JP7447722B2 - electrohydrodynamic pump - Google Patents

Description

The present invention relates to electrohydrodynamic pumps.

2. Description of the Related Art Electrohydrodynamic effects are known in which a flow is generated in an insulating fluid by applying a voltage to the fluid. An electrohydrodynamic pump that discharges fluid by utilizing this electrohydrodynamic effect has been proposed. Electrohydrodynamic pumps do not require moving parts such as impellers, so they can be made smaller.

As a specific example, it is formed into a rod shape or a mesh shape, has one or more electrode pairs (positive electrode and negative electrode) to which a DC voltage is applied, and the negative electrode is arranged on the upstream side of the flow path so as to cross the flow path, An electrohydrodynamic pump in which a positive electrode is arranged in parallel with a negative electrode on the downstream side has been proposed (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2010-63342

Conventional electrohydrodynamic pumps have limited applications due to their low differential pressure (total head). Therefore, an object of the present invention is to provide an electrohydrodynamic pump with a large differential pressure.

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 target fluid having an insulating property, and the cross-sectional area of the target fluid increases toward the downstream side. It includes a flow path member having a decreasing working flow path, a negative electrode disposed upstream of the working flow path, and a positive electrode disposed downstream of the working flow path.

In the electrohydrodynamic pump, at least one of the negative electrode and the positive electrode may have a mesh shape.

In the electrohydrodynamic pump, the negative electrode may have a mesh shape, and the positive electrode may have a pipe shape or a needle shape.

In the electrohydrodynamic pump, the longitudinal direction of the positive electrode may be parallel to the flow direction of the target fluid.

The electrohydrodynamic pump defines a suction channel that supplies the target fluid to the working channel, and includes a suction holding member that holds the negative electrode, and a discharge that guides the target fluid flowing out from the working channel. The device may further include a discharge holding member that defines a flow path and holds the positive electrode.

According to the present invention, an electrohydrodynamic pump with a large differential pressure can be provided.

FIG. 1 is a sectional view showing an electrohydrodynamic pump according to a first embodiment of the present invention. FIG. 3 is a sectional view showing an electrohydrodynamic pump according to a second embodiment of the present invention. FIG. 3 is a sectional view showing an electrohydrodynamic pump according to a third embodiment of the present invention. It is a sectional view showing an electrohydrodynamic pump according to a fourth embodiment of the present invention. 3 is a graph showing the relationship between applied voltage and differential pressure in an embodiment of the electrohydrodynamic pump according to the present invention.

Hereinafter, each embodiment of the electrohydrodynamic pump according to the present invention will be described with reference to the drawings. In addition, in the following description, the same reference numerals may be attached to the same components of the embodiment described later as those of the previously described embodiment, and the redundant explanation may be omitted.

<First embodiment>
FIG. 1 is a sectional view of an electrohydrodynamic pump 1 according to a first embodiment of the present invention. The electrohydrodynamic pump 1 is a pump that applies a voltage to an insulating target fluid to generate a flow in the target fluid. In FIG. 1, the left and right arrows of the electrohydrodynamic pump 1 indicate the flow direction of the target fluid. The electrohydrodynamic pump 1 of this embodiment includes a flow path member 10, a negative electrode 20, a positive electrode 30, a suction holding member 40, a discharge holding member 50, a suction cap 60, and a discharge cap 70.

The flow path member 10 includes a partition part 12 having a working flow path 11 through which the target fluid flows, and a cylindrical part provided on the outside of the partition part 12 and housing a negative electrode 20, a positive electrode 30, a suction holding member 40, and a discharge holding member 50. It has a housing part 13.

The partition part 12 seals the inside of the housing part 13 and separates the upstream space from the downstream space in order to define the working flow path 11 of a desired shape and limit the flow path of the target fluid only to the working flow path 11. It can be formed so as to isolate it from the side space.

The cross-sectional area of the working channel 11 decreases toward the downstream side. Thereby, the pressure of the target fluid within the working channel 11 can be increased. In the electrohydrodynamic pump 1 of this embodiment, the working flow path 11 is formed in a conical shape.

The lower limit of the ratio of the diameter of the inlet to the diameter of the outlet of the working channel 11 can be, for example, 5 or more and 20 or less, preferably 8 or more and 15 or less. This allows the pressure of the target fluid to be sufficiently increased.

The ratio of the diameter of the working channel 11 to the channel length (distance between the inlet and the outlet, and therefore the distance between the negative electrode 20 and the positive electrode 30) can be, for example, 1 or more and 10 or less, preferably 2 or more and 8 or less. . Thereby, the pressure of the target fluid can be increased with a relatively small channel length. In particular, by reducing the length of the diameter of the working flow path 11, the differential pressure of the electrohydrodynamic pump 1 can be further increased.

In order to hold the suction holding member 40 on the upstream side of the partition wall portion 12, the housing portion 13 may have a suction mounting structure 14 such as an internal thread into which the suction holding member 40 is screwed, for example. Similarly, the housing section 13 may have a discharge mounting structure 15 for holding the discharge holding member 50 on the downstream side of the partition wall section 12 .

Further, the housing part 13 is provided with a wiring part 16 that allows connection of a wiring L for applying voltage from an external battery B to the negative electrode 20 and the positive electrode 30 arranged inside the housing part 13 without leaking the target fluid. ing. For example, the wiring part 16 has a sealing structure that seals the gap between the opening from which the wiring L is drawn out and the wiring L, and is airtightly attached to the housing part 13, with the wiring L connected to the inside and the wiring from the battery B to the outside. It can have a terminal structure for connecting a power supply line.

The negative electrode 20 has a shape having openings or gaps through which the target fluid can pass, such as a mesh shape or a lattice shape, and preferably a mesh shape that has a large contact area with the target fluid. Specifically, the negative electrode 20 can be formed of a metal wire mesh, preferably a stainless steel wire mesh with relatively high strength.

It is preferable that the negative electrode 20 is disposed to cover the inlet of the working channel 11 so that it can efficiently contact the target fluid flowing into the working channel 11 . Further, it is preferable that the negative electrode 20 is arranged substantially perpendicular to the flow direction of the target fluid so that the distance from the positive electrode 30 is constant.

The aperture ratio of the negative electrode 20 is preferably 15% or more and 80% or less, more preferably 20% or more and 65% or less, and even more preferably 25% or more and 50% or less. Thereby, it is possible to secure a contact area between the negative electrode 20 and the target fluid while suppressing an increase in flow path resistance due to the negative electrode 20, and to apply a pressure difference to the target fluid.

The negative electrode 20 may partially have large openings or gaps in order to facilitate the flow of the target fluid. As a specific example, the negative electrode 20 may be made of a mesh-like material with openings formed therein.

Like the negative electrode 20, the positive electrode 30 is formed in a mesh shape and can be arranged to cover the outlet of the working channel 11. Since the positive electrode 30 covers the outlet of the working channel 11, which has a small opening area, it is preferable that the positive electrode 30 has a uniform mesh shape in order to ensure a contact area with the target fluid.

The suction holding member 40 defines a suction flow path 41 that supplies the target fluid to the working flow path 11 and holds the negative electrode 20 . Specifically, the suction holding member 40 includes a suction passage 41 penetrating through the center, a fixing structure 42 provided at the outer circumference for fixing to the passage member 10, and a fixing structure 42 provided at the tip and connected to the negative electrode 20. The structure may include a holding structure 43 for holding the wiring L, and a wiring hole 44 in which the wiring L is placed.

The flow area of the suction flow path 41 is greater than or equal to the opening area of the inlet of the working flow path 11 . As a specific example, the suction channel 41 is formed coaxially with the working channel 11 and has a constant cross-sectional shape that is equal to the opening of the inlet of the working channel 11 .

The fixing structure 42 can be, for example, an external thread that is threaded into an internal thread formed on the inner circumferential surface of the housing portion 13 of the flow path member 10. Further, the fixing structure 42 may be a bolt hole or the like into which a bolt that is threaded into a screw hole formed in the partition wall 12 of the channel member 10 is inserted.

The holding structure 43 can be designed as appropriate depending on the shape of the negative electrode 20 and the like. As a specific example, the holding structure 43 is a small diameter portion that allows the outer circumference of the negative electrode 20 that is in contact with the distal end surface of the suction holding member 40 to be bent upstream along the outer circumference of the suction holding member 40. be able to. In such a configuration, the negative electrode 20 may be fixed to the suction holding member 40 by tightening the outer peripheral portion of the bent negative electrode 20 with a band or the like. Further, the holding structure 43 may have a structure in which the negative electrode 20 is bonded to the distal end surface of the suction holding member 40 using an adhesive, or, for example, a structure in which the negative electrode 20 is fixed to the distal end surface of the suction holding member 40 using a flange, a cap, etc. may be taken as Although the holding structure 43 may be omitted so that the negative electrode 20 can be directly positioned and fixed to the partition wall 12, the suction holding member 40 having the holding structure 43 can easily and reliably hold the negative electrode 20 in the working channel. 11 entrances.

The discharge holding member 50 defines a discharge flow path 51 that guides the target fluid flowing out from the working flow path 11 and holds the positive electrode 30 so as to form a pair with the suction holding member 40 . Specifically, like the suction holding member 40, the discharge holding member 50 includes a discharge flow path 51 formed by penetrating the central portion, and a fixing structure provided on the outer periphery for fixing to the flow path member 10. 52, a holding structure 53 provided at the tip for holding the positive electrode 30, and a wiring hole 54 in which the wiring L is disposed.

The suction cap 60 is configured to close the upstream end of the flow path member 10 and connect a pipe (not shown) for supplying the target fluid. The structure for fixing the suction cap 60 to the flow path member 10 can be appropriately selected based on common technical knowledge, but in this embodiment, it is a flange-like structure. Further, the structure for connecting the piping of the suction cap 60 can be appropriately selected based on common technical knowledge, but in this embodiment, it is a female thread for a pipe.

The discharge cap 70 is configured as a pair with the suction cap 60 to close the downstream end of the flow path member 10 and to be connected to a pipe (not shown) for discharging the target fluid. The structure of the discharge cap 70 can also be appropriately selected based on common technical knowledge.

In the electrohydrodynamic pump 1 having the above configuration, the negative electrode 20 applies an electric charge to the target fluid, and the positive electrode 30 attracts the charged target fluid by electrostatic force to recover the electric charge from the target fluid. Thereby, the target fluid moves in the working channel 11 from the upstream side to the downstream side. At this time, since the cross-sectional area of the working channel 11 decreases toward the downstream side, the differential pressure can be increased.

<Second embodiment>
FIG. 2 is a sectional view of an electrohydrodynamic pump 1A according to a second embodiment of the present invention. The electrohydrodynamic pump 1A of this embodiment includes a plurality of sets of channel members 10, a negative electrode 20, a positive electrode 30, a suction holding member 40, and a discharge holding member 50, and one set of a suction cap 60 and a discharge cap 70. Be prepared.

The electrohydrodynamic pump 1A of FIG. 2 has a plurality of main parts of the electrohydrodynamic pump 1 of FIG. 1, except for the suction cap 60 and the discharge cap 70, arranged in series. It has multiple stages. With this configuration, the electrohydrodynamic pump 1A of this embodiment can obtain a higher differential pressure than the electrohydrodynamic pump 1 of FIG. 1.

<Third embodiment>
FIG. 3 is a sectional view of an electrohydrodynamic pump 1B according to a third embodiment of the present invention. The electrohydrodynamic pump 1B of this embodiment includes a flow path member 10B, a negative electrode 20, a positive electrode 30, a suction holding member 40, a discharge holding member 50, a suction cap 60, and a discharge cap 70.

The flow path member 10B includes a partition wall portion 12B having a working flow path 11B through which the target fluid flows, and a cylindrical housing portion 13 provided on the outside of the partition wall portion 12B and housing the suction holding member 40 and the discharge holding member 50. have

The working channel 11B is formed in a bellmouth shape in which the inclination angle of the outer wall with respect to the flow direction of the target fluid (the central axis of the working channel 11B) decreases toward the downstream. This reduces the flow path resistance of the target fluid in the working flow path 11B, so it is possible to suppress a drop in the differential pressure when the flow rate of the target fluid is increased.

<Fourth embodiment>
FIG. 4 is a sectional view of an electrohydrodynamic pump 1C according to a fourth embodiment of the present invention. The electrohydrodynamic pump 1C of this embodiment includes a flow path member 10C, a negative electrode 20, a positive electrode 30C, a suction holding member 40, a discharge holding member 50C, a suction cap 60, and a discharge cap 70.

The flow path member 10C includes a partition wall portion 12C that has a working flow path 11 through which the target fluid flows, a discharge flow path 17 continuous to the downstream side of the working flow path 11, and a discharge mounting structure 15C that holds the discharge holding member 50C. and a cylindrical housing portion 13C provided outside the partition wall portion 12C.

The positive electrode 30C is formed into a needle shape and is held on the central axis of the discharge flow path 17 so that its longitudinal direction extends parallel to the flow direction of the target fluid. The target fluid flows in the space between the outer wall of the discharge flow path 17 and the outer peripheral surface of the positive electrode 30C. As a result, the contact area of the positive electrode 30C with the target fluid can be increased, so that the charge applied by the negative electrode 20 can be recovered more reliably. As a result, it is possible to prevent a force from acting on the target fluid that has passed through the positive electrode 30 without being able to recover the charge to the upstream side, thereby increasing the differential pressure generated by the electrohydrodynamic pump 1C. In addition, in order to increase the contact area with the target fluid, the positive electrode 30C may be formed in the shape of a hollow pipe, and a flow path for the target fluid may also be formed inside the positive electrode 30C.

The discharge holding member 50C includes a holding part 55 that holds the positive electrode 30C, a mounting part 56 that engages with the discharge mounting structure 15C of the housing part 13C, and a connecting part 57 that extends radially to connect the holding part 55 and the mounting part 56. and can have.

Although each preferred embodiment of the electrohydrodynamic pump of the present invention has been described above, the present invention is not limited to the above-described embodiments, and can be modified as appropriate.

For example, in the electrohydrodynamic pump of the present invention, components other than the channel member may have a housing that accommodates the other member, or may not have a housing that accommodates the other member, and the channel member, The discharge holding member and the discharge holding member may be airtightly connected to each other.

Furthermore, in the electrohydrodynamic pump of the present invention, the suction channel may also be defined by the channel member. In this case, the negative electrode is held within the suction channel.

Further, in the electrohydrodynamic pump of the present invention, the working channel may have a shape in which the inclination angle of the outer wall with respect to the flow direction increases toward the downstream side, and the inclination angle of the outer wall with respect to the flow direction increases from the central part to the upstream part. It may have a shape that decreases toward both the side and the downstream side.

Furthermore, in the electrohydrodynamic pump of the present invention, the negative electrode is placed on the upstream side of the working flow path, and the positive electrode is placed on the downstream side of the working flow path, but this is not intended to be the positional relationship between the negative electrode and the positive electrode. However, it is not required that the negative electrode be disposed upstream of the working flow path and the positive electrode disposed downstream of the working flow path. Therefore, the negative electrode and the positive electrode in the electrohydrodynamic pump of the present invention may be placed in the middle of the working flow path defined by the flow path member.

EXAMPLES The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to these Examples.

In accordance with the above-described embodiment, prototype examples 1 to 3 of electrohydrodynamic pumps having different shapes of working channels, negative electrodes, and positive electrodes were created, and a voltage of 10 kV was applied using 3M's "Novec" as the target fluid. The differential pressure caused by this was measured.

The electrohydrodynamic pump of Prototype Example 1 had a cylindrical working flow path with a constant cross-sectional area, and used stainless steel wire mesh as the negative and positive electrodes. The diameter of the working channel was 20 mm, and the length of the working channel was 5 mm. The mesh size of the negative electrode and positive electrode was #200 (wire diameter 0.05 mm, aperture ratio 36.8%).

In the electrohydrodynamic pump of Prototype Example 2, the working flow path had a truncated conical shape with a cross-sectional area smaller toward the downstream side, and stainless steel wire mesh was used as the negative and positive electrodes. The diameter of the inlet of the working channel was 25 mm, the diameter of the outlet of the working channel was 2 mm, and the length of the working channel was 5 mm. The mesh size of the negative electrode and positive electrode was #635 (wire diameter 0.02 mm, aperture ratio 25%).

In the electrohydrodynamic pump of Prototype Example 3, the working channel had a truncated conical shape with a cross-sectional area smaller toward the downstream side, stainless steel wire mesh was used as the negative electrode and the positive electrode, and an opening was formed in the negative electrode. The diameter of the inlet of the working channel was 25 mm, the diameter of the outlet of the working channel was 2 mm, and the length of the working channel was 5 mm. The mesh size of the negative electrode and the positive electrode was #250 (wire diameter 0.03 mm, aperture ratio 49.7%). The diameter of the opening of the negative electrode was 5 mm.

The method for measuring differential pressure is to supply the target fluid from a transparent water tank to an electrohydrodynamic pump, use a transparent tube as the discharge piping of the electrohydrodynamic pump, and measure the height of the liquid level in the water tank and the liquid level in the discharge piping. The differential pressure generated by the electrohydrodynamic pump was calculated by measuring the height difference between In other words, in this test, we measured the differential pressure of the electrohydrodynamic pump when the flow rate was zero.

As a result, the differential pressure of the electrohydrodynamic pump of Prototype Example 1 was 391 MPa, the differential pressure of the electrohydrodynamic pump of Prototype Example 2 was 1615 MPa, and the differential pressure of the electrohydrodynamic pump of Prototype Example 3 was 1780 MPa.

From these results, it was confirmed that the differential pressure of the electrohydrodynamic pump could be greatly improved by forming the working flow path into a truncated cone shape with a cross-sectional area smaller toward the downstream side.

Further, FIG. 5 shows the relationship between the differential pressure of the electrohydrodynamic pump of Prototype Example 3 and the applied voltage. As shown in the figure, the differential pressure increases linearly as the applied voltage increases, so it can be seen that this electrohydrodynamic pump is suitable for controlling the flow of a target fluid.

1, 1A, 1B, 1C Electrohydrodynamic pump 10, 10B, 10C Channel member 11, 11B Working channel 12, 12B, 12C Partition wall section 13, 13C Housing section 14 Suction mounting structure 15, 15C Discharge mounting structure 16 Wiring section 17 Discharge passage 20 Negative electrode 30 Positive electrode 40 Suction holding member 41 Suction passage 42 Fixed structure 43 Holding structure 44 Wiring hole 50, 50C Discharge holding member 51 Discharge passage 52 Fixed structure 53 Holding structure 54 Wiring hole 55 Holding part 56 Mounting part 57 Connection part 60 Suction cap 70 Discharge cap B Battery L Wiring

Claims (5)

An electrohydrodynamic pump that generates a flow in a target fluid by applying a voltage to the target fluid having insulating properties,
a flow path member having a working flow path whose cross-sectional area decreases toward the downstream side;
a negative electrode disposed on the upstream side of the working flow path;
a positive electrode disposed on the downstream side of the working channel;
Equipped with
The working flow path has a reduced cross-sectional area between the negative electrode and the positive electrode. The electrohydrodynamic pump according to claim 1, wherein at least one of the negative electrode and the positive electrode has a mesh shape. The electrohydrodynamic pump according to claim 1, wherein the negative electrode has a mesh shape and the positive electrode has a pipe shape or a needle shape. The electrohydrodynamic pump according to claim 3, wherein the longitudinal direction of the positive electrode is parallel to the flow direction of the target fluid. a suction holding member that defines a suction flow path for supplying the target fluid to the working flow path and holds the negative electrode;
a discharge holding member that defines a discharge flow path that guides the target fluid flowing out from the working flow path and holds the positive electrode;
The electrohydrodynamic pump according to any one of claims 1 to 4, further comprising:

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