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Variable valve actuation in heavy duty diesel engines is not well documented, partly because of diesel engine nature, such as, unthrottled air handling, which gives little room to improve pumping loss; a very high compression ratio, which makes the clearance between the piston and valve is little when the piston reaches the top dead center. It is a long time that diesel engines are running by EGR and VGT. The goal of this research work is addressed the issue about how much fuel benefit diesel engines at 13-mode cycle could be achieved using variable valve timing in a heavy duty diesel engine. Late inlet valve closing strategy will be used. In order to see how much fuel efficiency could improve in addition to EGR and VGT, EGR and VGT are fully controlled in a closed-loop. This paper examines fuel improvement in different speeds and torques. Finally, we could see that 3.28% BSFC benefit at 13-mode cycle could be achieved. The reason of this benefit is that fixed valve lift engine makes a compromise between high speed engine performance and low speed fuel economy, late inlet valve closing optimizes valve timing at each engine torque and speed.
Date of Conference: 27-31 March 2009