Crane Load Error Detection via Torque and Tension Comparison
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Solution Overview
Problem
Conventional cranes lack the ability to quickly recognize errors in work information and the number of turns set in the safety apparatus, leading to potential operational hazards due to incorrect settings.
Innovation Solution
A crane system that calculates tensions of wire ropes from output torques of hydraulic winches and winding radii, estimates suspension loads based on set values, and compares these with actual loads calculated from hydraulic thrust and boom attitudes to determine erroneous settings, informing operators of any discrepancies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the safety apparatus stores rated load characteristics and working limit based on set number of turns, then the crane can prevent overloading and falling, but the system cannot detect erroneous settings of the number of turns
Solution Approach 1:
The system calculates the actual number of turns around the sheave using the relationship between wire rope tension (obtained from hydraulic pressure sensors) and hydraulic motor output torque, then compares this calculated value with the set number of turns stored in the safety apparatus. When a discrepancy is detected, the system outputs an alarm signal to notify the operator of the erroneous setting.
Solution Approach 2:
The patent replaces direct mechanical measurement of the number of turns with a calculation-based approach using the formula: number of turns = (hydraulic motor output torque × winding radius) / (wire rope tension × sheave radius). This substitution allows for indirect detection of the number of turns through force and motion relationships.
2Reliability
If the crane operates based on set work content and number of turns, then safety is maintained, but errors in setting go unrecognized
Solution Approach 1:
The system continuously monitors the actual number of turns by calculating it from real-time hydraulic pressure and motor torque data, then feeds this information back to compare with the preset value. This closed-loop feedback mechanism enables automatic detection of setting errors without interfering with normal crane operations.
Solution Approach 2:
The patent introduces an intermediary calculation system that derives the number of turns indirectly through the relationship between wire rope tension, hydraulic motor torque, and sheave geometry. This intermediary approach allows error detection without requiring direct mechanical sensing of turn count.
3Device complexity
If no error detection system is provided, then the system remains simple, but erroneous settings cannot be identified
Solution Approach 1:
The error detection system utilizes existing sensors (hydraulic pressure sensors and motor torque sensors) to calculate and compare the actual number of turns with the set value. By leveraging already-present measurement components, the system achieves error detection capability without requiring additional complex hardware.
Solution Approach 2:
The system uses its own operational parameters (hydraulic pressure, motor torque, wire rope tension) to self-diagnose whether the set number of turns matches the actual number of turns. This self-service approach enables error detection using data already collected during normal operation.
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
Enables operators to swiftly identify and correct erroneous settings, ensuring safe and efficient crane operations by providing a clear indication of errors in work information and turn settings, thus enhancing safety and operational reliability.
Implementation Method 1
tensions of the wire ropes are calculated from output torques of the plurality of hydraulic winches and winding radiuses of the wire ropes wound around the plurality of hydraulic winches
Implementation Method 2
an actual suspension load is calculated from a thrust of the hydraulic cylinder and a shape and attitude of the boom
Data Source
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AI summary
Provided is a crane capable of allowing an operator to recognize an error in work information or in a number of windings set in a safety device. A main tension of a main wire rope is calculated from a main output torque of a main winch, a sub output torque of a sub winch , a main drum winding radius of the main winch, and a sub drum winding radius of the sub winch. An estimated hanging load, which is calculated from the main tension, a sub tension of a sub wire rope and the number of windings of the wire rope set in a safety device, is compared with an actual hanging load calculated from fluctuating thrust force and boom information. Thus, the suitability of a work kind or a winding number set in the safety device is determined.