Accelerometer Gimbal Thickness and Flexible Arm Design

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Solution Overview

Problem

Conventional piezoelectric accelerometers with a single proof mass and arm are prone to breakage due to resonance, while those with multiple proof masses and arms have high impact resistance but low sensitivity.

Innovation Solution

An acceleration sensing structure featuring a frame, proof mass, gimbal, and symmetrically arranged inner and outer flexible arms, where the gimbal thickness is at least half and no more than equal to the proof mass thickness, allowing for deformation and improved sensitivity and structural stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single proof mass and single arm structure is used, then sensitivity is high, but the structure is easily breakable by resonance

Engineering Contradiction:

ImprovesensitivityVSAvoidstructure reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The proof mass is divided into multiple segments (first proof mass and second proof mass) connected by flexible arms, transforming a single rigid structure into a segmented flexible structure that can absorb resonance energy while maintaining sensitivity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The structure transitions from rigid components to flexible arms that can dynamically adapt to resonance conditions, allowing the structure to flex and absorb energy rather than break under resonant stress

Inventive Principle:

Principle #15Dynamics

2Strength

If multiple proof masses and multiple arms are used, then impact resistance is improved, but sensitivity becomes low

Engineering Contradiction:

Improveimpact resistanceVSAvoidsensitivity

Core Design Contradiction:

StrengthVSMeasurement precision

Solution Approach 1:

Different regions of the structure have different flexibility characteristics - the flexible arms provide local flexibility for impact absorption while the proof mass segments maintain local rigidity for sensitivity, creating localized functional zones within the overall structure

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The structure combines rigid proof mass segments with flexible arms to create a composite mechanical system that exhibits both high impact resistance from the flexible components and high sensitivity from the rigid sensing elements

Inventive Principle:

Principle #40Composite materials

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 proposed structure enhances sensitivity and structural reliability, achieving higher performance and frequency response compared to existing designs, as demonstrated by simulation results showing improved sensitivity and frequency of merit.

Implementation Method 1

the at least two outer flexible arms are deformed when the proof mass moves

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS11287440B2Acceleration sensing structure and accelerometer

Publication Date: 2022.03.29 NATIONAL TSING HUA UNIVERSITY

AI summary

An acceleration sensing structure includes a frame, a proof mass, a gimbal and at least two outer flexible arms. The proof mass is suspended from the frame and has a first thickness. The proof mass is surrounded by and connected to the gimbal. The gimbal has a second thickness. The at least two outer flexible arms are connected between the gimbal and the frame, and the at least two outer flexible arms are arranged symmetrically. The second thickness is larger than or equal to one-half of the first thickness and is smaller than or equal to the first thickness, and when the proof mass moves, the at least two outer flexible arms are deformed.