JP2006252812A - Fuel cell and electrical apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily detect the remaining amount of fuel of a fuel cell capable of loading in a portable terminal apparatus with a voltage signal same as a secondary battery. <P>SOLUTION: A slide type variable resistor (comprising a slider 117 and a carbon film resistor 119) is installed in the fuel cell 100, and the slider 117 is connected to a movable partition 116 of a fuel tank 110. Constant voltage generated with the fuel cell 100 is applied to both ends of the carbon film resistor 119. Voltage obtained by partially dividing the constant voltage is taken out through the slider 117 and a remaining amount detecting terminal. Since the position of the slider 116 moves according to increase in by-products, the remaining amount of fuel of the fuel cell 100 can be detected with the voltage signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell and an electric device, and more particularly to a detection function for electrically detecting the remaining amount of fuel.

  Conventionally, various chemical batteries are used in every field for consumer use and industrial use. For example, primary batteries such as alkaline batteries and manganese batteries are widely used in watches, cameras, toys, portable acoustic devices, and the like.

  On the other hand, secondary batteries such as nickel / cadmium storage batteries, nickel / hydrogen storage batteries, and lithium ion batteries are used in portable devices such as portable telephones, personal digital assistants (PDAs), digital video cameras, and digital still cameras, which have recently become widespread. ing.

  In recent years, as the interest in environmental issues and energy issues has increased, there is a fuel cell that has less environmental impact (burden) and can realize extremely high energy utilization efficiency of, for example, about 30 to 40%. It attracts attention and is expected as a power source to replace the above-described chemical battery.

  Fuel cells convert the combustion energy of materials directly into electrical energy, and are several times more energy efficient than conventional secondary batteries, thus extending battery life in mobile devices such as mobile phone terminals. There is a feature that is possible. In addition, if the by-products generated during power generation are low pollution with, for example, water and carbon dioxide, and continuous supply of fuel and oxygen is possible, continuous power generation is possible.

  Conventionally, in a fuel cell, an oxygen supply mechanism that forcibly circulates and supplies oxygen to the positive electrode and a fuel supply mechanism that supplies fuel to the negative electrode are indispensable. By using the technique as described in No. 1, it is possible to manufacture a small-sized fuel cell from which these mechanisms are removed, and the utility value as a power source for electric equipment is increasing.

  Fuel cells are classified into phosphoric acid type, solid polymer type, molten carbonate type, solid oxide type, and the like based on the type of electrolyte layer. As a power source for portable electronic devices, a polymer electrolyte fuel cell is suitable because it can operate at a low temperature around room temperature and has a solid electrolyte that is resistant to vibration and easy to mass-produce. .

  In the polymer electrolyte fuel cell, as a fuel supply method, a method of contacting hydrogen gas with the fuel electrode, a method of reforming organic fuel to generate hydrogen gas, and then contacting the hydrogen gas with the fuel electrode, and There is known a method of directly supplying a liquid fuel capable of supplying protons by reaction to a fuel electrode.

  The method using hydrogen gas is not suitable for a small power source for portable electronic devices because it is difficult to handle hydrogen gas or an apparatus for reforming organic fuel is required. Therefore, it can be said that a fuel cell using liquid fuel is suitable from the viewpoint of constituting a small power source for portable electronic equipment.

  In particular, a methanol direct fuel cell (direct methanol fuel cell) that directly supplies an aqueous methanol solution as a liquid fuel to the fuel electrode is easy to handle, and the by-product is water (and some water). In recent years, carbon dioxide has attracted attention because it is harmless to the human body.

In the methanol direct fuel cell, at the fuel electrode supplied with the aqueous methanol solution, as shown in the following formula (1), methanol and water react to produce carbon dioxide (CO ₂ ), proton (H ⁺ ), and Electrons (e ⁻ ) are generated.

Protons generated at the fuel electrode pass through the polymer electrolyte layer toward the air electrode, and electrons flow to an external circuit connected to the fuel electrode. Electrons that have finished their work in the external circuit go to the air electrode. Carbon dioxide is discharged outside the system.
CH ₃ COOH + H ₂ O → 3CO ₂ + 6H ⁺ + 6e ⁻ (Formula 1)

In the air electrode, as shown in the following formula (2), oxygen (O ₂ ) obtained from air, protons (H ⁺ ) coming from the fuel electrode, and electrons coming from the fuel electrode through an external circuit Reaction with (e ⁻ ) produces water (H ₂ O).
O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O (Formula 2)

  In a methanol direct fuel cell, a relatively large fuel cell may be provided with a device for detecting the level of the fuel contained in the fuel tank and a device for detecting the weight of the fuel. is there.

  With these devices, it is possible to predict the remaining amount of fuel stored in the fuel tank to be supplied to the fuel electrode of the fuel cell, and thus it is possible to detect the necessity of fuel replenishment. In a relatively large fuel cell, the fuel tank is usually provided with a fixed orientation. Therefore, by providing a device for detecting the fuel level and fuel weight in the fuel tank as described above, the remaining amount of fuel can be obtained. In addition, it is possible to easily detect the amount of decrease.

  For example, Patent Document 2 discloses a fuel cell system including a device that predicts the remaining amount of fuel by detecting the fuel level.

JP 2000-268835 A

JP-A-5-258760

  Since the output voltage of a secondary battery such as a nickel metal hydride battery decreases with time, the remaining battery level can be obtained by detecting the level of the output voltage. However, in the fuel cell, the output voltage is almost constant regardless of the remaining amount of fuel, and the method of detecting the remaining amount of fuel by monitoring the output voltage cannot be adopted.

  In addition, when a small fuel cell is mounted on a portable device such as a mobile phone terminal, the portable device changes its posture in various ways (that is, there is no guarantee that a certain posture is maintained). The method of detecting the liquid level of the fuel as described in Patent Document 2 cannot be adopted.

  The present invention has been made based on such considerations, and enables the remaining amount of a fuel cell that can be mounted on a portable terminal device to be easily detected by a voltage signal in the same manner as a secondary battery. With the goal.

The fuel cell of the present invention moves while contacting the main surface of the resistor as the resistance connected between the output voltage terminals of the fuel cell and the by-products generated by the power generation of the fuel cell increase. A variable resistor provided with a movable electrode terminal, and a fuel for outputting, to the outside, a voltage taken out of the variable resistor via the movable electrode terminal as a fuel remaining amount detection signal in the fuel section And a remaining amount detection terminal.
The fuel cell of the present invention further contacts the main surface of the resistor as the resistance connected between the output voltage terminals of the fuel cell and by-products generated by the power generation of the fuel cell increase. A slide-type variable resistor having a sliding contact that moves while moving, and the voltage of the slide-type variable resistor, which is taken out through the slider, is used as the remaining fuel in the fuel section. A fuel remaining amount detection terminal for outputting to the outside as a quantity detection signal;

  The output voltage of the fuel cell is almost constant regardless of the fuel consumption (elapsed time). For this reason, the remaining amount of fuel cannot be detected by directly monitoring the output voltage. On the contrary, the constant voltage characteristic of the voltage is actively used. That is, the output voltage of the fuel cell is applied as a power supply voltage (constant voltage) across the resistance of the slide type variable resistor. The resistance is divided into two at the position of the terminal electrode such as the sliding contact of the slider (that is, the constant voltage is divided by two resistors), and the resistance is divided. The voltage is taken out via the slider. Since the output voltage of the fuel cell can be regarded as constant with respect to time as described above, the voltage taken out via the slider changes depending only on the position of the slider. And in this invention, the position of a slider is made to move with the increase (volume) of the by-product produced | generated by the electric power generation of a fuel cell. An increase in by-products means that the remaining amount of fuel has decreased due to power generation by the fuel cell. As the by-product (volume) increases, the position of the slider of the slide-type variable resistor changes, and as the displacement changes, the value of the voltage extracted via the slider also changes. As a result, the remaining amount of fuel can be observed (detected) as a voltage value. Further, the structure of the remaining amount detection mechanism is simple and can be applied to a small fuel cell.

  In one aspect of the fuel cell of the present invention, a movable partition wall is provided in the fuel tank to separate the fuel portion and the byproduct storage portion, and the movable partition wall is stored in the byproduct storage portion. As the amount of the by-product increases, it moves in a predetermined direction, and one end of the slider opposite to the sliding contact is connected to the movable partition.

  The inside of the fuel tank is divided into two parts by a movable partition, and one space is used as a fuel part, and the other space is used as a by-product containing part. One end of the slider is connected (directly or indirectly) to the movable partition. As power generation by the fuel cell proceeds, the volume of the by-product in the by-product storage unit increases, and the movable partition is pressed accordingly. The moving contact of the movable partition moves the sliding contact of the slider, and the voltage (voltage divided by resistance) taken out via the slider changes. In order to smoothly move the movable partition wall, the inside of the by-product storage unit is filled with an absorbent material (such as a superabsorbent polymer) that absorbs the by-product and increases its volume. Is desirable. Further, it is desirable to provide a guide for regulating the moving direction of the slider in the variable resistor so that the movable partition wall moves in a predetermined direction. In addition, when the movable partition moves due to the pressure from the by-product storage unit, the volume of the fuel unit is reduced, and the fuel is efficiently pushed out to the power generation unit, so that the fuel can be used up sufficiently. An effect is also obtained.

  In the fuel cell of the present invention, the voltage signal indicating the remaining amount of fuel output from the remaining fuel amount detection terminal includes a signal having characteristics similar to the characteristics of the output voltage with respect to time of the secondary battery.

  Accordingly, the remaining amount detection technology (provided remaining amount detection technology) by detecting the output voltage of the secondary battery can be applied to the remaining amount detection technology of the fuel cell. Also, both the secondary battery and the fuel cell are mounted on the electrical equipment, the secondary battery is used as a direct power source, and the fuel cell is used as a backup for the secondary battery (that is, the remaining capacity of the secondary battery). May be used for the purpose of charging the secondary battery by power generation by the fuel cell. If the technology of this aspect is used, the remaining amount of the secondary battery and the remaining amount of the fuel cell can be detected by a common remaining amount detector, the configuration of the remaining amount detector can be simplified, and it contributes to the miniaturization of the electric device. .

  In another aspect of the fuel cell of the present invention, the fuel cell is a methanol direct fuel cell that generates power by a chemical reaction between an aqueous methanol solution and oxygen to produce water as the byproduct.

  A methanol direct fuel cell that supplies an aqueous methanol solution as a liquid fuel directly to the fuel electrode is easy to handle, and the by-product is water (and some carbon dioxide), which is harmless to the human body. In addition, since the fuel cell itself can be reduced in size, it can be mounted on a portable device such as a mobile phone. Therefore, by applying the fuel remaining amount detection technology of the present invention to a methanol direct fuel cell, it is possible to realize an easy-to-use power supply system that can be mounted on small and light equipment.

  Further, an electrical device of the present invention includes a fuel remaining amount detection unit that receives the remaining amount detection signal output from the fuel remaining amount detection terminal of the fuel cell of the present invention and detects the remaining amount of fuel, And a notification unit that notifies the user of fuel remaining amount information based on the detection result.

  In the electric equipment, the remaining fuel amount is automatically detected using the voltage indicating the remaining amount of fuel output from the fuel cell of the present invention. The notification is made without delay. Thereby, the user can know that the amount of fuel has become small, and can perform fuel filling and fuel cell replacement at an appropriate timing.

  The electric device of the present invention is a mobile terminal device.

  According to the present invention, in a mobile terminal such as a mobile phone terminal, the degree of battery consumption can be shown to the user at an appropriate timing, and user convenience is improved.

  In the present invention, the fact that the output voltage of the fuel cell exhibits a constant voltage characteristic is actively used, and a variable resistor that is a proven electric element is used, and the voltage obtained by dividing the constant voltage by the resistance is used as a movable electrode. It is configured to take out via the terminal, and the movable electrode terminal is displaced as the by-product increases, so that the remaining amount of fuel in the fuel cell can be easily detected as a voltage value. It becomes.

  Further, the remaining amount detection mechanism employed in the present invention has a simple configuration and is suitable for downsizing.

  In addition, the movable partition moves as the by-product volume increases, and the sliding contact of the slider moves by the movement of the movable partition. It can be detected reasonably (effectively). Here, the moving of the movable partition wall is made smoother by filling the inside of the by-product containing portion with an absorbent material (such as a superabsorbent polymer) that absorbs the by-product and increases its volume. Can be done. Further, by providing the variable resistor with a guide for restricting the moving direction of the slider, the slider can be moved in a predetermined direction even when the electric device is tilted.

  In addition, when the movable partition wall is pressed by the by-product and moves to the fuel part side, the fuel is efficiently pushed out to the power generation part, and the effect that the fuel can be used up sufficiently is also obtained.

  In addition, the voltage signal indicating the remaining amount of fuel has characteristics similar to the characteristics of the output voltage with respect to the time of the secondary battery. Detection technology) can also be applied to a fuel cell remaining amount detection technology.

  In addition, when a secondary battery and a fuel cell are mounted on an electrical device and the secondary battery is used as a direct power source, and the fuel cell is used for backup of the secondary battery, the remaining amount of the secondary battery And the remaining amount of the fuel cell can be detected by a common remaining amount detector, and the configuration of the detector can be simplified.

  In addition, by applying the fuel remaining amount detection technique of the present invention to a methanol direct fuel cell, an easy-to-use power supply system that can be mounted on a small and light device can be realized.

  Further, according to the present invention, when the remaining amount of fuel is automatically detected using the voltage indicating the remaining amount of fuel, which is output from the fuel cell of the present invention, and the amount of fuel becomes small. To that user can be notified without delay. Therefore, the user can know that the amount of fuel has become small, and can perform fuel filling and fuel cell replacement at an appropriate timing.

  According to the present invention, in a mobile terminal such as a mobile phone terminal, the degree of battery consumption can be shown to the user at an appropriate timing, and user convenience is improved.

  First, the difference in the output voltage characteristics between the fuel cell and the secondary battery will be described.

  FIG. 8 is a characteristic diagram showing changes in output voltage with respect to discharge time of a methanol direct fuel cell and a lithium ion secondary battery. In the figure, a characteristic line S1 indicated by a dotted line indicates the characteristic of the output voltage of the lithium ion secondary battery. A characteristic line S2 indicated by a solid line indicates the characteristics of the output voltage of the fuel cell. In addition, this characteristic is a characteristic in the case of 1c discharge (discharge completion in 1 hour).

  As shown in the figure, the lithium ion secondary battery exhibits a characteristic that the output voltage monotonously decreases with respect to the discharge time. On the other hand, it can be seen that the output voltage of the fuel cell is substantially constant with respect to the discharge time and exhibits constant voltage characteristics. In the present invention, utilizing the constant voltage property of the output voltage of the fuel cell, the resistance in the slide type variable resistor is biased, the voltage dividing point is determined by the slider, the constant voltage is divided by resistance, and the voltage is A configuration of taking out through a slider is adopted.

Next, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)

  FIG. 1 is a block diagram showing an outline of the configuration of a fuel cell (methanol direct fuel cell) according to the present invention and an example of a configuration for detecting / notifying the remaining amount of fuel in a portable device equipped with the fuel cell. .

  The fuel cell 100 is mounted on a portable device such as a mobile phone terminal, and includes a fuel tank 110 (comprising a fuel unit 112 and a by-product recovery unit 114), a power generation unit 120, and output voltage terminals (121, 122). ) And a fuel remaining amount detection terminal 123.

  The power supply voltage obtained from the output voltage terminals (121, 122) of the fuel cell 100 is supplied to the internal circuit 130 of the portable device. Further, the power supply voltages (A1, A2) obtained from the output voltage terminals (121, 122) of the fuel cell 100 are also supplied to the byproduct recovery unit 114.

  Further, a voltage signal (A 3) indicating the remaining amount of fuel is supplied from the by-product recovery unit 114 to the remaining amount detection terminal 123. The remaining amount detection signal (voltage signal) obtained from the remaining amount detection terminal 123 is given to the remaining amount detection unit 140 provided in the portable device.

  When the remaining amount detection unit 140 detects that the remaining fuel amount is equal to or less than a predetermined threshold value, the notification unit 150 is driven, and it is indicated to the user by light, sound, warning display, etc. that the remaining fuel is low. Informed.

  FIG. 2 is a diagram for explaining the basic structure of the power generation unit shown in FIG. 1 and its power generation operation.

  The chemical change that occurs in the power generation unit 120 is as described in (Formula 1) and (Formula 2).

  As shown in the drawing, the negative electrode 11 oxidizes the fuel to extract electrons and protons from the fuel. The positive electrode 12 is for purifying water by reacting electrons generated by reducing oxygen with protons generated at the negative electrode. The electrolyte layer 13 is for transporting protons generated in the negative electrode 11 and is made of a material that does not have electron conductivity and can transport protons.

  Reference numeral 14 denotes a catalyst layer, and a catalyst for accelerating each chemical reaction is disposed between the negative electrode 11 and the positive electrode 12 and the electrolyte layer.

  A fuel for the negative electrode is an aqueous methanol solution. The fuel is supplied from the fuel part 112 of FIG. 1 as fuel that is oxidized at the negative electrode through the fuel supply port 11a. Protons generated by the negative electrode 11 are transported through the electrolyte layer and conducted to the positive electrode.

  In the positive electrode, air is supplied from an air supply port 12a (not shown in FIG. 1), and protons generated in the negative electrode are reacted with oxygen contained in the air to generate water.

  Further, the electrons move from the negative electrode terminal 11b installed at the end of the negative electrode to the positive electrode through the positive electrode terminal 12b installed at the end of the positive electrode 12, thereby generating a direct current to the load. Power is being supplied.

  As a result, water is produced by combining with oxygen molecules supplied from the positive electrode. As a result, water is generated from the positive electrode and carbon dioxide is generated from the negative electrode. Water is discharged from the discharge port 12c and carbon dioxide is discharged from the exhaust port 11c.

  FIG. 3 is a diagram showing an example of a specific internal configuration of the fuel cell shown in FIG. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals.

  As illustrated, the fuel tank 110 has a double structure including an inner tank P1 and an outer tank P2.

  The inner tank P1 includes a fuel portion 112, a by-product storage portion 114, and a movable partition wall 16 that separates the two.

  A resistor 119 made of a carbon film resistor or the like is formed on the main surface of the upper inner wall of the outer tank P2. A slider 117 having a sliding contact (portion indicated by a black circle in the figure) is formed on the main surface of the resistor 119. The slider 117 is electrically connected to the fuel detection terminal 123.

  The end of the slider 117 opposite to the sliding contact is connected (fixed) to the upper end of the movable partition wall 116.

  The resistor 119 and the slider 117 constitute a slide type variable resistor.

  The output voltage of the fuel cell 100 is applied as a power supply voltage (constant voltage) across the resistor 119 of the slide type variable resistor. The resistor 119 is divided into two at the position of the sliding contact point of the slider 117 (that is, the constant voltage is divided by two resistors), and the divided voltage is It is taken out through the slider 117 and the fuel detection terminal 123.

  Since the output voltage of the fuel cell 100 can be regarded as substantially constant with respect to the discharge time as shown in FIG. 8, the voltage taken out via the slider 117 is only at the position of the slider 117. Will change depending on.

  When power generation by the fuel cell proceeds, the volume of the by-product (water) in the by-product storage unit 114 increases, and the movable partition wall 116 is pressed accordingly. (That is, the movable partition wall 116 moves to the fuel section side as indicated by the dotted arrow in FIG. 3), and the sliding contact of the slider 117 is moved by the movement of the movable partition wall 112. The voltage (voltage divided by resistance) taken out via the slider 117 changes.

  An increase in by-products means that the remaining amount of fuel has decreased due to power generation by the fuel cell. As described above, the position of the slider of the slide type variable resistor changes as the by-product (volume) increases, and the value of the voltage taken out via the slider also changes with the displacement. As a result, the remaining amount of fuel can be observed (detected) as a voltage value. The structure of the remaining amount detection mechanism is simple and can be applied to a small fuel cell.

  Further, in order to accurately convert the volume increase of the by-product (water) into the displacement of the movable partition wall 116 (in order to smoothly move the movable partition wall 116), The inside is filled with an absorbent material (such as a superabsorbent polymer) that absorbs the by-product (water) and greatly increases its volume.

  In addition, even when the portable device on which the fuel cell is mounted is tilted, the above-mentioned variable resistor has a restriction on the moving direction of the slider so that the movable partition wall 116 moves in a predetermined direction. (The structure of the variable resistor will be described with reference to FIG. 5).

  Further, when the movable partition wall 116 is moved by the pressure from the by-product storage unit 114, the volume of the fuel unit 112 is reduced by that amount, and the fuel (methanol aqueous solution) is efficiently pushed out to the power generation unit 120. The effect that it can be used up sufficiently is also acquired.

  4A to 4C are cross-sectional views of the main part of the fuel cell for explaining the relationship between the increase of by-products accompanying the progress of power generation and the displacement of the slider.

  The by-product storage unit 114 is provided with a retractable storage container (R), and water, which is a by-product generated by the power generation of the fuel cell, is stored in the storage container (R). Is done. The storage container (R) is filled with an absorbent material (not shown) made of a highly water-absorbing polymer or the like.

  As shown in FIG. 4A, in the initial state, since the water as a by-product is not accumulated in the storage container (R), the movable partition wall 116 is located at the right end. The resistance value of the resistor interposed between the high voltage side terminal 122 and the slider 117 is R1.

  As shown in FIG. 4B, when power generation proceeds, water as a by-product is accumulated in the storage container (R) and the volume rapidly increases. It is pushed to the side (left side in the figure) and moves. The resistance value of the resistor interposed between the high voltage side terminal 122 and the slider 117 changes to R2.

  As shown in FIG. 4 (c), when power generation further proceeds, a large amount of water as a by-product is accumulated in the storage container (R), and the movable partition wall 116 further moves to the fuel section 112 side (in the figure). Move to the left). The resistance value of the resistor interposed between the high voltage side terminal 122 and the slider 117 changes to R3.

  A constant voltage output from the fuel cell 100 is applied to both ends of the resistor 119, and the resistance voltage dividing point is moved by the movement of the slider 117, and the voltage output from the fuel remaining amount detection terminal 123 is Change. That is, as the power generation time becomes longer, the voltage (remaining amount detection voltage) output from the remaining fuel amount detection terminal 123 decreases. Therefore, the voltage signal indicating the remaining amount of fuel can have the same monotonic decrease characteristic as the characteristic line S1 of the secondary battery indicated by the dotted line in FIG.

  This makes it possible to apply the remaining amount detection technology (provided remaining amount detection technology) by detecting the output voltage of the secondary battery to the remaining amount detection technology of the fuel cell.

  In addition, when a secondary battery and a fuel cell are mounted on an electrical device and the secondary battery is used as a direct power source, and the fuel cell is used for backup of the secondary battery, the remaining amount of the secondary battery And the remaining amount of the fuel cell can be detected by a common remaining amount detector, and the configuration of the detector can be simplified.

  FIG. 5 is a plan view showing an example of the configuration of the slide type variable resistor.

  As shown in the figure, a slit (guide) 29 is formed in the center of the strip-shaped ceramic substrate 23 along the longitudinal direction.

  On the ceramic substrate 23, a carbon film resistor 28 (corresponding to the resistor 119 in the above-mentioned drawing) printed in a straight line is provided.

  Reference numerals 18a to 18c are conductive metal thin plates (terminals) having a silver paste applied to the base. A high level output voltage of the fuel cell 100 is applied to the conductive metal thin plate 18 a via a terminal 122, and a low level output voltage is connected to the conductive metal thin plate 18 b via a terminal 121. A remaining amount detection terminal 123 is connected to the conductive metal thin plate 18c.

  Further, a thin metal piece 24 (corresponding to the slider 117 in the above-mentioned drawings) is slidably fitted into the slit (guide) 29.

  The metal piece 24 (that is, the slider 117) can move along the slit (guide) 29 while being in contact with the carbon film resistor 28 and the conductive metal thin plate 18c. As described above, the metal piece 24 (that is, the slider 117) is connected to the movable partition wall 116, and moves in the direction of the dotted arrow in the drawing in conjunction with the movement of the movable partition wall 116.

  As the slider 24 moves, the position of the resistance voltage dividing point changes and the voltage decreases monotonously. The change in the voltage level can be detected via the remaining amount detection terminal 123.

The slide-type variable resistor is a proven component widely used in electrical equipment, has high reliability, can maintain high output voltage accuracy, and has a simple configuration. Suitable for miniaturization.
(Second Embodiment)

  FIG. 6 is a perspective view showing the appearance of a foldable mobile phone terminal that uses a fuel cell as a power source (battery). In FIG. 6, the configuration around the fuel tank is denoted by the same reference numerals as in the previous drawings.

  As illustrated, the foldable mobile phone terminal 300 includes an upper casing 350 and a lower casing 352. The lower housing 352 is provided with a lid 354, and a recess (housing portion for the fuel tank 110) for housing the fuel tank 110 is provided under the lid 354. Under this recess, a power generation unit 120 of the fuel cell is provided.

  As described above, the fuel tank 110 is separated into the fuel part and the by-product containing part by the movable partition wall 116, and each part is provided with a projection K1 for injecting fuel and for injecting a by-product (water). A protrusion K2 is provided.

  In addition, recesses Q1 and Q2 corresponding to the protrusions (K1 and K2) are provided in the recess for storing the fuel tank 110 (the storage portion of the fuel tank 110).

  FIG. 7 is a block diagram showing a configuration of main parts inside the mobile phone terminal shown in FIG. For simplification of explanation, in FIG. 7, the same reference numerals are given to the portions common to the above-mentioned drawings.

  The mobile phone terminal 300 includes a methanol direct fuel cell 100, a DC-DC converter (DC level converter) 310, and an internal circuit of the mobile phone terminal that operates with a power supply voltage supplied from the DC-DC converter 310. 320 and a power supply control unit 330 (including a remaining amount detection unit 332, a remaining amount detection management unit 334, a voltage control unit 336, and a notification unit 338).

  The methanol direct fuel cell 100 is provided with a switch SW1, and this switch SW1 is turned on only at the timing of detecting the remaining amount of fuel, and is turned off during other periods, whereby the resistor 119 is turned on. , Always prevents current from flowing, reducing power consumption. The on / off state of the switch SW1 is controlled by the remaining amount detection management unit 334 in the power supply control unit 330.

  The remaining amount detection unit 332 in the power supply control unit 330 determines the remaining amount of fuel (methanol aqueous solution) of the fuel cell 100 based on the level of the voltage output from the remaining amount detection terminal 23 of the fuel cell 100. When the voltage level falls below a predetermined threshold value, the remaining amount detection unit 332 sends a signal indicating that the remaining amount of fuel is low to the remaining amount detection management unit 334. The management unit 334 drives the notification unit 338 and notifies the user that the remaining amount of the fuel cell is low by sound, light, warning display, or the like.

  Therefore, the user can know that the amount of fuel has become small, and can perform fuel filling and replacement of the fuel cell at an appropriate timing.

  The voltage control unit 336 of the power supply control unit 330 appropriately adjusts the level of the power supply voltage supplied to the internal circuit 320 of the mobile phone terminal by controlling the direct current level conversion operation of the DC-DC converter 310.

  As described above, according to the present invention, the remaining amount of the fuel cell is automatically detected, and when the amount of fuel becomes small, it is possible to notify the user to that effect without delay. Accordingly, the user can know that the amount of fuel has become small, and can perform fuel filling and replacement of the fuel cell at an appropriate timing, thereby improving the convenience of the mobile phone terminal.

  The present invention is not limited to the above-described embodiment, and various modifications and applications are possible. For example, the slide type variable resistor may be separately provided outside the fuel tank. The present invention can also be applied to fuel cells other than methanol direct fuel cells.

  As described above, according to the present invention, the fact that the output voltage of the fuel cell exhibits a constant voltage characteristic is actively utilized, and the above-described constant variable resistor, which is a proven electric element, is used. The configuration is such that the voltage obtained by dividing the voltage by resistance is taken out via the slider, and the slider is displaced as the by-products increase. It can be easily detected as a value.

  Further, the remaining amount detection mechanism employed in the present invention has a simple configuration and is suitable for downsizing.

  In addition, the movable partition moves as the by-product volume increases, and the sliding contact of the slider moves by the movement of the movable partition. It can be detected reasonably (effectively). Here, the moving of the movable partition wall is made smoother by filling the inside of the by-product containing portion with an absorbent material (such as a superabsorbent polymer) that absorbs the by-product and increases its volume. Can be done. Further, by providing the variable resistor with a guide for restricting the moving direction of the slider, the slider can be moved in a predetermined direction even when the electric device is tilted.

  In addition, when the movable partition wall is pressed by the by-product and moves to the fuel part side, the fuel is efficiently pushed out to the power generation part, and the effect that the fuel can be used up sufficiently is also obtained.

  In addition, the voltage signal indicating the remaining amount of fuel has characteristics similar to the characteristics of the output voltage with respect to the time of the secondary battery. Detection technology) can also be applied to a fuel cell remaining amount detection technology.

  In addition, when a secondary battery and a fuel cell are mounted on an electrical device and the secondary battery is used as a direct power source, and the fuel cell is used for backup of the secondary battery, the remaining amount of the secondary battery And the remaining amount of the fuel cell can be detected by a common remaining amount detector, and the configuration of the detector can be simplified.

  In addition, by applying the fuel remaining amount detection technique of the present invention to a methanol direct fuel cell, an easy-to-use power supply system that can be mounted on a small and light device can be realized.

  Further, according to the present invention, the remaining amount of fuel is automatically detected by using the voltage indicating the remaining amount of fuel output from the fuel cell of the present invention in the electric device. It is possible to notify the user of the device to that effect without delay. Therefore, the user can know that the amount of fuel has become small, and can perform fuel filling and fuel cell replacement at an appropriate timing.

  According to the present invention, in a mobile terminal such as a mobile phone terminal, the degree of battery consumption can be shown to the user at an appropriate timing, and user convenience is improved.

  The present invention makes it possible to detect the remaining amount of fuel in the fuel cell by a voltage signal, as in the case of the secondary battery, and has the effect of promoting the application of the power system by the fuel cell to a small device. It can be widely used in electric devices such as portable terminal devices such as mobile phone terminals and PDAs, electronic still cameras, and laptop computers.

1 is a block diagram showing an outline of the configuration of a fuel cell (methanol direct fuel cell) according to the present invention, and an example of a configuration for detecting / notifying the remaining amount of fuel in a portable device equipped with the fuel cell. 1 is a diagram for explaining the basic structure of the power generation unit shown in FIG. 1 and its power generation operation. The figure which shows the example of a specific internal structure of the fuel cell shown by FIG. (A)-(c) is sectional drawing of the principal part of the fuel cell for demonstrating the relationship between the increase in the by-product accompanying progress of electric power generation, and the displacement of a slider. The top view which shows an example of a structure of a slide type variable resistor A perspective view showing the appearance of a foldable mobile phone terminal that uses a fuel cell as a power source (battery) The block diagram which shows the principal part structure inside the mobile telephone terminal shown by FIG. Characteristic diagram showing change of output voltage with respect to discharge time of methanol direct fuel cell and lithium ion secondary battery

Explanation of symbols

11a Fuel (methanol aqueous solution) supply port 11 Negative electrode 11b Negative electrode terminal 11c Exhaust port 12 Positive electrode 12b Positive electrode terminal 13 Electrolyte layer 14 Catalyst 12c Byproduct (water) injection port 18a to 18c Conductive metal thin plate 28 Carbon film resistor 23 Ceramic substrate 24 Metal piece functioning as a slider 100 Fuel cell 110 Fuel tank 112 Fuel part 114 By-product storage part 116 Movable partition wall 117 Slider 119 Resistance (carbon film resistor etc.)
DESCRIPTION OF SYMBOLS 120 Power generation part 121,122 Output voltage application terminal of fuel cell 123 Remaining amount detection terminal 130 Internal circuit of portable device 140 Remaining amount detection part 150 Notification part 300 Mobile phone terminal 310 DC-DC converter 320 Internal circuit of mobile phone terminal 330 Power supply Control unit 332 Remaining amount detection unit 334 Remaining amount detection management unit 336 Voltage control unit 338 Notification unit 350 Upper housing 352 Lower housing 354 Lid K1, K2 Fuel injection port and by-product (water) injection port Q1 , Q2 Recesses corresponding to K1, K2 P1 Inner tank P2 Outer tank R By-product storage container

Claims (6)

A fuel cell comprising a power generation unit that generates power by a combustion reaction of fuel, a fuel unit that stores the fuel, and a by-product storage unit that stores a by-product generated along with power generation,
A resistor connected between the output voltage terminals of the fuel cell; and a movable electrode terminal that moves while contacting the main surface of the resistor as the by-products generated by the power generation of the fuel cell increase. Variable resistor,
A fuel cell comprising: a fuel remaining amount detection terminal for outputting a voltage extracted via the movable electrode terminal of the variable resistor to the outside as a fuel remaining amount detection signal in the fuel section. The fuel cell according to claim 1, wherein
The movable electrode terminal is a slider having a sliding contact that moves while contacting the main surface of the resistor, and the variable resistor is a slide-type variable resistor,
A fuel cell configured to output, to the outside, a voltage taken out through the slider of the slide type variable resistor as a fuel remaining amount detection signal in the fuel section. The fuel cell according to claim 1, wherein
A movable partition wall is provided in the fuel tank to separate the fuel unit and the by-product storage unit, and the movable partition wall has a predetermined direction as the amount of the by-product stored in the by-product storage unit increases. And one end of the slider opposite to the sliding contact is connected to the movable partition wall. A fuel cell according to any one of claims 1 to 3,
The fuel cell is a methanol direct fuel cell that generates power by a chemical reaction between an aqueous methanol solution and oxygen to generate water as the by-product. 5. A fuel remaining amount detection unit configured to detect the remaining amount of fuel in response to the remaining amount detection signal output from the remaining fuel amount detection terminal of the fuel cell according to claim 1. ,
Based on the detection result, a notification unit for notifying the user of fuel remaining amount information;
Having electrical equipment. The electric device according to claim 5,
The electric device is a portable terminal device.

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