Valves Event Control Strategy for Transient Operation of a CAI Engine equipped with 4VVAS

摘要

In this paper, a fully variable valve actuating system called as 4VVAS is put forward to realize transient and mode switch operation for a gasoline CAI engine based on internal EGR. 4VVAS, which is made up of two sets of valvetronic actuators and two sets of Vanous actuators, can independently and flexibly control intake valve lift, exhaust valve lift, intake valve tinning and exhaust valve timing.Through the research on the simulation and experiment, transient response of the CAI engine to change in the four control variables of 4VVAS are examined respectively, and effects on CAI combustion transition of the four actuators response time constants are investigated and compared. It is found that, in order to realize fast transition operation in CAI mode, appropriate coordinated and synchronous operation of the four actuators is required. The experimental results show that, during coupling regulation of the four variables, symmetric principle of valve timing and synchronal principle of valve lift are proposed to simplify coupling strategy and improve IMEP transition. The results will form the foundation of transient control strategy for the CAI engine based on the 4VVAS.