Marine Knuckle Boom Crane Cable Control System
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Solution Overview
Problem
Conventional hydraulic cylinders in knuckle boom cranes limit the reach and maximum load capacity, especially when scaling up to lift heavier loads, restricting the design options for the main boom and jib dimensions.
Innovation Solution
A tensioning member and curved extension guide system, combined with a luffing cable and winch, allow for precise control of the jib and main boom positions, enabling a wider range of configurations without the limitations of hydraulic cylinders, including smaller cross-sections and varied dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If hydraulic cylinders are used to control the main boom and jib, then the crane can operate for smaller loads, but the reach and maximum load capacity are limited when scaling up
Solution Approach 1:
The patent replaces the hydraulic cylinder system with a cable-based mechanical system consisting of a luffing cable for main boom control and a tensioning cable for jib control. This substitution allows for greater load capacity and reach by utilizing the mechanical advantage of cable winches instead of hydraulic actuators, enabling the crane to handle heavier loads while maintaining operational control.
Solution Approach 2:
The invention changes the control parameters from hydraulic pressure and piston displacement to cable length and winch rotation. By controlling the length of the luffing cable and tensioning cable through winch mechanisms, the system achieves variable boom positions and angles, providing adaptability across different load ranges and operational scenarios without the size constraints of hydraulic systems.
2Adaptability or versatility
If hydraulic cylinders are used for boom control, then the structure can be simpler, but the positioning flexibility and range of configurations are restricted
Solution Approach 1:
The control system is segmented into independent cable mechanisms: a luffing cable for main boom angle control and a tensioning cable for jib angle control. Each cable is managed by its own winch mechanism, allowing independent adjustment of boom and jib positions. This segmentation provides extensive positioning flexibility while keeping each individual control mechanism relatively simple and modular.
3Volume of moving object
If the boom cross-section is reduced for compact storage, then the crane can be more maneuverable, but the load bearing capacity decreases
Solution Approach 1:
The patent employs dynamic cable tensioning and winch control to compensate for the reduced structural size. By actively adjusting cable lengths and tensions during operation, the system maintains adequate load bearing capacity even with smaller boom cross-sections. The dynamic control allows the crane to maneuver compactly while achieving sufficient strength through mechanical advantage rather than purely structural bulk.
Data Source
AI summary
A marine knuckle boom crane includes a crane housing which is rotational relative to a pedestal about a vertical rotation axis and a knuckle boom assembly attached to the crane housing. The knuckle boom assembly includes a main boom, the inner end of which is connected pivotably about a first horizontal pivot axis to the crane housing; and a jib, the inner end of which is connected pivotably about a second horizontal pivot axis to the outer end of the main boom, wherein the jib is pivotable at least between an extended position in which the tip extends mainly forward from the main boom, and a folded position in which the jib is folded back, essentially parallel along the main boom. In order to position the jib with respect to the main boom, a tensioning member is provided extending between the crane housing and a guide structure connected to the jib.