Absolute Encoder Spacer Layout for Magnetic Flux Stability
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Solution Overview
Problem
Existing absolute encoders face detection accuracy issues due to magnetic flux disturbances caused by nearby magnetic materials, such as bearings, which affect the accurate detection of the rotation angle of the magnet.
Innovation Solution
Incorporating a spacer made of magnetic material between the sub-shaft gear and the bearing part, oriented to intersect the axial line, to mitigate magnetic flux interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a bearing made of magnetic material is used to support the sub-shaft gear, then strength and durability are improved, but magnetic flux distribution is disturbed causing deterioration in rotation angle detection accuracy
Solution Approach 1:
A non-magnetic material is introduced as an intermediary between the magnetic material bearing and the magnet. This intermediary prevents direct magnetic interaction between the bearing and magnet, eliminating the disturbance to magnetic flux distribution while maintaining the structural support function of the bearing. The non-magnetic material acts as a buffer that blocks magnetic field lines from being distorted by the magnetic bearing material.
Solution Approach 2:
The support structure is divided into multiple components: the magnetic material bearing for structural support, a non-magnetic material layer for magnetic field isolation, and the magnet for generating the magnetic field. This segmentation allows each component to perform its specific function without interfering with others, particularly preventing the magnetic bearing material from distorting the magnetic flux.
2Reliability
If a magnetic material member is disposed in the vicinity of the rotation axis, then structural requirements are met, but magnetic flux distribution is disturbed causing difference in magnetic flux change
Solution Approach 1:
A non-magnetic material is positioned between the magnetic material member and the magnet to serve as a magnetic field barrier. This intermediary prevents the magnetic material from creating unintended magnetic paths that would distort the flux distribution, thereby ensuring consistent magnetic flux change patterns for accurate rotation angle detection.
Solution Approach 2:
The patent applies different material properties to different regions: magnetic material is used where structural strength is needed, while non-magnetic material is specifically applied in regions where magnetic field integrity must be maintained. This localized material selection optimizes both structural reliability and measurement precision in different spatial zones.
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 suppresses deterioration in detection accuracy even when nearby components are made of magnetic materials, ensuring precise rotation angle detection.
Implementation Method 1
a magnetic flux of the magnet detected by the angle sensor periodically changes as the rotation axis rotates
Implementation Method 2
the member forms a magnetic path of the magnetic flux from the magnet
Data Source
AI summary
To suppress deterioration in the detection accuracy of a rotation angle of a magnet even when a member located in the vicinity of the magnet is made of a magnetic material. An absolute encoder includes a first sub-shaft gear configured to rotate based on rotation of a main shaft, a bearing part configured to rotatably support the first sub-shaft gear around an axial line A, a support shaft configured to support the bearing part, and a spacer provided between the first sub-shaft gear and the bearing part. At least a part of the spacer is formed of a magnetic material, and the spacer is formed extending in a direction intersecting the axial line A.