Zf Friedrichshafen Ag

Jens Weller

Jörg Arnold

Klaus Steinhauser

Georg Mihatsch

Ulf Lang

Jürgen Blaser

Christoph Hess

Fabian Lebherz

Matthias Wild

Paul Myszka

A transmission between a drive aggregate and a drive output of a vehicle drivetrain has a hydrodynamic starting element and a powershiftable main transmission with a plurality of forward gears, at least one reversing gear, a transmission input, a transmission output, and frictional shifting elements. In each gear a first number of shifting elements are closed and a second number of shifting elements are open. A downstream range group has at least one interlocking shifting element which can be shifted between a first and second driving ranges. With the drive aggregate running, the vehicle at a standstill or nearly so, the main transmission in neutral, and a shift request received to change the downstream range group, shifting elements of the main transmission are actuated, thereby bracing the transmission input against a transmission housing and decoupling the transmission input from the transmission output. The downstream range group is then shifted.

Method and control apparatus for operating a transmission of a motor vehicle

The invention relates to the actuation of a converter lock-up clutch () of a hydrodynamic torque converter () in a vehicle drive-train by means of a safety function where, in addition to a driving strategy function, the safety function can actuate the converter lock-up clutch () by issuing a clutch actuation command. For this purpose, at least one rotation speed at the torque converter () is monitored. If the monitored rotation speed is below a rotation speed threshold, the safety function commands an actuation of the converter lock-up clutch () in its opening direction.

Actuation of a converter lock-up clutch of a hydrodynamic torque converter by means of a safety function

A method for detecting a malfunctioning shift element in an automatic transmission is provided. The method includes operating the automatic transmission in an intermediate gear. A selected shift element of the automatic transmission is commanded to a disengaged configuration in the intermediate gear. The method also includes measuring a gear ratio of the automatic transmission while the automatic transmission is operating in the intermediate gear, and determining whether the selected shift element of the automatic transmission is malfunctioning based at least in part on the gear ratio of the automatic transmission in the intermediate gear.

Method for detecting a nonoperational shift element in an automatic transmission

A control unit of a motor vehicle for activating a form-locking shift element of a transmission of the motor vehicle in such a way that a defined rotational speed difference is defined, between an input-side component of the form-locking shift element and an output-side component of the form-locking shift element, in order to engage the form-locking shift element. The control unit monitors the rotational speed gradient of the rotational speed of the output-side component of the form-locking shift element from an activation time of the form-locking shift element, at which the engagement process of the form-locking shift element begins. The control unit generates a control signal for a drive assembly in order to increase the torque, at a drive assembly, in the event that the control unit determines that the monitored rotational speed gradient falls below a lower limit.

Growing community of inventors

Constance, Germany

Jens Weller