Internal-combustion engine with variable actuation of the intake valves and self-adaptive control of the air-fuel ratio with supervision of the control functions

Abstract

An internal-combustion engine for motor vehicles, for example a petrol-fuelled engine or a gas-fuelled engine, is provided with an electronically controlled hydraulic system for variable actuation of the intake valves. The system of variable actuation of the intake valves is governed by an electronic control unit that is programmed for performing at least once, at the start of the life of the engine, an activity of supervision of the functions of self-adaptive control of the air-fuel ratio. The supervision activity is based upon identification of a constant ratio between a delta in the value of the crank angle used by the electronic control unit and the error in the estimation of the air-fuel ratio by the electronic control unit when the system of actuation of the intake valves operates in late-opening mode. The activity of supervision envisages that the electronic control unit detects and stores the variation in the value of the crank angle (crank-angle delta) that must be applied to the value of the crank angle used by the electronic control unit in order to reach an estimated value of the mass of air taken in that basically coincides with the real value.