Trash Rake Gripper Cable Synchronization
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Solution Overview
Problem
Conventional trash rake cleaners rely on hydraulic systems, which are environmentally harmful and maintenance-intensive, and require multiple cables and drives for opening and closing the gripper, leading to complex control mechanisms and limited operational depth.
Innovation Solution
A gripper device using a hoisting system with two cables attached to the gripper arm at specific points of engagement on either side of the rotation axis, allowing for simultaneous raising and lowering, and opening and closing without separate hydraulic systems, utilizing a controller with internal slippage coupling for synchronized operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydraulic system is used to open and close the gripper, then the gripper can be operated reliably, but the system becomes environmentally harmful and maintenance-intensive
Solution Approach 1:
The patent removes the hydraulic system entirely from the gripper mechanism, extracting the harmful fluid-based actuation and replacing it with a mechanical cable-driven system. This eliminates environmental contamination risks while maintaining reliable gripper operation through pure mechanical means.
Solution Approach 2:
The patent replaces the hydraulic mechanical system with a cable-based mechanical system. Instead of using hydraulic fluid pressure to actuate the gripper, the invention uses tensioned cables connected to drum mechanisms that convert rotational motion into linear cable movement, thereby opening and closing the gripper arms through purely mechanical action.
2Ease of operation
If separate cables and drives are provided for raising/lowering and opening/closing the gripper, then each function can be controlled independently, but the device complexity increases
Solution Approach 1:
The patent combines the functions of gripper actuation and position control into a single integrated cable system. By strategically positioning the cable attachment points on the gripper arms, the system achieves both opening/closing and raising/lowering through coordinated cable tension changes, eliminating the need for separate drive mechanisms for each function.
Solution Approach 2:
The cable system is designed to perform multiple functions simultaneously. The same cables that control gripper opening and closing also control the raising and lowering of the gripper assembly, making the cable system universal and multi-functional rather than requiring dedicated mechanisms for each motion type.
3Reliability
If multiple cables with drum and drive are provided for raising and lowering a heavy gripper, then the gripper can be supported reliably, but the weight and complexity of the system increase
Solution Approach 1:
The patent merges the support function with the actuation function in the cable system. The same cables that provide upward force to support the gripper weight also provide the differential tension needed for opening and closing operations, eliminating redundant support mechanisms and reducing overall system weight.
4Ease of operation
If conventional cable systems are used, then the gripper can be operated at shallow depths, but operation at greater depths is limited
Solution Approach 1:
The patent employs asymmetric cable routing and attachment point positioning to create inherent mechanical advantages that compensate for cable slack and tension differences. By strategically placing attachment points at specific locations on the gripper arms, the system creates geometric relationships that maintain reliable control even when cable tensions are not perfectly synchronized, enabling operation at greater depths.
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 eliminates the need for hydraulics, reduces the number of drives required, simplifies control, and enables operation at greater depths, ensuring the gripper remains in the desired position despite asynchronous cable tension, and complies with safety standards for explosive environments.
Implementation Method 1
the moment arm of the tensioning force in the first cable relative to the rotation axis is greater than the moment arm of the tensioning force in the second cable relative to the rotation axis, and in the closed end position the moment arm of the tensioning force in the first cable relative to the rotation axis is smaller than the moment arm of the tensioning force in the second cable relative to the rotation axis
Data Source
AI summary
A gripper device comprises a gripper with a gripper arm rotatable around a rotation axis such that the gripper is movable between an open end position and a closed end position, and a hoisting device connected to the gripper and comprising a first cable and a second cable which are each connected with their one outer end to the gripper and are each connected with their other outer end to respectively a first and second hoisting means for raising and lowering the gripper with the cables, wherein each hoisting means is, driven by a separate drive, wherein a controller transmits the same control signal to both drives for the purpose of raising or lowering the gripper, and each drive comprises a motor with internal slippage or a slippage coupling so that synchronous running of the hoisting means is automatically realized.