Zf Friedrichshafen Ag

Sven Bieber

Marcus Hiemer

Stephan Schinacher

Jan-Frederik Kuhn

Thomas Kurz

Andreas Schwarz

Jürgen Legner

Mario Brugger

Markus Lukassek

Matthias Madlener

Stefan Traub

Simon Geiger

Robert Morrison

Timo Maise

Anton Arnold

Tobias Dieterich

The present invention relates to a method for heating a transmission () for a working machine having a plurality of hydraulically actuated shifting elements (). The method involves the sending (III) of a closing signal for closing shifting elements () in order to block the transmission (). In addition, the method entails pulsed actuation (V) for opening and closing of at least one of the closed shifting elements () while the transmission () remains blocked. Furthermore, the present invention relates to a control unit which is designed to carry out such a method, and to a transmission for a working machine with such a control unit.

Method for heating a gearbox for a working machine

A method for calibrating an actuation of a converter lock-up clutch of a hydrodynamic torque converter having a pump wheel and a turbine wheel connected to a power-split transmission. The transmission has at least two clutches each connected to a respective power-split shaft assembly and each configured be actuated separately to close and open in order to apply a clutch torque to the turbine wheel so that a rotation speed difference between the pump wheel and the turbine wheel changes. The method includes opening the converter lock-up clutch and the at least two clutches each connected to a respective power-split shaft assembly of the transmission, rotating the pump wheel with a specified rotation speed, and applying a clutch torque to the turbine wheel as a function of an actual rotation speed difference. Clutches connected to a different respective power-split shaft assembly of the transmission are actuated in the closing direction.

Control method for calibrating an actuation of a converter lock-up clutch of a hydrodynamic torque converter

A method for holding a vehicle on a gradient. The vehicle has a transmission with an output, a first clutch and a second clutch. The primary sides of the first and second clutches are mechanically operatively connected to one another. The secondary sides of the first and second clutches are mechanically operatively connected to one another and to the output of the transmission. Different transmission ratios can be engaged by way of the first clutch and the second clutch, and the first clutch is in an engaged state. The method includes the additional closure of the second clutch in order to block the transmission and thus hold the vehicle at a standstill on a gradient.

Method for holding a vehicle on a gradient

A process for determining a setpoint rotational speed of a work machine engine, having a continuously variable transmission, based on operation of power hydraulics. The setpoint rotational speed for highly productive operation is determined, without knowledge current operation of the power hydraulics, by a basic engine speed setting. With knowledge of the current operating state, the setpoint rotational speed is determined by the basic speed settings and low or high engine speed settings. The low speed setting alone determines setpoint rotational speeds that are lower than the basic speed setting or a combination of the low and basic speed settings. The high speed setting alone determines setpoint rotational speeds that are higher than the basic speed setting or a combination of the basic and high speed settings. The speed settings can comprise a setpoint rotational speed range of above a reciprocal transmission range of the variable transmission.

Method for ascertaining the target rotational speed of a drive machine of a work machine comprising a continuously variable transmission and a working hydraulic system

A method of shifting a transmission in which a clutch, located in the torque flow, in a first gear and in a second gear is controlled in such manner that, in the first gear, the clutch slips and transmits a first torque and, in the second gear, the clutch slips and transmits a second torque. The second torque is chosen such that an output torque of the transmission remains the same when shifting from the first gear to the second gear.

Smooth gear change during inching

A method for controlling the transmission of a working machine, by which, with at least one sensor of the working machine, at least one specific parameter is determined and transmitted to a control unit for controlling the transmission. The working machine has a lifting mechanism and the at least one specific parameter which characterizes an actuation condition of the lifting mechanism. A predetermined shifting strategy is adapted, by the method, as a function of the at least one specific parameter.

Method and device for controlling a transmission of a working machine

A method for the operation of a vehicle drive-train of a working machine having a drive motor, a transmission whose transmission ratio can be varied continuously, and a drive output. A rotational speed (nmot) of the drive motor can be varied by the driver, by the driver's actuation of a first control element (), within a rotational speed range () delimited by an upper characteristic line (nmoto) and a lower characteristic line (nmotu). The characteristic lines (nmoto, nmotu) are functions of a reciprocal transmission ratio (irez) of the transmission. Furthermore, the rotational speed (nmot) of the drive motor that can be set by the driver by way of the first control element (), can be influenced by the driver's actuation of a second control element () and as a function of an operating condition of the working machine.

Operating method for a vehicle drive train of a working machine including a drive motor, a transmission and an output

A power-split transmission device for a vehicle, which connects a drive engine to a drive output, having a hydrostatic unit for continuous adjustment of the transmission ratio at a transmission unit, and two range clutches that alternately operate for respectively associated driving ranges with different transmission ratios. A control unit, during regular vehicle deceleration, implements the driving range change from a first range, with higher transmission ratios, to a second range, with lower transmission ratios, by switching from the first to the second range clutch in accordance with a synchronous point dependent deceleration control logic. In the special case of an unexpected increase of the deceleration dynamic at the beginning of an already initiated driving range change from the first to the second driving range, the control unit immediately forces the change by bypassing the synchronous point dependent deceleration control logic when other boundary conditions are fulfilled.

Transmission device and method for operating the same

A method for operating a vehicle drive-train having a continuously power-branched transmission with secondary coupling. In the open operating condition of reversing clutches of a reversing gear unit, torque applied in the area of a drive output can be supported by a range group in the area of a variator. In the event of a command to interrupt the power flow between a drive engine and the drive output, it is checked whether the vehicle is on an inclined surface and if the result of that inquiry is positive, the power flow between the drive engine and the transmission is interrupted at the latest when the rotational speed of the drive output is reduced to zero by opening the reversing clutches, while the active connection between the drive output and the variator is maintained by way of the range group.

Method of operating a power path with continuously power-split transmission and with secondarily coupled power split

A method is described for determining a reference value of an actuating current that corresponds to a defined operating point of an electro-hydraulically actuated frictional shifting element of a continuously variable power-branched transmission, at which the shifting element transmission capacity is zero, and starting from which an increase of actuating force immediately increases the transmission capacity. The actuating current reference value of the shifting element, when closed with a further shifting element decoupled from the transmission output and when a transmission input rotational speed is higher than a defined threshold, is reduced until a rotational speed difference between the rotational speeds of the shifting element halves exceeds a predefined limit value such that, at the time when the limit value is exceeded, the reference value of the actuating current is the reference value of the actuating current that corresponds to the defined operating point of the shifting element.

Method for determining a reference value of an actuating current

A device for varying the swept volumes of first and second hydraulic machines, whose swept volumes depends upon pivoting positions of adjustable axes thereof which can be connected to one another by first and second lines. The axes can be coupled to a piston-cylinder device which is adjustable by a control valve unit for pivoting the axes. Pressures in the area of the hydraulic machines can be limited by the control valve unit. The control valve unit can be coupled to a respective first or second line with the highest pressure. A device for determining an existing actual pressure is located upstream of the control valve unit, at least in the area of one of the first and the second lines that connects with the first and the second hydraulic machines. The control valve unit can be actuated based on the actual pressure value determined by the device.

Device for varying the volumes of a first hydraulic machine and a second hydraulic machine

A method for determining a draining behavior of a hydraulically actuated transmission shifting element. By applying actuating pressure, the shifting element is changed from a completely drained, open operating condition to a completely filled closed operating condition, and the reference filling time, until the closed condition has been reached, is determined. Upon recognition of the closed condition, then by adjusting the actuating pressure for a predefined draining time, the shifting element is changed to its open condition and, thereafter, again completely filled and closed. Upon recognition of the closed condition, the shifting element is actuated direction toward the open condition by reducing the actuating pressure. Then, before completely opening, the shifting element is again returned to its closed operating condition and the filling time, until the partially drained shifting element has reached the completely filled and closed operating condition, is determined.

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Bermatingen, Germany

Sven Bieber