A method operates a drive train for driving a working machine with variable rotation speed. The method includes running up the electric drive machine from a standstill with evacuated hydrodynamic rotation speed/torque converter to a predefined value which indirectly characterizes the operating mode of the drive machine. Simultaneously with reaching the predefined value which indirectly characterizes the operating mode of the drive machine or with a temporal offset after reaching this, filling the hydrodynamic rotation speed/torque converter and driving the turbine vane wheel. Thereafter, the third element of the planetary gear mechanism is driven with a rotation speed which results from a superposition, defined by the planetary gear mechanism, of the rotation speed of the first element of the planetary gear mechanism connected to the electric drive machine and the rotation speed of the second element of the planetary gear mechanism which is indirectly connected to the turbine wheel.

A system for controlling fluid flow to and from a clutch includes a motor, a pump, and a valve assembly, which includes a housing defining an interior and a first orifice operably coupled to the pump, a second orifice operably coupled to the clutch, and a third orifice fluidly coupled to one of said first and second orifices. A piston is operably coupled to the motor, is disposed within the interior, is movable between a first position for allowing a fluid flow between the first and second orifices, a second position for obstructing the fluid flow between the first and second orifices, and a third position for limiting the fluid flow between the first and second orifices. A biasing member is coupled to the piston, and biases the piston toward the first position when the motor is off. When the pump is activated and a pressure proximate the first orifice is equal to a pressure proximate the second orifice, the motor is energized and moves the piston to the second position. When pressure proximate the second orifice exceeds a predetermined threshold pressure, the energized motor is turned off and the biasing member moves the piston to the first position, or power in the energized motor is reduced and the piston moves to the third position.

A system for controlling fluid flow to and from a clutch includes a motor, a pump, and a valve assembly, which includes a housing defining an interior and a first orifice operably coupled to the pump, a second orifice operably coupled to the clutch, and a third orifice fluidly coupled to one of said first and second orifices. A piston is operably coupled to the motor, is disposed within the interior, is movable between a first position for allowing a fluid flow between the first and second orifices, a second position for obstructing the fluid flow between the first and second orifices, and a third position for limiting the fluid flow between the first and second orifices. A biasing member is coupled to the piston, and biases the piston toward the first position when the motor is off. When the pump is activated and a pressure proximate the first orifice is equal to a pressure proximate the second orifice, the motor is energized and moves the piston to the second position. When pressure proximate the second orifice exceeds a predetermined threshold pressure, the energized motor is turned off and the biasing member moves the piston to the first position, or power in the energized motor is reduced and the piston moves to the third position.

A system for controlling fluid flow to and from a clutch includes a motor, a pump, and a valve assembly. The valve assembly includes a housing defining an interior. The housing defines a first orifice operably coupled to the pump and a second orifice operably coupled to the clutch. The valve assembly also includes a piston operably coupled to the motor and disposed within the interior of said housing. The piston is movable between a first position for allowing the fluid flow between the first orifice and the second orifice, a second position for obstructing the fluid flow between the first orifice and the second orifice, and a third position for limiting the fluid flow between the first orifice and the second orifice. The valve assembly additionally includes a biasing member coupled to the piston. The biasing member biases the piston toward the first position.

A system for controlling fluid flow to and from a clutch includes a motor, a pump, and a valve assembly. The valve assembly includes a housing defining an interior. The housing defines a first orifice operably coupled to the pump and a second orifice operably coupled to the clutch. The valve assembly also includes a piston operably coupled to the motor and disposed within the interior of said housing. The piston is movable between a first position for allowing the fluid flow between the first orifice and the second orifice, a second position for obstructing the fluid flow between the first orifice and the second orifice, and a third position for limiting the fluid flow between the first orifice and the second orifice. The valve assembly additionally includes a biasing member coupled to the piston. The biasing member biases the piston toward the first position.

A hydrodynamic machine has a working chamber that may be filled with a working medium and in which a bladed pump impeller and a bladed turbine impeller are arranged to hydrodynamically transmit torque and/or drive power from the pump impeller to the turbine impeller. A working medium inlet and a working medium outlet are provided for inputting and discharging the working medium in/out of the working chamber. A control valve is furnished in the working medium inlet or in a bypass. The control valve changes the working medium quantity flowing into the working chamber. The control valve is connected to the working medium inlet and/or the working medium outlet and actuated such that the flow cross-section of the control valve is variably adjusted as a function of the working medium pressure in the working medium inlet and as a function of the working medium pressure in the working medium outlet.

A vehicle includes a transmission having a torque converter, a device configured to generate line pressure, and at least one fluid path connecting the device in fluid communication with the torque converter. A controller is programmed to, responsive to an engine-off time exceeding a threshold and a parameter indicative of departure being present, command the device to generate line pressure so that fluid is supplied to the torque converter. The device may be a transmission pump or an accumulator.

A vehicle includes a transmission having a torque converter, a device configured to generate line pressure, and at least one fluid path connecting the device in fluid communication with the torque converter. A controller is programmed to, responsive to an engine-off time exceeding a threshold and a parameter indicative of departure being present, command the device to generate line pressure so that fluid is supplied to the torque converter. The device may be a transmission pump or an accumulator.

A method operates a drive train for driving a working machine with variable rotation speed. The method includes running up the electric drive machine from a standstill with evacuated hydrodynamic rotation speed/torque converter to a predefined value which indirectly characterizes the operating mode of the drive machine. Simultaneously with reaching the predefined value which indirectly characterizes the operating mode of the drive machine or with a temporal offset after reaching this, filling the hydrodynamic rotation speed/torque converter and driving the turbine vane wheel. Thereafter, the third element of the planetary gear mechanism is driven with a rotation speed which results from a superposition, defined by the planetary gear mechanism, of the rotation speed of the first element of the planetary gear mechanism connected to the electric drive machine and the rotation speed of the second element of the planetary gear mechanism which is indirectly connected to the turbine wheel.

A method operates a drive train for driving a working machine with variable rotation speed. The method includes running up the electric drive machine from a standstill with evacuated hydrodynamic rotation speed/torque converter to a predefined value which indirectly characterizes the operating mode of the drive machine. Simultaneously with reaching the predefined value which indirectly characterizes the operating mode of the drive machine or with a temporal offset after reaching this, filling the hydrodynamic rotation speed/torque converter and driving the turbine vane wheel. Thereafter, the third element of the planetary gear mechanism is driven with a rotation speed which results from a superposition, defined by the planetary gear mechanism, of the rotation speed of the first element of the planetary gear mechanism connected to the electric drive machine and the rotation speed of the second element of the planetary gear mechanism which is indirectly connected to the turbine wheel.