Elevator Safety Gear Roller with Bronze Fitting for Seizing Prevention
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Solution Overview
Problem
Existing braking or catching devices for elevator cars experience seizing issues due to high pressures between steel components, leading to premature failure and unreliable operation.
Innovation Solution
The solution involves a braking or catching device with a pressure body featuring a fitting made of bearing material, where the roller partially slides on the bearing material and partially on a harder material, ensuring consistent friction conditions and preventing seizing. This design includes a bolt of bearing material held in a torsion-proof manner within the pressure body, and the roller has profiling to ensure it rolls on the guide rail at the end position, reducing wear and increasing braking force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high pressure is applied between steel roller and steel guide rail to increase braking force, then braking effectiveness is improved, but seizing occurs between the steel components
Solution Approach 1:
The guide rail is provided with a bronze coating in the specific region where the roller contacts it during braking. This creates a local area with different material properties (lower friction coefficient, better wear resistance) exactly where high pressure contact occurs, allowing high braking forces without seizing between steel components
Solution Approach 2:
The bronze coating acts as an intermediary layer between the steel roller and the steel guide rail. This intermediate material layer prevents direct steel-to-steel contact under high pressure, eliminating the seizing problem while still transmitting the necessary braking force through the bronze interface
2Reliability
If the roller slides entirely on bronze coating to prevent seizing, then wear resistance is improved, but braking force is reduced due to lower friction
Solution Approach 1:
The roller has different surface characteristics at different locations: the main contact area has a friction surface for braking, while the end area has a smoother sliding surface that contacts the bronze coating. This local differentiation allows the roller to generate braking force through friction on the guide rail while the bronze-coated region prevents seizing during the sliding phase
Solution Approach 2:
The contact interface is segmented into two functional zones: a friction zone where the roller generates braking force through controlled friction, and a sliding zone where the roller contacts the bronze coating to prevent seizing. This segmentation allows both high braking force and wear resistance to coexist by assigning different functions to different parts of the contact surface
3Force
If traditional steel-on-steel design is used to maximize braking force, then braking effectiveness is improved, but wear on guide rail and safety gear increases
Solution Approach 1:
The bronze coating serves as a sacrificial intermediary layer that protects the expensive steel guide rail from direct contact and wear. The softer bronze material absorbs the wear instead of the guide rail, significantly reducing material loss on the critical guide rail components while maintaining effective braking force transmission
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
This configuration significantly improves tribological conditions, allowing for higher braking forces without seizing, with the device capable of repeated use while minimizing wear, and providing a higher braking effect compared to traditional steel-on-steel designs.
Implementation Method 1
The roller (9) in its end position partially slides on the bearing material and partially on the harder material of the pressure body (19)
Implementation Method 2
the pressure body (19) that is provided for assembly on the elevator car and supports the brake roller is designed here in such a way that it itself exerts a defined spring effect
Data Source
Figure 1~3
Figure 3B
Figure 4~5
AI summary
The mechanism (14) has a gap-forming section (20a) of a pressure element (19) and associated guide rails forming a gap (20). A roll (9) is pulled into the gap during a deceleration or catching action. A stop limits the distance by which the roll is pulled into the gap, and predefines a final position for the roll. The gap is locally provided with a fitting (33) which is designed and arranged such that the roll partially slides on a bearing material in the final position of the roll, and partially slides on a harder material of the pressure element forming remaining sliding surface.