Wankel engine

German engineer Felix Wankel develops the prototype for his Wankel engine, a rotai y-piston engine. 

Diesel engine has little prospect of attaining an emission of NO below 1.0 g/mile. The inherently lean exhaust from Diesel makes an NO reduction catalyst useless, and would require an NO decomposition catalyst. The Wankel engine and the Honda stratified charge engine are also unable to reduce its NO emission below 1.0 g/mile. 

The four-stroke and two-stroke engines described above both use the slider-crank mechanism to transform piston work into crankshaft torque, but other intermittent-combustion engines have been conceived that use different kinematic arrangements to achieve this end. The only one that has realized significant commercial success is the rotary engine first demonstrated successfully in Germany by Felix Wankel in 1957. 

Internal combustion engines implementing the Otto cycle have been studied based on the rotary engine with a triangular rotor (Wankel), as well as free and spring loaded linear pistons. 

---