Hydraulic Cylinder Buffer Seal Backup Ring for Groove Wear
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Solution Overview
Problem
Hydraulic cylinder sealing arrangements in heavy machinery are prone to damage and failure due to exposure to abrasive materials, leading to leaks and contamination, as the annular grooves in the cylinder head and flange become worn out from relative movement with embedded contaminants.
Innovation Solution
A seal assembly comprising an annular buffer seal with a radially outer and inner annular seal surface, forming a notch around its inner diameter, and an annular backup ring extending along the radially outer seal surface, which reduces wear and enhances sealing by distributing contact forces and accommodating pressure variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sealing arrangements are used in hydraulic cylinders, then the sealing function is provided, but the annular grooves become damaged and worn due to abrasive materials in aggressive applications
Solution Approach 1:
A buffer seal is introduced as an intermediary component between the piston rod and the annular groove. This buffer seal absorbs the harmful effects of abrasive contaminants by providing a sacrificial sealing surface that protects the metallic annular groove from direct contact with embedded particles, thereby preventing groove damage while maintaining sealing reliability
Solution Approach 2:
The buffer seal acts as a protective cushion that is installed beforehand to absorb and distribute the impact and wear forces from abrasive materials. By positioning the buffer seal in advance, the annular groove is pre-protected from the harmful effects of contaminants before they can cause damage during hydraulic cylinder operation
2Reliability
If seals are positioned to prevent leakage, then sealing is achieved, but contaminants become imbedded in the seal face causing groove wear over time
Solution Approach 1:
The buffer seal serves as a mediator between the contaminant-laden environment and the annular groove. It maintains sealing effectiveness by blocking contaminant ingress while simultaneously protecting the annular groove from wear by absorbing the wear damage itself, thereby extending the service life of the groove
Solution Approach 2:
The buffer seal is designed as a sacrificial component that is relatively inexpensive and replaceable. It intentionally absorbs wear damage from embedded contaminants, acting as a disposable element that protects the more valuable and longer-lasting annular groove. When the buffer seal wears, it can be replaced without damaging the groove
3Ease of operation
If relative movement occurs between seal and annular groove, then sealing function is performed, but grinding away of the annular groove creates steps and gaps leading to seal failure
Solution Approach 1:
The buffer seal acts as an intermediary that enables the necessary relative movement for sealing while preventing direct metal-to-metal contact between the seal and the annular groove. This mediation allows sealing action to occur without the grinding wear that would compromise the precision and integrity of the annular groove surface
Solution Approach 2:
The buffer seal provides beforehand cushioning protection to the annular groove surface, ensuring that the precise groove geometry is maintained during operation. By cushioning against the seal and absorbing wear forces, it prevents the grinding away that would create steps and gaps, thereby preserving the manufacturing precision of the groove
Data Source
AI summary
A seal assembly for a hydraulic cylinder piston rod of a hydraulic cylinder includes an annular buffer seal and an annular backup ring. A first axial pressure side of the annular buffer ring faces a rod end chamber of the hydraulic cylinder and fits adjacent a first axial side surface of an annular groove defined in a rod end of the hydraulic cylinder through which the piston rod passes, and a second axial seal side opposite from the first axial pressure side includes a radially outer annular seal surface and a radially inner annular seal surface, wherein the radially outer annular seal surface is spaced farther from the first axial pressure side of the annular buffer seal than the radially inner annular seal surface of the buffer seal such that an annular notch is formed around an inner diameter of the annular buffer seal on the second axial seal side of the annular buffer seal. The annular backup ring includes a radially extending leg portion that extends along substantially an entire radial extent of the radially outer annular seal surface of the annular buffer seal, and an axially extending leg portion that extends axially into the annular notch formed around the inner diameter of the annular buffer seal on the second axial seal side of the annular buffer seal.