Marine 2 Stroke Engine Mainly Works on the principle of Dual which is the Combine of Diesel Cycle and Otto Cycle. The Two Stroke engine is mainly used for the propulsion of the Ship. The Crankshaft Bearings are lubricated by the presurrised oil.
To Complete one cycle the crank must revolve ones. Basically the Two stroke engine have the ports, they dont have valve. But nowdays the latest Engine have the Exhuast valve to increase the efficiency of the engine.
Here 2-Stroke means :- Piston going up and then going Down. In which ones a compression and once expansion with one power stroke in one cycle.
First Stroke :-
The first stroke is also known as compression stroke. In the first stroke the Piston moves from BDC(Bottom Dead Centre) to the TDC(Top Dead Centre). Due to this the crankshaft will rotates Half. As the piston moves upward the air into the compression the chamber will compressed.The crankshaft is revolving clockwise and the piston is moving up the cylinder, compressing the air. Due to the compresssion the pressure of air and temperature is incresed. Due to the compression pressure incresed upto 35 to 45 bar corresponding increase in temperature upto 650 to 850 degree celcuis.
Before reaching the TDC the Fuel is injected with the help of Fuel Injector. The fuel injection and the inlet and outlet valve opens and closing is Depend of the VALVE TIMING DIAGRAM. The Fuel is atomised into the fuel injector and inject through the nozzle. Due to large contact area the fuel is catches fire.
Second Stroke :-
This stroke is also known as Power Stroke or Expansion stroke. After Combustion the extra ordinary pressure and temperature is created. This extra extra ordinary pressure creates the expasion due to which the piston moves downward due to which the crank rotates. As the piston moves down the exhaust port or exhaust valvce opens and the unwanted air is removed form the combustion chamber. After this the piston reaches to the BDC and the cycle keep going on.