Method for controlling with adaptivity a wastegate in a turbocharged internal combustion engine

1. A method for controlling the wastegate ( 16 ) in a internal combustion engine ( 1 ) turbocharged by means of a turbocharger ( 12 ); the control method comprises the steps of:

determining an objective supercharging pressure (P obj );

measuring an actual supercharging pressure (P);

determining a second closed loop contribution (WG CL1 ) of an objective position (WG obj ) of a controlling actuator ( 35 ) of the wastegate ( 16 );

determining a third adaptive contribution (WG A ) of the objective position (WG obj ) of the controlling actuator ( 35 ) of the wastegate ( 16 );

calculating the objective position (WG obj ) of the controlling actuator ( 35 ) of the wastegate ( 16 ) by adding the two contributions (WG OL , WG CL1 );

controlling the controlling actuator ( 35 ) of the wastegate ( 16 ), so as to pursue the objective position (WG obj ) of the controlling actuator ( 35 ) of the wastegate ( 16 );

determining, during a design phase, a control law (CL) which provides an objective opening of a controlling actuator ( 35 ) of the wastegate ( 16 ) according to the supercharging pressure (P);

determining a first open loop contribution (WG OL ) of an objective position (WG obj ) of the controlling actuator ( 35 ) of the wastegate ( 16 ) through the control law (CL) and according to the objective supercharging pressure (P obj ); and

calculating the objective position (WG obj ) of the controlling actuator ( 35 ) of the wastegate ( 16 ) by adding the three contributions (WG OL , WG CL1 , WG A ).

2. The control method as set forth in claim 1 further including the steps of:

storing the third adaptive contribution (WG A ) in a memory ( 47 ); and

updating the third adaptive contribution (WG A ) stored in the memory ( 47 ) when the turbocharger ( 12 ) is in a stabilized running condition and using an integral term of the second regulator ( 45 ) and/or of the first regulator ( 44 ).

3. The control method as set forth in claim 2 further including the steps of:

determining a weight (W); and

updating the third adaptive contribution (WG A ), when the turbocharger ( 12 ) is in a stabilized running condition, using the integral term of the second regulator ( 45 ) and/or of the first regulator ( 44 ) weighed by means of the weight (W).

4. The control method as set forth in claim 3 further including the step of determining the weight (W) according to an actual position of the controlling actuator ( 35 ) of the wastegate ( 16 ), so that the weight (W) is minimum when the hysteresis in the control of wastegate ( 16 ) is maximum.

5. The control method as set forth in claim 1 , wherein the third adaptive contribution (WG A ) is variable according to a reduced mass flow rate (M R ) of the supercharger ( 14 ) and to a supercharging ratio (RP) which is equal to the ratio between the supercharging pressure (P) and the atmospheric pressure (P atm ).

6. The control method as set forth in claim 1 further including the step of filtering the third adaptive contribution (WG A ) by means of a second first-order low-pass filter ( 48 ) in order to reduce the variation rapidity.

7. The control method as set forth in claim 1 further including the step of filtering the objective supercharging pressure (P obj ) by means of a first first-order low-pass filter ( 38 , 46 ) in order to reduce the variation rapidity.

8. The control method as set forth in claim 7 further including the step of determining a cutoff frequency of the first low-pass filter ( 38 , 46 ) according to a reduced mass flow rate (M R ) of the supercharger ( 14 ) and to a supercharging ratio (RP) which is equal to the ratio between the supercharging pressure (P) and the atmospheric pressure (P atm ) or according to a rotation speed of the internal combustion engine ( 1 ) and according to a gear engaged in a transmission which receives motion from the internal combustion engine ( 1 ).