Ball Bearing Retainer Pocket Structure for Lower Oil Shear Torque
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Solution Overview
Problem
Existing ball bearings struggle to achieve significant torque reduction while maintaining bearing functionality and cost-effectiveness, as previous designs often result in excessive contact pressure, shorter life, or increased costs due to shape changes.
Innovation Solution
A retainer design with specific dimensional relationships between the pocket circumferential length, ball diameter, and gap, along with a recess depth and offset, is implemented to maximize torque reduction while ensuring the retainer's manufacturability and preventing deformation during press working, featuring a ball non-contact portion and a rounded recess edge to avoid boundary contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the contact area between the guide surface of the pocket and the ball is reduced to lower oil shear torque, then torque is reduced, but excessive contact pressure and shorter bearing life occur
Solution Approach 1:
The invention applies local quality by creating a ball non-contact portion at the center of the ball facing surface, while maintaining contact capability at the peripheral regions. This localized modification reduces oil shear torque in the center area while preserving adequate contact area at the periphery to distribute load and prevent excessive contact pressure, thus resolving the contradiction between torque reduction and bearing life maintenance.
Solution Approach 2:
The invention changes the geometric parameters of the pocket by defining specific dimensional relationships: the ball non-contact portion has a circumferential length A where 0.70≤A/(B+C)≤0.90, and an axial length D where 0.25≤D/E≤0.40. These parameter changes optimize the balance between reducing contact area for torque reduction and maintaining sufficient contact area for load distribution, preventing excessive contact pressure while reducing oil shear torque.
2Loss of energy
If internal design specifications are changed to reduce torque, then torque is reduced, but bearing life decreases and functions are affected
Solution Approach 1:
The invention modifies only the local region of the pocket by creating a ball non-contact portion at the center, while maintaining the overall pocket structure and peripheral contact areas. This localized modification reduces torque through decreased oil shear resistance without significantly altering the load-bearing capacity, thus preserving bearing life and functionality while achieving torque reduction.
Solution Approach 2:
The invention applies partial action by creating a ball non-contact portion that occupies only a portion of the pocket's ball facing surface (with circumferential length ratio 0.70≤A/(B+C)≤0.90). This partial modification is sufficient to reduce torque through decreased oil shear torque (which accounts for 71% of total torque) while maintaining adequate contact area to preserve bearing life and functionality.
3Loss of energy
If the shape of the retainer is significantly changed to reduce torque, then torque is reduced, but manufacturing cost increases due to new mold requirements
Solution Approach 1:
The invention achieves torque reduction primarily through parameter changes (defining specific dimensional relationships for the ball non-contact portion) rather than fundamental shape changes. The pocket structure and overall retainer geometry remain substantially the same, allowing utilization of existing molds with minimal modifications, thus reducing manufacturing cost while achieving torque reduction through optimized dimensional parameters.
4Manufacturing precision
If the retainer is press worked to achieve precise dimensional relationships, then manufacturing precision is improved, but deformation may occur during press working
Solution Approach 1:
The invention applies preliminary action by designing the pocket structure with predetermined dimensional relationships that account for press working effects. The ball non-contact portion dimensions (A, D, E, F) are designed with specific ratios that ensure the desired final dimensions are achieved after press working, compensating for potential deformation during the forming process and ensuring manufacturing precision while maintaining structural stability.
Data Source
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AI summary
Provided are a retainer capable of imparting a torque reduction effect even at low cost and a ball bearing (deep-groove ball bearing) having the retainer assembled thereto. The retainer includes two annular retaining plates (27A, 28B) combined with each other, the two annular retaining plates each having semispherical bulging portions (26) arranged at predetermined intervals along a circumferential direction of the retainer, the semispherical bulging portions (26, 26) of the two annular retaining plates, which face each other, forming a pocket (30) having a ring-like shape, for retaining a ball (16). The pocket (30) includes a ball non-contact portion (32) formed in a ball facing surface of the pocket (30) at a center portion in a pocket axial direction, the ball non-contact portion (32) being defined by a recess (34) extending in a pocket circumferential direction. The following relationship is set: A/(B+C)=0.70 to 0.90, where "A" represents a pocket circumferential length of the ball non-contact portion (32), "B" represents a diameter of the ball, and "C" represents a gap formed between the ball (16) and the ball facing surface of the pocket (30).