Angular Velocity Sensor Element Stress Dispersion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing angular velocity sensors face challenges in achieving high sensitivity and reduced size while maintaining structural integrity, particularly in the design of the support and connection portions which can be prone to stress and breakage under thermal expansion differences and mechanical shocks.
Innovation Solution
The sensor element incorporates a piezoelectric body with a unique configuration of driving and detecting arms, a broadened connection portion for the holding part, and a specific arrangement of excitation and detecting electrodes, which enhances sensitivity and reduces size while improving structural strength by dispersing stress and preventing breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the support rod is made narrower to reduce size, then the sensor element size is reduced, but the structural strength and resistance to mechanical shocks deteriorate
Solution Approach 1:
The support rod is designed with varying cross-sectional dimensions along its length. Specifically, the connection portion has a larger cross-sectional area than the intermediate portion, creating local strength variations that optimize both size and structural integrity. This non-uniform geometry allows the support rod to resist mechanical shocks and thermal expansion forces while maintaining a compact overall size.
2Strength
If the connection portion is broadened to improve structural strength, then resistance to thermal expansion and mechanical shocks improves, but the sensor element size increases
Solution Approach 1:
The support rod is divided into distinct functional segments: a connection portion with larger cross-section for strength, and intermediate portions with smaller cross-sections for size reduction. This segmentation allows each portion to be optimized for its specific function - the connection portion handles stress concentration while the narrower portions minimize overall volume.
Solution Approach 2:
The broadened connection portion is strategically positioned only where needed - at the base part connection point where thermal expansion and mechanical shock stresses are most concentrated. This localized strengthening provides maximum structural benefit with minimal impact on overall sensor element size.
3Manufacturing precision
If chamfering is applied to reduce etching residue influence, then manufacturing precision improves, but the structural strength at corner portions may deteriorate
Solution Approach 1:
Chamfering is applied selectively only to specific corner portions where etching residues are most problematic, rather than uniformly to all corners. The chamfered surfaces are positioned to facilitate residue removal while the overall corner geometry maintains sufficient strength through the broader connection portion design.
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 enhances the sensitivity and accuracy of angular velocity detection while reducing the size and vulnerability to mechanical shocks, achieving both improved performance and robustness.
Implementation Method 1
A piezoelectric body of the sensor element of Patent Literature 1 has a base part, a pair of driving arms extending alongside each other from the base part, and a pair of detecting arms extending from the base part to the side opposite to the pair of driving arms. When the sensor element rotates in a state where the driving arms are excited, a Coriolis force is generated and the detecting arms vibrate with amplitudes corresponding to the angular velocity. Due to this, an electrical signal corresponding to the angular velocity is generated in the detecting arms.
Implementation Method 2
When the sensor element rotates in a state where the driving arms are excited, a Coriolis force is generated and the detecting arms vibrate with amplitudes corresponding to the angular velocity.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
In a piezoelectric body of a sensor element, two first arms extend alongside each other from a base part to a +y side. Two second arms extend alongside each other from the base part to a -y side. A holding part extends between the two second arms from the base part to the -y side and extends out beyond front ends of the two second arms to the -y side. A mounting part on which a plurality of element terminals are located is connected to an end part on the -y side. The holding part includes a main portion and a connection portion. Where the length in an x-direction is the width, the main portion extends from a position between the front ends of the two second arms to a side where the base part is located, while maintaining a width not less than a width of a portion located between the front ends of the two second arms. The connection portion which is connected to the main portion and the base part and is broader in width than the main portion.