Electrohydrodynamic pump

Abstract

To provide an electro-hydrodynamic pump allowing for easily changing a discharge characteristic.SOLUTION: An electro-hydrodynamic pump 1 according to an embodiment of the present invention is an electro-hydrodynamic pump that generates a flow in an object fluid by applying a voltage to the object fluid having an insulation property. The electro-hydrodynamic pump comprises: a plurality of action parts 11 arranged in series, applying the voltage to the object current, and each having a flow channel member 112a that defines an action channel 111 applying the voltage to the object fluid and a pair of electrodes 113 and 114 applying an electric field to the action channel 111; and a driving circuit 20 individually applying the voltage to the plurality of action parts 11.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electrohydrodynamic pump.

Background Art

[0002] An electrohydrodynamic effect is known in which a flow is generated in a fluid by applying a voltage to the insulating fluid. An electrohydrodynamic pump that discharges a fluid using this electrohydrodynamic effect has been proposed. Since the electrohydrodynamic pump does not require a moving member such as an impeller, it can be miniaturized.

[0003] In an electrohydrodynamic pump, in order to increase the discharge amount and the discharge pressure, it is effective to increase the voltage. However, increasing the voltage may cause the circuit to be expensive and the surrounding metal to be easily affected. As a method of increasing the discharge amount and the discharge pressure while suppressing the voltage, an electrohydrodynamic pump has been proposed in which a plurality of electrode pairs are arranged in multiple stages along the flow path and the fluid is pressurized in order by the plurality of electrode pairs (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] If the number and arrangement of the electrode pairs are designed and changed according to the required specifications, the electrohydrodynamic pump will become expensive. Therefore, an object of the present invention is to provide an electrohydrodynamic pump that can easily change the discharge characteristics.

Means for Solving the Problems

[0006] An electrohydrodynamic pump according to one aspect of the present invention is an electrohydrodynamic pump that generates a flow in a target fluid by applying a voltage to the insulating target fluid, and includes a flow path forming member that defines a working flow path for applying a voltage to the target fluid and a pair of electrodes that apply an electric field to the working flow path, which are arranged in series and include a plurality of working units that apply a voltage to the target fluid, and a drive circuit that individually applies a voltage to the plurality of working units.

[0007] In the above-described electrohydrodynamic pump, the drive circuit may individually apply or cut off a constant voltage to the plurality of working units.

[0008] In the above-described electrohydrodynamic pump, the working unit may be configured by a separable module.

[0009] In the above-described electrohydrodynamic pump, the plurality of working units may include those having different shapes of the working flow path.

Advantages of the Invention

[0010] According to the present invention, an electrohydrodynamic pump whose specifications can be easily changed can be provided.

Brief Description of the Drawings

[0011]

Figure 1

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of an electrohydrodynamic pump 1 according to an embodiment of the present invention.

[0013] The electrohydrodynamic pump 1 in FIG. 1 is a pump that generates a flow in a target fluid by applying a voltage to the insulating target fluid. The electrohydrodynamic pump 1 includes a pump body 10 and a drive circuit 20.

[0014] The pump body 10 includes a plurality of working parts 11 arranged in series, each applying a voltage to the target fluid, and a plurality of connection members 12 connecting adjacent working parts 11 to each other. That is, in the present embodiment, each working part 11 is composed of a separable module. Since the pump body 10 having a plurality of working parts 11 arranged in series can pressurize the target fluid step by step, the discharge pressure of the electrohydrodynamic pump 1 can be increased. Note that the illustrated pump body 10 has three working parts 11, but the number of working parts 11 is not particularly limited. Further, the electrohydrodynamic pump 1 can easily change the discharge characteristics by adjusting the number of working parts 11 constituting the pump body 10, so that electrohydrodynamic pumps 1 of various specifications can be supplied relatively inexpensively.

[0015] The working part 11 is formed of an insulating material, and includes a channel forming member 112 defining a working channel 111 for applying a voltage to the target fluid, a pair of electrodes (a first electrode 113 and a second electrode 114) applying an electric field to the working channel 111, a cylindrical casing part 115 formed of an insulating material and housing the channel forming member 112, and a pair of fixed structure parts 116 provided integrally at both ends of the casing part 115 and held by the connection member 12.

[0016] In the electrohydrodynamic pump 1, it is preferable that the casing parts 115 and the fixed structure parts 116 of each working part 11 all have the same shape, but the channel forming member 112 (particularly the working channel 111) and the electrodes 113, 114 may have different shapes for each working part 11. That is, the pump body 10 can be formed by combining working parts 11 having different shapes of the working channel 111. The characteristics of the pump body 10 will vary depending on the combination of the working parts 11. Therefore, by preparing a relatively small number of working parts 11 with different specifications and simply selecting their combinations, various electrohydrodynamic pumps 1 can be realized.

[0017] In the pump body 10 of FIG. 1, all the components of the first working part 11 and the third working part 11 have the same shape when counted from the upstream side. However, the second working part 11 has a first electrode 113, a second electrode 114, a casing part 115, and a fixing structure part 116 having the same shape as those of the first and third working parts 11, but has a flow path forming member 112 (particularly the working flow path 111) having a shape different from that of the first and third working parts 11. More specifically, the working flow paths 111 of the first and third working parts 11 are cylindrical flow paths with a constant diameter, while the working flow path 111 of the second working part 11 is a frustum-shaped flow path whose diameter decreases at a constant rate toward the downstream side. In the illustrated example, the first electrodes 113 and the second electrodes 114 of all the working parts 11 are the same, but the shape of either or both of the first electrode 113 and the second electrode 114 may be different corresponding to the working flow path 111.

[0018] When the working flow path 111 has a constant cross-sectional area, the flow path resistance is small, and a voltage is evenly applied to the target fluid, so a relatively large discharge flow rate can be obtained. On the other hand, when the cross-sectional area of the working flow path 111 decreases toward the downstream side, the pressure of the target fluid can be increased in the working flow path 111 to make the discharge pressure larger. By combining the working parts 11 having different shapes of the working flow path 111 like this, the pump body 10 having desired discharge characteristics can be obtained.

[0019] When increasing the differential pressure in the working part 11, it is preferable that the ratio of the diameter (equivalent circle diameter) of the inlet of the working flow path 111 to the diameter of the outlet is 5 or more and 20 or less, and more preferably 8 or more and 15 or less. As the ratio of the diameter of the working flow path 111 to the flow path length, for example, it can be 1 or more and 10 or less, preferably 2 or more and 8 or less. Within such a range, by increasing the reduction rate of the diameter per unit flow path length of the working flow path 111, the differential pressure in the working part 11 can be efficiently increased.

[0020] The flow path forming member 112 is disposed so as to divide the inside of the casing portion 115, and the working flow path 111 is formed to penetrate therethrough so as to communicate the upstream space and the downstream space of the casing portion 115. Further, the flow path forming member 112 preferably has a holding structure for holding the first electrode 113 and the second electrode 114 on both sides of the working flow path 111, respectively.

[0021] The flow path forming member 112 is preferably disposed so as not to form a gap with the casing portion 115 so that the target fluid can pass only through the working flow path 111. For this reason, the flow path forming member 112 can be formed integrally with the casing portion 115 by a method such as cutting. Further, in order to facilitate the formation of the working flow path 111 having various shapes, the flow path forming member 112 may be independently formed and then fixed inside the casing portion 115 by a method such as press-fitting.

[0022] A voltage with the first electrode 113 being negative is applied between the first electrode 113 and the second electrode 114. The first electrode 113 and the second electrode 114 have a shape that covers the inlet and outlet of the working flow path 111 and has an opening or gap through which the target fluid can pass, and is preferably in the form of a mesh having a large contact area with the target fluid. Specifically, the first electrode 113 and the second electrode 114 can be formed of a metal wire mesh, preferably a stainless steel wire mesh having relatively high strength. The first electrode 113 and the second electrode 114 are preferably arranged in parallel and substantially perpendicular to the flow direction of the target fluid.

[0023] As the aperture ratios of the first electrode 113 and the second electrode 114, those of 15% or more and 80% or less are preferable, those of 20% or more and 65% or less are more preferable, and those of 25% or more and 50% or less are even more preferable. By this, while suppressing an increase in the flow path resistance due to the first electrode 113, the contact area between the first electrode 113 and the target fluid can be secured, and a differential pressure can be applied to the target fluid. Further, the first electrode 113 and the second electrode 114 may partially have large openings or gaps in order to facilitate the flow of the target fluid. As a specific example, the first electrode 113 may be formed by forming an opening in a mesh-like material. Note that the aperture ratios of the first electrode 113 and the second electrode 114 may be different.

[0024] As the isolation distance in the flow path direction between the first electrode 113 and the second electrode 114 and the connection member 12, although it depends on the voltage applied to the first electrode 113 and the second electrode 114, for example, it can be set to be 2 times or more the distance between the first electrode 113 and the second electrode 114, specifically 10 mm or more.

[0025] The casing portion 115 extends in the front and rear in the flow path direction, and by securing the distances between the connection member 12 that may contain metal and the first electrode 113 and the second electrode 114, it becomes possible to form an ideal electric field in the working flow path 111 by the first electrode 113 and the second electrode 114 without being affected by the connection member 12. For this reason, the casing portion 115 defines flow paths having a larger cross-sectional area and a smaller flow path resistance than the working flow path 111 in front of and behind the working flow path 111.

[0026] The casing portion 115 has a wiring hole through which a wiring member for connecting the first electrode 113 and the second electrode 114 to the drive circuit 20 passes. This wiring hole may be sealed using a sealing material or the like in order to prevent leakage of the target fluid, or leakage of the target fluid may be prevented by providing a sealing structure in the wiring member or the flow path forming member 112.

[0027] The fixed structure portion 116 is preferably formed of an insulating material so as not to affect the electric field formed in the working flow path 111. Further, the fixed structure portion 116 is preferably formed integrally with the casing portion 115 in order to minimize the length of the working portion 11. Thereby, the pump body 10 having desired characteristics can be configured to be relatively small.

[0028] The fixed structure portion 116, together with the connecting member 12, preferably constitutes a structure similar to a pipe joint, that is, a joint structure for connecting pipes. This makes it possible to obtain members for connecting the working portion 11 such as the connecting member 12 at low cost and easily, and to connect the working portion 11 without special knowledge.

[0029] As a specific example, the fixed structure portion 116 may be, for example, a screw, a flange, etc., but is preferably a hose having a shape defined in ISO2852. By using a hose as the fixed structure portion 116, easy and reliable connection of the working portion 11 becomes possible. Further, by using a hose as the fixed structure portion 116, the fixed structure portion 116 is small and the amount of protrusion of the connecting member 12 toward the first electrode 113 and the second electrode 114 can be reduced, so that the working portion 11 can be miniaturized.

[0030] Also, the fixed structure portion 116 is also used for connecting the pump body 10 to the flow path of the target fluid at both ends of the pump body 10. Further, in order to connect to a flow path using a joint different from the fixed structure portion 116 of the pump body 10, an adapter (not shown) having a joint used for the flow path at one end and a structure similar to the fixed structure portion 116 at the other end may be used. Such an adapter may have a reducer for converting the diameter of the casing portion 115 to the diameter of the flow path.

[0031] The connecting member 12 connects two adjacent actuating portions 11 by holding two fixedly structured portions 116 arranged opposite to each other. As the connecting member 12, a member corresponding to the fixedly structured portion 116 is used. Further, the connecting member 12 can be formed of metal in order to firmly connect the actuating portions 11. As an example, when the fixedly structured portion 116 is a hose nipple, a hose clamp band defined in ISO2852 is used as the connecting member 12. Since the hose clamp band has a small width in the flow path direction, it hardly affects the electric field formed in the working flow path 111. Also, if the fixedly structured portion 116 is a screw, a socket or a union can be used as the connecting member 12, and if the fixedly structured portion 116 is a flange, a plurality of sets of bolts and nuts can be used as the connecting member 12.

[0032] A gasket 13 for sealing the gap between the actuating portions 11 may be interposed between the fixedly structured portions 116 of the two actuating portions 11 connected by the connecting member 12. The gasket 13 seals the gap between the actuating portions 11. As the gasket 13, a member corresponding to the fixedly structured portion 116 is also used. Further, the gasket 13 can be omitted depending on the configurations of the fixedly structured portion 116 and the connecting member 12.

[0033] The drive circuit 20 individually applies a voltage to a plurality of actuating portions 11. The illustrated drive circuit 20 individually applies or cuts off a constant voltage to a plurality of actuating portions 11. Specifically, the drive circuit 20 has a common power source 21 and a plurality of wiring portions 22 that connect the respective actuating portions 11 to the power source, and each wiring portion 22 is provided with a switch 23 that is independently controlled and can disconnect the actuating portion 11 from the power source 21, and can have a relatively simple configuration. By making it possible to select whether or not to apply a voltage to each actuating portion 11, the target fluid can be discharged at a desired flow rate and pressure without consuming more power than necessary. In particular, when the plurality of actuating portions 11 have working flow paths 111 of different shapes, a variety of discharge flow rates and discharge pressures can be selected by the combination of the actuating portions 11 to which a voltage is applied, so that a desired output characteristic can be efficiently realized by a drive circuit 20 having a relatively simple configuration.

[0034] The drive circuit 20 may be configured to be able to adjust the voltage applied to each of the actuating parts 11. As an example, in the illustrated circuit, by turning the switch 23 on and off at high speed and controlling its duty (the ratio of the on time), the effective value of the voltage applied to the actuating part 11 can be adjusted. Further, the drive circuit 20 may be configured to be able to adjust the value of the voltage continuously output, for example, by an operational amplifier or the like. Thus, by making it possible to adjust the voltage applied to the actuating part 11, it becomes possible to select the discharge flow rate and discharge pressure steplessly. Even in this case, by selecting the actuating part 11 to be driven, the effect of optimizing the relationship between the flow rate and the pressure or improving the energy efficiency can be obtained.

[0035] As described above, since the electrohydrodynamic pump 1 includes the drive circuit 20 that individually applies voltage to the plurality of actuating parts 11, the discharge characteristics can be easily changed by selecting the actuating part 11 to which the voltage is applied.

[0036] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be changed as appropriate.

[0037] In the electrohydrodynamic pump according to the present invention, the actuating part may be configured to be inseparable. Further, the electrohydrodynamic pump according to the present invention may include a module having two or more actuating parts.

Explanation of reference numerals

[0038] 1 Electrohydrodynamic pump 10 Pump body 11 Actuating part 111 Actuating flow path 112 Flow path forming member 113 First electrode 114 Second electrode 115 Casing part 116 Fixed structure part 12 Connecting member 13 Gasket 20 Drive circuit 21 Power supply 22 Wiring section 23 Switch

Claims

1. An electrohydrodynamic pump that generates a flow in a target fluid by applying a voltage to the target fluid having insulation, comprising a flow path forming member that defines a working flow path for applying a voltage to the target fluid and a pair of electrodes for applying an electric field to the working flow path, arranged in series, and a plurality of working parts for applying a voltage to the target fluid, a drive circuit for individually applying a voltage to the plurality of working parts, and is provided with, the plurality of working parts include those having different shapes of the working flow path between the pair of electrodes, an electrohydrodynamic pump.

2. The drive circuit individually applies or cuts off a constant voltage to the plurality of working parts, the electrohydrodynamic pump according to claim 1.

3. Each of the working parts has a casing that houses the flow path forming member, and the casing is constituted by a module separable from the casings of the other working parts, the electrohydrodynamic pump according to claim 1 or 2.

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