Wankel engine definition
A rotary internal combustion engine invented by Felix Wankel. It consists of an equilateral triangular member with curved sides orbiting about an eccentric on a shaft inside a stationary housing whose inner working surface is in the shape of an epitrochoid . The rotor is in sliding contact with the eccentric and imparts power to the eccentric shaft as a connecting rod does to a crankshaft . With one-third of a rotor revolution per shaft revolution and a power impulse for each of the three rotor sides, the Wankel generates one power impulse per revolution per rotor--twice that of what the four-cycle piston engine produces. Thus it has become accepted practice to multiply the geometry displacement of the Wankel by a factor of two for comparison with otto-cycle piston engines. The Wankel's advantages include compact size, light weight and smooth operation because there are no reciprocating parts. Its drawbacks include relatively high exhaust emission , possible sealing problems and low fuel economy . Mazda, however, has made significant improvements in all three areas.