Magnetorheological Rope Adhesion Control for Elevator Traction
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Solution Overview
Problem
Existing suspension and traction systems in elevators and similar applications face challenges in controlling adhesion between ropes or belts and pulleys, particularly in preventing unwanted twisting and stress due to uneven stress distribution and noise caused by adhesion, which is not effectively variable or controllable.
Innovation Solution
A suspension and traction element with a paramagnetic polymeric matrix and magnetic particles, where the proportion of magnetic particles is at least 15%, is used, and an electromagnet applies a magnetic field to control adhesion based on contact type, pulley geometry, and operating conditions, with the magnetic field direction and intensity adjusted for traction and deflection pulleys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesion between suspension and traction element and pulley is increased to increase traction capacity, then traction capacity is improved, but the rope will slide insufficiently causing winding accidents when car is on top floor
Solution Approach 1:
The patent applies magnetorheological material in the pulley lagging that can dynamically change its adhesion properties in response to magnetic field variations. During normal operation, high adhesion is maintained for traction. When the car reaches the top floor, the magnetic field is adjusted to reduce adhesion, allowing the rope to slide and prevent winding accidents. This dynamic adjustment resolves the contradiction between needing high traction capacity and preventing winding accidents.
2Strength
If adhesion between rope and pulley is increased to prevent sliding, then traction is improved, but twisting stresses increase due to fleet angle in deflection pulleys
Solution Approach 1:
The magnetorheological material allows dynamic control of adhesion between the rope and deflection pulley. When fleet angle occurs causing the rope to touch the side of the groove, the magnetic field can be adjusted to minimize adhesion, reducing twisting and torsional stresses. During normal aligned operation, adhesion can be higher to maintain traction. This dynamic adjustment resolves the contradiction between traction and torsional stress prevention.
3Strength
If adhesion between rope and pulley is high to ensure traction, then traction capacity is improved, but noise increases due to unequal stress distribution in deflection pulleys
Solution Approach 1:
The magnetorheological material in the pulley lagging enables dynamic adjustment of adhesion properties. In deflection pulleys where unequal stress distribution causes noise, the magnetic field can be modulated to optimize adhesion, reducing the harmful noise effects while maintaining adequate traction. This resolves the contradiction between high traction capacity and noise reduction.
4Reliability
If adhesion is minimized to allow rope sliding and prevent twisting, then reliability is improved, but traction capacity decreases
Solution Approach 1:
The magnetorheological material provides dynamic control over adhesion, allowing the system to switch between high adhesion (for traction) and low adhesion (for sliding and preventing twisting/winding) based on real-time operational conditions and magnetic field adjustments. This resolves the contradiction by making adhesion variable rather than fixed.
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 allows for active control of adhesion, reducing twisting stresses and noise by varying the mechanical behavior of the rope-pulley interaction, ensuring safe and efficient operation by minimizing adhesion when necessary and maximizing it during normal operation.
Implementation Method 1
Magnetorheological materials respond to the application of a magnetic field with a change in its mechanical behavior and they are formed by magnetizable particles in a paramagnetic matrix. This change is due to the magnetic forces generated by interactions between magnetic dipoles caused by the application of an external magnetic field.
Data Source
Figure 1a~1b
Figure 2~3
AI summary
A suspension and traction element comprising a load bearing section (1) provided with at least one wire and a sheath (2) at least partially covering the load bearing section (1), the sheath (2) comprises a paramagnetic and polymeric material matrix and magnetic particles dispersed in said matrix in a proportion of at least 10% by volume. A system and an elevator incorporating said element for active friction respectively traction control between said element and a pulley, and a traction control method using said element are disclosed, too.