Elevator Rope Pressing Shoe for Emergency Traction
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Solution Overview
Problem
Elevators face the risk of slipping between ropes and traction wheels during emergency stops due to excessive polymer material temperature, leading to reduced friction and safety concerns.
Innovation Solution
The implementation of activatable pressing means, such as a pressing shoe, to increase the normal force between the ropes and the traction member, triggered by sensing mechanisms that detect risky conditions like elevated temperatures, ensuring reliable engagement during emergency stops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polymer material is used for the traction surface and rope coating to increase friction and power transmitting ability, then the friction coefficient is improved, but the reliability deteriorates when temperature rises excessively (140-250°C) causing the material to melt or change friction properties
Solution Approach 1:
The patent changes the material parameter of the traction surface from polymer to metal, which has different thermal and frictional properties. The metal traction surface maintains stable friction characteristics at high temperatures (140-250°C) where polymer materials would melt or change properties, thus resolving the reliability issue while maintaining adequate friction for power transmission
Solution Approach 2:
The patent creates a composite system where the traction surface is made of metal with a specific surface treatment (e.g., carbide coating or textured surface) that provides high friction characteristics. This metal-based composite approach combines the high-temperature stability of metal with enhanced friction properties, overcoming the limitations of pure polymer materials
2Speed
If aggressive braking is applied during emergency stopping to achieve sudden stop, then the stopping performance is improved, but the reliability deteriorates due to increased risk of slipping between ropes and traction wheel
Solution Approach 1:
The patent changes the friction parameter by using a metal traction surface with optimized surface properties (e.g., carbide coating, textured surface, or increased surface hardness) that provides higher and more stable friction coefficient. This allows aggressive braking during emergency stops without causing slipping, as the metal surface maintains consistent friction characteristics under high stress and temperature conditions
Solution Approach 2:
The patent optimizes the surface geometry of the traction wheel by creating a textured or patterned surface (e.g., ribs, grooves, or dimensional variations) that increases the effective contact area and friction. This surface curvature modification enhances the rope-traction wheel engagement, preventing slipping during emergency braking while allowing rapid stopping performance
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 solution effectively reduces the likelihood of slipping and enhances safety by maintaining traction during critical situations, particularly during emergency stops, by selectively activating the pressing means when predetermined conditions are met.
Implementation Method 1
The suspension ropes are typically engaged frictionally by the traction wheel. The front side surface and/or the traction surface of the rotatable traction member is made of material comprising polymer.
Implementation Method 2
The engagement between the ropes and the traction wheel is frictional. By polymer based coating, it is for example possible to adjust, usually aiming to increase, the power transmitting ability over the frictional engagement.
Data Source
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AI summary
The invention relates to an elevator comprising a hoistway (H); an elevator car (1) vertically movable in the hoistway (H); at least one rope (3a,3b,3c) connected to the car (1); a rotatable traction member (6) comprising a circumferential traction surface (4a, 4b, 4c) for each of the at least one rope (3a,3b,3c); each of the at least one rope (3a,3b,3c) passing around the rotatable traction member (6) and having a front side surface (5a,5b,5c) resting against a circumferential traction surface (4a, 4b, 4c) of the traction member (6), the front side surface (5a,5b,5c) and/or the traction surface (4a, 4b, 4c) of the rotatable traction member (6) being made of material comprising polymer; and a drive machinery (M) for controlling rotation of the rotatable traction member (6); and activatable pressing means (11) for pressing the at least one rope (3a,3b,3c) against the circumferential traction surface (4a, 4b, 4c) of the traction member (6) which comprise a pressing shoe (12) mounted on the back side of and out of contact with the rope section (13a,13b,13c) of each of said at least one rope (3a,3b,3c), which rope section (13a,13b,13c) rests against the rotatable traction member (6), the pressing shoe (12) being movable towards the back side surface (9a, 9b, 9c) of said rope section (13a,13b,13c); and actuating means (14,15) activatable to move the pressing shoe (12) towards the back side surface (9a, 9b, 9c) of said rope section (13a,13b,13c) such that the pressing shoe (12) moves into contact with and presses the rope section (13a,13b,13c) against the circumferential traction surface (4a, 4b, 4c) of the traction member (6); and activating means (10,10',10",20,100) for activating the actuating means (14,15) to move the pressing shoe (12) towards the back side surface (9a, 9b, 9c) of said rope section (13a,13b,13c).