To meet the future challenges of reducing fuel consumption and exhaust emissions, load and speed dependent control of mixture formation and the combustion process are necessary. Although variable intake systems will contribute to this issue, current designs are characterized by costly deactivation mechanisms and have sensitivity to production tolerances.
In this paper, a new type of variable intake and mixture formation system is presented, which offers a new, economical and reliable way to control mixture formation and charge motion. A theoretical analysis was done to determine the best geometric dimensions and subsequent experimental results demonstrated the best potential strategies for reducing fuel consumption and exhaust emissions through improvements in lean burn capability and EGR-tolerance.
Compared to conventional port deactivation systems, all control features have been realized with a reduced number of required parts. Fexible mixture formation is achieved with a combination of single point (SPI) and multi point (MPI) injection which, in combination with a novel deactivation method, provides the potential for a high level of EGR tolerance as well as lean burn capability.