Angular Acceleration Sensor Beam Stress Detection
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Solution Overview
Problem
Existing angular acceleration sensors and acceleration sensors face low sensitivity due to the inability to efficiently detect maximum flexure stress generated in a beam, as piezoresistors are typically placed at the center or deviated from the center, resulting in suboptimal stress detection.
Innovation Solution
The design includes a beam with a flat plate portion, a central projection, and end-side projections, with detection elements positioned at non-central locations to maximize flexure stress detection, forming a bridge circuit to enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If piezoresistors are disposed at the center of the beam in the lengthwise direction, then the structure is simple and manufacturing is easy, but the sensitivity of the angular acceleration sensor is low because maximum flexure stress cannot be detected
Solution Approach 1:
The beam is designed with non-uniform cross-sectional area along its length, creating regions of different stiffness. The detection elements are positioned at specific locations where the beam's flexure stress is maximized due to this non-uniform structure, allowing optimal stress detection without requiring piezoresistors at the geometric center
Solution Approach 2:
The invention introduces a new dimension to the beam structure by adding projections that extend in the widthwise direction. This creates a three-dimensional stress distribution pattern where maximum stress occurs at specific non-central locations, enabling improved sensitivity while maintaining manufacturing simplicity
2Measurement precision
If piezoresistors are disposed at positions deviated from the center of the beam, then sensitivity may be improved, but the manufacturing precision requirements increase and the structure becomes more complex
Solution Approach 1:
The beam's non-uniform cross-sectional area creates localized stress concentration regions at predictable positions. The detection elements are placed at these predetermined locations where the non-uniform structure naturally generates maximum flexure stress, achieving high sensitivity without requiring high-precision positioning relative to the beam's geometric center
Solution Approach 2:
The cross-sectional area of the beam is varied along its length to change the stress distribution pattern. This parameter modification creates a new stress profile where maximum stress occurs at non-central positions, allowing detection elements to be placed at optimized locations that improve sensitivity while simplifying manufacturing tolerances
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 configuration allows for the detection of maximum flexure stress by the detection elements, significantly increasing the sensitivity of the angular acceleration sensor.
Implementation Method 1
two piezoresistors 105A and 105B... detect stress generated in the beam
Data Source
AI summary
An angular acceleration sensor includes a stationary portion, a weight portion, a beam including a flat plate portion, one end portion of the flat plate portion in a lengthwise direction thereof being connected to the stationary portion and the other end portion thereof being connected to the weight portion, a central projection that projects in a thickness direction of the flat plate portion, and that is disposed at a center of the flat plate portion in a widthwise direction thereof, and end-side projections that are disposed at opposite ends of the flat plate portion in the widthwise direction, respectively, and that project in the thickness direction of the flat plate portion, and detection elements that are disposed on the flat plate portion at positions different from a center of the flat plate portion in the lengthwise direction, and that detect stress generated in the beam.