Variable-Section Elevator Safety Spring for Consistent Braking Force
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Solution Overview
Problem
Conventional elevator safety springs require thicker material for increased braking force, leading to higher material costs and manufacturing complexities, and necessitate multiple tooling and configurations for varying performance parameters, which is costly and difficult to manage.
Innovation Solution
A curved spring design with a cavity extending along its length and varying cross-sectional dimensions, made from high-strength steel, using casting or three-dimensional printing, which maintains a constant moment of inertia to spring force ratio and reduces material thickness variability, facilitating uniform deflection and easier heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the thickness of the spring material is increased to achieve larger braking force, then the braking force increases, but the material cost and manufacturing difficulty increase
Solution Approach 1:
The spring features a non-uniform cross-section with varying thickness along its length, with the thickest portions located at the ends and thinner portions in the middle. This local variation in quality allows the spring to achieve the required braking force through strategic material distribution rather than uniform thickness, reducing overall material usage and manufacturing complexity while maintaining necessary strength at critical locations.
Solution Approach 2:
The spring utilizes a composite structure combining material of different thicknesses within a single component, creating an optimized mass distribution that achieves high braking force output without requiring uniformly thick material throughout the entire spring body.
2Force
If the thickness of the spring material is increased to achieve larger braking force, then the braking force increases, but the material cost increases
Solution Approach 1:
The spring features a non-uniform cross-section with varying thickness along its length, with the thickest portions located at the ends and thinner portions in the middle. This local variation in quality allows the spring to achieve the required braking force through strategic material distribution rather than uniform thickness, reducing overall material usage and manufacturing complexity while maintaining necessary strength at critical locations.
Solution Approach 2:
The spring utilizes a composite structure combining material of different thicknesses within a single component, creating an optimized mass distribution that achieves high braking force output without requiring uniformly thick material throughout the entire spring body.
3Force
If larger springs are used to achieve larger braking force, then the braking force increases, but the complexity of tooling and processing increases
Solution Approach 1:
The spring features a non-uniform cross-section with varying thickness along its length, with the thickest portions located at the ends and thinner portions in the middle. This local variation in quality allows the spring to achieve the required braking force through strategic material distribution rather than uniform thickness, reducing overall material usage and manufacturing complexity while maintaining necessary strength at critical locations.
Solution Approach 2:
The spring design incorporates dynamic considerations in its variable cross-section, optimizing the distribution of material to handle varying stress conditions during operation, which simplifies the tooling and processing requirements compared to rigid uniform-thickness designs.
4Adaptability or versatility
If multiple spring sizes are used for different elevator safety configurations, then different performance parameters are achieved, but the number of tools and manufacturing steps increases
Solution Approach 1:
The variable cross-section spring design serves multiple functions and can be adapted to different elevator safety configurations by modifying the cavity dimensions and cross-sectional profile rather than requiring entirely different spring sizes. This multi-functional approach reduces the number of specialized tools and manufacturing steps needed.
Solution Approach 2:
The spring achieves different performance parameters through changes in geometric parameters (cavity dimensions, cross-sectional thickness distribution) rather than requiring different spring sizes, allowing a single manufacturing process to produce springs with varied performance characteristics.
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 design results in a lighter, less costly, and simpler-to-manufacture spring that maintains desired performance characteristics, reducing material costs and manufacturing complexity while providing a consistent braking force.
Implementation Method 1
The curved shaped body flexes outwardly responsive to the brake members moving into the braking position while urging the brake members toward the inside of the C-shape
Implementation Method 2
a ratio of a moment of inertia of the spring to the spring force is essentially constant along the length
Data Source
AI summary
An illustrative example spring includes a curved shape body having a length. The body includes a cavity that extends along at least a majority of the length. The body has a cross-section across the length that is different at a plurality of locations on the body along the length.