Abstract: The air/fuel ratio of the combustion mixture in the cylinders of an engine is sensed and the sensed air/fuel ratio is controlled to a predetermined scheduled air/fuel ratio by controlling the amount of exhaust gases recirculated. When the exhaust gas recirculated is substantially zero, the air/fuel ratio is thereafter closed loop adjusted to a predetermined scheduled minimum air/fuel ratio when the sensed air/fuel ratio is less than the minimum and when the sensed air/fuel ratio is greater than the minimum while the operator command is at a maximum to thereby provide precise fuel limiting at a predetermined fuel limit schedule.

Abstract: A dilution control adjusts an EGR valve, variable valve lift mechanism or similar dilution control device in an internal combustion engine in response to the relationship between ignition timing and the timing of peak combustion pressure (LPP) in the vicinity of a desired timing of peak combustion pressure (DLPP). The relationship is derived in the process of controlling ignition timing in response to LPP, wherein LPP is controlled to DLPP or as close to it as possible. In this process, LPP varies slightly back and forth through DLPP or through a maximum retard value, if LPP is not attainable. The apparatus detects whether LPP is retarded with respect to DLPP as it reverses from retard to advance, increases dilution if it is so retarded and decreases dilution if it is not. The engine thus operates with maximum EGR consistent with LPP being equal to the desired value DLPP.

Abstract: An internal combustion engine with a throttle valve, fuel supply and dilution (EGR) control includes apparatus effective to detect a throttle tipout condition comprising a rate of throttle closing exceeding a predetermined reference rate and decrease the dilution from the scheduled value to its minimum value during the existence of the throttle tipout condition and further apparatus effective to detect the end of the throttle tipout condition and return the dilution to its scheduled value at a controlled rate. Thus, a sudden unscheduled increase in dilution caused by a throttle tipout associated increase in intake manifold vacuum is reduced and driveability improved.

Abstract: An LPP ignition timing control for an internal combustion engine of the type having a normal combustion mode characterized by combustion pressure peaks compatible with closed loop LPP ignition timing control and an abnormal combustion mode which may not be so compatible includes a closed loop control apparatus effective to sense LPP in the combustion chamber, generate an LPP value therefrom, store a DLPP value indicative of a desired LPP, and compare the LPP value and stored DLPP value and adjust ignition timing to reduce the difference therebetween. During a sensed abnormal combustion mode, the control changes the ignition timings for ignition events toward predetermined, stored ignition timings and substitutes for the stored DLPP value temporary DLPP values which are a predetermined crankshaft angle in advance of the generated LPP values and limited in the retard direction to the stored DLPP value.

Abstract: An internal combustion rotary engine is disclosed having leading and trailing spark plugs with their respective spark electrodes arranged in peripherally spaced ignition openings in the inner peripheral wall of the engine's rotor housing. The leading ignition opening is located in a zone where the leading apex seal of the passing chambers experiences a relatively low pressure differential which decreases in the direction of rotor rotation whereas the trailing ignition opening is located in a zone where the trailing apex seal of the passing chambers also experiences a relatively low pressure differential but which increases in the direction of rotor rotation.