Piston Mounting Torque-Free Locking
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Solution Overview
Problem
Existing methods for mounting a piston onto a piston rod, such as threaded connections, face difficulties in field repairs due to high torque requirements and can cause shear forces leading to damage when using pins or bolts for simpler mounting methods.
Innovation Solution
A piston with a penetrating hole and internal thread, along with axial grooves on both the piston and piston rod, allows for torque-free locking using a securing means and locking ring, facilitating easy mounting and demounting without requiring significant torque or rotation-induced shear forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a threaded connection is used to mount the piston onto the piston rod, then the connection strength is improved, but the ease of repair deteriorates due to high torque requirements
Solution Approach 1:
The connection system is segmented into multiple functional elements: the threaded section provides initial mechanical engagement, while the separate locking element (nut or retaining ring) provides the locking function. This segmentation allows the mounting process to be divided into insertion and locking steps, reducing the torque required during initial assembly and enabling easier field repairs.
Solution Approach 2:
The piston rod is pre-equipped with a threaded section and the piston has a corresponding internally threaded hole before assembly. This preliminary preparation of threading allows for straightforward screw-together assembly without requiring complex alignment or high torque during the mounting process, facilitating easier field repairs.
2Ease of operation
If a pin or bolt is used to secure the piston, then the ease of operation is improved, but the reliability deteriorates due to shear forces causing damage
Solution Approach 1:
The invention merges the advantages of threaded connections (strength) with the simplicity of pin-based operation. The threaded section provides secure mechanical engagement while the locking element (nut or retaining ring) maintains the ease of operation for mounting and demounting, eliminating the need for pins or bolts that would be subject to damaging shear forces.
Data Source
Figure 1~2
Figure 3~8
AI summary
The present invention concerns an arrangement for the mounting of a piston (2) onto a piston rod (4) for a hydraulic or pneumatic piston-cylinder unit (1), which piston (2) is provided with a penetrating hole (7) with an internal thread (8) and a first axial groove (9), which groove (9) is intended to be aligned with a second axial groove (22) arranged in association with a section (21) of the piston rod (4) when the piston (2) is mounted onto the piston rod (4), and in that the grooves (9, 22) after the alignment form an indentation (26) intended to receive a securing means (28). The end (16) of the piston rod (4) comprises a peripheral opening (24) for a locking means (25) that prevents the securing means (28) from being displaced from the indentation (26). The invention concerns also a method for the mounting of a piston onto a piston rod.