Chain Hoist Variable-Speed Control for Resonance Prevention
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Solution Overview
Problem
Chain hoists experience resonance-induced vibrations due to the polygon phenomenon, which can lead to unsafe swinging and bouncing of loads, posing risks during lifting and lowering operations.
Innovation Solution
A control system that determines the onset of resonance by analyzing force signals, applies high-pass filtering, and adjusts the chain wheel's rotation speed using a correction term to avoid resonance without requiring additional damping mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the chain wheel rotates at constant angular speed, then the motor operates efficiently, but resonance occurs in the chain causing dangerous vibrations
Solution Approach 1:
The patent applies dynamics by transitioning from constant angular speed rotation to variable speed rotation. The control unit dynamically adjusts the motor speed based on real-time chain force measurements, allowing the system to adapt to resonance conditions and eliminate vibrations while maintaining efficient operation.
Solution Approach 2:
The patent implements feedback control by continuously measuring chain force with a sensor, comparing it against reference values, and using the deviation signal to adjust motor speed. This closed-loop feedback mechanism enables the system to detect resonance conditions and automatically correct them by modifying the rotation speed.
2Reliability
If damping mechanisms are added to reduce vibrations, then load stability improves, but device complexity increases
Solution Approach 1:
The patent replaces mechanical damping mechanisms with an electronic control system. Instead of adding physical dampers or mechanical shock absorbers to the chain hoist, the invention uses a control unit with sensors and motor speed adjustment to eliminate vibrations, thereby maintaining load stability without increasing mechanical complexity.
Solution Approach 2:
The patent applies parameter changes by modifying the motor speed parameter dynamically rather than adding physical damping components. The control unit adjusts the speed parameter based on chain force measurements, achieving vibration reduction through parameter optimization instead of structural modification.
Data Source
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AI summary
A method comprising: detecting the start of resonance when the chain hoist moves a load, determining a new speed for the rotation of the chain wheel of the chain hoist to avoid resonance, and controlling the chain hoist to use the new speed.