Hydraulic Cylinder Seal Stack for Abrasive Contamination Control
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Solution Overview
Problem
Existing sealing arrangements for hydraulic cylinders, particularly in aggressive applications, face challenges such as damage to annular grooves, contamination, and eventual seal failure due to abrasive materials and relative movement between seals and grooves.
Innovation Solution
A combination of seals and wear guides is used in a hydraulic cylinder, including a cylindrical metallic wear guide, a buffer seal assembly with an annular buffer seal and backup ring, a U-cup seal, a cylindrical plastic wear guide, and a triple lip wiper seal, all axially spaced in annular grooves to provide a sealed engagement between the piston rod and the cylinder head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single seal is used in the annular groove, then the sealing arrangement is simple, but the seal is susceptible to damage from abrasive contaminants and relative movement
Solution Approach 1:
The sealing arrangement is divided into multiple independent seal elements (first seal, second seal, third seal) positioned at different axial locations. Each seal provides a separate sealing barrier, so if one seal becomes damaged or contaminated, the other seals continue to function, maintaining the overall sealing integrity of the hydraulic cylinder
Solution Approach 2:
The wear guide is positioned ahead of the seals to intercept and contain abrasive contaminants before they reach the seal faces. This preventive measure cushions the seals from direct contact with abrasive materials, reducing wear and extending seal life before failure occurs
2Reliability
If multiple seals are used to prevent contamination, then sealing performance improves, but the risk of groove damage from abrasive materials increases
Solution Approach 1:
The wear guide acts as an intermediary element positioned between the external environment and the seals. It intercepts abrasive contaminants and contains them in a dedicated space, preventing direct contact between the abrasives and the seal faces, thereby protecting the seals and groove from damage
Solution Approach 2:
The wear guide is designed as a sacrificial component that can be easily replaced. It absorbs the wear and damage from abrasive contaminants, protecting the more expensive and critical seal elements. When the wear guide becomes damaged, it can be replaced without replacing the entire sealing assembly
3Device complexity
If seals engage directly with the annular groove, then the sealing arrangement is compact, but relative movement causes grinding and step formation
Solution Approach 1:
The wear guide serves as a mediator between the moving seal and the stationary groove. It provides a wear-resistant surface that the seal can slide against, preventing direct metal-to-metal contact between the seal and the groove, thereby eliminating grinding and step formation
Solution Approach 2:
The wear guide is made from materials with superior wear resistance and friction properties compared to the groove material. By changing the material parameters of the contact surface, the system reduces friction and wear, preventing the formation of steps and maintaining groove surface integrity over time
Data Source
AI summary
A combination of seals and wear guides for use in a hydraulic cylinder provides a sealed engagement between a piston rod of the hydraulic cylinder and an inner circumferential surface of a rod end of a cylinder barrel of the hydraulic cylinder through which the piston rod is axially movable. The combination includes a cylindrical metallic wear guide for seating within a first annular groove formed around the inner circumferential surface, a buffer seal assembly including an annular buffer seal cooperatively mated with an annular backup ring for seating within a second annular groove, a U-cup seal for seating within a third annular groove, a cylindrical plastic wear guide for seating within a fourth annular groove, and a triple lip wiper seal including three ringed lip portions for seating within a fifth annular groove.