Patent ID: 7699040

Claim:
A control method of a direct injection system ( 1 ) of the common-rail type provided with a shut-off valve ( 24 ) for controlling the flow rate of a high-pressure fuel pump ( 6 ); the control method comprising the steps of: feeding the pressurized fuel to a common rail ( 5 ) by means of a high-pressure pump ( 6 ) which receives the fuel through the shut-off valve ( 24 ); cyclically controlling the opening and closing of the shut-off valve ( 24 ) for choking the flow rate of fuel taken in by the high-pressure pump ( 6 ); adjusting the flow rate of fuel taken in by the high-pressure pump ( 6 ) by varying the ratio between the duration of the opening time and the duration of the closing time of the shut-off valve ( 24 ); and driving the shut-off valve ( 24 ) synchronously with respect to the mechanical actuation of the high-pressure pump ( 6 ) by means of a driving frequency of the shut-off valve ( 24 ) having a constant integer synchronization ratio, predetermined according to the pumping frequency of the high-pressure pump ( 6 ); the control method is characterized in that it comprises the further steps of: estimating a perturbation intensity (I) of the fuel pressure inside the common rail ( 5 ); and varying the phase of the commands of the shut-off valve ( 24 ) with respect to the phase of the mechanical actuation of the high-pressure pump ( 6 ) if the perturbation intensity (I) of the fuel pressure inside the common rail ( 5 ) is higher than a predetermined threshold value.