Ball Bearing Cage Guide Outer Raceway Torque
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Solution Overview
Problem
Conventional ball bearings face challenges in reducing torque due to high shear resistance of grease, which is exacerbated by a cage structure guided by balls, leading to increased rotational resistance and cost through additional grinding requirements.
Innovation Solution
A ball bearing design where the cage is positioned by guide portions contacting the outer raceway groove at non-contact areas, reducing shear resistance and eliminating the need for additional grinding on the outer ring, thereby decreasing torque and maintaining the bearing's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the cage is guided by the balls with small clearance, then the cage positioning is improved, but the shear resistance of grease increases
Solution Approach 1:
The guide portion acts as an intermediary element that contacts the outer ring's inner peripheral surface instead of the balls. This mediator transfers the cage positioning function from the balls to the outer ring, eliminating the need for small clearance between balls and cage, thereby reducing grease shear resistance while maintaining cage positioning accuracy.
2Force
If the cage is guided by the outer ring's shoulder portion, then the shear resistance of grease is reduced, but additional grinding is required on the outer ring
Solution Approach 1:
The guide portion is designed to contact the existing outer raceway groove surface, allowing the outer ring to serve multiple functions: supporting the balls through the raceway groove and guiding the cage through the guide portion contact. This multi-functionality eliminates the need for additional shoulder portion grinding while maintaining low shear resistance.
3Manufacturing precision
If the clearance between balls and cage is reduced, then the cage positioning is improved, but the torque of the ball bearing increases
Solution Approach 1:
The guide portion serves as a mediator that transfers the cage guidance function from the balls to the outer ring. This eliminates the need for small clearance between balls and cage, reducing grease shear resistance and thereby reducing the torque required to rotate the ball bearing while maintaining precise cage positioning.
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
The design effectively reduces shear resistance and torque in the ball bearing, extends the useful life of the grease, and prevents cost increases associated with additional finishing on the outer ring.
Implementation Method 1
when the clearance between the balls 93 and the cage 94 is smaller, shear resistance due to the grease is greater
Implementation Method 2
The shear resistance of the grease corresponds to the rotational resistance of the ball bearing 90
Data Source
AI summary
A ball bearing includes an inner ring having an outer periphery in which an inner raceway groove is formed, an outer ring having an inner periphery in which an outer raceway groove is formed, a plurality of balls interposed between the inner raceway groove and the outer raceway groove, and an annular cage that holds the balls. The cage includes an annular portion positioned on one side in an axial direction with respect to the balls and a plurality of cage bar portions that extends from the annular portion toward the other side in the axial direction. Each cage bar portion has a guide portion, and this guide portion positions the cage by coming into contact with the outer raceway groove at one location in a non-contact area other than an area in which the corresponding ball is in contact with the outer raceway groove.