Hydraulic Cylinder Seal Notches and Hinge for Pressure Relief
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Solution Overview
Problem
Existing seal systems for reciprocating rods in hydraulic cylinders face challenges in preventing fluid leakage and pressure buildup, with current designs often leading to sticking issues and inadequate extrusion resistance.
Innovation Solution
The proposed seal system includes a buffer seal with a dynamic and static lip configuration featuring radially extending notches to prevent sticking and a back-up ring for enhanced extrusion resistance, and a rod seal with an elastomeric annular seal body and symmetrical dynamic and static lips to manage pressure and fluid flow, both integrated with venting mechanisms to alleviate pressure buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional seal system with buffer seal, rod seal, and wiper seal is used, then sealing against the reciprocating rod is achieved, but pressure buildup occurs between the seals causing sticking issues
Solution Approach 1:
The seal system is divided into multiple functional segments: buffer seal with pressure relief features, rod seal with venting mechanism, and wiper seal. Each segment handles specific aspects of sealing and pressure management, preventing overall pressure buildup while maintaining sealing effectiveness.
Solution Approach 2:
The buffer seal acts as an intermediary element between the rod seal and wiper seal, providing pressure relief through its hinge portion and notches. This intermediary structure prevents pressure buildup that would otherwise cause sticking between the rod seal and wiper seal.
2Reliability
If conventional seals without notches are used, then sealing is provided, but the seals stick to the radial walls of the groove due to adhesion
Solution Approach 1:
The seal lips are segmented with radially extending notches that create separation zones. These notches prevent continuous contact between the seal and groove wall, eliminating adhesion-based sticking while preserving sealing functionality at the lip edges.
Solution Approach 2:
The notches are strategically positioned on the axial face portions of the seal lips, creating localized non-sticking zones. The sealing edges remain intact for sealing, while the notched areas provide adhesion-free movement zones, achieving local quality differentiation.
3Strength
If seals without integrated back-up rings are used, then the seal body material provides basic extrusion resistance, but superior extrusion resistance into the gap between rod and housing is insufficient
Solution Approach 1:
The back-up ring is merged with the seal body to form an integrated unit. This combination provides superior extrusion resistance by placing a harder, more extrusion-resistant material directly behind the seal lip, preventing material extrusion into the rod-housing gap while maintaining structural simplicity.
Solution Approach 2:
The seal assembly uses composite construction with the seal body made of elastomeric material and the back-up ring made of harder material with superior extrusion resistance. This composite structure combines the sealing benefits of elastomers with the extrusion resistance of harder materials.
4Reliability
If conventional seals are used, then sealing is provided, but fluid leakage occurs through the opening between rod and housing
Solution Approach 1:
The sealing system is segmented into multiple seals (buffer seal, rod seal, wiper seal) with overlapping sealing zones. This segmentation creates multiple barriers to fluid leakage, ensuring that if one seal experiences wear or degradation, other seals maintain sealing effectiveness.
Solution Approach 2:
The buffer seal is positioned ahead of the rod seal to provide preliminary sealing and pressure relief. This beforehand cushioning prevents excessive pressure buildup that could force fluid past the rod seal, reducing fluid leakage before it occurs.
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
The improved seal system effectively minimizes fluid leakage, prevents pressure buildup, and provides superior extrusion resistance, ensuring reliable sealing and efficient fluid management in hydraulic systems.
Implementation Method 1
The notches prevent the seal from sticking to the radial wall of the groove, via the work of adhesion as a component of surface tension
Implementation Method 2
The hinge portion of the static lip allows pressure relief when the rod is retracted (moved back toward the system pressure side) thereby minimizing pressure build up between the rod seal and buffer seal
Implementation Method 3
The back-up ring is an integrated part of the buffer seal, used to provide superior extrusion resistance (into a gap created between the rod and the housing) than the material used to make the main body of the seal can provide
Data Source
AI summary
A seal system for a reciprocating cylinder includes a buffer seal, a rod seal, and a wiper seal. The buffer seal includes a dynamic seal lip and a static lip extending from a hinge portion. The hinge portion of the static lip allows fluid to escape past the outer diameter of the seal when the rod is retracted thereby releasing any pressure build-up between the rod seal and buffer seal. The axial face portion of the dynamic seal lip includes axially extending notches therein. The notches prevent the buffer seal from sticking to the axial wall of the groove and provide a consistent path for the fluid to energize the annular groove between the static and dynamic lips during the extension phase which is necessary for the function of the seal. The back-up ring is an integrated part of the buffer seal, used to provide superior extrusion resistance. The rod seal includes an annular seal body having a dynamic seal lip angularly extending radially inwardly and axially from the seal body, and a static lip angularly extending radially outwardly and axially from the seal body. An axial face portion of the dynamic seal lip and the static lip each include radially extending notches therein. The notches prevent the seal from sticking to the axial walls of the groove the rod seal is installed in and provides a consistent path for the fluid to energize the annular groove created by the static and dynamic lip during the extension phase. The back-up ring is an integrated part of the rod seal, used to provide superior extrusion resistance.