Zf Friedrichshafen Ag

Ulf Lang

Jürgen Blaser

Markus Eisele

Jörg Arnold

Friedrich Reiter

Jens Weller

Olaf Langwald

Paul Myszka

Ralf Baus

Fabian Lebherz

Matthias Wild

Frank Schuhmacher

A transmission between a drive aggregate and a drive output of a vehicle drivetrain has a hydrodynamic starting element and a powershiftable main transmission with a plurality of forward gears, at least one reversing gear, a transmission input, a transmission output, and frictional shifting elements. In each gear a first number of shifting elements are closed and a second number of shifting elements are open. A downstream range group has at least one interlocking shifting element which can be shifted between a first and second driving ranges. With the drive aggregate running, the vehicle at a standstill or nearly so, the main transmission in neutral, and a shift request received to change the downstream range group, shifting elements of the main transmission are actuated, thereby bracing the transmission input against a transmission housing and decoupling the transmission input from the transmission output. The downstream range group is then shifted.

Method and control apparatus for operating a transmission of a motor vehicle

A transmission is between a drive aggregate and a drive output of a vehicle drivetrain and includes a hydrodynamic starting element and a powershiftable main transmission having a plurality of forward gears and at least one reversing gear. The main transmission has frictional shifting elements, where in each gear a first number of shifting elements are closed and a second number of shifting elements are open. A downstream range group is connected downstream from the main transmission and has at least one interlocking shifting element that can be shifted between first a second driving ranges. With the drive aggregate running, the motor vehicle at a standstill or nearly so, and the main transmission in neutral, a shift request to change the downstream range group is received. The shifting elements of a reversing gear are at least partially closed, and the driving range of the downstream range group is then changed.

A method is disclosed for controlling gearshifts in a transmission of a motor vehicle. Devising a shifting strategy of the gearshift takes into account the operation of a sustained-action braking device (). To organize gearshifts in an optimum way having regard to the operation of the sustained-action braking device (), at the beginning of the operation of the sustained-action braking device () it is examined with what starting criterion the operation of the sustained-action braking device () was initiated. Depending on the starting criterion identified, a current workload of the sustained-action braking device () is compared against an associated threshold value. Alternately, a gearshift is carried out directly to a lowest possible gear of the motor vehicle transmission (). If the comparison of the current workload of the sustained-action braking device () exceeds the threshold value, then the shifting strategy is adapted.

Method for controlling gear changes in a transmission of a motor vehicle drivetrain

A method of operating a motor vehicle. A request for coupling a power take-off is detected. It is checked () whether relevant boundary conditions for coupling the power take-off are fulfilled. If the boundary conditions are fulfilled, a system pressure for actuating the power take-off clutch is built up (). It is checked () whether sufficient system pressure to actuate the power take-off clutch has been built up. When sufficient system pressure has sufficiently been built up, a confirmation signal is produced (). In reaction to the confirmation signal, a driving transmission control unit is modified () in order to actuate the at least one shifting element of the driving transmission with a higher actuation pressure than with an unmodified driving transmission control unit.

Method for operating a motor vehicle comprising a power take-off unit

A monitoring device and a method for operating an idling automatic transmission of a motor vehicle having a torque converter which includes at least one pump wheel and a turbine wheel that are designed to transmit torque hydrodynamically from one to the other. The method includes at least the following steps of: determining a rotational speed of the turbine wheel; determining a load on the motor of the motor vehicle; and recognizing whether there is a blockage in the drive-train of the motor vehicle or whether the torque converter is running dry, as a function of the turbine rotational speed and the motor load detected.

Fault detection for a torque converter

A method for operating a motor vehicle drivetrain having a transmission connected between a drive aggregate and a drive output, a Power Take-Off (PTO) that can be coupled to the drive aggregate on drive aggregate side to take up drive torque from the drive aggregate. In order to determine the torque taken up by the PTO, the transmission is first shifted to interrupt torque to the transmission output. Thereafter, a defined torque is delivered by the drive aggregate, at least with the PTO coupled to the drive aggregate, and, during this at defined time-points, rotational speeds of a shaft driven by the drive aggregate are determined and from this an angular acceleration of the shaft is determined. A first torque of the shaft is determined from the shaft angular acceleration while the PTO is coupled. Based on the first torque, the torque taken up by the PTO is determined.

Method and control unit for operating a drivetrain of a motor vehicle comprising a power take-off

A method for operating a drive-train of a motor vehicle. The drive-train having a transmission connected between a drive aggregate and a drive output. A hydrodynamic starting element is connected between the drive aggregate and transmission. The starting element includes a converter and converter lock-up clutch. A Power Take-Off (PTO) can be coupled to the drive aggregate on the drive aggregate side to take up drive torque delivered by the drive aggregate. In order to determine the torque taken up by the PTO, the lock-up clutch is operated in a rotational-speed-regulated manner at least when the PTO is coupled to the drive aggregate in order to set a defined target slip at the lock-up clutch. As a function of the actuation pressure of the lock-up clutch required for setting the target slip when the PTO is coupled, the torque taken up by the PTO is determined.

A drain valve for draining liquid out of a container which comprises an essentially cylindrical opening that passes through a thickened area of the container wall, with an internally threaded section formed at an outer end thereof, followed by an interior space with a larger diameter into which a duct opens, and opposite the interior space an inner section with a smaller diameter opens into the container. A step is provided between the interior space and the inner section and serves as the seat for an associated end face of the valve element. A step between the interior space and the bore, on the one hand, and the inner end face of the valve element, on the other hand, are designed to co-operate as a valve seat which progressively opens and closes as the valve element is displaced.

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Friedrichshafen, Germany

Ulf Lang