Magnetic Linear Position Sensor With Symmetric Magnet Array
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Solution Overview
Problem
Existing magnetic linear position sensors in motor vehicles face interference issues due to the magnetic fields of fork and clutch position sensors, leading to inefficiencies and redesign challenges, necessitating a solution that minimizes magnetic mass and interference.
Innovation Solution
A magnetic linear position sensor design featuring an array of magnets with varying sizes and positions along a line, optimized using simulation and optimization algorithms to minimize magnetic mass and interference, while maintaining high linearity and sensing distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the size of magnets for clutch position sensor is increased, then the sensing capability is improved, but the magnetic interference to fork position sensor increases and packaging becomes more difficult
Solution Approach 1:
The magnetic sensor system is divided into two independent sensor modules: a clutch position sensor and a fork position sensor. Each sensor has its own magnet array and sensing elements, allowing them to operate independently with minimized mutual interference while maintaining individual sensing capabilities
Solution Approach 2:
A magnetic shield is introduced as an intermediary component between the clutch position sensor and fork position sensor. This shield blocks and redirects magnetic field lines, preventing the magnetic field from the clutch sensor magnets from interfering with the fork sensor while allowing the fork sensor magnets to effectively sense clutch fork position
2Object-affected harmful factors
If shields are added to reduce magnetic interference, then magnetic interference is reduced, but device complexity and packaging difficulty increase
Solution Approach 1:
The magnetic shield is integrated into the sensor housing structure rather than being a separate component. The shield serves dual purposes: reducing magnetic interference between sensors and providing structural support for the sensor assembly, thereby simplifying packaging and reducing overall device complexity
Solution Approach 2:
The sensor housing is designed to perform multiple functions: it provides mechanical protection for the sensing elements, structures the magnet array positioning, and incorporates magnetic shielding properties. This multi-functionality eliminates the need for separate shielding components and simplifies the overall packaging
3Object-affected harmful factors
If distance between fork magnet and clutch position sensor magnet is increased, then magnetic interference is reduced, but sensing distance and linearity performance deteriorate
Solution Approach 1:
The magnet array uses non-uniform spacing where magnets closer to the center have larger gaps and magnets at the edges have smaller gaps. This local variation in spacing optimizes the magnetic field distribution to maintain linear sensing response across the entire range of motion while keeping the overall sensor compact
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 optimized sensor design achieves minimal magnetic interference, high linearity, and extended sensing distance with reduced magnetic mass, addressing the interference and redesign issues of existing sensors.
Implementation Method 1
The array of magnets is distributed along a line to form a magnetic field relay along the line
Implementation Method 2
The magnetic field sensor moves back and forth over the array of magnets to sense the magnetic field of the array of magnets
Data Source
AI summary
A magnetic linear position sensor includes an array of N number of magnets. The array of magnets is distributed along a line to form a magnetic field relay along the line. The sizes and positions of the magnets in the array of magnets are symmetric along the line, and the size of the magnets decreases from the sides of the array of magnets towards the center of the array of magnets. The magnetic linear position sensor further includes a magnetic field sensor spaced apart and positioned above the array of magnets. The magnetic field sensor moves back and forth over the array of magnets to sense the magnetic field of the array of magnets.