JP2004111212A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a direct-reforming fuel cell system most suitable for loading on a carriage with a large tilting movement such as a two-wheeled vehicle and a small boats. <P>SOLUTION: When a tilt sensor 15 inputs a detected signal of a tilting angle of larger than a prescribed angle for a period longer than a prescribed period, a control circuit 20 stops a fuel cell reaction, or an output of a fuel cell 1 is restrained, by which, a two-wheeled vehicle is not decided as toppled by the system loaded on it when parked in a tilting state with a side stand erected, nor when it is tilted in a large scale as at driving along a curve, but the system surely decides that the vehicle toppled when actually toppled, and stops the fuel cell reaction or restrains the output of the fuel cell. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell system.
[0002]
[Prior art]
In recent years, the problem of depletion of fossil fuels and the problem of environmental pollution have become serious, and the research and development of the use of fuel cells in place of fossil fuels for motors of automobiles and other vehicles has been eagerly studied and developed. Progressing.
[0003]
On the other hand, in power assisted bicycles, generally, a mechanism has been established in which an electric motor driven by a secondary battery is used for rotationally driving wheels. In the case of a power-assisted bicycle, home electric power is used for recharging the secondary battery, and a charger is connected to a household outlet for charging, and the bicycle itself is charged with fuel for charging the secondary battery. There are no power assisted bicycles with batteries.
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 64-017379 [Patent Document 2]
JP-A-64-071073
[Problems to be solved by the invention]
By the way, in the case of a power-assisted bicycle, since it is a two-wheeled vehicle, the vehicle body has a large inclination and often falls down. Therefore, when developing a fuel cell to be mounted on a power-assisted bicycle, it is safe even if the vehicle body leans or falls over, and even in such a state, the vehicle is continuously operated according to the charge amount of the secondary battery. There is a technical need to be able to operate and recharge.
[0006]
As a fuel cell mounted for charging a secondary battery of a power assisted bicycle, a direct reforming fuel cell using a solid polymer membrane as an electrolyte membrane is desirable from the viewpoint of small size, light weight and safety.
[0007]
FIG. 4 shows a configuration of a proposal example of a fuel cell system that generates power using such a direct reforming fuel cell. This fuel cell system includes a direct reforming type fuel cell 1 using a solid polymer membrane as an electrolyte membrane, an air pump 2 for supplying air to an air electrode 11 of the fuel cell 1, and a methanol / water storing an aqueous methanol solution as fuel. The tank 3 includes a methanol / water pump 4 for supplying an aqueous methanol solution of fuel from the methanol / water tank 3 to the fuel electrode 12 of the fuel cell 1. A methanol sensor 5 for monitoring the methanol concentration in the fuel is provided so as to be immersed in the liquid in the methanol / water tank 3. An exhaust pipe 6 is provided in the methanol / water tank 3 so as to discharge carbon dioxide gas generated by the fuel cell reaction. A gas-liquid separator 7 is connected to the air electrode 11 to receive unreacted air and reaction water discharged from the air electrode 11, separate the gas and liquid, and discharge the unreacted air from the exhaust pipe 8. In addition, the reaction product water is temporarily stored. Reference numeral 13 in the fuel cell 1 denotes a solid polymer electrolyte membrane.
[0008]
Such a direct reforming fuel cell system is effective as a small and lightweight fuel cell system for charging a secondary battery of a motorcycle, a motor-driven bicycle, a power assisted bicycle, and the like.
[0009]
FIG. 5 shows a configuration of a direct reforming fuel cell system mounted on a motorcycle. In FIG. 5, the elements denoted by the same reference numerals as those in FIG. 4 indicate the same elements. The polymer electrolyte fuel cell 1 is fixed in a state in which it is inclined by a certain angle in the front-rear direction in consideration of the circulation of liquid described later. Methanol as a fuel is supplied to the methanol / water tank 3 from a methanol tank 71 by a methanol pump 72. This fuel cell system includes a control circuit 20 for controlling a driving device. The control circuit 20 includes a drive circuit 21, an output control circuit 22, and a CPU 23, and executes control of the methanol concentration of the methanol / water fuel solution and output control of the generated power. Then, as information necessary for this control, a methanol concentration signal from the methanol sensor 5, a cell temperature signal, and a generated current / voltage signal from the temperature sensor 74 of the fuel cell 1 are input.
[0010]
When a direct reforming fuel cell system is used for charging a secondary battery of a power-assisted bicycle, if a Ni-Cd battery is used as the secondary battery, the fuel cell system is self-discharged to refresh the secondary battery. May be recharged. The control circuit 20 monitors the discharge state of the secondary battery, and when the secondary battery is completely discharged, the fuel cell system is started and recharged (self-discharge monitoring mode (i), low consumption mode (ii)). When the power-assisted bicycle actually travels, the mode shifts to the driving mode (iii), and the control circuit 20 controls the power generation of the fuel cell system according to the state of charge of the secondary battery.
[0011]
In such a direct reforming fuel cell 1, since methanol is used as a raw fuel and reaction water is also generated, it is necessary to take measures against leakage of these liquids, and carbon dioxide gas is generated by the fuel cell reaction. Since it circulates in a form mixed with methanol / aqueous solution, and similarly, unreacted air circulates in a form mixed with water produced by the reaction, gas-liquid separation is required for their removal. Therefore, in order to discharge unreacted air from the air electrode 11 of the fuel cell 1, carbon dioxide generated at the fuel electrode 12, and the like to the outside of the system, the methanol / water tank 3 and the gas-liquid separator 7 have exhaust pipes 6, 8 are provided.
[0012]
However, when the proposed fuel cell system is mounted as it is on a motorcycle or a small yacht, the fuel cell system has a structure in which a liquid leaks due to overturning or overturning. In addition, when it is overturned, there are problems such as the inability to separate gas and liquid and the circulation of the reaction solution.
[0013]
Further, in the proposed fuel cell system, the fuel cell 1 is attached to the motorcycle as shown in FIG. Is vertical and has a slight inclination in the front-back direction. However, as shown in FIG. 6, since the fuel cell 1 does not consider the inclination in the left-right direction, it is inevitable that the flow passage becomes clogged when the motorcycle falls down or is greatly inclined.
[0014]
In the case of a two-wheeled motor vehicle, it often occurs that the vehicle inclines or falls over greatly, and how to solve this problem has been a major challenge for putting a fuel cell system into practical use.
[0015]
As a technique relating to a fuel cell, a gas separator is described in JP-A-64-017379, and a gas-liquid separator is described in JP-A-64-071073. However, these publications do not describe measures against a large inclination or a fall.
[0016]
The present invention has been made in view of such technical problems, and as a direct reforming fuel cell system mounted on a vehicle having a large inclination such as a motorcycle or a ship, detects a fall using an inclination sensor, and detects a fall. It is an object of the present invention to provide a fuel cell system capable of stopping the system or controlling the output of the system.
[0017]
Another object of the present invention is to provide a fuel cell system capable of distinguishing between a tilted state in which a side stand is set up on a bicycle or a motorcycle and a falling state, and performing the above-described control only when the vehicle falls.
[0018]
[Means for Solving the Problems]
The fuel cell system according to the first aspect of the present invention includes a tilt sensor that detects a fall of the present system, and a control unit that stops a fuel cell reaction of the present system when the tilt sensor detects a fall of the present system. This is to prevent the system from malfunctioning by stopping and controlling the fuel cell reaction when the vehicle falls.
[0019]
A fuel cell system according to a second aspect of the present invention includes a tilt sensor that detects a fall of the present system, and a control unit that suppresses an output of the fuel cell of the present system when the tilt sensor detects a fall of the present system. The system suppresses the output of the fuel cell when it falls, preventing problems from occurring in the system, securing the minimum necessary power generation output, and supplementing the secondary battery connected to this system. Enables charging and prevents running out of batteries.
[0020]
According to a third aspect of the present invention, in the fuel cell system according to the first or second aspect, the fuel cell reaction is stopped when the tilt sensor continuously outputs a detection signal of a tilt angle equal to or greater than a predetermined angle for a predetermined time or more, or It is characterized by suppressing the output of the fuel cell, when such a system is mounted on a motorcycle, when the motorcycle is parked in an inclined state with the side stand upright, it is not determined that the vehicle has fallen, Further, even when the vehicle is temporarily inclined greatly, such as when traveling on a curve, it is not determined that the vehicle has fallen over. Instead, it is reliably determined that the vehicle has actually fallen over, and the fuel cell reaction is stopped or the output of the fuel cell is suppressed.
[0021]
According to a fourth aspect of the present invention, in the fuel cell system according to the first to third aspects, a methanol sensor for measuring a methanol concentration is attached to a predetermined location in a methanol / water tank, and when the system is inclined by a predetermined angle or more, the methanol sensor is used. The control unit receives the gas concentration detection signal from the liquid concentration detection signal of the methanol sensor and determines that the inclination is equal to or greater than a predetermined angle. The cost is reduced by not separately providing a special inclination sensor.
[0022]
According to a fifth aspect of the present invention, in the fuel cell system according to the first to fourth aspects, the control means performs a return control of the present system when the methanol sensor does not detect an inclination of a predetermined angle or more, and It is characterized in that various functions of the present system are checked before returning, and the occurrence of a malfunction due to a fall impact is checked before restarting.
[0023]
According to a sixth aspect of the present invention, in the fuel cell system according to the first to fifth aspects, the system is mounted on a motorcycle or a small ship, and the vehicle can be parked in a state of being inclined by a side stand or have a large inclination angle. The two-wheeled vehicle running on the vehicle is distinguished from the actual fall, and the fuel cell reaction is stopped at the time of the actual fall or the output of the fuel cell is suppressed to ensure the smooth running of the two-wheeled vehicle, etc. Prevents the occurrence of malfunctions when falling over or overturning, or prevents the occurrence of malfunctions, secures the minimum required power generation output, enables supplementary charging of secondary batteries connected to this system, and Be prevented.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a configuration of a direct reforming fuel cell system according to one embodiment of the present invention. The fuel cell system according to the present embodiment is a system to be incorporated in a motorcycle such as a power assisted bicycle, a motorcycle, and a motorbike.
[0025]
As shown in FIG. 1, a direct reforming fuel cell system according to the present embodiment includes a polymer electrolyte fuel cell 1, an air pump 2 for supplying air to an air electrode of the fuel cell 1, methanol as fuel. A methanol / water tank 3 for storing a mixed liquid of water, and a methanol / water pump 4 for supplying an aqueous methanol solution of fuel from the methanol / water tank 3 to the fuel electrode of the fuel cell 1 are provided. Methanol as a fuel is supplied to the methanol / water tank 3 from a methanol tank 71 by a methanol pump 72. Reference numeral 7 denotes a gas-liquid separator connected to the air electrode of the fuel cell 1.
[0026]
This fuel cell system includes a control circuit 20 for controlling a driving device. The control circuit 20 includes a drive circuit 21, an output control circuit 22, a CPU 23, and a storage device 24, and executes control of the methanol concentration of the methanol / water fuel solution and output control of the generated power. As the information necessary for this control, a methanol concentration signal from the methanol sensor 5, a cell temperature signal and a generated current / voltage signal from the fuel cell 1 are input, and the inclination sensor 15 for detecting the inclination angle of the motorcycle is input. A signal is input. Further, a display device 25 is connected to the control circuit 20 so that the CPU 23 displays necessary information.
[0027]
In the case where a Ni—Cd battery is used as a secondary battery, the direct reforming fuel cell system may be recharged after self-discharge for refreshing the secondary battery. The control circuit 20 monitors the discharge state of the secondary battery, and when the secondary battery is completely discharged, the fuel cell system is started and recharged (self-discharge monitoring mode (i), low consumption mode (ii)). When the motorcycle actually travels, the mode shifts to the operation mode (iii), and the control circuit 20 performs power generation control of the fuel cell system according to the state of charge of the secondary battery.
[0028]
Next, the operation of the fuel cell system having the above configuration will be described. The fuel cell power generation operation is the same as that of the conventionally proposed fuel cell system shown in FIGS. The feature of the operation of the fuel cell system according to the present embodiment is that the control circuit 20 controls the fuel cell power generation based on the signal of the tilt sensor 15.
[0029]
The tilt sensor 15 outputs a signal when the two-wheeled vehicle is tilted more than a predetermined angle. The tilt sensor 15 may detect a tilt angle and output a tilt angle signal. The control circuit 20 determines based on the signal from the tilt sensor 15 whether or not the system is within the posture range where normal power generation is possible.
[0030]
In the case of a motorcycle, a side stand is set up for parking, in which case the inclination angle becomes a certain angle. Therefore, the control circuit 20 determines that (1) the signal from the tilt sensor 15 is a tilt angle larger than the tilt angle when the stand is set up, and (2) the detection signal of the large tilt angle continues for several seconds. In this case, it is determined that the vehicle has fallen, and the fuel cell control is performed.
[0031]
During actual running of the motorcycle, depending on the speed, it may be possible to run at an angle of inclination larger than the angle of inclination when parking with the side stand up, but in such a case, it will be almost upright within a few seconds. Since it returns to the posture, when a large inclination angle is detected, it is determined that the vehicle has fallen if it continues for several seconds.
[0032]
<Control at the time of falling> The fuel cell control when it is determined that the vehicle has fallen is as follows.
[0033]
(I) If the motorcycle falls, it is highly likely that fuel cell power generation cannot be performed normally due to air entrapment or the like, so the system is stopped.
[0034]
(Ii) The event of the occurrence of a fall is recorded as a history in the storage device 24, and the mode shifts to the check mode at the next start-up. Also used as maintenance data.
[0035]
In the check mode, the value of the inclination sensor 15, the concentration value of the methanol sensor 5, the amount of methanol / water solution, the amount of methanol / water pump drive current (air entrapment check), the amount of water generated at the air electrode, the amount of methanol in the methanol tank 71, etc. Confirm. If these are within the normal range, the restart is permitted.
[0036]
During the check, the display device 25 displays to the user that the check is being performed.
[0037]
(Iii) At the time of restarting after the system is stopped, if the signal of the inclination sensor 15 returns to normal and a certain period of time has passed since the return, it is determined that the liquid in the piping has settled and fuel cell power generation is started. restart.
[0038]
As a result, even if the direct reforming fuel cell system is mounted on a vehicle that often has a large inclination posture such as a motorcycle and may fall over, it is possible to distinguish between a large transient inclination and an actual fall. In addition, when the vehicle falls, the power generation of the fuel cell is stopped to prevent the occurrence of a trouble, and when the vehicle returns to a normal posture later, the power generation of the fuel cell can be smoothly restarted.
[0039]
In addition, instead of stopping the operation of the fuel cell at the time of judging the fall, the minimum required power generation output is also secured, the secondary battery connected to the present system can be supplementarily charged, and the running out of the battery can be prevented. Output may be limited.
[0040]
Next, a direct reforming fuel cell system according to a second embodiment of the present invention will be described with reference to FIG. In the first embodiment, the tilt sensor 15 for detecting the tilt angle of the fuel cell system is employed. The tilt sensor 15 detects that the tilt angle becomes larger than the tilt angle when the side stand is set up. If it is possible, the inclination angle itself may not be detected exactly.
[0041]
Therefore, in the second embodiment, instead of the tilt sensor 15 used in the fuel cell system of the first embodiment, as shown in FIG. At the same time as the density detection, it is used as a tilt sensor. The configuration of the fuel cell system according to the second embodiment is the same as that of the first embodiment shown in FIG. 1 except that the tilt sensor 15 is omitted.
[0042]
As the methanol sensor 5 for measuring the methanol concentration, a viscosity sensor using a quartz oscillation element is used, but in the quartz oscillation element type sensor, a measurement signal in a liquid and a measurement signal in a gas are greatly different.
[0043]
Therefore, in the present embodiment, the methanol sensor 5 is immersed in a methanol / water solution if the vehicle is a vehicle such as a motorcycle as shown in FIG. 2 and the fuel cell system is in a normal posture. When it is tilted to an angle that can be considered, it is installed in a place where it comes out of the liquid to the gas side, and its concentration measurement signal is monitored by the control circuit 20 side. However, as in the first embodiment, if the inclined state continues for several seconds, it is determined that the vehicle has fallen.
[0044]
As a result, in the second embodiment, the cost of newly adding a tilt sensor can be reduced, and the system can be reduced in cost as compared with the first embodiment.
[0045]
In addition, as the methanol sensor 5 for detecting the methanol concentration, an ultrasonic sensor as shown in FIG. Even with this ultrasonic methanol sensor 5, the propagation speed of the ultrasonic wave is largely different between the liquid and the gas, so that the control circuit 20 can determine that it has fallen when it receives an abnormal concentration signal. . In addition, even when an electric resistance measurement type or light refractive index type concentration sensor is employed as the methanol sensor 5, the fall determination can be performed in the same manner.
[0046]
【The invention's effect】
As described above, according to the present invention, it is possible to minimize the influence on the system when the direct reforming type fuel cell falls down, and in particular, a vehicle having a sharp inclination swing, for example, a small ship such as a motorcycle, a boat, or a yacht. A fuel cell system suitable for mounting on a vehicle can be provided.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a system configuration according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram showing an operation of a methanol sensor that also serves as a tilt sensor in the system according to the second embodiment of the present invention.
FIG. 3 is an explanatory diagram showing the operation of another example of a methanol sensor employed in the second embodiment.
FIG. 4 is a block diagram of a proposed direct reforming fuel cell system.
FIG. 5 is a block diagram showing an example of arrangement when the proposed direct reforming fuel cell system is mounted on a motorcycle.
FIG. 6 is an explanatory view showing that when the proposed direct reforming fuel cell system is mounted on a motorcycle, the fuel cell swings right and left with the inclination of the vehicle body.
[Explanation of symbols]
Reference Signs List 1 fuel cell 2 air pump 3 methanol / aqueous solution tank 4 methanol / water pump 5 methanol sensor 6 exhaust pipe 7 gas-liquid separator 8 exhaust pipe 11 air electrode 12 fuel electrode 13 solid polymer electrolyte membrane 15 tilt sensor 20 control circuit 21 drive circuit 22 output control circuit 23 CPU
24 storage device 25 display device 71 methanol tank 72 methanol pump

Claims (6)

An inclination sensor for detecting an inclination of the system,
A fuel cell system comprising: control means for stopping the fuel cell reaction of the present system when the tilt sensor detects a tilt greater than a predetermined angle of the present system. An inclination sensor for detecting an inclination of the system,
A fuel cell system comprising: control means for suppressing the output of the fuel cell of the present system when the tilt sensor detects a tilt greater than a predetermined angle of the present system. The control means stops a fuel cell reaction or suppresses an output of the fuel cell when the tilt sensor continuously outputs a detection signal of a tilt angle equal to or more than a predetermined angle for a predetermined time or more. The fuel cell system according to claim 1. A methanol sensor for measuring the methanol concentration is attached to a predetermined location in the methanol / water tank, and when the system is tilted at a predetermined angle or more, the liquid comes out of the liquid to output a gas concentration detection signal,
The method according to claim 1, wherein the control unit receives a gas concentration detection signal from the liquid concentration detection signal of the methanol sensor, and determines that the inclination is equal to or greater than a predetermined angle. Fuel cell system. The control means performs a return control of the present system when the methanol sensor does not detect an inclination of a predetermined angle or more, and checks various functions of the present system prior to the return. The fuel cell system according to any one of claims 1 to 4, wherein: The fuel cell system according to any one of claims 1 to 5, wherein the system is mounted on a motorcycle or a small ship.

Images