Butterfly Valve Ring Retainer Reduces Friction
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Solution Overview
Problem
Conventional butterfly valves experience wear and friction due to the expansion of rings against the bore, leading to increased leakage and reduced effectiveness over time, which can be costly to mitigate with wear-resistant materials or coatings.
Innovation Solution
A ring retainer is used to restrain the radial expansion of the rings, preventing friction and wear by maintaining a consistent fit between the rings and the bore, allowing the valve to operate with minimal or no friction throughout its service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rings are permitted to expand freely to accommodate wear, then sealing effectiveness is maintained, but friction and wear between rings and bore increase continuously
Solution Approach 1:
The ring is designed with dynamic expansion capability through a segmented structure with gaps, allowing it to expand and contract based on operational conditions. The gaps enable the ring to accommodate thermal expansion and wear while maintaining sealing contact, yet the expansion is controlled to prevent excessive friction during actuation.
Solution Approach 2:
The ring's physical parameters (dimensional stability, expansion ratio) are modified by creating a segmented structure with controlled gaps. This allows the ring to change its effective diameter dynamically - expanding to maintain seal contact with the bore while limiting expansion during actuation to reduce friction and wear.
2Manufacturing precision
If high precision machining is used to center rings in the bore, then initial sealing is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The segmented ring structure with gaps enables self-centering through elastic deformation. When the ring expands, the gaps close and the ring naturally conforms to the bore's geometry, automatically finding its center position without requiring high-precision machining or complex centering mechanisms.
Solution Approach 2:
The ring is designed as a flexible, elastic component that can deform to accommodate misalignment and find its center position. The gaps in the ring structure provide the necessary flexibility for the ring to elastically deform and self-center within the bore, eliminating the need for high-precision manufacturing.
3Reliability
If rings are forced radially outward by fluid pressure, then sealing contact is maintained, but friction increases with fluid pressure
Solution Approach 1:
The segmented ring structure allows dynamic response to fluid pressure. The gaps enable the ring to expand progressively under pressure, maintaining sealing contact while the segmented design distributes the pressure load, preventing excessive friction force during actuation.
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 significantly reduces wear and friction, extending the valve's life by minimizing initial wear to less than 1% of the total cycles, with the valve maintaining a slip fit for the majority of its operational life, reducing the need for costly materials and precise manufacturing.
Implementation Method 1
Rings are typically employed to accommodate surface irregularities and manufacturing tolerances of the butterfly, minimizing inherent leakage that can occur between the butterfly and the housing or passage in which the butterfly is placed. In conventional butterfly valves, the rings expand to the diameter of the housing or passage bore during actuation of the butterfly. In this manner, the rings function as resilient components that accommodate the surface irregularities and manufacturing size tolerances of the butterfly.
Implementation Method 2
In some designs, these rings can be forced radially outwards by fluid pressure that acts within the butterfly groove between the butterfly disc and the inside edge of the ring or rings. When the fluid pressure is high, the force pressing the rings outward is high.
Data Source
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AI summary
A butterfly valve for controlling the flow of fluid within a bore, including a butterfly and at least one ring extending at least one of substantially and completely around a perimeter of the butterfly and adapted to develop an expansion force in the radial direction when the at least one ring is in a contracted state with respect to the radial direction, wherein the at least one ring is secured to the butterfly in the contracted state and radial expansion due to the developed expansion force of the at least one ring is effectively restrained, wherein the butterfly valve is adapted to operate, when placed in a bore, without friction or substantially without friction between the at least one ring and the bore when the butterfly valve is placed in a closed position within the bore.