Nested Piezoelectric Actuator Structure for Stronger Tonpilz Transducers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional Tonpilz design-based underwater acoustic transducers with PZT piezoelectric ceramic stacks suffer from low transverse piezoelectric performance and bending strength, leading to potential damage during use.
Innovation Solution
The use of piezoelectric actuator with reinforced structures, including a square pipe construction of successively adjoining single crystal piezoelectric elements and a prestressing mechanism, enhances bending strength and damage resistance by mutual support between outer and inner piezoelectric assemblies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thin and long single crystal piezoelectric elements are used to achieve high transverse piezoelectric performance, then the piezoelectric performance is improved, but the bending strength decreases making the crystals easily damaged
Solution Approach 1:
The patent employs a nested structure where an inner piezoelectric assembly is placed inside an outer piezoelectric assembly. The inner assembly includes inner piezoelectric elements that are thinner and longer for high transverse piezoelectric performance, while the outer assembly provides structural reinforcement. This nested configuration allows the inner fragile elements to benefit from the protective framework of the outer assembly, resolving the contradiction between achieving high piezoelectric performance and maintaining sufficient bending strength.
Solution Approach 2:
The patent creates a composite structure by combining inner and outer piezoelectric assemblies with different structural characteristics. The outer assembly uses thicker, shorter piezoelectric elements that provide mechanical strength, while the inner assembly uses thinner, longer elements optimized for piezoelectric performance. This composite approach integrates materials and structures with complementary properties to simultaneously achieve both high performance and adequate strength.
2Power
If PZT piezoelectric ceramic stacks are used in traditional Tonpilz design, then the transducer can generate acoustic waves, but the transverse piezoelectric effect is weak leading to low sounding efficiency and acoustic source level
Solution Approach 1:
The patent changes the piezoelectric mode from longitudinal (d33) to transverse (d31) by reconfiguring the piezoelectric element geometry and electrode arrangement. The inner piezoelectric assembly uses thinner elements with electrodes positioned to exploit the transverse piezoelectric effect, which has higher coupling coefficients. This parameter change in the piezoelectric mode fundamentally improves the electromechanical coupling and acoustic source level while maintaining reliable operation.
3Device complexity
If no strengthening measure is taken for thin and long single crystals, then the device structure remains simple, but the single crystals would easily be damaged during use
Solution Approach 1:
The nested assembly structure provides inherent strengthening without requiring complex external reinforcement. The outer piezoelectric assembly acts as a protective framework that mechanically supports the inner piezoelectric elements. This nested configuration naturally prevents the thin and long single crystals from experiencing excessive bending stresses during operation, thereby improving damage resistance while maintaining relatively simple device structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The reinforced piezoelectric actuator significantly improves bending and breakage resistance, enabling more effective acoustic wave generation and increased durability for underwater acoustic transducers.
Implementation Method 1
The piezoelectric stack produces, under the effect of the drive voltage, an axial stretching vibration, such that the piston produces corresponding vibrations for radiating acoustic waves toward water
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A piezoelectric actuator (100) and an underwater acoustic transducer based on this actuator, so as to solve technical problems existing in the prior art regarding low bending and twisting strength and easy damageability of a transducer driven by transverse mode single crystal piezoelectric elements. The piezoelectric actuator (100) comprises an outer piezoelectric assembly and an inner piezoelectric assembly arranged in the internal of the outer piezoelectric assembly, wherein the outer piezoelectric assembly comprises four outer piezoelectric elements (110), with the four outer piezoelectric elements (110) successively adjoining each other along their axial-length edges to form a square pipe construction; and the inner piezoelectric assembly comprises a plurality of inner piezoelectric elements (120), wherein the cut, the length and the thickness of the inner piezoelectric assembly are the same as those of the outer piezoelectric assembly, while its circumferential length thereof is smaller than that of the outer piezoelectric assembly, and an axial-length edge or an outer surface of the inner piezoelectric assembly is in connection with and bonded onto an inner surface of the outer piezoelectric element, to provide mutual support between the outer piezoelectric assembly and the inner piezoelectric assembly and accordingly, significantly improve the overall bending and breakage resistance of the piezoelectric actuator (100). An underwater projector of Tonpilz design using a piezoelectric actuator (100) as its motor section is also described.