Wankel Engines

The wankel engine uses a curved triangle within an almost "8-shaped" chamber to create chambers of compression. The internal shaft (A, see animation on the right) rotates three times to every one cycle of the rotor (B, refer to animation).

Inside a Wankel Engine

These engines do not require valves, because the intake and exhaust chambers are always open. Although they are mechanically simple, these engines are rarely mass-produced due to reliability issues that can result from poor geometrical engineering. Currently, the only auto manufacturer to mass-produce this engine is Mazda, in models such as the RX-7 and RX-8. The engine has found its way into other applications, often due to its impressive power-to-weight ratio.

Images courtesy of Wikimedia Commons.