Zf Friedrichshafen Ag

Detlef Plath

Franz-Josef Schuler

Peter Spoerl

Friedemann Jauch

Uwe Firzlaff

Manfred Sulzmann

Klaus Müller

A method for operating a transmission of a vehicle drivetrain. A transmission ratio can be automatically changed during an operating state depending on a comparison of current operating state parameters with operating parameters stored in a control unit, and can be manually changed depending on a driver's request. Accordingly when the driver requests a change of the transmission ratio, the transmission ratio changes, and a timer starts. If the driver continues the ratio change from an actual transmission ratio value toward a larger or smaller transmission ratio value, the current operating parameters are compared with the stored operating parameters. Upon this comparison, the transmission shifts to higher ratios in comparison to the operating parameters stored in a control device at higher vehicle speeds, and/or a delay between sequential, cyclical transmission ratio changes varies depending on a vehicle deceleration and/or braking pressure in the region of a vehicle brake.

Method for operating a transmission unit of a vehicle driveline with an engine

A method of operating a transmission having a plurality of gears which can operate in an automatic shifting mode, during which a gear is selected automatically depending on the current driving situation, and also in a manual shifting mode during which a gear is selected depending on a driver's command. When the driver commands a shift, a change takes place from the automatic shifting mode to the manual shifting mode. A specific threshold value of the transmission output speed or an equivalent rotational speed value is associated with each gear and, when the driver commands a downshift, a target gear is determined as a function of the current transmission output speed or the equivalent rotational speed value. The gear selected as the target gear is the gear whose specific threshold value is higher than or equal to the current transmission output speed or the equivalent rotational speed value.

Transmission control method

A continuously variable transmission having an input cone pulley pair and an output cone pulley pair linked by and an encircling mechanism. One pulley of each pair is axially fixed and one pulley is axially displaceable to control the transmission ratio of the transmission. A recoil spring engages between the input moveable pulley and an axially fixed contact surface only when the transmission is in the low transmission ratio range for exerting a force to displace the input moveable cone pulley to a high transmission ratio to avoid damage to the transmission or starting clutch during towing.

Continuously variable transmission

A hydraulic fluid feed mechanism that feeds into a shaft () of a transmission having a hydraulic control device, by which the hydraulic feed mechanism can be supplied with hydraulic fluid, comprising a transmission housing () in which the shaft is held, and a housing cover () that is equipped with feed bores (), by which the hydraulic fluid is fed from the hydraulic control device into the shaft (). A hydraulic fluid line () is positioned between the hydraulic or pneumatic control device and a feed bore () in the housing cover () that extends parallel to the shaft (), with this hydraulic fluid line being comprised of a fitting () and a tube () which is permanently inserted into the fitting at nearly right angles, forming a pressure-tight seal. The fitting () is pushed through a transmission housing bore () that extends parallel to the shaft (), is separably inserted into the feed bore () forming a pressure-tight seal, and is axially mounted to the transmission housing () by a sealing ring ().

Growing community of inventors

Tettnang, Germany

Detlef Plath