Tubular Magnet Holder Structure for Adjustable Press-Fit Load
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Solution Overview
Problem
Existing magnet holders for rotational angle sensing devices face difficulties in adjusting the press-fitting load due to constant wall thickness or reliance on shaft diameter for fixation, making it challenging to optimize the fit and prevent buckling.
Innovation Solution
A tubular magnet holder with distinct outer diameters and wall thicknesses for the magnet holding and press-fitting fixation portions, along with a connecting portion, allowing for independent design of the shaft diameter and press-fitting load adjustment, and featuring a tapered surface for improved strength and magnetic circuit compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a magnet holder with constant wall thickness is used, then the structure is simple, but the press-fitting load cannot be adjusted
Solution Approach 1:
The magnet holder employs different wall thicknesses in different regions: a first wall thickness in the magnet holding portion and a second wall thickness in the press-fitting fixation portion. This local differentiation allows the press-fitting fixation portion to be optimized for press-fitting load while the magnet holding portion maintains its function, thereby resolving the contradiction between structural simplicity and press-fitting load adjustability.
2Strength
If a magnet holder with large wall thickness is used, then the press-fitting fixation is strong, but the outer diameter becomes large
Solution Approach 1:
By concentrating the increased wall thickness specifically in the press-fitting fixation portion rather than uniformly across the entire magnet holder, the design achieves strong press-fitting fixation while minimizing the overall outer diameter. The magnet holding portion maintains a smaller, more compact dimension.
3Strength
If the wall thickness is increased for better press-fitting, then the fixation strength improves, but the magnetic circuit is affected
Solution Approach 1:
The increased wall thickness is localized to the press-fitting fixation portion, keeping the magnet holding portion's wall thickness optimized for magnetic circuit performance. This spatial separation ensures that the press-fitting strength is enhanced without compromising the magnetic flux path integrity.
Solution Approach 2:
The magnet holder features asymmetric wall thickness distribution, with the press-fitting fixation portion having a different wall thickness than the magnet holding portion. This asymmetry allows independent optimization of mechanical fixation strength and magnetic circuit characteristics.
4Ease of manufacture
If a uniform tubular structure is used, then the manufacturing is simple, but the fit optimization is limited
Solution Approach 1:
The magnet holder features different wall thicknesses in different portions (first wall thickness in magnet holding portion, second wall thickness in press-fitting fixation portion), which allows optimized fitting characteristics while maintaining manufacturability through standard fabrication processes.
Data Source
AI summary
A magnet holder is used in a rotational angle sensing device and is shaped in a tubular form while the magnet holder is configured to hold a magnet opposed to a magnetic sensor and is also configured to be securely press-fitted to a rotatable body. The magnet holder includes: a magnet holding portion that is located at one side of the magnet holder in an axial direction; a press-fitting fixation portion that is located at another side of the magnet holder in the axial direction; and a connecting portion that connects between the magnet holding portion and the press-fitting fixation portion. An outer diameter of the press-fitting fixation portion is different from an outer diameter of the magnet holding portion, and a wall thickness of the press-fitting fixation portion is different from a wall thickness of the magnet holding portion.