Active Vibration Damper System for Multidirectional Crane Control
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Solution Overview
Problem
Existing vibration damper systems for cranes, particularly double-girder overhead traveling cranes, are inadequate in damping vibrations in multiple directions, leading to reduced productivity and increased costs due to structural instability caused by oscillations.
Innovation Solution
A vibration damper system with two active damper assemblies, each mounted on a bridge girder, featuring linear motors that move damper masses along parallel straight lines to counteract both linear and rotational movements, allowing independent damping of movement components and ensuring symmetrical mass distribution for effective control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single active vibration damper is placed centrally on the crane structure, then linear vibrations in the direction of trolley movement are damped, but rotational vibrations caused by side winds cannot be eliminated
Solution Approach 1:
The single central damper is segmented into two separate damper assemblies, each mounted on a different bridge girder. This segmentation allows each damper to independently address specific vibration components, with the first damper handling linear vibrations and the second damper handling rotational vibrations, thereby achieving comprehensive multi-directional vibration damping.
2Productivity
If the linear motor is mounted eccentrically on one bridge girder to dampen trolley movement vibrations, then linear vibration damping is achieved, but unwanted rotational movements are stimulated due to leverage effect
Solution Approach 1:
The system deliberately uses asymmetric mounting positions for the two linear motors on different bridge girders. The first linear motor is mounted at a first distance from the centerline, and the second linear motor is mounted at a second distance from the centerline. This asymmetric arrangement allows the motors to generate both linear damping forces and counteracting rotational moments, eliminating both linear and rotational vibrations simultaneously.
3Reliability
If passive vibration absorbers with high damper mass are used, then effective vibration absorption is achieved, but the mass required is very high (up to 60 tons)
Solution Approach 1:
The passive mechanical vibration absorption system is replaced with an active control system using linear motors. Instead of relying on large inertial masses to absorb vibrations passively, the system uses controllable electromagnetic forces from linear motors to actively counteract vibrations. This substitution dramatically reduces the required mass while maintaining or improving vibration damping effectiveness.
4Stability of the object's composition
If the crane portal is made more rigid to reduce vibration, then vibration reduction is achieved, but a lot of effort and material usage is required
Solution Approach 1:
The mechanical solution of increasing structural rigidity through additional materials is replaced with an active vibration control system. The linear motors mounted on the bridge girders generate forces that actively counteract vibrations, achieving stability enhancement without requiring additional structural materials or portal reinforcement.
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 system effectively dampens multidirectional vibrations, enhancing crane stability and productivity by independently controlling damping forces and torques, thereby reducing unwanted movements and maintaining structural balance.
Implementation Method 1
A linear motor that moves a damper mass is attached to the center of the bridge girder of the container bridge
Implementation Method 2
The vibration of the crane in the direction of movement of the trolley, which is excited by the movement of the trolley and is to be damped with the linear motor or the damper mass moved by this, is measured with an acceleration sensor
Implementation Method 3
The damper mass is coupled to the crane structure to be damped in such a way that it oscillates in the opposite direction to the crane structure
Data Source
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AI summary
The vibration system comprises an oscillatory structure (12) mounted with a sensor (20) for detection of two different components of motion relative to a reference system, an active damper assembly (22) having a damper mass (26) fastened to the motor (28), and an active damper assembly (24) having a damper mass fastened to the motor. A control unit generates control signals for controlling the motor based on the sensor signals, such that the damper masses carry out compensatory movements along straight/circular paths relative to the oscillatory structure. An independent claim is included for a method for damping multidirectional vibrations of vibrating structure, using a vibration system.