WO2022048058A1

WO2022048058A1 - High-power high-frequency directional transmission underwater acoustic transducer and manufacturing method therefor

Info

Publication number: WO2022048058A1
Application number: PCT/CN2020/133855
Authority: WO
Inventors: 秦雷; 仲超; 王丽坤
Original assignee: 北京信息科技大学
Priority date: 2020-09-04
Filing date: 2020-12-04
Publication date: 2022-03-10
Also published as: EP4173728A4; CN112221917A; EP4173728A1; CN112221917B

Abstract

A high-power high-frequency directional transmission underwater acoustic transducer and a manufacturing method therefor. The transmission underwater acoustic transducer comprises a piezoelectric composite, electrodes, a matching layer, a heat dissipation structure, and an acoustic backing; the piezoelectric composite is a 1-1-3 type piezoelectric composite and consists of a piezoelectric phase, a passive phase and a structural phase, the piezoelectric phase is an array of piezoelectric material columns, the structural phase is a rigid material frame between the piezoelectric material columns, and the passive phase is a flexible polymer between the piezoelectric phase and the structural phase; the heat dissipation structure is a rigid material frame having the same structural phase as that of the piezoelectric composite; and the acoustic backing is distributed in the heat dissipation structure. A piezoelectric material having low loss and high pressure resistance and a 1-1-3 type piezoelectric composite structure are used to design the transmission transducer having the characteristics of high frequency, high directivity, high power, low loss and fast heat dissipation, achieving continuous transmission of directional energy through sound waves within a distance of 10 m in a marine environment.

Description

High-power high-frequency directional emission underwater acoustic transducer and preparation method thereof

technical field

The invention belongs to the technical field of piezoelectric transducers, and in particular relates to a high-frequency underwater acoustic transducer with high-power directional emission acoustic wave characteristics based on piezoelectric composite materials and a preparation method thereof.

Background technique

With the development of Underwater Unmanned Vehicle (Unmanned Undersea Vehicle, UUV) and underwater sensor network, the point energy supply mode of these devices requires higher and higher degree of automation and long-distance transmission. Traditional salvage charging and electromagnetic underwater wireless charging have the characteristics of high charging efficiency, but they are difficult to operate and the charging distance is only a few millimeters, which limits most applications.

In recent years, the wireless transmission technology of underwater electric power has received extensive attention all over the world. This charging method is free from the shackles of lengthy wires and can be independently packaged, improving reliability, mobility and concealment. At present, there are two main methods of underwater wireless power transmission technology: electromagnetic and ultrasonic, which transmit energy through electromagnetic fields and sound waves respectively. We know that seawater has good electrical conductivity and high electrical conductivity, so high-frequency alternating magnetic fields will generate eddy current losses in seawater and affect transmission efficiency. In addition, this method of transmitting energy through electromagnetic field has a large limitation on the action distance, and usually the charging should be kept within the order of millimeters. Therefore, during the underwater charging process, the precise docking of the charger and the current collector should be ensured first, that is, the consumption of time cost is high. For small-sized underwater sensor network nodes, the operability is poor, and this method is only suitable for large-scale underwater fixed charging stations to charge large-scale UUVs and other equipment with high-power 100W to kW. In the case of ensuring charging efficiency, the acoustic energy power supply method has no underwater interface and can realize long-distance charging without complex operations such as precise positioning. It is a potential optimal solution for wireless power supply for small UUV and underwater sensor network nodes. plan.

The biggest advantage of underwater sonic wireless charging is the long underwater transmission distance. Compared with electromagnetic induction, this method does not generate electromagnetic interference to the outside world, nor is it affected by electromagnetic interference, and its wavelength is much smaller than that of electromagnetic waves, with good transmission direction and easier energy concentration. The current research status shows that underwater sonic wireless charging can be realized at a distance of 6cm, which reveals that sonic wireless charging is feasible, but the transmission power is small and the action distance is short, and there are still many technical difficulties to be overcome. This is because researchers generally ignore the influence of the underwater acoustic transceiver as a sound wave conversion device on the charging effect. First of all, researchers generally use the same transducer as the transmitting and receiving ends, and do not play the respective characteristics of the transmitting transducer and the receiving transducer, resulting in energy loss. Second, researchers generally ignore the scattering loss of sound waves during transmission, which makes charging inefficient. Moreover, there are relatively few studies on the energy conversion efficiency of the transducer, the heat dissipation of the transmitting transducer, the acoustic matching between the transducer and the water, and the focusing of acoustic energy.

Therefore, how to realize the design of high-frequency and high-power directional underwater acoustic transducer and how to solve the heat dissipation problem when the transducer works continuously and high-power are the key issues in the future research on underwater acoustic wave wireless charging. We know that the purpose of the traditional underwater acoustic transducer design is to maximize the detection distance and the spatial range of detection. The underwater acoustic transducer focuses on the characteristics of low frequency and large beam opening angle. This transducer design allows the sound wave energy to spread out into a larger space. Therefore, the achievable energy transfer efficiency of the underwater acoustic wave wireless charging device designed relying on the traditional transducer is bound to be lower with the increase of the acoustic wave transmission distance. On the other hand, in the application background of sonar and underwater acoustic communication, the underwater acoustic transducer usually works under the condition of pulse excitation (for example, the pulse duty ratio is 2%), and the heat generated by the loss can be dissipated in time. Usually no special thermal design is necessary. In the field of underwater charging, the transmitting transducer is required to work continuously with high power, and heat dissipation design has become an inevitable core key issue.

SUMMARY OF THE INVENTION

In order to achieve high-power continuous directional propagation of underwater acoustic energy, it can meet the needs of wireless long-distance power supply for underwater unmanned vehicles and underwater sensor networks. The invention adopts piezoelectric materials such as piezoelectric ceramics with low loss and high voltage resistance characteristics, and combines the 1-1-3 piezoelectric composite structure to design a piezoelectric material with the characteristics of high frequency, high directivity, high power, low loss and fast heat dissipation. Transmitters.

The technical scheme adopted in the present invention is as follows:

A high-power high-frequency directional emission underwater acoustic transducer, comprising a piezoelectric composite material, an electrode, a matching layer, a heat dissipation structure, and a sound-absorbing backing; the piezoelectric composite material is a 1-1-3 type piezoelectric composite material , consisting of a piezoelectric phase, a passive phase and a structural phase, the piezoelectric phase is an array of piezoelectric material columns, the structural phase is a rigid material frame located between the piezoelectric material columns, and the passive phase is located between the piezoelectric phase and the structural phase The piezoelectric composite material covers the electrodes on both surfaces in the thickness direction; the matching layer is located on one side of the piezoelectric composite material, and the heat dissipation structure and the sound-absorbing backing are located on the other side of the piezoelectric composite material; the heat dissipation structure is the same rigid material frame as the structure in the piezoelectric composite material; the sound absorbing backing is distributed in the heat dissipation structure.

Further, the heat dissipation structure and the heat dissipation structure (ie the structural phase) contained in the piezoelectric composite material have the same material and structure size; the heat dissipation structure and the heat dissipation structure (ie the structural phase) contained in the piezoelectric composite material are precise to each other. matched for good heat transfer.

Further, it also includes a casing and a cable. The shell is a metal shell, and the heat dissipation structure is closely connected with the metal shell to achieve good heat transfer. The cables connect leads on the electrodes.

Further, the piezoelectric phase material in the piezoelectric composite material is composed of low-loss piezoelectric ceramics or piezoelectric crystals, which may be piezoelectric ceramics, piezoelectric crystals, and the like.

Further, the passive phase material in the piezoelectric composite material is made of high temperature resistant flexible polymer, which can be polyphenylene, parylene, polyarylene ether, polyarylate, aromatic polyamide, polyamide. Amine, silicone rubber, etc.

Further, the structural phase material in the piezoelectric composite material is selected from materials with good heat dissipation characteristics and prepared into a grid structure by machining, which can be carbon fiber composite materials or low-density metal materials such as aluminum and titanium alloys.

Further, the matching layer is a trapezoidal matching layer, and the lower bottom surface of each trapezoid of the trapezoidal matching layer is opposite to the upper surface of the piezoelectric material column in the piezoelectric composite material.

A method for preparing the above-mentioned high-power high-frequency directional emission underwater acoustic transducer, comprising the following steps:

1) Cutting a whole piece of piezoelectric material into a periodically arranged piezoelectric material column array;

2) The processed rigid material frame is placed between the piezoelectric material column arrays, and the passive phase material is poured into the gap between the rigid material frame and the piezoelectric material column, and cured;

3) Grinding the upper and lower surfaces to the required thickness, and preparing metal electrodes on the upper and lower surfaces to form a 1-1-3 piezoelectric composite material;

4) Weld the wires on the upper and lower electrode surfaces of the 1-1-3 piezoelectric composite material;

5) Adhere to each other the heat dissipation structure formed by the lower electrode surface of the 1-1-3 piezoelectric composite material and the rigid material frame, and keep the rigid material frame and the rigid material frame inside the 1-1-3 piezoelectric composite material to match each other ;

6) The sound-absorbing backing material is poured or bonded in the heat dissipation structure composed of the rigid material frame, and cured;

7) Adhere the processed trapezoidal matching layer on the electrode surface of the 1-1-3 type piezoelectric composite material, and keep the lower bottom surface of each trapezoid facing the upper surface of the piezoelectric material column;

8) Assemble the structure obtained in step 7) with the structural parts, and weld the wire and the watertight cable;

9) Place the structure obtained in step 8) in a mold, pour a waterproof sound-permeable layer, and complete the transducer fabrication after curing.

An array of emitting underwater acoustic transducers includes at least two high-power high-frequency directional emitting underwater acoustic transducers as described above.

The beneficial effects of the present invention are as follows:

Aiming at the demand for wireless power supply of underwater unmanned vehicles and sensor network nodes, the invention applies piezoelectric ceramics with low loss and high voltage resistance characteristics, and combines 1-1-3 piezoelectric composite structure design with high frequency and high directivity Transmitter type transducer with characteristics of high performance, high power, low loss and fast heat dissipation. Finally, in the marine environment, within a distance of 10m, continuous transmission of directional energy through sound waves is achieved.

The invention extends the research of loss and heat dissipation to the research field of piezoelectric composite materials and transducers for the first time. Starting from the research of low-loss piezoelectric materials, the heat dissipation structure was introduced into piezoelectric composite materials, and expanded to the transducer structure, and the design scheme of high-power, continuous-working underwater acoustic emission transducer was explored. The research and development of this new type of underwater acoustic emission transducer can also change the application mode of traditional high-frequency sonar, and open up new application fields such as underwater directional communication and underwater acoustic fuze.

Description of drawings

Figure 1 is a schematic structural diagram of a high-power, directional underwater acoustic emission transducer.

Figure 2 is a schematic diagram of the structure of the 1-1-3 type composite material. (a) is a perspective view, and (b) is a plan view.

Figure 3 is a graph of underwater acoustic performance of a directional underwater acoustic emission transducer, in which (a) is the emission voltage response curve of sample A, (b) is the emission voltage response curve of sample B, and (c) is the sound source of samples A and B order curve, (d) is the directivity curve of samples A and B.

FIG. 4 is a schematic diagram of the near-field acoustic radiation characteristics of the transmitting transducer.

detailed description

In order to make the above objects, features and advantages of the present invention more clearly understood, the present invention will be further described in detail below through specific embodiments and accompanying drawings.

The structure of the high-power, directional underwater acoustic emission transducer of this embodiment is shown in FIG. 1, including piezoelectric composite material, matching layer, heat dissipation structure, sound-absorbing backing, waterproof sound-transmitting layer, and shell. Among them, the piezoelectric composite material is a large-size 1-1-3 piezoelectric composite material prepared by a cutting-infusion process, so as to realize the advantages of high-power transducer and directional emission of sound waves. The electrode of the piezoelectric composite material (the electrode is not shown in FIG. 1 ) adopts a low-temperature curing silver paste, which satisfies high solderability and high firmness at the same time. A trapezoidal matching layer as shown in Figure 1 is used to achieve both acoustic impedance matching and displacement amplification.

The traditional transducer adopts the form of pulse excitation and works in the underwater environment, so the traditional transducer does not use the heat dissipation structure. However, in the present invention, since the transmitting transducer works under high power and adopts the form of continuous sine wave excitation, it is necessary to introduce a heat dissipation structure into the structural member as a heat dissipation mechanism in the composite material (that is, the third phase in the piezoelectric composite material is composed of The frame type heat dissipation structure) extension, so as to achieve further heat dissipation. The heat dissipation structure has the same material and structure as the third phase material in the 1-1-3 piezoelectric composite material, and a high acoustic impedance epoxy resin tungsten powder mixture is added in the pores of the heat dissipation structure as the backing sound-absorbing material. Constructs sound absorbing backing.

The 1-1-3 type composite material structure of this embodiment is shown in Figure 2. The piezoelectric column (the first phase material, also called the piezoelectric phase) is one-dimensionally connected in the z direction, and a surrounding layer is also only in the z direction. The flexible polymer (the second phase material, also known as the passive phase) is connected in the direction, while the rigid material (the third phase material, also known as the structural phase) is connected in the three directions of x, y, and z, acting as a lateral support effect. The conversion between vibration energy and electrical energy is realized by the longitudinal stretching mode of the first phase material in the 1-1-3 piezoelectric composite material; the low Young's modulus of the second phase material in the piezoelectric composite material is used to make the pressure The electric column works in an approximate free vibration state, which further improves the energy conversion efficiency. At the same time, the rubber with high thermal conductivity is selected to realize the timely dissipation of the heat generated by the piezoelectric column and the interface. Young's modulus is used to achieve the mechanical stability of the composite material, and carbon fiber or low-density metal material with high thermal conductivity is selected as the third phase material to achieve further heat dissipation. By adjusting the ratio of the piezoelectric phase in the piezoelectric composite material, the density of the composite material can be reduced, and the purpose of reducing the acoustic impedance can be achieved, so that it can achieve optimal matching with water through the matching layer.

The high-power high-frequency directional emission underwater acoustic transducer shown in Figure 1 is prepared by the following steps:

1) Cutting a whole piece of piezoelectric ceramics into a periodically arranged piezoelectric ceramic column array;

2) place the processed rigid material frame between the piezoelectric ceramic column arrays, pour passive phase material (rubber with high thermal conductivity) in the gap between the frame and the piezoelectric ceramic column, and cure;

7) Adhere the processed trapezoidal matching layer on the electrode surface of the 1-1-3 piezoelectric composite material, and keep the bottom surface of each trapezoid facing the upper surface of the piezoelectric ceramic column;

8) Assemble the above-mentioned structures and structural parts, and weld wires and watertight cables;

9) Place the above structure in a mold, pour a waterproof sound-permeable layer, and complete the transducer fabrication after curing.

The key technology of the present invention includes:

1) Heat dissipation technology of piezoelectric composite materials and high-power underwater acoustic emission transducers.

Through the structure of the composite material inside the piezoelectric composite material and the high-power underwater acoustic emission transducer, a frame-type heat dissipation structure with excellent heat dissipation effect (that is, the third in the piezoelectric composite material) is drawn through the structure of the composite material. frame type heat dissipation structure formed by phase). On the one hand, clever use of the frame structure in the 1-1-3 type composite material not only ensures its original structural support, but also gives it the function of heat dissipation. On the other hand, this heat dissipation structure is closer to the source of heat generation, and wraps it in it to minimize the distance of heat transfer and increase the area of heat transfer, so as to achieve better heat dissipation effect.

2) High-power underwater acoustic emission transducer beam opening angle and sidelobe suppression technology.

For the 1-1-3 piezoelectric composites, the surface vibration distribution is not completely consistent, the vibration displacement of the piezoelectric phase is large, while the vibration displacement of the polymer phase is approximately zero. Therefore, according to the superposition principle of acoustic wave point source radiation, the beam opening angle of the transducer can be controlled by adjusting the arrangement between the piezoelectric elements inside the transducer, and the side lobe fluctuation can be adjusted to achieve the side lobe suppression effect and make the acoustic wave energy It is more concentrated in the main lobe and reduces the energy transfer loss.

In order to improve the power of the transmitting transducer and control the beam opening angle, it can be realized in the form of an array of transmitting transducers, as shown on the left side of Figure 4. Compared with a single transmitting transducer, the radiating surface of the transducer array is increased, the beam opening angle is smaller, and the corresponding hydrophone requires a smaller area and a longer working distance. Considering the actual working conditions of underwater wireless charging, the receiving hydrophone may appear in both the far field and the near field of the transmitting transducer. Therefore, in order to improve the charging range, the size of the hydrophone should not be suitable. too small, and can take the form of an array of receiving hydrophones. Once the hydrophone is in the near-field region of the transmitting transducer, the hydrophone can be decomposed into multiple sub-hydrophones, and the sub-hydrophones satisfying the far-field conditions of the sub-transmitting transducers realize the reception of sound energy. Therefore, in practical work, the hydrophone array also needs to design multiple independent charging circuits.

Using the underwater acoustic transducer of the present invention, the wireless long-distance power supply of the underwater unmanned vehicle and the underwater sensor network can be realized. The conversion of electrical energy to sound energy is realized through the inverse piezoelectric effect of the underwater acoustic transducer, and then the sound waves are radiated through the water medium. The sound energy is converted into electrical energy, and then the load is charged through the matching circuit.

The present invention prepares the above-mentioned directional underwater acoustic emission transducer by using a large-sized piezoelectric composite material, the piezoelectric composite material has a side length of 200 mm, and the performance index of the transducer is shown in FIG. 3 . The resonant frequency of the transducer is about 150kHz, the maximum transmission voltage response reaches 183.6dB, the -3dB operating frequency range: 126kHz to 174kHz, and the bandwidth reaches 48kHz. The maximum sound source level of the transducer is 233.2dB, and the -3dB directivity opening angle is 3°, that is, when the charging distance is 1m, the -3dB coverage arc length is 5cm; when the charging distance is 10m, the -3dB coverage circle The arc length is 50cm. The maximum side lobe level of the transducer is -23.65dB, indicating that the energy is mainly concentrated in the main lobe.

The specific embodiments of the present invention disclosed above and the accompanying drawings are intended to help understand the content of the present invention and implement it accordingly. Those of ordinary skill in the art can understand that various replacements can be made without departing from the spirit and scope of the present invention. , variations and modifications are possible. The present invention should not be limited to the contents disclosed in the embodiments of the present specification and the accompanying drawings, and the protection scope of the present invention is subject to the scope defined by the claims.

Claims

A high-power high-frequency directional emission underwater acoustic transducer is characterized in that it includes piezoelectric composite materials, electrodes, matching layers, heat dissipation structures, and sound-absorbing backings; the piezoelectric composite materials are of type 1-1-3 The piezoelectric composite material is composed of a piezoelectric phase, a passive phase and a structural phase. The piezoelectric phase is an array of piezoelectric material columns, the structural phase is a rigid material frame located between the piezoelectric material columns, and the passive phase is located between the piezoelectric phase and the piezoelectric material. A flexible polymer between structural phases; the piezoelectric composite material covers the electrodes on both surfaces in the thickness direction; the matching layer is located on one side of the piezoelectric composite material, the heat dissipation structure and the suction The acoustic backing is located on the other side of the piezoelectric composite material; the heat dissipation structure is a rigid material frame identical to the structure in the piezoelectric composite material; the sound absorption backing is distributed in the heat dissipation structure .
The high-power high-frequency directional emission underwater acoustic transducer according to claim 1, wherein the heat dissipation structure and the structure in the piezoelectric composite material are precisely matched to each other to achieve good heat transfer.
The high-power high-frequency directional emission underwater acoustic transducer according to claim 1, further comprising a casing and a cable; the casing is a metal casing, and the heat dissipation structure is closely connected with the metal casing to achieve good heat dissipation transfer; the cable connects the leads on the electrode.
The high-power high-frequency directional emission underwater acoustic transducer according to claim 1, wherein the piezoelectric phase is a low-loss piezoelectric ceramic or piezoelectric crystal.
The high-power high-frequency directional emission underwater acoustic transducer according to claim 1, wherein the passive phase is a high temperature resistant flexible polymer.
The high-power high-frequency directional emission underwater acoustic transducer according to claim 5, wherein the passive phase is polyphenylene, parylene, polyarylene ether, polyarylate, aromatic polyamide , one of polyimide and silicone rubber.
The high-power high-frequency directional emission underwater acoustic transducer according to claim 1, wherein the structural phase is a grid structure prepared by selecting materials with good heat dissipation performance by machining; The material of the phase is carbon fiber composite material or low density metal material.
The method according to claim 1, wherein the matching layer is a trapezoidal matching layer, and the lower bottom surface of each trapezoid of the trapezoidal matching layer is opposite to the upper surface of the piezoelectric material column in the piezoelectric composite material .
A method for preparing the high-power high-frequency directional emission underwater acoustic transducer according to claim 1, characterized in that, comprising the following steps:

1) Cutting a whole piece of piezoelectric material into a periodically arranged piezoelectric material column array;

2) The processed rigid material frame is placed between the piezoelectric material column arrays, and the passive phase material is poured into the gap between the rigid material frame and the piezoelectric material column, and cured;

3) Grinding the upper and lower surfaces to the required thickness, and preparing metal electrodes on the upper and lower surfaces to form a 1-1-3 piezoelectric composite material;

4) Weld the wires on the upper and lower electrode surfaces of the 1-1-3 piezoelectric composite material;

5) Adhere to each other the heat dissipation structure formed by the lower electrode surface of the 1-1-3 piezoelectric composite material and the rigid material frame, and keep the rigid material frame and the rigid material frame inside the 1-1-3 piezoelectric composite material to match each other ;

6) The sound-absorbing backing material is poured or bonded in the heat dissipation structure composed of the rigid material frame, and cured;

7) Adhere the processed trapezoidal matching layer on the electrode surface of the 1-1-3 type piezoelectric composite material, and keep the lower bottom surface of each trapezoid facing the upper surface of the piezoelectric material column;

8) Assemble the structure obtained in step 7) with the structural parts, and weld the wire and the watertight cable;

9) Place the structure obtained in step 8) in a mold, pour a waterproof sound-permeable layer, and complete the transducer fabrication after curing.
An array of transmitting underwater acoustic transducers, characterized in that it comprises at least two high-power and high-frequency directional transmitting underwater acoustic transducers according to any one of claims 1 to 8.