Electromagnetic Quasi-Zero Stiffness Displacement Sensor
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Solution Overview
Problem
Current methods for measuring vibration, such as using acceleration sensors and displacement sensors, suffer from cumulative errors, system delays, high costs, and operational limitations in dusty or watery environments, and mechanical contact quasi-zero stiffness systems face contact fatigue issues.
Innovation Solution
An electromagnetic type quasi-zero stiffness absolute displacement sensor is developed, featuring an intermediate shaft, force sensor, electromagnetic negative stiffness unit, and mechanical positive stiffness unit, which uses non-contact electromagnetic forces and a spiral spring to measure vibration with high accuracy and avoid contact fatigue, comprising a ring permanent magnet, electromagnetic coils, and sliding bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acceleration sensor integration method is used, then displacement measurement is achieved, but cumulative error increases and system delay increases
Solution Approach 1:
The patent replaces the acceleration sensor integration method with a direct displacement sensing mechanism using electromagnetic force and spring deflection. The intermediate shaft connects the measured object to a spring, and electromagnetic force balances the spring's restoring force to directly indicate displacement without integration, eliminating cumulative error and reducing system delay.
2Measurement precision
If laser Doppler sensor or laser radar is used, then displacement measurement is achieved, but cost increases and operating condition requirements increase
Solution Approach 1:
The patent uses conventional, inexpensive components such as electromagnetic coils, permanent magnets, and mechanical springs to create a displacement sensor that is far cheaper than laser-based systems. These components have no special operating requirements and can function in harsh environments including dust and water, eliminating the need for protected enclosures or controlled conditions.
3Measurement precision
If mechanical contact quasi-zero stiffness system is used, then displacement measurement is achieved, but contact fatigue occurs and service life decreases
Solution Approach 1:
The patent replaces mechanical contact elements with non-contact electromagnetic force to achieve quasi-zero stiffness. The electromagnetic coil generates force that balances the spring's restoring force without physical contact, eliminating wear and contact fatigue while maintaining measurement accuracy, thereby significantly extending service life and improving reliability.
4Ease of manufacture
If simple structure and low cost are achieved, then manufacturing ease improves, but measurement accuracy may deteriorate
Solution Approach 1:
The patent uses parameter changes in the electromagnetic system to achieve high measurement accuracy with simple structure. By adjusting electromagnetic force parameters (current, coil turns, magnet strength) to balance the spring's restoring force, the system achieves precise displacement measurement using off-the-shelf components, maintaining both simplicity and accuracy.
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 sensor achieves high measurement accuracy, simple structure, low costs, and extended service life by utilizing non-contact electromagnetic forces and a mechanical positive stiffness unit to measure elastic restoring forces, effectively overcoming the limitations of existing technologies.
Implementation Method 1
an electromagnetic coil fastened onto an inner wall of the upper housing... a magnetic field generated by the electromagnetic coil interacts with a magnet field generated by the ring permanent magnet to generate electromagnetic force
Implementation Method 2
a mechanical positive stiffness unit comprises a lower housing, a lower end cover, a spiral spring, and a spring support... the spring support is connected to a lower end of the spiral spring
Data Source
AI summary
An electromagnetic type quasi-zero stiffness absolute displacement sensor that includes an intermediate shaft, upper end cover, first sliding bearing arranged on the upper end cover, upper housing fixedly connected to the upper end cover, electromagnetic coil fastened onto an inner wall of the upper housing, spiral spring, spring support connected to a lower end of the spiral spring, force sensor fastened onto a lower end surface of the spring support, lower end cover fastened onto lower end surface of the force sensor, and a lower housing connected to the lower end cover; the intermediate shaft sequentially passes through, from top down, the first sliding bearing, upper end cover, and electromagnetic coil, and is connected to an upper end of the spiral spring; and the upper housing is provided therein with a ring permanent magnet that is nested on the intermediate shaft and is not in contact with the electromagnetic coil.