JP2006004785A - Liquid transportation method, liquid blending method, liquid transportation device, liquid blending device, and fuel cell device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid transportation method and a device, wherein two kinds or more of liquids can be transported stably at a prescribed ratio, and a liquid blending method and a device by utilizing this wherein two kinds or more of liquids can be blended stably at a prescribed ratio, and furthermore provide a small-sized fuel cell which is superior in power generation performance and efficiency. <P>SOLUTION: These are the liquid transportation method and the device, wherein one or two or more micro-pumps P1 to P11 are installed corresponding to respective kinds of liquids of two kinds or more, and a plurality of numbers of pumps P2 to P11 are installed as for at least one kind of the liquid, every pump is made to have the same performance, and it is driven as for the liquid for which one pump P1 is installed, while as for the liquid for which two or more pumps P2 to P11 are installed, the numbers of the pumps to be driven are decided out of these pumps in accordance with the prescribed ratio of liquid transportation, and by driving these pumps, two kinds or more of liquids are transported at the prescribed ratio of liquid transportation. These are the liquid blending method and the device 100, as well as the fuel cell device C1 utilizing these. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid feeding method and a liquid feeding device for feeding two or more kinds of liquids at a predetermined liquid feeding ratio, and further, the liquid feeding method, a liquid mixing method using the liquid feeding device, a liquid mixing device, and a fuel cell. Relates to the device.

  In recent years, μ-TAS (μ-Total Analysis System), which applies micromachine technology and refines apparatuses and methods for chemical analysis and synthesis to perform the analysis and synthesis, has attracted attention. The micro-TAS miniaturized in comparison with the conventional analysis and synthesis apparatus has advantages such as a small amount of sample, a short reaction time, and a small amount of waste. When employed in the medical field, the burden on the patient can be reduced by reducing the amount of the specimen (blood), and the cost of the test can be reduced by reducing the amount of the reagent. Furthermore, since the amount of the specimen and the reagent is small, the reaction time is greatly shortened, and the efficiency of the test can be improved. μ-TAS is also excellent in portability and is expected to be applied in a wide range of fields such as medical examination and environmental analysis.

  In such μ-TAS, a microfluidic system may be employed. In chemical analysis and environmental measurement using a microfluidic system, liquid feeding means such as a micro pump and a syringe pump are required to perform liquid feeding, liquid mixing, and detection on a device (chip) that performs analysis and measurement. Is done. However, for example, when the chip and the liquid feeding means are separated from each other, it is necessary to connect the two with a certain interface, but there arises a problem that bubbles are mixed at the time of the connection. In addition, the dead volume at the connecting portion becomes large, which makes it difficult to perform precise liquid feeding control, and requires useless samples and reagents. Furthermore, when an external liquid feeding means such as a syringe pump is connected, the entire apparatus including the chip becomes large, and the advantages of the microfluidic system cannot be utilized.

  In this regard, for example, Japanese Patent Laid-Open No. 2001-322099 discloses a piezoelectric element-driven micropump that can be mounted on a device (chip) that performs analysis, measurement, inspection, and the like, and that can be formed thin and not bulky. JP-A-2002-214241 discloses a reaction between a liquid to be inspected and a reagent equipped with a liquid supply mechanism that can be formed in a compact and not bulky thin shape using such a micropump and a liquid mixing mechanism using the liquid supply mechanism. A microchip for detection is disclosed. Further, Japanese Patent Application Laid-Open No. 2003-220322 discloses an improved liquid diffusing and mixing mechanism that uses such a micropump and that can be formed into a thin, compact and non-bulk shape.

By the way, fields in which a plurality of types of liquid feeding, mixing, and the like are required are not limited to the fields of analysis, measurement, and inspection.
With the start of the ubiquitous society, demands for long battery life are increasing. Conventional lithium batteries are approaching their theoretical limits and no further significant performance improvement can be expected. In the meantime, a fuel cell that can greatly extend the life of a conventional battery is attracting attention because of its high energy density per weight (volume).

  Among fuel cells in particular, (1) simple structure, (2) easy to obtain fuel without the need for large-scale infrastructure, (3) low cost, low temperature operation possible, for example, portable devices Direct methanol fuel cells (DMFCs), which can be said to be suitable as fuel cells for notebook personal computers, mobile phones, etc., have attracted attention and are actively studied.

  Fuel cell devices employing DMFC type fuel cells are classified into two types according to the fuel supply method. One is called an active type, which is a type that supplies fuel to the battery by a pump, and the other is a type that is called a passive type, which supplies fuel by capillary force or the like without using a pump. .

Here, the reaction formula of DMFC is shown.
Reaction on the fuel electrode side: CH ₃ OH + H ₂ O → CO ₂ + 6e ⁻ + 6H ⁺
Reaction on the air electrode side: (3/2) O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O
Total reaction: CH ₃ OH + (3/2) O ₂ → CO ₂ + 2H ₂ O

According to this reaction formula, methanol and water react in equimolar amounts to produce CO ₂ and two molecules of H ₂ O. However, an aqueous methanol solution having a low concentration of 3 to 5% is usually used as the fuel actually supplied to the fuel electrode. The reason is to prevent the phenomenon of crossover, in which methanol passes through the electrolyte membrane without reaching the above reaction at the fuel electrode and reaches the air electrode. The crossover phenomenon is more likely to occur as the methanol concentration in the fuel increases. When such a close-over phenomenon occurs, the reaction of methanol that should occur at the fuel electrode of the two DMFC poles (fuel electrode and air electrode) also occurs at the air electrode, resulting in waste of fuel and a decrease in potential on the air electrode side. A significant reduction in efficiency occurs. Accordingly, the above-mentioned low concentration aqueous methanol solution is usually used.

  In this way, the DMFC supplies a low-concentration methanol aqueous solution to the fuel electrode. In the active fuel cell device, the water generated on the air electrode side is recovered and the high-concentration methanol aqueous solution is diluted with this generated water. It is possible to construct a fuel dilution circulation system that supplies the fuel electrode while (one kind of mixing).

  According to the inventor's idea, the power generation system of FIG. 12 can be shown as an example. In the system shown in FIG. 12, a load L to be energized is connected to a fuel cell (DMFC) C, and a fuel tank t1, a recovery tank t2, and a mixer (mixing tank) MX are provided outside the cell. These are connected to the fuel cell C by piping. Water generated on the air electrode side of the fuel cell C is recovered to the recovery tank t2 by the pump PM3. In power generation, a high-concentration methanol aqueous solution is supplied from the fuel tank t1 with the pump PM1, and a dilution liquid is supplied from the recovery tank t2 with the pump PM2 to the mixer MX, and mixed there to dilute the high-concentration methanol aqueous solution. Meanwhile, the diluted aqueous methanol solution is supplied to the fuel electrode of the battery. An excess of the fuel supplied to the fuel electrode is recovered to the recovery tank t2.

  In order to optimize the methanol concentration in the fuel supplied to the fuel electrode, the methanol concentration of the fuel traveling from the mixer MX to the battery is detected by the concentration detection sensor DS, and the controller CONT determines whether the pumps PM1 and PM2 By controlling the operation, it is possible to adjust the ratio between the amount of the high-concentration methanol aqueous solution supplied to the mixer and the amount of the dilution liquid.

  According to this system, it is possible to increase the methanol concentration in the fuel tank. For example, if a 60 wt% aqueous methanol solution is used, it is approximately 1/20 to 1/12 as compared with the case where a 3 wt% to 5 wt% aqueous methanol solution is used from the beginning. The fuel tank can be made smaller.

  In addition, for example, in Japanese Patent Application Laid-Open No. 2003-132924, a high-concentration methanol aqueous solution is supplied from a methanol tank to a dilution tank by operating a valve attached to the tank, while being generated at the air electrode of the fuel cell main body. In this dilution tank, the aqueous methanol solution from the methanol tank is diluted with the recovered water, and the diluted aqueous methanol solution is supplied to the fuel electrode of the battery.

  Furthermore, by detecting the methanol concentration of the aqueous methanol solution in the dilution tank, and adjusting the amount of high-concentration aqueous methanol solution supplied from the methanol tank to the dilution tank by adjusting the opening amount of the valve based on the detection result, Controlling the methanol concentration of the aqueous methanol solution supplied to the fuel electrode is also disclosed.

Japanese Patent Application Laid-Open No. 2003-346846 discloses that an aqueous methanol solution from a methanol tank and an unused methanol solution and a by-product from the battery main body are introduced into a mixing chamber provided outside the battery main body, and the mixing chamber. It is disclosed that a circuit for introducing fuel to the battery is provided, and the fuel is circulated through the circuit by increasing or decreasing the volume of the fuel introduction chamber of the battery body or the liquid passage leading to the fuel by a piezoelectric actuator provided for them. Yes. Also in this fuel cell device, it is possible to store a high-concentration aqueous methanol solution in a methanol tank, dilute it with water recovered from the cell body to the mixing chamber, and use the diluted aqueous methanol solution as fuel. it is conceivable that.
Thus, even in a fuel cell device employing a DMFC type fuel cell, two types of liquids (methanol-containing liquid and dilution liquid) are required to be fed and mixed and diluted.

JP 2001-322099 A Japanese Patent Laid-Open No. 2002-214241 JP 2003-220322 A JP 2003-132924 A Japanese Patent Application Laid-Open No. 2003-346846

  However, in the liquid feeding mechanism and the liquid mixing mechanism disclosed in Japanese Patent Laid-Open No. 2002-214241 and Japanese Patent Laid-Open No. 2003-220322 using the micropump described in Japanese Patent Laid-Open No. 2001-322099, For example, when two kinds of liquids are sent at a ratio of 1: 1 or a ratio close to that, or mixed, there is substantially no problem, but at a ratio far away from 1: 1, for example, a ratio of 1:10. In the case of liquid and mixing, the two liquids are accurately fed at a ratio of 1:10, and the driving waveform applied to the driving piezoelectric element of the micropump for mixing and the driving method of the piezoelectric element are described. It is necessary to devise.

In addition, if the flow rate does not become 1:10 even if the drive waveform is changed, it is necessary to design each pump so that the pump performance itself becomes 1:10. In some cases, the rate of change in the characteristics of individual pumps varies depending on the influence of disturbance (for example, changes in the state of liquid (resistance, etc.) on the downstream side, and the ratio of liquid mixing (including mixed dilution) is stable. Disappear.
Such a problem occurs not only when the micropump disclosed in Japanese Patent Application Laid-Open No. 2001-322099 is employed, but also with respect to a liquid feed mechanism and a liquid mixing mechanism using a micropump that can be generally used in a microfluidic system. is there.

  Further, regarding the mixed dilution of the methanol aqueous solution and the diluent in the fuel cell, the active fuel cell device as illustrated in FIG. 12 has three pumps for supplying fuel, diluting solution, collecting liquid, in addition to the battery body. Furthermore, a mixing mechanism (mixer) for the high-concentration aqueous methanol solution and the recovered liquid is required, and the apparatus becomes large and complicated. For example, it is not suitable for a battery device for portable devices.

  In order to suppress the increase in the size of the fuel cell device, a high-concentration methanol aqueous solution dilution type device that employs a passive DMFC that does not require a pump is conceivable. However, active control of the flow rate of each liquid can be performed. There are no difficulties.

  The fuel cell devices disclosed in Japanese Patent Application Laid-Open Nos. 2003-132924 and 2003-34684 require a mixing mechanism (mixing tank) of a high-concentration aqueous methanol solution and water in addition to the battery main body, and the device is as much as that. Increases in size.

  As described above, with respect to the fuel cell device, a direct methanol type fuel cell is adopted, and the fuel cell device of the type in which the methanol aqueous solution is diluted with a diluent containing water and the diluted methanol aqueous solution is supplied to the fuel electrode of the cell. Although the problem has been pointed out, generally speaking, a fuel cell in which liquid fuel is used as a fuel is employed, and the liquid fuel is diluted with a diluting liquid and the diluted liquid fuel is supplied to the cell. In the type of fuel cell device, a mixing mechanism (for example, a mixing tank) for mixing the liquid fuel and the diluting liquid is required outside the battery body, and the fuel cell device is disadvantageously enlarged due to the mixing mechanism. It was.

Accordingly, the present invention provides a liquid feeding method and apparatus for sending two or more kinds of liquids at a predetermined ratio by a micropump, and a liquid feeding method capable of stably feeding the two or more kinds of liquids at a predetermined ratio. It is an object to provide an apparatus.
It is another object of the present invention to provide such a liquid feeding device, which can be formed compactly and compactly.

The present invention is also a liquid mixing method and apparatus for sending and mixing two or more liquids at a predetermined ratio by a micropump, and can stably mix the two or more liquids at a predetermined ratio. It is an object to provide a liquid mixing method and apparatus.
Another object of the present invention is to provide a liquid mixing apparatus which can be formed compactly and compactly.

  Furthermore, the present invention employs a fuel cell in which a liquid fuel is used as a fuel, dilutes the liquid fuel with a diluting liquid, and supplies the diluted liquid fuel to the fuel cell. It is an object of the present invention to provide a fuel cell device that can perform dilution with a diluting liquid stably and accurately, has good power generation performance and efficiency, and can be formed compactly and compactly.

(1) Liquid-feeding method and liquid-feeding apparatus The liquid-feeding method and apparatus of the present invention for solving the above-mentioned problems are as follows.
<Liquid feeding method>
A liquid feeding method for feeding two or more liquids at a predetermined liquid feeding rate.
One or two or more liquid feeding micropumps are provided for each of the two or more liquids, and a plurality of liquid feeding micropumps are provided for at least one of the two or more liquids. Provided, and all the micropumps for liquid delivery have the same performance,
For a liquid provided with one micropump, the one micropump is operated, and for each liquid provided with two or more micropumps, the liquid supply ratio is selected from the two or more micropumps. A liquid feeding method in which the number of micropumps to be operated is determined and the number of micropumps is operated to send the two or more liquids at a predetermined liquid feeding ratio.

<Liquid feeding device>
A liquid feeding device for feeding two or more kinds of liquids at a predetermined liquid feeding rate,
One or two or more liquid-feeding micropumps are provided for each of the two or more liquids, and at least one of the two or more liquids is used for feeding a plurality of liquids. A liquid-feeding device provided with a micropump, and any liquid-feeding micropump is a pump having the same performance.

  According to this liquid delivery device, for a liquid provided with one micropump, the one micropump is operated, and for each liquid provided with two or more micropumps, the liquid is provided from the two or more micropumps. By determining the number of micropumps to be operated according to the liquid feeding ratio and operating the number of micropumps, the two or more kinds of liquids can be fed at a predetermined liquid feeding ratio.

(2) Liquid mixing method and liquid mixing apparatus The liquid mixing method and apparatus according to the present invention for solving the above-described problems are as follows.
<Liquid mixing method>
It is a liquid mixing method in which two or more kinds of liquids are sent and mixed at a predetermined feeding rate,
One or two or more liquid feeding micropumps are provided for each of the two or more liquids, and a plurality of liquid feeding micropumps are provided for at least one of the two or more liquids. And providing a common mixing channel that communicates with each of the two or more liquid pumps provided for each of the two or more liquids, and each of the liquid pumps has the same performance,
For a liquid provided with one micropump, the one micropump is operated, and for each liquid provided with two or more micropumps, the liquid supply ratio is selected from the two or more micropumps. By determining the number of micropumps to be operated and operating the number of micropumps, the two or more kinds of liquids are sent to the mixing flow path at a predetermined liquid feeding ratio and mixed (including dilution by mixing). Liquid mixing method.

<Liquid mixing device>
A liquid mixing device that sends and mixes two or more liquids at a predetermined liquid feeding ratio,
One or two or more liquid-feeding micropumps are provided for each of the two or more liquids, and at least one of the two or more liquids is used for feeding a plurality of liquids. A micro-pump is provided, and a common mixing channel is provided to communicate with each of the liquid-feeding micropumps provided for each of the two or more kinds of liquids. A liquid mixing device that has the same performance as the pump.

  According to this liquid mixing apparatus, the one micropump is operated for the liquid provided with one micropump and the liquid provided with two or more micropumps is selected from the two or more micropumps. The number of micropumps to be operated is determined according to the liquid feed ratio, and the number of micropumps is operated to send the two or more liquids to the mixing channel at a predetermined liquid feed ratio for mixing and mixing. (Including dilution by mixing).

  In the liquid feeding method and apparatus and the liquid mixing method and apparatus according to the present invention, a plurality of micropumps may be employed for each of two or more kinds of liquids to be handled. In that case, for each liquid, the two or more liquids are fed at a predetermined ratio by operating all or a part of the plurality of micropumps for the liquid according to a predetermined liquid feeding ratio or mixing ratio. Or send and mix.

  According to the liquid feeding method and apparatus and the liquid mixing method and apparatus according to the present invention, the plurality of micropumps for liquid feeding have the same performance (for example, the same structure and the same size) with no variation in pump performance between pumps. Therefore, by adjusting the number of pumps to be operated, it is possible to easily adjust the liquid feed ratio of two or more liquids that are liquid feed targets or liquid feed mixing targets. The two or more kinds of liquids can be stably fed or mixed at a predetermined ratio. For example, even if there is a change in the state of the liquid on the downstream side of the pump (for example, a change in resistance to the flow, for example, a change in resistance caused by mixing or temperature fluctuations due to changes in the viscosity of the liquid). Thus, liquid feeding or liquid feeding mixing can be performed stably at a predetermined liquid feeding rate.

Further, it is possible to easily change the liquid feeding ratio or the liquid feeding mixing ratio by changing the number of micro pumps to be operated.
Furthermore, although a plurality of micropumps are employed as a whole, the pumps have the same performance, and therefore the pump drive circuit can be simplified.

In the liquid feeding device and the liquid mixing device according to the present invention, since the micropump is used as the liquid feeding pump, it is possible to reduce the size and size of the device accordingly.
As typical examples of such a micropump, a first throttle channel for sucking liquid, a second throttle channel for discharging liquid, a pump chamber between the first and second throttle channels, and the pump chamber A piezoelectric element installed on the flexible wall of the pump, and the pump chamber is vibrated by the piezoelectric element to contract and expand the pump chamber to suck liquid from the first throttle channel into the pump chamber. A pump that discharges liquid in the pump chamber from the second throttle channel can be mentioned.

  This type of micropump employs a piezoelectric element as an actuator, and the liquid flow path is formed by, for example, forming a groove or a recess by etching the film or plate-like body. 2 film and plate can be bonded together, so that it can be made compact and thin and small as a whole, and the liquid feeding device and liquid mixing device can be made compact, thin and small. To.

In any case, the driving of the micropump using the piezoelectric element may be performed by using a pump driving unit that applies an alternating voltage to the piezoelectric element, but if a frequency of 20 kHz or more is adopted as the frequency of the alternating voltage, The pump driving sound cannot be heard by humans, and the liquid feeding device and the liquid mixing device can be operated without discomfort due to noise.
In any case, in the liquid mixing method and apparatus according to the present invention, the mixing channel may be a meandering channel in order to ensure predetermined mixing of the liquid to be mixed, and the mixing ability may be improved.

(3) Liquid fuel apparatus The liquid fuel apparatus which solves the said subject is as follows.
A fuel cell in which liquid fuel is used as a fuel is employed, and the liquid fuel and dilution liquid are supplied at a predetermined liquid feed ratio and mixed to dilute the liquid fuel, and the diluted liquid fuel is supplied to the fuel cell. A fuel cell device to be supplied, wherein a first pump unit is stacked on the fuel cell, and the first pump unit includes one or two or more liquid feeding micros for each of the liquid fuel and the diluting liquid. A pump, and at least one of the liquid fuel and the diluting liquid has a plurality of liquid-feeding micropumps, and each of the liquid fuel and the diluting liquid. Each of the liquid-feeding micropumps provided in common, and supplying a diluted liquid fuel to the fuel cell from the mixed flow-path. Same pump The fuel cell system is a pump.

  According to this fuel cell apparatus, the one micropump in the first pump unit is operated for the one micropump, and the liquid having two or more micropumps is operated for the two or more micropumps. By deciding the number of micropumps to be operated and operating the number of micropumps, the liquid fuel and the diluting liquid are sent to the mixing channel at a predetermined liquid feeding rate to be mixed and mixed to be diluted. Liquid fuel can be obtained and supplied to the fuel cell to generate electricity.

  Also in this fuel cell device, a plurality of micropumps may be employed for each of the liquid fuel and the dilution liquid. In that case, for each liquid, the two or more liquids are sent at a predetermined ratio by operating all or part of the plurality of micropumps for the liquid according to a predetermined liquid-feeding mixture dilution ratio. It will be mixed and diluted.

  According to the fuel cell device of the present invention, the plurality of micropumps for liquid feeding in the first micropump unit have the same performance (for example, the same structure and the same size) with no variation in pump performance among the pumps. Therefore, the liquid fuel and dilution liquid feed ratio can be easily adjusted by selecting the number of pumps to be operated, so that both liquids can be stably and accurately delivered to a predetermined level. The liquid fuel can be fed and mixed at a liquid ratio to dilute the liquid fuel to a predetermined concentration, and the power generation performance and efficiency can be improved accordingly.

  Further, in the fuel cell device according to the present invention, a first micro pump unit that is a pump unit that employs a micro pump as a liquid feed pump and that can be used to dilute a liquid fuel with a diluting liquid and supply the fuel cell to the fuel cell. Are integrated. Therefore, it is not necessary to provide a mixing mechanism for mixing the liquid fuel and the diluting liquid outside the fuel cell, and piping for connecting the fuel cell and the mixing mechanism is not required. Therefore, the entire fuel cell device can be made compact and small, and can be used as a power source for portable devices, for example.

The mixing flow path in the first pump unit may meander for sufficient mixing of the liquid fuel and the diluting liquid.
In the fuel cell device, the second pump unit may be stacked on the surface opposite to the surface where the first pump unit of the fuel cell is stacked. In this case, the second pump unit collects at least a liquid generated by an electrochemical reaction in the fuel cell. When there is a liquid that passes through the electrolyte layer from the fuel electrode side of the fuel cell and exits to the air electrode side, the liquid may be recovered.
Since the second pump unit is also laminated on the fuel cell and integrated with the fuel cell, even if the second pump unit is provided, it does not hinder downsizing of the fuel cell device.

  If possible, a liquid generated by an electrochemical reaction in the fuel cell or a liquid that passes through the electrolyte layer from the fuel electrode side of the fuel cell and exits to the air electrode side may be used as the dilution liquid. Good. In this case, the second pump unit uses the collected liquid as a dilution liquid to the first pump unit via the dilution liquid circulation path formed in the stacked body of the fuel cell, the first pump unit, and the second pump unit. It may be supplied.

Alternatively, the second pump unit may send the recovered liquid as a dilution liquid to the recovery container, and supply the dilution liquid from the recovery container to the first pump unit.
In the case where a recovery container is provided, the first pump unit may send excess diluted liquid fuel to the recovery container.

  In addition, about the liquid fuel before dilution, a liquid fuel storage container may be provided and liquid fuel may be supplied from the container to the first pump unit. As a typical example of such a liquid fuel container, a replaceable container, for example, a cartridge type container can be cited.

In order to simplify the arrangement of the liquid passage as much as possible and achieve further miniaturization of the fuel cell device, the first pump unit is preferably stacked on the fuel cell adjacent to the fuel electrode. In this case, when the second pump unit is also provided, the second pump unit may be stacked on the fuel cell adjacent to the air electrode.
Depending on the structure of the fuel cell and the like, an electrode film electrically connected to the fuel electrode may be formed on the surface of the first pump unit facing the fuel electrode, if necessary. Also in the second pump unit, an electrode film electrically connected to the air electrode may be formed on the surface facing the air electrode.

  In any case, in order to further reduce the size of the fuel cell device, both the fuel cell and the first pump unit may be formed in a flat shape when the second pump unit is provided. preferable. As a result, the fuel cell device according to the present invention can be formed to be approximately the same size as the passive device while being an active device.

  In any case, when the first pump unit is stacked adjacent to the fuel electrode of the fuel cell, the following can be given as typical examples of the first pump unit. In other words, a diluted liquid fuel passage for supplying the diluted liquid fuel to the fuel electrode is provided on a surface facing the fuel electrode, and the liquid fuel is supplied to a portion opposite to the surface facing the fuel electrode. The liquid fuel supply path including the liquid feed micropump, the dilution liquid supply path including the liquid feed micropump for supplying the dilution liquid, and both the liquid fuel supply path and the dilution liquid supply path communicate with each other. The pump unit having the mixing flow path communicating with the diluted liquid fuel path. Furthermore, a gas vent hole for discharging the gas generated at the fuel electrode through the diluted liquid fuel passage may be provided.

This first pump unit has a diluted liquid fuel passage for supplying the diluted liquid fuel to the fuel electrode on the surface facing the fuel electrode, so that it serves as a separator on the fuel electrode side in the conventional fuel cell device. Also works.
A conductive film may be formed on the surface facing the fuel electrode having the diluted liquid fuel passage, and the film may be used as an electrode.
As will be described later, the first pump unit can be formed flat and thin.

  When the second pump unit is stacked adjacent to the air electrode of the fuel cell, the following can be given as representative examples of the second pump unit. That is, a liquid passage to be collected is provided on the surface facing the air electrode, and a liquid collection path including a liquid collection micropump for collecting the liquid is provided on the opposite side of the surface facing the air electrode. And a pump unit having a passage leading from the liquid passage facing the air electrode to the liquid recovery passage. Furthermore, you may have an air intake hole for supplying air from the exterior via this liquid channel | path to an air electrode.

Since the second pump unit has a liquid passage on the surface facing the air electrode, the second pump unit also functions as a separator on the air electrode side in the conventional fuel cell device.
A conductive film may be formed on the surface facing the air electrode having such a liquid passage, and the film may be used as an electrode.
This second pump unit can also be formed flat and thin as will be described later.

  In any case, also in the fuel cell device according to the present invention, each of the micropumps typically includes a first throttle channel for sucking a liquid, a second throttle channel for discharging a liquid, A pump chamber between the first and second throttle channels, and a piezoelectric element installed on a flexible wall of the pump chamber that can function as a diaphragm, and vibrates the pump chamber wall with the piezoelectric element Thus, a pump that contracts and expands the pump chamber to suck liquid from the first throttle channel into the pump chamber and discharge the pump chamber liquid from the second throttle channel can be used.

  Such a micropump using a piezoelectric element may be driven by using a pump drive unit that applies an alternating voltage to the piezoelectric element. If a frequency of 20 kHz or more is adopted as the frequency of the alternating voltage, the pump driving sound is human. Therefore, even if the fuel cell device is mounted on a mobile phone or the like, the user will not feel uncomfortable.

  As a typical example of the fuel cell, as described above, (1) the structure is simple, (2) fuel is easily available without requiring large-scale infrastructure development, and (3) operation at low cost and low temperature is possible. From such points, for example, a direct methanol fuel cell (DMFC) that can be said to be suitable as a fuel cell for portable devices (notebook personal computers, mobile phones, etc.) can be mentioned.

When such DMFC is employed, the liquid fuel is a methanol-containing liquid fuel (for example, a highly concentrated aqueous methanol solution), and the dilution liquid is a liquid containing water. The water generated at the air electrode of the DMFC or the moving liquid from the fuel electrode side can be used as a dilution liquid.
In addition, when such a DMFC is employed, it is preferable that the DMFC has a so-called membrane electrode assembly (MEA) structure that can be thinned into a flat shape in order to reduce the size of the fuel cell device. . The MEA is a fuel cell having a structure in which an electrolyte membrane is sandwiched between a fuel electrode and an air electrode.

As described above, according to the present invention, there is provided a liquid feeding method and apparatus for sending two or more kinds of liquids at a predetermined ratio by a micropump, which can stably send the two or more kinds of liquids at a predetermined ratio. The liquid feeding method and apparatus which can be provided can be provided.
Moreover, it is this liquid feeding apparatus, Comprising: The liquid feeding apparatus which can be formed compactly and compactly can be provided.

Further, according to the present invention, there is provided a liquid mixing method and apparatus for sending and mixing two or more liquids at a predetermined ratio by a micropump, wherein the two or more liquids can be stably mixed at a predetermined ratio. A liquid mixing method and apparatus that can be provided can be provided.
Moreover, it is this liquid mixing apparatus, Comprising: The liquid mixing apparatus which can be formed compactly and compactly can be provided.

  Furthermore, according to the present invention, there is provided a fuel cell device in which a liquid fuel is used as a fuel, the liquid fuel is diluted with a diluting liquid, and the diluted liquid fuel is supplied to the fuel cell. It is possible to provide a fuel cell device that can stably and accurately dilute a fuel with a diluting liquid, has good power generation performance and efficiency, and can be formed compactly and compactly.

Embodiments of the present invention will be described below.
FIG. 1 shows an example of a liquid mixing apparatus using an example of a liquid feeding apparatus capable of performing the liquid feeding method according to the present invention. The liquid mixing apparatus can implement the liquid mixing method according to the present invention.
The liquid mixing apparatus 100 shown in FIG. 1 includes a plurality of micropumps P1, P2 to P6, and P7 to P11. Each pump is the pump of the same performance which shows the same structure, the same size, and the same operation | movement which are explained in full detail later with reference to FIG.

  A supply port 11 for the first liquid is provided for the pump P 1, and the supply port 11 communicates with the liquid suction side of the pump P 1 via a flow path 12. A flow path 13 communicates with the liquid discharge side of the pump P1.

  A second liquid supply port 14 is provided for the pumps P2 to P6 and P7 to P11. The supply port 14 communicates with the respective liquid suction sides of the pumps P2 to P6 via the flow path 15 and the flow path 151 branched from the flow path 15, and the flow path 161 branched from the flow path 16 and the flow path 16 Are communicated with each liquid suction side of the pumps P7 to P11.

  A flow path 171 communicates with each liquid discharge side of the pumps P <b> 2 to P <b> 6, and these flow paths 171 merge with the flow path 17. A flow path 181 communicates with the liquid discharge side of each of the pumps P <b> 7 to P <b> 11, and these flow paths 181 merge with the flow path 18.

  The flow path 13 communicating with the pump P1, the flow path 17 communicating with the pumps P2 to P6, and the flow path 18 communicating with the pumps P7 to P11 merge at the junction 19 and continue to the mixing flow path 20. ing. A discharge port 21 is provided at the end of the mixing channel 20. The discharge port 21 discharges a mixed liquid in which the first liquid and the second liquid are mixed.

A portion of the flow paths 13, 17, and 18 upstream from the merging portion 19 is a portion constituting a liquid feeding device, and the liquid mixing device 100 is formed by connecting the mixing flow channel 20 to the portion.
Details of each pump will be described later.

  According to this liquid mixing apparatus 100, the first liquid can be supplied from the supply port 11 and can be fed from the flow path 13 toward the mixing flow path 20 by operating the micro pump P1. The second liquid is supplied from the supply port 14, and the number of pumps selected from the ten micro pumps P2 to P11 for the second liquid are operated to mix the flow from the flow path 17 and / or the flow path 18. The liquid can be sent to the path 20.

  At this time, each pump is a pump having the same performance, and since the pumping amount of each pump is the same, if any one of the pumps P2 to P11 is operated while the pump 1 is operated. The liquid feeding and mixing ratio of the first liquid and the second liquid is 1: 1. If, for example, four pumps P2 to P11 are operated, the liquid feeding and mixing ratio of the first liquid and the second liquid is 1: 4.

  Thus, according to this liquid mixing apparatus 100, since the same performance with no variation in pump performance between pumps is adopted as a plurality of micro pumps for liquid feeding, the pump P1 is operated and the pump P2 The number of pumps to be operated from among P11 is selected and determined according to the predetermined liquid feeding and mixing ratio of the first and second liquids, and the predetermined number of pumps are operated stably. The liquid can be fed at a ratio, mixed in the mixing channel 20, and more specifically, mixed by using diffusion mixing in the width direction of the mixing channel and discharged from the discharge port 21. For example, even if there is a change in the state of the liquid on the downstream side of the pump (for example, a change in resistance to the flow, such as a change in resistance caused by mixing or temperature fluctuations due to fluctuations in liquid viscosity), Both liquids can be stably fed and mixed at a predetermined ratio. Here, “mixing” of the liquid includes dilution by mixing.

  Moreover, it is also possible to easily change the liquid feeding and mixing ratio by changing the number of pumps operated for the pumps P2 to P11. Furthermore, although a plurality of micropumps P1 to P11 are employed as a whole, since these pumps have the same performance, the pump drive circuit can be simplified.

  Each of the micro pumps P1 to P11 shows the structure and operation shown in FIG. That is, the first throttle channel f1 for sucking liquid, the second throttle channel f2 for discharging liquid, the pump chamber PC between the first and second throttle channels f1, f2, and the pump chamber PC This is a pump including a piezoelectric element PZT installed on a flexible wall (diaphragm) DF.

  The pump chamber PC is contracted and expanded by applying an alternating voltage to the piezoelectric element PZT to vibrate the pump chamber wall (diaphragm) DF, and the liquid is sucked into the pump chamber PC from the first throttle channel f1, and the second throttle. The pump chamber liquid can be discharged from the flow path f2.

  More specifically, the first and second throttle channels f1 and f2 have the same or substantially the same cross-sectional area, but the channel f2 is formed longer than the channel f1. As an alternating voltage for driving the piezoelectric element PZT, as shown in FIG. 9C, an alternating voltage showing a steep rise and a gradual fall is used.

  As shown in FIG. 9A, when the diaphragm DF is abruptly deformed by the piezoelectric element and the pump chamber PC is abruptly contracted at the steep rise of the applied voltage, the liquid is layered by the channel resistance in the long channel f2. On the other hand, the liquid flows turbulently in the short flow path f1, and the outflow of the liquid from the flow path f1 is suppressed. Thereby, the pump chamber liquid can be discharged from the flow path f2.

  As shown in FIG. 9B, when the diaphragm DF is gently returned by the piezoelectric element when the applied voltage gradually falls, and the pump chamber PC is gently expanded, the short passage f1 causes the inside of the pump chamber PC. While the liquid flows into the liquid, the liquid discharge from the long channel f2 having a larger channel resistance than the channel f1 is suppressed at this time. Thereby, the liquid can be sucked from the flow path f1 into the pump chamber PC.

  Therefore, liquid flow is possible in the desired direction by disposing the flow path f1 on the upstream side and the flow path f2 on the downstream side in the desired liquid supply direction. Each of the pumps P <b> 1 to P <b> 11 has such a structure and performs liquid feeding according to such an operation principle. In FIG. 1 etc., the piezoelectric elements of the pumps P1 to P11 are indicated by PZT.

  The micropump shown in FIG. 9 applies an alternating voltage that shows a gradual rise and a steep fall to the piezoelectric element PZT as shown in FIG. 9F, as shown in FIG. 9D. The pump chamber liquid can be discharged from the flow path f1 and the liquid can be sucked from the flow path f2 as shown in FIG. 9E. Here, the drive waveform of FIG. 9C is employed.

  Each pump in the apparatus 100 illustrated in FIG. 1 can be driven by applying an alternating voltage to a piezoelectric element of the pump from a pump driving unit (not shown). That is, when the first liquid and the second liquid are fed, mixed or diluted, the waveform shown in FIG. 2A as the voltage waveform applied to the piezoelectric element of the pump P1 is replaced with the piezoelectric elements of the pumps P2 to P11. The waveform shown in FIG. 2B is adopted as the waveform of the voltage to be applied, and this drive waveform is applied from the pump drive unit (not shown) to the pump piezoelectric element. The waveforms in FIGS. 2A and 2B are of the type shown in FIG. 9C and the same waveform. Thus, in the liquid mixing apparatus 100, since any micropump can be driven with the same drive waveform, the pump drive unit (not shown) can be simplified accordingly.

  The micropump described above employs a piezoelectric element for the actuator, and the liquid flow path is formed with a groove or a recess by, for example, etching of a film or a plate-like body, as will be described later. Since the second film or plate-like body can be bonded to the film or plate-like body on which the point is formed, it can be formed compactly, thinly and compactly, and the liquid mixing apparatus 100 can be made compact. Thinning and miniaturization are possible.

FIG. 3A shows a modification 100 ′ of the liquid mixing apparatus 100 described above. This apparatus 100 ′ is obtained by changing the mixing flow path 20 in the apparatus 100 into a meandering mixing flow path 200, and the other points are the same as the apparatus 100, and the same parts and portions as the apparatus 100 are denoted by the same reference numerals as in FIG. Is attached.
In the liquid mixing apparatus 100 ′, the mixing flow path 200 is long and meandering, so that the first and second liquids flowing into the mixing flow path 200 from the merging portion 19 can be sufficiently diffused and mixed.
FIG. 3B shows another modification 100 a of the liquid mixing apparatus 100. This apparatus 100a is provided with a plurality of pumps P1 ₁ , P1 ₂ , and P1 ₃ for the first liquid in the apparatus 100. Each of these pumps is a pump having the same performance as the pumps P2 to P11. In the apparatus 100a, for the first liquid, one or more of the plurality of pumps P1 ₁ , P1 ₂ , P1 ₃ are selectively operated according to the desired liquid feeding and mixing ratio of the first and second liquids. be able to.

  In order to be able to mix the first liquid and the second liquid even if the mixing channel is shortened as in the apparatus 100 of FIG. 1, the pump P1 for the first liquid is shown in FIG. While intermittently driving with the intermittent drive waveform, the number of pumps (pumps to be operated) selected from the pumps P2 to P11 are intermittently driven with the intermittent drive waveform shown in FIG. Is intermittently driven so that the operation stops during operation, thereby allowing the first liquid and the second liquid to alternately flow into the mixing flow path 20, thereby allowing the first and second liquids to flow into the mixing flow path 20. You may make it make it diffusively mix in. In this case, mixing of both liquids in the flow path 20 is mainly performed by diffusion of both liquids in the direction of the flow path, and the diffusion distance is shortened. Since the diffusion distance is shortened, the mixing channel 20 can be short.

  In this case, when the pump P1 is operating and the other pumps are stopped, the first liquid flows backward to the other pump side, or when the pump P1 is stopped and the other pumps are operating, the pump In order to prevent the second liquid from flowing back to the P1 side, the drive waveform shown in FIG. 5A for the pump P1, and the drive waveform shown in FIG. In the driving waveform 4, when the original driving waveform is not applied, the liquid may be operated with a driving waveform showing a voltage value much lower than the voltage value of the original driving waveform to prevent the back flow of the liquid.

  In the mixing apparatus 100 of FIG. 1, when the pump is driven by the driving waveform of FIG. 2 or the driving waveform of FIG. 4 or FIG. 5, if the liquid discharge amount from the mixed liquid discharge port 21 is increased, FIG. In the drive waveform of Fig. 4 and Fig. 5, the liquid flow velocity becomes faster, and in the drive waveforms of Fig. 4 and Fig. 5, the size (amount) per liquid mass intermittently sent to the mixing channel becomes too large. There is a risk of reaching the discharge port 21 before being mixed into the state.

  When there is such a fear when a mixed liquid or a mixed diluted liquid is desired at a certain flow rate, for example, as shown in FIG. 6, a liquid mixing apparatus 100 (liquid mixing block) of the type shown in FIG. A plurality of liquid mixing devices 100 ″ may be used. In the device 100 ″, a common flow channel 141 communicates with the flow channels 15 and 16 in each block 100, and the second liquid is connected to the end of the flow channel 141. Supply port 142 is provided.

  By adopting a plurality of blocks in the apparatus 100 ″, when the driving waveform of FIG. 2 is adopted, the liquid flow rate can be slowed down to obtain a desired amount of mixed liquid or mixed diluted liquid, as shown in FIGS. When the drive waveform is adopted, a desired amount of liquid mixture or liquid mixture can be obtained by reducing the size of each liquid mass intermittently fed into the mixing channel.

  Further, in the apparatus 100 ″, the amount of liquid delivered by each pump may be small, in other words, the individual pump can be reduced. Therefore, the optimum driving frequency of the pump is increased, for example, a driving frequency of 20 kHz or more. It is also possible to adopt the above, and at a driving frequency of 20 kHz or higher, it is not audible to the human ear, and there is no need to give a person a discomfort.

Next, an example of a fuel cell device using the liquid mixing device 100 ″ of FIG. 6 will be described with reference to FIGS.
7A is a plan view of the fuel cell device C1, FIG. 7B is a side view of the device, and FIG. 7C is a bottom view of the device.
8A is a cross-sectional view taken along line AA in FIG. 7B, FIG. 8B is a cross-sectional view taken along line BB in FIG. 7B, and FIG. 8C is FIG. ), And FIG. 8D is a sectional view taken along the line DD in FIG. 7B.

  The illustrated fuel cell device C1 is a device that uses a methanol-containing liquid (typically a high-concentration methanol aqueous solution diluted with a diluting solution and used as a diluted liquid fuel. 1 pump unit 1 and 2nd pump unit 2 are included.

  In this example, the fuel cell 3 is a direct methanol fuel cell (hereinafter also referred to as “DMFC”), and here, an MEA (a fuel electrode 32 and an air electrode 33 joined to both surfaces of the electrolyte membrane 31). Membrane Electrode Assembly) structure. MEA having various structures is known. In this example, the electrolyte membrane 31 is an electrolyte polymer membrane (for example, Nafion (perfluorosulfonic acid membrane) manufactured by DuPont), and the fuel electrode 32 is in contact with the electrolyte membrane 31. It consists of a catalyst layer (for example, platinum black or a platinum alloy supported on carbon black) and an electrode such as carbon paper laminated thereon, and the air electrode 33 is laminated on the same catalyst layer in contact with the electrolyte membrane 31. It consists of the same electrode.

Depending on the structure of the MEA, an electrode layer for extracting power may be provided on at least one of the first and second pump units 1 and 2.
Such an electrode layer can be formed of platinum or the like on the surface of the pump unit facing the fuel electrode or the air electrode by using various thin film forming methods such as a sputtering method. Alternatively, it may be adhered to the air electrode.

  The first pump unit 1 includes flat quadrangular members 11A and 12A. These members are laminated in a flat shape. As shown in FIGS. 7A and 8A, the member 11A has a groove-like liquid channel 12 for forming the liquid mixing device 100 ″ shown in FIG. 6 on the surface facing the member 12A. 13, 13, 16, 17, 18, 20, etc. (see also FIG. 1 and FIG. 6), and further flow channels communicating with the flow channels 15 and 16 of each block (liquid mixing device block) 100. 141, etc. The member 12A is laminated on the surface of the member 11A on the side where the flow path is formed, whereby the liquid mixing apparatus 100 ″ is formed.

  In this case, the flow paths 12 and 13 including the micro pump P1 of each block 100 in the liquid mixing apparatus 100 ″ are liquid fuel supply paths. A hole 11 penetrating the member 11A from the upstream end of the flow path 12 is formed. 6 corresponds to the first liquid supply port 11 in the liquid mixing apparatus of Fig. 6 and is used as the liquid fuel supply port 11. A liquid fuel storage container (not shown) is connected to the supply port 11, from which methanol is contained. Liquid is supplied.

  In addition, the other flow paths 15, 16, 17, 18 and the like including the micro pumps P2 to P11 of each block 100, and the flow path 141 are dilution liquid supply paths for supplying a dilution liquid (in this case, water). The channel 141 communicates with the recessed portion 142, which corresponds to the second liquid supply port 142 in the apparatus 100 ″ in FIG. 6 and is used as the dilution liquid supply port 142. Further, a groove-like flow path 143 is formed in communication, and a recess-shaped dilution liquid receiving portion 144 is formed at the end of the flow path 143.

  The flow path 20 of each block 100 is used as a mixing flow path 20 for mixing the liquid fuel and the dilution liquid. A member through hole 21 is formed at the end of the flow path 20, which corresponds to the mixed liquid discharge port 21 in the apparatus 100 ″ in FIG. 6 and is used as the diluted liquid fuel discharge port 21.

  As shown in FIG. 8B, the member 12A includes a plurality of dilute liquid fuels in a comb-like arrangement for supplying diluted liquid fuel to the fuel electrode on the surface of the battery 3 facing the fuel electrode 32. A common recess-like diluted liquid fuel passage 122 having a passage 121 and communicating with the plurality of passages 121 is provided. A through hole 123 is formed from the passage 122 to the member 11A side. The through hole 123 is provided at a position that matches the diluted liquid fuel discharge port 21 of the member 11 </ b> A, and the diluted liquid fuel flows into the passages 122 and 121 from this position and is supplied to the fuel electrode 32.

  In addition, a groove-like gas vent hole 124 is formed for communicating each passage 121 to the outside of the member. The gas vent hole 124 is used for releasing carbon dioxide gas generated on the fuel electrode side. Furthermore, a through hole 125 is formed at the end of the member 12A. The through hole 125 is provided at a position matching the dilution liquid receiving portion 144 in the member 11A. The battery 3 has a liquid passage 34 that matches the through hole 125 of the member 12A (see FIG. 7B).

  In addition to the above, the gas flow part GD is provided in the members 11A and 12A so that their positions coincide with each other. The gas circulation part GD is a part which has been subjected to water repellent treatment so as to form a plurality of fine gas circulation holes and prevent the passage of liquid. The gas circulation part GD may be provided corresponding to at least one, more preferably a plurality of, for example, the diluted liquid fuel passages 121 (see FIG. 8B). The gas circulation part GD in the first pump unit 1 is for gas release.

  The second pump unit 2 includes flat rectangular members 21A and 22A. These members are laminated in a flat shape. As shown in FIG. 8C, the member 21 </ b> A has a passage for a liquid (here, water) generated by an electrochemical reaction in the fuel cell 3 on the surface facing the air electrode 33 of the battery 3, that is, a comb shape. And a plurality of groove-like passages 211 arranged in a row, and a common recess-like passage 212 communicating with the passages. A through hole 213 is formed from the passage 212 to the member 22A side. In addition, a groove-like air intake hole 214 is formed to communicate each passage 211 with the outside of the member. A through hole 215 is formed at the end of the member 21 </ b> A, and the hole is located at a position matching the liquid passage 34 of the battery 3.

  As shown in FIGS. 7C and 8D, the member 22A has a groove-like liquid recovery path including a micropump PX having the same structure and operation as the pump P1 and the like on the surface facing the member 21A. 221. The liquid recovery path 221 recovers a liquid (here, water) generated by an electrochemical reaction in the fuel cell 3 or a liquid that may pass from the fuel electrode 32 side through the electrolyte membrane 31 to the air electrode 33 side. It is. A concave liquid receiving portion 222 is formed at the upstream end of the liquid recovery path 221 from the pump PX, and a concave liquid discharge portion 223 is formed at the downstream end of the pump P3. .

  The water generated on the air electrode 33 side of the battery or the moving liquid from the fuel electrode 32 side of the battery passes through the through holes 213 of the member 21A from the liquid passages 211 and 212 of the member 21A by the operation of the pump PX. It flows into the liquid receiving part 222, passes through the liquid recovery path 221 of the member 22A, the liquid discharge part 223, the through hole 215 of the member 21A, the liquid passage 34 of the battery, the through hole 125 of the member 12A in the first pump unit 1, and the member The liquid is supplied to the dilution liquid supply port 142 via the 11A liquid receiving portion 144 and the flow path 143. Thus, the dilution liquid can be supplied to the mixing channel 20 by operating at least one of the pumps P <b> 2 to P <b> 11 in the block 100 of the first pump unit 1.

  In addition to the above, as shown in FIGS. 8C and 8D, the members 21A and 22A are provided with gas circulation portions GD so that their positions coincide with each other. The gas circulation part GD is the same as that in the first pump unit 1 and may be provided corresponding to at least one, more preferably a plurality of, for example, the liquid passage 211 (see FIG. 8C). The gas circulation part GD here is used for taking in air from the outside.

According to the fuel cell device C1 described above, power can be generated as follows.
A methanol-containing liquid (for example, a high-concentration methanol aqueous solution) is supplied as liquid fuel from a liquid fuel container (not shown) to the first pump unit 1 and the pump P1 of each block 100 is driven by a pump drive unit (not shown) to mix the flow A methanol-containing liquid is supplied to the passage 20.

Further, in each block 100, the number of pumps selected from the pumps P <b> 2 to P <b> 11 are driven to supply the dilution liquid to the mixing channel 20. As a result, the diluted methanol-containing liquid diluted with the diluent from each block 100 is supplied to the fuel electrode 32 of the battery 3.
The number of pumps to be operated among the pumps P2 to P11 is determined so as to obtain a predetermined dilution ratio of the methanol-containing liquid, and thus a predetermined liquid feeding ratio of the methanol-containing liquid and the diluted liquid.

Thus, in the fuel cell 3,
Since a reaction of CH ₃ OH + (3/2) O ₂ → CO ₂ + 2H ₂ O occurs and power is generated, a load (not shown) connected to the battery 3 can be energized.

  At the beginning of use of the fuel cell device C1, the battery 3 is supplied with a liquid fuel (methanol-containing liquid) supplied from a liquid fuel storage container (not shown) and, for example, a dilution previously filled in the pumps P2 to P11. After that, water or the like generated on the air electrode 33 side by the electrochemical reaction of the battery 3 begins to be supplied to the first pump unit 1 by the second pump unit 2, and the first pump unit 1 The methanol-containing liquid supplied from 4 can be mixed and diluted with the diluting liquid supplied from the second pump unit 2 and supplied to the fuel cell 3 as a diluted liquid fuel. Thus, the raw fuel stored in the container 4 can be used for a long time. Power can be generated for hours. In addition, the filling of the dilution liquid into the pumps P2 to P11 is performed by providing a dilution liquid supply port (not shown) communicating with the dilution liquid flow path leading to the pumps P2 to P11. This can be done by supplying a diluent, and the supply port may be closed thereafter.

  According to the fuel cell device C1 described above, since the plurality of micropumps P1 to P11 for liquid feeding in the first micropump unit 1 have the same performance with no variation in pump performance between pumps. The liquid feed ratio of the dilution liquid can be easily adjusted by selecting the number of pumps to be operated, and both liquids can be fed and mixed at a predetermined liquid feed ratio stably and accurately, and the liquid fuel can be mixed at a predetermined concentration. The power generation performance and efficiency can be improved accordingly.

  For example, when a 60% aqueous methanol solution is used as the liquid fuel, the methanol concentration is increased by driving all 10 pumps P2 to P11 for diluting liquid to one pump P1 for the 60% aqueous methanol solution in each block 10. A diluted fuel of about 5 to 6% can be obtained.

  In addition, the methanol concentration in the fuel supplied to the fuel electrode 32 can be controlled by controlling the number of driving of the diluting liquid pumps, and accordingly, according to the operating load of the equipment connected to the fuel cell. Optimal fuel concentration control is also possible. In general, I would like to use fuel that is as concentrated as possible to improve battery characteristics. However, when the load on the battery is small, if the concentration is high, methanol that could not react on the anode side will move to the cathode side. Because of this phenomenon, the battery characteristics are degraded. Therefore, it is effective to increase the density when the load is large and decrease the density when the load is small.

  The fuel cell device C1 can be formed compactly and flatly and thinly, for example, in the form of a card, for example, as can be seen from a manufacturing method example such as a micropump described later. It is suitable as a power source for portable devices. If each pump is driven by applying an alternating voltage having a frequency of 20 kHz or more, even if it is mounted on a mobile phone, for example, the pump drive sound is not heard by humans and the phone user is not uncomfortable.

In the micropump unit 1 of the fuel cell device C1, the diluting liquid is initially branched and supplied from one supply port 142 through the flow path 141, but a supply port is provided for each block. Alternatively, the diluent may be circulated from the air electrode side.
Further, water or the like generated on the air electrode side may be collected in a collection container (not shown), and a diluent may be supplied from the collection container to each block 100. Further, an excess of the diluted liquid fuel supplied to the fuel electrode 32 may be recovered in the recovery container.

<Manufacture of liquid feeding device, liquid mixing device, micro pump unit>
Below, some examples of manufacture of the liquid feeding apparatus containing a micropump, a liquid mixing apparatus, and a micropump unit are given.
(1) In the case of comprising a Si substrate and a glass plate A channel groove is processed on the Si substrate by anisotropic etching, and a flat glass is anodically bonded to the Si substrate to form a liquid passage. The driving piezoelectric element is bonded to the diaphragm portion of the Si substrate.
According to this method, since the liquid passage can be formed of a material having a high Young's modulus, the pump performance is improved.
(2) When constituted by resin and glass plate A channel groove is formed by injection molding of resin, imprint or the like, and a thin glass plate is adhered to the resin plate with an adhesive to form a liquid passage. The driving piezoelectric element is attached to the diaphragm portion of the glass plate.
According to this method, the pump unit can be formed at low cost.
(3) In the case of being composed of glass The first glass plate in which the flow channel is formed by a method such as photolithographic processing of photosensitive glass, sand blasting of glass, glass molding, laser processing of a glass plate, etc. In addition, the second flat glass is directly bonded. Alternatively, a low melting point glass film is formed on both or one of the bonding surfaces of the first and second glasses by a sputtering method, a vapor deposition method or the like, and bonded by heating and pressing. Alternatively, a Si film is formed on one of the first and second glasses by a sputtering method or the like and anodic bonded. By any of these operations, a liquid flow path or the like is formed, and a piezoelectric element is attached to one of the diaphragm portions of both the bonded glasses with an adhesive or the like.
Also by this method, the pump unit can be formed at a low cost.
(4) In the case of being composed of ceramic, a channel groove is formed by a method such as green sheet molding, sand blasting, laser processing, etc., and the green sheet on which one or both are formed is positioned and bonded to the green sheet, Integration is performed by firing while applying pressure. Alternatively, similarly formed green sheets are fired to form a ceramic plate, and a low-melting glass film is formed on one side by sputtering, vapor deposition, or the like, and bonded by heating and pressing. Alternatively, anodic bonding is performed by forming glass on one of the similarly formed and fired ceramic plates and forming Si on the other. By any one of these operations, a liquid flow path or the like is formed, and the piezoelectric element is attached to one of the diaphragm portions of both ceramics joined with an adhesive or the like.
According to this method, since the liquid passage can be formed of a material having a high Young's modulus, the pump performance is improved.

In addition to the above, an electroformed product in which a groove through which liquid or gas can flow is formed, a molded product of carbon, a product obtained by etching a stainless steel plate, or the like can also be used.
In addition, even if it employ | adopts any manufacturing method of said (1)-(4), a vent hole and an air intake hole are simultaneously formed as needed. The gas circulation part DG may be formed at the same time if possible, or may be formed later.

  Next, a specific example of the manufacturing method of the liquid mixing apparatus will be described. In order to simplify the description and facilitate understanding, the microchip MT shown in FIG. 10 functioning as a liquid feeding apparatus and a liquid mixing apparatus will be described as an example. . 10A is a plan view of the microchip MT, FIG. 10B is a side view of the chip, and FIG. 10C is a cross-sectional view taken along the line XX of FIG. 10B.

  In the chip MT shown in FIG. 10, the first liquid pump and the second liquid pump are one each unlike the present invention, but the liquid feeding device, the liquid mixing device, and the micro pump unit according to the present invention are the number of pumps. Only the number and arrangement of the liquid flow paths are different from the chip MT, and it can be formed in a compact, flat, thin and small size in the same manner as the chip MT.

  The liquid mixing device MT of FIG. 10 is of a microchip type, and includes a first liquid supply path L1 including a micropump Pa and a second liquid supply path L2 including a micropump Pb, and the pump upstream of the supply path L1. A liquid supply port Li1 is provided at the side end, and a liquid supply port Li2 is provided at the pump upstream side end of the supply path L2. The pump downstream ends of the supply paths L1 and L2 merge in a Y shape at the junction L3, continue to the mixing channel L4, and reach the liquid outlet Lo at the channel end.

The flow paths L1 to L4 are, for example, 150 μm wide and 170 μm deep. The external dimensions of the microchip MT are, for example, about 20 mm × 40 mm × 0.5 mm. However, dimensions and shapes are not limited to this.
The pumps Pa and Pb show the structure and operation shown in FIG. 9. In this chip, the alternating voltage is applied to the piezoelectric elements PZTa and PZTb of each pump from the drive unit to supply the first and second from the supply ports Li1 and Li2. The liquid can be sucked, fed, and joined at the junction L3, mixed in the mixing channel L4, and discharged from the liquid outlet Lo.

The manufacturing process of the microchip MT will be described with reference to FIG. FIG. 11 representatively shows a manufacturing method of the portion of the cut end surface along the α-α line of FIG.
As shown in FIG. 11A, a silicon substrate SiS is prepared. As the silicon substrate SiS, for example, a silicon wafer having a thickness of 200 μm is used. Next, as shown in FIG. 11B, silicon oxide films SiO ₂ are formed on the upper and lower surfaces of the silicon substrate SiS. For example, the oxide films are formed by thermal oxidation so that each thickness becomes 1.7 μm. Next, a resist is applied on the upper surface to form a mask having a predetermined pattern, exposed with the mask pattern, and then developed to etch the oxide film. Then, after removing the resist on the upper surface, the resist is applied again, and exposure, development, and etching are performed. As a result, as shown in FIG. 11C, a portion a from which the oxide film has been completely removed and a portion b from which the oxide film has been removed halfway in the thickness direction are formed.

  For resist application, for example, a resist such as OFPR800 manufactured by Tokyo Ohka Co., Ltd. is used and spin-coated by a spin coater, and the thickness of the resist film is set to 1 μm, for example. Exposure is performed by an aligner, and development is performed by a developer. For example, reactive ion etching (RIE) is used for etching the oxide film. For stripping the resist, a stripping solution such as sulfuric acid / hydrogen peroxide is used.

  Next, as shown in FIG. 11D, after the silicon etching is partially performed on the upper surface, the oxide film in the portion b is completely removed by etching, and the silicon etching is performed again, as shown in FIG. In this way, a part a ′ obtained by etching the silicon substrate SiS by 170 μm and a part a ″ obtained by etching 25 μm are formed. For the silicon etching, for example, an etching method using ICP (High Frequency Inductively Coupled Plasma) is used. Furthermore, the oxide film is completely removed using, for example, BHF as shown in FIG.

Next, as shown in FIG. 11F, an electrode film e (for example, an ITO film) is formed on the lower surface of the silicon substrate. Then, as shown in FIG. 11G, a glass plate GL is attached to the upper surface of the silicon substrate. This pasting is performed, for example, by anodic bonding at 1200 V and 400 ° C. Finally, as shown in FIG. 11H, a piezoelectric element is bonded to the diaphragm portion of the pump chamber PC.
By the manufacturing method according to the manufacturing method described above, a large number of micropumps and liquid flow paths in the liquid feeding device, the liquid mixing device, the micropump unit, etc. according to the present invention can be manufactured with a uniform performance with little variation.

The liquid feeding method and apparatus, the liquid mixing method and apparatus of the present invention can be used for feeding and mixing dilution of liquid fuel and its diluting liquid in a fuel cell device, as well as medical treatment such as biochemical tests, immunological tests, genetic tests, etc. It can be used in various fields such as fields, environmental analysis, chemical synthesis and new drug discovery.
Further, the fuel cell device according to the present invention may be used as a power source mounted on, for example, a portable device.

It is a figure which shows one example of the liquid mixing apparatus using one example of the liquid feeding apparatus which can implement the liquid feeding method which concerns on this invention. It is a figure which shows one example of the drive waveform of the micropump in the liquid mixing apparatus shown in FIG. 3A is a diagram showing a modification of the liquid mixing apparatus shown in FIG. 1, and FIG. 3B is a diagram showing another modification of the liquid mixing apparatus shown in FIG. It is a figure which shows the other example of the drive waveform of a micropump. It is a figure which shows the further another example of the drive waveform of a micropump. It is a figure which shows the further another example of a liquid mixing apparatus. FIG. 7A shows an example of a fuel cell device using the liquid mixing device of FIG. 6, FIG. 7A is a plan view thereof, FIG. 7B is a side view thereof, and FIG. 7C is a bottom view thereof. is there. 8A is a cross-sectional view taken along the line AA of FIG. 7B, FIG. 8B is a cross-sectional view taken along the line BB of FIG. 7B, and FIG. 8C is a cross-sectional view of FIG. CC sectional view, FIG.8 (D) is the DD sectional view taken on the line of FIG. 7 (B). FIG. 9A shows a liquid discharge operation, FIG. 9B shows a liquid suction operation, and FIG. 9C shows such a liquid pumping operation. It is a figure which shows the voltage waveform applied to the piezoelectric element for discharge operation | movement and attraction | suction operation | movement. 9D is a diagram showing a liquid ejection operation in the opposite direction to FIG. 9A, FIG. 9E is a diagram showing a liquid suction operation in the opposite direction to FIG. 9B, and FIG. F) is a diagram showing a waveform of a voltage applied to the piezoelectric element for the opposite operation. FIG. 10A shows a reference microchip for explaining an example of a manufacturing method for a liquid mixing device, etc. FIG. 10A is a plan view thereof, FIG. 10B is a side view thereof, and FIG. It is XX sectional drawing of B). It is a figure which shows the example of a manufacturing process of a microchip. FIG. 2 is a diagram illustrating a possible example of a fuel cell device that employs a fuel cell that uses liquid fuel as fuel, dilutes the liquid fuel with a diluting liquid, and supplies the diluted liquid fuel to the fuel cell.

Explanation of symbols

100, 100 ′, 100a Liquid mixing devices P1 to P11 Micropump f1 First throttle channel for liquid suction f2 Second throttle channel for liquid discharge PC Pump chamber DF Flexible wall (diaphragm) of pump chamber PZT Piezoelectric element 11 First liquid supply port 12, 13 First liquid flow path 14 Second liquid supply port 15, 151, 16, 161, 17, 171, 18, 181 Second liquid flow path 19 Merge section 20, 200 Mixing flow path 21 Liquid outlet 100 ”Liquid mixer 141 Liquid channel 142 Second liquid supply port C1 Fuel cell device 1 First pump unit 11A, 12A Pump unit member 143 Channel 144 Dilution liquid receiving part 121, 122 Diluted liquid Fuel passage 123 Through hole 124 Gas vent hole 125 Through hole GD Gas flow part 2 Second pump unit 21A, 22A Pump unit Member 211, 212 liquid (water) passage 213 through-hole 214 air intake hole 215 through-hole PX micropump 221 liquid recovery passage 222 liquid receiving part 223 liquid discharge part 3 fuel cell 31 electrolyte membrane 32 fuel electrode 33 air electrode 34 Liquid passage MT Microchip Pa, Pb Micropump PZTa, PZTb Piezoelectric element L1, L2 Liquid supply path L3 Junction portion L4 Mixing flow path Li1, Li2 Liquid supply port Lo Liquid outlet SiS Silicon substrate

C Fuel cell L Load t1 Fuel tank t2 Recovery tank MX Mixer (mixing tank)
PM1 to PM3 Pump CONT Controller DS Concentration detection sensor

Claims (24)

A liquid feeding method for feeding two or more liquids at a predetermined liquid feeding rate.
One or two or more liquid feeding micropumps are provided for each of the two or more liquids, and a plurality of liquid feeding micropumps are provided for at least one of the two or more liquids. Provided, and all the micropumps for liquid delivery have the same performance,
For a liquid provided with one micropump, the one micropump is operated, and for each liquid provided with two or more micropumps, the liquid supply ratio is selected from the two or more micropumps. A liquid feeding method, wherein the number of micropumps to be operated is determined and the number of micropumps is operated to feed the two or more liquids at a predetermined liquid feeding rate.   Each of the two or more liquids is provided with a plurality of the liquid-feeding micropumps, and each liquid is operated according to the liquid-feeding ratio from among the plurality of micropumps provided for the liquids. The liquid feeding method according to claim 1, wherein the number of micropumps to be determined is determined and the number of micropumps is operated to feed the two or more liquids at a predetermined liquid feeding rate. It is a liquid mixing method in which two or more kinds of liquids are sent and mixed at a predetermined feeding rate,
One or two or more liquid feeding micropumps are provided for each of the two or more liquids, and a plurality of liquid feeding micropumps are provided for at least one of the two or more liquids. And providing a common mixing channel that communicates with each of the two or more liquid pumps provided for each of the two or more liquids, and each of the liquid pumps has the same performance,
For a liquid provided with one micropump, the one micropump is operated, and for each liquid provided with two or more micropumps, the liquid supply ratio is selected from the two or more micropumps. A liquid characterized by determining the number of micropumps to be operated and operating the number of micropumps so that the two or more types of liquids are sent to the mixing flow path at a predetermined liquid feeding ratio to be combined and mixed. Mixing method.   Each of the two or more liquids is provided with a plurality of the liquid-feeding micropumps, and each liquid is operated according to the liquid-feeding ratio from among the plurality of micropumps provided for the liquids. 4. The liquid mixing according to claim 3, wherein the number of micropumps to be determined is determined and the number of micropumps is operated so that the two or more kinds of liquids are sent to the mixing flow path at a predetermined liquid feeding ratio to be combined and mixed. Method. A liquid feeding device for feeding two or more kinds of liquids at a predetermined liquid feeding rate,
One or two or more liquid-feeding micropumps are provided for each of the two or more liquids, and at least one of the two or more liquids is used for feeding a plurality of liquids. A liquid feeding device comprising a micropump, and any liquid feeding micropump is a pump having the same performance.   The liquid feeding device according to claim 5, wherein a plurality of liquid feeding micropumps are provided for each of the two or more kinds of liquids.   Each of the micropumps includes a first throttle channel for sucking liquid, a second throttle channel for discharging liquid, a pump chamber between the first and second throttle channels, and a flexibility of the pump chamber. A piezoelectric element installed on the conductive wall, the pump chamber is vibrated by the piezoelectric element to contract and expand the pump chamber, and the liquid is sucked into the pump chamber from the first throttle channel. The liquid delivery device according to claim 5 or 6, wherein the liquid delivery device is a pump that discharges liquid in the pump chamber from the two throttle channels.   A pump drive unit for applying an alternating voltage to the piezoelectric element of the micropump to drive the pump is provided, and the pump drive unit applies an alternating voltage having a frequency of 20 kHz or more to the piezoelectric element. Item 8. The liquid feeding device according to Item 7. A liquid mixing device that sends and mixes two or more liquids at a predetermined liquid feeding ratio,
One or two or more liquid-feeding micropumps are provided for each of the two or more liquids, and at least one of the two or more liquids is used for feeding a plurality of liquids. A micro-pump is provided, and a common mixing channel is provided to communicate with each of the liquid-feeding micropumps provided for each of the two or more kinds of liquids. A liquid mixing apparatus characterized in that the pump is also a pump having the same performance.   The liquid mixing apparatus according to claim 9, wherein a plurality of the liquid-feeding micropumps are provided for each of the two or more liquids.   The liquid mixing apparatus according to claim 9 or 10, wherein the mixing flow path meanders.   Each of the micropumps includes a first throttle channel for sucking liquid, a second throttle channel for discharging liquid, a pump chamber between the first and second throttle channels, and a flexibility of the pump chamber. A piezoelectric element installed on the conductive wall, the pump chamber is vibrated by the piezoelectric element to contract and expand the pump chamber, and the liquid is sucked into the pump chamber from the first throttle channel. The liquid mixing apparatus according to claim 9, 10 or 11, which is a pump that discharges liquid in a pump chamber from a two-throttle channel.   A pump drive unit for applying an alternating voltage to the piezoelectric element of the micropump to drive the pump is provided, and the pump drive unit applies an alternating voltage having a frequency of 20 kHz or more to the piezoelectric element. Item 13. A liquid mixing apparatus according to Item 12.   A fuel cell in which liquid fuel is used as a fuel is employed, and the liquid fuel and dilution liquid are supplied at a predetermined liquid feed ratio and mixed to dilute the liquid fuel, and the diluted liquid fuel is supplied to the fuel cell. A fuel cell device to be supplied, wherein a first pump unit is stacked on the fuel cell, and the first pump unit includes one or two or more liquid feeding micros for each of the liquid fuel and the diluting liquid. A pump, and at least one of the liquid fuel and the diluting liquid has a plurality of liquid-feeding micropumps, and each of the liquid fuel and the diluting liquid. Each of the liquid-feeding micropumps provided in common, and supplying a diluted liquid fuel to the fuel cell from the mixed flow-path. Same pump Fuel cell system which is a pump.   A second pump unit is stacked on a surface of the fuel cell opposite to the surface on which the first pump unit is stacked, and the second pump unit receives at least a liquid generated by an electrochemical reaction in the fuel cell. The fuel cell device according to claim 14, which is to be recovered.   The second pump unit supplies the recovered liquid as a dilution liquid to the first pump unit via a dilution liquid circulation path formed in a stack of the fuel cell, the first pump unit, and the second pump unit. The fuel cell device according to claim 15.   The fuel cell device according to claim 15, wherein the second pump unit sends the recovered liquid as a dilution liquid to a recovery container, and the first pump unit is supplied with the dilution liquid from the recovery container.   The second pump unit is stacked adjacent to the air electrode on the fuel cell, has a liquid passage to be collected on a surface facing the air electrode, and a surface facing the air electrode; Has a liquid recovery path including a liquid recovery micropump for recovering the liquid on the opposite side portion, and further has a path leading from the liquid path facing the air electrode to the liquid recovery path, 18. The fuel cell device according to claim 15, 16 or 17, further comprising an air intake hole for supplying air from the outside to the air electrode via the liquid passage.   The first pump unit is stacked adjacent to the fuel electrode in the fuel cell, and has a diluted liquid fuel passage for supplying the diluted liquid fuel to the fuel electrode on a surface facing the fuel electrode. A liquid fuel supply path including the liquid-feeding micropump for supplying the liquid fuel to a portion opposite to the surface facing the fuel electrode, and for dilution including the liquid-feeding micropump for supplying the dilution liquid A liquid supply path and a liquid supply path for dilution and a liquid supply path for dilution, the mixing flow path communicating with the diluted liquid fuel path, and further diluting a gas generated at the fuel electrode. The fuel cell device according to any one of claims 14 to 18, further comprising a gas vent for discharging through the liquid fuel passage.   The fuel cell device according to any one of claims 14 to 19, wherein the mixing flow path of the first pump unit meanders.   Each of the micropumps includes a first throttle channel for sucking liquid, a second throttle channel for discharging liquid, a pump chamber between the first and second throttle channels, and a flexibility of the pump chamber. A piezoelectric element installed on the conductive wall, the pump chamber is vibrated by the piezoelectric element to contract and expand the pump chamber, and the liquid is sucked into the pump chamber from the first throttle channel. The fuel cell device according to any one of claims 14 to 20, wherein the fuel cell device is a pump that discharges liquid in a pump chamber from a two-throttle channel.   A pump drive unit for applying an alternating voltage to the piezoelectric element of the micropump to drive the pump is provided, and the pump drive unit applies an alternating voltage having a frequency of 20 kHz or more to the piezoelectric element. Item 22. The fuel cell device according to Item 21.   23. The fuel cell device according to claim 14, wherein the fuel cell is a direct methanol fuel cell, the liquid fuel is a methanol-containing liquid, and the dilution liquid is a liquid containing water. The fuel cell apparatus according to claim 23, wherein the direct methanol fuel cell has a membrane-electrode assembly (MEA) structure.