A powertrain comprising a transmission (2), a first electric motor (4a) and a second electric motor (4b), the transmission having an input shaft (1) to which a source of mechanical power may be connected, an output shaft (6) and a gear assembly providing at least two different gear ratios that may be selected for transfer of mechanical power from the input shaft (1) to the output shaft (6), the first electric motor (4a) is connected to the input shaft (1), such that torque and rotation may be transferred between the first electric motor and the input shaft, and the second electric motor (4b) is connected to the input shaft (1) via a first clutch (5a), such that torque and rotation may be transferred between the second electric motor (4b) and the input shaft (1), and connected to the output shaft (6) via a second clutch (5b), such that torque and rotation may be transferred between the second electric motor (4b) and the output shaft (6), wherein the first electric motor (4a) is connected to the second electric motor (4b) via the first clutch (5a).

A method for operating a dual-clutch transmission includes, to resolve a respective tooth-on-tooth position between a toothing of a sliding sleeve and a toothing of a gear wheel during an engaging operation for the respective gear, a relative rotation between the toothing of the sliding sleeve and the toothing of the gear wheel is effected by a twisting torque which acts on the respective gear where the twisting torque is a same size for all of the plurality of gears.

Methods and system are described for changing a driveline gear range from a lower gear range to a higher gear range. The driveline may include two electric machines and four clutches in a four wheel drive configuration. The methods and systems permit a driveline to change from a lower gear range to a higher gear range in a way that may reduce torque disturbances that may result from gear lash.

A 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, comprising the steps of: opening, in a first instant, an outgoing clutch; closing, in the first instant, an incoming clutch; synchronizing, between a second instant and a third instant, a rotation speed of the internal combustion engine with a rotation speed of the incoming clutch, namely with the rotation speed imposed by the gear ratio of the following gear; completely opening, in the third instant, the outgoing clutch; completely closing, in the third instant, the incoming clutch; keeping the torque transmitted by the outgoing clutch constant between the second instant and a fourth instant; and keeping the torque transmitted by the incoming clutch constant between the second instant and the fourth instant.

A method for operating a dual-clutch transmission includes, to resolve a respective tooth-on-tooth position between a toothing of a sliding sleeve and a toothing of a gear wheel during an engaging operation for the respective gear, a relative rotation between the toothing of the sliding sleeve and the toothing of the gear wheel is effected by a twisting torque which acts on the respective gear where the twisting torque is a same size for all of the plurality of gears.

Methods and system are described for changing a driveline gear range from a lower gear range to a higher gear range. The driveline may include two electric machines and four clutches in a four wheel drive configuration. The methods and systems permit a driveline to change from a lower gear range to a higher gear range in a way that may reduce torque disturbances that may result from gear lash.

The present invention provides a powertrain comprising a transmission (2), a first electric motor (4a) and a second electric motor (4b), wherein the transmission comprises an input shaft (1) to which a source of mechanical power may be connected, an output shaft (6) and a gear assembly providing at least two different gear ratios that may be selected for transfer of mechanical power from the input shaft (1) to the output shaft (6), the first electric motor (4a) is connected to the input shaft (1), such that torque and rotation may be transferred between the first electric motor and the input shaft, and the second electric motor (4b) is connected to the input shaft (1) via a first clutch (5a), such that torque and rotation may be transferred between the second electric motor (4b) and the input shaft (1), and connected to the output shaft (6) via a second clutch (5b), such that torque and rotation may be transferred between the second electric motor (4b) and the output shaft (6), wherein the first electric motor (4a) is connected to the second electric motor (4b) via the first clutch (5a).

A vehicle has an engine (1) as a driving source. Output rotation of the engine (1) is transmitted to driving wheels (7) through a torque converter (2) equipped with a lock-up clutch, a first gear train (3), a transmission (4) formed by combination of a variator (20) and an auxiliary transmission (30), a second gear train (5) and a final speed reduction device (6). The second gear train (5) is provided with a parking mechanism (8) that mechanically locks an output shaft of the transmission (4) so that the output shaft of the transmission (4) cannot rotate during parking of the vehicle. A shift speed when down-shift is performed by the variator (20) during a torque-down request to the engine (1) is set to be slower than a shift speed when down-shift is performed by the variator (20) during a non-torque-down request.

A 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, comprising the steps of: opening, in a first instant, an outgoing clutch; closing, in the first instant, an incoming clutch; synchronizing, between a second instant and a third instant, a rotation speed of the internal combustion engine with a rotation speed of the incoming clutch, namely with the rotation speed imposed by the gear ratio of the following gear; completely opening, in the third instant, the outgoing clutch; completely closing, in the third instant, the incoming clutch; keeping the torque transmitted by the outgoing clutch constant between the second instant and a fourth instant; and keeping the torque transmitted by the incoming clutch constant between the second instant and the fourth instant.

A vehicle has an engine (1) as a driving source. Output rotation of the engine (1) is transmitted to driving wheels (7) through a torque converter (2) equipped with a lock-up clutch, a first gear train (3), a transmission (4) formed by combination of a variator (20) and an auxiliary transmission (30), a second gear train (5) and a final speed reduction device (6). The second gear train (5) is provided with a parking mechanism (8) that mechanically locks an output shaft of the transmission (4) so that the output shaft of the transmission (4) cannot rotate during parking of the vehicle. A shift speed when down-shift is performed by the variator (20) during a torque-down request to the engine (1) is set to be slower than a shift speed when down-shift is performed by the variator (20) during a non-torque-down request.