Elevator Safety Brake Actuator for Large-Airgap Overspeed Braking
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Solution Overview
Problem
Existing elevator emergency brake systems face challenges in providing cost-effective and reliable overspeed braking, especially in high-speed elevators with larger airgaps between the elevator car and the hoistway rail, where traditional mechanical linkages are inefficient and costly to maintain.
Innovation Solution
An electronic actuator system with an electromagnet assembly and a magnet assembly that includes elongated block legs and core stub legs, configured to engage and retract from the hoistway rail efficiently, utilizing a system housing and return biasing members to manage magnetic attraction and repulsion for effective braking, even over larger airgaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional mechanical linkages are used for emergency braking, then the system is reliable for low-speed elevators, but the system becomes inefficient and costly to maintain for high-speed elevators with larger airgaps
Solution Approach 1:
The patent replaces traditional mechanical linkages with an electronic actuation system using electromagnets and permanent magnets. The electromagnet assembly activates to retract the magnet assembly from the rail, eliminating complex mechanical linkages that are inefficient for high-speed elevators with larger airgaps, thereby reducing maintenance costs while maintaining braking reliability
Solution Approach 2:
The patent changes the actuation mechanism from mechanical to electromagnetic, allowing the system to effectively operate over larger airgaps characteristic of high-speed elevators. The electromagnet assembly generates magnetic fields that can act across the airgap without direct mechanical contact, adapting the system to high-speed elevator requirements
2Force
If the electromagnet assembly strongly attracts the magnet assembly for effective braking, then braking force is improved, but magnetic flux leakage increases reducing efficiency
Solution Approach 1:
The patent introduces a return biasing member as an intermediary element between the electromagnet assembly and the magnet assembly. This biasing member assists the electromagnet in retracting the magnet assembly from the rail by providing additional force, allowing the electromagnet to operate with lower current and reducing magnetic flux leakage while maintaining effective braking force
Solution Approach 2:
The patent segments the actuation function into two parts: the electromagnet assembly provides primary actuation force, while the return biasing member provides auxiliary force during retraction. This segmentation allows each component to operate more efficiently, reducing the overall energy consumption and magnetic flux leakage of the system
3Force
If the electromagnet assembly is positioned close to the hoistway rail for strong magnetic attraction, then braking effectiveness is improved, but the airgap cannot accommodate high-speed elevator float
Solution Approach 1:
The patent replaces direct mechanical contact or small-airgap magnetic systems with an electromagnetic actuation system that can effectively operate over larger airgaps. The electromagnet assembly generates magnetic fields that penetrate the larger airgap to attract the magnet assembly, accommodating the float characteristic of high-speed elevators while maintaining braking effectiveness
Solution Approach 2:
The patent extends the magnetic interaction into the airgap dimension by using electromagnets that can generate sufficient magnetic field strength across larger distances. The elongated block legs and core stub legs are positioned to maximize magnetic coupling across the airgap, allowing the system to adapt to varying airgap sizes in high-speed elevators
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 electronic actuator system provides efficient and reliable overspeed braking by minimizing magnetic flux leakage and maximizing magnetic attraction, enabling effective operation over larger airgaps, thus improving safety and reducing maintenance costs in high-speed elevators.
Implementation Method 1
an electromagnet assembly; and a first magnet assembly configured for being retracted from engagement with a hoistway rail depending on an energized state of the electromagnet assembly
Implementation Method 2
the first magnet assembly configured for being retracted into the system housing from engagement with the hoistway rail via the hoistway rail engagement aperture, when the electromagnet assembly, depending on its energized state, moves to engage the first magnet assembly
Implementation Method 3
a return biasing member is disposed between the system housing and the electromagnet assembly to bias into the system housing the electromagnet assembly and the first magnet assembly, which are stuck to each other via magnetism
Data Source
AI summary
An electronic actuator for an elevator safety brake system, the actuator having: an electromagnet assembly; and a first magnet assembly configured for being retracted from engagement with a rail depending on an energized state of the electromagnet assembly, the first magnet assembly including: blocks spaced apart from each other, respectively defining block bodies, and elongated block legs respectively extending aft from the block bodies; and a first magnet is disposed between the block bodies; wherein the electromagnet assembly includes: a core that defines: a core body extending between core ends that are spaced apart from each other; and core stub legs respectively extending forward from the core ends that are positioned adjacent to the elongated block legs when the first magnet assembly is retracted; and a coil winding wound about bobbins that are placed over the core body, the elongated block legs are longer than the core stub legs.