Flat-Belt Linear Actuator Layout Without Fleet Angle Misalignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Flat belts in linear actuation systems are sensitive to fleet angle misalignments, which significantly reduce their service life and performance, especially in high-reduction block and tackle topologies, making them unsuitable for applications requiring mechanical reduction beyond 4:1.
Innovation Solution
A linear actuator system design that eliminates fleet angles by using sheaves with non-constant spacing and different centerline diameters, coupled to shafts that translate along a main drive axis, allowing for high-performing flat belts to be used in block and tackle topologies with sheave geometries that maintain a common axis and eliminate fleet angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If block and tackle topology is used for mechanical reduction, then force multiplication is improved, but fleet angle misalignment increases causing belt service life to deteriorate
Solution Approach 1:
The patent applies asymmetry by configuring sheaves with non-constant spacing and different centerline diameters. Specifically, the first plurality of sheaves have different diameters than the second plurality of sheaves, and they are spaced non-constant distances apart. This asymmetric arrangement eliminates fleet angles while maintaining the mechanical reduction ratio, thereby preserving belt service life while achieving force multiplication.
Solution Approach 2:
The patent changes geometric parameters of the sheave system to eliminate fleet angles. By adjusting the spacing between sheaves to be non-constant and setting different centerline diameters for sheaves in different pluralities, the system maintains belt alignment perpendicular to sheave surfaces throughout operation. This parameter optimization allows block and tackle topology to be used without the harmful fleet angle effects.
2Force
If high reduction ratio (greater than 4:1) is implemented, then mechanical advantage is improved, but fleet angle sensitivity causes system reliability to worsen
Solution Approach 1:
The patent uses asymmetric sheave configuration where the first plurality of sheaves have different diameters than the second plurality, with non-constant spacing between them. This asymmetric design enables high reduction ratios greater than 4:1 while eliminating fleet angles, thus maintaining system reliability even at high mechanical advantage levels.
Solution Approach 2:
The patent implements a dynamic sheave arrangement where the spacing between sheaves is non-constant and diameters vary across the pluralities. This dynamic geometric configuration allows the system to accommodate high reduction ratios without creating fleet angle misalignments, maintaining belt integrity and system reliability throughout the full range of motion.
3Power
If conventional block and tackle design is used, then power transmission efficiency is improved, but fleet angle introduction reduces belt durability
Solution Approach 1:
The patent applies asymmetric sheave design with non-constant spacing and varying diameters across the two pluralities. This configuration maintains efficient power transmission through the block and tackle topology while eliminating fleet angles that would otherwise cause premature belt failure, thereby preserving both power efficiency and belt durability.
Solution Approach 2:
The patent optimizes geometric parameters including non-constant sheave spacing and different centerline diameters to eliminate fleet angles. These parameter changes maintain the mechanical advantage and power transmission efficiency of block and tackle while preventing the fleet angle-induced wear that would reduce belt durability.
Data Source
AI summary
Disclosed herein are methods, systems, and components for the design of a flat belt based block and tackle design that is theoretically free of fleet angles. A mapping technique forms a set of planar positions for the centerlines of the free spans that provides a plurality of sheave geometries, which reside on a common axis and spans that are free of fleet angles at the sheave engagement interfaces. This permits the use of high-performing flat belts in high-reduction block and tackle topologies, with the principal benefits of an extended service life, high power transmission efficiency, more effective traction power transfer, and a compact machine design.