Zf Batavia L.l.c.

Zf Friedrichshafen Ag

Zf Transmission Technologies, L.l.c.

Andreas Piepenbrink

Wolfgang Danz

Andreas Schwenger

Ralf Vorndran

Stefan Sommer

Bernd Fessler

Friedrich Reiter

Wolfgang Runge

Patrick Speicher

Thomas Rossmann

Peter Janssen

Steffen Braun

A hydraulic system of a CVT transmission of a motor vehicle is proposed, which has an oil pump for conveying oil from an oil sump to a variator comprising a first pulley set and a second pulley set. In each case, a valve mechanism is provided for controlling a pressure acting on the pulley set concerned. Between the valve mechanisms associated with the respective pulley sets is arranged a pressure selector valve, whose position determines which of the the valve mechanisms controls a main pressure to be delivered by the oil pump.

Hydraulic system for a CVT-transmission of a vehicle

A continuously variable transmission for a motor vehicle, possessing a variator (') with a primary V-pulley set (&#x2032;) and a secondary V-pulley set (&#x2032;). In this arrangement are a primary V-pulley disk (&#x2032;) and a secondary V-pulley disk (&#x2032;), which are axially slidable by hydraulic force for the controlled adjustment of a pressure can be, respectively, loaded with an oil flow through an electro-hydraulically controlled pressure supply apparatus (&#x2032;). The pressure supply apparatus (&#x2032;) is so designed, that the oil flow is brought to the V-pulley disks (&#x2032;) through a pressure line (&#x2032;) with at least one pressure controller (&#x2032;) and one pressure chamber (&#x2032;) with a variable volume (VV). The pressure chamber (&#x2032;) of the primary V-pulley disk (&#x2032;) can be connected to a primary chamber&#x2032;) of the cylinder (&#x2032;), and the pressure chamber (&#x2032;) can be connected with a secondary chamber (&#x2032;) of said cylinder (&#x2032;), in which, between the primary chamber (&#x2032;) and the secondary chamber (&#x2032;) a double action, reversible piston (&#x2032;) is placed for directing pressurized oil from a low pressure side to a high pressure side of the variator (&#x2032;) upon the shifting of said variator (&#x2032;).

Continuously variable transmission

The invention describes a method and a device for controlling a drive train of a motor vehicle with a drive assembly and a continuously variable automatic transmission with a variable speed gear, wherein an electronic control unit for controlling at least the continuously variable automatic transmission and an emergency device are provided, with this unit being activated in the event of failure of the electronic control unit and a constant pressure/force ratio being established in the variable speed gear. Pursuant to the invention, in the event of failure of the electronic control unit the frictional connection between the drive assembly and the continuously variable automatic transmission is interrupted before the emergency driving mode is made available through the emergency device by re-establishing the frictional connection.

Method and device for controlling a drive-line including a CVT

A method for protecting a variator in a continuously variable belt-type transmission of a motor vehicle, simultaneously with a calculation based on an engine signal containing the magnitude of the engine torque and subsequent conversion of a contact-pressure theoretical value, providing the added safety on the variator, that the contact pressure on the variator is measured by a pressure sensor and the maximum transmissible transmission input torque is calculated with reference to this value. The maximum transmissible transmission input torque is then compared with the engine torque to the transmission and in case the maximum transmissible transmission input torque is less than the engine torque, an engine interruption is effected.

Slip protection method for a belt-type variator of a CVT

Within the scope of the method for adjusting the ratio value for a continuously variable transmission having a variator, a minimum contact pressure force P , and/or P is continuously calculated for the two variator discs on the basis of the actual ratio and of the actual torque to be transmitted and according to the calculated contact pressure minimum force the primary or the secondary disc is determined as controlled variable to be used for the variator ratio, the controlled variable being determined by a comparison of the required pressure values P or P with the calculated contact-pressure minimum value in a manner such that if P &lE;P , the controlled variable changes from the primary to the secondary side and if the condition P &lE;P is fulfilled, the secondary side changes to the primary side, the primary side being the controlled variable at the start of the method.

Method for adjusting the ratio of transmission in a continuous variable transmission

Within the scope of the method for regulating the rotational speed difference of a switchable frictional engagement control, specially of a clutch or brake, in the driving train of a motor vehicle by means of a control closed loop with the desired rotational speed difference as reference input and the actual rotational speed difference as controlled variable, together with the clutch pressure or brake pressure to be adjusted, at least one other controlled variable is used, wherein the closed loop comprises a linear governor and damping members (TP , TP , TP ) in a manner such that the time shift of the damped variable per reading step does not exceed a predetermined value so that the exciting of the closed loop remains within a stable range for controlling.

Speed difference regulation of a switchable frictional engagement control

Within the scope of the method for controlling the engine rotational speed via the torque converter lock-up clutch during the starting and stopping phases of a motor vehicle having a continuously variable transmission combined with other elements of the drive train, the closing and opening of the torque converter lock-up clutch are used as implicit function so as to ensure optimum comfort via the most asymptotic adjustment possible of the rotational speeds gradients of engine and turbine during starting and by a soft, defined separation of the speed characteristic curves of the engine and turbine during stopping. When the vehicle is standing still the forward clutch is moved into standstill disengaged mode so that the torque converter lock-up clutch can be fully closed.

Engine speed control via the torque converter lockup clutch of a continuously variable drive

In a method for controlling the multiplication for a continuously variable transmission with electrohydraulic control by means of a control loop having a linear PID controller with the specified multiplication of the variator iv_soll as command variable, the actual multiplication iv as regulating variable and the multiplication changing speed as correcting variable, the correcting variable delivered by the PID controller is limited to limiting values determined by the design for an upshift and downshift wherein said limiting values are calculated form the limits determined by construction and from the operating-point dependent limits determined by volume flow and the intersection of both admissible intervals determined by construction and by volume flow is defined as admissible multiplication changing speed range.

Method for determining adjusting speeds in a continuously variable transmission

Within the scope of the method for including the temperature in the calculation of the definite, operating-point dependent maximum and minimum adjustment speeds in a continuously variable belt-drive transmission, the actual limiting values for the maximum possible adjustment gradient are continuously calculated in every operating state by a physical-mathematical pattern wherein the hydraulic routes of the variator, the clutches integrated in the transmission and the lubrication are modeled as laminar inserts and the route of the control unit leakage as coupled laminar and turbulent hydraulic transmission elements.

Method of calculating for the speed control of a CVT

Within the scope of the method for ratio control of a continuously variable automatic transmission of a motor vehicle by means of a control loop structure which contains a non-linear compensation member for the variator and controllers for the pressures of both hydraulic routes of the variator pulleys and the variator routes, the control loop structure contains an interference variable observer which generates an interference force F that reproduces the pattern precision wherein the interference force together with the set value for the adjustment gradient which is limited as result of external standards, forms the compensation member.

Method for ratio controlling or speed controlling

The device to control a continuously variable automatic transmission (CVT) having a first bevel pulley pair, upon an input shift and a second bevel pulley pair upon an output shaft and a belt drive organ extending between the bevel pulley pairs, wherein the movable parts of the bevel pulley pairs are displaced in an axial direction by electromagnetic actuators and hydraulic pressure regulating valves, as well as adjusting cylinders, comprises a closed hydraulic circuit regulated at a constant pressure so that leakage flows of the adjusting cylinders for the bevel pulley pairs and leakage flows of the pressure-regulating valves are delivered directly to a hydraulic constant pressure circuit such as the circuit provided for supplying the torque converter and to the secondary circuit serving for lubrication.

Device for controlling a continuously variable automatic transmission

Within the scope of the process for control of vehicle acceleration for a motor vehicle having a continuously variable transmission, the vehicle acceleration is controlled by the ratio adjustment in the continuously variable automatic transmission with a pattern-based control addition using a status assessment method for assessing the output torque.

Acceleration control for a vehicle with CVT

A method for ratio control for a continuously variable belt drive transmission with electrohydraulic control by means of a control loop with a linear PID controller with the theoretical ratio of the variator iv_theor. as command variable, the actual ratio iv as control variable and the ratio-change speed as correcting variable wherein the correcting variable delivered by the PID controller is limited to limit values subject to the design for an upshift and a downshift, a correction member is used which, taking into consideration internal and external system variables, corrects with the aid of a physicomathematical pattern the pattern error generated wherein to the equation based on the physicomathematical pattern

Control method for adjusting the transmission ratio of a CVT

A method for determining an intersection-torque in a driving line of a motor vehicle having an automatic transmission which is controlled by an electronic control mechanism having one microprocessor with several program modules, the intersection-torque is determined in a program module of the electronic transmission control mechanism and is approximately defined by a state description of uniaxial transmission dynamics with model recalculation. At the same time the numbers of revolutions (&ohgr;,J,J_drive) are used as state variables for a motor, the transmission and/or the vehicle.

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Meersburg, Germany

Andreas Piepenbrink