CN110662145B

CN110662145B - A sine stepped horn-shaped acoustic transducer and a transducer method

Info

Publication number: CN110662145B
Application number: CN201910973320.8A
Authority: CN
Inventors: 贺西平; 汪彦军; 刘强
Original assignee: Shaanxi Normal University
Current assignee: Shaanxi Normal University
Priority date: 2019-10-14
Filing date: 2019-10-14
Publication date: 2021-05-11
Anticipated expiration: 2039-10-14
Also published as: CN110662145A

Abstract

The invention belongs to the technical field of mechanical vibration, and relates to a sinusoidal stepped horn-shaped acoustic transducer and an energy conversion method. Between adjacent vibration pitch lines, on the section of the horn, the intersection of the front cover and the horn bus is the origin, the extension line of the horn bus is the x-axis, and the straight line extending through the origin to the direction of the sinusoidal step protrusion is the y-axis. The vibration phase of the horn is changed. The phase at any point on the sine step is πsin (πs), and it is radiated through the inner surface of the horn and the sine step surface, and the sound pressure is superimposed on the central axis of the horn to make the radiated sound field directivity. Sharp, the voltage emission response is improved. The invention has the characteristics of small size, simple structure, sharp directivity of the radiated sound field and high voltage emission response.

Description

Sinusoidal stepped horn-shaped acoustic transducer and transduction method

Technical Field

The invention belongs to the technical field of mechanical vibration, and particularly relates to a sinusoidal stepped horn-shaped acoustic transducer and an energy conversion method.

Background

High power radiated sound waves radiated into fluid media, particularly into air media, have many applications such as acoustic levitation, acoustic agglomeration, acoustic dedusting, acoustic bird scaring, and the like. In order to radiate high-power sound waves into an air medium, the mechanical impedance of the transducer needs to be well matched with the acoustic impedance of the air medium, the composite bending vibration transducer is proposed by Gallego, the spanish scholars at most, the composite bending vibration transducer is composed of a thin disk-shaped radiator and a piezoelectric sandwich type longitudinal vibration transducer, the transducer is connected with the center of the disk, the piezoelectric transducer excites longitudinal vibration to cause the disk to bend and radiate the high-power sound waves into the air medium, a large-area thin disk works in a bending vibration mode, but the composite bending vibration transducer is used for ensuring that the frequencies of the thin disk-shaped radiator and the piezoelectric sandwich type longitudinal vibration transducer are consistent to generate resonance, the requirement on the design precision of equipment is high, and in addition, the composite bending vibration transducer has the defects that the diameter of the disk is larger, the lower the frequency is the larger the size, therefore, the volume is larger in the application environment requiring low frequency, the directivity in the radiation sound field is poor, and the voltage emission response is low.

Disclosure of Invention

The technical problem to be solved by the invention is to overcome the defects of the device, namely to provide a sinusoidal stepped horn-shaped acoustic transducer which has small size, simple structure, sharp directivity of a radiation sound field and high voltage emission response.

Meanwhile, the invention also provides a transduction method for improving the voltage emission response performance of the acoustic transducer, which is realized by using the sinusoidal stepped horn-shaped acoustic transducer and the transduction method.

The technical scheme adopted by the invention is as follows:

a sinusoidal step horn-shaped acoustic transducer comprises a horn connected to a front cover plate of the transducer and sinusoidal steps vertically arranged on the inner side of the horn;

sinusoidal ladder sets up between the inboard adjacent vibration festival line of loudspeaker, on the loudspeaker cross-section, the nodical original point that is of preceding apron and loudspeaker generating line, and loudspeaker generating line extension line is the x axle, crosses the straight line that the original point extends to sinusoidal ladder protruding direction and be the y axle, and the surperficial sinusoidal curve of sinusoidal ladder is:

wherein, λ is the wavelength of sound wave in air, and y is the protrusion height of the sinusoidal step; a is the intersection point of a first vibration nodal line and a horn bus, b is the intersection point of a second vibration nodal line adjacent to the first vibration nodal line and the horn bus, s is a parameter, s belongs to [0,1], and x is the abscissa of any point on the sinusoidal ladder on the x axis;

the phase of any point on the sine step is pi sin (pi s).

Further limiting, the length L of the horn is 30-100 mm, the opening angle theta is 30-75 degrees, the wall thickness t is 1.8-5.4 mm, and the working frequency is 15-30 kHz.

A transduction method based on the sinusoidal stepped horn-shaped acoustic transducer specifically comprises the following steps: the piezoelectric ceramic stack to the transducer applys excitation voltage, make it produce the longitudinal vibration along the axial transmission, longitudinal vibration transmits for loudspeaker, loudspeaker make longitudinal vibration change into with loudspeaker face vertically bending vibration, confirm vibration nodal line on the vibration face of loudspeaker, the vibration phase place in vibration nodal line both sides region is opposite, set up the sinusoidal ladder between two liang of adjacent vibration nodal lines, utilize the sinusoidal ladder to make the vibration phase place of loudspeaker change, the phase place of arbitrary point is pi sin (pi s) on the sinusoidal ladder, and radiate through loudspeaker internal surface and sinusoidal step face, upwards the acoustic pressure stack in the center pin of loudspeaker, make the directive property of radiation sound field sharp-pointed, voltage emission response improves.

Further, the longitudinal vibration frequency is 15-30 kHz.

Further defined, the location of the nodal line of vibration is determined using a finite element numerical calculation method.

Further limiting, the directional main lobe 3dB beam width of the radiation sound field is 4-11 degrees; the voltage emission response TVR in air is not less than 90 dB.

The sinusoidal stepped horn-shaped acoustic transducer mainly utilizes the combination of the horn and the sinusoidal steps, utilizes the horn to convert the longitudinal vibration generated by the piezoelectric ceramic stack into the bending vibration vertical to the horn surface, utilizes the sinusoidal steps to change the vibration phase of the horn, radiates through the inner surface of the horn and the sinusoidal step surfaces, superposes the sound pressure in the central axial direction of the horn, ensures that the directivity of a radiation sound field is sharp, improves the voltage emission response, and improves the sound radiation energy by more than 10 times on the central axial; meanwhile, destructive interference of sound fields caused by opposite phases at two sides of the vibration nodal line is avoided, the size of the transducer is reduced, and application requirements of relatively high frequency and small size are met.

Drawings

Fig. 1 is a schematic structural diagram of a sinusoidal stepped horn-shaped acoustic transducer of the present invention.

Fig. 2 is a TVR curve of the voltage emission response of the sinusoidal stepped horn acoustic transducer of example 1 at the same operating frequency of 20.5 kHz.

Fig. 3 is a directivity diagram of the sinusoidal stepped horn-shaped acoustic transducer of embodiment 1 at an operating frequency of 20.5kHz as well.

Fig. 4 is a TVR curve of the voltage emission response of the composite bending vibration transducer of the comparative example at the same operating frequency of 19.9 kHz.

Fig. 5 is a directivity pattern of the composite bending vibration transducer of the comparative example at the same operating frequency of 19.9 kHz.

Detailed Description

The technical solution of the present invention will be further explained with reference to the drawings and examples, but the present invention is not limited to the following implementation cases.

Referring to fig. 1, the sinusoidal stepped horn-shaped acoustic transducer of the invention comprises a rear cover plate 1, a piezoelectric ceramic stack 2, a front cover plate 3 and a horn 4 which are sequentially arranged on the same axis, wherein the rear cover plate 1, the front cover plate 3 and the horn 4 are made of 45# steel, the rear cover plate 1, the piezoelectric ceramic stack 2 and the front cover plate 3 are fixed by bolts penetrating through a central shaft, the bottom end of the horn 4 is fixed at the front end of the front cover plate 3, the length L of the horn 4 is 30-100 mm, the opening angle theta is 30-75 degrees, the wall thickness t is 1.8-5.4 mm, and the working frequency is 15-30 kHz. A ring-shaped sinusoidal step 5 protruding inward is further provided on the inner side of the horn 4, and the sinusoidal step 5 is provided between adjacent vibration nodal lines on the inner side of the horn 4.

On the section of the horn 4, the intersection point of the front cover plate 3 and the horn 4 bus is the original point, the extension line of the horn 4 bus is the x axis, the straight line extending to the protruding direction of the sinusoidal step 5 through the original point is the y axis, and the surface sinusoidal curve of the sinusoidal step 5 is:

wherein λ is the wavelength of sound wave in air, and y is the protrusion height of the sinusoidal step 5; a is the intersection point of a first vibration nodal line and a loudspeaker 4 bus, b is the intersection point of a second vibration nodal line adjacent to the first vibration nodal line and the loudspeaker 4 bus, s is a parameter, s belongs to [0,1], and x is the abscissa of any point on the sinusoidal ladder 5 on the x axis;

the transduction method realized by the sinusoidal stepped horn-shaped acoustic transducer specifically comprises the following steps:

the method comprises the steps of applying excitation voltage to a piezoelectric ceramic stack 2 of a transducer to enable the piezoelectric ceramic stack to generate longitudinal vibration with vibration frequency transmitted along the axial direction being 15-30 kHz, enabling the longitudinal vibration to be transmitted to a loudspeaker 4, enabling the loudspeaker 4 to enable the longitudinal vibration to be converted into bending vibration perpendicular to the surface of the loudspeaker 4, determining vibration nodal lines on a vibration surface of the loudspeaker 4, enabling vibration phases of two side regions of the vibration nodal lines to be opposite, arranging a sine step 5 between every two adjacent vibration nodal lines, enabling the vibration phase of the loudspeaker 4 to be changed by utilizing the sine step 5, enabling the phase of any point on the sine step 5 to be pi sin (pi s), enabling sound pressure to be superposed upwards through the central axis of the loudspeaker 4 through radiation of the inner surface of the loudspeaker 4 and the surface of the sine step 5, enabling directivity of a radiation sound field to be sharp, improving voltage emission response and.

The radiation sound field directivity main lobe 3dB beam width of the sinusoidal stepped horn-shaped acoustic transducer is 4-11 degrees; the voltage emission response TVR in air is not less than 90 dB.

When the diameter d of the contact surface between the front cover plate 3 and the horn 4 of the transducer is 25mm, the sinusoidal stepped horn-shaped acoustic transducer of the present invention is shown in the following table 1 for each embodiment and performance parameters.

TABLE 1 examples of sinusoidal stepped horn shaped acoustic transducers and corresponding performance parameters

As can be seen from table 1 above, under the condition of no input electric power, the directivity of the whole acoustic vibration system radiating the sound field is sharper, the higher the voltage emission response is, the larger the acoustic radiation energy is, and the higher the working efficiency is.

Comparing the sinusoidal stepped horn-shaped acoustic transducer of example 1 of the present invention with the composite bending vibration transducer of the prior art (comparative example), the diameter of the contact surface of the front end of the transducer of the present invention with the horn 4 is the same as the diameter of the contact surface of the composite bending vibration transducer and the thin disk in the comparative example (d is 500mm), and the size and the number of the piezoelectric ceramic pieces of the transducers are the same, the voltage transmission response TVR of the two transducers is compared with the 3dB beam width of the main lobe, and the results are shown in table 2 below and fig. 2, 3, 4 and 5.

TABLE 2 Acoustic parameters of composite bending vibration transducers

Comparing fig. 2 and 3 with fig. 4 and 5, and combining table 2, it can be known that the directivity of the sinusoidal stepped horn-shaped acoustic transducer of the present invention is significantly improved compared with the conventional composite bending vibration transducer under the same operating frequency condition, the voltage transmission response TVR of embodiment 1 of the present invention is above 90dB, the main lobe 3dB beam width is between 4-11 °, and the composite bending vibration transducer of the comparative example has no main lobe.

Therefore, the radiation sound field directivity generated by the sinusoidal stepped horn-shaped acoustic transducer is sharper when the working frequency is the same, and the voltage emission response performance is higher on the whole.

Claims

1. a sinusoidal stepped horn-shaped acoustic transducer, is characterized in that, comprises the horn (4) that is connected on the transducer front cover plate (3) and the sine step (5) that is vertically arranged on the inner side of the horn (4);

The sinusoidal steps (5) are arranged between adjacent vibrating node lines on the inner side of the horn (4). On the section of the horn (4), the intersection of the front cover plate (3) and the busbar of the horn (4) is the origin, and the horn ( 4) The extension line of the busbar is the x-axis, the straight line extending through the origin to the protruding direction of the sine step (5) is the y-axis, and the surface sine curve of the sine step (5) is:

Among them, λ is the wavelength of the sound wave in the air, y is the protruding height of the sinusoidal step (5); a is the intersection of the first vibration node line and the busbar of the horn (4), and b is the first vibration node line adjacent to the first vibration node line. The intersection of the two vibration nodal lines and the busbar of the horn (4), s is a parameter, s∈[0,1], x is the abscissa of any point on the sine step (5) on the x-axis;

The phase of any point on the sinusoidal ladder (5) is πsin(πs).

2. The sinusoidal stepped horn-shaped acoustic transducer according to claim 1, wherein the length L of the horn (4) is 30-100 mm, the opening angle θ is 30°-75°, and the wall thickness t is 1.8 ～5.4mm, the working frequency is 15～30kHz.

3. A method for energy conversion based on the sine stepped horn-shaped acoustic transducer according to claim 1, wherein an excitation voltage is applied to the piezoelectric ceramic stack (2) of the transducer, so that it produces a transmission along the axial direction. The longitudinal vibration is transmitted to the horn (4), and the horn (4) converts the longitudinal vibration into bending vibration perpendicular to the surface of the horn (4), and the vibration node line is determined on the vibration surface of the horn (4). The vibration phases of the areas on both sides of the line are opposite. A sine step (5) is arranged between two adjacent vibration pitch lines, and the sine step (5) is used to change the vibration phase of the horn (4). The phase of any point above is πsin (πs), and it is radiated through the inner surface of the horn (4) and the surface of the sine step (5), and the sound pressure is superimposed on the central axis of the horn (4), so that the directivity of the radiated sound field is sharp, The voltage emission response is improved.

4 . The energy conversion method according to claim 3 , wherein the longitudinal vibration frequency is 15-30 kHz. 5 .

5 . The transduction method according to claim 3 , wherein the position of the vibration nodal line is determined by a finite element numerical calculation method. 6 .

6 . The method according to claim 3 , wherein the 3dB beam width of the directivity main lobe of the radiated sound field is 4-11°; the voltage emission response TVR in air is not less than 90dB. 7 .