Bearing Cage Concave Pockets Grease Leakage
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Solution Overview
Problem
Existing ball bearing assemblies face challenges with grease leakage due to temperature changes, which lead to increased torque and reduced lifetime, especially when using resinous or iron plate blanked cages, as grease deposits on the inner ring seal groove and causes friction-induced wear.
Innovation Solution
A ring-shaped cage with concaved pockets that prevent grease deposition on the inner shoulder, featuring a concaved portion on the inner diametric side, which reduces grease accumulation and eliminates the need for additional sealing features, combined with a press-molded manufacturing process for high strength and low cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tensioning force for urging the sealing lip segment against the seal groove is strengthened to prevent breathing, then the prevention of grease leakage is improved, but the torque increases
Solution Approach 1:
The invention extracts the harmful function of the cage pocket (which was scraping grease and depositing it on the seal groove) by removing the protruding portion that caused the scraping action. This eliminates the source of grease contamination on the seal groove without affecting the sealing lip's ability to prevent breathing.
Solution Approach 2:
The invention converts the harmful scraping action into a beneficial smooth surface that prevents grease accumulation. By modifying the pocket shape to have a concaved portion, the cage surface becomes grease-resistant and prevents the deposition that led to seal groove contamination and increased torque.
2Reliability
If a ventilating cutout is provided in the sealing lip segment to prevent breathing, then the resistance to grease leakage is improved, but grease deposits on the cutout causing leakage to occur
Solution Approach 1:
The invention removes the ventilating cutout feature entirely and instead addresses the root cause of grease leakage by modifying the cage pocket shape. This eliminates the surface where grease could deposit and cause leakage.
3Reliability
If the cage pocket inner surface is made smooth to prevent grease deposition, then grease leakage is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The invention applies curvature to the cage pocket inner surface by creating a concaved portion with a predetermined radius of curvature. This curved surface naturally prevents grease deposition through its geometry rather than requiring high-precision smooth finishing, thus maintaining manufacturing feasibility while achieving grease leakage prevention.
4Force
If the cage is made of resinous material to reduce friction, then torque is reduced, but strength and resistance to high speed decrease
Solution Approach 1:
The invention applies local quality modification by creating a specific concaved portion shape in the cage pocket inner surface that is optimized for grease prevention. This localized geometric feature provides the necessary grease-resistant properties without requiring the entire cage to be made of specialized materials, thus maintaining overall cage strength while preventing grease deposition.
Data Source
AI summary
A cage for a ball bearing assembly has a pocket for accommodating one of the balls defined at a plurality of locations in a direction circumferentially thereof and each of the pockets has an inner surface so shaped as to represent a concaved spherical surface. A concaved portion extending from an open edge on the cage inner diametric side towards the cage outer diametric side is provided in an inner surface of each of the pockets. The sectional shape of the inner surface of this concaved portion in a cage circumferential direction is represented by an arcuate shape of a radius of curvature smaller than the radius of curvature of the concaved spherical surface defining the inner surface of the respective pocket. The inner surface of each of the pockets may be formed with a film.