JPH0352678A - Aerial ultrasonic generator and ultrasonic flocculating device - Google Patents

Abstract

PURPOSE:To flocculate suspended particles by providing a piezoelectric oscillator and diaphragm and equalizing the natural oscillation frequency of the diaphragm to the coupling resonance frequency of the piezoelectric oscillator. CONSTITUTION:The AC voltage of the frequency equal to the coupling resonance frequency of the piezoelectric oscillator 22 is impressed to the piezoelectric oscillator 22 at the time of operation of the ultrasonic flocculating device 62. The piezoelectric oscillator 22 is excited and the diaphragm 28 is makes curvilinear resonance oscillation. The ultrasonic waves of the high frequency are radiated from the diaphragm 28 toward the side wall of a duct 60. The sound fields of the ultrasonic waves are generated between the respective plate surface of the diaphragm 28 and the corresponding side walls of the duct 60. Relative speeds are generated among the large and small suspended particles when the suspended particles in the gas passing the inside of the duct 60 exist in the sound fields of the ultrasonic waves. These particles collide and join against and with each other and grow to the particles of larger diameters. The suspended particles are effectively flocculated and captured in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an aerial ultrasonic generator that emits ultrasonic waves into the air and an ultrasonic agglomeration device using the same. (Conventional technology) There is a method of agglomerating suspended particles in gas flowing through a duct using ultrasonic waves. As a conventional means for generating airborne ultrasonic waves, there is one that includes an ultrasonic transducer with a horn and a bent rectangular diaphragm. The attached ultrasonic transducer has a complicated structure of the aerial ultrasonic generating means, and the frequency of the ultrasonic waves emitted from the aerial ultrasonic generating means is low.Therefore, ultrasonic aggregation using conventional aerial ultrasonic generating means is difficult. However, because the frequency of airborne ultrasound is low, it is difficult to agglomerate submicron or smaller floaters using this method.The purpose of the present invention is to have a simple structure and emit high-frequency ultrasound. An object of the present invention is to provide an airborne ultrasonic generator capable of generating ultrasonic waves, and an ultrasonic agglomeration device capable of agglomerating submicron or smaller floaters using the same. The generator includes a piezoelectric vibrator having a columnar piezoelectric ceramic with electrodes provided on both end faces, an edge in the width direction fixed to the piezoelectric ceramic, and an axis in the longitudinal direction aligned with the axis of the piezoelectric ceramic. and at least one orthogonal rectangular diaphragm, the natural frequency of the diaphragm being approximately equal to the coupled resonant frequency of the piezoelectric vibrator.

The natural frequency of the diaphragm is f, the Young's modulus is E, and the density is ρ.
, Poisson's ratio is σ, thickness is h, pi is pi, and any one even number from 6 to 30, t is Neve n
, 3 to 9, any one odd number is Nodd, it is desirable that the length KL of the diaphragm satisfies the following formula (a). Here, the width K of the diaphragm
．． satisfies the following equation, and C0 is given by the following equation.

Aerial ultrasonic generator described in the width direction. (3) A rectangular first frame plate whose edges in the width direction protrude perpendicularly to the diaphragm, and an aerial ultrasonic generator described in the width direction. (3)
a rectangular second frame plate located at the other edge along the width direction and protruding at right angles to the diaphragm, and an edge written in the width direction extending in the width direction of the first frame plate; The other edge along the width direction of the second frame plate cooperates with the first and second frame plates and the diaphragm to cross the second frame plate. and a rectangular third frame plate defining a cylinder whose surface shape is approximately square, and the dimensions and material of the first, second and third frame plates are the same as the dimensions and material of the diaphragm. It is preferable that the dimensions and material of the plate be the same. Airborne ultrasound generator described in longitudinal direction. (3) A rectangular first frame plate whose edges in the longitudinal direction protrude perpendicularly to the diaphragm, and an aerial ultrasonic generator as described in the longitudinal direction.

(3) a rectangular second frame plate whose other edge along the longitudinal direction projects at right angles to the diaphragm, and whose edge along the longitudinal direction is the other edge of the first frame plate; The other edge of the second frame plate along the longitudinal direction is the first frame plate.
, a third frame plate having a rectangular shape that cooperates with the second frame plate and the diaphragm to define a cylinder having a substantially square cross-sectional shape;
The dimensions and materials of the first, second and third frame plates are as follows:
It is preferable that the dimensions and material of the diaphragm are the same. It is preferable that the piezoelectric ceramic is provided with a support that can be attached to a structure or the like, and that the piezoelectric ceramic is supported by the support. The present invention is an apparatus for agglomerating suspended particles in gas flowing in a duct such as a flue, which comprises a support mounted in the duct and at least one airborne particle supported by the support. The aerial ultrasonic generation mechanism includes a piezoelectric vibrator having a columnar piezoelectric ceramic whose outer peripheral surface is fixed to the support base and electrodes are provided on both end surfaces, and and at least one rectangular diaphragm whose edges are fixed to the piezoelectric ceramic and whose longitudinal axis is orthogonal to the axis of the piezoelectric ceramic, and the natural frequency of the diaphragm is equal to that of the piezoelectric vibrator. Almost equal to the coupled resonant frequency. Aerial ultrasonic generator described in the width direction. (3) A rectangular first frame plate whose edges in the width direction protrude perpendicularly to the diaphragm, and an aerial ultrasonic generator described in the width direction. (3)
a rectangular second frame plate located on the other edge along the width direction and protruding at right angles to the diaphragm, and an edge written in the width direction extending in the width direction of the first frame plate; The other edge along the width direction of the second frame plate cooperates with the first and second frame plates and the diaphragm to cross the second frame plate. a rectangular third frame plate defining a cylinder having a substantially square surface shape, the dimensions and material of the first, second and third frame plates being equal to the dimensions and material of the diaphragm; Preferably, the axis of the pipe is substantially parallel to the axis of the duct. Airborne ultrasound generator described in longitudinal direction. (3)
A rectangular first frame plate whose edges in the longitudinal direction protrude perpendicularly to the diaphragm; and an airborne ultrasound generator in the longitudinal direction. (3) a rectangular second frame plate whose other edge along the longitudinal direction projects at right angles to the diaphragm, and whose edge along the longitudinal direction is the other edge of the first frame plate; The other edge of the second frame plate along the longitudinal direction cooperates with the first and second frame plates and the diaphragm to form a cylinder having a substantially square cross-sectional shape. and a third frame plate having a rectangular shape as defined;
The dimensions and materials of the first, second and third frame plates are as follows:
Preferably, the dimensions and material of the diaphragm are the same, and the axis of the diaphragm is substantially parallel to the axis of the duct. {Operations and Effects of the Invention} When an AC voltage having a frequency equal to the coupled resonant frequency of the piezoelectric vibrator is applied to the piezoelectric vibrator, the piezoelectric vibrator is vibrated at the coupled resonant frequency. Since the edge described in the width direction of the diaphragm is fixed to the piezoelectric ceramic, the diaphragm can freely move the other edge along the width direction of the diaphragm by vibration displacement of the piezoelectric ceramic. Because it undergoes flexural resonance vibration with the cantilevered beam shape at the end,
Ultrasonic waves are emitted from the diaphragm in a direction perpendicular to its surface. The frequency of the ultrasonic wave is equal to the natural frequency of the diaphragm. As a result, it is possible to generate ultrasonic waves in the air with a simple structure. Further, it is desirable that the natural frequency of the diaphragm is approximately equal to the resonant frequency of the piezoelectric vibrator, but it is relatively easy to achieve a high resonant frequency, and high frequency ultrasonic waves can be generated in the air. Furthermore, the ultrasonic waves cannot be heard by large animals or animals, and there is no risk of affecting the environment. The length dimension KL of the resonance plate satisfies formula (a),
When the width dimension Kw of the diaphragm satisfies equation (b), the nodes of the standing waves on the diaphragm coincide with the edges along the width direction of the diaphragm, so that the ultrasonic wave of the diaphragm Radiation efficiency is improved. Furthermore, the first, second, and third frame plates are provided, and the first, second, and third frame plates and the diaphragm cooperate with each other to form a cylinder having a substantially square cross-sectional shape. By specifying this, high-frequency ultrasonic waves are radiated into the casing, and an ultrasonic stage is created within the casing. According to the ultrasonic agglomeration device of the present invention, an ultrasonic sound field is created in the space between the plate surface of the diaphragm and the inner circumferential surface of the duct facing it. When a plurality of suspended particles in a gas pass through an ultrasonic sound field, the suspended particles are vibrated by the vibrations of the gas tL, and the suspended particles collide with each other and coalesce to grow into large-diameter particles.

In addition, since a high-frequency ultrasonic sound field is created, collisions and coalescence between small-diameter suspended particles and even smaller-diameter suspended particles occur more frequently, making it possible to aggregate submicron or smaller suspended particles. As a result, harmful airborne particles can be prevented from being emitted into the atmosphere. Further, the aerial ultrasonic generation mechanism includes the first, second, and third frame plates, and the first, second, and third frame plates and the diaphragm resonate with each other to form a cross-sectional shape. By defining a cylinder having a substantially square shape, a high-frequency sound field is created within the cylinder, so that floating particles passing through the cylinder collide with each other and coalesce, causing agglomeration. Furthermore, since the axis of the cylinder is parallel to the axis of the duct, the aerial ultrasonic generation mechanism can be easily arranged within the duct and effectively with respect to the cross section of the duct, improving the aggregation efficiency of suspended particles. You can (Example) Fig. 1 is a front view showing an embodiment of the aerial ultrasonic generator of the present invention, Fig. 2 is a surface measurement view of the airborne ultrasonic generator of Fig. 1, and Fig. 3 is the same as Fig. 1. Fig. 4 is a front view showing another embodiment of the airborne ultrasonic generator, and Fig. 5 is a perspective view of a piezoelectric vibrator used in the airborne ultrasonic generator. 6 is a surface view of the aerial ultrasonic generator shown in FIG. 5, FIG. 7 is a front view showing still another embodiment of the aerial ultrasonic generator, and FIG. 7 is a cross-sectional view taken along line A-A in FIG. 7. The aerial ultrasonic generator 10 includes a support base 12, as shown in FIGS. 1 to 3. The support stand 12 is attached to a horizontal support surface 14 such as a structure, and one surface is attached to the horizontal support surface 14.
4, and a square plate 18 that is fixed to the plate 16 on one side and stands up at right angles to the plate 16. A through hole 20 is provided in the center of the plate 18.

The plate 18 is arranged on one end side of the plate l6 so that the axis of the through hole 20 is parallel to the axis of the plate 16 in the width direction.
A piezoelectric vibrator 22 is attached to the plate 18 via a through hole 20. The piezoelectric vibrator 22 has a cylindrical piezoelectric ceramic 24, as shown in FIG. Each end face of the piezoelectric ceramic 24 has an electrode 26 (however, in FIG. 3, the electrode 26 is drawn to have a certain thickness, but in reality, the electrode 26 is ignored compared to the length of the piezoelectric ceramic 24). ) is provided. It has already been reported that the vibration of the piezoelectric vibrator 22 can be considered as a two-dimensional combination of the vibration in the axial direction and the spreading vibration of its cross section. When the length of the piezoelectric ceramic 24 is 1, the density is ρ, and the Young's modulus is E, the resonance angular frequency ω of longitudinal vibration in the axial direction of the piezoelectric vibrator 22 is given by equation (1). When the radius of the piezoelectric ceramic is γ and the Poisson's ratio is σ, the resonance angular frequency ω in the radial direction of the piezoelectric vibrator 22 is given by equation (2). ...... (2) However, ζ is the root of the Bessel function J shown in equation (3). ζ． yo (ζ)-(1-σ)J1 (ζ)=0...
...(3) Generally, the resonant angular frequency of an isotropic vibrating body is given by equation (4). ω' (1-3μ2-2μ3) - ω' (1-μ2) (ωll2+ω12+ω2)
+ω2 (ω, 2ω, 2+ω, 2ω.

+ωc2ω. ′)−ω＆′ωb2ωc′20・・・・・・
(4) The basic formula for the three-dimensional coupled vibration of a cylinder is ω in equation (4). =ωJ,ω1=ω,. ω. =ω,・・・・・・(5
) can be obtained.

(ω + ω, 〉 +ω, ω `` } = 0 ...... 〈6) In equation (6), the second term is ω4 (1-η2) - ω2 (ω, ′+ω 2)+ω,
2ω12=0 (7), which coincides with the expression for the two-dimensional combination of ω and ω, where the apparent coupling coefficient is η. Piezoelectric ceramic 2 polarized in the length direction
4, the vibration obtained from the first term is not observed.

The piezoelectric ceramic 24 is made of 71A material manufactured by TDK, and has a diameter of 10na+n and a length of 10nm. One of the coupling resonance frequencies of the piezoelectric vibrator 22 is 135 KHz from equations (1) to (4). An edge along one width direction of a rectangular diaphragm 28 is bonded to the edge of one end surface of the piezoelectric ceramic 24 with an epoxy resin adhesive. The diaphragm 28 is attached to the piezoelectric ceramic 24 such that its longitudinal axis is orthogonal to the axis of the piezoelectric ceramic 24.
The diaphragm 28 is arranged parallel to the plate 18 and perpendicular to the other surface of the plate 16. The diaphragm 28 is vibrated by the vibration displacement of the piezoelectric ceramic 24 in the axial direction. Applying the theory regarding the rectangular bending vibration of the free end to the vibration mode of the diaphragm 28, the eigenvalue number f of the diaphragm 28 is (9
) is given by the formula. However, C0 is obtained by the following formula, and the constant K specific to the material of the diaphragm 28 is the length,
h is the thickness dimension, m is an eigenvalue satisfying CosmsXcosh=1, E is Young's modulus, ρ is density, and σ is Poisson's ratio.

When the diaphragm 28 is vibrated by the piezoelectric vibrator 22, the natural frequency f of the diaphragm 28 is approximately equal to the coupled resonant frequency of the piezoelectric vibrator 22, so the frequency of the diaphragm 28 is equal to the natural frequency. At that time, an ultrasonic wave having a frequency equal to the natural frequency f is emitted from the diaphragm 28 in a direction perpendicular to the plate surface. In this example, since the coupling resonance angular frequency of the piezoelectric vibrator 22 is 135 KHz, if the material of the diaphragm 28 is aluminum and its natural frequency is 139 KHz, then from equations (9) and (10), The thickness h of the diaphragm 28 is IIWI1. The node of bending resonance vibration is the diaphragm 28
In the vibration mode that appears perpendicular to the long side of and at regular intervals, the interval d between the nodes is given by equation (11).
The length dimension KL of the diaphragm 28 is expressed by the formula (12), and its width dimension K
．． is given by equation <13>, and the edge of one short side of the diaphragm 28 becomes a node, so the radiation efficiency of ultrasonic waves from the diaphragm 28 becomes good. KL = (Nev
e n−}4) d ”=・
(12) K. = Nodd d =
=(13) However, Neven is an even number (any number from 6 to 30 is acceptable), and Nodd is an odd number (any number from 3 to 9 is acceptable). In this example, assuming that the natural frequency f is 139 KHz and the thickness h is 1. By each of the above, the diaphragm 2
The length dimension KL of 8 is 106.6 mm, and its width dimension K is 2.
It will be 9m. As a result, ultrasonic waves with a high frequency of 139 KHz are efficiently radiated from the diaphragm 28. Further, as shown in FIGS. 1 and 2, in order to prevent the diaphragm 28 from bending toward the plate 16 of the support base 12,
It is preferable that the edges of the diaphragm 28 in the longitudinal direction are supported by a support member 30. When the aerial ultrasonic generator 10 is driven, the piezoelectric vibrator 22 has:
A 135 KHz alternating current is applied through electrode 26. The piezoelectric vibrator 22 is excited at a frequency of 135 KHz,
The diaphragm 28 bends and vibrates at a frequency of 139KHz. Ultrasonic waves with a frequency of 139 KHz are emitted from the diaphragm 28. Referring to FIG. 4, the aerial ultrasonic generator 31 includes two rectangular diaphragms 28. One diaphragm 2
The edge shown in the width direction of 8 is bonded to the edge of one end surface of the piezoelectric ceramic 24. The other edge of the other diaphragm 28 along the width direction is bonded to the piezoelectric ceramic 24 such that it faces the edge of the one diaphragm 28 in the width direction. Referring to FIGS. 5 and 6, the aerial ultrasound generator 32 includes a support base 34 that is attached to a structure. The support base 34 is made of an L-shaped member, and one side is provided with a plurality of holes 36 for receiving fixing tools, and the other side is provided with a through hole 38 that penetrates in the thickness direction. The pressure vibrator 22 is attached to the support base 34 via a through hole 38 .

The piezoelectric vibrator 22 has electric fl! on both end surfaces. 26 is provided. An edge shown in the width direction of a rectangular diaphragm 28 is bonded to the edge of one end surface of the piezoelectric ceramic 24. The length dimension of the diaphragm 28 is 106.6
M, its width dimension is 2911l+, its thickness dimension is 1 ken,
Its natural frequency is 139KHz, and its material is aluminum. The edge portion of the diaphragm 28 in the width direction is connected to the edge portion of the rectangular first frame plate 40 in the width direction. 1st
The frame plate 40 is perpendicular to the diaphragm 28. Vibration plate 2
The other edge of the rectangular second frame plate 42 along the width direction is abutted against the edge of the rectangular second frame plate 42 along the width direction. Second
The frame plate 42 of is parallel to the first frame plate 40. The first frame plate 40 and the second frame plate 42 are connected by a rectangular third frame plate 44. The edge described in the width direction of the third frame plate 44 is such that the other edge of the first frame plate 40 is the other edge of the second frame plate 42, and the other edge of the second frame plate 42 is the third frame. The plate 44 is arranged parallel to the diaphragm 28. The dimensions and material of the first, second, and third frame plates 40, 42, and 44 correspond to the dimensions and material of the diaphragm 28. Equally, the first, second and third frame plates 40, 42, 44 and the diaphragm 2
8 is mutually co-facing and MI! Define a cylinder with an almost square cross-section. When the aerial ultrasonic generator 32 is driven, the diaphragm 28 undergoes flexural resonance vibration by the piezoelectric vibrator 22, and an ultrasonic sound field is created within the vibrator. Furthermore, the frequency of the emitted ultrasonic waves is 139KHz. As shown in FIGS. 7 and 8, the aerial ultrasonic generator 46 includes a support base 48, which is an L-shaped member attached to a structure, and is supported by the support base 48 through its through hole 50, and has both ends. A piezoelectric vibrator 22 has a piezoelectric ceramic 24 on which an electrode 26 is provided on the surface, an edge described in the width direction is glued to the edge of one end surface of the piezoelectric ceramic 24, and the longitudinal axis is the piezoelectric ceramic 24. 24 and a rectangular diaphragm 28 perpendicular to the axis of the diaphragm 24. From the diaphragm 28, a rectangular first frame plate 52 and a second rectangular frame plate 52 are connected.
A frame plate 54 projects perpendicularly to the diaphragm 28.
The edge described in the longitudinal direction of the first frame plate 52 corresponds to the diaphragm 28
The edge drawn in the longitudinal direction of the second frame plate 54 is connected to the other edge drawn in the longitudinal direction of the diaphragm 28 . The first frame plate 52 and the second frame plate 54 are connected by a rectangular third frame plate 56. The edge of the third frame plate 56 in the longitudinal direction is connected to the other edge of the first frame plate 52, and the other edge is connected to the other edge of the second frame plate 54. The third frame plate 56 is arranged parallel to the diaphragm 28. It has been done. Each of the first, second and third frame plates 52, 54, 56 and the diaphragm 28 has the same dimensions and material. When the dimensions and material of the diaphragm 28 are equal to those of the diaphragm of the aerial ultrasonic generator 32, each of the first, second, and third frame plates 52, 54, 56 and the diaphragm 28 cooperate with each other. A 139 KHz ultrasonic sound field is created within the cylinder defined by the following.

An ultrasonic agglomeration device 62 is used as a device for agglomerating floating particles in gas flowing through a duct 60 such as a flue. FIG. 9 is a diagram showing the installed state of the ultrasonic agglomeration device of the present invention. As shown in FIG. 9, the ultrasonic wave collecting device 62 includes a support 64 installed inside a rectangular cylindrical duct 60. The support stand 64 is fixed to the lower surface of the duct 60 and includes an elongated plate 66 extending in the axial direction of the duct 60, each of which is spaced apart from the plate 66 at a constant interval and whose thickness direction is in the width direction of the plate 66. at least one plate 6 vertically rising from the plate 66;
8. A through hole 70 is provided in the center of each plate 68 in the thickness direction thereof. The support stand 64 is
The elongated plate 66 is disposed within the duct 60 such that the edge described in the longitudinal direction is located at one even corner of the lower surface of the duct 60. At least one aerial ultrasound generating mechanism 72 is attached to the support base 64. The aerial ultrasonic generation mechanism 72 includes a piezoelectric vibrator 22 having a piezoelectric ceramic 24 provided with electrodes 26 on both end faces, and an edge described in the width direction bonded to the edge of the end face of one of the piezoelectric ceramics 24. , and at least one rectangular diaphragm 28 whose longitudinal axis is orthogonal to the axis of the piezoelectric ceramic 24. It is fitted into the through hole 70.

The edges of the diaphragm 28 in the longitudinal direction are supported by a support member 30. When the ultrasonic agglomeration device 62 is in operation, an alternating current voltage having a frequency equal to the coupling resonance frequency of the piezoelectric vibrator 22 is applied to the piezoelectric vibrator 22 . The piezoelectric vibrator 22 is excited, and the diaphragm 2
8 vibrates in bending resonance. High frequency ultrasonic waves are radiated from the diaphragm 28 toward the side wall of the duct 60. 1' of each mask of the diaphragm 28 and the corresponding duct 60!
An ultrasonic sound field is created between the I walls. When a plurality of suspended particles in the gas flowing through the duct 60 are located in the ultrasonic sound field, each suspended particle is vibrated by the vibration of the gas, but there is a relative velocity between these large and small suspended particles. occurs, and the two collide and coalesce to grow into large-diameter particles. Further, the diaphragm 28 is the diaphragm 28 of the aerial ultrasonic generator 10.
139KH when it has the same shape, dimensions and material as
Experiments showed that because an ultrasonic sound field with a high frequency of z is created, collisions and coalescence between small-diameter suspended particles and even smaller-diameter suspended particles occur more frequently, making it possible to aggregate submicron or smaller suspended particles. has been confirmed. As a result, it is possible to prevent harmful small-sized suspended particles from being released into the atmosphere. Moreover, FIG. 10 shows the installation state of another embodiment of the ultrasonic agglomeration device. The ultrasonic aggregation device 74 includes a plurality of supports 78 mounted within a duct 76. The support stand 78 is made of an elongated plate, one end of which is fixed to the top of the duct 76, and the other end fixed to the bottom of the duct 76. Each support stand 78 is provided with a plurality of through holes (not shown) passing through the support stand 78 in its thickness direction. Each through hole is
They are arranged at regular intervals along the longitudinal direction of the support base 78. Each support stand 78 is arranged within the duct 76 such that the axis of the through hole is perpendicular to the measuring section of the duct 76. Each through-hole of one support pedestal 78 coincides with the axis of the corresponding through-hole of the other support pedestal 78. The support base 78 is attached with the same number of aerial ultrasonic generation mechanisms 84 as the number of through holes thereof. The aerial ultrasonic generator 41I84 includes a piezoelectric vibrator 22 having a piezoelectric ceramic 24 provided with an electric conductor (i26) on both end faces, and an edge described in the width direction at the edge of one end face of the piezoelectric ceramic 24. glued,
It includes a rectangular diaphragm 28 whose longitudinal axis is orthogonal to the axis of the piezoelectric ceramic 24, a first frame plate 52, a second frame plate 54, and a third frame plate 56. Each of the first, second and third frame plates 52, 54, 56 has the same dimensions and material as the diaphragm 28.

The first, second and third frame plates 52, 54, 56 and the diaphragm 28 cooperate with each other to define a cylinder having a substantially square cross-sectional shape. The length of the diaphragm is equal to the length of the diaphragm 28, and the width of the diaphragm is approximately equal to the width of the diaphragm 28. Each of the aerial ultrasonic wave generating structures 84 is supported by the support base 78 by fitting each piezoelectric ceramic 24 into a corresponding through hole of the support base 78. Each aerial ultrasonic wave generation mechanism 84 has an axis line of the respective fibers connected to the duct 76.
Since the duct 76 is arranged on the support stand 78 so as to be parallel to the axis of the duct 76, the cross section of the duct 76 can be effectively utilized. Since each aerial ultrasonic generating i-ellipse 84 creates an ultrasonic sound field within the tube, floating particles passing through the tube collide with each other and coalesce to aggregate. Further, instead of the illustrated example, the length dimensions of the first, second, and third frame plates and the diaphragm defined by the diaphragm are equal to the width dimension of the diaphragm 28, and the width dimension is the length of the diaphragm 28. The first and second
, the third frame plate and the diaphragm can be formed into a cylinder having the shape shown in FIGS. 7 and 8. Referring to FIG. 11, an ultrasonic condensing device 88 is disposed within the duct 86. FIG. 11 is a diagram showing the installation state of yet another embodiment of the ultrasonic agglomeration device. The ultrasonic aggregation device 88 includes a plate-shaped support 90. A hole (not shown) extending in the thickness direction is provided approximately at the center of the support base 90, and the hole has a hole (not shown) extending in the thickness direction.
A support rod 92 made of conductive material is inserted. The support rod 92 is insulated by an insulating material (not shown). A pair of aerial ultrasonic generating R structures 94 are attached to the support rod 92. One aerial ultrasonic generation mechanism 94 has a piezoelectric vibrator 22 fixed to one end of a support rod 92. Pressure! One end surface of the vibrator 22 faces one end of the support rod 92, and the pressure! An electrode 26 provided on one end face of the vibrator 22 is electrically connected to a support rod 92. A pair of diaphragms 28 are fixed to the other end face of the piezoelectric vibrator 22. One of the diaphragms 28 cooperates with the first, second, and third frame plates 40, 42, and 44 to define a cylinder having a substantially square cross-sectional shape. The length dimension of the strip is equal to the width dimension of one diaphragm 28, and the opening dimension thereof is equal to the width dimension of one diaphragm 28.
Equal to the length dimension of 8. The edge along the width direction of one diaphragm 28 is fixed to the edge of the other end surface of the piezoelectric vibrator 22, and the other edge along the width direction of one diaphragm 28 is fixed to the edge of the other end surface of the piezoelectric vibrator 22.
It is not connected to the second frame plate 42. The other diaphragm is
Similar to one of the diaphragms 28, it cooperates with the first, second, and third frame plates 40, 42, and 44 to define a cylinder with a substantially square cross-sectional shape. One of the airborne ultrasonic generation mechanisms 94 is mounted on a support rod 9 so that the axis of each cylinder is parallel to the axis of the duct 86.
It is attached to 2. To prevent deflection of each plate, each first plate 40 can be supported by a bracket 96 attached to the duct 86. The other aerial ultrasound generating mechanism 94 has a piezoelectric vibrator 22 fixed to the other end of the support rod 92. Piezoelectric vibrator 2
One end face of the piezoelectric vibrator 22 faces the end face of the support rod 92, and is electrically connected to the support rod 92 provided on one end face of the piezoelectric vibrator 22. In this case, a pair of diaphragms 28 are fixed. Each diaphragm 28 has a corresponding first, second and third frame plate 40.42.44.
The electrode 26 provided on the other end surface of the piezoelectric vibrator 22 of each aerial ultrasonic generation mechanism 94 when the ultrasonic condensing device 88 is actuated cooperates with the ultrasonic aggregation device 88 to define a cylinder with a substantially square cross-sectional shape. is connected to one side of an AC power source (not shown) and is provided on one end face of the piezoelectric vibrator 22.
#126 is connected to the other AC power source through the support rod 92. When an AC power source with a frequency equal to the coupling resonance frequency of the piezoelectric vibrator 22 is applied to the piezoelectric vibrator 22, an ultrasonic sound field is created within each cylinder.

[Brief explanation of drawings]

Fig. 1 is a front view showing an embodiment of the aerial ultrasonic generator of the present invention, Fig. 2 is a side view of the airborne ultrasonic generator of Fig. 1, and Fig. 3 is the aerial ultrasonic generator of Fig. 1. FIG. 4 is a front view showing another embodiment of the aerial ultrasonic generator, and FIG. 5 is a front view showing still another embodiment of the aerial ultrasonic generator. Fig. 6 is a side view of the aerial ultrasonic generator shown in Fig. 5, Fig. 7 is a front view showing still another embodiment of the airborne ultrasonic generator, and Fig. 8 is A-A in Fig. 7. A cross-sectional view taken along the line, FIG. 9 is a cross-sectional view showing an installed state of one embodiment of the ultrasonic agglomeration device of the present invention, and FIG. 10 is a cross-sectional view showing an installed state of another embodiment of the ultrasonic agglomeration device. FIG. 11 is a cross-sectional view showing an attached state of still another embodiment of the ultrasonic aggregation device. 10,31,32.46...Airborne ultrasonic generator, 12
, 34, 48, 64, 78.90... support stand, 22.
... Piezoelectric vibrator, 24... Piezoelectric ceramic, 26... Electrode, 28... Vibration plate, 40.52... First frame plate, 4
2.54...Second frame plate, 44.56...Third frame plate, 60,76.86...Duct, 62,74,88
...Ultrasonic condensation device, 72, 84, 94...Aerial ultrasonic generation mechanism.

Claims (8)

[Claims] (1) A piezoelectric vibrator having a columnar piezoelectric ceramic with electrodes provided on both end faces, one edge along the width direction being fixed to the piezoelectric ceramic, and the axis of the longitudinal direction being aligned with the axis of the piezoelectric ceramic. and at least one orthogonal rectangular diaphragm, the natural frequency of the diaphragm being approximately equal to the coupled resonant frequency of the piezoelectric vibrator. (2) The natural frequency of the diaphragm is f, Young's modulus is E, density is ρ, Poisson's ratio is σ, thickness is h, pi is π,
Neve any one even number from 6 to 30
n, any one odd number from 3 to 9
Then, the length K_L of the diaphragm is calculated by the following formula K_L=(Neven-1/2) {(πC_Dh)/(
2f)}^1^/^2...(a) is satisfied, and the width K_W of the diaphragm is calculated using the following formula K_L=Nodd{(πC_Dh)/(2f)}^1^
/^2...(b) is satisfied, C_D is the following formula C_D={(E)/(12ρ(1-σ^2))}^1^
The aerial ultrasonic generator according to claim 1, given by /^2...(c). (3) a rectangular first frame plate whose one edge along the width direction is connected to one edge along the width direction of the diaphragm and which projects at right angles to the diaphragm; a rectangular second frame plate whose one edge along the width direction is located at the other edge along the width direction of the diaphragm and projects at right angles to the diaphragm; and one edge along the width direction. is connected to the other edge along the width direction of the first frame plate, and the other edge along the width direction is connected to the other edge along the width direction of the second frame plate,
a rectangular third frame plate that cooperates with the first and second frame plates and the diaphragm to define a cylinder having a substantially square cross-sectional shape; The aerial ultrasonic generator according to claim 1 or 2, wherein the dimensions and material of the frame plate 3 are equal to the dimensions and material of the diaphragm. (4) a rectangular first frame plate whose one longitudinal edge is connected to the longitudinal edge of the diaphragm and projects perpendicularly to the diaphragm; a rectangular second frame plate whose one edge along the longitudinal direction is connected to the other edge along the longitudinal direction of the diaphragm and which projects at right angles to the diaphragm; and one edge along the longitudinal direction. is connected to the other edge of the first frame plate, the other edge along the longitudinal direction is connected to the other edge of the second frame plate, and the first,
a third frame plate having a rectangular shape that cooperates with the second frame plate and the diaphragm to define a cylinder having a substantially square cross-sectional shape;
The dimensions and materials of the first, second and third frame plates are as follows:
Claim 1 or 2: The dimensions and material of the diaphragm are the same.
The aerial ultrasonic generator described in . (5) Claims 1 and 2, further comprising a support base attached to a structure or the like, and the piezoelectric ceramic is supported by the support base.
4. The aerial ultrasonic generator according to 3 or 4. (6) A device for agglomerating suspended particles in gas flowing through a duct such as a flue, which includes a support mounted in the duct and at least one aerial superstructure supported by the support. a piezoelectric vibrator having a cylindrical piezoelectric ceramic whose outer peripheral surface is fixed to the support base and electrodes are provided on both end surfaces; at least one rectangular diaphragm having one edge fixed to the piezoelectric ceramic and having a longitudinal axis perpendicular to the axis of the piezoelectric ceramic, the natural frequency of the diaphragm being the same as that of the piezoelectric vibrator. Ultrasonic aggregation device approximately equal to the coupling resonant frequency. (7) a rectangular first frame plate whose one edge along the width direction is connected to the one edge along the width direction of the diaphragm and which projects at right angles to the diaphragm; a rectangular second frame plate whose one edge along the width direction is located at the other edge along the width direction of the diaphragm and projects at right angles to the diaphragm; and one edge along the width direction. is connected to the other edge along the width direction of the first frame plate, and the other edge along the width direction is connected to the other edge along the width direction of the second frame plate,
a rectangular third frame plate that cooperates with the first and second frame plates and the diaphragm to define a cylinder having a substantially square cross-sectional shape; 7. The ultrasonic condensing device according to claim 6, wherein the dimensions and material of the frame plate No. 3 are equal to the dimensions and material of the diaphragm, and the axis of the cylinder is substantially parallel to the axis of the duct. (8) a rectangular first frame plate whose one longitudinal edge is connected to the longitudinal edge of the diaphragm and projects perpendicularly to the diaphragm; a rectangular second frame plate whose one edge along the longitudinal direction is connected to the other edge along the longitudinal direction of the diaphragm and which projects at right angles to the diaphragm; and one edge along the longitudinal direction. is connected to the other edge of the first frame plate, the other edge along the longitudinal direction is connected to the other edge of the second frame plate, and the first,
a third frame plate having a rectangular shape that cooperates with the second frame plate and the diaphragm to define a cylinder having a substantially square cross-sectional shape;
The dimensions and materials of the first, second and third frame plates are as follows:
7. The ultrasonic aggregation device according to claim 6, wherein the dimensions and material of the diaphragm are equal, and the axis of the cylinder is substantially parallel to the axis of the duct.