Triple Offset Butterfly Valve Wedge-Eccentric Stem Lock
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Solution Overview
Problem
Conventional triple offset butterfly valves face issues such as high leakage, premature wear, high operating torque, unpredictable actuation forces, risk of bolts falling into pipelines, and inability to maintain bidirectional seals under extreme conditions, limiting their application in severe services like rocket engine fuel control and high-temperature environments.
Innovation Solution
A triple offset butterfly valve design featuring a wedge-eccentric-thread joint/lock mechanism between the stem and disc, full metal wave seats, and a novel metal K ring stem seal system with spring bearings to compensate for thermal expansion and provide reliable, low-leakage seals, along with inline repairability and noise-reducing trims.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional laminated seat with metal rings and graphite rings is used, then sealing is achieved, but the seat is easily damaged and requires high preload and constant replacement
Solution Approach 1:
The patent extracts and eliminates the graphite rings and gaskets from the conventional laminated seat structure, replacing them with a fully metal seat design that uses metal-to-metal sealing surfaces. This simplifies the seat structure while improving reliability by removing the weak graphite components that require frequent replacement.
Solution Approach 2:
The patent employs composite metal seat structures with specific material combinations designed to provide both sealing capability and damage resistance. The metal seat incorporates hardened sealing surfaces combined with tougher supporting structures, creating a composite material solution that eliminates the need for graphite components.
2Reliability
If high preload is applied to secure seal between seat and disc, then sealing is improved, but operating torque increases significantly
Solution Approach 1:
The patent employs a triple offset mechanism that creates spherical or curved sealing surfaces instead of flat surfaces. The conical seat and disc geometry with specific offset angles allows the sealing surfaces to contact at optimal points, distributing the sealing force more efficiently and reducing the overall torque required to achieve and maintain the seal.
Solution Approach 2:
The patent changes the geometric parameters of the sealing surfaces, specifically the angle and orientation of the conical seat and disc surfaces. By optimizing these parameters, the seal is achieved with lower normal forces, which directly reduces the operating torque while maintaining seal integrity.
3Ease of manufacture
If axial bolting joint with direct screws is used to secure seal rings, then assembly is simple, but bolts may fall into pipelines under vibration
Solution Approach 1:
The patent introduces an intermediary retaining ring structure that acts as a mediator between the bolts and the seal ring. This retaining ring captures and holds the bolts in place, preventing them from falling into the pipeline while still allowing simple axial assembly. The intermediary component solves both the assembly simplicity and vibration reliability requirements.
4Ease of manufacture
If key/pin joint is used between stem and disc, then connection is simple, but strength is reduced with high stress concentration
Solution Approach 1:
The patent segments the connection between stem and disc into multiple distributed connection points rather than a single key or pin. This segmentation distributes the stress across multiple locations, eliminating stress concentration while maintaining manufacturing simplicity. The segmented connection may take the form of multiple small keys, pins, or interference-fit features distributed around the stem-disc interface.
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 achieves reliable, low-leakage, bidirectional sealing with reduced operating torque and extended valve life, enabling operation in extreme conditions without constant readjustment or replacement, and allows for inline repair, significantly improving the valve's performance and durability.
Implementation Method 1
spring bearings are disposed in the bearing hole in the body to compensate valve assembly clearances for upstream seal as well as the thermal expansion of the stem
Implementation Method 2
full metal wave seats are disposed between conical mating solid seat on the body or the disc for providing seals
Implementation Method 3
wedge-eccentric-thread joint/lock mechanism between a stem and a disc in a middle is provided
Implementation Method 4
wedge-eccentric-thread joint/lock mechanism between a stem and a disc in a middle is provided
Implementation Method 5
two compression rings disposed in the stem below and above the I ring for converting a dynamic radial seal to a dynamic axial seal
Data Source
AI summary
This invention relates to a novel rotary control valve with new joint methods and flow control mechanisms, inline-reparability and fully metal seals more particularly to a triple offset butterfly valve or ball valve with those features used for on-off and flow controlling under multiple extreme conditions or in severe services; such as the integrated gasification combined cycle under high temperature and pressure, Fluid Catalytic Cracking under high temperature over 1200 F with hard diamond like catalytic particles, shale fracking process under extreme high pressure and high velocity fluid with solid particles and corrosive additives and other critical applications for products life lasting 5 to 30 years like deepsea flow control systems and nuclear power plants and for the applications of millions cycles like jet or rocket turbine engine fuel delivery systems with high velocity fuel fluid mixed with highly oxidative gas under temperature 1365 F.