Bearing Assembly Encoder Protection Magnetic Field Intensity

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Solution Overview

Problem

Conventional bearing assemblies with magnetic encoders face challenges in generating a strong enough magnetic field for reliable rotation detection due to the presence of a non-ferromagnetic cover, and have limited flexibility in sensor placement.

Innovation Solution

A bearing assembly design that includes a magnetic encoder with a protective non-ferromagnetic cover allowing for a more intense magnetic field and flexible sensor positioning, eliminating the need for an inboard sealing device and optimizing the axial gap for reduced size and increased rigidity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a non-ferromagnetic protective cover is mounted on the outer bearing race to protect the encoder and seal the bearing, then the encoder is protected and the bearing is sealed, but the magnetic field intensity is reduced and sensor placement flexibility is limited

Engineering Contradiction:

Improveencoder protectionVSAvoidmagnetic field intensity

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The sealing function is extracted from the protective cover design and implemented through a separate sealing device arranged at the axially outer side of the bearing assembly. This allows the protective cover to be optimized for encoder protection without compromising magnetic field intensity, as the sealing function is handled independently.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If a non-ferromagnetic protective cover is mounted on the outer bearing race to protect the encoder and seal the bearing, then the encoder is protected and the bearing is sealed, but the sensor must be located exactly in front of the middle of the radial extension of the encoder at equal distance

Engineering Contradiction:

Improveencoder protectionVSAvoidsensor placement flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If an inboard sealing device is used to seal the bearing, then the bearing is sealed from the axially inner side, but the axial space is increased and rigidity is reduced

Engineering Contradiction:

Improvebearing sealingVSAvoidaxial dimension

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

Instead of sealing the bearing from the axially inner side (inboard), the sealing device is inverted to be arranged at the axially outer side (outboard) of the bearing assembly. This inversion allows sealing to be achieved while minimizing axial space requirements and maintaining assembly rigidity.

Inventive Principle:

Principle #13The other way round (Inversion)

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

Enhances magnetic field intensity, allows for flexible sensor placement, reduces manufacturing costs, and improves assembly compactness and rigidity by eliminating the inboard sealing device and minimizing axial dimensions.

Implementation Method 1

a magnetic encoder (23) mounted on a rotating bearing race and a sensor that is fitted on a stationary part at a location facing the encoder at a preset distance. Electric signals generated by the sensor due to the rotation of the encoder

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentUS8721186B2Bearing assembly with a protective cover for an encoder

Publication Date: 2014.05.13 AB SKF SKF PATENT DEPARTMENT

AI summary

A radially outer stationary bearing race (11) defines, on one if its sides, an inner cylindrical surface (29) and a radial side surface (32). A radially inner bearing race (15) has an outer cylindrical surface (26) facing the inner cylindrical surface (29). A magnetic encoder (23) in form of an annular disc is fixed onto the outer cylindrical surface (26) of the inner race (15) and is protected by a cover of non-ferromagnetic material (30) mounted on the outer race (11) and abutting against the radial side surface (32). The encoder (23)extends radially from the outer cylindrical surface (26) of the inner race (15) up to near the inner cylindrical surface (29) of the outer race (11). No sealing device is mounted in the gap between the cylindrical surfaces (29) and (26).