Actual indicator diagram mechanism

Abstract

The main aim of this project is to understand the mechanism of actual indicator diagram and its working principle. Furthermore to design and fabricate a low cost mechanical indicator prototype with the help of available non-expensive materials using comprehended studies done previously. Such type of indicators is mainly found to be used by steam and diesel engine manufacturers to enable them to work out horsepower ratings for the products. They are also a useful diagnostic tool to show problems with injection, valves, leaking piston rings etc. The engine indicator work on the principle of showing cylinder pressure plotted against piston movement (indicator diagram), and the resulting trace is marked onto a piece of treated paper to give a permanent record. The pressure is taken from the cylinder on test into the indicator. The indicator has a small cylinder with a piston which operates against a spring which sets the operating range. The indicator diagram is very important to know the combustion in the cylinder and also to adjust the engine. The diagram is taken periodically from the indicator valve equipped on the cylinder head and combustion condition is to be confirmed. The compression pressure and maximum pressure in the cylinder can be presumed from the indicator diagram. Engine indicator is the device used to take the indicator diagram, which can be considered as a ‘stethoscope’ for diesel engines. This diagram give efficiency of combustion in the cylinder, condition of the running gear, irregularities in fuel pumping and injection and a lot of things. The present work is aimed at learning the principle working of an actual indicator diagram and thereby designing and fabricating a low cost prototype engine indicator.