Piezoelectric Pressure Sensor Preload Application via Pressing Mechanism

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Solution Overview

Problem

Existing pressure sensors face challenges in accurately applying a preload to piezoelectric elements due to variations in machining accuracy of screw threads, leading to inconsistencies in pressure detection accuracy.

Innovation Solution

A method for manufacturing pressure sensors that involves a tubular housing with a support plate and a rod-shaped transmission section, where the piezoelectric element is pressed against the support plate to apply a predetermined preload, ensuring accurate transmission of pressure without deforming the diaphragm, and laser welding is used to fix the transmission section to the diaphragm with specific incident angles to maintain sensitivity consistency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a screw is used to apply preload to the piezoelectric element, then the preload can be applied from the rear end side, but the machining accuracy variations of the screw thread cause inaccurate preload application

Engineering Contradiction:

Improvepreload application methodVSAvoidpreload accuracy

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent replaces the screw-thread mechanical system with a pressing mechanism consisting of a pressing member and pressing portion. This substitution eliminates the dependency on screw thread machining accuracy, thereby achieving more accurate and consistent preload application to the piezoelectric element without the inaccuracies introduced by threaded fastening systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a pressing member as an intermediary component that transfers force from the transmission section to the piezoelectric element. This intermediary mechanism provides a more reliable and accurate method of applying preload compared to direct screw fastening, as it allows for controlled pressing force without the cumulative errors of threaded connections.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the transmission section is fixed to the housing after accommodating the piezoelectric element, then the assembly process is simplified, but the preload accuracy is compromised due to diaphragm deformation

Engineering Contradiction:

Improveassembly efficiencyVSAvoidpreload accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies the preliminary action principle by first fixing the transmission section to the housing before accommodating the piezoelectric element. This sequence ensures that the transmission section is already in its final position and the diaphragm is properly positioned, eliminating the risk of diaphragm deformation during subsequent assembly steps while maintaining efficient production flow.

Inventive Principle:

Principle #10Preliminary action

3Force

If the diaphragm is deformed during preload application, then the piezoelectric element can be pressed against the support plate, but the pressure detection accuracy is reduced

Engineering Contradiction:

Improvepreload force applicationVSAvoidpressure detection accuracy

Core Design Contradiction:

ForceVSMeasurement precision

Solution Approach 1:

The patent applies local quality by providing a dedicated pressing portion on the transmission section that concentrates the pressing force precisely on the piezoelectric element. This localized force application ensures uniform preload distribution on the piezoelectric element without causing deformation to the diaphragm, thereby maintaining both effective force application and measurement precision.

Inventive Principle:

Principle #3Local quality

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 approach allows for precise application and maintenance of preload to the piezoelectric element, enhancing the accuracy of pressure detection and reducing sensitivity variations in the pressure sensor, thereby improving overall detection accuracy.

Implementation Method 1

a piezoelectric element to which the pressure received by the diaphragm is transferred is disposed in the housing

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

laser welding is used to fix the transmission section to the diaphragm with specific incident angles

Methodology Applied

Scientific EffectLaser welding: Laser Beam Welding

Data Source

PatentEP3096121B1Method of manufacturing pressure sensor and pressure sensor

Publication Date: 2019.11.06 NITERRA CO LTD

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AI summary

A method of manufacturing a pressure sensor including a tubular housing having a lid-shaped support plate formed at one end of the housing, a diaphragm, a piezoelectric element for outputting an electrical signal corresponding to pressure received by the diaphragm, and a rod-shaped transmission section for transmitting the pressure to the piezoelectric element. The method includes the steps of accommodating the piezoelectric element into the housing, and fixing the transmission section to the housing through the diaphragm in a state in which a predetermined preload is applied to the piezoelectric element in an axial direction of the housing by pressing the piezoelectric element against the support plate by the transmission section.