Abstract
Keywords: spark ignition engines, continuously variable transmissions, integrated powertrain control, driveability, fuel consumption
Abstract: In this study the authors consider a passenger car powertrain with spark ignition engine and continuously variable transmission. There have been done many road tests in order to get detailed knowledge about properties of the car equipped with the considered system. Influence of the powertrain control algorithm on traction properties, fuel consumption and pollutant emission has been investigated. On this basis, the authors have suggested an integrated control algorithm, based on fuzzy logic. It was assumed that the drivers pedal operation doesnt exactly determine the demanded drive torque or drive power. In his action only the changes of desired drive power finds expression. Such assumption increases the freedom in the choice of engine operating point. Free drive power course in transient process was added to free engine torque a speed value choice. So, although the proposed control algorithm transfers the powertrain with unceasingly ratio changes to the powertrain with infinite number of virtual gears, the engine operation point, in most of time , is kept on the best fuel efficiency operating line. The performance of the proposed integrated engine - transmission control algorithm is compared with that of conventional control. For a better quantitative verification, the drivability index has been formulated. It is has been proved that better drivability of a car can be achieved without fuel consumption increase.