Twisted Flat Belt Geometry for Uniform Tension in Angular Drives
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Solution Overview
Problem
Flat belts in angular drive systems experience premature failure due to misalignment of sheaves, leading to uneven tension distribution, sidewall abrasion, and reduced service life, especially when subjected to aggressive twist geometries.
Innovation Solution
Implementing a twisted geometry in the belt with a complimentary fleet angle to counteract the uneven tension distribution, using a freely rotating sheave or driven sheave to misalign the belt's geometric centerline, thereby normalizing tension and reducing sidewall abrasion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a flat belt is subjected to aggressive twist geometries with high twist ratios, then the design envelope becomes more compact, but the service life of the belt is severely reduced due to uneven tension distribution and sidewall abrasion
Solution Approach 1:
The patent applies asymmetry by intentionally misaligning the sheave relative to the belt centerline by a specific fleet angle. This asymmetric positioning creates a compensating tension distribution that counteracts the uneven tension caused by aggressive twist geometries, thereby extending belt service life while maintaining compact design
Solution Approach 2:
The patent changes the geometric parameters of the belt system by implementing specific twist ratios (reducing them to 20:1 or less) and introducing a complimentary fleet angle parameter. These parameter changes optimize the balance between compactness and service life by controlling the degree of twist and misalignment
2Reliability
If the sheave is misaligned to create a fleet angle in a twisted belt span, then the tension distribution is normalized and sidewall abrasion is reduced, but the alignment precision requirements increase
Solution Approach 1:
The patent applies preliminary anti-action by pre-calculating and pre-setting the optimal fleet angle during the design phase. This pre-determined misalignment counteracts the harmful effects of twist geometry before the belt enters service, normalizing tension distribution without requiring high-precision alignment during installation or operation
3Duration of action of moving object
If the twist ratio is reduced to extend service life, then sidewall abrasion and tension unevenness are minimized, but the design envelope becomes less compact
Solution Approach 1:
The patent uses asymmetric sheave positioning (fleet angle) to compensate for the limitations imposed by reduced twist ratios. This allows the system to achieve both compact dimensions and extended service life by using the misalignment to optimize tension distribution in the constrained geometry
Data Source
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.