Abstract: The invention relates to a control systems for feedback control of the air/fuel ratio in an internal combustion engine, e.g., an automotive engine, which uses a three-way catalyst to purify the exhaust gas, by using an exhaust sensor to detect actual values of air/fuel ratio in the engine. The control system has the function of varying the target value of air/fuel ratio according to operating conditions of the engine. The target value becomes super-stoichiometric during steady-state operation of the engine and changes to a lower value optimum for the activities of the three-way catalyst, such as the stoichiometric value, under predetermined transient conditions of the engine. At the start of such a change in the target value, the control system functions so as to intentionally deviate the air/fuel ratio from the value optimum for the three-way catalyst in a direction away from the target value immediately before the change.

Abstract: Routines are run which briefly monitor a selected parameter and ascertain, based on the magnitude of the parameter, the use of heavy, regular or light fuel. These routines set correction factor values which are used to modify fuel injection, ignition timing and the like, during transient modes of engine operation. Tables used in the identification are recorded in two-dimensional form. Following an identification and correction factor determination, the programs are adapted to terminate very early in the run. Depending on the change in fuel tank volume, previously obtained data is assumed to still hold true and analytical routines forshortened to obviate redundant re-analysis and lighten processor load.

Abstract: The amount of air being inducted into the cylinders of an internal combustion engine is detected and a signal indicative thereof is sampled at a predetermined intervals. The difference between two sampled values is used with the time required for a single induction phase to be carried out, to predict the total amount of air which will be inducted into each cylinder. Utilizing this approximation the amount of fuel which should be injected or otherwise supplied to the engine can be accurately determined and thus enable accurate real-time cycle to cycle A/F control.

Abstract: An air/fuel ratio sensor having a sensor section and a pump section, capable of accurately sensing air/fuel ratio and an air/fuel ratio detecting and controlling apparatus by utilizing the air/fuel ratio sensor in which the accuracy of air/fuel ratio detection and control can be improved by varying the number of cylinders into which fuel is injected in a multi-step manner, during engine deceleration while maintaining the amount of fuel injected into each cylinder at a constant level, by determining whether the air/fuel ratio sensor operation is normal or abnormal on the basis of the air/fuel ratio sensor output level when fuel injection is performed into all of the cylinders, the output sensor level when fuel injection is performed only into specific cylinders, and the sensor output level when fuel injection to all cylinders is halted.

Abstract: The invention relates to a control system for feedback control of the air/fuel ratio in an internal combustion engine which uses a three-way catalyst to purify the exhaust gas, and which may be an automotive engine, by using an exhaust sensor to detect actual values of air/fuel ratio in the engine. The control system has the function of varying the target value of air/fuel ratio according to operating conditions of the engine such that the target value becomes super-stoichiometric at least in a portion of a steady zone of the engine operating conditions. The control system includes means to detect the temperature of the three-way catalyst and means to vary the feed of fuel or air to the engine when the catalyst temperature is above a predetermined level, e.g. 750.degree. C., while the target value of the air/fuel ratio is super-stoichiometric such that the actual air/fuel ratio decreases to a predetermined value, e.g.

Abstract: The outputs generated by the throttle position sensor and the pressure responsive type air flow sensor (or alternatively a flap type air flow meter or the like) are used to generate correction factors which when combined permit the correction of the air flow sensor output for a short period following the initiation of a demand for engine acceleration to obviate the discrepency between the actual and indicated air flows and thus improve the real-time control of the air-fuel ratio (A/F) of the mixture and the level of emission control and performance of the engine.

Abstract: Improvements are made in a reciprocating-piston, four-stroke spark-ignition internal combustion engine of the type which has main and auxiliary combustion chambers and main and auxiliary intake valve associated respectively with the combustion chambers, wherein the auxiliary intake valve has a valve lift smaller than a valve lift of the main intake valve and wherein the duration of opening of the auxiliary intake valve is arranged to be shorter than that of the main intake valve for each of the intake strokes of the engine. The auxiliary intake stroke is preferably so operated as to start to open after the main intake valve has been opened and to fully close simultaneously as or before the main intake valve is fully closed.