Hydraulic Crane Control for Vertical Load Lowering
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Solution Overview
Problem
Existing hydraulic crane overload protection systems require operators to move loads closer to the crane column after an overload is detected, limiting the crane's lifting capacity and efficiency in reducing the lifting radius.
Innovation Solution
An electronic control system in a hydraulic crane that prevents crane boom movements from increasing the horizontal distance between the load suspension point and the vertical axis of rotation when the lifting moment reaches a predetermined limit, allowing movements that maintain or reduce this distance, enabling direct vertical lowering of the load and switching between operating modes to optimize lifting capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the overload protection system blocks all crane boom movements that increase the lifting moment when the limit is reached, then the lifting moment is kept within safe limits, but the operator cannot lower the load vertically and must move it closer to the column, reducing operational efficiency
Solution Approach 1:
The control system dynamically adjusts which movements are permitted based on the current lifting moment relative to the maximum value. When the lifting moment is below the maximum, all movements are allowed. When it reaches the maximum, the system dynamically blocks only those movements that would increase the lifting moment, while permitting movements that reduce it, enabling efficient load placement without compromising safety.
Solution Approach 2:
The system changes the control parameters (permitted movement directions) based on the lifting moment parameter. By monitoring the lifting moment and adjusting the allowed movement envelope accordingly, the system enables vertical lowering movements when appropriate while preventing movements that would exceed the maximum lifting moment, thus resolving the contradiction between safety and efficiency.
2Reliability
If the electronic control device prevents all crane boom movements that increase horizontal distance when lifting moment reaches limit value, then the lifting moment is controlled within safe limits, but the crane operator cannot utilize the full lifting capacity to move loads horizontally
Solution Approach 1:
The control system modifies the operational parameters (allowed boom movements) based on the lifting moment parameter. When the lifting moment is below the maximum value, the crane operates with full adaptability allowing all movements. When the lifting moment reaches the maximum, the system adaptively adjusts permitted movements to prevent increases in horizontal distance while allowing vertical lowering, thus maintaining both safety and operational versatility.
Data Source
AI summary
A hydraulic crane comprising: —a rotatable column (7); —a crane boom system (10) comprising two or more liftable and lowerable crane booms (11, 13); and —an electronic control device (25), which is configured to prevent an execution of crane boom movements that would make the lifting moment of the crane exceed the maximum allowed lifting moment of the crane, and to continuously establish position information as to the prevailing position of the load suspension point (P) of the crane boom system. When the lifting moment of the crane has reached a limit value at a given level below the maximum allowed lifting moment, the electronic control device is configured to prevent the execution of any combination of crane boom movements that would increase the horizontal distance between the load suspension point and said vertical axis of rotation and at the same time allow the execution of any combination of crane boom movements that keeps said horizontal distance unchanged or reduces said horizontal distance.