Twisted Flat Belt Geometry for Uniform Tension in Angular Drives
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Solution Overview
Problem
Flat belts in angular drive systems with aggressive twist geometries experience significant reduction in service life due to uneven tension distribution and sidewall abrasion, limiting their design flexibility and compactness compared to untwisted geometries.
Innovation Solution
Implementing a complimentary fleet angle that normalizes the tension distribution in twisted flat belts, allowing for aggressive twist ratios like 7:1 with minimal service life penalty, by strategically misaligning sheaves to distribute tension uniformly across the belt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If aggressive twist geometries are implemented in flat belt drive systems, then the design envelope is reduced and compactness is improved, but the service life is significantly reduced due to uneven tension distribution and sidewall abrasion
Solution Approach 1:
The patent applies asymmetry by intentionally introducing a fleet angle (angular misalignment) between the belt centerline and sheave tangent. This asymmetric configuration compensates for the uneven tension distribution caused by aggressive twists, normalizing the tension across the belt width and preventing sidewall abrasion while maintaining compact design envelopes with twist ratios as low as 7:1
Solution Approach 2:
The patent changes the geometric parameters of the sheave arrangement by specifying precise fleet angles based on twist ratio and sheave diameter. By adjusting these angular parameters, the system achieves normalized tension distribution in twisted belts, extending service life by two orders of magnitude while maintaining aggressive twist geometries for compactness
2Duration of action of moving object
If fleet angle is increased to compensate for twist-induced tension unevenness, then tension distribution is normalized and service life is extended, but sidewall contact and abrasion may increase
Solution Approach 1:
The patent converts the potentially harmful effect of fleet angle (which could cause sidewall contact) into a beneficial force. By carefully calculating and applying the correct fleet angle magnitude, the system uses the angular misalignment to normalize tension distribution and extend service life, while the sheave design with proper flange positioning prevents excessive sidewall abrasion
Data Source
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AI summary
This disclosure relates to methods and apparatuses of employing belts for an angular drive. A twisted geometry is applied to a first free span of the belt. A sheave supports the first free span of the belt at a first extremity of the first free span and sheave is at least one of positioning and orienting the rotating sheave or the driven sheave so as to misalign a geometric centerline of the first free span of belt at a given fleet angle with respect to a second extremity of the first free span.