Method and Control System for Operating a Drive Train

A method for operating a drive train of a motor vehicle, the drive train comprising a prime mover (1) with an internal combustion engine (2) and an electric machine (3), a separating clutch (6) connected between the internal combustion engine (2) and the electric machine (3), and a transmission (5) connected between the prime mover (1) and a driven end (4), the method comprising:

• in response to at least one first defined operating condition, coupling a previously decoupled internal combustion engine (2) by actuating the separating clutch (6) to engage;
• in response to at least one second defined operating condition, aborting the coupling of the internal combustion engine (2) by actuating the separating clutch (6) to disengage;
• and
• determining an absolute value of a torque currently transmitted or currently transmittable by the separating clutch (6),
• wherein the separating clutch (6) is disengaged at different rates depending on the absolute value of the torque currently transmitted or currently transmittable by the separating clutch (6).

A control system for operating a drive train of a motor vehicle, comprising:

• an engine control unit (8) for open-loop control and/or closed-loop control of an internal combustion engine (2);
• a hybrid control unit (10) for open-loop control and/or closed-loop control of an electric machine (3);
• and
• a transmission control unit (9) for open-loop control and/or closed-loop control of a transmission (5),
• wherein the transmission control unit (9) or the hybrid control unit (10) actuates a separating clutch (6) to engage in order to couple a previously decoupled internal combustion engine (2) in response to at least one first defined operating condition, the separating clutch (6) connected between the internal combustion engine (2) and the electric machine (3),
• wherein the transmission control unit (9) or the hybrid control unit (10) aborts the coupling of the internal combustion engine (2) by actuating the separating clutch (6) to disengage in response to at least one second defined operating condition, the transmission control unit (9) or the hybrid control unit (10) also determining an absolute value of a torque currently transmitted or currently transmittable by the separating clutch (6), and
• wherein the transmission control unit (9) or the hybrid control unit (10) disengages the separating clutch (6) at different rates depending on the absolute value of the torque currently transmitted or currently transmittable by the separating clutch (6).