Zf Friedrichshafen Ag

Andreas Schwarz

Thomas Kurz

Sven Bieber

Hans Höfler

Manfred Sieger

J&ouml;rg Geis

Karl K&uuml;hner

A method for calibrating an actuation of a converter lock-up clutch of a hydrodynamic torque converter having a pump wheel and a turbine wheel connected to a power-split transmission. The transmission has at least two clutches each connected to a respective power-split shaft assembly and each configured be actuated separately to close and open in order to apply a clutch torque to the turbine wheel so that a rotation speed difference between the pump wheel and the turbine wheel changes. The method includes opening the converter lock-up clutch and the at least two clutches each connected to a respective power-split shaft assembly of the transmission, rotating the pump wheel with a specified rotation speed, and applying a clutch torque to the turbine wheel as a function of an actual rotation speed difference. Clutches connected to a different respective power-split shaft assembly of the transmission are actuated in the closing direction.

Control method for calibrating an actuation of a converter lock-up clutch of a hydrodynamic torque converter

A method for holding a vehicle on a gradient. The vehicle has a transmission with an output, a first clutch and a second clutch. The primary sides of the first and second clutches are mechanically operatively connected to one another. The secondary sides of the first and second clutches are mechanically operatively connected to one another and to the output of the transmission. Different transmission ratios can be engaged by way of the first clutch and the second clutch, and the first clutch is in an engaged state. The method includes the additional closure of the second clutch in order to block the transmission and thus hold the vehicle at a standstill on a gradient.

Method for holding a vehicle on a gradient

A method of shifting a transmission in which a clutch, located in the torque flow, in a first gear and in a second gear is controlled in such manner that, in the first gear, the clutch slips and transmits a first torque and, in the second gear, the clutch slips and transmits a second torque. The second torque is chosen such that an output torque of the transmission remains the same when shifting from the first gear to the second gear.

Smooth gear change during inching

A control unit () that outputs a shift signal to a transmission () when the control unit recognizes that the bucket () is in a loading position, such that the transmission () shifts not to the next-higher gear ratio, but to a further, even higher, gear ratio.

Method for operating a transmission

A method for controlling the transmission of a working machine, by which, with at least one sensor of the working machine, at least one specific parameter is determined and transmitted to a control unit for controlling the transmission. The working machine has a lifting mechanism and the at least one specific parameter which characterizes an actuation condition of the lifting mechanism. A predetermined shifting strategy is adapted, by the method, as a function of the at least one specific parameter.

Method and device for controlling a transmission of a working machine

A rotational speed-regulated internal combustion engine in a working machine, for example a wheel loader, shortly before the engaging a bridging clutch of a hydrodynamic torque converter, is switched over in such manner that the internal combustion engine operates under torque regulation when the bridging clutch of the hydrodynamic torque converter is engaged.

Method for operating a drive train

The invention is based on a process for determination of a coefficient of friction (&mgr;) of a hydraulically activated coupling ( ) or brake ( ) in a load-shifting transmission ( ). It is proposed that a drive shaft ( ) of the transmission ( ) be driven with a specified torque (T), that an output shaft ( ) of the transmission ( ) is blocked with a closed coupling ( ) or brake ( ) during a calibration run, the activation pressure (p) of coupling ( ) or brake ( ) is reduced in accordance with a specified course over time, the differential rotational speed (&Dgr;n) between the input ( ) and the output ( ) of the coupling ( ) or brake ( ) is recorded, the activation pressure (p) is ascertained in which the differential rotation speed (&Dgr;n) is greater than zero and a separation coefficient of friction (&mgr; ) is computed on the basis of torque (T), activation pressure (p) and a construction-conditioned coupling constant. By ascertaining the coefficient of friction &mgr;, the shifting can be conducted over the lifetime of the transmission ( ) with a constant shift quality.

Growing community of inventors

Langenargen, Germany

Andreas Schwarz