Ultrasonic Transducer Acoustic Coupling Layer Thickness Control

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Solution Overview

Problem

The existing ultrasonic transducers face challenges in accurately controlling the thickness of the acoustic coupling layer, particularly when using fluid or easily deformable materials, which can lead to thinning due to the weight of the piezo element during assembly or operation, affecting acoustic efficiency and noise levels.

Innovation Solution

The piezo element is fixed to the housing at a second face opposite the acoustic coupling layer, ensuring a constant thickness by having the housing abut the acoustic window, with a distance control feature maintaining the intended thickness, even when using fluid or adhesive materials, allowing for deformation during operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the piezo element is directly attached to the acoustic window, then assembly is simplified, but the acoustic coupling layer thickness cannot be controlled

Engineering Contradiction:
Improveassembly simplicityVSAvoidacoustic coupling layer thickness control
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent introduces a housing as an intermediary component between the piezo element and acoustic window. The housing includes a piezo element holder and an acoustic window holder that are detachably connected, allowing the piezo element to be mounted in the holder before final assembly. This intermediary structure enables precise thickness control of the acoustic coupling layer while maintaining assembly simplicity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the piezo element weight is used to press the acoustic coupling layer, then acoustic contact is improved, but the coupling layer thickness decreases below intended level

Engineering Contradiction:
Improveacoustic contact qualityVSAvoidacoustic coupling layer thickness
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-setting the acoustic coupling layer thickness during the assembly process using the housing structure as a spacer. The housing is designed with precise dimensions to maintain the intended thickness of the acoustic coupling layer before the piezo element is fully assembled, preventing thickness reduction that would otherwise occur under the piezo element's weight during operation.

Inventive Principle:
Principle #10Preliminary action

3Stability of the object's composition

If the piezo element is fixed at both faces, then positioning stability is improved, but the piezo element cannot deform during operation

Engineering Contradiction:
Improvepiezo element positioning stabilityVSAvoidpiezo element deformation capability
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent segments the fixation points of the piezo element, fixing it only at the peripheral region rather than the entire surface. The piezo element is secured at its peripheral region to the piezo element holder, while the central active area remains free to deform during ultrasonic operation. This segmented fixation approach maintains positioning stability while preserving the necessary deformation capability for ultrasonic signal generation.

Inventive Principle:
Principle #1Segmentation

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

This solution ensures a consistent and effective acoustic coupling layer thickness, enhancing the ultrasonic transducer's efficiency and lifespan by preventing displacement and thinning, even with fluid or adhesive materials, while allowing for the necessary deformation of the piezo element.

Implementation Method 1

the ultrasonic transducer comprises an active vibrating element in the form of a piezo element to translate electric signals to ultrasonic signals and vice versa

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

an acoustic coupling layer, wherein the acoustic coupling layer is arranged between the acoustic window and a first face of the piezo element

Methodology Applied
Scientific EffectAcoustic transmission: Sound

Data Source

PatentEP3178570B1Ultrasonic transducer and method for manufacturing an ultrasonic transducer
Publication Date: 2019.01.30 DANFOSS AS
  • EP3178570B1 patent drawingFigure 1

AI summary

The invention relates to an ultrasonic transducer (1), comprising a piezo element (4), an acoustic window (9), a housing (2) and an acoustic coupling layer (5). The acoustic coupling layer (5) is arranged between the acoustic window (9) and a first face (8) of a piezo element (4). In order to ensure a constant thickness of the acoustic coupling layer (5) the piezo element (4) is fixed to the housing (2) at a second face (11) of the piezo element (4) opposite the acoustic layer (5). Furthermore, the housing (2) abuts the acoustic window (9) to ensure a constant thickness of the acoustic coupling layer (5) between the first face (8) and the acoustic window (9) in the resting position of the piezo element (4).