1. Rotary Engines

2. 13.1 Introduction
In 1924, when Felix Wankel, at the age of 22, began developing his rotary engine, nothing practical had yet been achieved. Wankel researched and analyzed the possibilities of various types of rotary engines and reached the optimum shape of the trochoid housing. In partnership with motorcycle manufacturer NSU, Wankel’s years of research and development finally culminated in the first Wankel-type DKM rotary engine, in The DKM proved that the rotary engine was not just a dream.
** Rotary engines don't have the cycle of up-down piston movements that normal engines have. Instead, rotary engines depend on a circular motion.
The most famous producer of these types of engine:
Mercedes 111. Stopped re-production.
NSU-Rover. Stopped re-production.
Mazda, still successfully producing these type of engines, and the most famous models are Cosmo Sport, and other models are under the name of RX 2, 3, 4, 5 stopped re-product. RX 7 and 8 still successful product and challenging the best cars which powered by ordinary engines.
13.2 Components
1. Rotor 2.Housing 3. Output shaft

3. 13.3Principle of Operation
As the rotor moves through the housing, the three chambers created by the rotor change size. This size change produces a pumping action.
Rotary engines use the four-stroke combustion cycle, which is the same cycle that four-stroke piston engines use. But in a rotary engine, this is accomplished in a completely different way.
The heart of a rotary engine is the rotor. This is roughly the equivalent of the pistons in a piston engine. The rotor is mounted on a large circular lobe on the output shaft. This lobe is offset from the centerline of the shaft and acts like the crank handle on a winch, giving the rotor the leverage it needs to turn the output shaft. As the rotor orbits inside the housing, it pushes the lobe around in tight circles, turning three times for every one revolution of the rotor.
Let's go through each of the four strokes of the engine looking at one face of the rotor.
Intake : intake phase of the cycle starts when the tip of the rotor passes the intake port. At the moment when the intake port is exposed to the chamber, the volume of that chamber is close to its minimum. As the rotor moves past the intake port, the volume of the chamber expands, drawing the air/fuel mixture into the chamber. When the peak of the rotor passes the intake port, that chamber is sealed off and compression begins.