Method for controlling a hybrid drive train of a vehicle

Abstract

A method of controlling a hybrid drive-train of a vehicle in which the hybrid drive-train comprises a combustion engine having a driveshaft, an electric machine that can be connected to the driveshaft of the engine by a clutch, an automated transmission with an input which is connected to the rotor of the electric machine, and shifting elements for shifting between two gears. During electric driving operation with the engine stopped and the clutch disengaged, the engine can be drag-started in combination with a downshift in the transmission. Drag starting of the engine is carried out by disengaging the frictional shifting element to be disengaged to below a slipping limit, engaging the clutch until the engine reaches or exceeds its minimum starting speed, starting the engine self-starts, substantially disengaging the clutch, separately adjusting the engine and electric machine to the synchronous speed of the target gear, and fully engaging and disengaging associated shifting elements.

Description

technical field [0001] The invention relates to a method for controlling a hybrid powertrain of a motor vehicle, the hybrid powertrain comprising: an internal combustion engine with a drive shaft; an electric machine operable at least as a motor, the electric machine comprising a drive shaft that can be connected to the internal combustion engine via an automated separation clutch Connected rotors; automated powershift transmissions comprising an input element in driving connection with a rotor of an electric machine and comprising at least two friction shifting elements for temporally overlapping transitions between two transmission gears, In this case, during electric driving operation with the internal combustion engine switched off and the release clutch disengaged, the internal combustion engine is started in traction-start mode in conjunction with a downshift of the powershift transmission. Background technique [0002] Parallel-operating hybrid powertrains of the abov...

AI Technical Summary

Problems solved by technology

However, since the separating clutch is always continuously engaged during traction and high speed rotation of the internal combustion engine, the torque peaks and speed peaks arising from the adjustment process of the internal combustion engine and from the separating clutch are continuously transmitted to the rotor of the electric machine and are From this rotor, at least partially via the friction shifting element to be disconnected, it is guided into the powershift transmission, thereby reducing driving comfort and increasing wear on the gears and bearings of the powershift transmission

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