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 fluid assembly in a hydraulic circuit, comprising one or more reservoirs configured to store fluid. The fluid assembly also includes a pump configured to transport the fluid in the hydraulic circuit and actuate a load from a transmission of a motor vehicle, a pressure accumulator configured to collect pressure built up by the pump and actuate the load, and a valve system configured to allow fluid communication of the load with the pump.

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.

This clutch control device includes an engine (13), a transmission (21), a clutch device (26) configured to connect and disconnect motive power transmission between the engine (13) and the transmission (21), a clutch actuator (50) configured to drive the clutch device (26) and change a clutch capacity, a hydraulic circuit (63) provided between the clutch device (26) and the clutch actuator (50), an air bleeding device (64) configured to perform air bleeding of the hydraulic circuit (63), a control unit (60) configured to calculate a control target value of the clutch capacity, a control mode changeover switch (59) configured to enable a control mode of the control unit (60) to be switched to an air bleeding mode, and an air bleeding switch (65) configured to enable a hydraulic pressure of the hydraulic circuit (63) to increase in the air bleeding mode.

A method for controlling a friction clutch actuated by an actuation system using an actuation pressure ambiguously applied along an actuation path includes providing the friction clutch and the actuation system, detecting a time curve of an actuation processes of the friction clutch, and comparing the time curve with the actuation pressure to ascertain an unambiguous friction clutch actuation path. The method may also include using the time curve to determine whether the friction clutch is in an opening state or a closing state and whether the actuation pressure is applied to an opened friction clutch actuation path or a closed friction clutch actuation path, and starting from a set actuation pressure, carrying out a directional control of the friction clutch by specifying the actuation pressure.

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.

Methods and systems for operating a plurality of electrical loads are described. In one example, the systems include electrical circuits for operating solenoid valves of a transmission that may be operated to simultaneously control two or more clutches for engaging and disengaging transmission gears. The systems and method may reduce hardware costs.

A disconnected, hydraulic disc coupling (4) in an AWD vehicle with a hydraulic cylinder (14) for its actuation is to be quickly connected or engaged. The effective piston area in the cylinder (14) is for that reason reduced during the connection phase.

The invention relates to a hydraulic circuit (1) of a torque transmission device, wherein at least two, in particular closed in a non-actuated state (normally closed), clutches (2, 3) of the torque transmission device can be element (12, 13) of the hydraulic circuit, wherein in a clutch opening state, every clutch valve element (12, 13) is connected to a high-pressure line (30) that is applied with the pressure of a high-pressure hydraulic accumulator (31) and/or generator (32), by means of a pressurisation line (22, 23) for the deflection of the clutch (2, 3), and in a closing state, same is connected to a low-pressure tank (40) by means of a tank line (42, 43, 44, 45, 46, 47, 48, 49) for releasing a deflection pressure, and wherein the tank lines (42, 43, 44, 45, 46, 47, 48, 49) of the clutch valve elements (12, 33) are guided to a safety valve (50), in particular by means of a common collection tank line (41), which safety valve can be switched in such a way that the tank lines (42, 43, 44, 45, 46, 47, 48, 49) can be applied with the pressure of the high-pressure line (30).

A hydraulic actuation device for a motor vehicle friction clutch has a manually actuatable master cylinder, that has a master pressure chamber which, in a rest position, is fluidically connected to a reservoir. The master cylinder is connected to a slave arrangement that is functionally connected to the motor vehicle friction clutch. A pressure line connects the master pressure chamber to the slave arrangement and in which incorporates an electrically actuatable valve arrangement with an electrically actuatable proportional valve and, connected in parallel, a first check valve which blocks in the direction of the master pressure chamber. A motor pump is connected, on the input side, to the reservoir and can be connected, on the output side, to the pressure line between the valve arrangement and the slave pressure chamber through a second check valve that blocks in the direction of the motor pump.