Bearing Cage Inner Surface Radius Variation for Grease Leakage Prevention
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Solution Overview
Problem
Ball bearing assemblies experience grease leakage due to the 'breathing' phenomenon caused by temperature changes, which existing solutions like increased urging force or vent cutouts fail to fully prevent without increasing torque or allowing air leakage.
Innovation Solution
A ring-shaped cage with a unique inner peripheral surface design where the radius to the inner surface area aligned with pockets is greater than the radius to the surface area between pockets, preventing grease adherence and leakage without increasing torque, using either a curved or polygonal shape that maintains structural strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the urging force of the sealing lips is increased to prevent grease leakage, then grease leakage is reduced, but torque increases
Solution Approach 1:
The cage's inner peripheral surface is designed with non-uniform radius - smaller radius at pocket-aligned areas and larger radius at intermediate areas - creating localized geometric variations that prevent grease accumulation at specific locations without requiring increased sealing force throughout the entire system
Solution Approach 2:
The cage geometry is designed in advance to prevent grease from adhering to the inner race sealing grooves and shoulder portions before the breathing phenomenon can cause leakage, eliminating the need for increased urging force on the sealing lips
2Reliability
If vent cutouts are formed in sealing lips to prevent grease adherence, then grease leakage is reduced, but air leakage occurs
Solution Approach 1:
The cage design creates localized geometric features at specific areas (pocket-aligned vs. intermediate areas) that selectively prevent grease accumulation where it would cause leakage, while maintaining the sealing system's integrity to prevent air leakage through vent cutouts
3Ease of manufacture
If the cage inner peripheral surface has uniform radius, then manufacturing is simple, but grease adheres to inner race sealing grooves causing leakage
Solution Approach 1:
The cage incorporates localized geometric variations in the inner peripheral surface radius - smaller at pocket-aligned areas and larger at intermediate areas - that prevent grease accumulation at critical locations while maintaining overall manufacturing feasibility through consistent formation methods
Solution Approach 2:
The radius parameter of the cage's inner peripheral surface is varied at different locations to change the grease flow and adhesion characteristics, preventing grease from adhering to the inner race sealing grooves and shoulder portions
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
Effectively prevents grease leakage from inner race sealing grooves and shoulder portions during rotation, reducing the likelihood of torque increase and maintaining structural integrity, as demonstrated by experimental results showing no grease leakage in assemblies with the new cage design compared to conventional designs.
Implementation Method 1
If the bearing temperature increases during this condition, the grease leakage may occur due to the breathing phenomenon. When the outer race rotates, the grease once adhering to the inner sealing grooves remains adhering thereto because no centrifugal force acts on the inner race.
Data Source
AI summary
A cage used in a ball bearing assembly is rendered to be of a ring shape having a plurality of pockets defined therein to hold a corresponding number of balls in a circumferential row. The radius of a bore of a circumferentially extending body of the cage as measured from the geometric center of the bore to an inner peripheral surface area of the circumferentially extending body aligned with each of the pockets is chosen to be greater than the radius as measured from the geometric center of the bore to a different inner peripheral surface area of the circumferentially extending body intermediate between the neighboring pockets.