Physical Quantity Sensor Coupling Portion Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing physical quantity sensors face issues with excessive acceleration causing bending stress and potential breakage due to short coupling portions, leading to reliability concerns.
Innovation Solution
The design includes a coupling portion extended 1.4 times the length from the rotation shaft to the mass portion, with protrusions and slits to reduce bending stress and improve impact resistance, while maintaining sensitivity through electrostatic capacitance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the coupling portion is made short to reduce device complexity, then the structure is simpler, but the bending stress increases and breakage risk increases
Solution Approach 1:
The patent changes the parameter of coupling portion length from short to extended (1.4 times the length from rotation shaft to mass portion). This parameter change reduces bending stress by 0.6 times according to the patent, thereby reducing breakage risk while maintaining structural simplicity through the extended design
2Reliability
If the coupling portion is extended to reduce bending stress, then impact resistance improves, but device complexity increases
Solution Approach 1:
The patent extends the coupling portion length to 1.4 times the length from rotation shaft to mass portion. This parameter change reduces bending stress by 0.6 times, improving impact resistance and reliability. The extended structure is implemented through a protrusion that extends in the intersecting direction, providing a clear geometric definition that manages structural complexity
3Volume of moving object
If the mass portion is positioned close to the rotation shaft to reduce device size, then the overall dimension is smaller, but the coupling portion length is reduced increasing bending stress
Solution Approach 1:
The patent introduces a protrusion that extends in the intersecting direction (perpendicular to the rotation shaft axis). This dimensional extension allows the mass portion to be positioned close to the rotation shaft for compactness while the protrusion provides the necessary coupling length in a different dimension to reduce bending stress
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 reduces bending stress by 0.6 times, suppresses breakage, and enhances the sensor's impact resistance and reliability, while improving sensitivity and accuracy in measuring acceleration.
Implementation Method 1
measures the acceleration from an electrostatic capacitance that changes according to the acceleration applied in a vertical direction
Data Source
AI summary
A physical quantity sensor includes: a movable body that includes a beam portion as a rotation shaft, a coupling portion that is connected with the beam portion and is provided in a direction intersecting with the beam portion, and a first and a second mass portions as a mass portion that are connected with the coupling portion; a first and a second fixed electrodes as a measurement electrode that are provided on a support substrate and are opposed to the first and the second mass portions; and a protrusion that is provided in a region where the first and the second fixed electrodes are provided and protrudes from the support substrate toward the first and the second mass portions, in which a length of the coupling portion in the intersecting direction is 1.4 or more times a length from the beam portion to the first and the second mass portions.