Elevator Belt Sheave Tracking Grooves for Debris-Tolerant Alignment
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Solution Overview
Problem
Elevator systems face challenges in providing sufficient strength and stiffness per sheave width, particularly due to the accuracy of belt tracking, which is affected by machine sheave alignment, hoistway rail positioning, and building sway or drift, especially when using multiple belts as load-bearing members.
Innovation Solution
A belt and sheave assembly with laterally spaced tracking grooves and debris channels, featuring tension members arranged along the belt width, with tracking features and a jacket material configuration that allows for improved belt positioning and reduced wear, including triangular cross-sectional shapes and materials with varying coefficients of friction for enhanced tracking and debris management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple belts are utilized as load bearing members to increase system capacity, then the overall strength and stiffness of the elevator system is improved, but the accuracy of belt tracking deteriorates due to cumulative alignment errors and building sway
Solution Approach 1:
The belt is segmented into multiple independent tracking features (protrusions) that engage with corresponding grooves on the sheave. Each tracking feature independently maintains belt position, so that even if one feature experiences misalignment, the other features continue to provide tracking stability. This segmentation allows the system to accommodate building sway and alignment variations while maintaining overall tracking accuracy.
Solution Approach 2:
The tracking features are designed with specific geometric parameters (triangular cross-section, lateral spacing, radial depth) that optimize both tracking accuracy and load distribution. The grooves on the sheave are shaped to complement these features, creating a precise mating relationship that maintains belt positioning while accommodating thermal expansion and wear through controlled parameter variations.
2Productivity
If belts are positioned closely together to maximize sheave width utilization, then the productivity and space efficiency is improved, but the susceptibility to belt split increases due to increased loading on tracking features
Solution Approach 1:
The tracking features are positioned at specific locations along the belt width, with the space between features (tracking feature gap) strategically located to allow debris egress. The local geometry of each tracking feature is optimized to distribute loads evenly, with the triangular cross-section providing both positioning accuracy and load-bearing capacity. This local optimization prevents stress concentration that could lead to belt split while maintaining close belt spacing.
Solution Approach 2:
The debris channel is extracted as a separate functional element within the groove structure, positioned to receive and remove debris that accumulates during operation. By removing debris from the tracking interface, the system prevents debris-induced loading and wear that could compromise belt integrity, thereby maintaining reliability even when belts are closely spaced.
3Manufacturing precision
If tracking grooves are designed with deep radial extent to ensure proper tracking, then the tracking accuracy is improved, but the accumulation of debris in the grooves increases
Solution Approach 1:
Instead of designing the groove to simply contain the tracking feature, the groove is designed with an inverted logic: the tracking feature fits into the groove with intentional clearance, and the groove geometry is configured to actively eject debris rather than trap it. The radially inwardmost extent of the groove creates a debris channel that uses the rotational motion and centrifugal forces to throw debris outward, away from the tracking interface.
Solution Approach 2:
The rotational motion of the sheave, which could potentially embed debris into the tracking interface, is converted into a beneficial ejection mechanism. The groove geometry is designed so that the centrifugal force and rotational motion actively remove debris from the tracking zone, transforming a potentially harmful effect into a self-cleaning mechanism that maintains tracking accuracy without requiring external cleaning systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution ensures tight belt spacing on the traction sheave, reduces loading on tracking features, improves wear performance, and minimizes the susceptibility to belt split, thereby enhancing the overall strength and stiffness of the elevator system while maintaining smooth operation.
Implementation Method 1
The plurality of tracking features are laterally spaced across the belt width. Each tracking feature is configured to be received in a tracking groove of the plurality of tracking grooves
Implementation Method 2
a debris channel located in a tracking groove of the plurality of tracking grooves defining a radially inwardmost extent of the tracking groove
Data Source
Figure 1
Figure 2~3A
Figure 3B
AI summary
A belt and sheave assembly for an elevator system includes a sheave having a plurality of tracking grooves laterally spaced across a sheave width, and a debris channel located in a tracking groove of the plurality of tracking grooves defining a radially inwardmost extent of the tracking groove. The assembly further includes a belt having a plurality of tension members arranged along a belt width and extending longitudinally along a length of the belt, a jacket at least partially enclosing the tension members, the jacket defining a side of the belt configured to interface with the sheave, and a plurality of tracking features extending from the side of the belt. The tracking features are laterally spaced across the belt width. Each tracking feature is configured to be received in a tracking groove, and each tension member is laterally offset from each of the tracking features.