Ultrasonic Transducer λ/4 Oscillator with Flexible Bearing
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Solution Overview
Problem
λ/2 thickness oscillators used in ultrasonic transducers for vehicles are excessively long, which impedes transverse contraction of the piezoceramic disk when attached to a substrate, leading to decreased sensitivity.
Innovation Solution
A λ/4 thickness oscillator design with a bearing structure that allows transverse strain of the piezoelectric element by using rod-shaped support elements with low transverse stiffness, connected to the housing to prevent impediment of transverse contraction, ensuring secure mechanical attachment without compromising sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a λ/2 thickness oscillator design is used, then the transducer has sufficient sensitivity, but the transducer becomes excessively long
Solution Approach 1:
The transducer is segmented into two functional parts: a λ/4 thickness oscillator for compact size and a separate bearing structure (support device) that provides mechanical stability. This segmentation allows the oscillator itself to be short while the overall system maintains the necessary mechanical properties through the support structure.
Solution Approach 2:
A bearing structure acts as an intermediary between the λ/4 piezoelectric oscillator and the housing/substrate. This intermediary component (support device with bearing elements) enables the oscillator to maintain its compact λ/4 length while providing the necessary mechanical support and allowing transverse contraction, thus mediating between the conflicting requirements of short length and mechanical stability.
2Stability of the object's composition
If the piezoelectric element is rigidly attached to the substrate, then mechanical stability is improved, but transverse contraction is impeded reducing sensitivity
Solution Approach 1:
The bearing structure provides different mechanical properties at different locations and directions: it provides rigid support in the thickness direction (perpendicular to the piezoelectric element surfaces) to maintain mechanical stability, while providing compliance in the transverse direction (parallel to the surfaces) to allow necessary contraction and maintain sensitivity.
Solution Approach 2:
The bearing elements are designed with specific geometric parameters (rod-shaped with particular length-to-diameter ratios) that create anisotropic mechanical properties - high stiffness in the thickness direction and low stiffness in the transverse direction. This parameter optimization allows simultaneous achievement of mechanical stability and sensitivity.
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 design maintains the compact size of a λ/4 thickness oscillator while achieving sensitivity comparable to a λ/2 oscillator, minimizing transverse strain impediment and ensuring durable mechanical connection.
Implementation Method 1
an oscillating structure (150, 175) including at least one preferably disk-shaped piezoelectric element (150, 175)
Implementation Method 2
an electroacoustic transducer for generating thickness mode oscillations
Data Source
AI summary
An electroacoustic transducer includes: a housing; an oscillating structure including at least one disk-shaped piezoelectric element having first and second surfaces; an acoustic transmitter; and electrical connecting element contacting electrodes of the piezoelectric element. The acoustic transmitter has parallel first and second surfaces, which first surface is joined to the first surface of the piezoelectric element, and which second surface is suitable for emitting and/or receiving sound waves. The distance between the second surface of the acoustic transmitter and the second surface of the piezoelectric element corresponds to ¼ of the resonance oscillation wavelength of the oscillating structure. The piezoelectric element is connected to the housing with the aid of a bearing structure which allows transverse strains of the piezoelectric element.