A hydraulic system including a hydraulically actuated clutch, a hydraulically actuated shifting piston, and a pressure source for actuating the clutch as well as the shifting piston. The movement of the shifting piston also controls a valve function which serves to open a connection from the pressure source to the clutch only when the shifting piston has reached one of its end positions.

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.

A clutch actuating device has an actuating cylinder with piston and rod-side chamber, a multiplier cylinder with piston-side and rod-side chambers separated by a piston, a rod(s) interconnecting the pistons, and a directional control valve. The valve has a pilot port, ports in fluid connection with piston-side and rod-side chambers of the multiplier cylinder, and a port in fluid connection with a secondary source. When a first fluid pressure (P1) from a first pressure source is applied to the pilot port and rod-side chamber of the actuating cylinder, a second fluid pressure (P2) is applied to the piston-side chamber of the multiplier cylinder by the secondary source. This results in the first and second fluid pressures (P1 and P2) acting on the piston of the actuating cylinder to produce a clutch actuation fluid pressure.

A hydraulic control system of double piston clutch device configured for an automatic transmission, which includes clutch drum connected to one rotation element, a clutch configured in the clutch drum and configured to transmit rotation power in connection with another rotation element through a clutch hub, and a double piston in which first and second pistons are disposed in series to operate the clutch by hydraulic pressure while a front end is disposed to correspond to the clutch, may include a first hydraulic chamber formed between the first piston and the clutch drum to receive the hydraulic pressure through a first passage hole in a sealed state; and a second hydraulic chamber formed between the first and second pistons to receive the hydraulic pressure through a second passage hole in the sealed state and the hydraulic pressure separately controlled is supplied to the first and second hydraulic chambers, respectively.

A dual clutch device is provided with a first piston for engaging a first clutch by using hydraulic pressure supplied to a first hydraulic chamber and disengaging the first clutch by using a first spring, a second piston for engaging a second clutch by using hydraulic pressure supplied to a second hydraulic chamber and disengaging the second clutch by using a second spring, first supply lines for supplying hydraulic pressure to the first hydraulic chamber and a second hydraulic canceling chamber, second supply lines for supplying hydraulic pressure to the second hydraulic chamber and a first hydraulic canceling chamber, a first valve for allowing or blocking the hydraulic pressure supply to the first hydraulic chamber and the second hydraulic canceling chamber, and a second valve for allowing or blocking the hydraulic pressure supply to the second hydraulic chamber and the first hydraulic canceling chamber.

A hydraulic clutch system for a motorcycle includes a foot pedal for engaging and disengaging a hydraulic clutch via hydraulic fluid in a first hydraulic fluid conduit and a hand clutch lever for engaging and disengaging the hydraulic clutch via hydraulic fluid in a second hydraulic fluid conduit. A solenoid or similar article switches the system between foot pedal and hand clutch lever control based on pressure in hydraulic lines extending from the foot pedal and hand clutch lever to the hydraulic clutch. A pressure switch, micro-switch or similar article communicates with, and activates the solenoid or other article to switch between lines.

A hydraulic circuit includes a clutch actuator operatively associated with a clutch that may be disposed in a transmission. A hydraulic fluid source supplies pressurized hydraulic fluid for the clutch actuator. To measure the filling rate of the hydraulic actuator, a reference actuator having a predetermined filling rate is disposed in parallel with the hydraulic actuator and in fluid communication with the hydraulic fluid source. If hydraulic pressure associated with the reference actuator does not correspond to the hydraulic pressure associated with the clutch actuator, a compensation valve can appropriately respond by selectively directing hydraulic fluid to or from the clutch actuator. In a further embodiment, the reference actuator and compensation valve may be replaced with an electrohydraulic valve utilizing feedback from the hydraulic pressure present at the inlet of the clutch actuator.

A method for controlling a hydraulic system for actuating a drive train device of a drive train of a motor vehicle includes a first volumetric flow of a pressure medium being provided by an electrically operated pump, and a slave cylinder piston of a slave cylinder being actuated along an actuation path, in a manner controlled by a switch valve, via a second volumetric flow generated from the first volumetric flow. A leakage in the hydraulic system is determined from a comparison of the first and second volumetric flows.

An assembly for driving a friction clutch, having a hydraulically driveable stepped piston, with: a pump driving the stepped piston, which has a working piston moveably arranged in a working chamber that divides it into first and auxiliary working chambers. The working piston is mechanically connected to an auxiliary working piston and hydraulically driveable via a second working chamber. A control valve is arranged between the stepped piston and pump. A first line path leads from the pump to the second working chamber, and a second line path leads from the pump to the first working chamber. The stepped piston has a working tappet which acts on the friction clutch. The first and second line paths are connected via a first line section of the supply line and a multi-port control valve, which has two valve positions, and the first line section is at least partially blocked in one valve position.

This clutch control device includes a clutch device (26), a clutch actuator (50), a hydraulic pressure circuit device (53), hydraulic pressure sensors (57, 58), a control device (60), and a control valve (56) for controlling a flow of a working fluid between the clutch device (26) and the clutch actuator (50). The hydraulic pressure sensors (57, 58) include an upstream side hydraulic pressure sensor (57) and a downstream side hydraulic pressure sensor (58). The control device (60) is configured to perform feedback control of the clutch actuator (50) using hydraulic pressure detection information of a side on which hydraulic pressure fluctuation is small, among the hydraulic pressure detection information of each of the upstream side hydraulic pressure sensor (57) and the downstream side hydraulic pressure sensor (58), in the case of driving the clutch actuator (50) toward a pressurization side and in the case of driving the clutch actuator (50) to a decompression side.