Zf Friedrichshafen Ag

Andreas Schmidt

Georg Mihatsch

Ruben Cueppers

Max Trautwein

Thilo Schmidt

Jorg Arnold

Valentine Herbeth

Klaus Steinhauser

Gabor Diosi

Anton Fritzer

Christoph Margraf

Markus Maurer

Martina Jehle

Jörg Arnold

Christian Pannek

Christian Villing

Mario Hasel

Johannes Brockmann

Jonas Knör

Christoph Köhler

Valentine Vincent

Daniel Zerlaut

Jakob Mayer

Michael Miller

Thorsten Schaetzle

Christian Hunger

Fabian Schöniger

Angelique Schwimmer

A vehicle transmission includes a hydraulic circuit and a control unit. The control unit is configured to: obtain () a target pressure specification; convert () the target pressure specification into a target volume flow rate; determine () a valve volume flow rate as a function of the target volume flow rate and as a function of parameters that represent system properties of the hydraulic circuit; determine () a pressure drop at a valve due to flow forces as a function of the valve volume flow rate; determine () a compensated valve output pressure as a function of the valve volume flow rate and the pressure drop; determine () the electric control current as a function of the compensated valve output pressure; and activate a valve with the electric control current.

Method for the open-loop control of an electrically controllable valve in a vehicle transmission

A method for operating a transmission () is provided, which includes a hydraulic pump drivable on a transmission-input end and at least one form-locking shift element (A, F). One of the shift-element halves is displaceable between a first end position and a second end position with a hydraulic pressure of the hydraulic pump. The current position of the shift-element half is detected with a sensor and is stored as a specified end-position value if the shift-element half is located in one of the end positions, the hydraulic pump is driven, and the shift-element half is actuated, with the hydraulic pressure, towards the current end position. When the hydraulic pressure is less than a threshold value, a deviation is determined between the current position of the shift-element half and the specified end-position value. The hydraulic pressure is increased when the deviation is greater than a threshold value.

Method and control unit for operating a transmission

A method for operating an automatic transmission includes shifting the automatic transmission to a substitute gear if, after adjusting a first one of at least one positive-locking shift element towards a closed configuration, the first one of the at least one positive-locking shift element occupies an intermediate position. The first one of the at least one positive-locking shift element does not participate in the transmission of power in the substitute gear. A related transmission control device for an automatic transmission is also provided.

Method and control device for operating an automatic transmission

A method for operating an automatic transmission is provided. The method includes initiating a synchronization of a positive shifting element of the automatic transmission. The method also includes closing a first non-positive shifting element of the automatic transmission and positioning a second non-positive shifting element of the automatic transmission at an engaged configuration of the second non-positive shifting element during the synchronization of the first positive shifting element in order to synchronize the first positive shifting element.

Method for operating an automatic transmission

A method for operating an automatic transmission is provided. The method includes initiating a synchronization of a positive shifting element of the automatic transmission while the automatic transmission is operating at less than a threshold output speed. The method also includes closing a first non-positive shifting element of the automatic transmission and positioning a second non-positive shifting element of the automatic transmission at an engaged configuration of the second non-positive shifting element during the synchronization of the first positive shifting element in order to synchronize the first positive shifting element.

A method of engaging a form-interlocking shifting element to obtain a gear in an automatic transmission in which at least one further, frictional shifting element is involved in obtaining the gear to be engaged and a shifting element, not involved in obtaining the gear to be engaged but which serves as a synchronizing shifting element, is actuated in order to synchronize the interlocking shifting element to be engaged. The further, frictional shifting element, involved in engaging the gear, is engaged and then disengaged, to a defined extent, to bring the frictional shifting element to a slipping condition, in order to ensure the engagement of the interlocking shifting element.

Procedure for engaging a form-locking shift element to realize a gear in an automatic transmission, whereat at least one further friction shift element is to be engaged to realize the gear to be activated

The present subject matter provides a method for operating an automatic transmission in a limp mode. The method includes actuating a first non-positive shifting element to an engaged configuration and actuating a second non-positive shifting element to the engaged configuration. A positive shifting element is substantially synchronized after actuating the second non-positive shifting element. The method also includes commanding the positive shifting element to actuate from a disengaged configuration to the engaged configuration.

Method for operating an automatic transmission in a limp mode

A method for operating an automatic transmission is provided. The method includes synchronizing a first positive shifting element of the at least one positive shifting element with a first process, a second process or a third process depending upon an input speed and/or an output speed of the automatic transmission. The first process, the second process and the third process can provide smooth and/or satisfactory shifting of the first positive shifting element at various input speeds and output speeds of the automatic transmission.

A method of operating a vehicle drive-train comprising an internal combustion engine and a transmission system functionally connected to the internal combustion engine. The transmission has an interlocking shifting element, one shifting element half of which is functionally connected to the transmission input shaft while the other shifting element half is functionally connected to a transmission output shaft. Upon receipt of a command to change the transmission from a neutral position, in which a force flow through the transmission is interrupted, to an operating condition, in which the force flow through the transmission is produced, the interlocking shifting element is changed to an engaged operating condition. A speed difference between the shifting element halves is brought by varying the speed of the internal combustion engine into a speed difference window within which the interlocking shifting element can be changed to its engaged operating condition.

Method for operating a vehicle drive train having an internal combustion engine

A method for terminating a gearshift for an automatic transmission for a motor vehicle is provided, wherein a positive-locking shifting element is involved. After the initiation of the gearshift, there is an evaluation of the continuous signals of at least one control unit of the vehicle, which affect the engine torque and thus the turbine speed gradient. Based on the evaluation of the signals, an upcoming change to the turbine speed gradient that exceeds a first predetermined threshold value or falls short of a second predetermined threshold value is detected, and, upon such detection, the gearshift is terminated.

Method for terminating a gearshift for an automatic transmission for a motor vehicle wherein at least one positive-locking shifting element is involved

A method of operating a transmission device () having a plurality of frictionally engaging shift elements (B, C, D and E) and at least one form-locking shift element (A, F) for implementing different transmission ratios. Upon a requested change in operating state of the transmission device (), the at least one form-locking shift element (A) is transferred into an at least nearly load-free state, during which the form-locking shift element (A) is transferred from an engaged to a disengaged operating state by increasing the transfer capability of at least one frictionally engaging shift element (E), which is not engaged in the power flow of the transmission device () either to represent the present operating state or to represent the requested operating state.

Method for operating a transmission device having a plurality of friction-fit shift elements and at least one form-fit shift element

A method of controlling the system pressure in an automatic transmission having interlocking shifting elements in which, during shifts and gear engagement and gear disengagement processes involving interlocking shifting elements, as a function of the engagement and disengagement times of the interlocking shifting elements involved and the shift conditions of the frictional shifting elements involved, the system pressure is increased to an elevated pressure that enables rapid engagement or disengagement of the interlocking shifting elements, in such manner that the system pressure is increased in at least two phases whose timing depends on the shift conditions of at least one of the shifting elements involved.

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Bavendorf, Germany

Andreas Schmidt