Scarf Cut Backup Ring Prevents Split Separation Under High Pressure
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Solution Overview
Problem
Conventional backup rings tend to separate at the split in high-pressure applications, allowing O-rings to extrude and deteriorate, as they no longer provide a complete circumferential plane of protection.
Innovation Solution
A backup ring with a scarf cut slit at an angle of less than 20° relative to the planar top side and a slightly larger inner diameter than the component it is mounted on, which allows for overlap and maintains thickness during operation, preventing separation and supporting the O-ring effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a backup ring is cut completely through to facilitate installation, then ease of installation is improved, but reliability deteriorates because the backup ring separates at the split in high pressure applications
Solution Approach 1:
The backup ring is divided into two segments connected by a hinge, allowing the ring to be opened for installation and then closed to form a complete circumferential barrier. The hinge connection maintains structural integrity while enabling easy installation, resolving the contradiction between ease of installation and reliability.
2Strength
If the backup ring is made rigid to prevent O-ring extrusion, then protection of the O-ring is improved, but adaptability deteriorates because the rigid ring cannot accommodate pressure-induced expansion
Solution Approach 1:
The backup ring incorporates a hinge that allows the ring to dynamically adjust its shape in response to pressure changes. The rigid segments provide protection against O-ring extrusion, while the hinge enables the ring to accommodate expansion and maintain contact with the sealing surface, resolving the contradiction between strength and adaptability.
3Reliability
If the backup ring inner diameter is made exactly equal to the component outer diameter for tight fit, then sealing effectiveness is improved, but ease of installation deteriorates because the ring cannot be expanded for installation
Solution Approach 1:
The segmented design with hinge connection allows the backup ring to be opened into a C-shape for easy installation over the component, then closed to achieve a tight fit with the component outer diameter. This resolves the contradiction between sealing effectiveness and ease of installation.
Data Source
AI summary
A seal assembly is provided for sealing a gap with a high pressure side and a low pressure side between a first component and a second component. The seal assembly can include a primary seal configured to be arranged on the first component and spanning the gap on the high pressure side between the first and second component; and a backup ring configured to be arranged on the first component adjacent the primary seal on the low pressure side. The backup ring includes an inner diameter and a scarf cut slit at an angle that is a function of the inner diameter of the backup ring.