Magnetic Impulse Ring Magnetization for Low Pitch Deviation

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Solution Overview

Problem

Conventional magnetic impulse rings used in rotary electrical machines suffer from manufacturing and magnetization constraints, leading to geometrical and magnetic inconsistencies between North and South poles, resulting in measurement and control errors.

Innovation Solution

A magnetic impulse ring with a central axis, featuring a target holder and target with alternating South and North magnetic poles, where the target is made from magnetizable materials like anilco or ferrite powder embedded in resin or plastic, and the holder is made from ferromagnetic materials, with improved magnetization techniques to reduce Total Pitch Deviation to ≤0.5%, and integrated into a bearing unit and rotary electrical machine for precise angular position tracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional manufacturing and magnetization methods are used for magnetic impulse rings, then production is simpler and faster, but the Total Pitch Deviation exceeds 0.5% causing measurement and control errors

Engineering Contradiction:

ImproveTotal Pitch DeviationVSAvoidmanufacturing constraints

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by performing precise centering of the target ring on the magnetization axis before magnetization, and by pre-positioning the target ring with high circularity on the central axis. These preliminary positioning actions ensure that subsequent magnetization produces poles with minimal pitch deviation, achieving ≤0.5% TPD while maintaining manufacturing feasibility.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes critical parameters including the circularity of the target ring outer diameter (improved to ≤0.05mm through machining), the centering precision on the magnetization axis, and the magnetic pole spacing. By controlling these parameters during manufacturing, the Total Pitch Deviation is reduced to ≤0.5% while keeping the manufacturing process practical.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If conventional magnetic impulse rings are used in rotary electrical machines, then the structure is simpler, but angular position tracking accuracy deteriorates due to pole inconsistencies

Engineering Contradiction:

Improveangular position tracking accuracyVSAvoidmagnetization techniques

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces conventional less precise magnetization methods with a controlled magnetization process that uses a magnetization yoke and precise positioning mechanism. This substitution of the magnetization system with a more controlled mechanical and magnetic field system enables achievement of ≤0.5% Total Pitch Deviation, directly improving angular position tracking accuracy through magnetic detection means.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If target ring outer diameter circularity is improved through machining, then Total Pitch Deviation is reduced, but manufacturing time and cost increase

Engineering Contradiction:

Improveouter diameter circularityVSAvoidmanufacturing cycle time

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies partial action by performing machining only on the outer diameter of the target ring to improve circularity to ≤0.05mm, rather than machining all surfaces. This selective machining approach achieves the necessary precision for low Total Pitch Deviation while minimizing additional manufacturing time and cost compared to complete machining.

Inventive Principle:

Principle #16Partial or excessive action

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 solution significantly reduces angular position errors of the rotor, enhances machine performance, and when used in hybrid traction systems, reduces CO2 emissions by minimizing electrical oscillations and extending battery life.

Implementation Method 1

Magnetizing the target ring thanks to a magnetization device so as to form a plurality of magnetic poles pairs formed in the target

Methodology Applied

Scientific EffectMagnetization: Magnetism

Implementation Method 2

The detections means comprise a Hall effect cell or a Magneto-resistive cell

Methodology Applied

Scientific EffectHall effect: Hall Effect

Implementation Method 3

The detections means comprise a Hall effect cell or a Magneto-resistive cell

Methodology Applied

Scientific EffectMagneto-resistive effect: Magnetoresistance

Data Source

PatentUS20230383787A1Magnetic impulse ring, bearing unit and rotary electrical machine comprising a magnetic impulse ring, and method to obtain a magnetic impulse ring

Publication Date: 2023.11.30 AB SKF SKF PATENT DEPARTMENT

AI summary

A magnetic impulse ring having a central axis that includes a target holder and a target that is fixed to the target holder. The target provides a plurality of alternating South and North magnetic poles. The target is adapted to cooperate with magnetic detection means for tracking the rotation of the magnetic impulse ring around its central axis. The Total Pitch Deviation (TPD) of the magnetic impulse ring is less than or equal to 0.5%.