The first Wankel engine was first developed by a German engineer named Felix Wankel in 1929. Now the Modern Engine was addpoted designed by Hanns Dieter Paschke.

In piston engine, the rotary engine uses the pressure created when a combination of air and fuel is burned. When the Fuel Burned the high temperature and pressure gases are produce and these pressure is contained in the cylinders and forces pistons to move back and forth. Then the piston which are moving back and forth are transmit the power to connecting rods and crankshaft which convert the reciprocating motion of the pistons into rotational motion that can be used to power a car.
Where as in case of rotary engine, instead of pistons the pressure of combustion is contained in a chamber formed by part of the housing and sealed in by one face of the triangular rotor incorporating a central ring gear is driven around a fixed pinion within an oblong chamber.The rotor has three convex faces which acts like a piston.
The rotary motion is transferred to the drive shaft by an eccentric wheel that rides in a matching bearing in the rotor. The drive shaft rotates once during every power stroke instead of twice as in the Otto cycle.