Slewing Crane Jib Alignment via Local Wind Stress Measurement
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Solution Overview
Problem
Slewing cranes face instability and auto-rotation issues due to disrupted air inflow, which cannot be effectively addressed by determining wind direction and speed alone, leading to potential operational hazards.
Innovation Solution
Implementing measuring elements to record local wind stress values, calculating a preferred direction with minimal wind stress, and using a signal unit to automatically align the jib in this direction, with optional manual rotation or parking brake activation to maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wind direction and wind speed are measured alone, then the measurement system is simple, but the determination of minimal wind stress direction is inaccurate leading to auto-rotation
Solution Approach 1:
The patent segments the wind stress measurement into multiple local measurement points on the jib structure. By placing measuring elements at different locations (e.g., leading edge, trailing edge, top, bottom), the system captures localized wind stress data that reveals the actual minimal stress direction, which may differ from the overall wind direction due to disrupted air inflow patterns.
Solution Approach 2:
The patent introduces measuring elements (such as strain gauges or stress sensors) as intermediaries between the wind load and the control system. These elements directly measure the mechanical stress state of the jib structure, providing accurate real-time data about the actual wind stress direction without requiring complex computational models to infer it from wind speed and direction alone.
2Stability of the object's composition
If the jib is locked in the wind direction, then the alignment is simple, but the stability is reduced due to disrupted air inflow causing auto-rotation
Solution Approach 1:
The patent implements a feedback control system where local wind stress measurements continuously inform the adjustment of the jib's orientation. The control unit monitors the measured stress values and automatically adjusts the jib angle to maintain alignment with the minimal wind stress direction, compensating for disrupted air inflow patterns and preventing auto-rotation while maintaining operational simplicity.
Solution Approach 2:
The patent transitions from a static alignment approach (fixed wind direction locking) to a dynamic alignment system that continuously adapts the jib orientation based on real-time local wind stress measurements. This dynamic adjustment allows the system to respond to changing wind conditions and disrupted air inflow patterns, maintaining optimal stability without requiring manual intervention.
3Speed
If complex models are used to calculate wind stress direction, then the theoretical accuracy is high, but the real-time response is slow and cannot prevent auto-rotation
Solution Approach 1:
The patent replaces complex computational mechanical/wind models with direct mechanical measurement using stress sensors or strain gauges mounted on the jib structure. This substitution provides immediate real-time data about the actual wind stress direction without requiring computational processing, enabling fast response to prevent auto-rotation while maintaining high accuracy through direct physical measurement.
Data Source
Figure 1
Figure 2a~2b
AI summary
Slewing crane (1) with a vertically running vertical axis (5), a boom (8) projecting from the vertical axis (5), a drive for rotating the boom (8) about the vertical axis (5), a status monitoring system which determines a wind load, in particular internal forces, stresses, strains, shear forces, tilting moments and torsional moments of the slewing crane (1), and a processing unit which calculates a preferred direction for fixing the boom (8) from the wind load. Also disclosed is a method for aligning a slewing crane (1) of this type. To improve the alignment of the boom (8) on slewing cranes (1) which have been shut down, it is proposed that the slewing crane comprises measurement elements (14, 16) for receiving local measured values of the wind load.