Strain Wave Gear Bearing Layout for Flexible Spline Stress Relief
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Solution Overview
Problem
Strain wave gear systems experience high levels of stress on the flexible spline due to deformation and torque transmission, leading to wear and reduced system lifetime, necessitating frequent maintenance.
Innovation Solution
Incorporation of a bearing arrangement with a plurality of bearings and a cage to support the flexible spline across a greater axial length, reducing stress and wear by distributing the load more evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the flexible spline is closely fitted between the wave generator and circular spline to achieve high gear ratio, then the gear ratio is improved, but the stress on the flexible spline increases
Solution Approach 1:
A bearing arrangement is introduced as an intermediary component between the wave generator and flexible spline. This bearing arrangement includes multiple bearings distributed along the axial length of the flexible spline, which mediate the interaction between the rotating wave generator and the flexible spline, reducing direct stress concentration while maintaining the closely fitted configuration necessary for high gear ratio.
Solution Approach 2:
The bearing arrangement is segmented into multiple discrete bearings distributed along the axial length of the flexible spline rather than using a single continuous support. This segmentation allows the load to be distributed across multiple contact points, reducing stress concentration at any single location while maintaining the overall structural integrity and gear ratio performance.
2Power
If the flexible spline deforms to the non-circular shape of the wave generator to achieve torque transmission, then the torque transmission is improved, but the wear of the flexible spline increases
Solution Approach 1:
The bearing arrangement is pre-installed and positioned along the axial length of the flexible spline before operation begins. These bearings provide preliminary support and guidance to the flexible spline as it deforms, preventing excessive wear during the deformation cycle while maintaining the necessary torque transmission capability through the non-circular wave generator configuration.
3Adaptability or versatility
If the flexible spline is required to both deform and transmit torque simultaneously, then the gear functionality is improved, but the lifetime of the flexible spline is reduced
Solution Approach 1:
The bearing arrangement acts as an intermediary support system that enables the flexible spline to simultaneously perform deformation and torque transmission functions. By providing distributed axial support, the bearings reduce the mechanical burden on the flexible spline, allowing it to maintain its dual functionality while extending its service life through reduced stress and wear.
Data Source
AI summary
A strain wave gear system includes a circular spline arranged around a longitudinal axis, a flexible spline within and coaxial with the circular spline and a wave generator within and coaxial with the flexible spline. The wave generator is non-circular in a plane perpendicular to the longitudinal axis. The flexible spline is arranged to flex in response to rotation of the wave generator. The wave generator is configured to rotate about the longitudinal axis such that the flexible spline is arranged to selectively engage with the circular spline. The strain wave gear system further includes a bearing arrangement between and coaxial with the wave generator and the flexible spline. The bearing arrangement comprises a plurality of bearings and a cage arranged to retain the plurality of bearings. The plurality of bearings are located at more than two axial positions within the cage.