The present invention relates to a hydrostatic clutch actuator for a clutch, in particular a wet clutch, of a motor vehicle, wherein the clutch actuator has a drive unit, a master cylinder-piston-cylinder unit driven thereby, a hydraulic reservoir fluidically connected to the master cylinder-piston-cylinder unit, and a hydraulic system for actuating the clutch, wherein, by use of the master cylinder-piston-cylinder unit, hydraulic medium can be conveyed out of the hydraulic reservoir into the hydraulic system and the hydraulic system can be pressurized, and the hydraulic reservoir has an overflow, via which hydraulic medium can be discharged from the hydraulic reservoir and the hydraulic system.

A clutch actuator structure provided for an internal combustion engine and a hydraulic clutch mechanism for transmitting a rotational driving force of a crankshaft of said engine includes a clutch actuator for controlling an oil pressure for engaging and disengaging the hydraulic clutch mechanism. The clutch actuator structure ensures that noises generated at the times of operation of the clutch actuator for actuating a hydraulic clutch are prevented from being transmitted to the exterior. The clutch actuator structure includes an oil sump part for reserving oil provided in the periphery of a clutch actuator. The clutch actuator is disposed in the oil sump part.

A product that may include a clutch. A multi-chamber hydraulic unit may define a first chamber, a second chamber and a third chamber, each within the multi-chamber hydraulic unit. A first piston may separate the first chamber from the second chamber. The clutch may open in response to movement of the first piston. A second piston may separate the second chamber from the third chamber. A powered pump and a control valve may be provided wherein one of the second or third chambers may be in interruptible fluid communication with the powered pump through the control valve.

A hydrostatically operated clutch system having a hydrostatic clutch actuator for hydrostatically operating a clutch, in particular a pulse separation clutch of a hybrid drive, such that the hydrostatic clutch actuator is combined with a valve arrangement which is to be opened actively and enables the clutch to be engaged rapidly.

A clutch control device is provided for a four-wheel drive vehicle. The clutch control device is able to suppress the elevation of the temperature of the oil supplied to a friction clutch during two-wheel drive travel when the friction clutch is released. The clutch control device includes a dog clutch and an electronic control coupling. The friction clutch is housed in a coupling case. When the dog clutch and the friction clutch are released, a two-wheel drive mode is selected. The coupling case has a passage opening that is closed to retain lubrication oil in an oil chamber with respect to a clutch chamber that houses the friction clutch. When oil stirring conditions are met thereafter, the passage opening is opened and the lubrication oil is allowed to flow into the clutch chamber from the oil chamber.

A clutch control device is provided for a four-wheel drive vehicle. The clutch control device is able to suppress the elevation of the temperature of the oil supplied to a friction clutch during two-wheel drive travel when the friction clutch is released. The clutch control device includes a dog clutch and an electronic control coupling. The friction clutch is housed in a coupling case. When the dog clutch and the friction clutch are released, a two-wheel drive mode is selected. The coupling case has a passage opening that is closed to retain lubrication oil in an oil chamber with respect to a clutch chamber that houses the friction clutch. When oil stirring conditions are met thereafter, the passage opening is opened and the lubrication oil is allowed to flow into the clutch chamber from the oil chamber.