Abstract
Homogeneous charge compression ignition (HCCI) engine can decrease both NO_x and PM. However, it is difficult to control the ignition timing and the operating range is limited by knocking. The objective of this study was to increase indicated mean effective pressure (IMEP) of HCCI engine by energy accumulated type variable valve timing (EAVVT) system and supercharger. A numerical calculation based on an elementary chemical reaction model was conducted to estimate the effect of intake valve close (IVC) timing and supercharging on HCCI combustion. As a result, maximum IMEP increased from 0.32MPa to 0.51 MPa due to increase supplied energy without knocking. The reasons of increase supplied energy were that equivalence ratio decreased with supercharging, and that most mixtures were burnt at the expansion stroke with IVC timing control.
