Integrated Sensing Magnet Pole Design for EPS
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Solution Overview
Problem
The existing electronic power steering (EPS) systems require complex magnetization processes and additional materials, leading to increased costs and potential interference that can degrade sensing accuracy due to the presence of a dummy track and dual magnetization processes in the sensing magnet structure.
Innovation Solution
A sensing magnet design where some poles serving as sub magnets extend to function as main magnets, eliminating the need for a separate main magnet and dummy track, thereby simplifying the magnetization process and reducing material costs, while maintaining or improving sensing accuracy by using hall IC sensors to detect changes in magnetic flux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a dummy track is disposed between the main magnet and the sub magnet to minimize magnetic flux interference, then magnetic flux interference is reduced, but device complexity and material costs increase
Solution Approach 1:
The invention extracts and removes the dummy track from the sensing magnet structure. By eliminating this non-functional component, the patent reduces device complexity and material costs while maintaining the magnetic flux isolation function through alternative means (proper pole arrangement and spacing).
Solution Approach 2:
The invention merges the main magnet and sub magnet into a single integrated sensing magnet structure without requiring a separating dummy track. The magnets are directly adjacent to each other, with the interface between them serving as the magnetic flux isolation boundary, thereby simplifying the overall structure.
2Manufacturing precision
If dual magnetization processes are performed at predetermined intervals for the main magnet and sub magnet, then sequential magnetization is achieved, but manufacturing time increases
Solution Approach 1:
The invention combines the magnetization processes into a single unified operation. By designing the sensing magnet with an odd number of poles where adjacent poles have opposite polarities, both the main magnet and sub magnet regions are magnetized simultaneously in one process, eliminating the need for separate sequential magnetization steps.
3Measurement precision
If the sub magnet includes a larger number of poles than the main magnet to finely divide rotation angle measurement, then measurement precision is improved, but magnetic flux interference between magnets increases
Solution Approach 1:
The invention applies different pole configurations to different regions: the main magnet has poles arranged to match the motor rotor poles for basic rotation detection, while the sub magnet has additional poles for finer angle division. The interface between magnets creates a magnetic flux isolation zone that prevents interference while allowing each region to fulfill its specific measurement function.
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 design simplifies the magnetization process, reduces material costs, and enhances sensing accuracy by eliminating interference and the need for dual magnetization, while maintaining precise rotation angle measurement capabilities.
Implementation Method 1
The sensor detects a change in magnetic flux in accordance with rotation of the main magnet
Implementation Method 2
using hall IC sensors to detect changes in magnetic flux
Data Source
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AI summary
Provided are a motor and a sensing magnet of the motor. The sensing magnet includes a through hole that is positioned at a center portion thereof, and a plurality of poles which are formed along an outer periphery thereof. Here, the plurality of poles include a first pole and a second pole extending from the first pole in a direction of the through hole.