A system for controlling powertrain components to achieve fuel economy goals

摘要

A system for controlling a vehicle drivetrain in a fuel-efficient manner includes, in one embodiment, a control computer operable to determine a number of engine load/engine speed boundary conditions as functions of brake specific fuel consumption (BSFC) contours in relation to an engine output characteristics map and define therefrom an undesirable engine operation region U. As long as the engine is engaged with at least one of the gear ratios of the vehicle transmission, the control computer is operable to maintain or encourage engine operation outside of the region U. In another embodiment, the control computer is operable to define a contour from substantially zero engine load to substantially full engine load, wherein the contour preferably corresponds to a fuel-efficient path from no-load to full-load engine operating conditions. With change gear transmissions, the control computer is operable to control transmission shift points about the contour. With continuous variable transmissions, the control computer is operable to modify the effective gear ratio thereof to maintain engine operation on or about the contour. In either case, fuel efficient operation may be optimized.