WO2019221121A1

WO2019221121A1 - Piezoelectric gas pump

Info

Publication number: WO2019221121A1
Application number: PCT/JP2019/019132
Authority: WO
Inventors: 哲也下田
Original assignee: 京セラ株式会社
Priority date: 2018-05-15
Filing date: 2019-05-14
Publication date: 2019-11-21
Also published as: JP6952400B2; JPWO2019221121A1

Abstract

This piezoelectric pump comprises a first casing (1) that includes a diaphragm (11) having a first opening part (111), a thin plate part (12) provided to a position of facing the diaphragm (11), and a frame body (13) connecting the diaphragm (11) and the thin plate part (12), and that has an internal space serving as a pump chamber. The piezoelectric pump also comprises a piezoelectric element (2) that has a through-hole (21) having an opening larger than the first opening part (111), and that is attached to the diaphragm (11) so that the first opening part (111) is positioned on the inner side of the through-hole (21) when seen from a direction perpendicular to the diaphragm (11). The piezoelectric pump also comprises an outer wall (3) that has discharge port (31) in a position near the first opening part (111), and that is provided so as to cover at least the diaphragm (11) and so that there is a fluid passage (4) between the outer wall (3) and the diaphragm (11).

Description

Piezoelectric gas pump

The present disclosure relates to a piezoelectric gas pump that generates a gas flow.

Conventionally, for example, a piezoelectric gas pump (flow generator) using a piezoelectric element as described in Japanese Patent Publication No. 64-2793 (hereinafter referred to as Patent Document 1) as a driving source is known.

The piezoelectric gas pump of the present disclosure includes an inner space that is a pump chamber, including a diaphragm having a first opening, a thin plate portion that faces the diaphragm, and a frame that connects the diaphragm and the thin plate portion. And a through hole having an opening larger than the first opening, and the first opening is positioned inside the through hole when viewed from a direction perpendicular to the diaphragm. A piezoelectric element attached to the diaphragm, and an outer wall having a discharge port at a position close to the first opening, covering at least the diaphragm, and having a fluid passage between the diaphragm and the diaphragm.

According to the piezoelectric gas pump of the present disclosure, a piezoelectric gas pump that is small in size and capable of increasing the fluid flow rate can be realized by superimposing the vibration of the thin plate portion on the vibration of the diaphragm.

It is a typical perspective view which shows an example of a piezoelectric gas pump. FIG. 2 is a schematic end view of a cross section taken along line AA of the piezoelectric gas pump shown in FIG. 1. It is a schematic perspective view of the 1st housing | casing and piezoelectric element which are shown in FIG. FIG. 3 is an enlarged end view showing an example of a form of a diaphragm located in an inner region of the piezoelectric element shown in FIG. 2. FIG. 5 is an enlarged end view showing another example of the form of the diaphragm located in the inner region of the piezoelectric element shown in FIG. 2. FIG. 5 is an enlarged end view showing another example of the form of the diaphragm located in the inner region of the piezoelectric element shown in FIG. 2. FIG. 5 is an enlarged end view showing another example of the form of the diaphragm located in the inner region of the piezoelectric element shown in FIG. 2. FIG. 5 is an enlarged end view showing another example of the form of the diaphragm located in the inner region of the piezoelectric element shown in FIG. 2. FIG. 5 is an enlarged end view showing another example of the form of the diaphragm located in the inner region of the piezoelectric element shown in FIG. 2. FIG. 5 is an enlarged end view showing another example of the form of the diaphragm located in the inner region of the piezoelectric element shown in FIG. 2.

Hereinafter, an example of a piezoelectric gas pump will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by an example of the disclosure shown below.

FIG. 1 is a schematic perspective view showing an example of the disclosure of a piezoelectric gas pump, FIG. 2 is a schematic end view of a section taken along line AA of the piezoelectric gas pump shown in FIG. 1, and FIG. 3 is shown in FIG. It is a schematic perspective view of a 1st housing | casing and a piezoelectric element.

1 and 2 includes a first housing 1 having an internal space serving as a pump chamber.

The first housing 1 includes a diaphragm 11 having a first opening 111, a thin plate portion 12 provided at a position facing the diaphragm 11, and a frame body 13 that connects the diaphragm 11 and the thin plate portion 12. Yes. In the example shown in the figure, the first housing 1 has a box shape with the diaphragm 11 as a top plate, the thin plate portion 12 as a bottom plate, and the frame body 13 as a side wall, and the first opening 111 is formed in the diaphragm 11. It is provided in the central part.

Inside the first housing 1, a space is formed by the diaphragm 11, the thin plate portion 12, and the frame body 13, and this space (internal space 10) becomes a pump chamber. The pump chamber here means a chamber that functions as a pump by repeatedly flowing gas in and out of the internal space 10 by the vibration of the diaphragm 11. As the gas (gas), oxygen-containing gas (air) can be used as appropriate.

As the diaphragm 11, the thin plate portion 12, and the frame 13 constituting the first housing 1, a metal member such as stainless steel (SUS), brass, and 42 alloy, or a resin member such as polybutylene terephthalate (PBT) and liquid crystal polymer is used. be able to.

The diaphragm 11 has a first opening 111, and gas flows into and out of the internal space 10 through the first opening 111. Here, the 1st opening part 11 may be the structure which has one hole, and the structure which has a some hole.

The thickness of the diaphragm 11 is, for example, 50 to 500 μm.

Further, when the diaphragm 11 has a disk shape and the first opening 11 has one circular hole, the diameter of the first opening 11 is, for example, 1 to 20 of the diameter of the outer peripheral shape of the diaphragm 11. % Length.

Further, when the diaphragm 11 has a disk shape and the first opening 111 has a plurality of circular holes, the number of the holes is, for example, 2 to 300, and the diameter of each hole is the outer circumference of the diaphragm 11. For example, the length is 0.02 to 10% of the diameter of the shape. When the 1st opening part 111 has a some hole, since the directivity of the discharge direction of the flowing-out gas can be suppressed, it becomes possible to blow a fluid in a wide range.

In addition, both the outer periphery shape of the diaphragm 11 and the shape of the 1st opening part 111 are not restricted circularly, A polygonal shape may be sufficient.

The thin plate portion 12 is provided at a position facing the diaphragm 11, and basically has the same outer peripheral shape as the outer peripheral shape of the diaphragm 11.

The frame 13 supports the diaphragm 11 and the thin plate portion 12 so as to provide a desired interval therebetween, and forms the first housing 1 together with the diaphragm 11 and the thin plate portion 12. Here, the frame body 13 shown in the drawing has a stepped shape having a convex portion 131 on the inner surface so as to protrude inward at a central portion in the height direction when viewed in cross section, and the convex portion 131 is The structure is sandwiched between the diaphragm 11 and the thin plate portion 12.

The frame body 13 is harder to deform than the diaphragm 11 and the thin plate portion 12. For example, when the frame body 13 has the same material as the diaphragm 11 and the thin plate portion 12, the frame body 13 is thicker than these. Here, when the frame 13 has a portion with a different thickness, such as the convex portion 131 on the inner surface, the thinnest portion of the frame 13 is thicker than the diaphragm 11 and the thin plate portion.

The frame body 13 is not limited to the shape having the convex portion 131 as shown in the figure, and may have a shape in which the thickness is constant along the height direction when viewed in a cross section, or a shape having a concave portion on the inner surface. May be.

Further, the piezoelectric gas pump has a through-hole 21 having an opening larger than the first opening 111, and the first opening 111 is positioned inside the through-hole 21 when viewed from a direction perpendicular to the diaphragm 11. The piezoelectric element 2 attached to the diaphragm 11 is provided. 2 is an end view, and not a plurality of the piezoelectric elements 2 shown in FIG. 2, but a single piezoelectric element 2 having an annular flat plate shape as shown in FIG.

The piezoelectric element 2 includes, for example, a piezoelectric body having a through-hole 21 and surface electrodes respectively provided on a pair of main surfaces opposed to the piezoelectric body.

As the piezoelectric body constituting the piezoelectric element 2, piezoelectric ceramics such as lead zirconate titanate-based, barium titanate-based, potassium niobate / sodium niobate-based, piezoelectric single crystals such as quartz and lithium tantalate can be used. As the surface electrode constituting the piezoelectric element 2, silver, nickel, copper, silver-palladium, or the like can be used.

Here, the fact that the piezoelectric element 2 has the through-hole 21 having an opening larger than that of the first opening 111 means that the cross-sectional area of the through-hole 21 is larger than the cross-sectional area of the first opening 111. Means that. The size of the through hole 21 is set so that the diaphragm 11 can obtain a displacement larger than the displacement of the piezoelectric element 2 in the inner region of the piezoelectric element 2 (the inner region of the through hole 21).

As shown in FIG. 1, the piezoelectric element 2 is connected to an external circuit through a wiring member 5, for example, and by driving the piezoelectric element 2, the diaphragm 11 can be vibrated and the piezoelectric gas pump can be driven.

The piezoelectric element 2 can take the following form as a pattern of surface electrodes provided on a pair of opposing main surfaces of a piezoelectric body.

The piezoelectric element 2 is a separately excited piezoelectric element in which surface electrodes provided on one main surface and the other main surface have one main surface electrode (a pair of main surface electrodes) extending in the surface direction on each surface. There may be.

The piezoelectric element 2 may be a so-called self-excited piezoelectric element in which a surface electrode provided on one main surface includes a main surface electrode and a sub surface electrode separated from the main surface electrode. By adopting such a configuration, for example, when using a plurality of piezoelectric gas pumps, the optimum driving frequency can be adjusted for each piezoelectric gas pump, so individual differences in the fluid flow rates of the piezoelectric gas pumps can be suppressed. In addition, it is possible to suppress changes in the fluid flow rate associated with environmental temperature changes such as −20 ° C. to + 80 ° C. In addition, if 42 alloy is used for the diaphragm 11, since the thermal expansion difference with the piezoelectric element 2 can be reduced, it is especially effective for suppression of the change of the fluid flow rate accompanying environmental temperature change.

Also, the piezoelectric gas pump has an outlet 311 at a position close to the first opening 111, and includes an outer wall 3 that covers at least the diaphragm 11 and has a fluid passage 4 between the diaphragm 11.

The outer wall 3 is provided so as to cover at least the diaphragm 11. In the example shown in the figure, a top plate portion 31 facing the diaphragm 11 from the outside of the first housing 1 and a frame body portion 32 are provided. As the top plate portion 31 and the frame body portion 32, a metal member such as stainless steel (SUS), brass, or 42 alloy, or a resin member such as polybutylene terephthalate (PBT) or liquid crystal polymer can be used.

The top plate 31 constituting the outer wall 3 has a discharge port 311 at a position close to the first opening 111. Here, the discharge port 311 means an opening through which gas (gas) flows out. The discharge port 311 has, for example, an opening area that is the same as or larger than that of the first opening 111.

The frame body portion 32 is joined to the outer peripheral portion of the top plate portion 31 to support the top plate portion 31. In the example shown in FIG. 2, the inner surface of the frame body portion 32 has a stepped shape, but may have a shape in which the thickness is constant along the height direction when viewed in cross section, or a shape having a recess on the inner surface. May be.

In the example shown in FIG. 1, an insertion port 321 through which the wiring member 5 is inserted is provided in a part of the frame body portion 32, and the wiring member 5 is taken out from the insertion port 321. There is no particular limitation.

The outer wall 3 (top plate portion 31) is provided so as to have a fluid passage 4 at least with the diaphragm 11. Here, the fluid passage 4 means a passage through which gas (gas) flows. The fluid passage 4 is formed by fixing the outer wall 3 so as to have a desired interval between the outer wall 3 (top plate portion 31) and the first housing 1 (diaphragm 11). For example, the inner dimension of the frame body portion 32 of the outer wall 3 is set to be larger than the outer dimension of the frame body 13 of the first housing 1, and a plurality of positions of the frame body 13 of the first housing 1 are set in the height direction. Projecting to the top plate portion 31, or projecting a plurality of portions of the frame body 13 of the first housing 1 in the radial direction (direction perpendicular to the height direction) to join the frame body portion 32. Thus, the fluid passage 4 can be formed.

In the example shown in FIGS. 1 and 2, the outer wall 3 includes a top plate portion 31 and a frame body portion 32, and the fluid passage 4 is also provided between the frame body 13 of the first housing 1 and the frame body portion 32 of the outer wall 3. However, the present invention is not limited to this configuration, and a configuration without the frame body portion 32 may be used.

In the example shown in FIGS. 1 and 2, the open end (lower end) between the frame 13 of the first housing 1 and the frame 32 of the outer wall 3 serves as a gas inlet. However, other forms are possible. For example, it may be configured to further include a bottom plate portion so that the outer wall 3 surrounds the entire first housing 1. In this case, a gas inlet is provided in the frame body portion 32 or the bottom plate portion.

The thin plate portion 12 vibrates with the vibration of the diaphragm 11. In order to vibrate in this way, the thin plate portion 12 may be more easily deformed than the diaphragm 11 and may be vibrated. For example, the elastic modulus of the thin plate portion 12 may be smaller than the elastic modulus of the diaphragm 11, and the thickness of the thin plate portion 12 may be thinner than the thickness of the diaphragm 11.

When the thickness of the thin plate portion 12 is made thinner than the thickness of the diaphragm 11, for example, the thickness of the thin plate portion 12 with respect to the thickness of the diaphragm 11 can be set to 30 to 80%. Specifically, when the thickness of the diaphragm 11 is 100 μm, the thickness of the thin plate portion 12 can be about 50 μm.

According to such a configuration, in addition to the displacement of the diaphragm 11 due to the displacement of the piezoelectric element 2, it is possible to induce a partial displacement of the diaphragm 11 located in the inner region of the piezoelectric element 2 (through hole 21), and further the diaphragm. The vibration of the thin plate portion 12 opposed to 11 can be superimposed. Therefore, it is possible to obtain a piezoelectric gas pump that is small in size and capable of increasing the fluid flow rate.

Here, as shown in FIGS. 4 and 5, the diaphragm 11 has at least a part of the region located inside the through-hole 21 when viewed from the direction perpendicular to the diaphragm 11, or on the thin plate portion 12 side. You may protrude toward the outer wall 3 (top plate part 31) side. In FIG. 4, a part of the diaphragm 11 located inside the through hole 21 when viewed from the direction perpendicular to the diaphragm 11 protrudes in a dome shape toward the outer wall 3 (top plate portion 31). Shows the configuration. FIG. 5 shows a configuration in which a part of the diaphragm 11 located inside the through hole 21 protrudes in a dome shape toward the thin plate portion 12 when viewed from a direction perpendicular to the diaphragm 11. Yes.

With such a configuration, the protruding portion of the diaphragm 11 is easily deformed due to the shape effect, so that the superimposed displacement of the diaphragm 11 located inside the through hole 21 of the piezoelectric element 2 can be further increased, and the fluid The flow rate can be further increased.

Further, as shown in FIGS. 6 to 10, the diaphragm 11 has a thickness at least a part of the region located inside the through hole 21 when viewed from the direction perpendicular to the diaphragm 11 overlaps the piezoelectric element 2. It may be different from the thickness of the region. 6 shows a configuration in which a part of the diaphragm 11 located inside the through hole 21 is thinned by a recess provided on the surface of the thin plate portion 12 when viewed from a direction perpendicular to the diaphragm 11. Is shown. FIG. 7 shows a configuration in which a part of the diaphragm 11 located inside the through-hole 21 when viewed from the direction perpendicular to the diaphragm 11 is thickened by the convex portion provided on the surface on the thin plate portion 12 side. Show. 8 shows that a part of the diaphragm 11 located inside the through hole 21 when viewed from the direction perpendicular to the diaphragm 11 is a surface on the thin plate portion 12 side and a surface on the outer wall 3 (top plate portion 31) side. The structure which is thin by the recessed part provided in both of is shown. In FIG. 9, a part of the diaphragm 11 located inside the through hole 21 when viewed from the direction perpendicular to the diaphragm 11 is thinned by a recess provided on the surface on the thin plate portion 12 side. However, the boundary between the dent and the other part as shown in FIG. 6 is not a stepped shape but an inclined configuration. FIG. 10 shows an annular shape in which a part of the diaphragm 11 located inside the through hole 21 when viewed from the direction perpendicular to the diaphragm 11 is provided on both surfaces of the outer wall 3 (top plate portion 31). A configuration in which the groove is thinner is shown.

With such a configuration, the rigidity of the diaphragm 11 located inside the through hole 21 of the piezoelectric element 2 is increased due to the decrease in rigidity due to the decrease in thickness, or the mass load effect (kinetic energy) due to the increase in thickness. Increase), the superimposed displacement of the diaphragm 11 positioned inside the through hole 21 of the piezoelectric element 2 can be further increased, and the fluid flow rate can be further increased.

Next, an example of a method for manufacturing a piezoelectric gas pump will be described.

First, raw materials such as lead zirconate titanate for forming the piezoelectric body of the piezoelectric element 2 are prepared by a ball mill or the like, and the obtained mixed raw material is calcined at 700 ° C. to 1200 ° C. The calcined synthetic raw material is pulverized with a ball mill or the like, and after adding a molding binder, granules are produced with a spray dryer.

Using the obtained granule, a molded body having a through hole is produced by press molding with a molding die having an axial pin near the center. A piezoelectric body obtained by degreasing and firing this molded body is processed into a desired shape by lapping or the like, and a surface electrode paste is printed and baked at 500 ° C. to 800 ° C. to form a surface electrode. Thereafter, a voltage of about 3 kV / mm is applied to obtain the piezoelectric element 2 having desired piezoelectric characteristics.

Next, for example, a thermosetting epoxy adhesive is printed on the diaphragm 11 having 42 alloy processed into a desired shape by punching or the like, and heated at 80 ° C. to 200 ° C. while the piezoelectric element 2 is brought into contact therewith. Thus, the diaphragm 11 having the piezoelectric element 2 is obtained.

Similarly, a thin plate portion 12 having SUS processed into a desired shape by punching or the like, and a frame body 13 having a convex portion 131 (step shape) on the inner surface formed by injection molding or the like are prepared. For example, an epoxy adhesive is applied to the step portions provided at the one end portion and the other end portion, and the diaphragm 11 is incorporated into the step portion at one end portion, and the thin plate portion 12 is incorporated into the step portion at the other end portion. The first housing 1 is obtained by heating and curing.

Next, in order to input an electric signal from the outside to the piezoelectric element 2, a wiring member 5, for example, a lead wire whose side surface is coated with a resin is prepared. Then, the wiring member 5 is electrically and mechanically joined to the surface electrode of the piezoelectric element 2 and the diaphragm 11 using a joining member such as solder.

Next, an epoxy-based adhesive is applied to the protrusion provided on the upper end in the height direction of the frame 13 constituting the first housing 1 or the protrusion provided on the outer surface, and the frame 32 constituting the outer wall 3 is applied. After joining to the inner surface, it is heated and cured.

The fluid passage 4 through which the fluid can move can be configured by appropriately setting the height of the protruding portion provided at the upper end in the height direction of the frame body 13 and the position of the receiving portion provided on the top plate portion 31. .

Next, for example, an epoxy-based adhesive is applied to the stepped portion provided at one end of the frame body portion 32, and the top plate portion 31 to which the first housing 1 is joined is assembled, heated, and cured, so that A piezoelectric gas pump is obtained.

DESCRIPTION OF SYMBOLS 1 1st housing | casing 11 Diaphragm 111 1st opening part 12 Thin plate part 13 Frame body 131 Convex part 2 Piezoelectric element 21 Through-hole 3 Outer wall 31 Top plate part 311 Discharge hole 32 Frame body part

Claims

A first housing having an inner space which is a pump chamber, including a diaphragm having a first opening, a thin plate portion positioned opposite to the diaphragm, and a frame connecting the diaphragm and the thin plate portion; ,
A piezoelectric device having a through hole having an opening larger than the first opening and attached to the diaphragm so that the first opening is located inside the through hole when viewed from a direction perpendicular to the diaphragm. Elements,
A piezoelectric gas pump comprising: an outer wall having a discharge port at a position close to the first opening, covering at least the diaphragm, and having a fluid passage between the diaphragm and the diaphragm.
The piezoelectric gas pump according to claim 1, wherein the thickness of the thin plate portion is thinner than the thickness of the diaphragm.
The diaphragm has at least a part of a region located inside the through hole when viewed from a direction perpendicular to the diaphragm, and protrudes toward the thin plate portion or the outer wall. The piezoelectric gas pump according to claim 2.
2. The diaphragm according to claim 1, wherein a thickness of at least a part of a region located inside the through hole when viewed from a direction perpendicular to the diaphragm is different from a thickness of a region overlapping the piezoelectric element. 2. The piezoelectric gas pump according to 2.
The piezoelectric element includes a piezoelectric body and surface electrodes respectively provided on a pair of opposing main surfaces of the piezoelectric body,
5. The self-excited piezoelectric element including the main surface electrode and the sub surface electrode separated from the main surface electrode, the surface electrode provided on one main surface. A piezoelectric gas pump according to claim 1.
The piezoelectric gas pump according to claim 1, wherein the first opening has a plurality of holes.