Bi-Stable Elevator Brake Actuator for Variable Rail Gaps
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Solution Overview
Problem
Elevator safety brakes with magnetic actuators face inefficiencies due to varying gaps between actuators and guide rails, leading to noise and wear, as existing designs struggle to maintain effective braking across different gap sizes.
Innovation Solution
A bi-stable brake actuator with a movable core and permanent magnet assembly that moves orthogonally to the actuator axis, utilizing a coil to generate magnetic fields and an elastic element to facilitate movement, allowing for improved attraction and performance across small and large gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If sliding guides are used to reduce excessive gaps between actuators and rails, then the gap is reduced, but noise and wear are introduced
Solution Approach 1:
The patent replaces the mechanical sliding guide system with a magnetic field-based actuation system. The magnetic actuator uses electromagnetic fields to move the brake shoes toward the rails without physical contact, eliminating the mechanical sliding components that cause noise and wear while maintaining the ability to reduce excessive gaps.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the actuator and the rail. Instead of direct mechanical contact through sliding guides, the magnetic field mediates the interaction, allowing for precise control of the gap distance without the harmful effects of mechanical friction and contact.
2Reliability
If magnetic actuators are used in safety brakes, then braking performance is improved, but the gap between actuators and rails must be well defined
Solution Approach 1:
The patent employs a dynamic magnetic actuator system that can adjust the gap distance between the actuator and the rail in real-time. The bi-stable mechanism allows the system to dynamically switch between different gap configurations, adapting to varying conditions without requiring a precisely fixed gap from manufacturing.
Solution Approach 2:
The patent changes the magnetic field parameters (strength, polarity, distribution) to maintain effective braking across different gap distances. By adjusting these parameters, the system compensates for variations in the gap without requiring high manufacturing precision, thus maintaining reliable braking performance.
3Ease of manufacture
If the gap between actuators and rails varies due to machining tolerances and relative sizes, then manufacturing flexibility is improved, but braking effectiveness deteriorates
Solution Approach 1:
The patent incorporates feedback mechanisms that detect the actual gap distance between the actuator and the rail, then adjust the magnetic field parameters accordingly. This feedback loop ensures that braking effectiveness is maintained despite variations in gap distance caused by machining tolerances or component size variations.
Solution Approach 2:
The patent designs a universal magnetic actuator system that can effectively operate across a wide range of gap distances. The bi-stable mechanism and adjustable magnetic parameters allow the same actuator design to function reliably whether the gap is small or large, eliminating the need for precision-matched components.
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 bi-stable brake actuator enhances the performance of elevator safety brakes by maintaining effective braking across varying gaps, reducing noise and wear, and improving magnetic efficiency, even with gaps exceeding 3.6 mm.
Implementation Method 1
a coil disposed in the fixed core and configured to generate magnetic fields of opposite polarities when supplied with opposing currents, respectively
Implementation Method 2
a permanent magnet assembly. The permanent magnet assembly is disposed to move between first and second positions in accordance with the coil being supplied with the opposing currents, respectively
Data Source
AI summary
A bi-stable brake actuator is provided and includes a fixed core movable in a first direction, a coil disposed in the fixed core and configured to generate magnetic fields of opposite polarities when supplied with opposing currents, respectively, a movable core disposed to move between retracted and extended positions with respect to the fixed core and the coil in exclusively a second direction defined orthogonally with respect to the first direction and a permanent magnet assembly. The permanent magnet assembly is disposed to move between first and second positions in accordance with the coil being supplied with the opposing currents, respectively.