Zf Friedrichshafen Ag

Rainer Novak

Markus Terwart

Tobias Pfleger

Alexander Hoffmann

Markus Moosmann

Martin-Joachim Bader

Karl Locher

Andreas Feiner

Andreas Roedler

Florian Langenbacher

Karsten Kudermann

Dirk Friederich

Hans-Joachim Martin

Lukas Spath

Georg Ege

Frank Riever

Tobias Schmidt

A valve (V, V, V) includes a housing (VG) and a piston (VK) displaceably guided therein. A first end (VK) of the piston (VK) can be acted upon by a force, with the aid of which the piston (VK) is displaceable against a spring (F) acting upon a second end (VK) of the piston (VK). The valve (V, V, V) has four switching conditions, in which four ports (A, B, P, T) in the housing (VG) are selectively connectable to one another or blocked with respect to one another. In a first switching condition, none of the ports (A, B, P, T) are connected to one another. The spring (F) is configured in such that, in the absence of an application of force onto the first end (VK), the piston (VK) is held in a position, which corresponds to the first switching condition of the valve (V, V, V).

Valve, hydraulic system and motor vehicle gearbox

A hydraulic system (HY) for a motor vehicle transmission (G) includes at least one pump (P), two pump output lines (P, P) for supplying a first pressure circuit () and a second pressure circuit (), and an electromagnetically actuated, first pressure control valve (EDS), the inlet (EDS) of which is connected to the first pressure circuit () and the outlet (EDS) of which is connected to a first control surface (PVC) of a spring-loaded shut-off valve (PV). The shut-off valve (PV) is configured for connecting, in a non-actuated condition, the second pump output line (P) to the second pressure circuit () and, in the condition actuated via the first control surface (PVC), disconnecting the second pump output line (P) from the second pressure circuit (). A motor vehicle transmission (G) including such a hydraulic system (HY) and a drive train including such a motor vehicle transmission (G) are also provided.

Hydraulic system for a motor vehicle transmission

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 pressure back-up valve () includes a release piston () movable between first and second stop positions and a closing body () movable to a closing position in which this separates first and second connection pressure chambers () when the release piston () is in a first stop position. The release piston () moves the closing body (), in the second stop position, into an opening position. The release piston () is pressurizable on a first pressure surface (A) from a first side via a third connection pressure chamber () and on a second pressure surface (A) from a second side via a second connection pressure chamber (). The closing body () is pressurized, in the closing position, from a first side via the second connection pressure chamber () on a first pressure surface (A) and from a second side via the first connection pressure chamber () on a second pressure surface (A) of the closing body ().

Pressure back-up valve

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 pressure control valve () includes a pressure port (P), a consumer port (A), a tank port (T), and a piston (K) which is displaceable counter to the force of a first spring (F) and a second spring (F). The springs (F, F) and area ratios of the pressure control valve () are designed such that the pressure port (P), in the non-pressurized condition, is connected to the consumer port (A) via an opening cross-section of the pressure control valve (). An opening cross-section between the pressure port (P) and the consumer port (A) decreases depending on the pressure at the consumer port (A), and, upon attainment of a limiting pressure at the consumer port (A), the consumer port (A) is connected to the tank port (T). A related hydraulic system (HY) and a related motor vehicle transmission (G) are also provided.

Pressure control valve

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 actuating a valve device as a function of a characteristic curve including actuating the valve device with a dither superimposed on a target value (i_EDS) with such a frequency that the operating condition of the valve device follows the actuation corresponding to the characteristic curve (v_kk). The method further includes determining, with the characteristic curve (v_kk), the output values ('1', x) which correlate with the target values (i_EDS) at inflection points of a harmonic oscillation impressed upon the valve device with the dither, and determining further output values as a function of the output values ('1', x). The amplitude of the dither is predefined such that, during an actuation of the valve device, one of the inflection points lies in a first or second characteristic curve range (v_kkor v_kk, v_kkor v_kk), and another inflection point lies in a third characteristic curve range (v_kkor v_kk).

Method for actuating a valve device on the basis of a characteristic curve

A multi-speed transmission with hydraulically actuated shift rods, wherein an actuating pressure (p_B) is applicable by a valve device () and shuttle valves (C toD) to piston chambers (A toB) of pistons (to), the actuating pressure being adjustable by valves (). The piston chambers (A toB) can be brought into operative connection with a low-pressure region () by the shuttle valves (C toD) and a prefilling valve () or by the shuttle valves (C toD), the valve device (), and the valves (). Each of the shuttle valves (C toD) has a spring assembly (E toF), by which the shuttle valves (C toD) are held below a pressure threshold of the actuating pressure (p_B) in an operating state that connects the piston chambers (A toB) to the low-pressure region () by the prefilling valve ().

Multi speed transmission device with hydraulically actuated shift rods

A method for operating a transmission () with a hydraulic system comprising a variable capacity hydraulic pump, the method comprising determining during operation, a current hydraulic fluid volume requirement for actuating the transmission () and for temperature controlling and lubricating components of the transmission (); setting the delivery volume of the hydraulic pump in a manner dependent on the currently determined hydraulic fluid volume requirement of the transmission (), the delivery volume of the hydraulic pump, provided for temperature controlling and lubricating the components, being guided at least partially through a heat exchanger; wherein the delivery volume of the hydraulic pump is varied in a manner dependent on a temperature of the hydraulic fluid to an extent which sets that part of the delivery volume flow of the hydraulic pump which is to be guided via the heat exchanger.

Control method for a transmission with hydraulic system comprising a variable displacement pump

A method for determining a conveying capacity of a hydraulic pump includes opening a blockable flow cross-section in order to connect a pressure side of the hydraulic pump to an area of the hydraulic system through the flow cross-section after operating the hydraulic pump driven at a defined rotational speed. The flow cross-section is configured with the hydraulic pump such that an entire conveying volume flow provided by the hydraulic pump is guided through the flow cross-section when the flow cross-section is open. The method further includes comparing a change to an operating state of the transmission resulting from opening of the flow cross-section to a reference change to the operating state and determining the conveying capacity of the hydraulic pump as a function of a deviation between the change to the operating state and the reference change to the operating state.

Flow output determination method for a hydraulic pump in a transmission hydraulic system

A transmission includes a hydraulic system connected to a hydraulic pump and to an additional hydraulic pump. A secondary pressure circuit is connectable to a primary pressure circuit with a system pressure valve. A pressure side of the hydraulic pump is coupled directly with the primary pressure circuit and connectable to the secondary pressure circuit with the system pressure valve. A pressure side of the additional hydraulic pump is coupled directly with the secondary pressure circuit. The pressure side of the hydraulic pump proximate the secondary pressure circuit is connectable to a gear set, to a dual-clutch system and to a suction area of the hydraulic pump and the additional hydraulic pump by a valve device. The pressure side of the additional hydraulic pump is in connection with the gear set and is connectable with the dual-clutch system by the valve device.

Transmission device having a hydraulic system

A hydraulic actuating device is provided for a positive-locking shifting element of a transmission with a cylinder, in which a piston is arranged in a manner displaceable between a first end position and a second end position. The piston is a stepped piston and, with the cylinder, bounds an additional pressure chamber, which is connected to a first pressure chamber and/or a second pressure chamber through at least one hydraulic line. The volume of the additional pressure chamber decreases during an actuating movement of the piston in the direction of the first end position and increases during an actuating movement of the piston in the direction of the second end position. The degree of locking of the connection between the additional pressure chamber and the first pressure chamber and/or the second pressure chamber increases through the cylinder from a defined actuating path of the piston prior to reaching the first end position up to the first end position.

Hydraulic actuating device for a positive-locking shifing element of a 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 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.

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Bregenz, Austria

Rainer Novak