WO2013187270A1

WO2013187270A1 - Blower

Info

Publication number: WO2013187270A1
Application number: PCT/JP2013/065320
Authority: WO
Inventors: 若林祐貴; 金井俊吾; 兼田陽子
Original assignee: 株式会社村田製作所
Priority date: 2012-06-11
Filing date: 2013-06-03
Publication date: 2013-12-19

Abstract

A piezoelectric blower (100) is provided with an external case (17), a top plate (37), a side plate (38), an oscillating plate (39), a piezoelectric element (40), and a cap (42). The top plate (37), the side plate (38), and the oscillating plate (39) constitute a blower chamber (36). A through-hole (45) is provided in the top plate (37). A plurality of projections (138) projecting toward the center of the blower chamber (36) are formed on the inside surfaces of the side plates (38) constituting side surfaces of the blower chamber (36). When an alternating driving voltage is applied to the piezoelectric elements (40), the oscillating plate (39) oscillates by bending and the top plate (37) oscillates by bending in concert with the bending oscillation of the oscillating plate (39). Consequently, the volume of the blower chamber (36) changes in a cyclical manner.

Description

Blower

The present invention relates to a blower that transports gas.

Patent Document 1 discloses a microblower for cooling the heat generated inside a portable electronic device or supplying oxygen necessary for power generation by a fuel cell.

FIG. 10 is a cross-sectional view of a micro blower 900 according to Patent Document 1. The micro blower 900 includes an inner case 2, an elastic metal plate 5 A, a piezoelectric element 5 B, an outer case 3 that covers the outer side of the inner case 2, and a lid member 9. The inner case 2 is elastically supported with respect to the outer case 3 by a plurality of connecting portions 4.

The inner case 2 has a U-shaped cross section with an opening at the bottom, and an elastic metal plate 5A is joined so as to close the opening. Thereby, the inner case 2 forms the blower chamber 6 together with the elastic metal plate 5A. The inner case 2 is formed with an opening 8 that communicates the inside and outside of the blower chamber 6. A piezoelectric element 5B is attached to the main surface of the elastic metal plate 5A opposite to the blower chamber 6.

A discharge port 3 A is formed in the region of the outer case 3 facing the opening 8. The outer case 3 has a lid member 9 so as to accommodate the inner case 2. A suction port 9 A is formed in the center of the lid member 9. An air inflow passage 7 is formed between the outer case 3 and the joined body of the inner case 2, the elastic metal plate 5A and the piezoelectric element 5B.

In the above configuration, when an AC drive voltage is applied to the piezoelectric element 5B, the piezoelectric element 5B expands and contracts, and the elastic metal plate 5A bends and vibrates due to the expansion and contraction of the piezoelectric element 5B. And the volume of the blower chamber 6 changes periodically by the bending deformation of the elastic metal plate 5A.

More specifically, when an AC drive voltage is applied to the piezoelectric element 5B and the elastic metal plate 5A is bent toward the piezoelectric element 5B, the volume of the blower chamber 6 increases. Accordingly, air outside the micro blower 900 is sucked into the blower chamber 6 through the suction port 9 A, the inflow passage 7, and the opening 8. At this time, although there is no outflow of air from the blower chamber 6, the inertial force of the air flow from the discharge port 3 A to the outside of the microblower 900 works.

Next, when an AC drive voltage is applied to the piezoelectric element 5B and the elastic metal plate 5A is bent toward the blower chamber 6, the volume of the blower chamber 6 decreases. Accordingly, the air in the blower chamber 6 is discharged from the discharge port 3 A through the opening 8 and the inflow passage 7.

At this time, the air flow discharged from the blower chamber 6 is discharged from the discharge port 3A while drawing the air outside the micro blower 900 through the suction port 9A and the inflow passage 7. Therefore, the flow rate of the air discharged from the discharge port 3A increases by the flow rate of the drawn air.

As described above, in the micro blower 900, the discharge flow rate per power consumption is increased.

JP 2011-27079 A

However, in recent years, electronic devices equipped with the microblower having the structure shown in FIG. 10 have a tendency to reduce power consumption. Therefore, there is a demand for a micro blower that further reduces power consumption without reducing the discharge flow rate.

Therefore, an object of the present invention is to provide a blower that can greatly increase the discharge flow rate per power consumption and can secure a necessary discharge flow rate with low power consumption.

The blower of the present invention has the following configuration in order to solve the above problems.

(1) a vibration plate that flexibly vibrates;
A driver that is provided on at least one main surface of the diaphragm and vibrates the diaphragm;
A first housing that forms a blower chamber together with the diaphragm,
The first housing has a top plate portion facing the diaphragm, and a side wall portion connecting the diaphragm and the top plate portion,
The top plate portion is formed with a vent hole that communicates the inside and outside of the blower chamber,
The side wall is formed with a protrusion that protrudes toward the center of the blower chamber.

In this configuration, when a driving voltage is applied to the driving body, the driving body causes the diaphragm to bend and vibrate. The volume of the blower chamber is periodically changed by the deformation of the diaphragm, and the gas in the blower chamber is discharged from the vent hole.

Comparing the blower having this configuration with the conventional microblower having the structure shown in FIG. 10, the difference between the volume V ₁ when the blower chamber is fully expanded and the volume V ₂ when the blower chamber is maximum contracted (V ₁ − V ₂ ) is the same. However, since provided with projections in the blower of this configuration, the volume V ₁ of the time of maximum expansion of the blower chamber is reduced than the conventional micro-blower. That is, by providing the protrusion, the volume change rate (V ₁ −V ₂ ) / V ₁ of the blower chamber is increased.

Thereby, the flow rate of air per displacement of the diaphragm discharged from the inside of the blower chamber to the outside of the blower chamber through the vent hole is increased as compared with the conventional micro blower. Here, the displacement amount of the diaphragm is determined by the power consumption to the driving body.

Further, in this configuration, while the blower chamber changes from the maximum expanded state to the maximum contracted state, the gap between the projection and the diaphragm in the blower chamber becomes narrower than before, so the gas between the projection and the diaphragm in the blower chamber Moves to the center of the blower chamber and the pressure in the center of the blower chamber increases. For this reason, while the blower chamber changes from the maximum expanded state to the maximum contracted state, the rate at which the gas in the blower chamber is discharged from the vent hole to the outside of the blower chamber becomes larger than that of the conventional micro blower.

Therefore, according to this configuration, the discharge flow rate per power consumption can be greatly increased, and the necessary discharge flow rate can be ensured with low power consumption.

(2) It is preferable that the protrusion is formed in the blower chamber in a range that does not contact the vibration plate that is flexibly vibrated.

In this configuration, since the protrusion does not come into contact with the diaphragm that vibrates and vibrates, it is possible to prevent the vibration of the diaphragm from being inhibited by the protrusion.

(3) The diaphragm bends and vibrates in an odd-order vibration mode equal to or higher than a third-order mode that forms a plurality of vibration antinodes by the driver,
The protrusion is formed to have a length not more than a length from a position of the vibration plate in contact with a side surface of the blower chamber to a vibration node having the shortest distance among vibration nodes formed by bending vibration of the vibration plate. It is preferable.

In this configuration, since the protrusion does not come into contact with a region where the vibration plate is largely displaced (the center portion of the vibration plate) among vibration plates that flexurally vibrate in an odd-order vibration mode, vibration of the vibration plate is inhibited by the protrusion. Can be prevented.

(4) It is preferable that the top plate portion bends and vibrates with bending vibration of the diaphragm.

In this configuration, since the top plate portion vibrates with the vibration of the diaphragm, the vibration amplitude can be substantially increased, and thereby the discharge pressure and the discharge flow rate can be increased.

(5) A second casing in which the first casing is covered with an interval to form a ventilation path between the first casing and a discharge port is formed in a region facing the vent hole. And a body.

In this configuration, the airflow flowing out from the blower chamber through the vent hole is discharged from the discharge port while drawing the gas existing outside the blower through the vent passage. Thereby, the discharge flow rate of the blower is increased by the flow rate of the drawn gas.

According to the present invention, the discharge flow rate per power consumption can be greatly increased, and the necessary discharge flow rate can be ensured with low power consumption.

1 is an external perspective view of a piezoelectric blower 100 according to a first embodiment of the present invention. It is a disassembled perspective view of the piezoelectric blower 100 shown in FIG. FIG. 2 is a sectional view taken along line SS of the piezoelectric blower 100 shown in FIG. FIG. 4 is a cross-sectional view taken along line SS of the piezoelectric blower 100 when the piezoelectric blower 100 shown in FIG. 1 is operated in the primary mode. 4A is a diagram when the volume of the blower chamber is increased, and FIG. 4B is a diagram when the volume of the blower chamber is decreased. FIG. 5 is a sectional view taken along the line SS of the piezoelectric blower 100 when the piezoelectric blower 100 shown in FIG. 1 is operated in the tertiary mode. 5A is a diagram when the volume of the blower chamber is increased, and FIG. 5B is a diagram when the volume of the blower chamber is decreased. It is sectional drawing of the piezoelectric blower 200 which concerns on 2nd Embodiment of this invention. FIG. 7 is a cross-sectional view of the piezoelectric blower 200 when the piezoelectric blower 200 shown in FIG. 6 is operated in the primary mode. 7A is a view when the volume of the blower chamber is increased, and FIG. 7B is a view when the volume of the blower chamber is decreased. It is sectional drawing of the piezoelectric blower 300 which concerns on 3rd Embodiment of this invention. FIG. 9 is a cross-sectional view of the piezoelectric blower 300 when the piezoelectric blower 300 shown in FIG. 8 is operated in the primary mode. FIG. 9A is a diagram when the volume of the blower chamber is increased, and FIG. 9B is a diagram when the volume of the blower chamber is decreased. It is sectional drawing of the micro blower 900 which concerns on patent document 1. FIG.

<< First Embodiment of the Invention >>
Hereinafter, the piezoelectric blower 100 according to the first embodiment of the present invention will be described.

FIG. 1 is an external perspective view of the piezoelectric blower 100 according to the first embodiment of the present invention. FIG. 2 is an exploded perspective view of the piezoelectric blower 100 shown in FIG. FIG. 3 is a cross-sectional view taken along line SS of the piezoelectric blower 100 shown in FIG.

The piezoelectric blower 100 includes an outer casing 17, a top plate 37, a side plate 38, a vibration plate 39, a piezoelectric element 40, and a cap 42 in order from the top, and has a structure in which these are stacked in order. The top plate 37, the side plate 38, and the diaphragm 39 constitute a blower chamber 36. The piezoelectric blower 100 has dimensions of a width of 20 mm × a length of 20 mm × a height of 1.85 mm in a region other than the nozzle 18.

The joined body of the top plate 37 and the side plate 38 corresponds to the “first casing” of the present invention, and the outer casing 17 corresponds to the “second casing” of the present invention. The top plate 37 corresponds to the “top plate portion” of the present invention, and the side plate 38 corresponds to the “side wall portion” of the present invention. The piezoelectric element 40 corresponds to the “driving body” of the present invention.

The outer casing 17 has a nozzle 18 formed around a discharge port 24 through which air is discharged. The nozzle 18 has a size of an outer diameter of 2.0 mm × an inner shape (that is, a discharge port 24) of a diameter of 0.8 mm × a height of 1.6 mm. Screw holes 56A to 56D are formed in the square of the outer casing 17.

The outer casing 17 is formed in a U-shaped cross-section with an open bottom, and the outer casing 17 houses the top plate 37 of the blower chamber 36, the side plate 38 of the blower chamber 36, the vibration plate 39 and the piezoelectric element 40. To do. The outer casing 17 is made of, for example, resin.

The top plate 37 of the blower chamber 36 has a disk shape and is made of, for example, metal. The top plate 37 is formed with a central portion 61, a key-like protruding portion 62 that protrudes horizontally from the central portion 61 and contacts the inner wall of the outer casing 17, and an external terminal 63 for connecting to an external circuit. Has been.

Further, the central portion 61 of the top plate 37 is provided with a vent hole 45 that allows the inside and outside of the blower chamber 36 to communicate with each other. The vent hole 45 is formed at a position facing the discharge port 24 of the outer casing 17. The top plate 37 is joined to the upper surface of the side plate 38.

The side plate 38 of the blower chamber 36 has an annular shape, and is made of, for example, metal. The side plate 38 is joined to the upper surface of the diaphragm 39. Therefore, the thickness of the side plate 38 is the height of the blower chamber 36.

Here, a plurality of protrusions 138 projecting toward the center of the blower chamber 36 are formed on the inner surface of the side plate 38 constituting the side surface of the blower chamber 36. The shape of the protrusion 138 is a convex curved surface.

As shown in FIGS. 4A and 4B to be described later, the protrusion 138 does not contact the diaphragm 39 and the top plate 37 that flexurally vibrate at the frequency of the primary mode (hereinafter, fundamental wave) as shown in FIGS. Is formed.

Further, as shown in FIGS. 5A and 5B described later, the protrusion 138 is a region in which the displacement is large in the vibration plate 39 and the top plate 37 that flexurally vibrate at a third-order mode frequency (third harmonic wave). That is, on the side surface of the blower chamber 36 among the vibration nodes formed by the bending vibration of the vibration plate 39 so as not to contact the region from the center of the vibration plate 39 and the top plate 37 to the vibration node with the shortest distance. It is formed below the length from the position of the diaphragm 39 in contact with the node F of the vibration with the shortest distance.

The diaphragm 39 has a disk shape and is made of, for example, metal. The diaphragm 39 constitutes the bottom surface of the blower chamber 36.

The piezoelectric element 40 has a disk shape and is made of, for example, lead zirconate titanate ceramic. The piezoelectric element 40 is bonded to the main surface of the diaphragm 39 opposite to the blower chamber 36, and bends according to the applied AC voltage.

The joined body of the top plate 37, the side plate 38, the vibration plate 39, and the piezoelectric element 40 is elastically supported with respect to the outer casing 17 by the four projecting portions 62 provided on the top plate 37. Yes.

The electrode conduction plate 70 includes an internal terminal 73 for connection to the piezoelectric element 40 and an external terminal 72 for connection to an external circuit. The tip of the internal terminal 73 is soldered to the flat surface of the piezoelectric element 40. By setting the soldering position to a position corresponding to the bending vibration node of the piezoelectric element 40, the vibration of the internal terminal 73 can be further suppressed.

A disc-shaped suction port 53 is formed in the cap 42. The diameter of the suction port 53 is longer than the diameter of the piezoelectric element 40. Further, the cap 42 has notches 55A to 55D formed at positions corresponding to the screw holes 56A to 56D of the outer casing 17.

The cap 42 has a protruding portion 52 that protrudes toward the top plate 37 on the outer peripheral edge. The cap 42 holds the outer casing 17 with the protruding portion 52, and houses the top plate 37 of the blower chamber 36, the side plate 38 of the blower chamber 36, the vibration plate 39, and the piezoelectric element 40 together with the outer casing 17. The cap 42 is made of, for example, resin.

As shown in FIG. 3, a ventilation path 31 is formed between the joined body of the top plate 37, the side plate 38, the vibration plate 39 and the piezoelectric element 40 and the outer casing 17 and the cap 42.

Hereinafter, the flow of air when the piezoelectric blower 100 operates will be described.

4A and 4B are cross-sectional views taken along the line SS of the piezoelectric blower 100 when the piezoelectric blower 100 shown in FIG. 1 is operated at a primary mode frequency (fundamental wave). Here, the arrows in the figure indicate the flow of air.

In the state shown in FIG. 3, when an AC drive voltage having a primary mode frequency (fundamental wave) is applied from the

external terminals

63 and 72 to the piezoelectric element 40, the diaphragm 39 bends and vibrates concentrically. At the same time, the top plate 37 is flexibly vibrated concentrically with the bending vibration of the vibration plate 39 (in this embodiment, the vibration phase is delayed by 180 °) due to the pressure fluctuation of the blower chamber 36 accompanying the bending vibration of the vibration plate 39. To do. Accordingly, as shown in FIGS. 4A and 4B, the diaphragm 39 and the top plate 37 are bent and deformed, and the volume of the blower chamber 36 is periodically changed.

As shown in FIG. 4A, when an alternating voltage is applied to the piezoelectric element 40 and the diaphragm 39 is bent toward the piezoelectric element 40, the volume of the blower chamber 36 increases. Along with this, air outside the piezoelectric blower 100 is sucked into the blower chamber 36 through the suction port 53, the vent path 31, and the vent hole 45. Although there is no outflow of air from the blower chamber 36, the inertial force of the air flow from the discharge port 24 to the outside of the piezoelectric blower 100 works.

As shown in FIG. 4B, when an AC voltage is applied to the piezoelectric element 40 to bend the diaphragm 39 toward the blower chamber 36, the volume of the blower chamber 36 decreases. Accordingly, air in the blower chamber 36 is discharged from the discharge port 24 through the vent hole 45 and the vent path 31.

At this time, the airflow discharged from the blower chamber 36 discharges air from the discharge port 24 while drawing air outside the piezoelectric blower 100 through the suction port 53 and the air passage 31. Therefore, if the pressure applied to the discharge hole from the outside of the piezoelectric blower 100 is 0 (hereinafter referred to as no load), the flow rate of the air discharged from the discharge port 24 increases by the flow rate of the drawn air.

Here, when the blower chamber 36 changes from the maximum expanded state shown in FIG. 4 (A) to the maximum contracted state shown in FIG. 4 (B), the distance between the projection 138 and the diaphragm 39 in the blower chamber 36 and the inside of the blower chamber 36. The distance between the projection 138 and the top plate 37 becomes narrower.

At this time, the air between the projection 138 and the diaphragm 39 in the blower chamber 36 and the air between the projection 138 and the top plate 37 in the blower chamber 36 are blown as shown by arrows in FIG. Moving to the center side of the chamber 36, the pressure in the central portion of the blower chamber 36 increases.

For this reason, when the blower chamber 36 changes from the maximum expanded state to the maximum contracted state, the ratio of the air in the blower chamber 36 discharged from the vent hole 45 to the outside of the blower chamber 36 becomes larger than before.

The mechanism is described in detail below. In general, the volume change rate H of the blower chamber is obtained by the equation H = (V ₁ −V ₂ ) / V ₁ . Comparing the piezoelectric blower 100 of the present embodiment with the conventional micro blower 900 shown in FIG. 10, the difference between the volume V ₁ when the blower chamber is fully expanded and the volume V ₂ when the blower chamber is maximum contracted (V ₁ − V ₂ ) is the same.

However, since the protrusion 138 is provided in the piezoelectric blower 100 of this embodiment, the volume V ₁ when the blower chamber is fully expanded is smaller than that of the conventional micro blower 900. That is, by providing the protrusion 138, the volume change rate H of the blower chamber is increased.

Thereby, the flow rate of air per displacement amount of the diaphragm 39 discharged from the inside of the blower chamber 36 to the outside of the blower chamber 36 through the vent hole 45 is increased as compared with the conventional case. Here, the displacement amount of the diaphragm 39 is determined by the power consumption to the piezoelectric element 40.

Therefore, according to the piezoelectric blower 100 of this embodiment, the discharge flow rate per power consumption can be greatly increased, and the necessary discharge flow rate can be ensured with low power consumption.

Further, in the piezoelectric blower 100 of this embodiment, the protrusion 138 is formed on the inner surface of the side plate 38 in a range not contacting the vibration plate 39 that is flexibly vibrated in the blower chamber 36. Therefore, according to the piezoelectric blower 100 of this embodiment, it is possible to prevent the vibrations of the vibration plate 39 and the top plate 37 from being inhibited by the protrusions 138.

Next, in the state shown in FIG. 3, when an AC drive voltage having a third-order mode frequency (third harmonic wave) is applied from the

external terminals

63 and 72 to the piezoelectric element 40, the diaphragm 39 is Bending vibration concentrically in a third-order mode that generates a vibration node F and two vibration antinodes. At the same time, the top plate 37 is also in the third mode with the bending vibration of the vibration plate 39 (in this embodiment, the vibration phase is delayed by 180 °) due to the pressure fluctuation of the blower chamber 36 accompanying the bending vibration of the vibration plate 39. Bend and vibrate concentrically.

Thereby, also in the tertiary mode, as shown in FIGS. 5A and 5B, the diaphragm 39 and the top plate 37 are bent and deformed, and the volume of the blower chamber 36 is periodically changed.

5A and 5B are cross-sectional views taken along the line SS of the piezoelectric blower 100 when the piezoelectric blower 100 shown in FIG. 1 is operated in the tertiary mode. Here, the arrows in the figure indicate the flow of air.

Comparing the piezoelectric blower 100 of the present embodiment with the conventional micro blower 900 shown in FIG. 10, the difference between the volume V ₁ when the blower chamber is fully expanded and the volume V ₂ when the blower chamber is maximum contracted (V ₁ − V ₂ ) is the same.

However, since the protrusion 138 is provided in the piezoelectric blower 100 of this embodiment, the volume V ₁ when the blower chamber is fully expanded is smaller than that of the conventional micro blower 900. That is, by providing the protrusion 138, the volume change rate H of the blower chamber is increased. Accordingly, even in the tertiary mode, the flow rate of air per displacement amount of the diaphragm 39 discharged from the inside of the blower chamber 36 to the outside of the blower chamber 36 through the vent hole 45 by providing the protrusion 138. Will increase.

Further, as shown in FIGS. 5A and 5B, the protrusion 138 has a large displacement in the vibration plate 39 and the top plate 37 that flexurally vibrate in the third-order mode, that is, from the center of the vibration plate 39 and the top plate 37. The inner surface of the side plate 38 is not longer than the length from the position of the vibration plate 39 in contact with the side surface of the blower chamber 36 to the bending vibration node F of the vibration plate 39 so as not to contact the region up to the vibration node with the shortest distance. Is formed. Therefore, even in the tertiary mode, the vibration of the diaphragm 39 can be prevented from being inhibited by the protrusion 138.

Therefore, even in the tertiary mode, the discharge flow rate per power consumption can be greatly increased, and the necessary discharge flow rate can be secured while maintaining low power consumption.

<< Second Embodiment of the Invention >>
Hereinafter, a piezoelectric blower 200 according to a second embodiment of the present invention will be described.

FIG. 6 is a sectional view of the piezoelectric blower 200 according to the second embodiment of the present invention. 7A and 7B are cross-sectional views of the piezoelectric blower 200 when the piezoelectric blower 200 shown in FIG. 6 is operated in the primary mode.

The difference between the piezoelectric blower 200 according to the second embodiment and the piezoelectric blower 100 according to the first embodiment is the shape of the protrusion 238. The protrusion 238 has a rectangular parallelepiped shape. Other configurations are the same.

Also in the piezoelectric blower 200 of this embodiment, when an AC drive voltage having a primary mode frequency (fundamental wave) is applied to the piezoelectric element 40 from the

external terminals

63 and 72, the diaphragm 39 is concentric in the primary mode. The top plate 37 bends and vibrates concentrically in the primary mode with the bending vibration of the vibration plate 39 (in this embodiment, the vibration phase is delayed by 180 °).

Thereby, also in the piezoelectric blower 200 of this embodiment, as shown in FIGS. 7A and 7B, the diaphragm 39 and the top plate 37 are bent and deformed, and the volume of the blower chamber 36 is periodically changed.

Also in the piezoelectric blower 200 of the second embodiment, when the blower chamber 36 is changed from the maximum expanded state shown in FIG. 7A to the maximum contracted state shown in FIG. 7B, the protrusions 238 and the diaphragm in the blower chamber 36 are obtained. The distance between the projection 39 and the top plate 37 in the blower chamber 36 becomes narrower.

At this time, the air between the projection 238 and the diaphragm 39 in the blower chamber 36 and the air between the projection 238 and the top plate 37 in the blower chamber 36 are blown as shown by arrows in FIG. Moving to the center side of the chamber 36, the pressure in the central portion of the blower chamber 36 increases. For this reason, when the blower chamber 36 changes from the maximum expanded state to the maximum contracted state, the rate at which the air in the blower chamber 36 is discharged from the vent hole 45 to the outside of the blower chamber 36 becomes larger than before.

Further, when the piezoelectric blower 200 of the present embodiment is compared with the conventional micro blower 900 shown in FIG. 10, the difference between the volume V ₁ when the blower chamber is fully expanded and the volume V ₂ when the blower chamber is maximum contracted (V ₁ -V ₂ ) is the same.

However, since the protrusion 238 is provided in the piezoelectric blower 200 of the present embodiment, the volume V ₁ at the time of maximum expansion of the blower chamber is smaller than that of the conventional micro blower 900. That is, also in the piezoelectric blower 200 of this embodiment, by providing the protrusion 238, the volume change rate H of the blower chamber is increased. Thereby, the flow rate of air per displacement amount of the diaphragm 39 discharged from the inside of the blower chamber 36 to the outside of the blower chamber 36 through the vent hole 45 is increased as compared with the conventional case.

Further, the protrusion 238 is also formed on the inner surface of the side plate 38 in a range where the vibration of the vibration plate 39 in the blower chamber 36 does not come into contact with a region where the vibration plate 39 is largely displaced (center portion of the vibration plate). Yes.

Therefore, according to the piezoelectric blower 200 of the second embodiment, the same effects as those of the piezoelectric blower 100 of the first embodiment can be obtained.

<< Third Embodiment of the Invention >>
Hereinafter, a piezoelectric blower 300 according to a third embodiment of the present invention will be described.

FIG. 8 is a cross-sectional view of a piezoelectric blower 300 according to a third embodiment of the present invention. 9A and 9B are cross-sectional views of the piezoelectric blower 300 when the piezoelectric blower 300 shown in FIG. 8 is operated in the primary mode.

The piezoelectric blower 300 according to the third embodiment is different from the piezoelectric blower 100 according to the first embodiment in the shape of the protrusion 338. The tip of the protrusion 338 has a convex curved surface shape, and the remaining body portion has a cylindrical shape. Other configurations are the same.

Also in the piezoelectric blower 300 of this embodiment, when an AC drive voltage having a primary mode frequency (fundamental wave) is applied from the

external terminals

63 and 72 to the piezoelectric element 40, the diaphragm 39 is concentric in the primary mode. The top plate 37 bends and vibrates concentrically in the primary mode with the bending vibration of the vibration plate 39 (in this embodiment, the vibration phase is delayed by 180 °).

Thereby, also in the piezoelectric blower 300 of this embodiment, as shown in FIGS. 9A and 9B, the diaphragm 39 and the top plate 37 are bent and deformed, and the volume of the blower chamber 36 is periodically changed.

Also in the piezoelectric blower 300 according to the third embodiment, while the blower chamber 36 is changed from the maximum expanded state shown in FIG. 9A to the maximum contracted state shown in FIG. The distance between the 338 and the diaphragm 39 and the distance between the projection 338 and the top plate 37 in the blower chamber 36 are reduced.

At this time, the air between the projection 338 and the diaphragm 39 in the blower chamber 36 and the air between the projection 338 and the top plate 37 in the blower chamber 36 are blown as shown by arrows in FIG. Moving to the center side of the chamber 36, the pressure in the central portion of the blower chamber 36 increases. For this reason, when the blower chamber 36 changes from the maximum expanded state to the maximum contracted state, the rate at which the air in the blower chamber 36 is discharged from the vent hole 45 to the outside of the blower chamber 36 becomes larger than before.

Further, when the piezoelectric blower 300 of the present embodiment is compared with the conventional micro blower 900 shown in FIG. 10, the difference between the volume V ₁ when the blower chamber is fully expanded and the volume V ₂ when the blower chamber is maximum contracted (V ₁ -V ₂ ) is the same.

However, since the protrusion 338 is provided in the piezoelectric blower 300 of this embodiment, the volume V ₁ when the blower chamber is fully expanded is smaller than that of the conventional micro blower 900. That is, also in the piezoelectric blower 300 of the present embodiment, the provision of the protrusion 338 increases the volume change rate H of the blower chamber. Thereby, the flow rate of air per displacement amount of the diaphragm 39 discharged from the inside of the blower chamber 36 to the outside of the blower chamber 36 through the vent hole 45 is increased as compared with the conventional case.

Further, the protrusion 338 is also formed on the inner surface of the side plate 38 in a range where the vibration of the vibration plate 39 in the blower chamber 36 does not contact the region where the displacement of the vibration plate 39 is large (the center portion of the vibration plate). Yes.

Therefore, according to the piezoelectric blower 300 of the third embodiment, the same effect as that of the piezoelectric blower 100 of the first embodiment can be obtained.

<< Other Embodiments >>
In the embodiment, air is used as the fluid, but the present invention is not limited to this. It can be applied even if the fluid is a gas other than air.

In the above embodiment, the piezoelectric element 40 is provided as a blower drive source, but the present invention is not limited to this. For example, it may be configured as a blower that performs pumping by electromagnetic driving.

In the above embodiment, the piezoelectric element 40 is made of a lead zirconate titanate ceramic, but is not limited thereto. For example, you may comprise from the piezoelectric material of lead-free piezoelectric ceramics, such as potassium sodium niobate type | system | group and alkali niobic acid type | system | group ceramics.

In the above embodiment, a unimorph type piezoelectric vibrator is used, but the present invention is not limited to this. A bimorph type piezoelectric vibrator in which the piezoelectric elements 40 are attached to both surfaces of the vibration plate 39 may be used.

In the above embodiment, the disk-shaped piezoelectric element 40, the disk-shaped diaphragm 39, and the disk-shaped top plate 37 are used, but the present invention is not limited to this. For example, these shapes may be rectangular or polygonal. Similarly, the shape of the protrusion is not limited to the shape of the above embodiment, and may be formed by a rectangular parallelepiped shape, a spherical shape, or a combination thereof.

In the above embodiment, the plurality of protrusions 138 are formed on the inner surface of the side plate 38, but the present invention is not limited to this. For example, one projection 138 may be formed on the inner surface of the side plate 38, and for example, an annular projection may be provided in contact with the inner periphery of the side plate 38.

In the above embodiment, the vibration plate of the piezoelectric blower is bent and vibrated at the frequency of the primary mode and the tertiary mode. However, the present invention is not limited to this. In implementation, the diaphragm may be bent and vibrated in an odd-order vibration mode that is a third-order mode or more that forms a plurality of vibration antinodes.

In the above embodiment, the top plate 37 bends and vibrates concentrically with the bending vibration of the diaphragm 39. However, the present invention is not limited to this. At the time of implementation, only the diaphragm 39 is flexibly vibrated, and the top plate 37 may not be flexibly vibrated with the flexural vibration of the diaphragm 39.

Finally, the description of the embodiment should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

DESCRIPTION OF SYMBOLS 2 ... Inner case 3 ... Outer case 3A ... Discharge port 4 ... Connection part 5A ... Elastic metal plate 5B ... Piezoelectric element 6 ... Blower chamber 7 ... Inflow passage 8 ... Opening part 9 ... Lid member 9A ... Suction port 17 ... Outer housing 18 ... Nozzle 24 ... Discharge port 31 ... Ventilation path 36 ... Blower chamber 37 ... Top plate 38 ... Side plate 39 ... Vibrating plate 40 ... Piezoelectric element 42 ... Cap 45 ... Vent hole 52 ... Protruding part 53 ... Suction port 55A-55D ... Cut off Notches 56A to 56D ... Screw hole 61 ... Center part 62 ... Projection part 63 ... External terminal 70 ... Electrode conduction plate 72 ... External terminal 73 ...

Internal terminal

100, 200, 300 ...

Piezoelectric blower

138, 238, 338 ... Projection 900 ... Micro blower

Claims

A vibration plate that vibrates and vibrates;
A driver that is provided on at least one main surface of the diaphragm and vibrates the diaphragm;
A first housing that forms a blower chamber together with the diaphragm,
The first housing has a top plate portion facing the diaphragm, and a side wall portion connecting the diaphragm and the top plate portion,
The top plate portion is formed with a vent hole that communicates the inside and outside of the blower chamber,
The side wall is formed with a protrusion that protrudes toward the center of the blower chamber.
2. The blower according to claim 1, wherein the protrusion is formed in the blower chamber in a range where it does not contact the vibration plate that bends and vibrates.
The vibration plate is flexibly vibrated in an odd-order vibration mode of a third-order mode or more that forms a plurality of vibration antinodes by the driver,
The protrusion is formed to have a length not more than a length from a position of the vibration plate in contact with a side surface of the blower chamber to a vibration node having the shortest distance among vibration nodes formed by bending vibration of the vibration plate. The blower according to claim 1 or 2.
The blower according to any one of claims 1 to 3, wherein the top plate portion bends and vibrates with bending vibration of the diaphragm.
A second casing in which the first casing is covered with a space to form a ventilation path between the first casing and a discharge port is formed in a region facing the vent; The blower according to claim 1, comprising: