Contoured Diaphragm Strain Sensor for Accurate Force Measurement
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Solution Overview
Problem
Traditional diaphragm strain sensors require precise placement of strain gauges to measure peak compression and tension strains accurately, leading to low sensitivity and reduced signal output due to the concentration of strains at radially narrow locations.
Innovation Solution
A contoured diaphragm with varying thickness, where the thickness increases with radial distance from the center, spreading peak compression and tension strains across wider regions, allowing strain gauges to be placed with less precision for accurate force measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are placed at radially narrow locations to measure peak strains, then measurement precision is improved, but device complexity increases due to precise placement requirements
Solution Approach 1:
The patent applies local quality by creating a contoured diaphragm with non-uniform thickness distribution. The diaphragm has a thinned intermediate region between the inner and outer support regions, which concentrates strains in specific localized areas. This allows strain gauges to be placed at these concentrated strain locations to achieve accurate measurements without requiring extremely precise placement, as the strain concentration is built into the diaphragm geometry itself.
Solution Approach 2:
The patent changes the geometric parameter of the diaphragm thickness to solve the contradiction. By varying the thickness of the diaphragm across different radial regions (thinner in the intermediate region, thicker at support regions), the strain distribution is modified. This parameter change creates wider regions of peak strain that are easier to locate and measure, reducing the placement precision requirements while maintaining measurement accuracy.
2Measurement precision
If strain gauges are placed at radially narrow locations, then measurement precision is improved, but ease of operation deteriorates due to difficulty in precise placement
Solution Approach 1:
The contoured diaphragm creates localized strain concentration in the intermediate region, providing distinct and wider areas where peak strains occur. This makes it easier for operators to identify and place strain gauges at the correct locations without requiring extremely precise positioning, thereby improving ease of operation while maintaining measurement precision.
Solution Approach 2:
The diaphragm geometry is pre-designed with specific thickness variations that create predictable strain concentration patterns before the strain gauges are installed. This preliminary structuring of the strain distribution allows operators to easily locate the optimal gauge placement areas without complex calculations or iterative adjustments, simplifying the installation process.
3Manufacturing precision
If the diaphragm has uniform thickness, then manufacturing precision is improved, but measurement precision deteriorates due to strain concentration at narrow locations
Solution Approach 1:
The patent deliberately introduces non-uniform thickness distribution in the diaphragm, with the intermediate region thinned relative to the inner and outer support regions. This local variation in thickness creates wider regions of peak strain in the intermediate area, which improves force measurement accuracy. The manufacturing process must accommodate this controlled non-uniformity, but it enables better measurement performance.
Solution Approach 2:
The patent changes the thickness parameter of the diaphragm from uniform to non-uniform, with specific regions (inner support, outer support, and intermediate) having different thickness values. This parameter change optimizes the strain distribution to create wider peak strain regions, improving measurement precision while the manufacturing process is adapted to produce this controlled thickness variation.
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 contoured diaphragm design enhances the accuracy of force measurement by distributing strain across wider areas, reducing the need for precise gauge placement and improving sensitivity.
Implementation Method 1
Strain gauges (not shown) are disposed upon the diaphragm at radial locations matched to the inner and outer dashed lines 114, 116, to sense strain imparted to the diaphragm due to the deflection.
Data Source
AI summary
A force sensor includes an annular diaphragm that includes an inner perimeter and an outer perimeter; the diaphragm has an outer annular portion having a tapered thickness that increases with decreasing radial distance from the outer perimeter; the diaphragm has an inner annular portion having a tapered thickness that increases with decreasing radial distance from the inner perimeter; a first strain gauge at the outer annular portion; and a second strain gauge at the inner annular portion.