Conical Bearing Cage Pockets for Harmonic Drive Vibration Control
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Solution Overview
Problem
Harmonic drives face issues with inconsistent pocket gaps in bearing cages, leading to noise and vibration problems due to varying linear velocities of rolling elements, which existing solutions attempt to address by increasing pocket gaps but result in unstable operation.
Innovation Solution
A ball bearing cage with pockets featuring a substantially conical inner surface that gradually enlarges in the radial direction, allowing adaptive pocket clearance adjustment to match the rolling elements' displacement, suitable for elliptical applications, including harmonic drives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pocket gap is increased to prevent rolling element collision, then the reliability is improved, but the vibration and noise increase
Solution Approach 1:
The pocket gap is made non-uniform with different sizes at different locations around the ellipse. The pocket gap is larger in the load-bearing area where rolling elements move faster and smaller in the non-load-bearing area where they move slower. This local differentiation allows the pocket gap to be optimized for each specific location, preventing collisions in the critical load-bearing zone while minimizing vibration and noise in the non-load-bearing zone.
Solution Approach 2:
The pocket gap is designed to vary dynamically with the position of rolling elements along the elliptical path. The gap size changes continuously around the ellipse to match the varying linear velocity of rolling elements, being larger where velocity is high and smaller where velocity is low. This dynamic adaptation allows the system to maintain reliability throughout the operation cycle while minimizing harmful vibrations and noise.
2Reliability
If the pocket gap is increased to accommodate velocity variations, then the reliability is improved, but the cage guidance performance deteriorates
Solution Approach 1:
The pocket gap is differentiated by location, with smaller gaps in the non-load-bearing area where precise cage guidance is needed and larger gaps in the load-bearing area where collision prevention is critical. This local optimization allows the pocket gap to simultaneously satisfy both cage guidance requirements and collision prevention needs in different zones of the bearing.
Data Source
AI summary
A ball bearing cage having pockets for accommodating spherical rolling elements. At least one of the pockets has a substantially conical inner surface whose diameter is gradually enlarged from the inside to the outside in a specific range in the radial direction of the bearing. On the basis of the above-mentioned cage, the present invention also provides a bearing using the cage, a harmonic drive and related mechanical devices.