Layered Elevator Belt Structure for Lower Sheave Bending Stress
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Solution Overview
Problem
Elevator systems using unidirectional fiber composite load bearing tension members experience high bending stress when wrapped around traction sheaves, leading to substantial bending stiffness and potential mechanical inefficiencies.
Innovation Solution
A load bearing tension member design featuring a plurality of fibers embedded in a matrix material, offset and staggered across the tension member width, encapsulated in an elastomeric jacket, which reduces bending resistance and allows for smaller sheave diameters, thereby optimizing the elevator system's space usage and mechanical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If unidirectional fiber composite construction is used, then light weight and high strength are achieved, but bending stiffness increases substantially
Solution Approach 1:
The patent applies asymmetry by offsetting the neutral axis from the geometric center of the belt cross-section. This is achieved by positioning the load-bearing tension elements (unidirectional fibers) asymmetrically within the elastomeric matrix, creating a structure where the neutral axis does not coincide with the geometric center. This asymmetric configuration reduces bending stress while maintaining the high strength benefits of unidirectional fiber construction.
Solution Approach 2:
The patent changes the structural parameters of the composite belt by varying the distribution and positioning of tension elements within the elastomeric matrix. Specifically, the tension elements are arranged with different spacing and offset distances from the neutral axis, allowing optimization of bending characteristics while preserving tensile strength. This parameter modification enables the belt to achieve both high strength and reduced bending stiffness.
2Weight of moving object
If unidirectional fiber composite construction is used, then light weight is achieved, but bending stiffness increases substantially
Solution Approach 1:
The asymmetric arrangement of tension elements offsets the neutral axis, creating a configuration that reduces bending stress. This asymmetric structure maintains the lightweight advantage of unidirectional fiber composites while mitigating the harmful effect of high bending stiffness through optimized geometric distribution of load-bearing elements.
3Strength
If high bending stiffness is produced, then structural strength is maintained, but space efficiency decreases requiring larger sheave diameters
Solution Approach 1:
The patent modifies structural parameters by adjusting the offset distance and spacing of tension elements to reduce bending stiffness to an optimal level. This parameter optimization allows the use of smaller sheave diameters, improving space efficiency while maintaining sufficient structural strength for safe elevator operation. The neutral axis offset is specifically tuned to achieve the desired balance between strength and compactness.
Data Source
AI summary
A load bearing tension member for an elevator system includes a plurality of tension elements arrayed across a tension member width. The tension elements are offset from a tension member central axis, the central axis bisecting a tension member thickness and extending across the tension member width. The tension elements include a plurality of fibers extending along a length of the tension element, and a matrix material in which the plurality of fibers are embedded. A jacket at least partially encapsulates the plurality of tension elements.