VVT+port deactivation application on a small displacement SI 4 cylinder 16V engine: An effective way to reduce vehicle fuel consumption

摘要

During recent years several VVT devices have been developed, in order to improve either peak power and low-end torque, or part-load fuel consumption of SI engines. This paper describes an experimental activity, concerning the integration of a continuously variable cam phaser (CVCP), together with an intake port deactivation device, on a small 4-cylinder 16V engine. The target was to achieve significantly lower fuel consumption under normal driving conditions, compared to a standard MPFI application. A single hydraulic cam phaser is used to shift both the intake and the exhaust cams to retarded positions, at constant overlap. Thus, high EGR rates in the combustion chamber and late intake valve closure ("reverse Miller cycle") are combined, in order to reduce pumping losses at part load. A specific port deactivation device, integrated into the intake manifold, is used to induce a swirl charge motion in the cylinder, so as to achieve good combustion stability with high EGR rate conditions. Using a 1.4 dm316V engine equipped with these devices, the concept was developed on the engine test bed with respect to functionality, durability, and cost. A demonstration car with this engine was prepared. ECU calibration was performed on the test bed and in the vehicle, with given targets for driveability and emissions. EURO 4 exhaust emission limits were considered, using a catalyst aged for 100,000 km. Fuel consumption was reduced by more than 6% in the NEDC cycle with this vehicle, compared to a standard (without any conventional EGR system) 4-cylinder 16V MPFI application.