The Wankle Rotary Internal Combustion Engine FAQ

The WRCE, or just plain rotary, was developed by Dr. Felix Wankel earlier this century. It is based on the Otto cycle (intake, compression, power, exhaust) just like a typical reciprocating piston engine, however, it uses no valves, camshafts, cylinder heads, or timing belts.

The typical twin-rotor engine has 8 basic parts: a front, middle, and rear housing (called side housings), two rotor housings, two rotors, and an eccentric shaft. There are numerous other systems, but since they are similar to their piston engine counterparts, I won't go into detail about them. Basically, the front, middle, and rear housings "sandwich" the rotor housings, with the eccentric shaft in the middle. The front and rear housings employ main bearings to support the shaft, and each rotor has a bearing as well.

It is the matter in which the rotors drive the eccentric shaft that is unique, and odd. The rotor follows an epitrochoid curve. In layman's terms, the rotor "tumbles" over and over. It has a large gear that locks on to a smaller stationary gear that is part of the main bearing assembly. Through a combination of gears and eccentric shaft, the rotor is forced to tumble in its chamber. This, in turn, creates three seperate combustion chambers. During the tumbling, each chamber performs the basic otto-cycle functions. There are ports for intake built into the side housings, and as these are uncovered, the air / fuel mixture is sucked into the small chamber. As it continues, the rotor compresses the mixture, and moves it to the combustion location, where two spark plugs (leading and trailing) ignite the mixture. The combustion pushes the rotor until it is expelled via an exhaust port directly in the rotor housing.