Zf Friedrichshafen Ag

Jochen Breuer

Mario Steinborn

Roland Mair

Melchor Moro-Oliveros

Thomas Jaeger

Christoph Ruechardt

Christian Mittelberger

Kai Bornträger

Thomas Jäger

Stefan Blattner

Thorsten Leim

Johannes Glückler

Josef Bader

Florian Schneider

Stefan Spühler

Martin Miller

Christoph Rüchardt

Thomas Hafen

Andreas Graf

Andreas Heinzler

Dennis Wohlfahrt

Benjamin Berger

Fabian Ley

Rick Hauschwitz

Stefan Bemetz

Hannes Werner

A method for operating a motor vehicle () having at least one driven axle () with a locking differential (), where when the motor vehicle () is driving and the locking differential () concerned is engaged on at least one driven axle (), it is checked whether the motor vehicle is driving round a curve. If it is found that the motor vehicle is driving round a curve, the engaged locking differential () is actuated to disengage it and it is checked whether the locking differential () concerned has in fact been disengaged. If it is found that the locking differential () concerned has not been disengaged, the wheel of the driven axle () concerned on the outside of the curve is braked.

Method and control device for operating a motor vehicle

A method for compensation of a support torque at a combustion engine and transmission which provide an overlay of combustion engine and electric machine. The combustion engine, the electric machine, and a transmission gearset are connected with each other via a planetary gearset, which is positioned in front of a downstream transmission gearset. The invention concerns a transmission gearset of a three-shaft transmission, each with a transmission input shaft for the electric machine, and for the combustion engine, and an output shaft. For the connection or disconnection of the transmission input shaft of the electric machine while driving, the electric machine is used for the synchronization of the input shaft of the electric machine, and the created support torque at the combustion engine is determined, based on this support torque, to match a combustion engine torque and thus to compensate the support torque.

Method for compensating a support torque on the combustion engine

A method of controlling an automated transmission with positioning cylinders () controlled by shift valves or venting valves (). At least one cut-off valve () is positioned in front of the shift or venting valves and a control device controls the valves while pressure pipes, which follow the cut-off valve (), are connected with one another following the cut-off valve (). Due to the fact that the cut-off valve (), for reasons of design simplicity and cost, is generally designed as a simple 2/2 way valve which only allows pressure increase but not pressure reduction, the method provides control of the shift valves or ventilation or venting valves (), of a non activated positioning cylinder (), so that the pressure pipe system is connected with an outflow pipe () for a pressure reduction in the pressure pipe system ().

Method for controlling an automated transmission

A method of controlling an automated transmission for motor vehicles with one or several pressure activated positioning cylinders (), via the assigned shift valves (), at least one main cut-off valve () which is positioned prior to the shift valves, and a control device for controlling the shift and main cut-off valves. The pressure requests, for the shifting, are determined and the respective main cut-off valves are triggered depending on the determined pressure requests. To enable a variable match of the supply pressure during transmission shifts, respective optimized pressures or pressure patterns are determined for certain shift scenarios which, for instance, consider a mass to be synchronized, the existence of a tooth-on-tooth position, or the like. Through this method, for instance, the load on shift elements, the shift timing, and the shift noise can be positively influenced.

A method of controlling a transmission brake of an automated change-speed transmission having a control cylinder, that is pressurized by inlet and outlet valves, and an upstream main cut-off valve by which a nominal pressure, supplied to the control cylinder, is regulated. Functional deviations of the transmission brake can be considered during a shifting operation, when the transmission is in neutral, the motor coupling clutch is disengaged and the transmission brake is engaged. The rotational speed gradient and the mass of the transmission components to be braked are determined and used to calculate the current braking torque of the transmission brake. The current braking torque relates to the current regulated nominal pressure, and the determined values are stored in a control unit and used during subsequent actuation of the transmission brake.

Method for controlling a gear brake for an automated change-speed gearbox

A method of controlling a shift of an automated group gearbox having a multi-step main transmission and a trailing two-step range group. An input shaft of the main transmission is driven by a drive device. The main transmission and a range group have synchronization devices with shift clutches. Each synchronization device, for the main transmission, has two shift positions for respective gear ratio steps and a neutral position and the range group synchronization device has only two shift positions to shift between two gear ratios steps. To accelerate range shifts, when synchronizing the range group, the main transmission input shaft is synchronized by controlling external synchronization aids to a target rotational speed at which either after the synchronization and shifting of the gear ratio step of the range group or independently from the current synchronization condition of the range group, the target gear ratio is engaged in the main transmission.

Method for shift control of an automated group gear

A method of operating a drivetrain of a motor vehicle. The drivetrain comprises a transmission arranged between a drive assembly and an axle drive, such that an input shaft of the transmission is connected, via a controllable separator clutch, to the drive assembly and an output shaft of the transmission is connected to the axle drive, and such that the transmission comprises at least one shifting element formed as a claw clutch. To reduce the probability that a tooth-on-tooth position may occur in a shifting element formed as a claw clutch, a torque is applied thereto by at least one transmission-internal assembly and/or at least one transmission-external assembly so that a speed difference at the claw clutch approaches a predetermined nominal value, and engagement of the claw clutch is only started when the speed difference of the claw clutch reaches the nominal value.

Method for operating a drive train

A method of operating a drivetrain of a vehicle comprising an engine, a clutch and a transmission comprising a claw-shifted main transmission and a synchronized upstream and/or downstream group, such that shifting from a current gear to a target gear is accomplished by actuating one of the synchronized upstream or downstream group and without actuating the engaged clutch and the claw-shifted main transmission. The method includes reducing engine torque and, when the engine torque is less than or equal to a limit value, the synchronized upstream or downstream group is actuated to disengage the currant gear. Then, when the engine torque is approximately zero, the synchronized downstream or upstream group is disengaged and held in neutral, and the speed of the engine is then adjusted to a target speed. The synchronized upstream or downstream group is actuated to engage the target gear and upon engagement the engine torque is increased.

Method for operating a drivetrain of a motor vehicle

A method of controlling an automated step-down transmission, arranged in a drivetrain between an engine and a drive axle, which includes a multi-stage main transmission and a range group. The main transmission has an intermediate transmission style with a countershaft having a transmission brake and an input shaft connected, via a clutch, to the engine. The main transmission shifts, without being synchronized, and the range group shifts, after synchronization, such that the engaged gear ratio of the main transmission remains engaged during a range shift operation. The range shift is accomplished by firstly reducing drive engine torque; secondly, disengaging the existing gear ratio of the range group; thirdly, remotely synchronizing the target gear ratio in the range group; fourthly, engaging the target gear ratio in the range group; and fifthly, increasing the drive engine torque.

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Tettnang, Germany

Jochen Breuer