Crane Winch Control via Variable Displacement Motor
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Solution Overview
Problem
The existing winch system for cranes faces difficulties in improving operability, particularly when lifting off the ground, as it struggles to effectively manage the transition from zero lifting load to hoisting, leading to inefficient high-speed mode switching and reduced performance.
Innovation Solution
A crane system equipped with a high/low speed hydraulic motor and a control unit that switches between high and low speed modes based on load and tension thresholds, using a high/low speed switching valve and control cylinder to optimize winch operation, allowing for efficient high-speed hoisting at the initial stage of lifting off the ground and transitioning to low-speed mode as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a variable displacement motor is used to achieve high-speed lowering, then the wire rope can be lowered at high speed, but the system becomes complex and difficult to control during the transition from zero lifting load to hoisting
Solution Approach 1:
The patent applies dynamics by making the motor displacement variable rather than fixed. The variable displacement motor automatically adjusts its displacement based on the detected lifting load, enabling high-speed operation when load is small and automatic transition to low-speed operation when load increases, eliminating the need for complex manual mode switching while maintaining operational simplicity
Solution Approach 2:
The patent changes the parameter of motor displacement dynamically based on the lifting load. By detecting the load and automatically adjusting the motor displacement parameter, the system achieves high-speed lowering when appropriate while avoiding the complexity of manual intervention, and automatically transitions to low-speed mode when load conditions change
2Productivity
If high-speed mode is used at the initial stage of lifting off the ground, then lifting efficiency is improved, but unstable control occurs due to load and tension fluctuations
Solution Approach 1:
The patent implements feedback control by continuously detecting the lifting load and wire rope tension, then automatically adjusting the motor displacement based on these feedback signals. This closed-loop control enables high-speed operation during stable phases while automatically reducing speed when fluctuations are detected, maintaining both productivity and reliability without operator intervention
Solution Approach 2:
The system performs self-service by automatically detecting load conditions and adjusting its own operating parameters. The variable displacement motor self-regulates its displacement based on detected conditions, enabling the system to maintain optimal performance and stability automatically without requiring external control input from the operator
3Ease of operation
If manual mode switching is required between high and low speed modes, then precise control is possible, but operability is reduced due to frequent manual intervention
Solution Approach 1:
The system achieves self-service by automatically detecting lifting load conditions and autonomously switching between high and low speed modes. This eliminates the need for manual mode switching while maintaining precise control based on actual load conditions, significantly improving ease of operation without sacrificing automation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances crane operability by enabling high-speed hoisting at the initial stage of lifting off the ground and stable mode switching, preventing excessive pressure and frequent mode changes, thus improving overall lifting efficiency and reducing the risk of unstable control due to load and tension fluctuations.
Implementation Method 1
a high/low speed switching valve 33 capable of switching between a first state where hydraulic oil is supplied from the high/low speed switching valve 33 to the control cylinder 24 and a second state where supply of the hydraulic oil from the high/low speed switching valve 33 to the control cylinder 24 is interrupted
Data Source
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AI summary
The present invention is provided with: a manipulation unit; a winch device that operates with an actuation mode of either a high speed mode or a low speed mode on the basis of manipulation of the manipulation unit, and winds in or reels out a wire rope to which a hook is fixed; a selection unit for an operator to select either the high speed mode or the low speed mode; a load calculation unit for calculating a suspended load; a tension calculation unit for calculating the tension of the wire rope; and a control unit for controlling the actuation of the winch device. If the mode selected by the selection unit is the high speed mode, the manipulation unit is manipulated from a neutral state to a non-neutral state, and the suspended load is smaller than a load threshold and the tension is smaller than a tension threshold, the control unit controls the winch device so as to operate in the high speed mode. Through this, a winch system of a mobile crane having excellent operability is provided.