Zf Friedrichshafen Ag

Alexander Hoffmann

Rainer Novak

Markus Terwart

Tobias Pfleger

Andreas Feiner

Martin-Joachim Bader

Karl Locher

Andreas Roedler

Thomas John

Frank Riever

A method for actuating a hydraulic system of a transmission comprising a variable displacement hydraulic pump and a pilot-controllable system pressure valve, the method including, in order to determine a pump characteristic curve of the hydraulic pump, initially transferring the hydraulic system into a defined operating condition range in which the volumetric output flow, routed via the system pressure valve and applied at the system pressure valve by the hydraulic pump, is greater or less than a hydraulic fluid flow out of the hydraulic system. The method further includes pilot-controlling the system pressure valve to set a defined pressure level of the system pressure. The method additionally includes reducing or increasing the volumetric output flow while monitoring the system pressure, and determining a volumetric output flow corresponding to the hydraulic fluid flow of the hydraulic system with a certain deviation of a current system pressure from the defined system pressure.

Method for actuating a hydraulic system of a transmission having a variable displacement hydraulic pump

A method for operating a parking lock device () with a hydraulic system (), the method including, when there is a demand to engage the parking lock device () originating from a disengaged operating condition of the parking lock device (), applying a pilot pressure (p_EDS) at the parking lock valve (PSV) and applying the main pressure (p_sys) at the parking lock valve (PSV), if necessary, via the positioning valve (POSV). The pilot pressure (p_EDS) and the main pressure (p_sys) are each guided to defined pressure levels at which the parking lock valve (PSV) is transferrable into the further operating condition range of the parking lock valve (PSV) by the active actuating force against the pilot pressure (p_EDS) and against the pressure between the parking lock valve (PSV) and the parking lock cylinder ().

Method for operating a parking lock device by means of a hydraulic system

A hydraulic system of a transmission includes a plurality of pressure control valves. A pilot force component and an actuating force component of additional pressure control valves are applicable in the direction of a first end position of a valve slide. A downstream pressure of the additional pressure control valves is applicable in the direction of a second end position of the valve slide. Clutch valves are configured to be brought into operative connection by a pilot-controlled valve unit with an area guiding pressure of a primary pressure circuit or with an additional valve unit. The additional valve unit is a pressure-limiting valve with a predefined pressure level adjusted upstream of the additional valve unit and connected downstream to a low-pressure area.

Hydraulic system of a transmission with a multiple number of pressure control valves

A method for operating a parking lock device with a hydraulic system, the method including applying the pressure between the parking lock valve and the pressure chamber at the parking lock valve against the actuating force. Moreover, when there is a demand to disengage the parking lock device, the method includes applying the pilot pressure at the parking lock valve against the actuating force when the pressure between the parking lock valve and the pressure chamber of the parking lock valve is less than a threshold value at which the parking lock valve is transferred into a further operating condition range. Additionally, when there is a demand to disengage the parking lock device, the method includes adjusting the pilot pressure applied at the positioning valve to a pressure level at which the positioning valve is transferred into or held in its defined operating condition range.

A method for disengaging a parking lock of a dual-clutch transmission of a motor vehicle with at least one drive unit is provided. The method includes, upon detection of an absolute value of a road inclination along a longitudinal axis of the motor vehicle exceeding a predetermined threshold and upon actuation of a selector lever for disengaging the parking lock prior to disengagement of the parking lock, issuing a torque request to the drive unit and closing a power-shifting clutch of the dual-clutch transmission with an engaged gear in a sub-transmission to which the power-shifting clutch is allocated. A torque transferred by the power-shifting clutch as a consequence of closing the power-shifting clutch and the torque request to the drive unit is a relief torque. The torque request to the drive unit and the closed power-shifting clutch are selected to counteract a torque, supported by a parking lock pawl, applying with an engaged parking lock by drive wheels on an output side at the transmission.

Dual-clutch transmission parking brake disengaging method of a vehicle

A method for controlling a hydraulic fluid supply system of an automatic transmission of a motor vehicle includes supplying the hydraulic fluid supply system with hydraulic fluid from at least one of a hydraulic pump controlled on an engine side and a hydraulic pump controlled on a gear set side. The method also includes controlling a cooling valve of the hydraulic fluid supply system as a function of detected motor vehicle parameters in order to set an adjusted power distribution with the hydraulic pump controlled on the engine side and the hydraulic pump controlled on the gear set side.

Method for controlling a hydraulic-medium supply system of an automatic transmission

A method for controlling a hydraulic fluid supply system of an automatic transmission of a motor vehicle includes supplying the hydraulic fluid supply system with hydraulic fluid from at least one of a hydraulic pump controlled on an engine side and a hydraulic pump controlled on a gear set side. The method also includes controlling a retaining valve of the hydraulic fluid supply system as a function of detected motor vehicle parameters in order to set an adjusted power distribution with the hydraulic pump controlled on the engine side and the hydraulic pump controlled on the gear set side.

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Lebach, Germany

Alexander Hoffmann