Eccentric Piston Rod Cylinder Torque Decoupling
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Solution Overview
Problem
Existing cylinder/piston assemblies with eccentric piston rods suffer from wear and leaks due to transverse forces when external torque is applied, and internal position measuring systems require large diameters and are sensitive to external forces.
Innovation Solution
A cylindrical element anchored on the end pieces and extending parallel to the piston rod provides torque support and integrates an internal position measuring system, allowing the piston rod to be rotatably mounted, reducing torque transmission and enabling smaller diameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If an eccentric piston rod is used to provide anti-rotation action, then anti-rotation capability is improved, but transverse forces act on the mounting causing wear and leaks
Solution Approach 1:
The anti-rotation function is segmented between two independent elements: the eccentric piston rod and the parallel cylindrical element. Each element contributes to torque support independently, distributing the mechanical stress and preventing excessive wear on any single mounting point while maintaining effective anti-rotation capability.
2Measurement precision
If internal position measuring systems are integrated in the piston rod, then position measurement is achieved, but the piston rod diameter must be enlarged
Solution Approach 1:
The cylindrical element serves as an intermediary structure that carries the position measuring system independently of the piston rod. This mediator approach allows the measuring system to be housed in the cylindrical element's bore rather than requiring the piston rod to be enlarged, thus achieving position measurement without increasing piston rod diameter.
3Device complexity
If the piston rod is rigidly connected to the piston, then structural simplicity is achieved, but torque is transmitted from piston rod to piston causing non-uniform force distribution
Solution Approach 1:
The torque transmission function is extracted from the piston rod-piston connection by introducing a rotatable mounting. This allows the piston rod to rotate independently on the piston, separating the force transmission function from the torque transmission function, thereby achieving uniform force distribution while maintaining structural simplicity through the use of a straightforward rotatable joint.
Data Source
AI summary
In a cylinder/piston assembly including a hydraulic cylinder and a piston which is sealingly mounted and longitudinally movable within the hydraulic cylinder and which, at least on one side, bears a piston rod, wherein the hydraulic cylinder has a cylinder barrel of circular cross section which is closed at both sides by in each case one end piece, and the piston rod extends along an axis that is eccentric with respect to the cylinder barrel, a cylindrical element is provided which is anchored on the two end pieces and which extends through the piston along a second axis which is eccentric with respect to the cylinder barrel and parallel to the first axis.