A tubular piezoelectric stack and a transducer using the tubular piezoelectric stack

Abstract

The present invention belongs to the field of hydroacoustics, specifically a tubular piezoelectric stack and a transducer using the tubular piezoelectric stack, including a tubular piezoelectric stack, a matching layer, a decoupling sheet, an anti-sound cover plate, a waterproof and sound-permeable layer, and an output cable. The tubular piezoelectric stack comprises a plurality of longitudinally polarized piezoelectric rings, an electrode sheet, an annular end cap, and a prestressed screw. The piezoelectric stack type circular tube transducer of the present invention utilizes a tubular piezoelectric stack as a sensitive element, and grooves are formed on the annular end cap to form a comb-like structure, which can effectively increase the vibration mode of the transducer and has a higher transmitting voltage response, receiving sensitivity, and working bandwidth than ordinary circular tube transducers. By changing the number of piezoelectric rings in the stack and the electrical series and parallel output modes, the output impedance of the transducer can be adjusted, making it easier to match with the back-end circuit in application.

Description

Technical Field

[0001] The invention belongs to the field of hydroacoustics, and in particular relates to a tubular piezoelectric stack and a transducer using the tubular piezoelectric stack. Background Art

[0002] The ocean has important economic and military value and contains rich natural resources. With the global shortage of resources, the development and utilization of the ocean has increasingly important economic value and strategic significance. So far, among the various technologies that people are familiar with and master, sound waves are the most effective form of propagation in the ocean. The sonar system uses the propagation characteristics of sound signals in the medium to obtain relevant parameter information of the medium, realize underwater detection, communication and positioning functions, and is an indispensable technical equipment for ocean development.

[0003] As a key device of the sonar system, the underwater acoustic transducer is a device for generating and receiving underwater sound wave signals. Its performance parameters determine the quality of the underwater sonar system. With the deepening of research in the marine field, the requirements for sonar equipment are constantly increasing. In order to further improve the performance of the sonar system such as the range, working efficiency, anti-multipath characteristics and response speed, the transducer is required to have a higher transmission voltage response, receiving sensitivity and working bandwidth.

[0004] Circular tube transducers are one of the most widely used structural types in the design of medium and high frequency transducers, and are widely used in various sonar systems. Traditional circular tube transducers usually use radially polarized piezoelectric ceramic circular tubes as sensitive elements. Although they have the advantages of simple structure and low cost, their transmitting voltage response and receiving sensitivity are low, and their working bandwidth is narrow. Therefore, further improving the transmitting voltage response, receiving sensitivity and working bandwidth of circular tube transducers has become an urgent problem to be solved. Summary of the invention

[0005] The purpose of the present invention is to provide a tubular piezoelectric stack and a transducer using the tubular piezoelectric stack, which uses a longitudinally polarized tubular piezoelectric stack as a sensitive element of the transducer and can be used as an underwater transmitting sound source and a receiving hydrophone. Combined with the annular end cover design of a comb-like structure, it has the advantages of high response, high sensitivity, broadband and adjustable impedance.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A tubular piezoelectric stack, comprising an annular end cap, a longitudinally polarized piezoelectric ring and an electrode sheet; a plurality of piezoelectric rings are stacked and bonded to form a piezoelectric ring stack, the annular end caps are symmetrically arranged at both ends of the piezoelectric ring stack, and the electrode sheets are arranged between the annular end caps and the piezoelectric rings and between adjacent piezoelectric rings;

[0008] On the opposite side of the annular end cover where the piezoelectric ring is connected, a plurality of decoupling grooves are provided along the circumferential direction of the annular end cover, and the decoupling grooves are in a comb-teeth shape on the circumference of the annular end cover.

[0009] Furthermore, a plurality of prestressed screw rods are arranged between the annular end covers at both ends, and the annular end covers and the prestressed screw rods apply axial preload force.

[0010] Preferably, the number of the piezoelectric rings is an even number, and the piezoelectric rings are electrically connected in series or in parallel.

[0011] Preferably, the piezoelectric ring is made of piezoelectric ceramics or piezoelectric single crystals. Those skilled in the art can select other piezoelectric materials as needed.

[0012] The present invention also provides a transducer, which comprises a matching layer, a decoupling sheet, an anti-sound cover plate, a waterproof sound-permeable layer, an output cable and the above-mentioned tubular piezoelectric stack;

[0013] Anti-sound cover plates are arranged at both ends of the tubular piezoelectric stack, and the tubular piezoelectric stack is packaged by a matching layer; the matching layer is wrapped with a waterproof and sound-permeable layer, and an output cable is arranged on the top of the tubular piezoelectric stack through the matching layer and the waterproof and sound-permeable layer, and the output cable is connected to the electrode sheet through a wire; a decoupling sheet is arranged in the decoupling groove.

[0014] Preferably, the decoupling sheet is made of cork rubber.

[0015] Preferably, the matching layer is made of epoxy resin potting material.

[0016] Preferably, the sound-reflecting cover plate is made of hard foam material.

[0017] Preferably, the waterproof and sound-permeable layer is made of plastic, polyurethane or rubber.

[0018] Preferably, the packaging shape of the transducer includes but is not limited to a cylindrical shape.

[0019] Specifically, the piezoelectric stacked circular tube transducer of the present invention comprises a tubular piezoelectric stack, a matching layer, a decoupling sheet, an anti-sound cover plate, a waterproof sound-permeable layer and an output cable. The tubular piezoelectric stack is formed by bonding a plurality of piezoelectric rings and electrode sheets, and two annular end caps along the axial direction, the two annular end caps are connected by a prestressed screw, an electrode sheet is used to lead out the electrode between the piezoelectric rings, and the overall structure is bonded by epoxy resin material.

[0020] The piezoelectric ring adopts longitudinal polarization, and the polarization direction is along the axial direction. When used, it can be installed in the forward direction or the reverse direction.

[0021] The tubular piezoelectric stack is divided into two types: series operation and parallel operation. When assembling a piezoelectric stack working in parallel, the piezoelectric rings are alternately installed and stacked according to the positive and negative polarization directions, and the positive and negative electrodes are cross-leaded after bonding. When assembling a piezoelectric stack working in series, the polarization directions of all piezoelectric rings are in the same direction, and the electrodes are led out from the two electrode sheets at the end.

[0022] The annular end cover is grooved along the circumferential direction to form a comb-like structure.

[0023] The groove of the annular end cover is filled with a decoupling sheet, and the decoupling sheet is made of cork rubber or other low sound velocity decoupling materials.

[0024] The prestressed screws are evenly installed along the circumferential direction and are used to connect the two annular end covers of the piezoelectric stack. Their main function is to provide axial preload for the piezoelectric element. They can be made of metal or non-metal, and the specific number is not limited.

[0025] The electrode sheet is a copper sheet or other conductive metal having the same radial dimension as the piezoelectric ring.

[0026] The piezoelectric stack is externally infused with a matching layer to form the main vibration structure of the transducer.

[0027] The matching layer material is epoxy resin material.

[0028] The piezoelectric stacked circular tube transducer mainly radiates sound waves radially when used underwater, and the end is isolated by an anti-sound cover plate and the outside is encapsulated by rubber.

[0029] The anti-sound cover plate is a low-impedance hard foam material, or other materials with anti-sound properties.

[0030] The waterproof and sound-permeable layer is packaged with waterproof materials such as plastic, polyurethane, rubber, epoxy resin, etc.

[0031] The piezoelectric stacked circular tube transducer of the present invention utilizes a tubular piezoelectric stack as a sensitive element, and grooves are cut on the annular end cover to form a comb-like structure, which can effectively increase the vibration mode of the transducer and has a higher transmitting voltage response, receiving sensitivity and working bandwidth than ordinary circular tube transducers. By changing the number of piezoelectric rings in the stack and the electrical series and parallel output modes, the output impedance of the transducer can be adjusted, making it easier to match with the back-end circuit in application. The device of the present invention is used for underwater sound wave reception and transmission, and is mainly used in the fields of underwater acoustic detection, communication, positioning, etc. to improve the working distance and working efficiency of the sonar system.

[0032] Compared with the prior art, the advantages of the present invention are:

[0033] A tubular piezoelectric stack is formed by bonding multiple longitudinally polarized piezoelectric rings, electrode sheets and two annular end caps axially, thus realizing a new type of circular tube transducer structure. The performance advantage of the longitudinally polarized piezoelectric material with high piezoelectric constant is used to improve the transmitting voltage response and receiving sensitivity of the transducer. The longitudinal vibration mode, radial vibration mode and bending vibration mode of the tubular piezoelectric stack are coupled to achieve broadband operation, thus overcoming the shortcomings of the traditional circular tube transducer in terms of transmitting voltage response, receiving sensitivity and working bandwidth. In addition, by adjusting the number of piezoelectric rings and the electrical output mode, the output impedance of the transducer can be flexibly adjusted, making it easier to match with the back-end circuit when applied. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a cross-sectional view of a transducer of the present invention;

[0035] Figure 2 A side view of a tubular piezoelectric stack of the present invention;

[0036] Figure 3 is a cross-sectional view of the main vibration structure of the transducer of the present invention;

[0037] Figure 4 It is a schematic diagram of the transducer without prestressing structure of the present invention;

[0038] Figure 5 It is a schematic diagram of piezoelectric element assembly and electrical connection when the transducer of the present invention works in parallel;

[0039] Figure 6 It is a schematic diagram of piezoelectric element assembly and electrical connection when the transducers of the present invention work in series;

[0040] Figure 7 It is a schematic diagram of the broadband working principle of the transducer of the present invention;

[0041] Figure 8 is a test curve of the voltage response of the transducer of the present invention;

[0042] Fig. 9 is a test curve of the transducer receiving voltage sensitivity of the present invention;

[0043] Reference numerals:

[0044] Annular end cover 1, piezoelectric ring 2, electrode sheet 3, matching layer 4, decoupling sheet 5, prestressed screw 6, anti-sound cover plate 7, waterproof and sound-permeable layer 8, output cable 9. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] Example 1

[0047] like Figure 1 As shown, a transducer comprises a matching layer 4, a decoupling sheet 5, an anti-sound cover plate 7, a waterproof sound-permeable layer 8 and an output cable 9, and a tubular piezoelectric stack;

[0048] like Figure 2-3 As shown, the tubular piezoelectric stack comprises an annular end cap 1, a longitudinally polarized piezoelectric ring 2 and an electrode sheet 3; a plurality of piezoelectric rings 2 are stacked and bonded to form a piezoelectric ring stack, the annular end caps 1 are symmetrically arranged at both ends of the piezoelectric ring stack, and the electrode sheets 3 are arranged between the annular end caps 1 and the piezoelectric rings 2 and between adjacent piezoelectric rings;

[0049] On the side opposite to the side where the annular end cover 1 and the piezoelectric ring 2 are connected, a plurality of decoupling grooves are provided along the circumferential direction of the annular end cover 1, and the decoupling grooves are in a comb-tooth shape on the circumference of the annular end cover;

[0050] Anti-sound cover plates 7 are arranged at both ends of the tubular piezoelectric stack, and the tubular piezoelectric stack is packaged by a matching layer 4; the matching layer 4 is wrapped with a waterproof and sound-permeable layer 8, and an output cable 9 is arranged on the top of the tubular piezoelectric stack through the matching layer 4 and the waterproof and sound-permeable layer 8, and the output cable 9 is connected to the electrode sheet through a wire; the decoupling sheet 5 is arranged in the decoupling sheet groove.

[0051] A plurality of prestressed screws 6 are arranged between the annular end covers 1 at both ends, and the annular end covers and the prestressed screws apply axial preload.

[0052] The number of the piezoelectric rings 2 is an even number, and the piezoelectric rings are connected in electrical parallel.

[0053] The piezoelectric ring 2 is made of piezoelectric ceramics or piezoelectric single crystal.

[0054] The decoupling sheet is made of cork rubber.

[0055] The matching layer is made of epoxy resin potting material.

[0056] The sound-reflecting cover plate is made of hard foam material.

[0057] The waterproof and sound-permeable layer is made of plastic, polyurethane or rubber.

[0058] The packaging shape of the transducer is cylindrical.

[0059] The main steps of making the transducer of the present invention are as follows:

[0060] 1) Soak a sufficient number of annular end caps 1, piezoelectric rings 2, and electrode sheets 3 in alcohol for more than two hours, take them out, wipe them clean with absorbent cotton, and place them in a drying oven at 80 degrees for two hours for use.

[0061] 2) Evenly apply epoxy resin adhesive on the end of the annular end cap 1 without the cutting groove, the upper and lower end surfaces of the piezoelectric ring 2, and the outer surface of the electrode sheet 3. Prepare the positioning mold, and axially align the piezoelectric ring 2, the electrode sheet, and the annular end cap. Figure 5 The piezoelectric rings 2 should be installed alternately in the positive and negative polarization directions, ensuring that the polarization directions of adjacent piezoelectric rings 2 are opposite, and the end of the annular end cap 1 without the cutting groove is bonded to the stack, and the side with the cutting groove faces outward, ensuring that there are metal electrode sheets 3 between the piezoelectric rings 2 and between the piezoelectric rings 2 and the annular end cap 1.

[0062] 3) After installation, use six prestressed screws 6 to connect the annular end caps 1 at both ends, tighten the prestressed screws with a torque wrench, apply axial preload, and cure in a drying oven at 80°C for more than 6 hours. Figure 2 The tubular piezoelectric stack shown.

[0063] 4) Remove the cured tubular piezoelectric stack from the mold, prepare a sufficient number of decoupling sheets 5, apply silicone rubber on the decoupling sheets 5 and fill them into the slits (decoupling grooves) of the annular end cover 1. After filling, place them at room temperature until the silicone rubber is cured. Figure 4 The parallel output mode shown is to weld the wires on the electrode sheet 3. The piezoelectric stack after welding the wires is installed in the mold, and the matching layer 4 of the epoxy resin is poured. It is cured in a drying oven at 80 degrees for 6 hours and naturally cooled to room temperature. Figure 3 The tubular structure shown is to be waterproofed and packaged in the next step.

[0064] 5) Since there is an anti-phase zone between the radial direction and the end of the piezoelectric stack, an anti-sound cover plate 7 is required to shield the radiation at the end. The anti-sound cover plate 7 is bonded to the end of the piezoelectric stack with silicone rubber, the wire is connected to the output cable 9, and then the polyurethane rubber waterproof and sound-permeable layer 8 is encapsulated on the outer surface of the transducer as a whole, and cured in an 80°C drying oven for more than 8 hours, and after the polyurethane rubber is completely cured, it is cooled to room temperature and taken out.

[0065] When the transducer is working, the tubular piezoelectric stack works in the vibration mode, which can significantly improve the transmitting voltage response and receiving sensitivity of the transducer, such as Figure 8 and Fig. 9 As shown. Figure 7 As shown, the transducer has three vibration frequencies, namely, height vibration f1, radial vibration f2, and bending vibration f3 of the comb-shaped structure. Broadband operation can be achieved by coupling the three vibration modes.

[0066] Example 2

[0067] Different from the first embodiment, the present embodiment is a transducer with a series structure, and the polarization directions of all piezoelectric rings should face the same direction. Figure 6, the specific implementation is similar to the parallel structure.

[0068] Example 3

[0069] Different from the first embodiment, the present embodiment does not use the prestressed screw rod 6. Figure 4 As shown, the transducer is used as a low-power transmitter or receiver.

[0070] The process parameters (such as temperature, time, etc.) of the present invention can realize the method by taking upper and lower limits and interval values, and the embodiments are not listed one by one here.

[0071] Any contents not described in detail in the present invention can be based on the conventional technical knowledge in the art.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A tubular piezoelectric stack, characterized in that: The tubular piezoelectric stack comprises an annular end cap (1), a longitudinally polarized piezoelectric ring (2) and an electrode sheet (3); a plurality of piezoelectric rings (2) are stacked and bonded to form a piezoelectric ring stack, the annular end caps (1) are symmetrically arranged at both ends of the piezoelectric ring stack, and the electrode sheets (3) are arranged between the annular end caps (1) and the piezoelectric rings (2) and between adjacent piezoelectric rings; On the side opposite to the side where the annular end cover (1) and the piezoelectric ring (2) are connected, a plurality of decoupling grooves are provided along the circumferential direction of the annular end cover (1), and the decoupling grooves are in a comb-tooth shape on the circumference of the annular end cover.

2. The tubular piezoelectric stack according to claim 1, characterized in that: A plurality of prestressed screw rods (6) are arranged between the annular end covers (1) at both ends, and the annular end covers and the prestressed screw rods apply axial preload force.

3. The tubular piezoelectric stack according to claim 1, characterized in that: The piezoelectric rings (2) are connected electrically in series or in parallel.

4. The tubular piezoelectric stack according to claim 1, characterized in that: The piezoelectric ring (2) is made of piezoelectric ceramics or piezoelectric single crystals.

5. A transducer, comprising a matching layer (4), a decoupling sheet (5), an anti-sound cover plate (7), a waterproof sound-permeable layer (8) and an output cable (9), characterized in that: The transducer further comprises a tubular piezoelectric stack as claimed in any one of claims 1 to 4; Anti-sound cover plates (7) are arranged at both ends of the tubular piezoelectric stack, and the tubular piezoelectric stack is encapsulated by a matching layer (4); the matching layer (4) is wrapped with a waterproof sound-permeable layer (8), an output cable (9) is arranged on the top of the tubular piezoelectric stack through the matching layer (4) and the waterproof sound-permeable layer (8), and the output cable (9) is connected to the electrode sheet through a wire; and a decoupling sheet (5) is arranged in a decoupling groove.

6. The transducer according to claim 5, characterized in that The decoupling sheet is made of cork rubber.

7. The transducer according to claim 5, characterized in that The matching layer is made of epoxy resin potting material.

8. The transducer according to claim 5, characterized in that The sound-reflecting cover plate is made of hard foam material.

9. The transducer according to claim 5, characterized in that: The waterproof and sound-permeable layer is made of plastic.

10. The transducer according to claim 5, characterized in that The waterproof and sound-permeable layer is made of polyurethane.

11. The transducer according to claim 5, characterized in that The waterproof and sound-permeable layer is made of rubber.

12. The transducer according to claim 5, characterized in that The packaging shape of the transducer includes a cylindrical shape.

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