The Quasiturbine, is a new concept (patented 10 years ago), that promises to revolutionize the internal combustion engine. It is said to make engines more efficient, quieter and much lighter for the same torque and horsepower abilities. It also promises to make for better compressors and pneumatic motors (refrigeration, heat pumps, stirling engines, steam turbines). The Quasiturbine or Qurbine engine is a pistonless rotary engine using a four-sided rhomboid rotor whose sides are hinged at the vertices. For more details see this explanation of how the Quasiturbine works.
Patents for the Quasiturbine are held by the Saint-Hilaire family of Quebec. As well as an internal combustion engine, the Quasiturbine has been proposed as a possible pump design, and demonstrated as a pneumatic engine using stored compressed air and as a steam engine.