Stepped Groove Seal Ring Backup Structure to Prevent Insertion Damage
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Solution Overview
Problem
Conventional high-pressure sealing devices with triangular-section backup rings face damage during installation due to increased diameter compression, leading to interference with shaft hole edges and potential damage.
Innovation Solution
A sealing device design featuring a first backup ring with a trapezoidal section and a second backup ring with a matching trapezoidal section, where the first backup ring is installed at a step in the mounting groove and the second backup ring is softer, with specific surface orientations and dimensions to prevent deformation and interference during insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If triangular-section backup rings are used in conventional sealing devices, then the structure is simple and easy to manufacture, but the first backup ring deforms and increases in diameter during insertion, causing interference with shaft hole edges and potential damage
Solution Approach 1:
The backup ring is designed with an asymmetric trapezoidal cross-section instead of a symmetric triangular section. The trapezoidal shape has a larger base at the non-sealed-fluid side and a smaller top at the sealed-fluid side, creating an asymmetric geometry that prevents radial expansion during insertion while maintaining structural integrity and pressure resistance.
Solution Approach 2:
The geometric parameters of the backup ring are changed from a triangular section to a trapezoidal section with specific angle relationships. The slope angles are designed such that the non-sealed-fluid-side slope is greater than the sealed-fluid-side slope, which fundamentally changes the deformation characteristics under compression and prevents diameter increase during installation.
2Strength
If the first backup ring is made hard to prevent seal ring damage, then the seal ring is protected from protruding, but the hard first backup ring is more susceptible to damage during insertion due to deformation
Solution Approach 1:
The asymmetric trapezoidal cross-section is designed so that the larger base is positioned at the non-sealed-fluid side where the hard material is most needed for structural support. The smaller top at the sealed-fluid side reduces stress concentration during insertion, allowing the hard material to maintain its strength while reducing susceptibility to damage during installation.
Solution Approach 2:
Different regions of the backup ring are optimized with different geometric properties. The base region (non-sealed-fluid side) has a larger cross-sectional area for strength and support, while the top region (sealed-fluid side) has a smaller area to reduce insertion stress. This local quality differentiation allows the hard material to provide protection where needed while minimizing damage risk during installation.
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 design effectively prevents damage to the first backup ring by controlling its diameter expansion, ensuring proper insertion and enhancing sealing performance by distributing pressure effectively across both backup rings.
Implementation Method 1
a second backup ring which is disposed, in the mounting groove, between the seal ring and the first backup ring at a part other than the step and which is softer than the first backup ring
Data Source
AI summary
A sealing device has a seal ring in a groove having a step, a first backup ring at the step in the groove, and a second backup ring, in the groove, between both rings offset from the step. The first backup ring includes a bottom-surface-side peripheral surface facing the step's bottom surface, an end surface facing the step's non-sealed-fluid-side side surface, a peripheral surface adjacent to the other member and facing the other member, and a slope facing the second backup ring. The length of the bottom-surface-side peripheral surface is equal to or smaller than the length of the bottom surface of the step. The second backup ring includes a peripheral surface facing the bottom surface of the groove, an end surface facing the non-sealed-fluid-side side surface of the groove, a slope facing the slope of the first backup ring, and a sealed-fluid-side end surface facing the seal ring.