Zf Friedrichshafen Ag

Magnus Stiefenhofer

Peter Schiele

Michael Sohler

Steffen Peine

Tobias Hartmann

A method for operating a drivetrain of a motor vehicle includes elevating a system pressure acting on a plurality of shift elements (A, B, C, D, E, F) when one of at least one positively locking shift element (A, F) is closed in a force-locking-free state, increasing a torque output by a drive assembly () and then subsequently reducing the torque output by the drive assembly () while the system pressure is elevated by an intervention with the drive assembly (), and reducing the system pressure after reducing the torque output by the drive assembly (). The one of the at least one positively locking shift element (A, F) closed in the force-locking-free state or another one of the at least one positively locking shift element (A, F) is opened while the system pressure is elevated and the torque output by the drive assembly () changes.

Method and control device for operating a transmission

A method for operating a vehicle drivetrain () includes decoupling, in the presence of a demand for realizing a sailing operating state of the vehicle drivetrain () during which a drive machine () is active and the power flow between the drive machine () and a drive output () is disconnected in a gearbox (), the active drive machine () from the drive output () by opening of one of a plurality of shift elements (A to F) that is held in a closed operating state in order to realize the operating state present before the demand for decoupling of the active drive machine (). The method also includes then actuating the plurality of shift elements (A to F) in a manner dependent on the present operating state profile of the vehicle drivetrain () and with the active drive machine () decoupled from the drive output ().

Method for operating a vehicle drive train

A method for operating a motor vehicle having a transmission (), the method including closing a first number of shift elements and opening a second number of shift elements in each selected, force locking gear ratio of the transmission (); closing one shift element less, and therefore opening one shift element more than in a selected, force locking gear ratio when a transmission () is not force locking in the sailing mode; adjusting the respectively closed and opened shift elements as a function of at least one operating condition of the motor vehicle in the sailing mode; and checking, at least on the basis of the rotational speed of the transmission input shaft (), whether a previously closed, positively locking shift element (A, F) to be opened is actually opened in the sailing mode during adjusting of the respectively closed and opened shift elements.

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Amtzell, Germany

Magnus Stiefenhofer