Butterfly Valve Sealing Geometry for Low-Torque Shutoff
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Large-diameter butterfly valves face challenges in maintaining sealing performance while minimizing operating torque, as increasing surface pressure to ensure sealing leads to higher resistance and torque, and reducing pressure compromises sealing near through-holes, leading to potential leakage.
Innovation Solution
The butterfly valve design features a valve element with annular outer peripheral edge surfaces and chamfered surfaces inclined at a predetermined angle, concentrating pressure on a planar peripheral edge sealing surface to enhance sealing while reducing resistance during rotation, and an annular protrusion on the seat ring with specific groove and transition surfaces to maintain uniform crushing margin and improve sealability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface pressure that presses the outer peripheral edge surface against the valve seat surface is increased to ensure sealing, then the sealing performance is improved, but the resistance when rotating the valve element increases and the operating torque increases
Solution Approach 1:
The invention applies local quality by providing raised portions at specific locations on the outer peripheral edge surface of the valve element - namely at positions opposite the through-holes and at intermediate positions between them. These raised portions concentrate the sealing pressure locally at the valve seat contact points, ensuring adequate sealing force even when the overall surface pressure is reduced to lower operating torque.
Solution Approach 2:
The invention segments the outer peripheral edge surface of the valve element into multiple distinct raised portions rather than using a single continuous sealing surface. This segmentation allows different regions to serve specific functions: the raised portions at through-hole opposites provide sealing where leakage is most likely, while intermediate raised portions distribute pressure to maintain sealing without excessive overall pressure.
2Ease of operation
If the outer peripheral edge surface is shaped like a spherical surface to reduce operating torque, then the ease of operation is improved, but the sealing performance near through-holes deteriorates due to low effective surface pressure
Solution Approach 1:
The invention overrides the spherical surface approach near through-holes by introducing raised portions at positions opposite the through-holes. These localized raised portions concentrate sealing pressure precisely where the spherical surface would otherwise create low pressure zones, preventing leakage at the most vulnerable sealing locations while preserving the overall low-torque spherical geometry.
Solution Approach 2:
The raised portions are positioned in advance at locations where leakage is most likely to occur (opposite through-holes and at intermediate positions). This preliminary anti-action counteracts the tendency of the spherical surface to create low pressure zones before the valve element makes contact with the seat, ensuring uniform sealing pressure distribution.
3Reliability
If the outer circumference of the seat ring is formed in an elliptic shape to increase crushing margin around through-holes, then the sealing performance is improved, but the device complexity increases
Solution Approach 1:
Instead of making the entire seat ring outer circumference elliptical, the invention applies local quality by providing raised portions only at specific locations on the valve element - at positions opposite through-holes and at intermediate positions. This localized approach achieves the same sealing enhancement without the complexity of an elliptical seat ring geometry.
Solution Approach 2:
The invention inverts the approach by modifying the valve element rather than the seat ring. Instead of changing the seat ring to an elliptical shape to increase crushing margin, the raised portions on the valve element create the necessary pressure concentration, achieving sealing improvement while maintaining simple circular geometries for both components.
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 effectively increases sealing pressure between the valve element and seat ring while reducing operating torque, ensuring reliable sealing performance and wear durability, even under repeated operation.
Implementation Method 1
chamfered surfaces inclined at a predetermined angle relative to the peripheral edge sealing surface toward the outer peripheral edge surface of the valve element and extending along both sides of the peripheral edge sealing surface
Implementation Method 2
a peripheral edge raised portion extending in the circumferential direction of the valve element so as to connect between the two opening raised portions... the peripheral edge sealing surface that extends along a top thereof to be like an arc in the circumferential direction and flat in the width direction
Data Source
AI summary
A butterfly valve includes a valve body with an internal flow passage, a seat ring attached to an inner peripheral surface of the internal flow passage, a valve stem rotatably supported by the valve body, and a valve element rotatably supported by the valve body via the valve stem. The valve element has an annular outer peripheral edge surface, and includes, at opposite positions in the direction of the rotation axis on the outer peripheral edge surface, two valve-stem openings for the valve shaft to pass therethrough. The outer peripheral edge surface of the valve element includes two annular opening raised portions each extending along the periphery of the corresponding valve stem openings, and peripheral edge raised portions connecting the two opening raised portions, each having a peripheral edge sealing surface extending along a top thereof, and chamfered surfaces inclined and extending along both sides of the peripheral sealing surface.