Force Sensing Bridge Portion for Uniform Piezoelectric Stress Distribution
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Solution Overview
Problem
Conventional force sensing apparatuses using strain gauges face accuracy issues due to adhesive variability with temperature and low response speed, while piezoelectric sensors are fragile and have low reliability.
Innovation Solution
A force sensing apparatus design featuring a bridge portion with varying thicknesses in its cases and connecting components, which includes a first and second case with annular and bridge portions, and a force sensing module positioned in a space between them, utilizing electrically conductive and piezoelectric layers stacked alternately to distribute forces uniformly and prevent stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauge is used to measure force, then measurement can be performed, but measurement accuracy deteriorates due to adhesive variability with temperature and low response speed
Solution Approach 1:
The patent replaces the adhesive-based mechanical bonding system with a direct mechanical connection system. The force sensing module is directly connected to the test object through rigid connecting components, eliminating the adhesive layer that causes temperature-dependent variability and buffering effects. This substitution resolves the contradiction by removing the source of measurement inaccuracy while maintaining reliable force transmission.
2Speed
If piezoelectric material is used to measure force in real time, then response speed and sensitivity improve, but reliability deteriorates due to fragility
Solution Approach 1:
The patent incorporates a cushioning structure that protects the fragile piezoelectric material from external impacts and stress concentrations before damage can occur. The bridge portion and connecting components are designed with appropriate thicknesses and geometries to distribute forces uniformly, preventing sudden impacts from damaging the piezoelectric layers. This beforehand protection allows the use of fragile piezoelectric materials while maintaining system reliability.
Solution Approach 2:
The patent optimizes the thickness parameters of the bridge portion and connecting components to achieve optimal force distribution. By carefully selecting and adjusting these dimensional parameters, the structure can accommodate the fragile piezoelectric material while providing sufficient mechanical protection, thus changing the physical parameters of the supporting structure to protect the sensitive sensing element.
3Measurement precision
If adhesive is used to adhere strain gauge to object, then force measurement can be performed, but measurement accuracy deteriorates due to adhesive buffering effect
Solution Approach 1:
The patent extracts and removes the adhesive layer from the force measurement system entirely. By eliminating this intermediate layer, the direct mechanical connection between the force sensing module and the test object is achieved, removing the buffering effect that delayed the response speed and compromised measurement accuracy. This extraction resolves both the accuracy and response speed issues simultaneously.
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 enhances the reliability and accuracy of force measurement by uniformly distributing forces and preventing stress concentration on the piezoelectric layers, thus improving the sensitivity and response speed of the force sensing apparatus.
Implementation Method 1
utilizing electrically conductive and piezoelectric layers stacked alternately
Data Source
AI summary
A force sensing apparatus with bridge portion comprises a first case, a second case, and a force sensing module. The first case comprises a first annular portion, a first bridge portion, and an inner wall portion. The first bridge portion is connected to an outer periphery of the first annular portion. The inner wall portion is connected to an inner periphery of the first annular portion. The second case comprises a second annular portion, a second bridge portion, and an outer wall portion. The second bridge portion is connected to an inner periphery of the second annular portion. The outer wall portion is connected to an outer periphery of the second annular portion. A stiffness of the second annular portion along an axial direction is greater than a stiffness of the second bridge portion along the axial direction. The second case is disposed on the first case along the axial direction to form a space. The force sensing module is disposed in the space.