Lifting Gear Torque Control for Vibration Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lifting gear systems, such as cranes, face challenges in safely lifting and setting down loads without causing vibrations or pendulum movements in the crane structure, which can lead to unsafe conditions and potential damage to the load.
Innovation Solution
A method for starting up a lifting mechanism that involves initially reducing the tightening torque for tensioning the lifting means and then increasing it, with a control device automatically limiting the torque to an initial maximum value greater than the load-free lifting resistance torque but less than the load lifting torque, and adjusting the torque based on the load acting on the lifting mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the lifting mechanism drive is operated with high tightening torque from the start, then the lifting process is faster and more productive, but vibrations and pendulum movements occur in the crane structure
Solution Approach 1:
The patent applies preliminary action by first tensioning the lifting means with reduced tightening torque before increasing to full torque. This preliminary phase prepares the system by gradually engaging the lifting means and reducing sudden structural shocks, thereby preventing vibrations and pendulum movements while still achieving efficient lifting.
Solution Approach 2:
The control device dynamically adjusts the tightening torque in two phases: initially limiting torque to prevent vibrations during tensioning, then increasing torque for efficient lifting. This dynamic adaptation of operating parameters resolves the contradiction between speed and structural stability.
2Object-affected harmful factors
If the lifting mechanism drive is operated with reduced tightening torque, then vibrations are minimized, but the lifting process takes longer
Solution Approach 1:
The patent uses preliminary action by first applying reduced torque to tension the lifting means and only after this initial phase completes does it increase to full torque. This ensures vibrations are minimized during the critical tensioning phase while maintaining productivity through subsequent high-torque operation.
Solution Approach 2:
The lifting process is divided into periodic phases: an initial phase with reduced torque for tensioning, followed by a second phase with increased torque for lifting. This periodic variation in operating conditions optimizes both structural safety and lifting efficiency.
3Object-affected harmful factors
If experienced operators manually control the lifting process, then vibrations can be reduced through gentle operation, but the operation becomes more complex and requires high skill
Solution Approach 1:
The control device automatically performs the function previously requiring skilled operator judgment. It self-regulates the tightening torque in two phases, eliminating the need for operator experience in timing and torque modulation, while achieving consistent vibration reduction.
Solution Approach 2:
The control device uses feedback from sensors detecting the tensioning state of the lifting means to automatically adjust torque. This closed-loop control replicates and standardizes the skilled operator's gentle operation approach, making it accessible to all operators regardless of experience level.
4Productivity
If the crane structure is abruptly tensioned during lifting, then the lifting process is faster, but strong vibrations occur in the structure
Solution Approach 1:
The patent applies preliminary action by first gradually tensioning the lifting means with reduced torque to prepare the crane structure, then proceeds to faster lifting once the structure is stabilized. This prevents abrupt tensioning and associated vibrations while maintaining overall lifting efficiency.
Solution Approach 2:
The control device provides beforehand cushioning by limiting tightening torque during the initial tensioning phase. This cushioning effect protects the crane structure from abrupt loads and vibrations, creating a stable foundation for subsequent faster lifting operations.
Data Source
AI summary
A lifting gear such as a crane having a lifting mechanism for lifting a load, a lifting mechanism drive for driving the lifting gear and a control device for controlling the lifting mechanism drive, as well as a method for starting up the lifting mechanism of such a lifting gear for gentle lifting of the load. In an initial phase for initial tensioning of the lifting means, the tightening torque of the lifting mechanism drive is automatically limited by the control device to an initial maximum torque that is only slightly greater than a load-free lifting resistance torque of the lifting mechanism, and then in a further phase for further tightening, the maximum torque increases in a load-induced manner and/or a rate of change of the drive speed of the lifting mechanism drive is limited to a maximum tightening acceleration.