Hoist Drive Torque Control for Stable Brake Release
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Solution Overview
Problem
Existing hoist systems, such as cranes, face challenges in smoothly releasing the hoist brake without causing unwanted load movements due to the abrupt transfer of load from the brake to the drive, leading to instabilities and pendulum movements, especially in sensitive structures.
Innovation Solution
Adapting the starting torque to the individual load situation by using a load detection device to set the lifting force provided by the hoist drive to match the current load, including net load, load hook weight, and hoist rope weight, allowing for a smoother start by varying the starting torque based on the load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a predetermined starting torque is generated by the hoist drive against the engaged brake before releasing the brake, then the hoist drive provides a lifting force to prevent significant instabilities, but the load still moves slightly upwards or downwards causing unwanted oscillations and pendulum movements
Solution Approach 1:
The patent applies dynamics by making the starting torque variable rather than fixed. The control system continuously adapts the starting torque based on detected load conditions, allowing the torque to dynamically match the actual load requirements during brake release, thereby eliminating oscillations while maintaining stability
Solution Approach 2:
The patent implements feedback by using a load detection device to monitor the actual load and feed this information back to the control system. The control system then adjusts the starting torque based on this feedback, creating a closed-loop control that ensures the lifting force precisely matches the load, preventing unwanted movements
2Productivity
If the hoist brake is released abruptly to take over the suspended load, then the brake release is quick and simple, but significant instabilities and dynamic pendulum movements occur
Solution Approach 1:
The patent applies preliminary action by building up the starting torque gradually before the brake is released. The control system prepares the hoist drive by incrementally increasing torque to match the load requirements before brake release, ensuring that when the brake is released, the load is already supported by the appropriate lifting force, preventing instabilities
Solution Approach 2:
The patent makes the brake release process dynamic by continuously adjusting the starting torque based on real-time load detection. Rather than a fixed torque value, the system adapts the torque dynamically during the brake release process, allowing quick release while maintaining load stability through continuous control adjustments
Data Source
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AI summary
The present invention relates to a lifting gear, for example in the form of a crane such as a rotary tower crane (1), having a lifting mechanism (8), which comprises a lifting cable (6) running from a drum (17) which can be driven by a lifting mechanism drive (10), and a lifting mechanism brake (9) for holding the lifting cable in a braked position. The invention also relates to a method for starting up the lifting mechanism of such a lifting gear from the braked position in which the lifting mechanism brake holds a lifting load, wherein a starting moment is built up against the engaged lifting mechanism brake by a lifting mechanism drive, and the lifting mechanism brake is released when or after the starting moment is reached. When the lifting mechanism brake is engaged, the current lifting load is sensed by means of a load-sensing device (11), and the starting moment is set by the lifting mechanism controller using the sensed current lifting load such that the lifting force provided by the starting moment of the lifting mechanism corresponds to the sensed current lifting load.