Zf Friedrichshafen Ag

Tobias Rolser

Thilo Schmidt

Markus Herrmann

Christian Popp

Georg Gierer

Armin Gierling

A device for operating a parking lock () of a transmission () includes an engagement spring () for engaging the parking lock (), a hydraulic actuator () for disengaging the parking lock (), an electrohydraulic control unit () for hydraulically actuating the actuator (), and an electronic control unit () for electrically actuating the actuator () and the electrohydraulic control unit (). The actuator () includes a hydraulic piston () operatively connected to the parking lock (), is actuatable by system pressure (P_sys) of the electrohydraulic control unit () via a pressure line () upon disengagement of the parking lock (), and is mechanically interlockable by an interlocking device (). A choke unit () includes an orifice () and a non-return valve () and is installed in the pressure line () downstream from the hydraulic piston ().

Device for operating a parking lock of a motor vehicle transmission

An electrohydraulic transmission control system () includes a parking lock valve (). The electrohydraulic transmission control system () is configured such that, during normal operation of the electrohydraulic transmission control system () in which at least one electrohydraulic pressure adjuster (EDSSYS) is actuatable with current, the parking lock valve () can be held in a defined operating state in which an actuation pressure (p_sys) acts on a parking lock cylinder () above a normal pressure level. The electrohydraulic transmission control system () is configured such that, during emergency operation of the electrohydraulic transmission control system () in which the at least one electrohydraulic pressure adjuster (EDSSYS) is not fed with current and the actuation pressure (p_sys) is at least temporarily set to an emergency pressure level higher than the normal pressure level by the at least one pressure source (), a pressure level of the actuation pressure (p_sys) that holds the parking lock valve () in the defined operating state corresponds at least approximately to the emergency pressure level.

Hydraulic valve system of a parking lock device

An electrohydraulic transmission control system having a parking lock valve by which a parking lock cylinder of a parking lock device can be charged with an actuation pressure adjustable in an operating-state-dependent manner by at least one pilot pressure adjustable in the region of an electrohydraulic pressure adjuster and/or one pressure source. Above a defined actuation pressure level, the parking lock valve is held in a defined operating state in which the actuation pressure can be applied to the parking lock cylinder. The actuation and pilot pressures can be applied to a valve device such that when the actuation and pilot pressure levels approximately correspond to one another, the region of the control system which conducts the actuation pressure is operatively connected, upstream of the parking lock valve, to a pressure region in the region of the valve device with a pressure lower than the defined actuation pressure level.

Hydraulic valve system for actuating a parking lock device

Description of a hydraulic control system (A) for a hydrodynamic torque converter () with a controlled torque converter lockup clutch () of an automatic transmission for controlling a supply pressure (p_WD_zu) of the torque converter () and a supply pressure (p_WK_zu) of the torque converter lockup clutch (). The torque converter lockup clutch () is engaged when the supply pressure (p_WD_zu) of the torque converter () is lower than a predefined pressure level of the supply pressure (p_WK_zu) of the torque converter lockup clutch. A converter pressure valve (WDV) is provided for controlling the supply pressure (p_WD_zu) of the torque converter (), and a converter coupling valve (WKV) for controlling the supply pressure (p_WK_zu) of the torque converter lockup clutch, where their valve slides (WDV_S, WKV_S) can be acted upon by at least one pre-control pressure (p_VS) and one system pressure (p_sys). When the torque converter lockup clutch () is disengaged, the valve slide (WKV_S) of the converter coupling valve (WKV) is acted upon in such a way on an active surface () by the reverse pressure (p_WD_ab) of the torque converter (), and when the torque converter lockup clutch () is engaged, is acted upon in such a way on the active surface () by the reverse pressure (p_WK_zu) of the torque converter lockup clutch (), that at least either the supply pressure (p_WD_zu) of the torque converter () or the supply pressure (p_WK_zu) of the torque converter lockup clutch () is higher than a predefined pressure level (p) over the entire operational area of the torque converter ().

Growing community of inventors

Berg, Germany

Tobias Rolser