Bent disc transducer utilizing deformation in ceramic thickness direction

Abstract

The invention relates to a bending disc transducer utilizing deformation in the ceramic thickness direction. The bending disc transducer comprises a disc-shaped inner supporting plate. The piezoelectric ceramic stacks are uniformly arranged at intervals in the circumferential direction of the internal supporting plate and are fixed on the outer side of the internal supporting plate; wherein the polarization direction of the piezoelectric ceramic stack is consistent with the thickness direction of the piezoelectric ceramic stack. A driving mode is creatively changed, and the disc is driven to generate bending vibration by telescopic vibration of the piezoelectric ceramic stack in the thickness direction, so that the ceramic stack mainly bears compressive stress instead of tensile stress under the action of hydrostatic pressure, and the characteristic of high compressive strength of a ceramic material is fully utilized; and the hydrostatic pressure resistance of the bending disc transducer is improved in a breakthrough manner.

Description

Technical Field

[0001] This invention belongs to the field of underwater acoustic transducer technology, specifically relating to a curved disk transducer that utilizes the deformation of ceramic thickness direction. Background Technology

[0002] Underwater acoustic transducers are key components for converting acoustic energy into electrical energy and are widely used in underwater communication, target detection, marine resource exploration, and environmental monitoring. Curved disk transducers, as a classic low-frequency transducer, are valued for their relatively simple structure, small size, light weight, and ability to achieve a large radiating area at lower frequencies.

[0003] Traditional curved disc transducers use the radial deformation of a ceramic disc for sound radiation, similar to the vibration of a diaphragm. Under hydrostatic pressure, this diaphragm-like shape causes the ceramic to bend axially. For ceramics that are resistant to pressure but not to tension, this deformation easily leads to breakage at the bonding surface, making it difficult to achieve deep-water operation at large sizes. For example, a curved disc with a diameter of 400mm can only operate at a depth of less than 100 meters.

[0004] To improve the pressure resistance of curved disk transducers, existing technologies mainly employ two approaches: one is an overflow design that allows water to enter the transducer to balance the hydrostatic pressure, but this introduces additional acoustic load and mass, significantly reducing radiation efficiency and affecting frequency characteristics; the other is an internal oil-filled pressure compensation design, which is structurally complex, requires high reliability, and may also adversely affect acoustic performance. Other improved designs include a patent application (CN107580274A) for a pieced curved disk underwater acoustic transducer, which uses pieced ceramic strips to increase the driving volume. However, this improvement may not fundamentally change the stress state of the ceramic (still under tension or bending), limiting its effectiveness in significantly improving the deep-water working capability of large-size curved disks. While a patent application (CN109195066A) for an ultra-low frequency curved disk transducer solves the driving problem for large disks, the pressure resistance bottleneck remains.

[0005] Therefore, there is an urgent need for a new type of curved disc transducer structure that can fundamentally improve the stress state of piezoelectric ceramic elements in deep water environments and significantly enhance their hydrostatic pressure resistance while maintaining the advantages of traditional curved discs in terms of low frequency and small size. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a curved disk transducer that utilizes the deformation of ceramic in the thickness direction. This transducer innovatively changes the driving method and uses the expansion and contraction vibration of the piezoelectric ceramic stack in the thickness direction to drive the disk to generate bending vibration. As a result, under hydrostatic pressure, the ceramic stack mainly bears compressive stress rather than tensile stress, making full use of the high compressive strength of ceramic materials and achieving a breakthrough improvement in the hydrostatic pressure resistance of the curved disk transducer.

[0007] The technical solution of this invention is to provide a curved disk transducer that utilizes deformation in the thickness direction of ceramic, comprising:

[0008] A disc-shaped internal support plate, wherein the internal support plate has a hollow structure;

[0009] Multiple piezoelectric ceramic stacks are evenly spaced along the circumferential direction of the internal support plate, and the thickness direction of the piezoelectric ceramic stacks is arranged radially along the internal support plate and located on the outside of the internal support plate.

[0010] The polarization direction of the piezoelectric ceramic stack is consistent with its thickness direction;

[0011] The outer side of the internal support plate is provided with a first radial limiting part and a second radial limiting part corresponding to each piezoelectric ceramic stack; the first radial limiting part and the second radial limiting part are used to limit the two ends of the piezoelectric ceramic stack in the thickness direction respectively; and the radial distance between the first radial limiting part and the second radial limiting part is slightly smaller than the free length of the piezoelectric ceramic stack in its thickness direction, so that each piezoelectric ceramic stack is subjected to radial pre-compression stress during installation.

[0012] When the transducer is working, the pre-compressed and fixed piezoelectric ceramic stack undergoes expansion and contraction along its thickness direction under the excitation of an alternating electric field. This deformation drives the internal support plate to generate axial bending vibration.

[0013] Preferably, the radial structure consisting of the piezoelectric ceramic stack and the internal support plate is symmetrically distributed vertically in the axial direction of the internal support plate, forming a double-sided radial structure.

[0014] Preferably, the internal support plate is formed by connecting upper and lower support plates. The inner outer edges of the upper and lower support plates have bosses that can connect with each other. After the bosses are connected, a cavity is formed in the internal support plate, providing space for the vibration and deformation of the internal support plate.

[0015] Preferably, the first radial limiting part is located in the central region outside the inner support plate. The first radial limiting part is a polygonal prism that protrudes outward in the axial direction of the inner support plate. The number of sides of the polygonal prism is the same as the number of piezoelectric ceramic stacks. The sides of each polygonal prism correspond to and abut against the inner ends of each piezoelectric ceramic stack.

[0016] Preferably, the second radial limiting part includes a plurality of positioning structures disposed on the outside of the inner support plate, distributed along the circumference and corresponding one-to-one with the outer end of the piezoelectric ceramic stack. The positioning structure is a groove or a boss, and the outer end of the piezoelectric ceramic stack is embedded in or abuts against the annular groove or annular boss.

[0017] Preferably, each piezoelectric ceramic stack consists of multiple piezoelectric ceramic sheets stacked along the thickness direction, with adjacent piezoelectric ceramic sheets having opposite polarization directions and being connected in series or parallel via electrodes.

[0018] Preferably, the package also includes a housing, in which the internal support plate and the piezoelectric ceramic stack are sealed and installed, and at least one surface of the housing is a radiating surface made of a sound-permeable material.

[0019] Preferably, under hydrostatic pressure, the inward concave deformation of the internal support plate is converted into additional compressive stress on the piezoelectric ceramic stack along its thickness direction.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] This invention utilizes the phase transition in the thickness direction of ceramics to drive the bending vibration of a circular plate. Under the same working conditions, it can significantly increase the working depth of the bending disc by taking advantage of the strong pressure resistance of ceramics. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 This is a cross-sectional view of the present invention;

[0024] Figure 3 This is a schematic diagram of the internal support plate of the present invention;

[0025] Figure 4 This is a schematic diagram of the piezoelectric ceramic stack structure of the present invention.

[0026] In the diagram: 1. Internal support plate; 2. Piezoelectric ceramic stack; 11. Hexagonal prism; 12. Groove. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0028] A curved disk transducer utilizing deformation in the thickness direction of ceramic, referenced Figure 1-4 It includes a disc-shaped internal support plate 1 and six piezoelectric ceramic stacks 2. The internal support plate 1 has a hollow structure. The piezoelectric ceramic stacks 2 are evenly spaced along the circumference of the internal support plate 1, and the thickness direction of the piezoelectric ceramic stacks 2 is arranged radially along the internal support plate 1 and located on the outside of the internal support plate. The polarization direction of the piezoelectric ceramic stacks 2 is consistent with its thickness direction.

[0029] In this embodiment, the internal support plate 1 is made of a metal with good elasticity and strength, such as titanium alloy. The internal support plate 1 is formed by joining two metal plates, upper and lower. The inner outer edges of the upper and lower metal plates have bosses that can be joined together. After the bosses are joined, a cavity is formed inside the internal support plate 1, providing space for the vibration and deformation of the internal support plate. The piezoelectric ceramic stack 2 is formed by stacking multiple rectangular or square piezoelectric ceramic sheets along the thickness direction and bonding them together with epoxy resin. The polarization directions of adjacent piezoelectric ceramic sheets are opposite, and they are connected in series or parallel through internal electrodes, so that when a voltage is applied to both ends of the entire piezoelectric ceramic stack, all ceramic sheets expand and contract synchronously along the thickness direction (i.e., the stacking direction).

[0030] The outer side of the internal support plate 1 is provided with a first radial limiting part and a second radial limiting part corresponding to each piezoelectric ceramic stack 2. The first and second radial limiting parts are used to limit the two ends of the piezoelectric ceramic stack 2 in the thickness direction, namely the inner end near the center of the internal support plate and the outer end radially away from its center. Furthermore, the radial distance between the first and second radial limiting parts is less than the free length of the piezoelectric ceramic stack 2 in its thickness direction, so that each piezoelectric ceramic stack 2 is subjected to radial pre-compression stress during installation. In this way, after bonding and curing, the piezoelectric ceramic stack 2 is slightly compressed, generating a radial pre-compression stress. This pre-stress ensures a firm connection and puts the piezoelectric ceramic stack in a compressed state even in a static state.

[0031] When the transducer is working, the pre-compressed and fixed piezoelectric ceramic stack 2 undergoes expansion and contraction along its thickness direction under the excitation of an alternating electric field. This deformation drives the internal support plate 1 to generate axial bending vibration.

[0032] This embodiment also includes a housing and lead-out cables to form a complete transducer. The internal support plate 1 and the piezoelectric ceramic stack 2 are sealed and installed within the housing. At least one surface of the housing is a radiating surface made of acoustically transparent material. In deep water, the transducer indents inward under hydrostatic pressure, which is converted into compressive force along the length of the piezoelectric ceramic stack. The ceramic itself has a compressive strength far exceeding its tensile strength, thus enabling deep-sea operation.

[0033] In one implementation, the radiating structure composed of the piezoelectric ceramic stack 2 and the internal support plate 1 is symmetrically distributed vertically in the axial direction of the internal support plate 1, forming a double-sided radiating structural feature.

[0034] In one embodiment, the first radial limiting part is located in the central region outside the inner support plate 1. In this embodiment, the first radial limiting part is a hexagonal prism 11 that protrudes outward in the axial direction of the inner support plate 1. The number of sides of the hexagonal prism 11 is the same as the number of piezoelectric ceramic stacks. In this way, the six sides of the hexagonal prism 11 correspond to the inner end of a piezoelectric ceramic stack and abut against each other to achieve positioning and limiting.

[0035] Correspondingly, in one embodiment, the second radial limiting part includes a plurality of positioning structures located on the outside of the inner support plate 1, distributed along the circumference and corresponding one-to-one with the outer end of the piezoelectric ceramic stack 2. The positioning structure is a groove 12 adapted to the outer end, used for precise positioning and installation of the piezoelectric ceramic stack 2, and the outer end of the piezoelectric ceramic stack 2 is embedded in the groove 12.

[0036] In one implementation, under hydrostatic pressure, the inward concave deformation of the internal support plate 1 is converted into additional compressive stress on the piezoelectric ceramic stack 2 along its thickness direction.

[0037] Working Principle: When an alternating voltage is applied to the two poles of the piezoelectric ceramic stack 2, due to the inverse piezoelectric effect, each piezoelectric ceramic stack 2 undergoes synchronous expansion and contraction vibration along its thickness direction. The synchronous radial expansion and contraction of all piezoelectric ceramic stacks together apply a periodic radial compression and expansion force to the disc-shaped internal support plate 1. This periodic radial force excites the bending vibration mode of the internal support plate 1, causing it to reciprocate along the axial direction like a diaphragm, thereby radiating sound waves into the water through the sound-transmitting radiation surface, achieving the transmission function. Conversely, when external sound waves act on the radiation surface, causing the support plate 1 to bend and vibrate, it will drive the piezoelectric ceramic stack to undergo thickness deformation, generating a voltage signal, achieving the reception function.

[0038] Pressure Resistance Principle: When the transducer of this invention is placed in deep water, the hydrostatic pressure acts uniformly on the sound-transmitting radiation surface and is transmitted to the internal support plate 1. The hydrostatic pressure causes the internal support plate to undergo inward concave deformation, which leads to a decrease in the radial distance between the two points fixing the piezoelectric ceramic stack on the internal support plate. Since the piezoelectric ceramic stack is pre-compressed and installed between these two points, the inward deformation of the internal support plate further compresses the piezoelectric ceramic stack, increasing the compressive stress it bears. Throughout the process, the piezoelectric ceramic stack is always under pressure. Because piezoelectric ceramic materials (such as PZT) have extremely high compressive strength (up to hundreds of MPa) and very low tensile strength (typically only tens of MPa), this invention cleverly transforms harmful hydrostatic pressure into compressive stress beneficial to the drive element, thereby fundamentally solving the fatal weakness of traditional curved disk transducers that are easily damaged by ceramic tension, and realizing the ability to operate in deep water.

[0039] In summary, this invention revolutionizes the driving and force-bearing principles of traditional curved disk transducers. In deep-water environments, hydrostatic pressure causes the internal support plate to indent inward, and this deformation is directly converted into axial compressive force on the circumferentially arranged piezoelectric ceramic stack. Piezoelectric ceramic materials possess extremely high compressive strength (typically an order of magnitude higher than tensile strength), therefore this structure can withstand hydrostatic pressure far exceeding that of traditional structures, enabling operating depths of hundreds of meters or even deeper, greatly expanding the application range of curved disk transducers.

[0040] The above description only illustrates preferred embodiments of the present invention and should not be construed as limiting the scope of the claims. Any equivalent procedural modifications made using this specification are included within the patent protection scope of this invention.

Claims

1. A curved disk transducer utilizing deformation in the thickness direction of ceramic, characterized in that, include: A disc-shaped internal support plate, wherein the internal support plate has a hollow structure; Multiple piezoelectric ceramic stacks are evenly spaced along the circumferential direction of the internal support plate, and the thickness direction of the piezoelectric ceramic stacks is arranged radially along the internal support plate and located on the outside of the internal support plate. The polarization direction of the piezoelectric ceramic stack is consistent with its thickness direction; The outer side of the internal support plate is provided with a first radial limiting part and a second radial limiting part corresponding to each piezoelectric ceramic stack; the first radial limiting part and the second radial limiting part are used to limit the two ends of the piezoelectric ceramic stack in the thickness direction respectively; and the radial distance between the first radial limiting part and the second radial limiting part is less than the free length of the piezoelectric ceramic stack in its thickness direction, so that each piezoelectric ceramic stack is subjected to radial pre-compression stress during installation. When the transducer is working, the pre-compressed and fixed piezoelectric ceramic stack undergoes expansion and contraction along its thickness direction under the excitation of an alternating electric field. This deformation drives the internal support plate to generate axial bending vibration.

2. The curved disk transducer utilizing ceramic thickness deformation according to claim 1, characterized in that: The radial structure consisting of the piezoelectric ceramic stack and the internal support plate is symmetrically distributed vertically along the axial direction of the internal support plate, forming a double-sided radial structure.

3. The curved disk transducer utilizing ceramic thickness deformation according to claim 1, characterized in that: The internal support plate is formed by connecting upper and lower support plates, and the inner outer edges of the upper and lower support plates have protrusions that can connect with each other.

4. The curved disk transducer utilizing ceramic thickness deformation according to claim 1, characterized in that: The first radial limiting part is located in the central region outside the inner support plate. The first radial limiting part is a multi-faceted prism that protrudes outward in the axial direction of the inner support plate. The number of the sides of the multi-faceted prism is the same as the number of the piezoelectric ceramic stacks. The sides of each multi-faceted prism correspond to and abut against the inner end of each piezoelectric ceramic stack.

5. The curved disk transducer utilizing ceramic thickness deformation according to claim 4, characterized in that: The second radial limiting part includes a plurality of positioning structures disposed on the outside of the internal support plate, distributed along the circumference and corresponding one-to-one with the outer end of the piezoelectric ceramic stack. The positioning structure is a groove or a boss, and the outer end of the piezoelectric ceramic stack is embedded in or abuts against the groove or boss.

6. The curved disk transducer utilizing ceramic thickness deformation according to claim 1, characterized in that: Each of the piezoelectric ceramic stacks consists of multiple piezoelectric ceramic sheets stacked along the thickness direction, with adjacent piezoelectric ceramic sheets having opposite polarization directions and being connected in series or parallel via electrodes.

7. The curved disk transducer utilizing ceramic thickness deformation according to claim 1, characterized in that: It also includes a packaging housing, in which the internal support plate and the piezoelectric ceramic stack are sealed and installed, and at least one disk surface of the packaging housing is a radiating surface made of sound-permeable material.

8. The curved disk transducer utilizing ceramic thickness deformation according to claim 1, characterized in that: Under hydrostatic pressure, the inward concave deformation of the internal support plate is converted into additional compressive stress on the piezoelectric ceramic stack along its thickness direction.

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