A vehicle transmission includes a hydraulic circuit and a control unit. The control unit is configured to: obtain (20) a target pressure specification; convert (26) the target pressure specification into a target volume flow rate; determine (42) a valve volume flow rate as a function of the target volume flow rate and as a function of parameters that represent system properties of the hydraulic circuit; determine (46) a pressure drop at a valve due to flow forces as a function of the valve volume flow rate; determine (48) a compensated valve output pressure as a function of the valve volume flow rate and the pressure drop; determine (58) the electric control current as a function of the compensated valve output pressure; and activate a valve with the electric control current.

A hydrodynamic friction clutch may include a rotatably mounted shaft, a drive disc non-rotatably fixed on the shaft, and an output body rotatably fixed on the shaft. The drive disc may include a radially extending annular transmission region for receiving a viscous fluid and via which the drive disc may be couplable to the output body for transmitting a torque, and an annular segment-shaped storage chamber for receiving the viscous fluid. The transmission region may be fluidically connected to the storage chamber via an inlet path and a drainage path. In the inlet path, a closable valve opening for controlling the quantity of the viscous fluid in the transmission region may be provided. The inlet path may include an annular segment-shaped communication passage, which may fluidically connect the storage chamber to the valve opening. The drainage path may fluidically connect to the inlet path at the valve opening.

A pressure control valve (1) 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 (F1) and a second spring (F2). The springs (F1, F2) and area ratios of the pressure control valve (1) 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 (1). 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.

A transmission system includes a fluid-coupling device, an electro-hydraulic control system, and a clutch. The fluid-coupling device includes an input coupled to an impeller, an output coupled to a turbine, and a stator disposed between the impeller and the turbine. The electro-hydraulic control system includes a flow valve disposed in fluid communication with the input and the output of the fluid-coupling device that is movable between at least a first position and a second position, at least one trim valve system fluidly coupled to the flow valve, and a solenoid disposed in fluid communication with the flow valve that is electrically controllable between an energized state and a de-energized state. The clutch is disposable in fluid communication with the flow valve and controllable between an applied position and an unapplied 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.

This clutch control device is provided with: a supply valve and a supply valve control unit, which control the supply of an operating fluid to a pressure chamber; a first discharge valve and a first discharge valve control unit, which control the discharge of the operating fluid in the pressure chamber; and a second discharge valve and a second discharge valve control unit, which control the discharge of the operating fluid in the pressure chamber. When it is determined that the engagement and disengagement switching of a clutch device 2, which is necessitated by the discharge of the operating fluid in the pressure chamber, is required, the first discharge valve is controlled to be opened and then the second discharge valve is controlled to be opened.

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.

Hydraulic-oil control devices are provided herein that perform hydraulic-oil supply control in a dual clutch device having a first clutch and a second clutch. A hydraulic-oil control device according to embodiments herein includes a first linear solenoid valve that adjusts hydraulic oil having a line pressure for a first hydraulic chamber and supplies the hydraulic oil thereto, a second linear solenoid valve that adjusts hydraulic oil having a line pressure for a second hydraulic chamber and supplies the hydraulic oil thereto, a shuttle valve that outputs the hydraulic oil having a higher pressure between the pressure of the hydraulic oil in the first hydraulic chamber and the pressure of the hydraulic oil in the second hydraulic chamber, and a switch valve that adjusts the amount of hydraulic oil supplied to a first space and a second space, according to the pressure of the hydraulic oil output from the shuttle valve.

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 rotor assembly for a rotary mixer is disclosed. The rotor assembly includes a main drive configured to rotatably drive the rotor assembly, a main drive clutch enclosed in a drivetrain housing of the main drive, an actuation valve operably coupled to the main drive clutch, the actuation valve configured to actuate the main drive clutch between at least a first position and a second position, a rotor drum, a rotor drive gearbox having an input and an output, the gearbox output operably coupled to the rotor drum, a main drive belt rotatably coupled to the main drive clutch and the rotor drive gear box input such that a rotation of the main drive clutch imparts a rotation on the rotor drive gear box, and a speed sensor operably coupled to the rotor drum, the speed sensor measuring a rotational speed of the gearbox and generating a rotor speed signal, wherein based on when the rotor speed signal is below a predetermined rotor speed threshold the actuation valve is activated to rotate the main drive clutch a predetermined amount between the first position and the second position.