Wankel engine

The Wankel rotary engine is a type of internal combustion engine, invented by German engineer Felix Wankel, which uses a rotor instead of reciprocating pistons. This design promises smooth high-rpm power from a compact, lightweight engine; however Wankel engines are criticized for poor fuel efficiency and exhaust emissions.

Advantages

Wankel engines have several major advantages over reciprocating piston designs, in addition to having higher output for similar displacement and physical size. Wankel engines are considerably simpler and contain far fewer moving parts. For instance, because valving is accomplished by simple ports cut into the walls of the rotor housing, they have no valves or complex valve trains; in addition, since the rotor is geared directly to the output shaft, there is no need for connecting rods, a conventional crankshaft, crankshaft balance weights, etc. The elimination of these parts not only makes a Wankel engine much lighter (typically half that of a conventional engine with equivalent power), but it also completely eliminates the reciprocating mass of a piston engine with its internal strain and inherent vibration due to repetitious acceleration and deceleration, producing not only a smoother flow of power but also the ability to produce more power by running at higher rpm.

Related Topics:
Valves or complex valve trains - Connecting rod - Crankshaft - Crankshaft balance weight - Piston engine - Acceleration - Deceleration - Rpm

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In addition to the enhanced reliability due to the elimination of this reciprocating strain on internal parts, the construction of the engine, with an iron rotor within a housing made of aluminum which has greater thermal expansion, ensures that even when grossly overheated the Wankel engine will not seize, as an overheated piston engine is likely to do; this has substantial benefit for aircraft use.

Related Topics:
Iron - Aluminum - Thermal expansion

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The simplicity of design and smaller size of the Wankel engine also allow for a savings in construction costs, compared to piston engines of comparable power output.

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As another advantage, the shape of the Wankel combustion chamber and the turbulence induced by the moving rotor prevent localized hot spots from forming, thereby allowing the use of fuel of very low octane number without preignition or detonation, a particular advantage for Hydrogen cars. This feature also led to a great deal of interest in the Soviet Union, where high octane gasoline was rare.

Related Topics:
Fuel - Octane number - Preignition or detonation - Hydrogen car - Soviet Union

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