JP3721596B2 - Vehicle fuel cell control device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a fuel cell control device for a vehicle equipped with a fuel cell that generates an electromotive force by supplying fuel gas to an electrode.
[0002]
[Prior art]
In recent years, vehicles using a fuel cell as a power source for a motor that operates in place of an in-vehicle internal combustion engine have been put into practical use. In this fuel cell, a pair of electrodes including a catalyst is usually disposed on both sides of an electrolyte membrane, a fuel gas such as hydrogen is brought into contact with the surface of one electrode, and oxygen containing oxygen is formed on the surface of the other electrode. The contained gas is brought into contact, and electric energy is taken out between the electrodes by utilizing an electrochemical reaction that occurs at this time.
[0003]
The fuel gas supplied to the fuel cell is generally generated by a reformer. According to the steam reforming of methanol performed by the reformer, carbon monoxide (CO) is generated by a chemical reaction, and this CO is adsorbed to platinum or an alloy containing platinum as an electrode catalyst on the fuel electrode side, This causes a so-called catalyst poisoning state to be stopped. For this reason, this type of fuel cell needs to be configured to reduce CO in the gas from the reformer, which is a major problem.
[0004]
As a method for solving this problem, there has been proposed a technique for oxidizing CO to change to CO ₂ by introducing air or oxygen into the fuel gas from the reformer (Japanese Patent Laid-Open No. 5-21080). ). According to this technique, CO poisoning of the hydrogen electrode catalyst is prevented, and good power generation is maintained.
[0005]
[Problems to be solved by the invention]
By the way, these conventional techniques are only for stationary systems. Actually, when this technique is applied to a vehicle such as an electric vehicle, the above-mentioned technique is not performed when the vehicle is stopped so as not to adversely affect the driving state of the vehicle. It was necessary to perform control, that is, control for introducing air or oxygen into the fuel gas. For this purpose, a special configuration for detecting the stop of the vehicle is required, which causes a problem of an increase in the number of parts.
[0006]
The fuel cell control device for a vehicle according to the present invention has been made in view of such problems, and it is possible to realize a countermeasure for electrode poisoning of the fuel cell in a vehicle-mounted system and to suppress an increase in the number of parts. It is aimed.
[0007]
[Means for Solving the Problems]
In order to achieve such an object, the following configuration was adopted as means for solving the above-described problems.
[0008]
That is, the vehicle fuel cell control device of the present invention is
A vehicle,
A reformer mounted on the vehicle and generating fuel gas;
Mounted on the vehicle, a fuel cell control device for a vehicle with a supplied with the fuel gas to the electrode with a catalytic fuel cell generates an electromotive force,
Fuel gas supply means for supplying the fuel gas to the electrode of the fuel cell;
Oxygen-containing gas introduction means for introducing an oxygen-containing gas into the fuel gas;
An operation switch that is operated by a driver of the vehicle to control operation / stop of the vehicle;
The operation switch is characterized in that a gas introducing actuation means for actuating the said oxygen-containing gas introduction unit immediately when it is switched to the stop state from the operating state.
[0009]
[Action]
According to the fuel cell control apparatus for a vehicle configured as described above, immediately when the operation switch is switched from the operation state to the stop state, the gas introduction actuating means actuates the oxygen-containing gas introducing means. As a result, an oxygen-containing gas is introduced into the fuel gas, and the carbon monoxide adhering to the electrode is oxidized by the oxygen-containing gas to change to carbon dioxide, and is peeled off from the electrode surface. Therefore, the electrode catalyst is reactivated and poisoning is eliminated. In addition, since the operation timing of the oxygen-containing gas introduction means is immediately when the operation switch is switched from the operation state to the stop state, it is necessary to newly provide a special configuration for detecting the stop of the vehicle in the vehicle. There is no.
[0010]
【Example】
In order to further clarify the configuration and operation of the present invention described above, preferred embodiments of the present invention will be described below.
[0011]
FIG. 1 is a schematic configuration diagram of a fuel cell control system 1 for a vehicle according to a first embodiment of the present invention, and FIG. 2 is a structural diagram showing a single cell of a fuel cell 10. Here, before describing the entire fuel cell control system 1 of the vehicle, the configuration of the fuel cell 10 used therein will be described first.
[0012]
The fuel cell 10 is a polymer electrolyte fuel cell, and as shown in FIG. 2, as a single cell, an electrolyte membrane 11 and a gas diffusion electrode having a sandwich structure sandwiching the electrolyte membrane 11 from both sides. Cathode 12 and anode 13, and current collector 15 as a flow path forming member that forms a flow path of oxygen-containing gas and hydrogen-containing gas with cathode 12 and anode 13 while sandwiching this sandwich structure from both sides. ing.
[0013]
The electrolyte membrane 11 is an ion exchange membrane having a thickness of 50 [μm] to 200 [μm] formed of a polymer material, for example, a fluorine resin, and exhibits good electrical conductivity in a wet state. Here, the trade name Nafion 115 manufactured by EI DuPont, USA is used. The cathode 12 and the anode 13 are formed of a carbon cloth woven with yarns in which carbon fibers whose surfaces are coated with polytetrafluoroethylene and carbon fibers not treated at all are in a ratio of 1: 1. Since the polytetrafluoroethylene exhibits water repellency, the cathode 12 and the anode 13 are covered with water so that the permeation of gas is not hindered. On the surface of the carbon cloth on the electrolyte membrane 11 side and in the gap, carbon powder carrying platinum or an alloy made of platinum and other metals is kneaded to form a catalytic reaction layer.
[0014]
Specifically, as the carbon powder carrying platinum, a platinum powder having a weight of 40 [%] (% by weight) with respect to the weight of the carbon powder is used. Catalytic reaction by adding and mixing a fluorine-based cation exchange resin solution (Nafion solid content 5 [%]) in an amount corresponding to 50 [%] resin solid content with respect to the amount of mg / cm ² ]. A layer is formed.
[0015]
The electrolyte membrane 11, the cathode 12 and the anode 13 have a sandwich structure in which both the electrodes 12 and 13 are sandwiched between the electrolyte membranes 11 at a temperature of 100 ° C. to 160 ° C., preferably 110 ° C. to 130 ° C., and 1 MPa {10 .2 kgf / cm ² } to 20 MPa {102 kgf / cm ² }, preferably 5 MPa {51 kgf / cm ² } to 10 MPa {102 kgf / cm ² }.
[0016]
The current collector 15 is formed of a dense carbon plate. A plurality of ribs are formed on the current collector 15, and a straight gas flow path 17 having a rectangular cross section is formed by the ribs and the surfaces of the gas diffusion electrodes. The current collector 15 on the side in contact with the cathode 12 forms an oxygen-containing gas channel 17 a that forms a channel for oxygen-containing gas with the surface of the cathode 12 and also collects water generated by the cathode 12. The current collector 15 on the side in contact with the anode 13 forms a hydrogen-containing gas flow path 17 b that forms a flow path of a mixed gas of hydrogen gas and water vapor, which is a hydrogen-containing gas, with the surface of the anode 13.
[0017]
The electrolyte membrane 11, cathode 12, anode 13 and current collector 15 described above have a single cell configuration of the fuel cell 10. In practice, the current collector 15, cathode 12, electrolyte membrane 11, anode 13, current collector The fuel cell 10 is configured by stacking a plurality of sets of electric bodies 15 in this order and arranging a collecting electrode (not shown) on the outside thereof.
[0018]
The fuel cell 10 thus configured performs the electrochemical reaction shown in the following formulas (1) and (2), and directly converts chemical energy into electrical energy.
[0019]
Cathode reaction (oxygen electrode): 2H + + 2e-+ (1/2) O 2 → H 2 O (1)
Anode reaction (fuel electrode): H2 → 2H ++ 2e- (2)
[0020]
Turning to FIG. 1, a fuel cell control system 1 for a vehicle equipped with the fuel cell 10 having such a configuration will be described next. The vehicle fuel cell control system 1 is mounted on an automobile and produces a hydrogen-containing gas (fuel gas) from the fuel cell 10, methanol stored in the methanol tank 20, and water stored in the water tank 22. A reformer 24, a fuel gas supply passage 26 that connects the reformer 24 and the hydrogen-containing gas flow path 17b of the fuel cell 10 and sends the hydrogen-containing gas to the anode 13 pole side of the fuel cell 10, and a fuel An air supply that introduces air into the fuel gas that is connected to the gas discharge passage 28 for sending the gas discharged from the hydrogen-containing gas flow passage 17b of the battery 10 to the outside and the fuel gas supply passage 26 and flows through the fuel gas supply passage 26. And a passage 30. The vehicle fuel cell control system 1 further includes an electrical control system 40.
[0021]
An air pump 32 is provided in the air supply passage 30, and air is pumped into the fuel gas supply passage 26 by the air pump 32. The air pump 32 operates (on state) and stops (off state) in response to an external control signal. The gas discharge passage 28 is provided with an electromagnetic open / close valve (hereinafter referred to as an electromagnetic valve) 36, and the discharge of gas to the atmosphere side is controlled by the electromagnetic valve 36.
[0022]
The control system 40 includes an electronic control unit 42 composed of a microcomputer. The electronic control unit 42 includes an ignition switch 46 connected to an in-vehicle battery 44, and the air pump 32 and the electromagnetic valve 36 described above. Connected. The ignition switch 46 is a switch provided at the front of the driver's seat for controlling the driving / stopping of the vehicle. In this embodiment, the ignition switch 46 has three switching positions of OFF, ON, and START.
[0023]
The electronic control unit 42 is configured as a logic circuit centered on a microcomputer. Specifically, the CPU 42a executes predetermined calculations according to a preset control program, and controls necessary for executing various calculation processes by the CPU 42a. ROM 42b in which programs and control data are stored in advance, RAM 42c in which various data necessary for executing various arithmetic processes in the CPU 42a are temporarily read and written, and input processing circuit 42d for inputting electric signals from the ignition switch 46 And an output processing circuit 42e for controlling the air pump 32 and the electromagnetic valve 36 according to the calculation result in the CPU 42a.
[0024]
Air is introduced into the fuel gas supply passage 26 by controlling the air pump 32 and the electromagnetic valve 36 by the CPU 42a of the electronic control unit 42 having such a configuration. The air introduction control process will be described in detail next with reference to the flowchart of FIG. This air introduction control process is repeatedly executed every predetermined time.
[0025]
As shown in FIG. 3, when the processing is started, the CPU 42a first determines whether or not the ignition switch 46 is switched from the on state (ON switching position) to the off state (OFF switching position). (Step S100). Here, if it is determined that it is the switching time, the following processing is performed.
[0026]
First, the CPU 42a performs a process of starting a timer (not shown) built in the electronic control unit 42 (step S110). This timer is an automatic clock device that is provided inside the electronic control unit 42 and supplies a clock signal corresponding to the elapsed time.
[0027]
Subsequently, a process is performed to determine whether or not the elapsed time t measured by the timer has elapsed from the time when the ignition switch 46 is switched off has reached a predetermined time t0 (step S120). The predetermined time t0 is several tens of seconds. If it is determined that the elapsed time t has not reached the predetermined time t0, the air pump 32 is turned on (step S130), and the electromagnetic valve 36 is turned on (step S140). Then, it returns to step S120 and repeats step S120 thru | or step S140. Here, the process of steps S130 and S140 is configured to be repeatedly executed. However, when the air pump 32 is already on and the electromagnetic valve 36 is open, the processes of steps S130 and S140 are performed again. The configuration may be omitted.
[0028]
Thereafter, when it is determined in step S120 that the elapsed time t has reached the predetermined time t0, the CPU 42a switches the air pump 32 to the off state (step S150) and performs the process of switching the electromagnetic valve 36 to the closed state (step S150). Further, a process for resetting the timer started in step S110 is performed (step S170). Thereafter, the process returns to “RETURN” to end the process once.
[0029]
On the other hand, if it is determined in step S100 that the ignition switch 46 is not at the time of switching from the on state to the off state, the process returns to “return” and the process is temporarily terminated.
[0030]
According to the vehicle fuel cell control system 1 of the first embodiment configured as described above, the fuel gas supply passage 26 is provided for a predetermined period from when the ignition switch 46 is switched from the on state to the off state. Air is introduced into the. The fuel gas flowing through the fuel gas supply passage 26 is supplied from the reformer 24 to the anode 13 of the fuel cell 10, and when air is introduced into the fuel gas, the carbon monoxide adhering to the anode 13 is It is oxidized by air and converted into carbon dioxide, which is peeled off from the anode surface. Therefore, catalyst poisoning of the anode 13 is eliminated. In addition, the introduction timing of the air into the fuel gas may be when the vehicle is stopped so as not to adversely affect the driving state of the vehicle. In the fuel cell control system 1 of this vehicle, the vehicle is stopped. Since the timing is detected using the ignition switch 46 provided in the vehicle, the increase in the number of parts can be suppressed while preventing the catalyst poisoning.
[0031]
Next, a second embodiment of the present invention will be described. The second embodiment relates to a vehicle fuel cell control system having substantially the same configuration as that of the fuel cell 10 of the first embodiment, and differs from the first embodiment in the configuration of the oxygen-containing gas introducing means. Hereinafter, the fuel cell control system 201 for a vehicle according to the second embodiment will be described in detail focusing on this difference.
[0032]
FIG. 4 is a schematic configuration diagram of a fuel cell control system 201 for a vehicle as a second embodiment. As shown in FIG. 4, the vehicle fuel cell control system 201 includes the same fuel cell 10, reformer 24, fuel gas supply passage 26, gas discharge passage 28, battery 44 and ignition switch 46 as in the first embodiment. Provided (the same parts as in the first embodiment are given the same numbers). Furthermore, the vehicle fuel cell control system 201 includes an air supply passage 230 that is connected to the fuel gas supply passage 26 and introduces air into the fuel gas flowing through the fuel gas supply passage 26. Prepare.
[0033]
An accumulator 232 is provided in the air supply passage 230, and a heater 233 that is heated by waste heat of the reformer 24 is provided beside the accumulator 232. A second electromagnetic valve 234 and a third electromagnetic valve 235 are provided at both ends of the accumulator 232. The second electromagnetic valve 234 is provided on the upstream side of the accumulator 232 in the air supply passage 230, and the third electromagnetic valve 235 is provided on the downstream side thereof (the electromagnetic valve provided in the gas discharge passage 28). 36 is hereinafter referred to as a first electromagnetic valve 36).
[0034]
By controlling the opening and closing of the second and third electromagnetic valves 234 and 235, air is temporarily accumulated in the accumulator 232, the accumulated air is heated by the heater 233, and then the third electromagnetic valve 235 is opened. Then, air is introduced into the fuel gas supply passage 26. The process for accumulating air in the accumulator 232 (air accumulation control process) and the process for introducing air into the fuel gas supply passage 26 (air introduction control process) are controlled by the electronic control unit 242 of the control system 240. Executed. Both control processes will be described in detail next with reference to the flowcharts of FIGS.
[0035]
The air accumulation control process will be described first. This air accumulation control process is repeatedly executed every predetermined time. As shown in FIG. 5, when the processing is started, the CPU 242a first determines whether or not the ignition switch 46 is switched from the off state to the on state (step S300). Here, if it is determined that it is the switching time, the following processing is performed.
[0036]
The CPU 242a first switches the third electromagnetic valve 235 to the closed state, closes the downstream side of the accumulator 232 (step S310), and then starts a timer (not shown) built in the electronic control unit 242 (step S310). Step S320).
[0037]
Subsequently, a process is performed to determine whether or not the elapsed time t measured by the timer from the time when the ignition switch 46 is turned on has reached a predetermined time t1 (step S330). The predetermined time t1 is a time determined by the capacity of the accumulator 232, and is set to several tens of seconds here. If it is determined in step S330 that the elapsed time t has not reached the predetermined time t1, the second electromagnetic valve 234 is switched to the open state, and processing for opening the upstream side of the accumulator 232 is performed (step S340). Then, it returns to step S330 and repeats step S330 and step S340.
[0038]
On the other hand, when it is determined in step S330 that the elapsed time t has reached the predetermined time t1, the second electromagnetic valve 234 is switched to the closed state (step S350). As a result, air is accumulated in the accumulator 232 over a predetermined time t1. Next, a process for resetting the timer started in step S320 is performed (step S360). Thereafter, the process returns to “RETURN” to end the process once.
[0039]
On the other hand, if it is determined in step S300 that the ignition switch 46 is not at the time of switching from the off state to the on state, the process returns to “return” and the process is temporarily terminated.
[0040]
Next, the air introduction control process will be described. This air introduction control process is repeatedly executed every predetermined time. As shown in FIG. 6, when the process is started, the CPU 242a first determines whether or not the ignition switch 46 has been switched from the on state to the off state (step S400), and is at the time of switching. If determined, the following processing is performed.
[0041]
First, the CPU 242a controls the third electromagnetic valve 235 to be in an open state (step S410), and introduces the air accumulated in the accumulator 232 into the fuel gas supply passage 26. Next, a timer built in the electronic control unit 242 is started (step S420), and processing for determining whether or not the elapsed time t measured by the timer has reached a predetermined time t0 is performed (step S420). Step S430). The predetermined time t0 is the same as that in the first embodiment.
[0042]
If it is determined in step S430 that the elapsed time t has not reached the predetermined time t0, the first electromagnetic valve 36 is switched to the open state (step S440), and then the process returns to step S430, and steps S430 and S440 are performed. Repeatedly.
[0043]
Thereafter, when it is determined in step S430 that the elapsed time t has reached the predetermined time t0, the CPU 242a performs a process of switching the first electromagnetic valve 36 to the closed state (step S450), and further starts in step S420. Processing for resetting the timer is performed (step S460). Thereafter, the process returns to “RETURN” to end the process once.
[0044]
On the other hand, if it is determined in step S400 that the ignition switch 46 is not at the time of switching from the ON state to the OFF state, the process returns to “RETURN” and the process is temporarily terminated.
[0045]
According to the fuel cell control system 201 for a vehicle of the second embodiment configured as described above, when the ignition switch 46 is switched from the off state to the on state, air is supplied to the accumulator 232 for a predetermined time t1. Then, when the ignition switch 46 is switched from the on state to the off state, air is introduced into the fuel gas supplied to the fuel cell 10 for a predetermined time t0. As a result, the catalyst poisoning of the anode 13 can be eliminated as in the first embodiment. In addition, since the introduction timing of the air into the fuel gas is determined based on the stop time of the vehicle that has been detected using the ignition switch 46 that has been conventionally provided in the vehicle, as in the first embodiment, While preventing the catalyst poisoning, an increase in the number of parts can be suppressed.
[0046]
Furthermore, according to the vehicle fuel cell control system 201 of the second embodiment, the air is introduced into the fuel gas by releasing the air accumulated in the accumulator 232 without using power such as a pump. Therefore, energy saving can be achieved.
[0047]
By adjusting the capacity of the accumulator 232 in the second embodiment, the amount of air to be introduced into the fuel gas can be changed and the degree of prevention of catalyst poisoning can be managed.
[0049]
The embodiments of the present invention have been described above. However, the present invention is not limited to these embodiments, and it is needless to say that the present invention can be implemented in various modes without departing from the gist of the present invention.
[0050]
【The invention's effect】
As described above in detail, according to the fuel cell control device for a vehicle of the present invention, it is possible to realize in an in-vehicle system that an oxygen-containing gas is introduced into a fuel gas to eliminate electrode poisoning. In addition, since the vehicle stop timing suitable for the introduction of the oxygen-containing gas is determined using the operation switch provided in the vehicle, the excellent effect that the increase in the number of parts can be suppressed is achieved. Play.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a fuel cell control system 1 for a vehicle according to a first embodiment of the present invention.
FIG. 2 is a structural diagram showing a single cell of the fuel cell 10;
3 is a flowchart showing an air introduction control process executed by a CPU 42a of the electronic control unit 42. FIG.
FIG. 4 is a schematic configuration diagram of a vehicle fuel cell control system 201 as a second embodiment of the present invention.
FIG. 5 is a flowchart showing an air accumulation control process executed by a CPU 242a of the electronic control unit 242.
FIG. 6 is a flowchart showing an air introduction control process similarly executed by a CPU 242a.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Vehicle fuel cell control system 10 ... Fuel cell 11 ... Electrolyte membrane 12 ... Cathode 13 ... Anode 15 ... Current collector 17a ... Oxygen-containing gas channel 17b ... Hydrogen-containing gas channel 20 ... Methanol tank 22 ... Water tank 24 ... reformer 26 ... fuel gas supply passage 28 ... gas discharge passage 30 ... air supply passage 32 ... air pump 36 ... electromagnetic valve (first electromagnetic valve)
40 ... Control system 42 ... Electronic control unit 42a ... CPU
44 ... Battery 46 ... Ignition switch 201 ... Vehicle fuel cell control system 230 ... Air supply passage 232 ... Accumulator 233 ... Heater 234 ... Second electromagnetic valve 235 ... Third electromagnetic valve 240 ... Control system 242 ... Electronic control unit 242a ... CPU

Claims (3)

A vehicle,
A reformer mounted on the vehicle and generating fuel gas;
Mounted on the vehicle, a fuel cell control device for a vehicle with a supplied with the fuel gas to the electrode with a catalytic fuel cell generates an electromotive force,
Fuel gas supply means for supplying the fuel gas to the electrode of the fuel cell;
Oxygen-containing gas introducing means for introducing an oxygen-containing gas into the fuel gas;
A driving switch operated by the driver of the vehicle to control driving / stopping of the vehicle;
Fuel cell control device for a vehicle with a gas introducing actuation means for actuating the said oxygen-containing gas introducing means immediately when the operation switch is switched from the operation state to the stop state. The fuel cell control device for a vehicle according to claim 1,
  A fuel cell control device for a vehicle, further comprising a gas introduction stop unit that stops the operation of the oxygen-containing gas introduction unit after a predetermined time from when the operation switch is switched from the operation state to the stop state. The fuel cell control device for a vehicle according to claim 1,
The oxygen-containing gas introduction means includes
  A vehicle fuel cell control device comprising an accumulator for accumulating the oxygen-containing gas.

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