the outside by the hydrogen storage unit. Thus, the hydrogen pressure in the hydrogen circulation channel can be reduced to a predetermined pressure, and the pressure difference between the anode and the cathode of the fuel cell can be reduced.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a hydrogen cutoff device for a fuel cell according to the present invention will be described with reference to the drawings of FIGS. The embodiment described below is an embodiment of a hydrogen cutoff device for a fuel cell mounted on a fuel cell vehicle.
FIG. 1 is a schematic configuration diagram of a fuel cell system including a hydrogen cutoff device.
The fuel cell 1 is composed of a stack formed by stacking a plurality of cells formed by sandwiching a solid polymer electrolyte membrane made of, for example, a solid polymer ion exchange membrane between an anode and a cathode from both sides. When air containing oxygen as an oxidant is supplied to the cathode, the hydrogen ions generated by the catalytic reaction at the anode pass through the solid polymer electrolyte membrane to the cathode, and undergo electrochemical reaction with oxygen at the cathode. And water is generated.
[0010]
The hydrogen stored in the high-pressure hydrogen tank 2 as the hydrogen supply means flows through the hydrogen supply flow path 21 provided with the pressure regulating valve 3, the hydrogen cutoff valve (hydrogen cutoff means) 4, and the ejector 5, and It is supplied to the anode of each cell. The pressure adjusting valve 3 is for reducing the pressure of the hydrogen in the high-pressure hydrogen tank 2 to a predetermined pressure. The hydrogen shutoff valve 4 is provided in the hydrogen supply flow path 21 and shuts off the supply of hydrogen to the downstream flow path. The ejector 5 is for returning a hydrogen off-gas described later discharged from the fuel cell 1 to the hydrogen supply flow path 21. In some cases, a pump is used instead of the ejector 5. Further, a pressure sensor 12 for detecting hydrogen pressure is provided in a hydrogen supply flow path 21 downstream of the ejector 5.
[0011]
Among the hydrogen supplied to the anode of the fuel cell 1, hydrogen that has not been used for power generation, that is, unreacted hydrogen, is discharged from the fuel cell 1 as hydrogen off-gas, and is drawn into the ejector 5 through the hydrogen off-gas flow path 22. And the fresh hydrogen supplied from the high-pressure hydrogen tank 2 is supplied to the anode of the fuel cell 1 again. That is, the hydrogen (hydrogen off gas) discharged from the fuel cell 1 is returned to the hydrogen supply flow path 21 downstream of the hydrogen shutoff valve 4 through the hydrogen off gas flow path 22 and circulated to the fuel cell 1. Here, the hydrogen supply passage 21 and the hydrogen off-gas passage 22 located downstream of the hydrogen shutoff valve 4 constitute a hydrogen circulation passage 23.
[0012]
The hydrogen off-gas flow path 22 constituting a part of the hydrogen circulation flow path 23 is connected to the hydrogen storage tank 7 by a hydrogen discharge flow path 24 having a hydrogen discharge valve (opening / closing means) 6. The hydrogen discharge valve 6 is normally closed during normal operation to prevent the hydrogen in the hydrogen circulation passage 23 from being introduced into the hydrogen storage tank 7, and is opened when an abnormality such as a collision of a vehicle occurs and the hydrogen circulation passage 23 is opened. Is allowed to be introduced into the hydrogen storage tank 7. The hydrogen storage tank 7 is a closed container containing a hydrogen storage alloy therein, and the hydrogen storage alloy is an alloy having a function of storing and releasing hydrogen under predetermined conditions, as is well known.
[0013]
On the other hand, the air is pressurized to a predetermined pressure by the compressor 8 and supplied to the cathode of the fuel cell 1 through the air passage 31. After the air supplied to the fuel cell 1 is used for power generation, the air is discharged from the fuel cell 1 to the air off-gas flow path 32 as air off-gas, and is discharged via the pressure control valve 9.
Further, the vehicle is provided with an impact sensor (abnormality detecting means) 11 for detecting the magnitude (impact value) of the impact applied to the vehicle. Output signals of the shock sensor 11 and the pressure sensor 12 are input to an electronic control unit (ECU) 10, which controls the opening and closing of the hydrogen shutoff valve 4 and the hydrogen discharge valve 6 based on the output signals of the sensors 11 and 12. I do.
[0014]
In the fuel cell system configured as described above, when the impact value detected by the impact sensor 11 is equal to or less than a predetermined value, the ECU 10 determines that there is no abnormality, and holds the hydrogen shutoff valve 4 open, The closed state of the hydrogen discharge valve 6 is maintained. Thereby, the hydrogen in the high-pressure hydrogen tank 2 and the hydrogen off-gas discharged from the fuel cell 1 can be supplied to the fuel cell 1 at a predetermined pressure, and the fuel cell 1 is maintained in a state capable of generating power.
[0015]
On the other hand, when the shock value detected by the shock sensor 11 exceeds the predetermined value, the ECU 10 determines that there is an abnormality, and closes the hydrogen cutoff valve 4 and opens the hydrogen discharge valve 6. By closing the hydrogen shutoff valve 4, the hydrogen in the high pressure hydrogen tank 2 is prevented from flowing into the hydrogen supply flow path 21 downstream of the hydrogen shutoff valve 4, and the hydrogen circulation flow path 23 is separated from the high pressure hydrogen tank 2. Will be shut off. When the hydrogen discharge valve 6 is opened, hydrogen of a predetermined pressure confined in the hydrogen circulation flow path 23 is introduced into the hydrogen storage tank 7 through the hydrogen discharge flow path 24, and the hydrogen storage tank The hydrogen is stored in the hydrogen storage alloy housed in 7. When the hydrogen in the hydrogen circulation channel 23 is introduced into the hydrogen storage tank 7, the pressure in the hydrogen circulation channel 23 decreases. Then, when the pressure detected by the pressure sensor 12 falls below a predetermined set pressure, the hydrogen discharge valve 6 is closed.
[0016]
Thus, in the event of an abnormality when a large impact is applied to the vehicle, the hydrogen present in the hydrogen circulation channel 23 can be discharged to the hydrogen storage tank 7 without being released outside the vehicle. Further, by discharging the hydrogen in the hydrogen circulation channel 23, the pressure in the hydrogen circulation channel 23 can be reduced. In particular, in this embodiment, the hydrogen discharge valve 6 is closed when the pressure in the hydrogen circulation flow path 23 falls below the set pressure. The pressure can be reduced to the following. Therefore, when the fuel cell system is stopped thereafter, the pressure difference between the anode and the cathode of the fuel cell 1 can be reduced. As a result, it is possible to prevent an excessive stress from being applied to the solid polymer electrolyte membrane after the system is stopped, and to protect the fuel cell 1.
[0017]
In order to quickly move the hydrogen in the hydrogen circulation channel 23 into the hydrogen storage tank 7 when the hydrogen discharge valve 6 is opened, the hydrogen storage alloy in the hydrogen storage tank 7 must be activated in advance. In addition, it is preferable that a dehydrogenation process is performed, and further, the pressure in the hydrogen storage tank 7 is reduced, and an inert gas is sealed in the hydrogen storage tank 7.
[0018]
Further, the hydrogen storage alloy has a property that heat is taken in and out of the storage and release of hydrogen, generates heat by hydrogenation reaction of the hydrogen storage alloy when storing hydrogen, and absorbs heat when releasing hydrogen. Therefore, as the hydrogen storage alloy to be stored in the hydrogen storage tank 7, a hydrogen storage alloy having a low hydrogen storage pressure (hydrogen storage equilibrium pressure) even at a high temperature can be used even if the temperature of the hydrogen storage alloy becomes high due to heat generated by the hydrogen storage. It is preferable because it has the ability to absorb hydrogen. In addition, when a hydrogen storage alloy having a low hydrogen storage pressure even at such a high temperature is used, a higher temperature is required to release hydrogen from the hydrogen storage alloy, so that once stored hydrogen is hardly released from the hydrogen storage alloy. There is also an advantage.
[0019]
Next, the hydrogen cutoff control of the fuel cell according to this embodiment will be described with reference to the flowchart of FIG.
The flowchart shown in FIG. 2 shows a hydrogen cutoff control routine. The hydrogen cutoff control routine is executed by the ECU 10. The hydrogen cutoff control is executed by using an ON signal of an ignition switch as a trigger.
[0020]
When the ignition switch ON signal is detected in step S101, the process proceeds to step S102, and it is determined whether the ignition switch is turned off.
If the result of the determination in step S102 is "YES" (ignition SW OFF), the process proceeds to step S108, in which the fuel cell system is stopped, and the execution of this routine ends.
If the determination result in step S102 is “NO” (ignition SW ON), the process proceeds to step S103, and it is determined whether or not the shock value detected by the shock sensor 11 is equal to or greater than a predetermined threshold value.
If the determination result in step S103 is "NO" (impact value <threshold value), it is determined that there is no abnormality, and the process proceeds to step S104, where the hydrogen shutoff valve 4 is kept open and the hydrogen discharge valve 6 is closed. To maintain.
[0021]
On the other hand, if the result of the determination in step S103 is “YES” (impact value ≧ threshold), it is determined that there is an abnormality, and the process proceeds to step S105, where the hydrogen shutoff valve 4 is closed and the hydrogen discharge valve 6 is opened. At the same time, the compressor 8 is stopped.
Next, the process proceeds to step S106, and it is determined whether or not the pressure in the hydrogen circulation channel 23 detected by the pressure sensor 12 is equal to or less than a preset value.
If the result of the determination in step S106 is "NO" (pressure in the hydrogen circulation flow path> set value), the pressure in the hydrogen circulation flow path 23 is still high, so the flow returns to step S105 and the hydrogen shutoff valve 4 is closed. While maintaining the state, the hydrogen discharge valve 6 is maintained in the open state.
[0022]
If the result of the determination in step S106 is “YES” (pressure in the hydrogen circulation flow path ≦ set value), the pressure in the hydrogen circulation flow path 23 has been sufficiently reduced, so the flow proceeds to step S107 and the hydrogen discharge valve 6 is closed.
Thereafter, the process proceeds to step S108, in which the fuel cell system is stopped, and the execution of this routine ends.
[0023]
[Other embodiments]
Note that the present invention is not limited to the above-described embodiment.
For example, in the above-described embodiment, the time when a large impact is applied to the vehicle is regarded as an abnormal condition and the hydrogen shutoff valve 4 is closed and the hydrogen discharge valve 6 is opened. However, the present invention is not limited to this. Determines that the case where the hydrogen concentration exceeds a predetermined threshold value in a predetermined region of the vehicle having a low hydrogen concentration is abnormal, and closes the hydrogen cutoff valve 4 and opens the hydrogen discharge valve 6 as in the above-described embodiment. It may be. In such a case, a hydrogen sensor is installed in the predetermined area, and when the detection value of the hydrogen sensor exceeds a threshold value, it is determined that there is an abnormality.
[0024]
Further, in the above-described embodiment, the hydrogen discharge valve 6 opened by the abnormality detection is closed when the pressure in the hydrogen circulation channel 23 becomes equal to or less than the set value. May be detected, and the hydrogen discharge valve 6 may be closed when the pressure difference between the electrodes becomes equal to or less than the threshold value.
Further, in the above-described embodiment, the hydrogen storage unit is configured by the tank containing the hydrogen storage alloy, but the hydrogen storage unit may be configured by a simple tank. In that case, the tank is preferably filled with an inert gas.
[0025]
【The invention's effect】
As described above, according to the first aspect of the invention, in the event of an abnormality, the opening / closing means is opened, and the hydrogen supplied to the fuel cell downstream of the hydrogen shutoff means and supplied to the fuel cell is introduced into the hydrogen storage means. Since the pressure of hydrogen downstream of the shut-off means can be reduced, the pressure difference between the anode and the cathode of the fuel cell can be reduced when the fuel cell system is stopped due to an abnormality. An excellent effect of being able to protect is achieved.
[0026]
According to the second aspect of the present invention, in the event of an abnormality, hydrogen supplied to the fuel cell downstream of the hydrogen shutoff means can be stored in the hydrogen storage alloy, and the stored hydrogen is securely retained. Therefore, there is an effect that release of hydrogen can be reliably prevented.
According to the invention according to claim 3, the pressure of hydrogen downstream of the hydrogen shut-off means can be reliably reduced to the predetermined pressure or less at the time of abnormality, so that the fuel cell can be reliably stopped when the fuel cell system is stopped due to the abnormality. There is an effect that it can be protected.
[0027]
According to the invention according to claim 4, the hydrogen circulation passage can be closed by shutting off the hydrogen interruption unit in the event of an abnormality, and the hydrogen in the hydrogen circulation passage is released to the outside by the hydrogen storage unit. The hydrogen pressure in the hydrogen circulation channel can be reduced to a predetermined pressure without causing the pressure difference between the anode and the cathode of the fuel cell to be reduced. In addition, an excellent effect is provided that the fuel cell can be protected when the fuel cell system is stopped due to an abnormality.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment of a fuel cell system including a hydrogen cutoff device according to the present invention.
FIG. 2 is a flowchart showing hydrogen cutoff control in the embodiment.
[Explanation of symbols]
1 fuel cell 4 hydrogen shutoff valve (hydrogen shutoff means)
6 Hydrogen discharge valve (opening / closing means)
7. Hydrogen storage tank (hydrogen storage means)
21 Hydrogen supply channel 23 Hydrogen circulation channel

Claims (4)

A hydrogen supply device for supplying hydrogen to a fuel cell, and a hydrogen cutoff device provided in the hydrogen supply flow passage and configured to shut off hydrogen supplied to the fuel cell when an abnormality occurs.
Hydrogen storage means capable of introducing hydrogen supplied to the fuel cell downstream of the hydrogen cutoff means,
Opening / closing means which is opened at the time of an abnormality to permit introduction of hydrogen into the hydrogen storage means,
A hydrogen cutoff device for a fuel cell, comprising: The hydrogen shutoff device for a fuel cell according to claim 1, wherein the hydrogen storage means is a tank containing a hydrogen storage alloy. 3. The opening / closing unit according to claim 1, wherein the opening / closing unit is closed when a hydrogen pressure downstream of the hydrogen shutoff unit becomes lower than a predetermined pressure after the opening / closing unit is opened. Fuel cell hydrogen shut-off device. A hydrogen supply flow path for supplying hydrogen to the fuel cell, a hydrogen cutoff means provided in the hydrogen supply flow path, and returning hydrogen discharged from the fuel cell to the hydrogen supply flow path downstream of the hydrogen cutoff means. A hydrogen circulation channel circulating through the fuel cell, and a hydrogen storage means provided in the hydrogen circulation channel and capable of introducing hydrogen, a hydrogen cutoff device for a fuel cell,
A hydrogen shutoff device for a fuel cell, wherein the hydrogen shutoff means is shut off when an abnormality occurs, and the hydrogen pressure in the hydrogen circulation channel is reduced to a predetermined pressure by the hydrogen storage means.

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