Cymbal type transducer with improved vibration limit

Abstract

The invention relates to a cymbal type transducer with improved vibration limit, which comprises a radiation panel, bent shells, middle bonding flat plates and a piezoelectric element, the symmetrical bent shells are arranged at the upper part and the lower part of the piezoelectric element, the middle bonding flat plates are arranged at the four contact parts of the piezoelectric element and the bent shells, the convex parts of the bent shells are connected with the radiation panel, and the middle bonding flat plates are connected with the radiation panel. The bending shell, the middle bonding flat plate and the piezoelectric element are bonded and fixed, and the bending shell is in a state of extruding towards the piezoelectric element when being fixed. The piezoelectric transducer has the beneficial effects that the piezoelectric element is made of a novel relaxor ferroelectric single crystal material, so that the piezoelectric coefficient is higher, and the transducer can realize higher transmitting power; the bonding area is increased, and the stress is smaller under the action of the same force, so that the bonding layer and the piezoelectric element can bear larger vibration force and hydrostatic pressure; prestress is directly increased in the fixing process of the bent shell, so that higher radiation power is achieved, the working water depth is larger, and lower resonant frequency is achieved.

Description

Technical Field

[0001] The present invention relates to a transducer structure, in particular to a cymbal-type transducer with improved vibration limit. Background Art

[0002] Compared with manned platforms, unmanned platforms have lower costs and higher flexibility, but they have smaller space and limited energy. At the same time, they must have the ability to sense underwater sound. Based on the above characteristics of unmanned platforms, the requirements for underwater acoustic transducer technology are small size and high efficiency.

[0003] The standard cymbal transducer is a miniaturized V-shaped flextensional transducer. Its advantages are that it can work at low frequencies due to its small size and simple structure. Its disadvantages are that it is not resistant to water pressure and has no prestress. Therefore, it is often used as a medium-power transmitting transducer. Existing research has made many improvements to the cymbal structure and materials.

[0004] The piezoelectric element material used is usually PZT piezoelectric ceramics, which are mostly in the shape of discs and rings. The 31 mode is used, but the piezoelectric coefficient d of the PZT piezoelectric element in the 31 direction is 31 Lower, PZT-4, PZT-8 and PZT-5 d 31 The piezoelectric coefficients of the relaxor ferroelectric single crystals are -123pC / N, -93pC / N and -274pC / N respectively. Some studies have used relaxor ferroelectric single crystal materials, mainly in the form of round and square pieces. The circular relaxor ferroelectric single crystal elements are polarized along the

[001] c direction, and the 31 mode is also used. 31 It is several times that of piezoelectric ceramics, with a maximum value of nearly 1000pC / N. The square relaxor ferroelectric single crystal element is polarized along the

[011] c direction, using the 32 mode, and the piezoelectric coefficient d 32 The commonly used ones are above 1500pC / N. Compared with emissive piezoelectric ceramic materials, relaxor ferroelectric single crystal materials have higher piezoelectricity and dielectricity, so they have higher power capacity and can achieve higher acoustic radiation intensity with smaller volume and weight. The disadvantage is that the stress limit is lower.

[0005] The compressive limit of piezoelectric ceramic elements is several times the tensile limit. When used in underwater acoustic emission transducers, it is usually necessary to pre-apply a certain amount of pressure, i.e. prestress, in the vibration direction of the piezoelectric element to increase the vibration displacement limit of the piezoelectric element. The shells at both ends of the cymbal transducer are not connected, and the overall stiffness is reduced, which is one of the reasons for the low resonant frequency. It also makes it difficult to effectively apply prestress, limiting the power output.

[0006] There are few studies on the application of prestress to cymbal transducers. Existing studies have shown that the resonant frequency can be increased or the structural size can be increased or the active material can be reduced. The method of applying prestress using the principle of thermal expansion and contraction is difficult to implement because the thermal expansion coefficient of the material is small. For small structures of millimeter or centimeter level, the deformation caused by thermal expansion is almost impossible to measure and may even be lower than the dimensional tolerance of the structural parts. Adding a connection structure to the shell in the thickness direction of the outer side of the element and applying prestress through external force will increase the structural size, reduce the small advantage, and increase the shell stiffness to reduce the low-frequency advantage of the bending mode. Summary of the invention

[0007] The present invention aims to solve the above-mentioned shortcomings of the prior art and provide a cymbal-type transducer with a compact structure, better performance and improved vibration limit.

[0008] The present invention solves its technical problems by adopting a technical solution: the cymbal-type transducer with improved vibration limit comprises a radiation panel, a curved shell, an intermediate bonding plate and a piezoelectric element, the upper and lower parts of the piezoelectric element are provided with symmetrical curved shells, the four contact points between the piezoelectric element and the curved shell are provided with intermediate bonding plates, the protrusion of the curved shell is connected to the radiation panel, the curved shell, the intermediate bonding plate and the piezoelectric element are bonded and fixed, and the curved shell is in a state of being squeezed toward the piezoelectric element when fixed.

[0009] The horizontal surface area of ​​the intermediate bonding plate is larger than the contact area between the curved shell and the piezoelectric element.

[0010] The outer edge of the middle bonding plate is flush with the outer edge of the piezoelectric element.

[0011] The outer edge in the horizontal direction of the contact point between the curved shell and the middle bonding plate is inside the outer edge in the horizontal direction of the middle bonding plate.

[0012] The piezoelectric element, the middle bonding plate and the radiation panel are rectangular parallelepiped structures, and the curved shell is a convex structure.

[0013] The size of the horizontal plane of the radiation panel is greater than the size of the horizontal plane of the piezoelectric element.

[0014] The middle bonding plate, the curved shell and the radiation panel are made of the same material.

[0015] The piezoelectric element is a rectangular parallelepiped with a length, width and thickness of 20 mm*10 mm*2 mm respectively. It is made of a new relaxor ferroelectric single crystal material PIN-46% PMN-30% PT. The single crystal element is polarized along the

[011] c direction. The two planes of the length and width of the piezoelectric element are used as the positive electrode and negative electrode planes respectively. The d 32 The direction is the same as the length direction of the piezoelectric element. 31The direction is the same as the width direction of the piezoelectric element. 33 The direction is the same as the thickness direction of the piezoelectric element; the d 32 -1693pC / N,d 31 675pC / N,d 33 It is 1068pC / N.

[0016] The material of the curved shell is titanium alloy, and the length, width and thickness are 19mm*10mm*0.3mm respectively. The raised platform on the top surface of the curved shell is 4mm away from the piezoelectric element, and the outer edge of the curved shell in the horizontal direction is 0.5mm away from the outer edge of the middle bonding plate in the horizontal direction.

[0017] The middle bonding plate and the radiation panel are both rectangular parallelepipeds, and are made of titanium alloy. The length, width and thickness of the middle bonding plate are 10mm*4mm*0.3mm respectively, and the length, width and thickness of the radiation panel are 30mm*20mm*2mm respectively.

[0018] The beneficial effects of the present invention are as follows: the piezoelectric element of the present invention adopts a new relaxor ferroelectric single crystal material, and compared with the PZT piezoelectric ceramic element, the piezoelectric coefficient is higher, and the transducer can achieve a higher transmission power; the bonding area is increased, and under the action of the same force, the stress is smaller, so that the bonding layer and the piezoelectric element can withstand greater vibration force and hydrostatic pressure; the prestress is directly added in the fixation of the curved shell, which has a higher radiation power, a larger working water depth, and a lower resonance frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the main structure of the present invention;

[0020] Figure 2 It is a side view structural schematic diagram of the present invention;

[0021] Figure 3 It is a schematic diagram of the top structure of the present invention.

[0022] Description of reference numerals: radiation panel 1 , curved shell 2 , middle bonding plate 3 , piezoelectric element 4 . DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings:

[0024] As shown in the figure, the cymbal-shaped transducer with improved vibration limit includes a radiation panel 1, a curved shell 2, an intermediate bonding plate 3 and a piezoelectric element 4. The piezoelectric element 4, the intermediate bonding plate 3 and the radiation panel 1 are rectangular parallelepiped structures, and the curved shell 2 is a convex structure. The upper and lower parts of the piezoelectric element 4 are provided with symmetrical curved shells 2, and the four contact points between the piezoelectric element 4 and the curved shell 2 are all provided with intermediate bonding plates 3, and the horizontal surface area of ​​the intermediate bonding plate 3 is larger than the contact area between the curved shell 2 and the piezoelectric element 4. The convex part of the curved shell 2 is connected to the radiation panel 1, and the radiation surfaces on both sides of the transducer are in contact with water, and the sides of the transducer are separated from water by a watertight structure.

[0025] The curved shell 2, the intermediate bonding plate 3 and the piezoelectric element 4 are bonded and fixed. When the curved shell 2 is fixed, it is in a state of squeezing the piezoelectric element 4, that is, a constant force is applied to the curved shell 2 in the longitudinal direction of the curved shell 2, so that the curved shell 2 is pre-stretched and deformed in the transverse direction, and this state is maintained to solidify the adhesive. After the structure is solidified and stabilized, the curved shell 2 has a longitudinal inward contraction force, and a pre-pressure is applied to the piezoelectric element 4 in the transverse direction through the intermediate bonding plate 3. When the transducer is placed in water, the hydrostatic pressure acts on the radiation surface, so that the curved shell 2 is stretched in the transverse direction. As the water depth increases, the contraction force of the curved shell 2 gradually decreases to zero. When the water depth increases further, the curved shell 2 becomes stretched. At this time, the stress state of the transducer structure is the same as the stress state of the traditional structure without prestress. Therefore, the application of prestress can increase the working water depth of the transducer. The curved shell 2 and the piezoelectric element 4 are bonded through the intermediate bonding plate 3 with a larger area, which increases the contact area. Under the same force, the stress is reduced, and the working depth is further increased.

[0026] Similarly, when the piezoelectric element 4 performs elongation vibration under the excitation of an electrical signal, as the electrical signal increases, the element first offsets the prestress applied by the curved shell 2, and then tensile stress appears. The application and increase of prestress contributes to a greater output of vibration displacement of the piezoelectric element 4.

[0027] The addition of a larger area of ​​the middle bonding plate 3 structure increases the resonant frequency of the transducer, and the pre-deformation of the curved shell 2 reduces the resonant frequency of the transducer. The effects of the two structures on the resonant frequency of the transducer are almost offset, and ultimately have little impact on the resonant frequency of the transducer.

[0028] The outer edge of the intermediate bonding plate 3 is flush with the outer edge of the piezoelectric element 4. The outer edge of the curved shell 2 in the horizontal direction at the contact point with the intermediate bonding plate 3 is inside the outer edge of the intermediate bonding plate 3 in the horizontal direction. The size of the horizontal plane of the radiation panel 1 is larger than the size of the horizontal plane of the piezoelectric element 4. The intermediate bonding plate 3, the curved shell 2 and the radiation panel 1 are made of the same material.

[0029] The transducer has a length, width and height of 30mm*20mm*13.2mm. The piezoelectric element 4 is a rectangular parallelepiped with a length, width and thickness of 20mm*10mm*2mm respectively. It is made of a new relaxor ferroelectric single crystal material PIN-46%PMN-30%PT. The single crystal element is polarized along the

[011] c direction. The two planes of the length and width of the piezoelectric element 4 are used as the positive and negative electrode planes respectively. The d 32 The direction is the same as the length direction of the piezoelectric element 4. 31 The direction is the same as the width direction of the piezoelectric element 4. 33 The direction is the same as the thickness direction of the piezoelectric element 4; the d 32 -1693pC / N,d 31 675pC / N,d 33 It is 1068pC / N.

[0030] The material of the curved shell 2 is titanium alloy, and the length, width and thickness are 19mm*10mm*0.3mm respectively. The two curved shells 2 are symmetrically distributed. The contact length between the curved shell 2 and the middle bonding plate 3 is 1.5mm. The raised platform on the top surface of the curved shell 2 is 4mm away from the piezoelectric element 4, and the outer edge of the curved shell 2 in the horizontal direction is 0.5mm away from the outer edge of the middle bonding plate 3 in the horizontal direction.

[0031] The middle bonding plate 3 and the radiation panel 1 are both cuboids, made of titanium alloy. The length, width and thickness of the middle bonding plate 3 are 10mm*4mm*0.3mm respectively, and the length, width and thickness of the radiation panel 1 are 30mm*20mm*2mm respectively. The two radiation panels 1 are connected at the platform of the protrusion of the curved shell 2 and are symmetrically distributed. The inner plane of the radiation panel 1 contacts the top platform of the protrusion of the curved shell 2, and the center of the inner plane of the radiation panel 1 coincides with the center of the top platform of the curved shell 2.

[0032] The piezoelectric element 4 adopts a rectangular relaxor ferroelectric single crystal element polarized along the

[011] c direction, and utilizes its high piezoelectricity in the 32 direction to improve the vibration displacement output capacity of the active element; the curved shell 2 adopts a cymbal-type transducer bending structure with a large output displacement, and increases the bonding area between the shell and the piezoelectric element 4, thereby increasing the disengagement force between the shell, adhesive, and element; at the same time, after the shell is longitudinally pre-compressed, it is bonded and assembled with the piezoelectric element, and after curing, the piezoelectric element is pre-stressed by the shell.

[0033] The structure of the present invention is compared with the existing research on prestressing of cymbal-type transducers. The difference is that the existing cymbal-type transducers apply prestress through thermal expansion and contraction or external force, while the present solution directly pre-compresses the shell and applies prestress using the shell's own resilience.

[0034] The present invention uses a thin intermediate adhesive plate to increase the bonding area without changing or increasing the horizontal dimensions of the curved shell and the piezoelectric element, and only relies on the deformation of the curved shell; at the same time, the increase in resonant frequency caused by the addition of the intermediate adhesive plate and the decrease in resonant frequency caused by the longitudinal compression of the curved shell offset each other, so that the resonant frequency does not change.

[0035] Compared with the IV-type flextensional transducer and other transducers that apply prestress by contracting their own shells, the shells at both ends of the cymbal-type transducer of the present invention are not connected; the surface of force applied is parallel to the vibration direction of the piezoelectric element, and the prestress is applied by the curing and stabilizing adhesive of the bending shell rebound force, and the applied prestress is frictional force, while the surface of force applied by the IV-type flextensional transducer and other transducers is perpendicular to the vibration direction of the piezoelectric element, and the prestress is directly applied to the piezoelectric stack through the shell, and the applied prestress is compressive stress. The present invention applies higher prestress by increasing the adhesive area and pre-deformation method, thereby improving the hydrostatic pressure resistance.

[0036] The cymbal-shaped transducer with improved vibration limit provided by the present invention adopts a structural design of applying and improving prestress. Compared with the non-prestressed structure and the existing prestressed structure design, it has higher radiation power, greater working water depth and lower resonance frequency. It can be applied to high-power acoustic emission in scenarios with limited volume, weight and energy.

[0037] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A cymbal-shaped transducer with an improved vibration limit, comprising a radiation panel (1), a curved housing (2), an intermediate bonding plate (3) and a piezoelectric element (4), wherein: Symmetrical curved shells (2) are provided at the upper and lower parts of the element (4); intermediate bonding plates (3) are provided at four contact points between the piezoelectric element (4) and the curved shell (2); the protrusion of the curved shell (2) is connected to the radiation panel (1); the curved shell (2), the intermediate bonding plate (3) and the piezoelectric element (4) are bonded and fixed; when the curved shell (2) is fixed, it is in a state of being pressed toward the piezoelectric element (4).

2. The cymbal-type transducer with improved vibration limit according to claim 1, characterized in that: The horizontal surface area of ​​the intermediate bonding flat plate (3) is larger than the contact area between the curved shell (2) and the piezoelectric element (4).

3. The cymbal-type transducer with improved vibration limit according to claim 1 or 2, characterized in that: The outer edge of the middle bonding plate (3) is flush with the outer edge of the piezoelectric element (4).

4. The cymbal-type transducer with improved vibration limit according to claim 3, characterized in that: The outer edge in the horizontal direction of the contact point between the curved shell (2) and the middle bonding plate (3) is inside the outer edge in the horizontal direction of the middle bonding plate (3).

5. The cymbal-type transducer with improved vibration limit according to claim 4, characterized in that: The piezoelectric element (4), the intermediate bonding plate (3) and the radiation panel (1) are rectangular parallelepiped structures, and the curved shell (2) is a convex structure.

6. The cymbal-type transducer with improved vibration limit according to claim 5, characterized in that: The size of the horizontal plane of the radiation panel (1) is greater than the size of the horizontal plane of the piezoelectric element (4).

7. The cymbal-type transducer with improved vibration limit according to claim 5, characterized in that: The intermediate bonding plate (3), the curved shell (2) and the radiation panel (1) are made of the same material.

8. The cymbal-type transducer with improved vibration limit according to claim 1, characterized in that: The piezoelectric element (4) is a rectangular parallelepiped and is made of relaxor ferroelectric single crystal material PIN-46% PMN-30% PT. The single crystal element is polarized along the [011]c direction. The two planes of the length and width of the piezoelectric element (4) are used as the positive electrode and negative electrode planes respectively. The d 32 The direction is the same as the length direction of the piezoelectric element (4), and the d 31 The direction is the same as the width direction of the piezoelectric element (4). 33 The direction is the same as the thickness direction of the piezoelectric element (4); the d 32 -1693pC / N,d 31 675pC / N,d 33 It is 1068pC / N.

9. The cymbal-type transducer with improved vibration limit according to claim 1, characterized in that: The material of the curved shell (2) is titanium alloy, and the length, width and thickness are 19 mm*10 mm*0.3 mm respectively. The raised platform on the top surface of the curved shell (2) is 4 mm away from the piezoelectric element (4), and the outer edge of the curved shell (2) in the horizontal direction is 0.5 mm away from the outer edge of the middle bonding plate (3) in the horizontal direction.

10. The cymbal-type transducer with improved vibration limit according to claim 1, characterized in that: The intermediate bonding plate (3) and the radiation panel (1) are both rectangular parallelepipeds, and are made of titanium alloy.

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