Butterfly Valve Compound Shaft Disk Mounting
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Solution Overview
Problem
Large butterfly valves with polymer disks face challenges in handling corrosive and abrasive materials due to structural weakness, leading to issues like shearing of bolts and potential rupture, especially under pressure and temperature variations, which complicates the opening and closing mechanisms.
Innovation Solution
A two-part compound shaft with interlocking faces and sockets supports the disk rotationally, transferring torque effectively and preventing stress on fasteners, combined with an electric drive for precise control and a disk position indicator to prevent accidental seal inflation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a polymer disk is used in large butterfly valves, then the weight is reduced and corrosion resistance is improved, but the structural strength deteriorates leading to shearing of bolts and potential rupture
Solution Approach 1:
The shaft is divided into two separate parts (first shaft and second shaft) that extend into the disk from opposite sides. This segmentation allows the shaft to be more flexibly supported and reduces the stress concentration on any single fastener, enabling the lightweight polymer disk to be securely mounted without requiring excessive fastening force that could cause shearing.
Solution Approach 2:
The two shaft parts are combined through interlocking engagement to form a unified support structure for the disk. This merging provides distributed support across multiple engagement points, enhancing the overall structural strength and stability of the disk assembly while maintaining the benefits of using a lightweight polymer material.
2Device complexity
If a single shaft supports the disk, then the structure is simple, but the torque transfer is insufficient and stress on fasteners increases under pressure variations
Solution Approach 1:
The shaft is segmented into two separate parts that independently engage with the disk. This segmentation distributes the torque transfer across multiple engagement points and reduces the mechanical stress on individual fasteners, preventing shearing and improving reliability under varying pressure conditions.
Solution Approach 2:
Each shaft part has interlocking faces specifically designed to engage with corresponding sockets in the disk, creating localized high-strength engagement zones. This local quality enhancement ensures reliable torque transfer and fastener protection at critical stress points without requiring complex overall structure.
3Productivity
If the disk is quickly rotated for rapid opening and closing, then the productivity is improved, but the inertial forces on the shaft-disk connection increase and may cause failure
Solution Approach 1:
The segmented shaft structure with two separate parts provides distributed support and torque transfer paths. This segmentation reduces the inertial forces concentrated at any single connection point during rapid disk rotation, preventing connection failure while maintaining high operational speed for improved productivity.
Solution Approach 2:
The interlocking faces and sockets create a robust mechanical connection that anticipates and cushions against the inertial forces generated during rapid disk rotation. This beforehand cushioning prevents sudden connection failures and protects the shaft-disk interface during high-speed operations.
Data Source
AI summary
A lightweight butterfly valve having a disk maintained in a fixed position on a compound shaft through an interlocking relation ship between each of the individual shafts of the compound shaft and the disk as the disk is moveable between an open or closed position with the butterfly valve may having other features such as an electric drive to quickly rotate the compound shaft to provide for rapid opening and closing the butterfly valve, a disk position indicator and a shaft stop to prevent the disk from being driven past a full open condition.