Piston Ring Damping Structure for Precise Cylinder End Cushioning
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Solution Overview
Problem
Existing end position damping solutions for work cylinders face challenges such as high constructive effort, low robustness, large hysteresis due to hydraulic inertia, and require precise preload adjustment, which limits their applicability and ease of manufacturing.
Innovation Solution
The solution involves an end layer-damped work cylinder with a piston unit that includes a piston ring with a radial outer coat area having an all-around inner ring groove, and a piston ring limiter to define the piston ring's preload situation, allowing for precise control of damping characteristics and path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If controlled hydraulic throttles are used in the inlets and outlets, then the flow rate of the working cylinder can be restricted, but the design complexity increases and robustness decreases
Solution Approach 1:
The patent extracts the damping function from complex hydraulic control systems and implements it directly through the piston unit's geometric design. The piston unit incorporates a damping zone with restricted flow passages that provide end-position damping without requiring external electronic control systems or additional hydraulic throttles, thereby reducing design complexity while maintaining flow rate control.
Solution Approach 2:
The piston unit serves multiple functions simultaneously: it seals the working chambers, transmits force, and provides end-position damping through its integrated damping zone. The damping effect is generated automatically by the piston's own movement through the restricted flow passages, eliminating the need for external control systems and reducing overall device complexity.
2Speed
If controlled hydraulic throttles are used in the inlets and outlets, then the flow rate of the working cylinder can be restricted, but operational reliability and robustness decrease
Solution Approach 1:
The patent removes the dependency on external electronic control systems and hydraulic throttles by integrating the damping function directly into the piston unit's structure. The damping zone with restricted flow passages provides inherent damping that is insensitive to hydraulic inertia and system dynamics, thereby improving operational reliability and robustness.
Solution Approach 2:
The piston unit incorporates a damping zone that provides predetermined end-position damping through its geometric design. The restricted flow passages create a cushioning effect before the piston reaches the end positions, reducing impact forces and improving reliability without requiring active control or adjustment during operation.
3Reliability
If a bottom-side chamber with mandrel is used for end-position damping, then damping effectiveness is achieved, but space requirements increase
Solution Approach 1:
The patent merges the damping function with the piston unit itself by integrating the damping zone directly into the piston's structure. The piston unit combines sealing, force transmission, and damping functions in a single component, eliminating the need for separate bottom-side chambers and mandrels, thereby reducing space requirements while maintaining damping effectiveness.
Solution Approach 2:
The damping zone is nested within the piston unit's structure, with the restricted flow passages integrated into the piston's geometry. The damping function is embedded within the existing piston components, allowing the damping mechanism to occupy minimal space while maintaining effectiveness.
4Manufacturing precision
If progressive throttling via variable annular gap of piston ring is used, then damping control is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent achieves damping control through geometric parameters of the damping zone and restricted flow passages rather than relying on precise preload adjustment of piston rings. The damping characteristics are determined by the dimensions and configuration of the damping zone, which can be manufactured using standard machining processes without requiring high-precision preload adjustment.
Solution Approach 2:
The patent replaces the complex, precision-dependent piston ring preload adjustment mechanism with a simpler damping zone design that uses standard machining tolerances. This approach reduces manufacturing complexity and cost while achieving reliable damping control through geometric design rather than precision adjustment.
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 design achieves high precision and adjustability of damping characteristics, is robust and safe, has low wear, and is easy and inexpensive to manufacture, while avoiding undefined starting points of damping and ensuring precise axial starting positions.
Implementation Method 1
the piston unit is designed to enclose a volume of damping pressure medium in a damping zone space during an inward movement towards the end position
Implementation Method 2
designed to restrict the spring travel of the piston ring in a relaxation direction and to fix the piston ring in a preload position
Data Source
Figure 1
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Figure 4~5
AI summary
The invention relates to an end-position damped working cylinder which has a damping zone in at least one end region, wherein a pressure medium connection is assigned to the damping zone and is axially spaced from an axial boundary of the cylinder interior, wherein a piston unit comprises a piston body, a resiliently designed piston ring with a piston ring gap and a piston ring limiter, wherein the piston unit is configured to axially pass over the pressure medium connection with the piston ring during a retraction movement into the damping zone and to enclose a damping pressure medium volume in a damping zone space in the damping zone and wherein an overpressure of the damping pressure medium volume is present relative to the pressure medium connection and the piston ring gap is configured for a throttled outflow of the damping pressure medium volume, and wherein the piston ring limiter is configuredto limit the spring travel of the piston ring outside the damping zone in a relaxation direction and to fix the piston ring in a preload position.