JP2008159363A - Portable fuel cell and control method of portable fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable fuel cell, and a control method of the portable fuel cell which can carry out fuel residue detection and fuel density detection by one sensor and can start and maintain stable power generation even if the fuel cell is placed in any direction. <P>SOLUTION: The portable fuel cell is provided with an MEA stack 100 connecting MEAs in multi-steps being membrane-electrode conjugants having structures each pinching an electrolyte membrane with a fuel electrode and an oxidant electrode, and equipped with a fuel flow channel for supplying fuel to electrodes of the MEAs, a fuel tank 102 for temporarily storing fuel supplied to the MEA stack 100, a fuel cartridge 104 connected to the fuel tank 102 in free detachment, a pump 107 for supplying fuel from the fuel cartridge 104 to the fuel tack 102, a density sensor 101 arranged in the fuel flow channel for detecting the density of fuel, and a control unit 103 for controlling the pump 107 based on an output value of the density sensor 101. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a portable fuel cell and a method for controlling the portable fuel cell, and more particularly to fuel remaining amount detection using a fuel concentration sensor required for fuel supply control.

  A fuel cell is a power generator that generates power by electrochemically reacting a fuel fluid such as hydrogen gas or methanol with an oxidizing fluid (oxygen contained in air). For example, in the case of a solid polymer fuel cell, each power generator part has a structure in which an electrolyte membrane made of a solid polymer is sandwiched between an oxygen side electrode and a fuel side electrode, and oxygen is supplied to the oxygen side electrode. Air is supplied for supply, fuel fluid is supplied to the fuel side electrode, and power generation is performed by an electrochemical reaction.

  In recent years, fuel cells using hydrogen gas as fuel have attracted attention as a clean power source that does not pollute the environment because the product generated by power generation is water. For example, it is expected to be put into practical use in large systems such as electric vehicles and residential power supply systems, while taking advantage of the small size and light weight of solid polymer fuel cells, for example, notebook personal computers Applications as a power source for portable electronic devices are also being studied. The power generation part of the fuel cell is called an electrolyte membrane / electrode assembly or MEA (Membrane and Electrode Assembly), and a fuel cell having a stack structure is formed by electrically connecting a plurality of power generation cells in series. Yes.

  In a fuel cell used for such a portable electronic device or the like, a direct methanol fuel cell (DMFC) system using methanol, which is easy to handle as compared with hydrogen gas, is considered advantageous. In this direct methanol fuel cell system, power generation is performed by mounting a fuel cartridge filled with methanol in an electronic device and supplying the fuel in the fuel cartridge to the fuel cell.

In direct methanol fuel cell power generation,
Anode electrode: CH ₃ OH + H ₂ O → 6H ++ 6e ⁻ + CO ₂
^{Cathode: 6H + + 6e - + 1.5O} 2 → 3 H 2 O
Reaction occurs.

  That is, protons, electrons, and carbon dioxide are generated at the anode electrode, and the electrons are used for power generation by passing through an external circuit, and the carbon dioxide is discharged into the atmosphere. Protons reach the cathode electrode through the proton conductive electrolyte. On the other hand, in the cathode electrode, protons that reach from the anode electrode, electrons that have passed through the external circuit, and oxygen in the air react to generate water. Therefore, the product of DMFC is theoretically only water and carbon dioxide and is discharged into the atmosphere as a clean product that is friendly to the environment.

  In the direct methanol fuel cell system, especially the active type that supplies fuel using auxiliary equipment, the absolute amount of liquid fuel and the concentration control of methanol contained in it are important factors for stable and reliable power generation. is there. When the methanol concentration is too low, a sufficient amount of fuel is not supplied to the MEA, which not only deteriorates the power generation performance but also seriously degrades the MEA.

  If the methanol concentration is too high, a crossover phenomenon may occur in which methanol is not oxidized at the anode electrode but permeates to the cathode electrode, resulting in a decrease in power generation efficiency or elution of the catalyst electrode or electrolyte material into the fuel. The problem of end up occurs. On the other hand, when the amount of fuel is small, the anode electrode deteriorates because it tries to oxidize substances other than fuel when current is drawn when methanol as a reducing agent is not sufficiently supplied as in the case where the concentration of fuel is low. Will eventually lead to degradation / damage of the MEA.

Therefore, it is required to control the methanol concentration and its absolute amount in the liquid fuel. For this purpose, a concentration sensor and a remaining fuel amount sensor are provided in the fuel cell system to control the concentration and amount of methanol contained in the liquid fuel. It is being grasped and controlled. As a method for measuring the methanol concentration, a method for calculating the fuel concentration from the voltage value of the MEA (see Patent Document 1 and FIG. 3), and a fuel concentration is calculated by using a difference in ultrasonic propagation speed. Method (see Patent Document 2), a method for calculating the concentration from a change in the density (specific gravity) of the fuel, a method for calculating the concentration of the fuel from the temperature rise due to the MEA crossover, and a concentration of the fuel from the difference in capacitance And a method for calculating the concentration of fuel by using an optical refractive index, and an example in which the concentration is measured by using a limiting current at a low concentration has been reported. On the other hand, for the fuel level sensor, when detecting the position of the liquid level, such as a method of detecting a change in capacitance, a method of detecting the remaining level based on the reflection position of the liquid level by an optical method, or a position detection by float There are also many methods for detecting the weight of the fuel.
Japanese Patent Publication No. 6-26132 JP 11-23541 A

  Normally, when starting a fuel cell, it is necessary to start power generation after a liquid fuel of an appropriate concentration is sufficiently supplied to the MEA. However, even if the concentration of the fuel is detected by the concentration sensor, if the fuel is not continuously supplied to the concentration sensor, it is impossible to measure the concentration of the fuel and determine the amount and concentration of the added fuel. is there. Therefore, the fuel cell start-up sequence starts with detecting the remaining amount of fuel and supplying the fuel with an appropriate concentration if the fuel is insufficient, and then measuring the concentration with the concentration sensor to obtain the appropriate concentration. When the fuel is supplied from the fuel cartridge so that the amount of fuel reaches the specified value, the power generation preparation is completed.

  Here, as a method of detecting the remaining amount of liquid fuel, the most reliable value can be obtained by measuring its weight, and a stationary type that can fix the installation direction of the fuel cell is sufficiently practical. However, in the case of a small fuel cell applied to a portable device, it is necessary to be able to generate power regardless of the direction in which the fuel cell is placed, and it is difficult to measure the weight of the entire power generation system or a part thereof. In addition, the fuel is replenished from the fuel cartridge, the mixed fuel is supplied to the fuel cell stack, and the amount of fuel relative to the total volume of the fuel tank receiving the fuel discharged from the fuel cell stack is measured. There are various methods for detecting the fuel level in the tank, such as a capacitance type, an optical type, and a magnetic type. In order to measure the amount of fuel in any direction, an inclination sensor and a plurality of level sensors are used. Need to be calculated in combination, increasing the load on the CPU power in the control unit and increasing the cost.

  Accordingly, in view of the above problems, the present invention provides a portable fuel cell capable of detecting the remaining amount of fuel and detecting the fuel concentration with a single sensor, and stably starting and maintaining power generation regardless of the direction of the fuel cell. It is an object of the present invention to provide a control method for a portable fuel cell.

  In order to achieve the above object, the portable fuel cell of the present invention has a multi-stage connection of MEAs, which are membrane / electrode assemblies having a structure in which an electrolyte membrane is sandwiched between a fuel electrode and an oxidizer electrode, and fuel is supplied to the electrode portion of the MEA. A fuel cell stack having a fuel flow path for supplying, a fuel tank for temporarily retaining fuel supplied to the fuel cell stack, a fuel cartridge detachably connected to the fuel tank, and fuel from the fuel cartridge Supply means for supplying to the fuel tank, a concentration sensor installed in the fuel flow path for detecting the concentration of the fuel, and a control unit for controlling the supply means based on the output value of the concentration sensor.

  In the portable fuel cell according to the present invention, the control unit controls the supply means based on the output value of the concentration sensor for the amount of fuel supplied from the fuel cartridge to the fuel tank. And not. That is, the portable fuel cell of the present invention can detect the remaining amount of fuel and detect the fuel concentration with one sensor.

  The concentration sensor of the portable fuel cell according to the present invention may be installed in a fuel discharge channel through which fuel is discharged from the fuel cell stack. In the operation of the fuel cell, it is highly likely that operation at a low concentration particularly damages the MEA performance. Therefore, the reliability of the entire system can be improved by measuring the concentration of the fuel in the fuel discharge flow path where the concentration of the fuel becomes the lowest and controlling the operating state of the fuel cell based on this information. .

  In the fuel tank of the portable fuel cell of the present invention, there are a fuel inlet that is an end portion on the fuel tank side of a flow path for supplying fuel from the fuel cartridge to the fuel tank, and from the fuel cell stack to the fuel tank. A fuel discharge port which is a fuel tank side end of a fuel discharge channel which is a flow path of the fuel discharged, and a fuel tank side end of a channel for supplying fuel from the fuel tank to the fuel cell stack And a fuel suction port. The distance between the fuel inlet and the fuel outlet is set to be shorter than the distance between the fuel inlet and the fuel inlet and the distance between the fuel inlet and the fuel outlet. ing. The fuel cell can be stably operated by installing the fuel discharge port through which the low concentration fuel is discharged and the fuel injection port through which the high concentration fuel is supplied at positions away from the fuel intake port.

In addition, the fuel inlet of the portable fuel cell of the present invention may be located approximately at the center of gravity of the fuel tank.
By positioning the fuel inlet at the center of gravity of the fuel tank, it is possible to prevent the fuel supply from stagnation if there is more than half the capacity of the fuel tank regardless of the posture of the fuel cell. Further, even when the attitude of the fuel cell changes, the time during which the fuel supply is delayed can be minimized.

  Further, the fuel discharge port of the portable fuel cell of the present invention is disposed at a position away from the fuel intake port by a distance of at least 1/4 or more of the maximum length of the diagonal line of the fuel tank having a rectangular cross section. It may be a thing.

  Also, the fuel cartridge of the portable fuel cell of the present invention stores at least two types of fuel having different concentrations, and the supply means supplies the fuel of each concentration individually from the fuel cartridge to the fuel tank. May be. In this case, it is possible to inject an appropriate amount of fuel at an appropriate concentration as necessary, and the concentration of the fuel can be continuously changed, so that the followability to the external environment change is high and the reliability is excellent. It is possible to provide a portable fuel cell.

  Further, the concentration sensor of the portable fuel cell of the present invention may detect a change in the density of the fuel or a change in the specific gravity of the fuel, and further detect a change in the speed of sound propagating in the fuel. There may be. By using a concentration sensor based on these detection methods, an output value from the concentration sensor can be obtained even when the fuel concentration is 100% or more.

  The control method of the portable fuel cell of the present invention is the control method of the portable fuel cell of the present invention, and when the output value of the concentration sensor continuously shows a value of 100% or more, the control unit It is determined that there is no fuel in the fuel cell stack, and the supply means is controlled so as to supply a predetermined amount of fuel from the fuel cartridge to the fuel tank.

  Further, according to the control method of the portable fuel cell of the present invention, when the output value of the concentration sensor vibrates between a value having a concentration of 100% or more and a value having a concentration of less than 100%, the control unit causes the oscillation cycle of the output value to be The amount of fuel in the fuel cell stack is estimated according to the amount of fuel, and the fuel is supplied from the fuel cartridge to the fuel tank in a prescribed amount based on the estimated amount of fuel and the output value of the concentration sensor less than 100%. The supply means may be controlled.

  As described above, the control method for the portable fuel cell according to the present invention detects not only the fuel concentration but also the remaining amount of fuel by the concentration sensor, so that no sensor other than the concentration sensor is required for supplying the fuel.

Further, according to the portable fuel cell control method of the present invention, at least two kinds of fuel having different concentrations are stored in the fuel cartridge, and the output value of the concentration sensor continuously indicates a value of 100% or more. In this case, the control unit determines that there is no fuel in the fuel cell stack, and controls the supply means to supply each concentration of fuel from the fuel cartridge to the fuel tank in a specified concentration and a specified amount. Also good. in this case,
Using multiple types of fuel concentration, fuel can be injected in the proper amount at the right concentration as needed, and the fuel concentration can be continuously changed, so it can follow changes in the external environment. It is possible to provide a portable fuel cell having high reliability and excellent reliability.

  The fuel concentration sensor can be used to detect the remaining amount of fuel, so there is no need for a separate fuel remaining amount sensor, and the amount of fuel in the fuel cell stack can be measured regardless of the orientation of the fuel cell. Since estimation is possible, it is possible to stably maintain power generation by the fuel cell.

Next, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a configuration diagram of a portable fuel cell according to the present embodiment. FIG. 2 is a diagram showing the positional relationship between the fuel inlet, the fuel outlet, and the fuel inlet in the portable fuel cell of this embodiment. FIG. 3 is a graph showing an example of output fluctuation of the density sensor.

  In the MEA stack 100 in which MEAs, which are membrane / electrode assemblies having a structure in which an electrolyte membrane is sandwiched between a fuel electrode and an oxidizer electrode, are connected in series or in parallel, oxygen in the air is supplied to the cathode side by a blower fan 105. On the anode side, the liquid fuel stored in the fuel tank 102, or methanol in the DMFC, is supplied by the pump 106. A fuel cartridge 104 that stores fuel and is detachable is connected via a pump 107. The fuel in the fuel cartridge 104 is supplied to the fuel tank 102 by the operation of the pump 107 when the liquid fuel in the fuel tank 102 falls below a specified value. When supplying fuel from the fuel cartridge 104 side, the internal pressure of the fuel tank 102 increases, and an internal pressure adjustment mechanism 108 is provided to avoid damage to the MEA due to the increase in fuel supply pressure.

  Further, a concentration sensor 101 for detecting the specific gravity, density or sound speed of the liquid fuel is provided in the fuel discharge passage for returning the fuel from the MEA stack 100 to the fuel tank 102. The control unit 103 operates accessories such as the blower fan 105 and the pumps 106 and 107 according to the output value of the concentration sensor 101. The concentration sensor 101 is provided in the fuel discharge channel for the following reason. In the operation of the fuel cell, it is highly likely that operation at a low concentration particularly damages the MEA performance. That is, it is for improving the reliability of the entire system by measuring the fuel concentration in the fuel discharge flow path where the fuel concentration is the lowest and controlling the operating state of the fuel cell based on this information.

  Next, the positional relationship between the fuel inlet, the fuel outlet, and the fuel inlet will be described with reference to FIG. Although the layout is different from the portable fuel cell shown in FIG. 1, it is the same portable fuel cell.

  A fuel inlet 120, which is an end portion on the fuel tank 102 side of a flow path for supplying fuel in the fuel tank 102 to the MEA stack 100, is disposed at a substantially center of gravity of the fuel tank 102. By disposing the fuel inlet 120 at the center of gravity of the fuel tank 102, the fuel supply will not be delayed if there is more than half of the capacity of the fuel tank 102 regardless of the posture of the fuel cell. Further, even when the attitude of the fuel cell changes, the time during which the fuel supply is delayed can be minimized.

  A fuel discharge port 116, which is an end portion of the fuel discharge channel, which is a flow path of fuel discharged from the MEA stack 100 to the fuel tank 102, on the fuel tank 102 side is disposed at a position away from the fuel intake port 120. Yes. A fuel inlet 117, which is an end portion on the fuel tank 102 side of a flow path for supplying fuel from the fuel cartridge 104 to the fuel tank 102, is also disposed at a position away from the fuel inlet 120. The reason why the fuel discharge port 116 and the fuel injection port 117 are installed at positions apart from the fuel intake port 120 is to make the fuel concentration in the fuel tank 102 as uniform as possible and to operate the fuel cell stably. is there. A low concentration fuel is discharged from the fuel discharge port 116. On the other hand, high concentration fuel is supplied to the fuel inlet 117. If fuel having a high concentration difference is supplied to the fuel intake port 120 as described above, the concentration sensor 101 detects fuel that is significantly different from the average fuel concentration in the fuel tank 102. Then, based on the detection result of the concentration sensor 101, the auxiliary machines such as the pumps 106 and 107 operate based on the control signal from the control unit 103. However, since the actual fuel concentration fluctuates greatly, the fuel It becomes difficult to operate the battery stably. Therefore, in order to prevent such a problem, the fuel inlet 120 and the fuel inlet 117 are installed at positions away from the fuel inlet 120 as described above.

  The distance between the fuel inlet 120, the fuel outlet 116, and the fuel inlet 117 in the fuel tank 102 is most effective because the fuel inlet 120 is installed at the center of gravity of the fuel tank 102. In the case of the fuel tank 102 having a rectangular cross-sectional shape, the fuel tank 102 is located at the most distant position in the tank, which is approximately a half of the diagonal distance, but if the distance is at least 1/4 of the diagonal distance, a sufficient effect can be obtained. can get. As another effect, by bringing the fuel outlet 116 and the fuel inlet 117 close to each other, it becomes possible to mix the fuels having different concentrations more quickly and uniformly.

  Next, in the direct methanol fuel cell having the configuration shown in FIGS. 1 and 2, a graph showing a typical change in density output value when a density or concentration or a sound speed detection type concentration sensor is used is shown. 3 shows.

  When the operation of the fuel cell is started, the portion where the concentration display exceeds 100% indicates that a substance lighter than 100% methanol, specifically, air is mixed. Therefore, when this value continues continuously for a certain period, the control unit 103 determines that there is no fuel in the MEA stack 100 and starts fuel injection from the fuel cartridge 104.

  On the other hand, the region where the concentration of fuel starts to oscillate indicates that the fuel level in the fuel tank 102 has reached the fuel inlet 115 in a certain posture. In FIG. 3, the output value of the density sensor 101 vibrates between a value of 100% or more and a value within 0% to 100%. At this time, the amount of fuel in the fuel tank 102 has not reached the amount that can stably generate power from the fuel cell, but the fuel supply overshoot can be suppressed by reducing the fuel supply amount per unit time. The volume of the tank 102 can be reduced. The amount of fuel in the MEA stack 100 is estimated according to the fuel concentration oscillation cycle, and the fuel is supplied from the fuel cartridge 104 according to the estimated amount and the output value within 0% to 100% of the concentration sensor. The control unit 103 may control the pumps 106 and 107 so as to supply only a prescribed concentration and amount of fuel. In this case, the control unit 103 stores in advance a map of the estimated fuel amount in the MEA stack 100 corresponding to the fuel concentration oscillation period.

  When the output value of the concentration sensor 101 indicates a concentration within 0% to 100%, fuel supply to the MEA stack 110 is sufficient, and power generation can be started. However, when power generation is actually started from this state, the output of the concentration sensor 101 immediately starts to vibrate due to the fuel decrease due to power generation, so the fuel supply is stopped and power generation is started when a predetermined amount of fuel is further added. Is preferred. Also in this case, the fuel is replenished based on the map of the amount of fuel stored and held in the control unit 103 in advance.

  Note that when the fuel cell attitude is changed after the start sequence as described above is performed, the output of the concentration sensor 101 starts to vibrate when the fuel inlet 115 is not located at the approximate center of gravity of the fuel tank 102. In that case, it is possible to promptly shift to a stable power generation state by performing fuel supply similar to the above-described sequence.

  The concentration detection method using the concentration sensor according to the present embodiment includes a method for calculating the fuel concentration from the voltage value of the MEA, a method for calculating the fuel concentration using the difference in ultrasonic propagation speed, and the fuel density. A method of calculating the concentration from the change in specific gravity, a method of calculating the concentration of fuel from the temperature rise due to MEA crossover, a method of calculating the concentration of fuel from the difference in capacitance, and using an optical refractive index. Alternatively, a method for calculating the fuel concentration may be used.

  In particular, in the case of the present embodiment, the concentration sensor 101 needs to detect a case where the output value exceeds 100%. Therefore, the concentration sensor 101 calculates the concentration from the change in the density (specific gravity) of the fuel, or the inside of the fuel. It is preferable to use a sensor of a type that calculates the concentration from the change in the speed of sound that propagates through. This is because in the case of other sensors, if the output value exceeds 100%, the concentration may not be detected.

As described above, according to the present embodiment, since the remaining fuel amount detection and the fuel concentration detection are performed by one concentration sensor, it is possible to reduce the load on the CPU power in the control unit and reduce the cost. In addition, the fuel inlet is located at the center of gravity of the fuel tank, preventing the fuel supply from stagnation if there is more than half the capacity of the fuel tank, regardless of the attitude of the fuel cell. Can do.
(Second Embodiment)
FIG. 4 is a configuration diagram of the portable fuel cell of the present embodiment.

  The basic fuel cell system configuration of the present embodiment is the same as the configuration shown in FIG. 1, except that the fuel cartridge 204 has a higher concentration of fuel than the concentration during steady operation and a concentration lower than the concentration during steady operation. It differs in that it is divided so that two types of fuel can be stored. The basic start sequence is almost the same as that of the first embodiment described above, but only the concentration of fuel injected from the fuel cartridge 204 is different. In the following description, the same components as those in the first embodiment will be described using the same symbols as those used in the description of the first embodiment.

  Fuel having a concentration higher than that during steady operation of the fuel cartridge 204 is supplied to the fuel tank 102 by operating the pump 107a. On the other hand, fuel having a concentration lower than that during steady operation is supplied to the fuel tank 102 by operating the pump 107b.

  When the fuel cell is started, the output value of the concentration sensor 101 shows a concentration change as shown in FIG. 3, the concentration display shows a value exceeding 100% from the start of the fuel cell, and almost no gas is present in the fuel flow path. When it is determined that is satisfied, the following control is performed. That is, in this case, the control unit 103 controls the pumps 107a and 107b to change the fuel supply ratio between the two types so as to supply the fuel at the concentration for steady power generation. Supply to tank 102.

  Subsequently, when the output value from the concentration sensor 101 starts to vibrate, the control unit 103 controls the pumps 107a and 107b to gradually reduce the fuel supply amount, and further brings the fuel concentration closer to the concentration during steady power generation.

  Finally, after the oscillation of the output value of the concentration sensor 101 has stopped, fuel of the same concentration is added by a specified value to stop the fuel supply, and then power generation is started.

  Further, even when the attitude of the fuel cell changes during steady power generation, it is possible to maintain a stable power generation state by supplying fuel in the same sequence.

  As described above, according to the present embodiment, as in the first embodiment, the remaining fuel amount detection and the fuel concentration detection are performed by one concentration sensor, so that the load on the CPU power in the control unit is reduced and the cost is reduced. Can do. In addition, the fuel inlet is located at the center of gravity of the fuel tank, preventing the fuel supply from stagnation if there is more than half the capacity of the fuel tank, regardless of the attitude of the fuel cell. Can do.

  Further, in the case of the present embodiment, two types of fuel concentrations can be used, an appropriate amount of fuel can be injected as needed, and the fuel concentration can be continuously changed. It is possible to provide a portable fuel cell that has high followability to external environmental changes and excellent reliability.

  In this embodiment, the concentration of the fuel stored in the fuel cartridge is two types, but may be three or more types.

It is a block diagram of the portable fuel cell which shows the 1st Embodiment of this invention. It is a figure which shows the positional relationship of the fuel inlet, the fuel outlet, and the fuel inlet in the 1st Embodiment of this invention. It is a graph which shows the output fluctuation | variation of a density sensor in the 1st Embodiment of this invention. It is a block diagram of the portable fuel cell which shows the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 MEA stack 101 Concentration sensor 102 Fuel tank 103 Control unit 104 Fuel cartridge 105 Blower fan 106, 107, 107a, 107b Pump 108 Internal pressure adjustment mechanism 116 Fuel discharge port 117 Fuel injection port 120 Fuel intake port

Claims (11)

A fuel cell stack having a fuel flow path for connecting MEAs, which are membrane-electrode assemblies having a structure in which an electrolyte membrane is sandwiched between a fuel electrode and an oxidizer electrode, and supplying fuel to the electrode portion of the MEA; ,
A fuel tank for temporarily retaining fuel to be supplied to the fuel cell stack;
A fuel cartridge detachably connected to the fuel tank;
Supply means for supplying fuel from the fuel cartridge to the fuel tank;
A concentration sensor installed in the fuel flow path for detecting the concentration of fuel;
And a control unit for controlling the supply means based on an output value of the concentration sensor. The portable fuel cell according to claim 1, wherein the concentration sensor is installed in a fuel discharge channel through which fuel is discharged from the fuel cell stack. In the fuel tank, a fuel inlet that is an end portion on the fuel tank side of a flow path for supplying fuel from the fuel cartridge to the fuel tank, and discharge from the fuel cell stack to the fuel tank A fuel discharge port which is an end portion on the fuel tank side of a fuel discharge channel which is a fuel flow path, and an end on the fuel tank side of a flow path for supplying fuel from the fuel tank to the fuel cell stack A fuel inlet that is a portion, and a distance between the fuel inlet and the fuel outlet is a distance between the fuel inlet and the fuel inlet, and a distance between the fuel inlet and the fuel inlet. The portable fuel cell according to claim 1, wherein the portable fuel cell is shorter than a distance between the fuel discharge port. The portable fuel cell according to claim 3, wherein the fuel suction port is located at a substantially center of gravity of the fuel tank. 5. The fuel discharge port according to claim 4, wherein the fuel discharge port is disposed at a position separated from the fuel suction port by a distance of at least ¼ or more of a maximum length of diagonal lines of the fuel tank having a rectangular cross section. Portable fuel cell. 6. The fuel cartridge according to claim 1, wherein at least two types of fuels having different concentrations are stored in the fuel cartridge, and the supply unit supplies the fuel of each concentration individually from the fuel cartridge to the fuel tank. 2. A portable fuel cell according to item 1. The portable fuel cell according to claim 1, wherein the concentration sensor detects a change in density of fuel or a change in specific gravity of fuel. The portable fuel cell according to claim 1, wherein the concentration sensor detects a change in sound velocity propagating in the fuel. A portable fuel cell control method according to any one of claims 1 to 8,
When the output value of the concentration sensor continuously indicates a value of 100% or more, the control unit determines that there is no fuel in the fuel cell stack, and defines fuel from the fuel cartridge to the fuel tank. A control method for a portable fuel cell, wherein the supply means is controlled so as to supply only an amount of. When the output value of the concentration sensor vibrates between a value having a concentration of 100% or more and a value having a concentration of less than 100%, the control unit determines the amount of fuel in the fuel cell stack according to the oscillation period of the output value. Based on the estimated amount of fuel and the output value of the concentration sensor less than 100%, the supply means is controlled to supply a predetermined amount of fuel from the fuel cartridge to the fuel tank. The method for controlling a portable fuel cell according to claim 9. When the fuel cartridge stores at least two types of fuels having different concentrations, and the output value of the concentration sensor continuously indicates a value of 100% or more, the control unit is connected to the fuel cell stack. 11. The portable device according to claim 9, wherein the portable device determines that there is no fuel and controls the supply means to supply the fuel of each concentration from the fuel cartridge to the fuel tank in a specified concentration and a specified amount. Type fuel cell control method.

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