Method of reducing feed gas emissions in an internal combustion engine

Abstract

A method of reducing feed gas emissions and improving fuel economy in an internal combustion engine uses a variable cam timing mechanism and an electronically controlled throttle. The method includes: a) predetermining ranges of negligible torque demand, small torque demand, moderate torque demand, high torque demand and maximum torque demand; b) determining actual torque demand; c) using conventional cam phasing and pedal-to-throttle relationship if actual torque demand corresponds with the negligible torque demand range; d) using cam phasing of magnitude in transition between conventional and fully retarded cam phasing and retaining conventional pedal-to-throttle relationship if actual torque demand corresponds with the small torque demand range; e) using fully retarded cam phasing and electronically adjusting throttle position to meet actual torque demand if actual torque demand corresponds with the moderate torque demand range; f) using cam phasing of magnitude in transition between fully retarded and conventional cam phasing and holding throttle position constant if actual torque corresponds with the high torque demand range; and g) using conventional cam phasing and pedal-to-throttle relationship if actual torque corresponds with the maximum torque demand range. Similar schemes are provided for intake advance and exhaust retard strategies.