Method for controlling a hybrid powertrain, a hybrid powertrain, and a vehicle comprising such a hybrid powertrain

A hybrid powertrain comprising:

• a combustion engine;
• an electric machine;
• a gearbox with an input shaft and an output shaft, wherein the combustion engine and the electric machine are connectable to the input shaft of the gearbox;
• a coupling device configured for connecting and disconnecting the combustion engine from the input shaft of the gearbox;
• and
• a control device configured to:
• disconnect the combustion engine from the input shaft of the gearbox via the coupling device;
• select a starting gear in the gearbox, wherein the starting gear is a gear having a lower gear ratio than a gear ratio at which the combustion engine's torque at idling speed is able to sufficiently rotate the input shaft of the gearbox;
• control the gearbox to engage the selected starting gear in the gearbox;
• while the combustion engine is idling and not connected to the input shaft of the gearbox, connect or ensure that the electric machine is connected to the input shaft of the gearbox and thereafter control the electric machine to generate a torque in the input shaft of the gearbox using the electric machine;
• control the electric machine to accelerate thereby accelerating rotation of the input shaft of the gearbox;
• and
• when the input shaft of the gearbox, in the selected starting gear, is rotating at substantially the same speed as a rotational speed of the combustion engine, control the coupling device to connect the combustion engine to the input shaft of the gearbox to thereafter drive the input shaft of the gearbox with torque from the combustion engine, whereby using the electric machine to drive the input shaft of the gearbox at the selected starting gear with the lower gear ratio up to a rotating speed of the combustion engine prior to connecting the combustion engine to the input shaft of the gear box thereby reduces a number of gear shifts required to bring the vehicle up to a selected speed.

A vehicle comprising a hybrid powertrain comprising:

• a combustion engine;
• an electric machine;
• a gearbox with an input shaft and an output shaft, wherein the combustion engine and the electric machine are connectable to the input shaft of the gearbox;
• a coupling device configured for connecting and disconnecting the combustion engine from the input shaft of the gearbox;
• and
• a control device configured to:
• disconnect the combustion engine from the input shaft of the gearbox via the coupling device;
• select a starting gear in the gearbox, wherein the starting gear is a gear having a lower gear ratio than a gear ratio at which the combustion engine's torque at idling speed is able to sufficiently rotate the input shaft of the gearbox;
• control the gearbox to engage the selected starting gear in the gearbox;
• while the combustion engine is idling and not connected to the input shaft of the gearbox, connect or ensure that the electric machine is connected to the input shaft of the gearbox and thereafter control the electric machine to generate a torque in the input shaft of the gearbox using the electric machine;
• control the electric machine to accelerate thereby accelerating rotation of the input shaft of the gearbox;
• and
• when the input shaft of the gearbox, in the selected starting gear, is rotating at substantially the same speed as a rotational speed of the combustion engine, control the coupling device to connect the combustion engine to the input shaft of the gearbox to thereafter drive the input shaft of the gearbox with torque from the combustion engine, whereby using the electric machine to drive the input shaft of the gearbox at the selected starting gear with the lower gear ratio up to a rotating speed of the combustion engine prior to connecting the combustion engine to the input shaft of the gear box thereby reduces a number of gear shifts required to bring the vehicle up to a selected speed.

A computer program product comprising computer program code stored on a non-transitory computer-readable medium, said computer program product for controlling a hybrid powertrain, comprising a combustion engine, an electric machine, a gearbox with an input shaft and an output shaft, wherein the combustion engine and the electric machine are connectable to the input shaft of the gearbox, and a coupling device configured for connecting and disconnecting the combustion engine from the input shaft of the gearbox, said computer program product comprising computer instructions to cause said at least one control unit to perform the following operations:

• a) disconnect the combustion engine from the input shaft of the gearbox via the coupling device;
• b) select a starting gear in the gearbox, wherein the starting gear is a gear that comprises a lower gear ratio than a gear ratio at which the combustion engine's torque at idling speed is able to sufficiently rotate the input shaft of the gearbox;
• c) control the gearbox to engage the selected starting gear in the gearbox;
• d) while the combustion engine is idling and not connected to the input shaft of the gearbox, connect or ensure that the electric machine is connected to the input shaft of the gearbox and thereafter control the electric machine to generate a torque in the input shaft of the gearbox using the electric machine;
• e) control the electric machine to accelerate, thereby accelerating rotation of the input shaft of the gearbox;
• and
• f) when the input shaft of the gearbox, in the selected starting gear, is rotating at substantially the same speed as a rotational speed of the combustion engine, control the coupling device to connect the combustion engine to the input shaft of the gearbox to thereafter drive the input shaft of the gearbox with torque from the combustion engine, whereby using the electric machine to drive the input shaft of the gearbox at the selected starting gear with the lower gear ratio up to a rotating speed of the combustion engine prior to connecting the combustion engine to the input shaft of the gear box thereby reduces a number of gear shifts required to bring the vehicle up to a selected speed.