Wankel rotary

The Wankel engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion. In contrast to the more common reciprocating piston designs, the Wankel engine delivers advantages of simplicity, smoothness, compactness, high revolutions per minute, and a high power-to-weight ratio primarily due to the fact that it produces three power pulses per rotor revolution compared to one per revolution in a two-stroke piston engine and one per two revolutions in a four-stroke piston engine (although at the actual output shaft, there is only one power pulse per revolution, since the output shaft spins three times as fast as the actual rotor does, as can be seen in the animation below, making it roughly equivalent to a 2-stroke engine of the same displacement; this is also why the displacement only measures one face of the rotor, since only one face is working for each outut shaft revolution). The engine is commonly referred to as a rotary engine, although this name also applies to other completely different designs, primarily aircraft engines with their cylinders arranged in a circular fashion around the crankshaft. All parts rotate consistently in one direction, as opposed to the common reciprocating piston engine, which has pistons violently changing direction. The four-stage cycle of intake, compression, ignition, and exhaust occur each revolution at each of the three rotor tips moving inside the oval-like epitrochoid-shaped housing, enabling the three power pulses per rotor revolution. The rotor is similar in shape to a Reuleaux triangle with sides that are somewhat flatter.

The design was conceived by German engineer Felix Wankel. Wankel received his first patent for the engine in 1929. He began development in the early 1950s at NSU, and completed a working prototype in 1957. NSU subsequently licensed the design to companies around the world, who have continually added improvements. The engines produced are of spark ignition, with compression ignition engines only in research projects.

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