Experimental and numerical investigation of six-bar linkage application to bellow globe valve for compact design

Abstract

Bellow sealing in valves provides the characteristic of no emission sealing by extending or compressing within the elastic limit to operate the valve. To keep the motion of the bellow within the elastic limit, a long length of bellow is required, which increases the length of the shaft and height of the valve. Increased height restricts valve usage, especially for large sizes, due to the limited platform space. This study presents the application of a six-bar linkage to operating mechanism by replacing the reciprocating shaft in an attempt to reduce the height of the valve. The mechanism produced aims to reduce the input displacement while maintaining the output displacement in order to reduce the required bellow length. Graphical synthesis of the mechanism was carried out using Autodesk Inventor. The designed mechanism was then subjected to analysis using a simulation tool for the position, force, and flow analysis. The prototype valve with the application of the new mechanism was manufactured using additive manufacturing, which was later used for experimental testing. Application of the mechanism to the bellow valve reduced the required input by 75%, which as a result, reduced the height of the valve up to 50%. The force analysis depicted that the force required to operate the mechanism was approximately eight times higher than the conventional design. Flow analysis of the valve showed that the introduction of the new mechanism had no effect on the flow efficiency of the valve and the flow coefficient of valve remained the same. Application of the six-bar linkage to the valve control mechanism made the design of the valve compact when compared to conventional design in terms of height, which makes it more suitable for use in industry.