Fluoroplastic Butterfly Valve Sealing Structure for Low Torque
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Solution Overview
Problem
Conventional fluoroplastic butterfly valve designs face challenges in achieving high temperature and pressure resistance, low torque requirements, and long service life, especially when handling corrosive liquids like hydrofluoric acid and hydrochloric acid, due to issues with material deformation, interference sliding, and fluid torque, which affect sealing efficiency and reliability.
Innovation Solution
A fluoroplastic butterfly valve structure featuring a valve body with a trapezoidal groove for a back-up ring, a lining with reinforcement portions, and a butterfly disc with unequal-width conical and curved surfaces to reduce material deformation and friction, enhancing sealing width and pressure resistance while minimizing torque and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fluoroplastic butterfly valve design is used, then sealing function is provided, but material deformation occurs under high temperature and pressure, reducing sealing reliability
Solution Approach 1:
The patent employs a composite structure consisting of an inner metallic butterfly disc (304 stainless steel) providing mechanical strength and dimensional stability, combined with an outer fluoroplastic encapsulation layer providing corrosion resistance and sealing functionality. This composite construction allows the valve to maintain sealing reliability under high temperature and pressure by preventing fluoroplastic deformation while retaining its protective properties.
Solution Approach 2:
The patent modifies the physical parameters of the sealing surface by creating an unequal-width conical surface on the metallic disc and a corresponding curved surface on the fluoroplastic encapsulation. This geometric parameter change optimizes the contact pressure distribution and reduces material deformation under operating conditions, thereby improving sealing reliability.
2Duration of action of moving object
If fluoroplastic lining is used for corrosion resistance, then service life is extended, but torque requirement increases due to friction during closing
Solution Approach 1:
The patent applies local quality optimization by creating an unequal-width conical surface on the metallic disc where the contact width varies along the sealing surface. This local geometric variation reduces the frictional contact area during the closing motion, thereby reducing the torque requirement while maintaining the corrosion-resistant fluoroplastic lining for extended service life.
Solution Approach 2:
The patent introduces curved surfaces on both the metallic disc (conical surface) and the fluoroplastic encapsulation to replace flat sealing surfaces. This curvature optimization reduces the contact pressure concentration and minimizes friction during closing, lowering torque requirements while preserving the protective fluoroplastic lining.
3Reliability
If interference sliding is designed for tight sealing, then sealing width is improved, but friction increases leading to higher torque and wear
Solution Approach 1:
The patent optimizes the geometric parameters of the sealing surfaces by designing an unequal-width conical surface on the metallic disc and a corresponding curved surface on the fluoroplastic encapsulation. This parameter optimization achieves tight sealing with adequate contact pressure while minimizing the frictional contact area, thereby reducing wear and torque requirements.
Solution Approach 2:
The patent employs curved sealing surfaces (conical and curved geometries) to replace traditional flat or uniform sealing surfaces. This curvature design distributes the contact pressure more effectively, achieving tight sealing with reduced friction and wear compared to conventional interference sliding designs.
4Ease of manufacture
If conventional symmetric butterfly disc structure is used, then manufacturing is simplified, but pressure resistance and sealing performance at high temperature are insufficient
Solution Approach 1:
The patent uses a composite structure with an inner metallic disc (304 stainless steel) providing high strength and pressure resistance, combined with an outer fluoroplastic encapsulation layer providing corrosion resistance. This composite design achieves superior pressure resistance and high-temperature performance while maintaining reasonable manufacturing complexity through a systematic construction approach.
Solution Approach 2:
The patent applies local quality enhancement by concentrating the complex geometric features (unequal-width conical surface and curved surface) only at the sealing periphery of the butterfly disc, while the central portion remains simpler. This localized complexity optimization maintains ease of manufacture for the bulk structure while achieving high pressure resistance and sealing performance at critical areas.
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 improved resistance to high temperatures and pressures, reduced torque requirements, and extended service life by minimizing material deformation and friction, ensuring reliable sealing and increased flow capacity.
Implementation Method 1
The back-up ring 94 is made of rubber and mounted between the annular groove 912 of the inner peripheral surface 911 and a tubular portion 931. Therefore, the back-up ring 94 compensates for the insufficient elasticity of the fluoroplastic, provides a high amount of deformation, decreases the demand for torque, provides an inner surface 933 of the lining with the required support of deformation, and provides an butterfly disc outer rim 922 and the inner surface 933 of the lining with a press sealing ability.
Implementation Method 2
A fluoroplastic butterfly disc (5) having an outer rim (53) and encapsulated by the fluoroplastic material (69) is provided. The fluoroplastic material provides a corrosion resistant and temperature resistant fluoroplastic lining (3).
Implementation Method 3
The outer rim of the butterfly disc has an interference sliding while closing, and a tight press sealing is attained in a full closed state. The unequal-width conical and curved surfaces are designed to minimize contact area and friction during operation.
Data Source
AI summary
A fluoroplastic butterfly valve structure is disclosed that includes an inner metallic butterfly disc and an outer fluoroplastic material enclosing the metallic butterfly disc within a valve body. The butterfly disc has a board-like or cone-like cross section. A fluoroplastic lining has an interference fit with the butterfly disc. A back-up ring is provided between an inner surface of the valve body made of high temperature resistant rubber. The butterfly disc has a complex sealing structure, which includes an unequal-width conical surface and an unequal-width curved surface. The unequal-width curved surface is disposed in a closing direction of the butterfly disc for preventing interference sliding thereof.