Elevator Rope Vibration Damping With Limited Displacement Amplification
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Solution Overview
Problem
Conventional vibration damping devices face instability issues due to nonlinear negative stiffness, which becomes excessively large at increased displacements, leading to ineffective vibration damping, especially in structures with large amplitudes, and are challenging to implement effectively at positions with high vibration amplitudes.
Innovation Solution
A vibration damping device incorporating a displacement amplifier and limiting members to control displacement amplification, ensuring the structure's displacement does not exceed a predetermined first displacement, thereby preventing instability and enhancing vibration control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If negative stiffness is used to amplify displacement for vibration damping, then vibration damping effect is improved, but instability occurs when displacement becomes large
Solution Approach 1:
The patent applies dynamics by making the stiffness characteristic variable rather than fixed. The displacement amplifier uses negative stiffness that dynamically adapts to displacement magnitude, providing stronger amplification at small displacements while automatically reducing amplification as displacement increases, thus preventing instability while maintaining effective vibration damping across different amplitude ranges.
Solution Approach 2:
The patent changes the stiffness parameter from a constant negative value to a variable parameter that depends on displacement magnitude. By making the negative stiffness value change with displacement (smaller negative stiffness at large displacements, larger negative stiffness at small displacements), the system maintains stability while preserving vibration damping effectiveness throughout the motion range.
2Device complexity
If damper is placed at position with small amplitude, then device complexity is reduced, but vibration damping effect becomes insufficient
Solution Approach 1:
The patent segments the vibration damping function into two distinct components: a displacement amplifier that uses negative stiffness to amplify the displacement signal, and a separate damper that dissipates energy. This segmentation allows the damper to be positioned at locations with smaller amplitudes (reducing device complexity) while the displacement amplifier ensures sufficient damping effect by amplifying the displacement before it reaches the damper.
Solution Approach 2:
The displacement amplifier acts as an intermediary between the vibrating structure and the damper. It takes the small displacement at the damper location and amplifies it, effectively transferring the vibration damping function to a position where the original amplitude is small, thus maintaining vibration damping effectiveness without requiring the damper to be positioned at high-amplitude locations.
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 solution effectively stabilizes vibration damping, preventing instability and enhancing the vibration control effect by ensuring the displacement amplifier operates within a stable range, even at large displacements, thus improving the damping performance across varying amplitudes.
Implementation Method 1
since negative stiffness obtained with an inverted pendulum or a permanent magnet has a property such that its stiffness value increases nonlinearly with an increase in displacement of a long structure
Implementation Method 2
a limiting member that controls displacement amplification performed by the displacement amplifier such that the displacement of the structure amplified by the displacement amplifier does not become greater than a first displacement
Implementation Method 3
a damper (which converts vibration energy into heat energy and dissipates the energy) disposed in a machine room located near an end of the elevator rope
Data Source
AI summary
An object of the present invention is to provide a vibration damping device including an instability preventing means, for efficiently suppressing amplification of vibration of a long structure, which is mechanically flexible, due to a resonance phenomenon. A vibration damping device (100) for reducing vibration of a long structure (1) includes a displacement amplifier (7) and limiting members (8). The displacement amplifier (7) is arranged along a given position in the longitudinal direction of the structure (1). The displacement amplifier (7) amplifies a displacement of the structure (1). The limiting members (8) control displacement amplification performed by the displacement amplifier (7) such that the displacement of the structure (1) amplified by the displacement amplifier (7) does not become greater than a first displacement, the first displacement being a displacement of the structure (1) by which the structure (1) is not allowed to return to the equilibrium position of the vibration.