Dynamic Backup Ring Assembly for High-Pressure Seal Extrusion
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Solution Overview
Problem
Dynamic seals in high-pressure applications face challenges with extrusion damage due to heavily loaded shaft-to-housing contact, misalignment, and pressure-induced deformation, limiting their ability to maintain sealing effectiveness under differential pressure.
Innovation Solution
A backup ring mechanism that applies pressures from both fluids to achieve radial and axial force balance, allowing the backup ring to align with shaft movement and maintain a small extrusion gap, minimizing damage and enhancing sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the extrusion gap clearance is made small to avoid extrusion damage, then sealing effectiveness is improved, but the risk of heavily loaded shaft-to-housing contact increases
Solution Approach 1:
A backup ring is introduced as an intermediary component between the dynamic seal and the shaft-to-housing interface. The backup ring carries the lateral loads and prevents heavily loaded contact between the housing and shaft, while allowing the extrusion gap clearance to remain small for effective sealing. This mediator absorbs the harmful forces that would otherwise compromise the sealing system.
2Strength
If the shaft-to-housing clearance is reduced to prevent extrusion damage, then extrusion resistance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The backup ring serves as a mediator that decouples the extrusion gap clearance from the shaft-to-housing clearance requirements. By introducing this intermediate component, the system can maintain a small extrusion gap for high extrusion resistance while using larger, more manufacturable shaft-to-housing clearances that accommodate normal manufacturing tolerances.
3Stability of the object's composition
If the housing is made rigid to maintain extrusion gap clearance, then extrusion gap stability is improved, but pressure-induced deformation increases
Solution Approach 1:
The backup ring is designed with dynamic characteristics that allow it to flex and adapt to pressure-induced deformations of the housing. Rather than requiring the housing to remain perfectly rigid, the backup ring compensates for housing deformation, maintaining stable extrusion gap clearance under varying pressure conditions. This dynamic approach reduces the stress requirements on the housing structure.
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 solution effectively reduces extrusion damage and maintains sealing integrity under high differential pressures by ensuring the backup ring remains balanced and aligned with shaft movements, thereby extending the life and efficiency of dynamic seals.
Implementation Method 1
A backup ring mechanism that applies pressures from both fluids to achieve radial and axial force balance
Implementation Method 2
applies pressures from both fluids to achieve radial and axial force balance
Data Source
AI summary
A seal backup ring assembly is provided that eliminates fluid differential pressure acting radially on the backup ring, preventing collapse of the backup ring against a shaft. The backup ring is assembled so that the initial clearance (extrusion gap) between the backup ring and relatively rotating member is not affected by the differential pressure acting across the assembly. This allows for an initially small extrusion gap to be present throughout the differential pressure range.