Electric Machine Anti-Rotation Device for Bearing Creep Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Bearing creep in electric machines, particularly with vertical shafts, leads to noise and premature failure due to relative motion between the bearing outer ring and the housing, as existing solutions either eliminate all motion or are ineffective in accommodating temperature changes and material tolerances.
Innovation Solution
An anti-rotation device with a first feature engaging the bearing outer ring and a second feature engaging the housing, limiting the rotation of the outer ring within the bearing seat, while allowing axial movement to accommodate thermal and material-related changes, thus preventing creep.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an interference fit or adhesive is used between the bearing outer ring and housing to eliminate relative motion, then bearing creep is prevented, but axial movement accommodation is lost and bearing preload increases
Solution Approach 1:
The solution segments the constraints by introducing a separate anti-rotation device that only prevents rotational movement while leaving axial movement freedom. The anti-rotation device consists of a keyway in the bearing outer ring mating with a corresponding key in the housing, creating a specialized constraint that addresses only the creep problem without eliminating all relative motion.
Solution Approach 2:
The anti-rotation device acts as an intermediary element between the bearing outer ring and housing. This intermediate component selectively transmits constraints - preventing rotation through the keyway-key interface while allowing axial expansion and contraction to occur naturally.
2Reliability
If all relative motion is eliminated between bearing and housing, then bearing creep is prevented, but bearing life is reduced due to excessive preload
Solution Approach 1:
The constraint is segmented into rotational and axial components. The anti-rotation device segments the motion control by specifically targeting rotational movement prevention while leaving axial movement unrestricted, thereby preventing creep without imposing excessive preload that would reduce bearing life.
Solution Approach 2:
Instead of preventing all motion as the conventional approach does, the invention inverts the strategy by allowing all motion except rotation. This selective permission approach prevents creep (which is caused by rotation) while maintaining the natural axial movement that preserves bearing life.
3Adaptability or versatility
If o-rings or polymer rings are placed between bearing and housing to accommodate motion, then axial movement is allowed, but they are ineffective or not sufficiently durable to prevent creep
Solution Approach 1:
The invention replaces the flexible polymer-based solution (o-rings, polymer rings) with a rigid mechanical constraint system. The keyway-key anti-rotation mechanism provides precise rotational constraint through direct mechanical contact, offering superior durability and effectiveness compared to deformable polymer elements.
Solution Approach 2:
The solution combines different material properties by using metal-to-metal contact for the anti-rotation constraint (keyway and key) while allowing the bearing and housing materials to naturally handle thermal expansion. This composite approach of rigid constraint with flexible thermal accommodation provides both creep prevention and durability.
Data Source
AI summary
A bearing assembly cooperates with a bearing seat formed in a bearing housing. The assembly includes a bearing having an inner ring, an outer ring and a rolling element in engagement with the inner ring and the outer ring, and an anti-rotation device. The anti-rotation device engages the outer ring of the bearing and with the bearing housing to limit the rotation of the outer ring of the bearing within the bearing seat formed in the bearing housing. The anti-rotation device includes a first feature for engagement with the outer ring of the bearing and a second feature for engagement with the bearing housing. The first feature and the second feature limit the rotation of the outer ring of the bearing within the bearing seat formed in the bearing housing.