Method to control the execution of a shift to a higher gear with a released accelerator pedal in a drivetrain provided with a dual-clutch, servo-assisted transmission

A method to control the execution of an upshift to a higher gear with a released accelerator pedal (22) in a drivetrain (6) provided with a dual-clutch, servo-assisted transmission (7), so as to upshift from a current gear (A) to a following gear (B), which is shorter than the current gear (A);

• the drivetrain (6) comprises the dual-clutch, servo-assisted transmission (7) having two primary shafts (15);
• at least one secondary shaft (17) connected to drive wheels (3);
• and two clutches (16A, 16B), each interposed between a drive shaft (5) of an internal combustion engine (4) and a corresponding primary shaft (15);
• the control method comprises the steps of:
• opening, in a first instant (t1), an outgoing clutch (16A) associated with the current gear (A);
• closing, in the first instant (t1), an incoming clutch (16B) associated with the following gear (B);
• synchronizing, between a second instant (t2), which is subsequent to the first instant (t1), and a third instant (t4), which is subsequent to the second instant (t2), a rotation speed (ωE) of the internal combustion engine (4) with a rotation speed (ωB) of the incoming clutch (16B), namely with the rotation speed (ωB) imposed by the gear ratio of the following gear (B);
• completely opening, in the third instant (t4), the outgoing clutch (16A);
• completely closing, in the third instant (t4), the incoming clutch (16B);
• keeping a torque (TA) transmitted by the outgoing clutch (16A) constant between the second instant (t2) and a fourth instant (t3), which is subsequent to the second instant (t2) and prior to the third instant (t4);
• and
• keeping a torque (TB) transmitted by the incoming clutch (16B) constant between the second instant (t2) and the fourth instant (t3).