Strain Wave Gear Coupling for Runout Clearance and Anti-Jamming
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Solution Overview
Problem
Strain wave gears in aircraft experience loss of rotation and jamming due to the stacking of radial tolerances, which leads to the loss of essential clearances between moving parts, even with high precision components.
Innovation Solution
A strain wave gear design that includes a rotatable wave generator and a coupler allowing displacement of the driver shaft relative to the wave generator, along with a coupling frame providing clearance in multiple directions to accommodate eccentric runout, and low friction elements to reduce frictional losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high precision parts are used in strain wave gear, then manufacturing precision is improved, but radial tolerance stacking still causes loss of clearances and rotation
Solution Approach 1:
The coupling frame is designed with movable elements that allow dynamic adjustment of the driver shaft position relative to the wave generator. This dynamic capability enables the system to compensate for eccentric runout and maintain clearances during operation, preventing jamming while preserving the benefits of high precision manufacturing.
Solution Approach 2:
The invention introduces adjustable geometric parameters through the coupling frame, specifically the distance and orientation between the driver shaft and wave generator. By allowing these parameters to vary within certain ranges, the system can accommodate tolerance variations and maintain reliable rotation despite radial tolerance stacking in high precision components.
2Device complexity
If rigid coupling is used between driver shaft and wave generator, then structural simplicity is improved, but clearance is lost leading to jamming
Solution Approach 1:
The coupling frame incorporates movable elements that provide controlled flexibility between the driver shaft and wave generator. This dynamic coupling maintains structural simplicity while enabling the necessary clearance accommodation, preventing jamming without requiring complex multi-component coupling mechanisms.
3Reliability
If clearance is increased to accommodate runout, then rotation reliability is improved, but frictional forces increase
Solution Approach 1:
The coupling frame provides localized clearance adjustment only where needed to accommodate eccentric runout, rather than increasing clearance throughout the entire system. This targeted approach maintains rotation reliability while minimizing unnecessary clearance that would increase frictional losses in other areas.
Solution Approach 2:
The movable elements in the coupling frame dynamically adjust clearance as needed during operation, providing just enough space to prevent jamming while minimizing excess clearance that would increase friction. This dynamic optimization balances reliability improvement with energy loss reduction.
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
Prevents loss of rotation and jamming by maintaining clearances and reducing frictional forces, ensuring reliable torque transmission to aircraft control surfaces.
Implementation Method 1
The low friction element may comprise a ball bearing or a low friction coating
Data Source
AI summary
A strain wave gear includes a wave generator configured to contact a spline, the wave generator being rotatable. The strain wave gear also includes a coupler configured to couple a driver shaft to the wave generator. The coupler permits displacement of the driver shaft relative to the strain wave generator.