Metallic Shaft Seal Assembly With Adjustable Compression
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Solution Overview
Problem
Current metallic sealing solutions for rotating shafts face limitations in sealing performance, compactness, and adjustability, especially at high temperatures or with incompatible fluids, and often require complex and costly designs.
Innovation Solution
A metallic sealing assembly featuring a flexible joint with two concentric tori, a metallic envelope, and a spacer system that allows for adjustable compression and easy assembly, enabling high sealing performance and compactness while accommodating variations in shaft circularity and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metallic sealing joint with an inner lip is used to seal against a rotating shaft, then sealing performance can be improved, but the tolerance requirements for diameter and circularity become very tight and the contact pressure required is significant
Solution Approach 1:
The patent changes the material parameter from rigid metal to elastomeric material, which allows the sealing lip to deform and adapt to shaft irregularities. This material parameter change eliminates the need for tight diameter and circularity tolerances while maintaining effective sealing contact.
Solution Approach 2:
The patent employs an elastomeric sealing lip that acts as a flexible element capable of conforming to the shaft surface. This flexibility allows the seal to compensate for circularity variations and maintain reliable sealing without requiring precise manufacturing tolerances.
2Reliability
If a metallic sealing joint is used to achieve sealing, then sealing performance can be improved, but the contact pressure required generates significant manoeuvring torque
Solution Approach 1:
The patent changes the material parameter to elastomeric, which provides sealing through material deformation rather than high contact pressure. This reduces the force required to maintain the seal, thereby lowering the manoeuvring torque while preserving sealing reliability.
3Adaptability or versatility
If graphite is used for sealing, then chemical compatibility spectrum is very large, but graphite is incompatible with certain fluids such as liquid sodium
Solution Approach 1:
The patent changes the material parameter from graphite to elastomeric material, which offers different chemical compatibility characteristics. Elastomeric materials can be selected to be compatible with specific fluids like liquid sodium, resolving the incompatibility issue while maintaining adaptability through material selection.
4Object-affected harmful factors
If a solidified joint with external cooling fins is used to seal liquid sodium, then sealing compatibility is achieved, but the valve top becomes massive, heavy and bulky
Solution Approach 1:
The patent changes the sealing mechanism from a solidified joint requiring external cooling to an elastomeric seal that functions at operating temperatures. This eliminates the need for cooling fins and associated mass, dramatically reducing valve top weight while maintaining compatibility with liquid sodium through appropriate elastomer selection.
5Volume of moving object
If a flexible metallic sealing joint with two concentric tori is used, then compactness and adjustability are improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple sealing functions into a single integrated elastomeric lip structure that simultaneously provides sealing, compensation for shaft irregularities, and adaptability to different operating conditions. This merging reduces the number of separate components needed, thereby reducing overall device complexity despite the sophisticated functionality.
Solution Approach 2:
The elastomeric sealing lip is designed to perform multiple functions: sealing against the shaft, compensating for circularity variations, adapting to temperature changes, and providing reliable sealing across different fluid conditions. This multi-functionality consolidates what would otherwise require multiple separate components, reducing device complexity.
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 solution provides enhanced sealing performance, compactness, and adjustable maneuvering stress, addressing the limitations of existing solutions by allowing for precise control of compression and reducing the risk of leakage and mechanical stress.
Implementation Method 1
the hyper-elasticity of the material is thus used to create a contact pressure of the lip on the shaft
Implementation Method 2
the sealing can only be obtained via a significant contact pressure
Data Source
AI summary
A metallic sealing assembly between a rotating shaft and a fixed frame comprises: a flexible metallic seal having two tori, inner and outer, that are concentric and of different average diameters, comprising a metal envelope which encases and holds the inner and outer tori; a shaft rotating about an axis of rotation, comprising an annular shoulder against which the seal comes to press; a counter-face, comprising a contact face against which the seal comes to press; a wedge block positioned around the rotating shaft such that the seal is held between the wedge block and the contact face, the wedge block mounted to slide on the rotating shaft; a metal part which forms a cap through which the rotating shaft passes and which is secured to the frame and/or to the counter-face, the rotating shaft being free to rotate with respect to the cap and axially secured to the cap.