The Wankel engine is a form of heat engine that has a rotary piston.In other words,instead of going up and down the Wankel piston rotates in the cylinder.Boht cylinder and piston are quite different in shape from those of conventional engines. The Wankel piston is tringular with curved sides, the cylinder is roughly oval in shape. The piston has an inner dore which is liked through an eccentrik gear to the output shaft. The other end of the dore is toothed and engaged with a stationary gear fixed to the cylinder end. Their arrangement ensures that the piston follows an elliptical path round the cylinder so that the apexes of the piston, which carry gastight seals, are always in contact with the inside surface of the cylinder
The piston thus forms thrree crescent-shaped spaces between itself and the cylinder wall, which vary in size as the piston rotates. Fuel enters the cylinder through the inlet port when one of these spaces is increasing in size. The fuel trapped in this section is then compressed by the turning piston and ignited by the sparking plug. The expanding gases subject the piston to a twisting moment which makes the piston revolve further until the exhaust gases escape through the exhaust port. A fresh charge is then induced into the cylinder. Meanwhile the same process is being repeated in the other two spaces between the piston and the cylinder.
The Wankel engine has many advantages over the reciprocating piston engine. Fewer moving parts are necessary because it produces a rotary movement using a connecting rod and a crankshaft. Because of this rotary movement it has vibration. In addition it has no valves, it is smaller and lighter than conventional engines of the same power, and it runs economically on diesel and several other fuels.