Zf Friedrichshafen Ag

Wilfrid Eberhard

Gerhard Hermann Martin

Bernd Ummer

A method of operating a transmission device comprising at least one input shaft and at least two output shafts. Torque that is present at the input shaft can be distributed between the two output shafts with a variable degree of distribution which can be changed according to the operating state depending on a transmission capability of at least one shift element. When a request to set a predefined degree of distribution is received, a mechanical self-locking torque of the transmission device&#x2014;which influences the degree of distribution between the output shafts and is dependent upon the torque present at the input shaft&#x2014;is determined, and a difference between the mechanical self-locking torque and a target overall locking torque of the transmission device that is equivalent to the required degree of distribution is determined. The transmission capability of the at least one shift element is set depending on this difference.

Operation method of a transmission device

A method of the rapid filling of a hydraulically actuated multiple-disk shifting element () of a motor vehicle transmission (), in particular a disk clutch () of an all-wheel transfer transmission (). The disk shifting element () is filled using a target value (p_soll) for the filling pressure which depends on the motor speed (n_mot). In the event that the motor speed (n_mot) changes during a filling process, the target value (p_soll) for the filling pressure is adapted as a function of the new motor speed (n_mot).

Method for quickly filling a hydraulically actuated multiple disc shifting element of a motor vehicle transmission

A method of determining an applied actuation touch point pressure value of a frictionally engaged shift element of a transmission at which transmission, via the shift element, is approximately zero, and an increase in pressure relates to an increase of the power transmission via the shift element. The method includes supplying a predefined pressure to the shift element at which power transmission is zero. Increasing the target pressure by an offset pressure to transfer the shift element into a predefined operating state which initiates time monitoring. Determining a characteristic of the actual pressure. After a testing time, a monitoring period is compared with a reference period. When the monitoring period is less than or equal to the reference period, the applied pressure is set to be equivalent with the target pressure.

Determination method for actuation touch point pressure value of a friction shift element

A method of operating a vehicle drive train, whereby the drive train comprises a drive unit, a transmission, and an all-wheel splitter having an automatically operating clutch, positioned between the transmission and the output. The clutch is operated in a continuous slip mode and in such a way that the all-wheel splitter splits the transmission output torque for variable torque distribution to driven axles. The splitting of the output torque to the driven axles is performed by a control unit, implemented into the all-wheel drive strategy, so that the output torque, less a predetermined nominal torque, is transferred to a first axle, and the nominal torque is transferred to a second axle. When defined operating conditions are met, a limiting of the torque, set by the drive unit, and/or the nominal torque, set by the all-wheel strategy, occurs to avoid a thermal overloading of the clutch of the all-wheel splitter.

Drive line operation method

A method for operating a vehicle drive train comprising a drive unit, a transmission, and an all-wheel splitter having a clutch. The all-wheel splitter is positioned between the transmission and the output and splits a transmission output torque to vary the torque distribution to driven axles of the output. The split of the output torque to the driven axles is performed by a control unit in such a way that the transmission output torque, less a predetermined nominal torque set by the all-wheel drive strategy, is transferred to a first axle while the nominal torque is transferred to a second axle. When defined operating conditions are met, a clutch monitoring function is activated and the nominal torque is replaced by a torque definition of the clutch monitoring function so that the torque which is transferred by clutch to the second driven axle, is increased, then kept constant, and thereafter reduced.

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Tettnang, Germany

Wilfrid Eberhard