Triangular Stem Seal Structure for High-Pressure Extrusion Resistance
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Solution Overview
Problem
Current 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-stein corner and a hard metallic gland, combined with anti-extrusion rings, to ensure full compression and effective radial sealing, allowing the seal to withstand pressures equal to its material's strength and extrusion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional seal designs are used for moving rods and shafts, then the seal structure is simple and easy to manufacture, but the seal cannot accurately withstand the maximum allowable working pressure, leading to safety concerns
Solution Approach 1:
The seal is divided into multiple functional segments: a soft sealing ring for pressure transmission, a hard metallic 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, enabling the seal to withstand maximum allowable working pressures while maintaining manufacturability through standardized component fabrication
Solution Approach 2:
The seal system combines materials with different properties: soft materials (such as PTFE or rubber) for the sealing ring to enable pressure transmission and deformation, and hard materials (metallic gland) for structural integrity and compression application. This composite approach allows the seal to simultaneously achieve the flexibility needed for pressure tightness and the rigidity required for withstanding maximum working pressures
2Reliability
If a soft sealing ring is used to transmit pressure, then the seal can adapt to surface irregularities, but the material must be both soft and wear-resistant, which is difficult to achieve
Solution Approach 1:
Different regions of the seal system have different material properties optimized for their specific functions: the sealing ring uses soft material for conforming to surface irregularities and pressure transmission, while the metallic gland and anti-extrusion rings use hard, wear-resistant materials for structural support and gap control. This local differentiation allows each component to be manufactured from materials best suited to its function
Solution Approach 2:
The seal design changes the physical parameters of the soft sealing ring through controlled compression by the metallic gland, transforming the material from its uncompressed state to a compressed state where it exhibits enhanced sealing properties. The compression ratio and resulting density are carefully controlled to achieve both softness for adaptation and wear-resistance for durability
3Reliability
If the sealing ring is compressed from a great room to a small room to enable Poisson's deformation, then the seal can orthogonally transmit stress, but the angle Arctan(h/d) is very small and only changes response time
Solution Approach 1:
The metallic gland is designed to pre-compress the soft sealing ring to an optimal compression ratio during installation, establishing the initial Poisson's deformation state before service. This preliminary compression ensures that the sealing ring is pre-positioned to achieve orthogonal stress transmission capability, eliminating the need for precise field adjustments
Solution Approach 2:
The seal system uses the process fluid pressure itself to maintain and adjust the compression state of the sealing ring during operation. The fluid pressure acts on the sealing ring to sustain the Poisson's deformation and orthogonal stress transmission, making the system self-regulating without requiring external adjustment mechanisms
4Reliability
If an anti-extrusion ring is added to resist extrusion through gaps, then the seal can withstand higher pressures, but the device complexity increases
Solution Approach 1:
The anti-extrusion ring serves as an intermediary component positioned between the soft sealing ring and the extrusion gap. It transfers the compressive load from the metallic gland through itself to the sealing ring, while simultaneously blocking the extrusion path. This intermediary structure enables high pressure resistance by managing the extrusion forces without requiring fundamental redesign of the primary sealing elements
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 triangular soft ring to transmit pressure equally in all directions, 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 ability for a liquid to transmit a pressure in time equally in each direction originates from its softness and its volume incompressibility
Implementation Method 2
the Poisson's ratio μ is an index of liquid behavior and incompressibility of a general object; since material's Poisson's ratio μ is the ratio of its strain in the non-compressed transverse direction to its strain in the compressed longitudinal direction
Implementation Method 3
objects that can effectively orthogonally transmit a stress can only be either a rigid body with wedging function or a closed liquid without extrusion gap
Data Source
AI summary
A pressure-tight stein cylinder seal and a self-energizing stein shoulder seal matching the stein 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 stein cylinder, to convert their original axial tightening force 2f respectively into a radial compression force 4f/√3 of their soft ring 04 on the stein 02 cylinder and another radial compression force 2f of their soft ring 06 on the stein 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-stein 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.