Multi-Stage Piezoelectric Accelerometer High-G Sensitivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current piezoelectric accelerometers struggle to accurately measure a wide range of high linear and rotary accelerations, such as those experienced in munitions firing and object impacts, due to limitations in sensitivity and cross-sensitivity to rotational accelerations, and are prone to temperature sensitivity and potential damage from overloading.
Innovation Solution
The development of multi-stage piezoelectric-based accelerometers with staged piezoelectric elements and preloaded springs, which allow for increased sensitivity and measurement range by distributing force across multiple stages, minimizing cross-sensitivity and protecting against overloading through strategic stop mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single-stage piezoelectric accelerometer is used to measure high acceleration, then the measurement range can be extended, but the sensitivity and measurement precision deteriorate
Solution Approach 1:
The accelerometer is divided into multiple stages, each with its own piezoelectric element and seismic mass. The first stage handles low acceleration with high sensitivity, while the second stage handles high acceleration. This segmentation allows the system to achieve both high sensitivity and wide measurement range that a single stage cannot provide alone.
Solution Approach 2:
The patent introduces a second dimension of acceleration measurement by adding another piezoelectric element and seismic mass in series. This creates a multi-stage system where each stage operates in a different acceleration range, effectively adding a dimension to the measurement capability and allowing coverage of both low and high acceleration ranges simultaneously.
2Adaptability or versatility
If the piezoelectric element is subjected to high compression forces to measure high acceleration, then the measurement range increases, but the element is prone to damage from overloading
Solution Approach 1:
The acceleration measurement function is segmented across two stages. The first piezoelectric element handles low acceleration forces, while the second element handles high acceleration forces. This segmentation prevents any single element from being subjected to excessive forces that would cause damage, as each element only experiences forces within its safe operating range.
Solution Approach 2:
The first piezoelectric element and its associated seismic mass act as a cushioning stage for the second element. When high acceleration occurs, the first stage absorbs and limits the force transmission to the second element, preventing overloading and damage to the piezoelectric material before it can be damaged.
3Reliability
If preloading springs are added to protect the piezoelectric element, then reliability improves, but the device complexity increases
Solution Approach 1:
The protection function is segmented into the first stage's seismic mass and spring mechanism, which independently handles force limitation. This segmentation allows the protection mechanism to be integrated into the existing structure without requiring separate, complex protection systems, thereby limiting the increase in overall device complexity.
4Measurement precision
If multi-stage piezoelectric elements are used to increase sensitivity, then measurement precision improves, but the device complexity increases
Solution Approach 1:
The sensitivity function is segmented across two independent piezoelectric elements, each optimized for its specific acceleration range. The first element provides high sensitivity for low acceleration measurement, while the second element provides sensitivity for high acceleration measurement. This segmentation allows each element to be simpler and more specialized, rather than requiring one complex multi-functional element.
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
Enables precise measurement of high linear and rotary accelerations up to tens of thousands of Gs with reduced cross-sensitivity and enhanced durability, effectively addressing the limitations of existing designs.
Implementation Method 1
seismic mass(s) and piezoelectric element(s) are arranged such that when the accelerometer is subjected to acceleration, the resulting inertial forces introduce strain in the piezoelectric element(s), which in turn produce electrical outputs by virtue of the piezoelectric effect
Data Source
AI summary
An accelerometer including: a housing having an internal cavity; a piezoelectric material disposed in the internal cavity; a mass movable disposed in the internal cavity; and a spring disposed between the piezoelectric material and a portion of the housing, the spring being compressively preloaded against the piezoelectric material; wherein the mass is movable when the housing experiences an acceleration such that the mass acts upon the spring and the spring acts against the piezoelectric material, the piezoelectric material outputting a signal corresponding to a magnitude of the acceleration.