CN111473839B

CN111473839B - Ultrasonic transducer and nested structure thereof

Info

Publication number: CN111473839B
Application number: CN202010320274.4A
Authority: CN
Inventors: 王登攀; 杨靖; 张毅; 张祖伟; 袁宇鹏; 李小飞; 梅勇
Original assignee: China Electronics Technology Group Corp Chongqing Acoustic Optic Electronic Co ltd
Current assignee: China Electronics Technology Group Corp Chongqing Acoustic Optic Electronic Co ltd
Priority date: 2020-04-22
Filing date: 2020-04-22
Publication date: 2022-02-22
Anticipated expiration: 2040-04-22
Also published as: CN111473839A

Abstract

The invention belongs to an electric and acoustic energy conversion structure, in particular to an ultrasonic transducer and a nested structure thereof; the nesting structure comprises a first filling body arranged at the bottom of the shell; a first functional body is arranged on the top of the first filling body; a second filling body protruding upwards is arranged in the middle of the upper surface of the first functional body, and a second functional body is arranged at the top of the second filling body; the first functional body adopts a low-frequency ultrasonic emission material, and the second functional body adopts a high-frequency ultrasonic emission material; the cross-sectional area of the second functional body is smaller than that of the second filling body; the cross-sectional area of the first functional body is smaller than that of the first filling body; the first filling body in the central circular area of the nested structure is smaller in thickness, and the second filling body in the peripheral circular area is larger in thickness; the first filling body uses a piezoelectric sheet which is transmitted and received by high frequency as an exciting element, and the second filling body uses a piezoelectric wafer or a piezoelectric ring with lower frequency as an exciting element, so that the dual-frequency point operation is realized.

Description

Ultrasonic transducer and nested structure thereof

Technical Field

The invention belongs to an electric and acoustic energy conversion structure, and particularly belongs to an ultrasonic transducer and a nested structure thereof.

Background

Ultrasonic level gauges are the fastest growing class of gauges in non-contact measurements. The distance measurement is realized based on the principle that ultrasonic waves generate reflection on the surface of a measured object and the function relation between the measured distance and time. The ultrasonic liquid level meter has the advantages of wide measurement range, no influence of medium density and dielectric constant on measurement and the like, is suitable for various measurement media such as gas, liquid or solid, has wide application range, comprises various different occasions such as a water channel, an oil tank, an air tank and the like, and can also be applied to liquid level measurement such as viscous, corrosive and toxic liquid.

Chinese patent "an ultrasonic wave level gauge improved oscillator structure" (201721392541.9) has proposed an ultrasonic transducer structure that can improve the gauge blind area, through increasing a layer and strengthening the back of the body and weighing the glue, the purpose is to improve the absorption efficiency of the backward sound wave, reduce its influence to the blind area. However, since the ultrasonic transducer has its inherent transient characteristic, it usually needs a plurality of driving pulses to achieve stable signal output, and therefore, the improvement effect of the dead zone is limited only by accelerating the attenuation of the trailing signal.

The blind area and the acting distance of the ultrasonic liquid level meter are closely related to the working frequency, and generally speaking, the blind area and the acting distance of the liquid level meter are small when the liquid level meter works at high frequency; when the liquid level meter works at a low frequency, the dead zone of the liquid level meter is large, and the acting distance is large. The ultrasonic liquid level meter working at a single frequency point can give consideration to certain blind areas and action distances simultaneously through optimized design, but cannot realize small blind areas and large action distances simultaneously, so that an ultrasonic transducer working at multiple frequency points needs to be developed.

Disclosure of Invention

Aiming at the requirements, the patent aims at improving the measurement range and the blind area of the ultrasonic liquid level meter and provides an ultrasonic transducer with multi-frequency-point operation and a nested structure thereof. The multi-frequency point design is based on the following purposes that when the liquid level is low, a high-frequency point is utilized to work, the period of high-frequency ultrasonic waves is short, the attenuation speed is high, the blind area can be effectively reduced, and the measurement precision can be improved; when the measuring system needs to work in a large range, the measuring system can work in a low-frequency band, the low-frequency ultrasonic wave penetration capacity is high, the attenuation in the transmission process is small, the transmission distance is longer under the excitation of the same voltage, and the liquid level measurement in the large range is favorably realized. The structure can be used for an embedded water level meter and the like, and is used for liquid level measurement of a water channel, a road surface, a river and the like; the ultrasonic liquid level meter can also be used for other ultrasonic liquid level meters and is used for liquid level measurement of storage tanks, containers and the like.

In a first aspect of the invention, the invention proposes a nested structure of ultrasound transducers; the device comprises a shell, wherein a first filling body is arranged at the bottom of the shell; a first functional body is arranged on the top of the first filling body; a second filling body protruding upwards is arranged in the middle of the upper surface of the first functional body, and a second functional body is arranged at the top of the second filling body; the first functional body is made of a low-frequency ultrasonic emission material, and the second functional body is made of a high-frequency ultrasonic emission material; wherein the cross-sectional area of the second functional body is smaller than that of the second filling body; the cross-sectional area of the first functional body is smaller than that of the first filling body.

In a second aspect of the invention, the invention also provides an ultrasonic transducer comprising a substrate, the nested structure is mounted on the bottom of the substrate.

The invention has the beneficial effects that:

the thickness of the first filling body in the circular area in the center of the shell cover plate of the nested structure is smaller, and the thickness of the second filling body in the peripheral circular area is larger. The first filling body uses a piezoelectric sheet which is transmitted and received by high frequency as an exciting element, and the second filling body uses a piezoelectric wafer or a piezoelectric ring with lower frequency as an exciting element, thereby realizing double-frequency-point work. The nested structure of the invention can be further expanded to a 3-layer or more nested structure; when the liquid level is low, the high-frequency point is utilized to work, the high-frequency ultrasonic wave period is short, the attenuation speed is high, the blind area can be effectively reduced, and the measurement precision can be improved; when the measuring system needs to work in a large range, the measuring system can work in a low-frequency band, the low-frequency ultrasonic wave penetration capacity is high, the attenuation in the transmission process is small, the transmission distance is longer under the excitation of the same voltage, and the liquid level measurement in the large range is favorably realized. The structure can be used for an embedded water level meter and the like, and is used for liquid level measurement of a water channel, a road surface, a river and the like; the ultrasonic liquid level meter can also be used for other ultrasonic liquid level meters and is used for liquid level measurement of storage tanks, containers and the like.

Drawings

FIG. 1 is a schematic view of the installation and application of a buried water level gauge;

FIG. 2 is a nested configuration of piezoelectric wafers of the present invention;

FIG. 3 is a nested configuration of piezoelectric rings of the present invention;

FIG. 4 is a nested configuration of a concave cover plate of the present invention;

FIG. 5 is a nested configuration of a male cover plate of the present invention;

FIG. 6 is a nested configuration of the invention in the form of a truncated cone;

FIG. 7 is an inverted frustum-shaped nesting feature of the present invention;

FIG. 8 is a nested configuration of a piezoelectric ceramic of the present invention;

FIG. 9 is a nested configuration of a piezoelectric composite of the present invention;

FIG. 10 is a nested configuration using piezoelectric composites;

FIG. 11 is a nested configuration of flat plate shells;

FIG. 12 shows the structure of the piezoelectric composite material used for each of the first functional bodies according to the present invention;

FIG. 13 is an ultrasonic transducer of the present invention;

in the figure, 11, liquid, 12, substrate, 13, cavity, 14, ultrasonic transducer, 15, filling body, 16, transmitting ultrasonic wave, 17, receiving echo, 18 and liquid level; 21. 31, 41, 51, 61, 71, 81, 91, 101, 131 are shells, 22, 32, 42, 52, 62, 72, 82, 92, 102 are first fillers, 23, 33, 43, 53, 63, 73, 83, 93, 103, 113, 133 are first functional bodies, 24, 34, 44, 54, 64, 74, 84, 94, 104, 114, 134 are second functional bodies, 25, 85, 95, 105, 112, 145 are second fillers; 86. 96, 98, 106, 108, 116, 118, 122, 124, 135, 136 are slots; 111. the protective layer 121, the piezoelectric

ceramic block body

87, 97, 99, 107, 109, 115, 117, 123, 125 are piezoelectric columns, 132 is a back-weighing layer, 137 is decoupling material, 138 is a conducting wire, 139 is sound-absorbing sealing material, 140 is a connector, 141, 142, 143, 144 are electrodes, 146 is a cover plate, and 147, 148 are matching layers.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly and completely apparent, the technical solutions in the embodiments of the present invention are described below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

In general, a conventional embedded ultrasonic level meter is used as shown in fig. 1, wherein a liquid 11 is located below a liquid level 18, and a receiving echo 17 and a transmitting ultrasonic wave 16 are transmitted in the liquid 11; a substrate 12 is arranged below the liquid 11, an ultrasonic transducer structure is arranged on the top of the substrate 12, the ultrasonic transducer structure comprises a shell, a cavity 13 is arranged on the top of the shell, an ultrasonic transducer 14 is arranged below the cavity 13, and a filling material 15 covers the periphery of the ultrasonic transducer 14; in order to improve the pressure resistance of the whole structure, the cavity 13 can be made of high-strength plastic or metal with a certain thickness. For a certain pressure intensity, the larger the area of the cover plate is, the larger the deformation of the central position is, and the more easily the stress intensity limit is exceeded. For a cover plate with a certain thickness, low-frequency ultrasonic waves are easier to penetrate, and the loss is smaller; the high-frequency ultrasonic wave is blocked by the cover plate more easily, and the loss is larger.

The invention provides a nesting structure of an ultrasonic transducer, wherein the thickness of a circular area in the center of a cover plate is smaller, and the thickness of a circular area on the periphery of the cover plate is larger. The central area uses a piezoelectric sheet which is transmitted and received at high frequency as an exciting element, and the peripheral ring area uses a piezoelectric wafer or a piezoelectric ring with lower frequency as an exciting element, so that the double-frequency-point work is realized. The structure can be further extended to a nested structure of 3 layers or more. Specific embodiments of the present invention are described below in conjunction with specific embodiments.

Example 1

The invention provides a nested structure of piezoelectric wafers, the cross section structure of which is shown in fig. 2, the nested structure of the piezoelectric wafers comprises a shell 21, wherein a cylindrical first filling body 22 is arranged at the bottom of the shell 21; a first functional body 23 is mounted on the top of the first filling body 22; a second filling body 25 protruding upwards is arranged in the middle of the upper surface of the first functional body 23, and a second functional body 24 is arranged on the top of the second filling body 25; in the nested structure, the first functional body 23 adopts a piezoelectric wafer with lower frequency; the second functional body 25 adopts a piezoelectric sheet which is transmitted and received at high frequency, and the piezoelectric wafer and the piezoelectric sheet are both in cylindrical structures; the thickness of the piezoelectric wafer is larger than that of the piezoelectric sheet, and the radius of the piezoelectric wafer is larger than that of the piezoelectric sheet. In the nested structure, the first functional body 23 works in a low-frequency band, the second functional body 24 works in a high-frequency band, the blind area of the liquid level meter is smaller than that of the first functional body 23 when the second functional body 24 is excited, and the second functional body 24 is excited to work when the blind area is smaller; when a large measuring range is required, the first functional body 23 is activated to operate.

Example 2

On the basis of the embodiment 1, the invention provides a nesting structure of piezoelectric rings, the cross-sectional structure of which is shown in fig. 3, the nesting structure of the piezoelectric rings comprises a shell 31, and a first filling body 32 in a convex shape is arranged at the bottom of the shell 31; annular first functional bodies 33 are arranged on the tops of two shoulders of the first filling body 32; a second functional body 34 is provided on the upper top of the first filling body 32; in the nested structure, the annular first functional body 32 is a piezoelectric ring with lower frequency; the second functional body adopts a piezoelectric sheet which receives and transmits at high frequency; just because the first functional body 32 adopts the piezoelectric ring structure, so that the first functional body 33 is not directly contacted with the second filling body, the second filling body 24 and the first filling body 23 in embodiment 1 are combined to form the convex first filling body 32 in this embodiment; similarly, the thickness of the piezoelectric ring is larger than that of the piezoelectric sheet, and the ring diameter of the piezoelectric ring is larger than that of the piezoelectric sheet; in the present invention, the piezoelectric wafer of the first functional body 32 in example 1 is replaced with a piezoelectric ring, and different directivities can be obtained.

Example 3

On the basis of embodiment 2, the invention provides a concave cover plate nesting structure, the cross-sectional structure of which is shown in fig. 4, the annular column nesting structure comprises a concave shell 41, namely, the cover plate of the shell 41 is a concave cover plate, and a convex first filling body 42 is arranged at the bottom of the shell 41; annular first functional bodies 43 are arranged on the tops of two shoulders of the first filling body 42; a second functional body 44 is provided on the upper top of the first filling body 42; in the embodiment, the concave cover plate is adopted to focus the wave beam, so that the wave beam with a narrower structure than that in the embodiment 2 can be obtained, the acoustic energy is focused more, and the detection distance is longer.

Example 4

On the basis of embodiment 2, the invention provides a concave cover plate nesting structure, the cross-sectional structure of which is shown in fig. 5, the annular cylindrical nesting structure comprises a shell 51 which is convex upwards, namely the cover plate of the shell 51 is a concave cover plate, and a convex first filling body 52 is arranged at the bottom of the shell 51; annular first functional bodies 53 are arranged on the tops of two shoulders of the first filling body 52; a second functional body 54 is provided on the upper top of the first filling body 52; the convex cover plate is adopted in the embodiment, so that the beam width is larger, the sound energy is more dispersed, and the echoes of the liquid level and impurities can be distinguished by the wide beam under the condition of some special applications, such as when large-volume impurities exist in liquid.

Example 5

On the basis of embodiment 2, the invention provides a truncated cone-shaped nesting structure, the cross-sectional structure of which is shown in fig. 6, the truncated cone-shaped nesting structure comprises a shell 61, a first filling body 62 which is convex and two shoulders of the convex are truncated cone-shaped is arranged at the bottom of the shell 61; annular first functional bodies 63 with an inverted circular table shape are mounted at the tops of two shoulders of the first filling body 62, the annular first functional bodies 63 are perpendicular to the circular table surface of the first filling body 62, and the inclination angles of the first functional bodies 63 and the first filling body 62 are consistent; that is, the rounded mesa of the first functional body 63 exactly fits the rounded mesa of the first filling body 62; a second functional body 64 is provided on the upper top of the first filling body 62; the directivity of the low-frequency ultrasonic transceiving is changed by changing the driving direction of the first functional body 63, namely the functional material for the low-frequency ultrasonic transceiving, so as to adapt to different application requirements.

Example 5

On the basis of the embodiment 2, the invention provides another inverted frustum-shaped nesting structure, the cross-sectional structure of which is shown in fig. 7, the inverted frustum-shaped nesting structure comprises a shell 71, and a first filling body 72 which is raised and two shoulders of the projection are inverted frustum-shaped is installed at the bottom of the shell 71; the top parts of two shoulders of the first filling body 72 are provided with circular first functional bodies 73 with circular table surfaces, the circular first functional bodies 73 are vertical to the circular table surfaces of the first filling body 72, and the angles of the slope surfaces are consistent with those of the first filling body 72; that is, the circular table of the first functional body 73 exactly fits the rounded table of the first filling body 72; a second functional body 74 is arranged on the upper top of the first filling body 72; the driving direction of the first functional body 73, that is, the functional material for low-frequency ultrasonic transceiving is changed, so that the directivity of low-frequency ultrasonic transceiving is changed to adapt to different application requirements.

Example 6

In addition to embodiment 1, the present invention provides a nested structure of piezoelectric ceramics, a cross-sectional structure and a cross-sectional view of which are shown in fig. 8 to 10, and a cross section of each of the first functional body 83, the second functional body 94, and the first functional body 103 is a cross section;

in FIG. 8; the nesting structure comprises a shell 81, and a cylindrical first filling body 82 is arranged at the bottom of the shell 81; a first functional body 83 is arranged on the top of the first filling body 82, and the first functional body 83 comprises a plurality of piezoelectric columns 87; a second filling body 85 is provided above the first functional body 83; a second functional body 84 is arranged on the top of the second filling body 85; the material of the second functional body 84 can be selected from piezoelectric ceramics, piezoelectric crystals, piezoelectric polymers and other materials; wherein, the second functional body 84 adopts a complete piezoelectric ceramic block body without a cutting seam; the piezoelectric column 87 of the first functional body 83 can be made of piezoelectric ceramics, piezoelectric crystals, etc.; since the piezoelectric pillars 87 have the gaps 86 therebetween, the gaps 86 may be filled with a filler material or may be formed as voids.

In fig. 9, the nesting structure comprises a shell 91, and a first cylindrical filling body 92 is arranged at the bottom of the shell 91; a first functional body 93 is mounted on the top of the first packing body 92, and the first functional body 93 has a spatial structure formed by a plurality of piezoelectric columns 97 and slits 96; a second filling body 95 is provided above the first functional body 93; a second functional body 94 is arranged on the top of the second filling body 95; the second functional body 94 is a space structure formed by a plurality of piezoelectric columns 99 and gaps 98, and the gaps 96 and the gaps 98 can be filled with filling materials or in a gap mode; the piezoelectric columns of the first functional body 93 and the second functional body 94 are made of piezoelectric composite materials.

Fig. 10 is the same nested structure as fig. 9, except that the cross section is different, and the nested structure in fig. 10 comprises a shell 101, and a first cylindrical filling body 102 is arranged at the bottom of the shell 101; a first functional body 103 is arranged on the top of the first filling body 102, and the first functional body 103 is a space structure consisting of a plurality of piezoelectric columns 107 and slits 106; a second filling body 105 is arranged above the first functional body 103; a second functional body 104 is arranged on the top of the second filling body 105; the second functional body 104 is a space structure formed by a plurality of piezoelectric columns 109 and slits 108, and the slits 106 and the slits 108 can be filled with a filling material or in a void mode; piezoelectric columns of the first functional body 103 and the second functional body 104 are both made of piezoelectric composite materials, and this embodiment provides structures of different functional bodies, and in fig. 8, the first functional body is a piezoelectric ceramic block, and the second functional body is made of piezoelectric composite materials; in fig. 9 and 10, the first functional body and the second functional body are both piezoelectric composite materials; of course, the first functional body may be a piezoelectric composite material, and the second functional body may be a piezoelectric ceramic block.

Example 7

On the basis of the above embodiments, the present embodiment provides a nesting structure of a flat shell, as shown in fig. 11, the shell in fig. 8 to 10 is changed into a flat protective layer 111, which may be a directly processed circular plate or a protective layer formed by casting and curing a liquid material, and typical materials thereof may be polyurethane sound-transmitting rubber, epoxy resin potting adhesive, neoprene rubber, and the like; a second filling body 112 is arranged below the protective layer 111, and a second functional body 114 is arranged on the top of the second filling body 112; wherein the second functional body 114 is in the form of a piezoelectric column 115 and a slit 118; a first functional body 113 is installed below the second filling body 112, and the first functional body 113 exists in the form of a piezoelectric column 117 and a slit 116; and gap 118 and gap 116 may be a filler material or a void. The selection and implementation of the materials such as the filling material, the piezoelectric column and the gap are similar to those in the structures of fig. 8-10.

Example 8

FIG. 12 shows a first functional body corresponding to various manufacturing methods of piezoelectric composite materials; the functional material that can be used for the first

functional bodies

33, 43, 53, 63, 73 in fig. 3 to 7 may be in the form of a piezoelectric ceramic block 121 of a piezoelectric ring, and may also be in the form of a piezoelectric composite material, for example, a 1-3 type piezoelectric composite material, and two combinations of

piezoelectric columns

123, 125 and slits 122, 124 are shown.

Example 9

This embodiment provides an ultrasonic transducer, as shown in fig. 13, including a housing 131 and a cover plate 146, wherein a material structure is installed inside the housing 131; the material structure is provided with a backing layer 132, a decoupling material 137 is provided outside the backing layer 132, a plurality of

electrodes

141, 142, 143, 144 are provided on the material structure and are connected to the outside through a lead 138, the material structure is coated with a sound-absorbing sealing material 139, and a connector 140 is provided outside a cover plate 146.

For the sake of convenience, fig. 13 mainly includes the case of the filler and the gaps around the piezoelectric pillars in the functional body; the non-illustrated portions may refer to other embodiments or other figures; in the present embodiment, the material structure includes a second filling body 145, a first functional body 133 and a second functional body 134, wherein 135 is a gap in the second

functional body

134, 136 is a gap in the first functional body 133, that is, a corresponding filling material or a gap in the functional body, the second filling body 145 may be a filling material or a gap, and a

matching layer

147, 148 is installed above each functional body.

Wherein the material arrangement forms together with the housing and the cover plate the nested structure of the invention.

In another embodiment, this embodiment also shows a dimensioning of fig. 13: the structure comprises two functional elements of high-frequency and low-frequency piezoelectric composite materials, wherein the high-frequency piezoelectric composite material realizes the transceiving of high-frequency ultrasonic waves, and the low-frequency piezoelectric composite material realizes the transceiving of low-frequency ultrasonic waves. Assuming that the high operating frequency is f1 and the low operating frequency is f2, the thicknesses of the different parts of the housing need to match the 2 frequencies described above, where thickness d1 is an integer multiple of the half wavelength (c1/(2 f1)) of the housing material (speed of sound c1) at f1, thickness d2 is an integer multiple of the half wavelength (c1/(2 f2)) of the housing material (speed of sound c1) at f2, thickness d3 is a quarter wavelength (c2/(4 f1)) of the matching layer material (speed of sound c2) at f1), and thickness d4 is a quarter wavelength (c3/(4 f2)) of the matching layer material (speed of sound c3) at f 2).

The working mode of the low-frequency piezoelectric composite material is basically the same as that of the high-frequency piezoelectric composite material, alternating voltage is applied through the

electrodes

143 and 143 to cause the low-frequency piezoelectric composite material to vibrate, and a part of vibration signals penetrate through the matching layer 148, the filling material 145, the high-frequency piezoelectric composite material, the matching layer 147 and the part with the thickness d1 in the shell 131 to reach the liquid medium; since a part of the vibration signal passes through the matching layer 148 and the housing to reach the liquid medium, the materials of the filling material 145, the housing 131, and the matching layers 147 and 148 need to be optimally designed according to different beam requirements, so that the receiving and transmitting of the low-frequency signal can achieve the best effect.

For similar structures, the material selection of the structure in fig. 13 is the same as that in fig. 8 to 11, and the

electrodes

141, 142, 143, 144, etc. can be selected from various metal materials such as gold, silver, copper, aluminum, etc.; the matching layers 147 and 148 can be made of various materials such as rigid polyurethane foam, glass beads and epoxy resin, alumina powder and epoxy resin; the decoupling layer 137 can be made of cork rubber, cork particles and polyurethane rubber; 139 is a sound-absorbing sealing material, which can be a mixture of polyurethane, epoxy resin, cork particles, glass beads, tungsten powder, etc. The material selection is only a reference combination, and other forms can be adopted according to actual conditions.

In the invention, the shell mainly plays roles of fixing, supporting and protecting, and can be made of metal or high-strength plastic; the filling material has the main functions of sound absorption, water tightness, protection and the like, can be selected from pouring sealants such as polyurethane, epoxy resin and the like, and can also be added with filling materials such as cork particles, glass beads and the like; the gap can be a space formed by cutting the piezoelectric ceramic block body without filling any material, or a space formed by the piezoelectric column and the shell without filling any material after the piezoelectric wafer (ring) is arranged in the shell.

Those skilled in the art will appreciate that all or part of the steps in the methods of the above embodiments may be implemented by associated hardware instructed by a program, which may be stored in a computer-readable storage medium, and the storage medium may include: ROM, RAM, magnetic or optical disks, and the like.

The above-mentioned embodiments, which further illustrate the objects, technical solutions and advantages of the present invention, should be understood that the above-mentioned embodiments are only preferred embodiments of the present invention, and should not be construed as limiting the present invention, and any modifications, equivalents, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The nesting structure of the ultrasonic transducer is suitable for an ultrasonic liquid level meter and comprises a shell, and is characterized in that a first filling body is arranged at the bottom of the shell; a first functional body is arranged on the top of the first filling body; a second filling body protruding upwards is arranged in the middle of the upper surface of the first functional body, and a second functional body is arranged at the top of the second filling body; the first functional body is made of a low-frequency ultrasonic emission material, and the second functional body is made of a high-frequency ultrasonic emission material; wherein the cross-sectional area of the second functional body is smaller than that of the second filling body; the cross-sectional area of the first functional body is smaller than that of the first filling body.

2. The nested structure of ultrasonic transducers of claim 1, wherein the first functional body is a piezoelectric wafer or a piezoelectric ring.

3. The nesting structure of ultrasonic transducers of claim 2, wherein the thickness of the first functional body is greater than the thickness of the second functional body.

4. The nesting structure of ultrasonic transducers of claim 3, wherein the upper surface of the first filling body is a circular table or a rounded table with a certain inclination angle.

5. The nesting structure of ultrasonic transducers of claim 4, wherein the first functional body is a circular truncated cone or a circular cylinder with the same inclination angle as the first filling body.

6. The nesting structure of ultrasonic transducers of claim 1, wherein the top of the housing is a planar cover, a concave cover, or a convex cover.

7. The nested structure of ultrasonic transducers according to claim 1, wherein the first functional body is a piezoelectric composite material or a piezoelectric ceramic block.

8. The nested structure of ultrasonic transducers of claim 1, wherein the second functional body is a piezoelectric composite material or a piezoelectric ceramic block.

9. An ultrasonic transducer comprising a substrate, characterized in that a nesting structure comprising any of claims 1-8 is mounted on top of the substrate.

10. The ultrasonic transducer of claim 9, further comprising a backing layer mounted on the nesting structure, a decoupling material disposed outside the backing layer, a plurality of electrodes disposed on the nesting structure and connected outward by wires, a sound absorbing sealing material coated on the nesting structure, and a connector disposed outside the cover plate.