JP2006040836A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to perform detection of the remaining quantity of the fuel for power generation and alcohol concentration accurately and at low cost in a fuel cell system mounted on a portable equipment. <P>SOLUTION: The fuel cell system comprises a fuel cell, a fuel cartridge 3, and a mechanism for attaching and detaching the fuel cartridge 3. In the periphery of the fuel cell system, an installation space for mounting the fuel cartridge, a plurality of electrodes 5, 6, 7 arranged separated with prescribed spacings along the side face of the installation space, a detection circuit 8 for detecting the electrostatic capacity between these electrodes, and an interface circuit which sends out as data by operating the signals outputted from the detection circuit 8 are provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system, and more particularly to a fuel cell system using a suitable fuel remaining amount detection method and fuel type determination method in a portable fuel cell system including a fuel cartridge.

  In recent years, various new power supply systems and power generation systems (hereinafter referred to as fuel cells) including a fuel cell capable of realizing an extremely high energy use efficiency of, for example, about 30 to 40% with little environmental impact (burden). , Generically referred to as “power supply system”), for the purpose of application to a drive power supply for vehicles, a power supply system for business use, a cogeneration system for home use, etc., or an alternative to the above-described chemical battery As a purpose, research and development for practical use are actively conducted. However, in the future, in order to reduce the size and weight of a power system with high energy use efficiency such as a fuel cell and apply it as a portable or portable portable power source, for example, an alternative (compatible product) of the above-described chemical battery, Have the following problems.

  That is, for example, in a power supply system having the above-described fuel cell (hereinafter referred to as a fuel cell system), power is generated (power generation) using power generation fuel (power generation fuel). Keeping track of the remaining amount of fuel, when the remaining amount of fuel is low, quickly replace the fuel cartridge currently in use with a new fuel cartridge filled with fuel, etc. Need to recover (increase).

For this reason, the fuel cell system needs to be provided with a remaining amount detecting means for detecting the remaining amount of fuel in order to always grasp the current remaining amount of fuel. Various methods have been proposed as remaining amount detection means for detecting the remaining amount of fuel in general, but most of them are suitable for a fuel cell system for portable devices and are configured to be small and inexpensive. Was not easy. (For example, see Patent Document 1)
Among them, a method for detecting an electrical resistance by providing an electrode on the inner surface of a fuel cartridge has been proposed for a fuel cell system for portable equipment. (See Patent Document 2)
Japanese Patent Application Laid-Open No. 62-191722 JP 2004-93409 A

    However, in the above conventional technique, since the detection means is on the fuel cartridge side, each of the replacement fuel cartridges also requires detection means, and when an expensive part is used to increase the remaining amount detection accuracy of the system Since the cost increases, it is difficult to achieve both detection accuracy and low cost.

  In addition, there is a risk of using the wrong fuel because the concentration of methanol used varies depending on the fuel cell manufacturer.

  Accordingly, an object of the present invention is to make it possible to detect the remaining amount of fuel for power generation and the alcohol concentration with high accuracy and at low cost, particularly in a fuel cell system mounted on a portable device.

  In order to solve the above problems, a fuel cell system according to claim 1 of the present invention includes a fuel cell using an alcohol aqueous solution as a fuel, a fuel cartridge storing the fuel, a mechanism for attaching and detaching the fuel cartridge, A fuel cell system including a peripheral portion having a mechanism for supplying the fuel from the fuel cartridge to the fuel cell, wherein the peripheral portion includes a mounting space for mounting the fuel cartridge, and the mounting space. A plurality of electrodes spaced apart at predetermined intervals along the side surface, a detection circuit for detecting a capacitance between the plurality of electrodes, and a signal output from the detection circuit It has an interface circuit for sending out as data.

  According to this configuration, the electrostatic capacity between the conductors provided in the mounting space of the fuel cartridge changes according to the remaining amount of fuel in the fuel cartridge. it can. In this configuration, since the electrode serving as the detection means is on the fuel cell system side, it is not necessary to attach a special mechanism to the fuel cartridge. Further, since the electrode does not touch the corrosive alcohol aqueous solution, it is excellent in durability.

  The fuel cell system according to claim 2 of the present invention is the fuel cell system according to claim 1, wherein three or more of the electrodes are provided, and two of these are static according to the remaining amount of the fuel. It arrange | positions so that an electric capacity may change, and the remaining electrodes are arrange | positioned as a comparative electrode in the position which does not affect the residual amount of fuel. With this configuration, the remaining amount can be detected more accurately.

  A fuel cell system according to a third aspect of the present invention is the fuel cell system according to the first aspect, wherein a part of the fuel cartridge always holds a constant fuel regardless of a remaining amount of fuel. And a mechanism for determining the alcohol concentration of the fuel based on the detected capacitance value, and having an electrode provided so as to detect the capacitance of this portion. When a cartridge with a different mixing ratio of water and water is mounted, it can be detected and an abnormality can be determined.

  Finally, a fuel cell system according to a fourth aspect of the present invention is the fuel cell system according to the first aspect, wherein the fuel cell system is located in a part of the fuel supply mechanism and detects a capacitance of the part. And a mechanism for determining the alcohol concentration of the fuel and the presence / absence of the fuel based on the detected capacitance value, wherein the function described in claim 3 is provided. In addition, the fuel supply pump is activated after the fuel cartridge is connected, and it is detected that the fuel has been sent to the device, and that the fuel has been exhausted. be able to.

  According to the present invention, it is possible to easily and inexpensively calculate the remaining amount of fuel for power generation in the fuel cartridge of the fuel cartridge by measuring the capacitance value between the two conductors constituting the electrode. Can do.

  In addition, by providing three or more electrodes, more accurate detection is possible.

  Furthermore, since the type of fuel can be determined, it is possible to take measures when an incorrect fuel cartridge is connected.

  Since it can detect the presence or absence of fuel, it detects that the cartridge is empty and issues an alarm, prompts the user to install a new cartridge, and activates the pump when a new cartridge is connected or started. It is possible to detect that the fuel has reached a position where fuel can be supplied.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a fuel cell system to which the present invention is applied will be described in detail with reference to the drawings.
<First Embodiment>
FIG. 1 shows a fuel cell system 2 according to a first embodiment, a portable device (a notebook computer 1 in the figure) and a fuel cartridge 3 on which the fuel cell system 2 is mounted.

  The fuel cell system 2 according to the present embodiment has a battery pack mounting portion (not shown) at the rear of the notebook personal computer, and is attached here. The fuel cartridge 3 is mounted in the fuel cell system 2 so that all or part of the fuel cartridge 3 is stored in the mounting space 4 of the fuel cartridge 3.

  The configuration of the present invention is provided in the mounting space 4 of the fuel cartridge 3 and its details are shown in FIG.

  The fuel cartridge 3 is inserted between the electrodes 5, 6 and 5 and 6, and the capacitance C between the electrodes 5 and 6 is the electrode area D, the distance L between the electrodes, and the substance placed between the electrodes. It is determined by the relative dielectric constant E and is given by Equation 1.

C = ED / L (1)
In the configuration of the present invention, since D and L are fixed, C is determined only by E.

  The relative permittivity of air is 1, methanol is 33, and water is 88.

  If the ratio of water and methanol inside the fuel cartridge is known, the remaining amount of fuel can be obtained by obtaining the C value. When the remaining amount is zero, C is the smallest, and C when the fuel is full indicates the largest value.

  The electrode 7 is a comparative electrode for obtaining the capacitance C between the electrodes 5 and 6, and air is interposed between the electrodes 6 and 7 in the present embodiment. By obtaining the capacity between the electrodes 5 and 6 by the ratio of the capacity between the electrodes 6 and 7, the remaining amount of fuel can be measured with the highest accuracy.

  The capacitance between the electrodes 6 and 7 can be replaced with a capacitor of an electrical component. In this case, the electrode 7 is not necessary.

  Reference numeral 8 denotes a capacitance detection circuit. The configuration of this circuit will be described later.

  Reference numeral 23 denotes an interface circuit that calculates data detected by the capacitance detection circuit 8 to generate a fuel-related signal and transmits it to the notebook computer 1.

  The notebook personal computer 1 can display fuel information on the screen or information for instructing replacement of the fuel cartridge.

The mechanism for detecting the remaining amount of fuel will be described in detail with reference to FIG.
Electrodes 5 and 6 are arranged on both sides of the fuel cartridge 3 so that the fuel enters up to the shaded portion.
Since the portion 21 of the electrode 5 corresponds to a portion containing fuel, the capacity depends on the relative dielectric constant of the fuel.

  Since the portion 22 corresponds to a portion not containing fuel, that is, an air portion, the capacity depends on the dielectric constant of air and is extremely small. If the liquid level is perpendicular to the electrodes 5 and 6, the total capacity between the electrodes 5 and 6 is the sum of the capacity of the portion 21 and the capacity of the portion 22.

FIG. 4 is a diagram for explaining the influence of the inclination of the fuel cartridge 3.
The electrode 5 is provided in front of the fuel cartridge 3, and a similar electrode 6 is provided on the back side of the fuel cartridge 3.

  FIG. 4 shows a state in which the fuel is about 2/5 of the internal volume of the cartridge.

  (A), (b), and (c) of FIG. 4 show cases where the angle at which the fuel cell equipped with the cartridge is used is different, and if the electrode 5 (and electrode 6) has an appropriate shape, The liquid level is always perpendicular to the electrodes 5 and 6, and the detection error due to the tilt can be reduced.

FIG. 5 is a block diagram illustrating an example of the capacitance detection circuit 8.
Reference numeral 14 denotes an oscillator, and reference numerals 15 and 16 denote inverting mittens, which amplify the output of the oscillator 14 and apply it to both ends of the electrodes 5 and 7.

  The phases of the outputs of 15 and 16 are shifted by 180 degrees.

If the capacitance between the electrodes 5 and 6 is equal to the capacitance between the electrodes 6 and 7, the electrode 6 becomes the middle point and no electrical signal is output, but if there is a difference in capacitance, the AC voltage is proportional to the magnitude of the difference. Will occur.
The absolute value of the difference appears as the magnitude of the amplitude, and the sign of which capacity is larger can be observed as the phase.

Therefore, after amplification by the amplifier 17, phase detection by the synchronous detection circuit 18 makes it possible to obtain a capacitance ratio value including polarity as a DC voltage.
The output of the synchronous detection circuit 18 is smoothed by a resistor / capacitor filter, amplified by a voltage amplification circuit 19 and output.
<Second Embodiment>
FIG. 6 shows a configuration for performing fuel type determination in the fuel cell system of the present invention. In FIG. 6, a portion 9 of the fuel cartridge 3 has a structure in which a constant amount of fuel is always interposed regardless of the remaining amount of fuel. The electrodes 10 and 11 are arranged so as to sandwich the nine portions, and by measuring the capacity between the ten and eleven portions, the concentration of the fuel (mixing ratio of methanol and water) can be measured.

The capacity is the smallest in the case of 100% methanol, and the capacity is the largest in the case of 100% water.
<Third Embodiment>
FIG. 7 shows another configuration for determining the type of fuel in the fuel cell system of the present invention. The fuel sent from the fuel tank 3 by the fuel pump 12 is sent to the fuel cell 13.
Electrodes 10 and 11 are provided in the middle of the fuel pipe, and the type of fuel and the presence or absence of fuel can be detected by the capacitance between them.
<Fourth embodiment>
In FIG. 8, fuel is contained in a bag-shaped aluminum pack, which is stored in an outer case.
When the fuel is full, the distance between the aluminum pack 20 and the electrodes 5 and 6 is small, so the capacitance is large. As the fuel is reduced, the aluminum pack is deflated. Get smaller.

  The fuel cell system of the present invention is useful as a power supply system for portable devices such as notebook computers.

The figure which shows the application form of the fuel cell system which concerns on 1st Embodiment. 1 is a schematic diagram of a configuration of a fuel cell system according to a first embodiment. Illustration of the remaining fuel detection principle Illustration of the effect of cartridge tilt Circuit block diagram of the capacitance detection circuit 8 Configuration schematic diagram of fuel cell system according to second embodiment Configuration schematic diagram of fuel cell system according to third embodiment Configuration schematic diagram of fuel cell system according to fourth embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Notebook personal computer 2 Fuel cell system 3 Fuel cartridge 4 Mounting space 5, 6, 7, 10, 11 Electrode 8 Capacitance detection circuit 14 Oscillation circuit 15, 16 Inversion amplification circuit 17 Amplification circuit 18 Synchronous detection circuit 19 Voltage amplification circuit 20 Fuel cartridge 23 Communication interface

Claims (4)

Peripheral portion comprising a fuel cell using an alcohol aqueous solution as a fuel, a fuel cartridge storing the fuel, a mechanism for detaching the fuel cartridge, and a fuel supply mechanism for supplying the fuel from the fuel cartridge to the fuel cell A fuel cell system comprising:
In the peripheral portion, a mounting space for mounting the fuel cartridge, a plurality of electrodes arranged at predetermined intervals along a side surface of the mounting space, and a capacitance between the plurality of electrodes A fuel cell system comprising: a detection circuit for detecting a signal; and an interface circuit for calculating a signal output from the detection circuit and sending it as data. Three or more electrodes are provided, two of which are arranged so that the capacitance changes according to the remaining amount of fuel, and the remaining electrodes are used as comparative electrodes at positions that do not affect the remaining amount of fuel. The fuel cell system according to claim 1, which is arranged. A part of the fuel cartridge has a mechanism that always holds a constant fuel regardless of the remaining amount of fuel, and has an electrode provided to detect the capacitance of this portion, The fuel cell system according to claim 1, further comprising a mechanism for determining an alcohol concentration of the fuel based on a capacitance value. The fuel supply mechanism has an electrode provided in a part of the fuel supply mechanism so as to detect a capacitance of the part, and the alcohol concentration of the fuel and the presence or absence of the fuel are determined by the detected capacitance value. The fuel cell system according to claim 1, further comprising a mechanism for determining