A Comparative Study on Influence of EIVC and LIVC on Fuel Economy of A TGDI Engine Part I: Friction Torques of Intake Cams with Different Profiles and Lifts
In order to better understand how the Atkinson cycle and the Miller cycle influence the fuel consumption at different engine speeds and loads, an investigation was conducted to compare influences of early intake valve closing (EIVC) and late intake valve closing (LIVC) on the fuel consumption of a 1.5L turbo-charged gasoline direct injection (TGDI) engine. The engine was tested with three different intake cams, covering three intake durations: 251 degCA (the base engine), 196 degCA (the Miller engine), and 274 degCA (the Atkinson engine). Compression ratios are 9.5:1 for the base engine and 11.4:1 for the Atkinson and Miller engines, achieved with piston modifications. Results of this investigation will be reported in three papers focusing respectively on characteristics of the engine friction, in-cylinder charge motions for different intake events, and combustion and fuel economy without and with EGR for the naturally aspirated mode and boost mode.