Linear Actuator Sensor Magnet Shape for Precise Position Detection
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Solution Overview
Problem
Existing linear actuators face challenges in accurately detecting the position of a magnet due to decreased magnetic flux density near the magnetic pole boundary, which can lead to inaccurate positioning of the drive assembly.
Innovation Solution
The actuator device incorporates a sensor magnet fixed to the drive assembly, extending in the magnetization direction, and a magnetic sensor opposing the sensor magnet to detect its magnetic flux. The sensor magnet's width at its barycenter is wider than its ends, enhancing magnetic flux density detection near the magnetic pole boundary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor magnet is made larger to improve magnetic flux density detection, then the detection precision is improved, but the device size and cost increase
Solution Approach 1:
The sensor magnet employs non-uniform thickness distribution, being thicker at the center and thinner at the ends. This local quality variation creates stronger magnetic flux density at the magnetic pole boundaries without increasing the overall magnet volume, thereby improving detection precision while maintaining compact size
Solution Approach 2:
The invention changes the geometric parameter of the sensor magnet by varying its thickness profile. By making the magnet thicker at the center region and thinner at the end regions, the magnetic flux density distribution is optimized to ensure detectable signal strength at pole boundaries without requiring a larger overall magnet dimensions
2Reliability
If the sensor magnet width at ends is increased to improve magnetic flux density, then the detection reliability is improved, but the device complexity increases
Solution Approach 1:
Rather than uniformly increasing the magnet width throughout, the invention applies local quality enhancement by selectively increasing the thickness only at the center region while keeping the end regions thinner. This targeted approach improves magnetic flux density at critical detection points without adding unnecessary structural complexity
Solution Approach 2:
The invention addresses the detection reliability issue by modifying the magnet structure in the thickness dimension (third dimension) rather than only in the width dimension. By varying the thickness profile along the length of the magnet, the magnetic flux density is enhanced at pole boundaries without requiring increased width, thereby maintaining simpler device structure
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 allows for accurate detection of the magnetic flux density near the magnetic pole boundary, improving the precision of position detection for the drive assembly and reducing the need for increased sensor magnet size, thus maintaining cost-effectiveness.
Implementation Method 1
a magnetic sensor that opposes the sensor magnet in a second direction intersecting the first direction to detect a magnetic flux of the sensor magnet
Data Source
AI summary
An actuator device includes a drive assembly that is movable in a first direction, a sensor magnet that extends in the first direction that is a magnetization direction, the sensor magnet being fixed to the drive assembly, and a magnetic sensor that opposes the sensor magnet in a second direction intersecting the first direction to detect a magnetic flux of the sensor magnet. As viewed from the second direction, a width of the sensor magnet at a portion where a barycenter of the sensor magnet is positioned is wider than a width of two ends of the sensor magnet in the first direction.