In order to solve the problem of insufficient power of a turbocharged direct injection engine with the Atkinson cycle

appropriate rates of the Atkinson cycle were selected together with high geometric compression ratio and wide-adjustable variable valve timing (VVT) mechanism to reduce fuel consumption at part load while maintaining power performance at high load. By making prototype and bench test

the influences of the Atkinson cycle on the air exchange process

effect of fuel economy

emissions and power performance of the engine were studied. The results show that the engine with the Atkinson cycle can tolerate a higher geometric compression ratio to improve thermal efficiency. The Atkinson cycle is also helpful to reduce pumping loss at part load

improve combustion stability at low load

and reduce fuel consumption and particulate matter emissions as well as knock tendency at high load. But delayed intake valve closing will seriously affect engine power performance

so it is necessary to reduce the Atkinson cycle rate at high load and increase boost pressure.