Zf Friedrichshafen Ag

Andreas Feiner

Alexander Hoffmann

Rainer Novak

Markus Terwart

Tobias Pfleger

Andreas Roedler

Thomas John

A method for operating a parking lock device () with a hydraulic system (), the method including, when there is a demand to engage the parking lock device () originating from a disengaged operating condition of the parking lock device (), applying a pilot pressure (p_EDS) at the parking lock valve (PSV) and applying the main pressure (p_sys) at the parking lock valve (PSV), if necessary, via the positioning valve (POSV). The pilot pressure (p_EDS) and the main pressure (p_sys) are each guided to defined pressure levels at which the parking lock valve (PSV) is transferrable into the further operating condition range of the parking lock valve (PSV) by the active actuating force against the pilot pressure (p_EDS) and against the pressure between the parking lock valve (PSV) and the parking lock cylinder ().

Method for operating a parking lock device by means of a hydraulic system

A method for operating a parking lock device with a hydraulic system, the method including applying the pressure between the parking lock valve and the pressure chamber at the parking lock valve against the actuating force. Moreover, when there is a demand to disengage the parking lock device, the method includes applying the pilot pressure at the parking lock valve against the actuating force when the pressure between the parking lock valve and the pressure chamber of the parking lock valve is less than a threshold value at which the parking lock valve is transferred into a further operating condition range. Additionally, when there is a demand to disengage the parking lock device, the method includes adjusting the pilot pressure applied at the positioning valve to a pressure level at which the positioning valve is transferred into or held in its defined operating condition range.

A method for disengaging a parking lock of a dual-clutch transmission of a motor vehicle with at least one drive unit is provided. The method includes, upon detection of an absolute value of a road inclination along a longitudinal axis of the motor vehicle exceeding a predetermined threshold and upon actuation of a selector lever for disengaging the parking lock prior to disengagement of the parking lock, issuing a torque request to the drive unit and closing a power-shifting clutch of the dual-clutch transmission with an engaged gear in a sub-transmission to which the power-shifting clutch is allocated. A torque transferred by the power-shifting clutch as a consequence of closing the power-shifting clutch and the torque request to the drive unit is a relief torque. The torque request to the drive unit and the closed power-shifting clutch are selected to counteract a torque, supported by a parking lock pawl, applying with an engaged parking lock by drive wheels on an output side at the transmission.

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Isny, Germany

Andreas Feiner