Flex Spline End Clamps for Higher-Torque Harmonic Drives
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Solution Overview
Problem
Existing harmonic drives with flex spline shafts face challenges in maximizing usable volume and torque capacity while maintaining efficiency, particularly with pancake-style end sections which offer reduced torque capacity and efficiency compared to cup and hat shaped end sections.
Innovation Solution
The harmonic drive incorporates a flex spline with tapered spline ends and annular channel ends that taper outwardly, secured by tapered clamps. This configuration allows for axial clamping of the flex spline ends within the drive housing, preventing rotation and enhancing torque capacity without reducing the usable volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cup and hat shaped end sections are used, then torque capacity and efficiency are improved, but usable volume is reduced
Solution Approach 1:
The flex spline is divided into three distinct sections: a center section with uniform thickness for torque transmission, and two tapered end sections that reduce thickness to eliminate the need for cup and hat shaped formations. This segmentation allows each part to serve its specific function optimally.
Solution Approach 2:
The solution transitions from modifying the radial dimension (cup and hat shapes) to modifying the axial dimension (tapered thickness). By tapering the end sections axially, the patent achieves secure mounting without reducing the radial usable volume of the drive.
2Volume of moving object
If pancake style end sections are used, then usable volume is improved, but torque capacity and efficiency are reduced
Solution Approach 1:
Different sections of the flex spline have different thickness characteristics: the center section maintains uniform thickness for optimal torque transmission, while the end sections have tapered thickness for secure mounting. This local differentiation optimizes both torque capacity and usable volume.
3Strength
If clamps are applied to secure flex spline, then torque capacity and rotation prevention are improved, but device complexity increases
Solution Approach 1:
The tapered end sections of the flex spline serve a dual function: they provide secure mounting surfaces for the clamps and simultaneously prevent rotation of the flex spline relative to the housing. This self-service feature reduces the need for additional anti-rotation mechanisms.
Data Source
AI summary
A harmonic drive, having a housing extending from first to second outer ends, the housing has radial outer and inner walls that extend axially between the first and second outer ends of the housing to define an annular channel having first and second ends that taper toward the first and second outer ends of the housing; a flex spline that extends axially between first and second ends and has a radial outer surface, and the first and second ends of the flex spline taper radially outwardly, the flex spline is located within the annular channel so that the first end of the flex spline is located within the first end of the annular channel and the second end of the flex spline is located within the second end of the annular channel; and first and second clamps that are clamped against the first and second ends of the annular channel.