Cycloid Roller Geometry for Pure Rolling and Higher Torque
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Solution Overview
Problem
Transmission systems face challenges in balancing load capacity, efficiency, and cost, often requiring heavy designs for high load capacity or expensive components for high efficiency, and experience stress concentrations due to small roller bearings or lower efficiency with sliding contacts.
Innovation Solution
The use of cycloid drive apparatuses with pure rolling components, featuring variable-width cutouts and rollers that maintain pure rolling motion, allowing for larger torque capacity with reduced weight and cost, and configurations to compensate for inherent eccentricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If small roller bearings are used, then device size is reduced, but stress concentrations increase
Solution Approach 1:
The patent changes the geometric parameters of the rollers, transitioning from small bearings to larger rollers with varying effective diameters. This parameter change allows the rollers to maintain larger contact areas with the cycloid disk, thereby reducing stress concentrations while still achieving compact device dimensions through the optimized cycloid motion mechanism.
Solution Approach 2:
The patent employs dynamic variation in the effective diameter of the rollers during operation. As the rollers move along the cycloid path, their effective contact radius changes dynamically, allowing optimal stress distribution at different positions in the cycle. This dynamic adaptation enables reduced stress concentrations without requiring uniformly large rollers throughout the entire device.
2Device complexity
If sliding contacts are used, then device complexity is reduced, but efficiency decreases
Solution Approach 1:
The patent substitutes sliding friction mechanics with rolling friction mechanics by implementing rollers that rotate as they move along the cycloid path. This mechanical substitution fundamentally changes the contact mechanism from sliding to rolling, dramatically reducing energy loss due to friction while maintaining relatively simple device architecture through the use of basic rotational components.
3Force
If larger rollers are used, then load capacity increases, but device weight increases
Solution Approach 1:
The patent implements dynamic variation in roller effective diameter throughout the operational cycle. The rollers present larger effective contact areas only when needed for maximum load bearing positions, and smaller effective diameters at other positions. This dynamic adaptation allows the system to achieve high load capacity during critical moments without requiring all rollers to be uniformly large, thereby reducing overall device weight.
Solution Approach 2:
The patent changes the geometric parameters of the rollers from fixed size to variable effective diameter. This parameter change enables the rollers to optimize their load-bearing cross-section dynamically, achieving high load capacity when required while minimizing material usage and weight when full load capacity is not needed, thus resolving the contradiction between load capacity and device weight.
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
An apparatus includes a first ring having an open annular space and a variable-width groove disposed on an interior peripheral surface of the first ring; a second ring rotatable within the open annular space of the first ring, where the second ring has a respective variable-width groove disposed on an exterior peripheral surface of the second ring; and a plurality of rollers disposed between, and configured to roll on, the interior peripheral surface of the first ring and the exterior peripheral surface of the second ring and rotatable therebetween.