A method controls a hydraulic system for an actuation device and a cooling and/or lubricating device of a motor vehicle. The hydraulic system has a pump, multiple first actuation valves which are each arranged between a system rail connected to a pump outlet and a hydraulic consumer, as well as an additional valve which is arranged between the pump outlet and a coolant and/or lubricant supply line. The pump is switched between a normal operation and an enhanced operation according to an existing total energy demand of the hydraulic consumer. In normal operation, the pump is permanently driven and the additional valve is opened and closed to control pressure in the system rail. In enhanced operation, the pump is permanently driven, the additional valve is permanently closed and each of the actuation valves is operated according to an individual energy demand of the respective hydraulic consumer.

Method for determining a kisspoint of a clutch. A method is provided of determining a kisspoint of a clutch in a driveline of a vehicle comprising a. increasing a target clutch pressure of a clutch piston up to a first predetermined test target pressure, b. increasing the target clutch pressure up to an upper target pressure and subsequently keeping the target clutch pressure stable for a predetermined time interval, c. monitoring a parameter indicative for the filling of the clutch piston, e.g. the rotational speed of a pump, during the predetermined time interval, d. repeating steps a., b., and c. for at least one further predetermined test target pressure, and e. determining the kisspoint based on the monitored parameter indicative for the filling of the clutch piston.

A power transmitting component can include a friction clutch, a ram, a pump, a fluid storage device and a valve. The ram can have a piston chamber and a piston movable therein between a first and second position to engage the friction clutch. A first inlet/outlet of the pump can be fluidly coupled to a reservoir. The fluid storage device can hold pressurized hydraulic fluid. The valve can be fluidly coupled with the piston chamber, a second inlet/outlet of the pump, and the fluid storage device. When in a first mode, the valve can permit fluid communication between the pump and the fluid storage device, inhibit fluid communication between the piston chamber and the pump, and inhibit fluid communication between the piston chamber and the fluid storage device. When in a second mode, the valve can permit fluid communication between the pump, the fluid storage device, and the piston chamber.

The present disclosure describes a hydraulic control system comprising a first pressure chamber and a second pressure chamber, each pressure chamber configured to receive a hydraulic fluid, a first movable member configured to assume a position depending on a hydraulic pressure of the hydraulic fluid in the first pressure chamber and a second movable member configured to assume a position depending on a hydraulic pressure of the hydraulic fluid in the second pressure chamber, a hydraulic command circuit configured to provide the hydraulic fluid and to control the hydraulic pressure of the hydraulic fluid in the first pressure chamber and/or the second pressure chamber, having a switchable valve in fluid communication with the first pressure chamber, wherein the switchable valve is configured to be pilotable depending on the hydraulic pressure of the hydraulic fluid in the second pressure chamber.

Actuation of a hydraulic device that provides a hydraulic supply to a torque-transmitting device is provided. An electrically operated pump is operated in a first operating state. The first operating state; has a primary pump rotational speed that provides a first fluid pressure to the torque-transmitting device via a fluid tract. A switchover process is initiated to operate the electrically operated pump device in a second operating state based on a second fluid pressure and a second fluid target pressure. The second operating state has a secondary pump rotational speed that provides the second fluid pressure to the torque-transmitting device via the fluid tract. During operation of the hydraulic device, the secondary pump rotational speed for the switchover process is determined based on a first power value. The first power value includes electrical pump power of the pump device in a preceding switchover process.

A line pressure control method for a double clutch transmission (DCT) includes estimating a line pressure, which decreases with stoppage of an electric oil pump, based on a linear regression model using state variables of the DCT that are related to a line pressure change, and driving the electric oil pump when the line pressure estimated based on the linear regression model reaches a predetermined lower limit.

The present disclosure describes a hydraulic control system comprising a first pressure chamber and a second pressure chamber, each pressure chamber configured to receive a hydraulic fluid, a first movable member configured to assume a position depending on a hydraulic pressure of the hydraulic fluid in the first pressure chamber and a second movable member configured to assume a position depending on a hydraulic pressure of the hydraulic fluid in the second pressure chamber, a hydraulic command circuit configured to provide the hydraulic fluid and to control the hydraulic pressure of the hydraulic fluid in the first pressure chamber and/or the second pressure chamber, having a switchable valve in fluid communication with the first pressure chamber, wherein the switchable valve is configured to be pilotable depending on the hydraulic pressure of the hydraulic fluid in the second pressure chamber.

A clutch device includes a plurality of clutches; a plurality of cylinder chambers provided to respectively correspond to the clutches; a pump configured to discharge a hydraulic fluid; a plurality of control valves each of which is configured to control the hydraulic fluid supplied from the pump to a corresponding one of the cylinder chambers; and an oil passage that distributes the hydraulic fluid discharged from the pump, to the control valves. The oil passage includes at least one split point at which the hydraulic fluid discharged from the pump splits. At least one check valve is provided between the at least one split point and at least one control valve among the control valves, the at least one check valve being configured to block a flow of the hydraulic fluid in a direction from the at least one control valve toward the at least one split point.

A drive force transmission apparatus is mountable on a four-wheel drive vehicle switchable between a four-wheel drive mode that transmits a drive force of an engine to front wheels and rear wheels, and a two-wheel drive mode that transmits the drive force to only the front wheels. The drive force transmission apparatus allows adjustment of the drive force to the rear wheels, and includes a multi-plate clutch, a piston for axially pressing the multi-plate clutch, an actuator for axially moving the piston, and a control unit for controlling the actuator. Upon satisfaction of a predetermined condition that indicates a high probability of the vehicle needing to be switched from the two-wheel drive mode to the four-wheel drive mode, the control unit causes the actuator to displace the piston by a predetermined amount with respect to an initial position of the piston toward the multi-plate clutch.

The clutch control device comprises: a pump that feeds oil to a hydraulic clutch; a control part that controls the pump; an input-side oil channel through which oil suctioned into the pump from an oil tank passes; an output-side oil channel connecting the pump and the hydraulic clutch; a pressure sensor; a connecting oil channel connected to the input-side oil channel and the output-side oil channel; and a solenoid valve that interrupts or allows the flow of oil in the connecting oil channel. The opening degree of the valve can be adjusted. When a drive shaft and a driven shaft are connected by the hydraulic clutch, the control part adjusts the opening degree of the valve on the basis of the pressure of oil in the output-side oil channel and the number of rotations made by the driven shaft while monotonically increasing the number of rotations of the drive part.