Working of Two Stroke Petrol Engine

In this post you will learn the functioning of two stroke petrol engine.

In the figure various parts have been marked such as piston, inlet port,outlet(exhaust) port,crankcase,etc.

Working:-

1)The piston moves up from bottom dead center (BDC) to top dead center (TDC). Both the transfer and exhaust ports covered by the piston. Air fuel mixture from carburetor is transferred already into engine cylinder is compressed by the moving piston. The pressure and temperature increases at the end of compression.

(pic from mechlook.com)

2)As the piston reaches the TDC the charge ignited by means of electric spark provided by the spark plug. At the same time the piston uncovers inlet port and fresh charge enters the crankcase as shown in Figure

3)The gases expands in the cylinder due to its combustion and thus the piston moves down, hence useful work is obtained. During this movement charge in the crankcase is partially compressed and this is known as crank case compression.

4)At the end of expansion, exhaust port is uncovered. The burnt gases escape to atmosphere, during this time the transfer port is also open. The partially compressed charge from crankcase enters to the cylinder through transfer port. The special shape provides the cycle reduce the escape of fresh charge along with the burned product.

Again the piston moves up, the transfer port is first closed and then exhaust port is closed. The compression of charge takes place inside the cylinder. When it reaching TDC the inlet port uncovered and low pressure is created to bring fresh charge to crank case. After compression, the ignition of charge take place and the cycle is repeated. All the events are completed in two strokes of the piston and the crankshaft makes one resolution.

hope it is clear enough to be assimilated easily.

your suggestions will be highly appreciated.
afzal
http://afzal-allaboutautomobiles.blogspot.com/