METHOD FOR CONTROLLING A MOTOR-VEHICLE PROVIDED WITH A PROPULSION SYSTEM OF THE "MILD-HYBRID" TYPE

摘要

In a vehicle provided with a power propulsion system of the mild-hybrid type, a BAS unit —including an electric machine connected through a belt transmission to the shaft of an internal combustion engine—is exploited as the only propulsion engine of the vehicle in given operating conditions. The internal combustion engine is provided with a system for variable actuation of the intake valves which is controlled to reduce the pumping losses of the internal combustion engine in the phase in which such engine is in cut-off condition and it is driven by the aforementioned BAS unit. It is also provided for that the system for variable actuation of the intake valves be controlled to temporarily increase the pumping losses of the internal combustion engine in a phase in which it is required to accelerate the switching off of the engine.

主权项

1. Method for controlling a motor vehicle of the type comprising:
an internal combustion engine having a drive shaft with an output end connected through a transmission to at least one pair of wheels of the motor vehicle and an upstream end connected to one or more auxiliary devices through a belt transmission, a BAS unit comprising an electric machine connected to said upstream end of the drive shaft through said belt transmission and controlled to operate as an electrical power generator, as an electric motor for starting the internal combustion engine and as an auxiliary engine for the propulsion of the motor vehicle, additionally to the internal combustion engine, wherein: in given engine operating conditions said BAS unit is used as the only propulsion engine of the motor vehicle, maintaining the internal combustion engine in a cut-off condition and using the drive shaft as a simple transmission shaft, said internal combustion engine is provided with a system for variable actuation of the intake valves, and in the aforementioned operating conditions wherein the BAS unit used as the only propulsion engine, the system for variable actuation of the intake valves of the internal combustion engine is controlled to vary the opening time and/or the closing time and/or the lift of the intake valves, so as to reduce the losses due to a pumping effect which occur within the internal combustion engine when it is driven in rotation by said BAS unit in a cut-off condition.