- An idealized reversible cycle of four operations occurring in a perfect four-stroke petrol engine. These are:
- constant volume temperature rise
- constant pressure expansion
- constant volume temperature fall
- constant pressure volume decrease
- The cycle returns the gas to it's original state.
The otto cycle is more efficient than the diesel for equal compression ratios, but the compression ratio is limited due to spontaneous ignition of the fuel at higher temperatures.
Invented by Beau de Rochas in 1862 and applied by Dr. Otto in 1877 in the Otto-Crossley gas engine, the first commercially successful internal combustion engine.