Hybrid Elevator Compensation Member for Cost-Strength Balance
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Solution Overview
Problem
High rise elevator systems face challenges in balancing the strength and cost of lightweight suspension members, as using the same member for both suspension and tie-down results in excess strength on the tie-down side, increasing system cost and requiring materials with higher strength than necessary.
Innovation Solution
A compensation and tie-down member is designed with a combination of lightweight and heavier weight tension elements, each having different tensile strength per unit mass and length, arranged to balance mass and strength, using materials like carbon fibers and steel wires, and optionally encapsulated in jackets to stabilize elevator systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the same lightweight suspension member is used for both suspension and tie-down, then the strength-to-mass ratio is improved, but the tie-down strength exceeds requirements by approximately a factor of 2, increasing system cost
Solution Approach 1:
The compensation member is segmented into multiple independent tension elements with different properties. Specifically, it includes at least one lightweight tension element (e.g., carbon fiber reinforced polymer) and at least one conventional steel wire rope tension element, allowing each element to contribute differently to the overall strength and mass characteristics of the compensation member
Solution Approach 2:
Different regions or components of the compensation member have different material properties. The lightweight tension element provides high strength-to-mass ratio where needed, while the steel wire rope tension element provides adequate strength where lower strength-to-mass ratio is acceptable, creating a heterogeneous structure optimized for specific functional requirements
2Strength
If wire rope with same mass per unit length as lightweight suspension member is used for tie-down, then the strength requirement is met, but the strength exceeds what is required by approximately a factor of 2, increasing cost
Solution Approach 1:
Instead of using a single tension element that provides excessive strength (and thus excessive cost), the invention uses a combination where the steel wire rope tension element provides partial strength contribution. This partial action approach allows the system to meet the minimum strength requirement without the penalty of over-engineering with uniformly high-strength materials throughout
Solution Approach 2:
The compensation member functions as a composite system combining two different tension element types: lightweight high-strength-to-mass materials (such as carbon fiber reinforced polymer) and conventional steel wire rope. This composite approach allows the system to achieve the required overall strength while optimizing the mass and cost characteristics by strategically combining materials with different properties
Data Source
AI summary
A compensation and tie-down member for an elevator system includes one or more lightweight compensation tension elements having a first tensile strength/unit mass/unit length, and one or more heavier weight compensation tension elements having a second tensile strength/unit mass/unit length less than the first tensile strength/unit mass/unit length.