Triangular Stem Seal Structure for High-Pressure Rod Sealing
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Solution Overview
Problem
Existing seal designs for moving rods and shafts in fluid power and medium conveying systems cannot be accurately computed or designed to meet the maximum allowable working pressure, leading to safety concerns in pressure vessels and systems.
Innovation Solution
The development of equilaterally triangular ring seals with a truncated off-stem corner and a hard metallic gland, combined with anti-extrusion rings, to ensure full compression and uniform circumferential sealing, allowing the seals to withstand pressures up to 0.5 times the material's strength, and the use of anti-extrusion metallic or coiled rings to enhance pressure resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional seal designs are used, then ease of manufacture is maintained, but the seals cannot accurately withstand maximum allowable working pressure
Solution Approach 1:
The seal is divided into multiple functional segments: a soft sealing ring for pressure transmission, a hard gland for structural support and compression application, and anti-extrusion rings for gap management. This segmentation allows each component to be optimized for its specific function while collectively achieving the required pressure resistance.
Solution Approach 2:
The seal system combines materials with different properties: soft materials (rubber, PTFE, lead) for the sealing ring to transmit pressure orthogonally, and hard materials (metallic gland) for structural integrity and compression application. This composite approach enables the seal to withstand maximum allowable working pressure while maintaining manufacturability.
2Reliability
If the sealing ring material is made soft for pressure transmission, then orthogonal stress transmission is improved, but extrusion resistance deteriorates
Solution Approach 1:
The hard metallic gland acts as an intermediary between the compression force and the soft sealing ring. It applies and maintains the compression force on the soft ring without being extruded itself, while the anti-extrusion rings prevent the soft ring from entering the gap between the gland and stem housing.
Solution Approach 2:
Different parts of the seal system have different material properties optimized for their local function: the soft sealing ring for pressure transmission, the hard gland for compression application and structural support, and the anti-extrusion rings for gap management. This local differentiation resolves the contradiction between softness for stress transmission and strength for extrusion resistance.
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
This design enables the creation of seals that can effectively transmit pressure and stress, ensuring a fully pressure-tight connection and meeting the requirements of maximum allowable working pressure, thereby enhancing the safety and reliability of fluid power and medium conveying systems.
Implementation Method 1
the Poisson's ratio μ is the ratio of its strain in the non-compressed transverse direction to its strain in the compressed longitudinal direction, any pliable material whose Poisson's ratio is smaller than 0.5 can be used for a sealing ring needing to orthogonally transmit a pressure or stress under normal temperature by compensating for its orthogonal strain ratio to 0.5 by a Poisson's deformation compensation angle
Implementation Method 2
a sliding fit with a small enough clearance is used to resist the extrusion of the triangular soft ring through the gap between the gland and the stem
Data Source
AI summary
A pressure-tight stem cylinder seal and a self-energizing stem shoulder seal matching the stem cylinder seal that both use an equilaterally triangular soft ring as their sealing element, wherein their designing rules are first, by means of wedging function of a hard gland coaxial with the stem cylinder, to convert their original axial tightening force 2f respectively into a radial compression force 4f/√3 of their soft ring 04 on the stem 02 cylinder and another radial compression force 2f of their soft ring 06 on the stem 02 shoulder and ensure that the two soft rings are so compressed from a great room to a small room as to be able to pass a pressure or stress exactly to each different direction, then to cut off their off-stem corners to give their cavities an opening or give each soft ring an axial compressing allowance, and last, by means of anti-extrusion metallic C-rings without axial resistance, to close each opening to provide a full support for the sealing deformation of their soft rings compressed in their cavities.