Torque control strategy for engines with continuously variable transmission

Abstract

A method and system for controlling torque disturbances in direct injection stratified charge and lean burn port-fuel injection engines (12) through continuously variable transmission (40). The method and system include using the continuously variable transmission (40) to mitigate the effects of torque disturbances due to a lean NOx trap (22) purge cycle (100). The continuously variable transmission (40) is coordinated with other engine variables, such as throttle (36), fueling rate (Wf), injection timing (γ), and spark timing (δ), to keep the operation near the optimal regime. In periods of trap (22) purge, the engine control variables and the continuously variable transmission (40) are coordinated to maximize purge efficiency for a predetermined period of time. In periods of normal operation (102), the engine control variables and the continuously variable transmission (40) are coordinated to minimize fuel consumption subject to emission constraints.

Dependencies are inferred from the claim text.