Self-Energized Backup Ring for High-Pressure Seal Retention
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Solution Overview
Problem
Conventional backup rings for mechanical seals, such as o-rings, often fail to effectively fill large clearance gaps and maintain seals at high pressures, and can be difficult to retain within the gland, especially in face seal applications.
Innovation Solution
A self-energized backup ring design that radially interferes with the gland to create hoop stress, allowing it to automatically fill gaps and be retained through interlocking features, ensuring effective sealing at high pressures with minimal external pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional backup rings are used to prevent o-ring extrusion, then extrusion protection is provided, but the backup rings cannot effectively fill large clearance gaps and fail at high pressures
Solution Approach 1:
The backup ring is designed with a dynamic self-energizing mechanism where system pressure automatically activates the retention mechanism. The pressure differential causes the backup ring to be urged into the clearance gap, transforming from a static component to an actively engaged sealing element that responds to operating conditions.
Solution Approach 2:
The invention changes the operational parameters of the backup ring by introducing pressure-activated engagement. The retention mechanism remains inactive at low pressures but automatically engages when pressure exceeds a threshold, allowing the backup ring to transition between different functional states based on system pressure conditions.
2Ease of operation
If conventional backup rings are used, then some extrusion prevention is achieved, but the backup rings are difficult to retain within the gland, especially in face seal applications
Solution Approach 1:
The retention mechanism is designed to preemptively counteract forces that would dislodge the backup ring from the gland. The geometry of the retention features creates mechanical interference that prevents removal before assembly is complete, and during operation, the self-energizing pressure further secures the backup ring in place.
Solution Approach 2:
The backup ring's retention is partially self-service through the self-energizing mechanism. System pressure automatically activates the retention features, causing the backup ring to lock itself into the gland without requiring additional external retention forces or complex assembly procedures.
3Reliability
If tight machining tolerances are maintained on mating components, then acceptable sealing is achieved at high pressures, but manufacturing cost increases significantly
Solution Approach 1:
The backup ring serves as an intermediary element between the o-ring and the clearance gap. It absorbs the high-pressure loads and prevents o-ring extrusion into the gap, allowing the mating components to be manufactured with normal tolerances while maintaining sealing effectiveness at pressures exceeding 1500 psi.
4Ease of operation
If the clearance gap between sealing faces is increased, then assembly ease is improved, but the o-ring's pressure resistance decreases without external support
Solution Approach 1:
The backup ring acts as a mediator that allows the clearance gap to be larger for easier assembly while maintaining pressure resistance. It fills the gap and provides structural support to the o-ring, preventing extrusion even when the gap is too large for the o-ring to bridge alone.
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 self-energized backup ring effectively fills large gaps and maintains pressure integrity up to high pressures (8-15K psi) with minimal force, preventing o-ring extrusion and ensuring reliable sealing even in face seal applications.
Implementation Method 1
A self-energized backup ring design that radially interferes with the gland to create hoop stress
Implementation Method 2
some backup rings may be energized by the o-ring, meaning that compressing the o-ring also urges the backup ring into the clearance gap
Data Source
AI summary
An apparatus is disclosed in one embodiment of the invention as including an annular seal (e.g., an o-ring) and a backup ring to provide support to the annular seal. A gland is provided to accommodate the backup ring and the annular seal. The gland has a contact surface which is adapted to contact a corresponding contact surface of the backup ring upon inserting the backup ring into the gland. The diameters of the contact surfaces of the backup ring and gland are sized such that the contact surface of the backup ring radially interferes with the contact surface of the gland, thereby urging the backup ring out of the gland. A retention mechanism, such as interlocking grooves, protrusions, ridges, notches, slots, or the like may be provided in the backup ring and gland respectively to prevent the backup ring from completely exiting the gland.