Hydraulic Motor Cable Drum for Load Position Compensation
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Solution Overview
Problem
Existing compensating devices for maintaining target positions of loads handled by cable hoists are inefficient due to large hydraulic components, high fluid requirements, and increased friction, making them unsuitable for timely and accurate positional correction, especially in dynamic environments like harbor crane systems or transport ships exposed to waves.
Innovation Solution
A compensating device with a hydraulic motor drive system featuring two separate pressure chambers with different pressure levels, one in high-pressure mode and the other connected to a low-pressure accumulator, allowing for efficient torque and fluid management, reducing wear and enabling direct control of the cable winch for precise positional adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydraulic working cylinder with guide roller is used to compensate for load position deviations, then the load position can be maintained, but the device occupies large installation space and requires large quantities of operating fluid
Solution Approach 1:
The patent replaces the conventional hydraulic working cylinder with a guide roller with a hydraulic motor-driven cable drum. The hydraulic motor (14) winds and unwinds the cable (13) to adjust the effective cable length, thereby compensating for load position deviations. This substitution eliminates the need for a large-stroke hydraulic cylinder and guide roller assembly, significantly reducing installation space while maintaining the load position maintenance function.
Solution Approach 2:
The patent uses a hydraulic motor (14) to drive the cable drum, replacing the conventional hydraulic cylinder actuation. The hydraulic motor converts hydraulic energy into rotational motion to wind/unwind the cable, achieving the same compensation function with reduced spatial requirements and improved fluid efficiency.
2Adaptability or versatility
If a hydraulic working cylinder with long stroke is used to compensate for large position deviations, then the compensation range is sufficient, but the hydraulic pump and circuit require large quantities of operating fluid reducing overall efficiency
Solution Approach 1:
The patent replaces the linear motion of a long-stroke hydraulic cylinder with rotational motion of a hydraulic motor driving a cable drum. The hydraulic motor winds and unwinds the cable to achieve the same compensation range without requiring a long linear stroke, thereby reducing the volume of hydraulic fluid needed and improving system efficiency.
Solution Approach 2:
The patent changes the motion parameter from linear displacement (hydraulic cylinder stroke) to rotational displacement (hydraulic motor rotation). This parameter change allows the same compensation function to be achieved with reduced hydraulic fluid volume, as the cable can be wound/unwound through multiple rotations of the drum rather than requiring a single long linear extension.
3Ease of operation
If the cable is deflected around the guide roller of the working cylinder for compensation, then the effective cable length can be adjusted, but the cable is subject to increased frictional wear
Solution Approach 1:
The patent eliminates the guide roller that causes cable deflection and frictional wear by using a hydraulic motor-driven cable drum. The cable is wound directly on the drum, maintaining adjustment capability without the harmful deflection and associated wear that occurs when the cable bends around a guide roller.
4Reliability
If a conventional hydraulic cylinder compensating device is used, then the load position can be maintained, but the compensation operation requires considerable time due to large fluid volumes
Solution Approach 1:
The patent replaces the slow-responding hydraulic cylinder with a hydraulic motor-driven cable drum system. The hydraulic motor can rapidly wind and unwind the cable, providing faster compensation response times while maintaining the same load position maintenance reliability, as rotational actuation is generally faster than linear cylinder extension/retraction for equivalent displacement.
Data Source
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AI summary
The invention relates to a compensating device (200) for maintaining specifiable target positions of a load (206) which can be handled using a cable hoist (202) and which is attached to a cable (216) of the cable hoist, the respective specifiable target position of the load changing unintentionally to an actual position deviating from the target position. The compensating device consists of at least one sensor device (240, 242) for detecting the respective actual position of the load (206); a rotational drive (226, 228, 230) for specifying a cable length of the cable hoist (202); and at least one controller (244) which changes the cable length after the respective actual position has been detected until the load (206) re-assumes its target position. The respective drive (226, 228, 230) can be controlled at least partly by at least one hydraulic motor (226, 228, 230) with opposite rotational directions, said motor being connected to an actuating device (246) which has at least two separate pressure chambers (250, 252) with pressure levels that differ during operation, thereby forming a drive section (248) for the respective hydraulic motor (226, 228, 230), and which can be actuated by the controller (244).