JP4517153B2 - Fluid control method and fluid device using the same - Google Patents

Description

  The present invention relates to a fluid control method and a fluid device using the same.

  When an electric field is applied to a certain kind of insulating liquid, a circulating flow or a secondary flow may be generated inside the fluid due to non-uniformity of conductivity and dielectric constant. This is called an electrohydrodynamic effect (Electrohydrodynamic effect, hereinafter referred to as “EHD effect”).

  For example, Patent Documents 1 to 12 disclose a technique for generating a high-speed jet water flow by applying a voltage to an insulating liquid.

Japanese Patent No. 2817654 Japanese Patent No. 3109268 Japanese Patent No. 3109273 Japanese Patent No. 3157804 Japanese Patent No. 3179015 Japanese Patent No. 3179016 Japanese Patent No. 3179035 Japanese Patent No. 3224985 Japanese Patent No. 3225015 Japanese Patent No. 3225016 Japanese Patent No. 3245386 Japanese Patent No. 3263346

  However, all of the above patent documents are insulating oils, etc., which are flammable, odorous, restricted when disposed as environmental pollutants, highly volatile, in handling plastics, etc. Issues remain.

  Accordingly, an object of the present invention is to solve the above-described problems and provide a fluid control method and a fluid device that are easier to handle.

  The inventors of the present invention have made extensive studies on the above-mentioned problems, paying attention to the fact that water is the easiest to handle, and conducted trial and error experiments to elucidate that it can function as a fluid device even in water. The present invention has been completed.

  That is, as a first means for solving the above-described problem, the fluid control method uses a pair of electrodes in water and generates a water flow by applying a DC voltage.

In this means, the water flow is preferably a jet water flow, and the voltage applied between the pair of electrodes is preferably 1 kV or more and 8 kV or less, and the distance between the pair of electrodes is cylindrical. When combining an electrode and a needle electrode, it is desirable that it is 0 or more and 1 cm or less, and when combining a needle electrode and an electrode group which bundled a plurality of needle electrodes, it is larger than 0 and 1 cm or less. In addition, when the electric field is applied in the range of 20 kV / m or more and 70 kV / m or less, the conductivity of water is greater than 0 and 1 mS / m or less, and more preferably 10 ⁻⁵ S / m or more and 1 mS / m or less. It is desirable that

  In this means, it is desirable that the pair of electrodes include a cylindrical electrode and a needle-like electrode. Further, the needle-like electrode has a tip portion exposed and a portion other than the tip portion is an insulator. It is desirable to be coated with. It is more desirable to make the voltage of the cylindrical electrode higher than the voltage of the needle electrode.

  In addition, as another means for solving the above-described problem, the fluid device includes a housing capable of storing water and a pair of electrodes disposed in the housing.

In this means, it is desirable to generate a jet water flow, and the voltage applied between the pair of electrodes is desirably 1 kV or more and 8 kV or less. The distance between the pair of electrodes is as follows. When combining needle-shaped electrodes, it is desirable to be 0 or more and 1 cm or less, and when combining a needle-shaped electrode and an electrode group in which a plurality of needle-shaped electrodes are combined, it is greater than 0 and 1 cm or less. Also, the conductivity of the water to be stored is greater than 0 and less than or equal to 1 mS / m, more desirably between 10 ⁻⁵ S / m and 1 mS when an electric field is applied in the range of 20 kV / m to 70 kV / m. / M or less is desirable.

  Further, in this means, the pair of electrodes includes a cylindrical electrode and a needle-like electrode, and the needle-like electrode has a tip portion exposed and a portion other than the tip portion is covered with an insulator. It is also desirable to have a power supply device that is connected to a pair of electrodes and makes the voltage of the cylindrical electrode higher than the voltage of the needle electrode.

  As described above, the present invention can provide a fluid control method that is easier to handle and a fluid device using the fluid control method.

  Embodiments of the present invention will be described below with reference to the drawings. However, the present invention can be implemented in many different modes and is not limited to the embodiments shown below. Note that in this specification, portions having the same or similar functions are denoted by the same reference numerals, and repeated description thereof is omitted.

(Embodiment 1)
FIG. 1 shows a schematic diagram of a fluidic device according to this embodiment. A fluidic device 1 according to the present embodiment (hereinafter referred to as “the present fluidic device”) includes a housing 2 and a pair of electrodes 3 disposed in the housing. The fluidic device can be used as an inkjet device. By adopting such a configuration, the fluid device 1 supplies water between the pair of electrodes, applies a voltage to generate a jet water flow, and functions as a fluid device.

  The housing 1 according to the present embodiment is not particularly limited, but preferably has at least two openings so that water can be sucked and discharged, for example, as shown in FIG. It is desirable that it is cylindrical with both ends open. Further, the material of the housing 2 is not particularly limited, but is preferably an insulating material so as not to affect the voltage applied by the pair of electrodes 3 disposed therein, for example, glass or Various things such as plastic can be suitably used.

  The pair of electrodes 3 arranged inside the housing 1 are for generating an electric field in water filled between them, and a jet water flow can be generated using the electric field. The pair of electrodes 3 includes a cylindrical electrode 31 and a needle electrode 32 as shown in FIG. 1, and these electrodes are arranged with a predetermined interval. The cylindrical electrode 31 has an opening for allowing a jet water flow generated by the generation of an electric field to pass therethrough, and the material is not particularly limited as long as it has conductivity, such as copper or aluminum. Metals, alloys thereof and the like can be used publicly. Further, the needle electrode 32 is preferably as thin as possible so as not to hinder the jet water flow flowing into the cylindrical electrode 31, and the same material as the cylindrical electrode 31 can be used. In particular, in this fluid device, water is used, and in order to generate a jet flow in the water, the needle electrode 32 has a sharp needle shape at the tip portion, and an insulating material is used for portions other than the tip portion. It is highly desirable that it be coated. By covering with an insulator, the electric field can be concentrated in the vicinity of the tip, and the non-uniformity of the electric field in water can be improved to efficiently generate a jet flow. The length of the exposed tip portion is preferably 5 mm or less from the tip, more preferably 3 mm or less, depending on the strength of the electric field generated between the pair of electrodes. FIG. 2 shows an enlarged view of an example of the needle-like tip portion. Moreover, since it is necessary to apply a voltage to each of the pair of electrodes, it is necessary to be connected to a power supply outside the housing through wiring (not shown).

  In the fluid device, a desirable range of the distance between the pair of electrodes is preferably greater than 0 and 1 cm or less, more preferably 5 mm or less, in order to avoid a short circuit between the electrodes and apply a sufficient voltage. More desirably, it is 3 mm or less. The distance between the voltages is not limited to the following. For example, when the pair of electrodes is a needle electrode and a cylindrical electrode (described later), the central axis of the cylindrical electrode and the opening on the side close to the electrode The distance between an imaginary point where the plane intersects and the tip of the needle electrode is referred to. In particular, in the case of a combination of a needle electrode and a cylindrical electrode, 0 may be included. Further, when the pair of electrodes is an electrode group in which a needle-like electrode and at least one needle-like electrode are combined, the shortest of the distances between the tips of the opposing needle-like electrodes is meant.

  In addition, the voltage applied between the electrodes is preferably 1 kV or more and 8 kV or less within the above-described desirable range. However, since the strength of the electric field greatly affects the conditions for generating the jet water flow, the voltage applied between the pair of electrodes divided by the distance between the pair of electrodes is 300 kV / m or more and 3000 kV / m or less, more preferably 2500 kV / m or less.

The fluid device can generate a jet water flow by increasing the voltage applied to the cylindrical electrode rather than the needle electrode. The strength of the generated electric field depends on the distance between the electrodes, but greatly depends on the electric field strength and the conductivity. The electric field strength is preferably 20 kV / m or more and 70 kV or less, for example, and the water conductivity is preferably 1 mS / m or less, more preferably 10 ⁻⁵ S / m under the above electric field strength. It is 1 mS / m or less. The electric field strength in the measurement of conductivity can be obtained by arranging a pair of flat plates at a certain distance and applying a voltage between them.

  As described above, according to the fluid device and the fluid control method according to the present embodiment, since water is used as the working liquid, handling becomes easier, and the application range can be greatly expanded.

(Experimental example)
In order to confirm the effect of the fluid device, an actual fluid device model was created and the effect was confirmed. This will be specifically described below.

  First, a cylindrical tube made of copper in which tin plating with an outer diameter of 4.0 mm, an inner diameter of 2.4 mm, and a length of 8.0 mm is performed in a silicone tube 21 having an inner diameter of 4.0 mm, an outer diameter of 6.0 mm, and a length of 370 mm. 31 and a copper needle-like electrode 32 having a diameter of 0.12 mm and a length of 1.0 mm were arranged on the lower side thereof with an interval of 3.0 mm. And after joining conducting wire to each electrode, the exposed metal surface outside the cylinder was insulated and fixed using the arm of the stand to obtain a fluid device. In this embodiment, the needle electrode 32 has a shape in which only the tip portion is exposed by 1 mm.

Then, a glass reservoir 4 was prepared in the lower part, and water was poured so that the water surface was positioned at 1 cm on the upper surface of the cylindrical electrode (see FIG. 3). Thereafter, the fluid device thus created was connected to the power source 5 through a conductive wire, and a voltage was applied with the needle-like electrode being minus (earth) and the upper cylindrical electrode being plus. Here, as water, three types of water, tap water, distilled water, and ion exchange water, were used, and the elevation of the water surface was measured for each of them. The result is shown in FIG.
In the horizontal axis of this figure, the value obtained by dividing the applied voltage by the electrode spacing (3.0 mm) is shown as the electric field strength.

  According to the result of FIG. 4, in tap water, an excessive current flows due to the influence of the electrolyte in the water, so that it was possible to apply only up to a voltage of 0.2 kV, and no rise in the water level was observed. On the other hand, distilled water and ion-exchanged water could be measured in the range up to 7 kV, and it was confirmed that the water surface increased as the voltage increased. In addition, in the case of 7 kV, after the water surface in the tube reached the highest point by applying a voltage, the water surface gradually dropped even if the voltage was kept constant. However, on the contrary, an increase in current could be confirmed. When a voltage of 7 kV was applied, distilled water showed 0.2 mA and ion exchange water showed 1.2 mA. However, when a voltage higher than 7 kV was applied and the current exceeded 3 mA, discharge occurred. With that, the water surface fluctuated violently, and stable data could not be obtained. From FIG. 4, it was confirmed that the water surface of ion-exchanged water was higher than that of distilled water.

  In addition to the above results, the electric field strength dependence of conductivity was further investigated. The result is shown in FIG. As a result, it was confirmed that the conductivity of distilled water was lower than that of tap water, and that ion-exchanged water was lower than the conductivity of distilled water. As a result, the desirable water conductivity range is desirably 1 mS / m or less, and more desirably 0.5 mS / m or less, within an electric field strength range of 20 kV / m to 70 kV / m. . The electric field strength in this case refers to a value obtained by applying a voltage to a pair of conductive plates arranged opposite to each other and dividing by a distance between the conductive plates (here, measured using a disc having a radius of 3.5 mm). ).

The fluid device can also be applied as an ink jet device, and its configuration is shown in FIG. The fluidic device shown in FIG. 6 is characterized in that a nozzle 6 is further arranged in addition to the above structure. And when ion-exchange water was applied to this device and a voltage of 7 kV was applied, ejection of 2.0 × 10 ³ mm ³ per second and a height of 33 mm was confirmed in the direction from the needle electrode to the cylindrical electrode. As a result, application as an inkjet device was confirmed.

(Embodiment 2)
The present embodiment is an example in which the fluid device is applied to a motor. The fluid device according to the present embodiment also includes a housing 2 that can store water, and a pair of electrodes 3 disposed in the housing. It is characterized by having. FIG. 7 shows a schematic cross-sectional view of the fluidic device according to the present embodiment, FIG. 8 shows a top view of the fluidic device, and a partially enlarged view thereof.

  As shown in FIGS. 7 and 8, the fluid device 1 includes a cylindrical housing 8 that can store water, a central shaft 9 disposed in the housing 8, and a plurality of blades connected to the central shaft 9. 10 and a pair of electrodes 3 formed on a plane which is an outer peripheral portion of the housing 8 and is perpendicular to the central axis. Water is accommodated in the housing 8, and a jet water flow is generated by applying a voltage to the pair of electrodes, and the blades and the rotating shaft can be rotated to function as a motor.

  Although the material of the housing 8 can be the same as that of the first embodiment, the housing 8 in the present embodiment does not necessarily discharge water, and therefore an opening is not always necessary. However, in order to arrange the central shaft 9 and the plurality of blades 10, it is desirable to have a cylindrical shape and at least a bottom portion that supports the central shaft. In addition, when water is left in the air, conductivity may increase due to impurities in the air. Therefore, it is preferable to have a lid and a sealed structure.

  The central shaft 9 is disposed along the axis of the housing 8 having a cylindrical shape, and a plurality of blades 10 are connected thereto. The material of the central shaft 9 and the blade 10 is not particularly limited, but it is extremely desirable to have an insulating property so as not to affect the voltage applied by the electrode. For example, plastic can be suitably used. And in this fluid device, by generating an electric field between a pair of electrodes, a jet water flow is generated like the previous embodiment, a blade is rotated, and it can function as a motor.

  The pair of electrodes may be a pair of a cylindrical electrode and a needle-like electrode as in the first embodiment. However, in the present fluid device, it is not necessary to discharge water. Good. In the present embodiment, as the pair of electrodes 3, a needle electrode 33 and a composite electrode 34 in which a plurality of needle electrodes are combined are used. The composite electrode 34 is bent toward the needle electrode side 34 in the housing 8.

  As described above, according to the fluid device and the fluid control method according to the present embodiment, since water is used as the working liquid, handling becomes easier, and the application range can be greatly expanded.

(Example 2)
In order to confirm the effect of the fluid device according to Embodiment 2, a fluid device was actually created and the effect was confirmed.

  In the fluidic device according to the present embodiment, the inner diameter of the housing is 12.5 mm, the length is 40 mm, the blades are 8 mm wide and 30 mm long, and are shifted by 45 degrees to the central axis of 8 mm. Connected. As a pair of electrodes, a needle-like electrode having a diameter of 0.12 mm and a tip portion exposed by 1 mm, and an electrode group in which ten needle-like electrodes having a diameter of 0.12 mm and a tip portion exposed by 3 mm are bundled, These were placed 3 mm apart. The housing 8 was filled with water so that all the blades were immersed in water.

  Here, the relationship between the voltage and the rotation speed in the operation of the fluid device using distilled water as water was examined. FIG. 9 shows the result. The number of rotations was determined by taking a picture of the motor rotating with a high-speed camera 10 seconds after applying the voltage, and determining the number of rotations of the motor. As a result, when the voltage was high, the rotational motion started almost simultaneously with the application, and at this time the rotor rotated counterclockwise. The number of rotations increased with a voltage in a quadratic function, and the faster the rotation at higher voltages, for example, about 300 rpm at 7 kV. This result was close to a practical motor. The current at this time was 0.7 mA per set, and the power consumption of the entire motor was about 10 W.

  As described above, the usefulness of the fluid device and the fluid control method in the above embodiment could be confirmed.

  As described above, according to the present invention, it can be industrially used as a fluid control method and a fluid device. More specifically, it can be used industrially as a product such as a motor, a pump, or an ink jet device.

1 is a perspective view of a fluidic device according to Embodiment 1. FIG. The elements on larger scale of the front-end | tip part of the acicular electrode which concerns on Embodiment 1. FIG. 1 is a schematic diagram of a fluidic device according to Embodiment 1. FIG. The figure which shows the relationship between the electric field strength and height in the fluidic device which concerns on Example 1. FIG. FIG. 4 is a diagram illustrating a relationship between electric field strength and dielectric constant in the fluidic device according to the first embodiment. The figure at the time of using the fluidic device which concerns on Embodiment 1 for an inkjet device. Sectional drawing of the fluidic device which concerns on Embodiment 2. FIG. FIG. 6 is a top view of a fluidic device according to a second embodiment. The figure which shows the relationship between the voltage in the fluidic device which concerns on Example 2, and rotation speed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fluidic device, 2 ... Housing, 3 ... Pair of electrodes, 4 ... Reservoir, 5 ... Power supply, 6 ... Nozzle, 8 ... Housing, 9 ... Center axis, 10 ... Blade, 21 ... Silicone tube, 31 ... Cylindrical electrode 32 ... acicular electrodes

Claims (6)

A fluid control method for generating a jet water flow by placing a pair of electrodes having a cylindrical electrode and a needle electrode in water and applying a DC voltage ,
The conductivity of the water is 10 ⁻⁵ S / m or more and 1 mS / m or less when an electric field is applied in a range of 20 kV / m or more and 70 kV / m or less,
A fluid control method in which a distance between the cylindrical electrode and the needle electrode is greater than 0 and 1 cm or less, and a voltage of 1 kV or more and 8 kV or less is applied therebetween . It said needle electrode is exposed tip portion, a fluid control method according to claim 1, wherein portions other than the tip portion, characterized in that it is covered by an insulator. Fluid control method according to claim 1, wherein the higher than the voltage of the voltage the needle electrode of the tubular electrode. Water cylindrical housing capable of accommodating a possess a pair of electrodes and having a cylindrical electrode and the needle electrode disposed within said housing, a fluid device for generating a jet stream,
The electrical conductivity of the water is 10 ⁻⁵ S / m or more and 1 mS / m or less when an electric field is applied in the range of 20 kV / m or more and 70 kV / m or less,
A fluid device in which a distance between the cylindrical electrode and the needle electrode is greater than 0 and equal to or less than 1 cm . The fluid device according to claim 4 , wherein a tip portion of the needle electrode is exposed and a portion other than the tip portion is covered with an insulating material. A power supply device that is connected to the pair of electrodes, applies a voltage of 1 kV to 8 kV between the cylindrical electrode and the needle electrode, and makes the voltage of the cylindrical electrode higher than the voltage of the needle electrode The fluidic device according to claim 4, wherein: