Zf Friedrichshafen Ag

Marcus Gansohr

Christoph Rüchardt

Klaus Schweiger

Otto Ebner

Andreas Schwenger

Matthias Winkel

Thomas Knoblauch

Florian Schneider

Thomas Jäger

Rainer Petzold

Franz Bitzer

Peter Herter

Rupert Kramer

Johannes Kemler

Benjamin Berger

A method of determining at least one drag torque acting on the input side of an automatic transmission, such that prior to the determination a separator clutch located between the transmission and an engine is disengaged. To be able to carry out the determination regardless of the type of transmission concerned, also prior to the determination, the transmission is shifted to neutral and subsequently the drag torque is calculated when the engine is deactivated. For this, a first gradient of a transmission input rotational speed is determined, before an engine rotational speed of the engine falls below the transmission input rotational speed, and a second gradient of the transmission input rotational speed is determined, after the engine rotational speed falls below the transmission input rotational speed. The method is stored as a computer program stored on data carrier of a drive-train control unit of a motor vehicle.

Method for determination of at least a drag torque effective on the input side of an automatic motor vehicle transmission

A method of controlling a transmission brake of an automated change-speed transmission, of a countershaft design provided with claw clutches, the brake being functionally connected, on its input side, to a transmission shaft and actuated hydraulically or pneumatically by way of inlet and outlet valves such that, for an upshift from a gear under load to a target gear, when the loaded gear is disengaged, in order to synchronize the target gear, first the inlet valve is opened and the outlet valve is closed, then to produce a substantially constant braking torque, the inlet valve is closed after having been open for a determinable opening duration, and to reach a synchronous rotational speed, the outlet valve is opened after having been closed for a determinable closing duration. The time during which the inlet valve is open is determined as a function of a specified characteristic parameter of the synchronization process.

Method to control a transmission brake

A method of controlling a transmission brake that is actuated by inlet and outlet valves. For determining when to transmit a disengagement signal for opening the outlet valve, the current input and output speeds are determined and the respective gradients of these speeds are calculated. Variation of the input speed, during the disengagement of the brake, is determined as a function of the input gradient, the optimum time for reaching the synchronous speed, during brake disengagement, is determined from the input speed variation as a function of the output gradient, and the time interval until transmission of the disengagement signal is determined as a function of the current input and output speeds and their gradients, by a back-calculation from the time when the synchronous speed is reached, taking a disengagement dead time of the brake, between transmitting the disengagement signal and start of disengagement, into account.

Method for controlling a transmission brake

A method for controlling a drivetrain including an automatically shifted starting clutch and gear-shift clutch and a transmission, with a non self-locking clutch actuator, a gear actuator for engaging and disengaging transmission gears and a control unit which generates control commands for the clutch actuator and gear actuator and transmits such commands to the actuators such that, when the vehicle is at rest and a gear is engaged and if the clutch actuator fails, the clutch does not inadvertently engage. When a transmission gear is engaged, a control command is generated and sent for the clutch actuator to disengage the clutch. Thereafter, the vehicle speed is determined and if the speed is essentially zero and the clutch begins to engage, a control command is sent to the gear actuator to shift the transmission to its neutral position.

Method and device for controlling a motor vehicle drive train

A method of monitoring a hydraulic or pneumatic transmission control system, which comprises a pressure supply unit with a conduit directing a pressure medium under a supply pressure, and an actuating member for a clutch control element of a friction clutch. The actuating member has a pressure space which can be connected by a clutch control valve to the conduit, and in which the supply pressure is determined by a pressure sensor that can be connected to the conduit. The method includes the steps of determining the supply pressure by the pressure sensor, given that briefly opening the clutch control valve produces a pressure increase and/or a pressure gradient of the control pressure in the pressure space, and the currently existing supply pressure can be calculated from the control pressure, the pressure increase and/or the pressure gradient.

Procedure for controlling a hydraulic or pneumatic transmission control unit

A method for controlling an automotive hydraulic pump, wherein the hydraulic pump is activated to increase the pressure in a hydraulic accumulator associated therewith once the pressure falls below a predetermined lower pressure threshold, and the hydraulic pump is switched off once the pressure exceeds a predetermined upper pressure threshold value (P_O). The solution is to reduce fuel consumption of the vehicle, wherein the hydraulic pump is activated during different operating phases of the vehicle at different lower pressure values (P_U, P_U) in the event of a hydraulic pressure drop in the hydraulic accumulator of the hydraulic pump.

Method for controlling an automotive hydraulic pump

A method is proposed for determining a clutch application point in a transmission of a vehicle having a spring-actuated clutch system in which the clutch application point is adapted according to at least one adequate regulated quantity of the clutch system.

Method for determining the clutch application point

A known device for increasing the functional reliability for a hydraulic circuit of a hydraulic clutch having a pressure reservoir () and a release cylinder () which comprises a primary piston () and a secondary piston (). A compensation volume is developed in the sense that when the vehicle is at a standstill and the parking brake released, an unintentional release of the clutch is prevented. A pressure-monitoring/pressure-supply device () is used for determining a reference operating pressure and establishes a static pressure which, in case of any system error, only allows displacement of the secondary piston () such that the contact pressure of the clutch discs, against one another, is still sufficient to maintain the vehicle at a standstill.

Device for increasing the functional reliability of a hydraulic circuit of a hydraulically operable clutch

A method for clutch actuation at low temperatures for a motor vehicle having a hydraulically actuatable clutch, below a predetermined temperature a situation-dependent pre-opening of the clutch is executed when a braking is probable.

Method for actuating a clutch at low temperatures

A device for rendering a hydraulic actuating device operational. A motor vehicle clutch with an emitter-receiver system located in the transmission path of the actuating device comprising two pistons whose positions, relative to one another, can vary as a function of the desired operating behavior of the actuating device and is developed further such that in relation to the emitter-receiver system that is to be filled with fluid, operationality can be established comparatively quickly and by simple way. A fluid supply unit () comprises one impulse valve () that serves to release an essentially constant volume flow, acted upon by an impulse valve control device () which is constructed such that the fluid volume flow released by the fluid supply unit () and flowing into the emitter-receiver system () does not exceed a limiting volume flow Q.

Device for rendering operational a hydraulic actuating device

An operating time is determined by an approximation method within the scope of the method for determining the actual operating time of a hydraulic, electrohydraulic or electric component of a motor vehicle or of a working machine within a reference time or a monitoring period.

Growing community of inventors

Salem, Germany

Marcus Gansohr