Wankel Engine
Soon after the invention of the conventional internal combustion engine, engineers realized that a tremendous savings in both weight and energy could be realized if the combustion of gasoline could be used to produce rotary motion directly instead of via the reciprocating action of the typical piston engine. The engineer who transformed this idea into a working rotary engine was Felix Wankel.
Felix Wankel was born in Germany at Lahr, a town near the French border, in 1902. During World War II he worked in the German Aeronautical Research Establishment researching rotary piston technology. After the war, he went to work for a German automotive firm. By 1957 he had built a prototype of his "Wankel" engine and received numerous patents, including several for the special tools needed to build the rotary engines.
The rotary-piston engine uses a triangular-shaped piston which revolves within an oval-shaped chamber that is slightly constricted in the middle. (This shape is called an epitrochoid.) One of the early major drawbacks of the rotary engine was the necessity of maintaining a perfect seal between the engine walls and the leading edges of the triangular rotor. Wankel designed a series of sprung sealing plates to solve this problem. The rotating triangular piston also serves to seal off the intake and exhaust ports, thus eliminating the need for valves.
The power of the ignited gasoline is transferred directly to the driveshaft through a series of gears in a three-to-one ratio. This design resulted in a motor that produces three power "strokes" per revolution, compared to only one power stroke per two revolutions of the typical four-stroke gasoline engine. Further efficiency and smoothness of operation can be achieved by building engines with more than one rotor. A three-rotor engine corresponds in power to an eight cylinder reciprocating engine.
The engine's major advantages when compared to conventional piston engines are its light weight, short length, efficient energy transfer, and insensitivity to grades of fuel burned. Also due to the rotary engine's lack of a crankshaft, camshaft, valves, and valve-train, it is much easier to maintain. However, its fuel consumption, manufacturing costs, and pollutant emission rates are above those of reciprocating piston engines.
The early dreams of seeing eight out of ten cars powered by the Wankel engine by the 1980s were not realized, yet the Wankel engine has been used by General Motors in the United States, Rolls-Royce in Great Britain, Alfa Romeo in Italy, Citroën in France, and Toyota in Japan. The Japanese Mazda Motor Corporation was the first to use the rotary engine in a production car in 1967, and Mazda continues to build automobiles with the rotary engine. General Motors, however, abandoned its plans for a rotary-powered vehicle in 1976 due to concerns over the engine's emissions problems. Several companies are actively researching the rotary engine's potential for use in the aircraft industry, where its small size and easy serviceability are decided advantages over bigger and more complicated gasoline engines.
Throughout his life, Felix Wankel continued to refine the engine that bears his name, heading his own research company at Lindau in Germany. He died in 1988.
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