Tire Sensor Module Piezoelectric Layout for Directional Deformation Sensing

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Solution Overview

Problem

Piezoelectric sensors in tire sensor modules face challenges in measuring deformation with high sensitivity and accuracy due to the influence of deformations in directions other than the specific direction being measured, and the sealing of sheet-like piezoelectric sensors with mold resin reduces detection sensitivity.

Innovation Solution

A composite piezoelectric element with a first and second electrode layer and a piezoelectric substance layer, featuring buffer portions without the piezoelectric substance layer, enhances anisotropy in measurement sensitivity by using belt-like portions and cutouts to isolate non-specific direction deformations, and a buffer portion with a soft modulus to prevent deformation inhibition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If piezoelectric films are disposed in different directions to measure deformation in different directions, then the measurement coverage is improved, but the measurement precision in a specific direction deteriorates due to influence from deformations in other directions

Engineering Contradiction:
Improvemeasurement coverageVSAvoidmeasurement precision in specific direction
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The piezoelectric film is divided into multiple independent piezoelectric elements arranged in a matrix pattern. Each element independently measures deformation in its specific orientation direction, and the control unit processes signals from individual elements to determine deformation in specific directions, thereby eliminating cross-directional interference while maintaining comprehensive measurement coverage.

Inventive Principle:
Principle #1Segmentation

2Reliability

If sheet-like piezoelectric sensor is sealed with mold resin to protect it, then the reliability is improved, but the detection sensitivity deteriorates due to inhibition of deformation

Engineering Contradiction:
Improveprotection of piezoelectric sensorVSAvoiddetection sensitivity
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The mold resin is configured with locally varying properties: it has a first region with higher hardness near the piezoelectric sensor to provide protection, and a second region with lower hardness away from the sensor to minimize deformation inhibition. This gradient hardness structure allows the resin to simultaneously protect the sensor while maintaining its deformation detection sensitivity.

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

The solution allows for high sensitivity and accuracy in measuring deformation in specific directions while reducing noise from other directions, improving the detection sensitivity of tire deformation.

Implementation Method 1

a piezoelectric substance layer (13) disposed on the first electrode layer (12), and a second electrode layer (14) disposed on the piezoelectric substance layer (13)... the piezoelectric sensor (81) measures deformation of a tire... converting the deformation (deformation speed) generated in the tire to voltage

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP3901565B1Tire sensor module and tire sensor
Publication Date: 2023.10.18 ALPS ALPINE CO LTD
  • EP3901565B1 patent drawingFigure 1(a)~1(c)
  • EP3901565B1 patent drawingFigure 2(a)~2(c)
  • EP3901565B1 patent drawingFigure 3(a)~3(c)

AI summary

To provide a composite piezoelectric element configured to measure deformation generated in a specific direction with high sensitivity and accuracy and a tire-condition measuring apparatus including the composite piezoelectric element, a composite piezoelectric element 10 includes a first electrode layer 12, a piezoelectric substance layer 13 disposed on the first electrode layer 12, and a second electrode layer 14 disposed on the piezoelectric substance layer 13, wherein, in plan view, a measuring unit 15 including the first electrode layer 12, the piezoelectric substance layer 13, and the second electrode layer 14 and a buffer portion 16 in which the piezoelectric substance layer 13 is not provided are provided.