Abstract: 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.

Abstract: A hydraulic system is provided, comprising 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.

Abstract: Method of controlling a hydraulic system for an all-wheel drive system, including an electric hydraulic pump, a control valve for directing hydraulic fluid to a load, and an accumulator in fluid communication with the pump and the valve. The method includes the steps of estimating a negative hydraulic-fluid leakage flow out of the accumulator. Using a predetermined model, estimating a negative hydraulic-fluid work flow through the valve, and estimating a first positive fluid flow from the pump into the accumulator. The above estimated negative hydraulic-fluid leakage flow, negative hydraulic-fluid work flow and positive fluid flow are added to a total flow communicating with the accumulator, and a value is obtained of the volume of the hydraulic fluid in the accumulator from the total flow communicating with the accumulator for controlling an operation mode of the pump.

Abstract: An accumulator for a hydraulic system, wherein the accumulator comprises a liner, a piston and a housing, that defines a pressure chamber, for receiving hydraulic fluid at high pressure, wherein the piston is biased towards an end position of the pressure chamber for interacting with the hydraulic fluid in the pressure chamber, and the piston is movable in a predetermined range for accumulating hydraulic fluid. The accumulator has at least one outlet port in a sidewall of the liner, which outlet port is covered by the piston in the predetermined range and is uncovered when the piston has moved a predetermined distance from the end position. A hydraulic system is also provided that comprises the above accumulator and an all-wheel drive system comprising the above hydraulic system. A method for de-airing an accumulator according to above is also provided.

Abstract: In a four-wheel drive motor vehicle with a primary drive axle and a secondary drive axle, at least one secondary drive axle coupling of the limited slip type is provided in the powertrain between the engine of the vehicle and the secondary drive axle. A primary drive axle coupling of the limited slip type is provided for the primary drive axle.

Abstract: An all-wheel drive system for a vehicle having an engine and a drive shaft is arranged between the drive shaft and front and rear propellable shafts. These shafts are interconnected by first and second clutches respectively, and the propellable shafts are coupled to front and rear wheels, for transferring torque from the drive shaft to the front and/or rear wheels. The all-wheel drive system further includes at least first and second actuators that are coupled to at least first and second clutches, where at least the first clutch is engaged by a spring and at least the first actuator is coupled for disengaging the first clutch when the first actuator is operated. The second actuator is coupled for engaging the second clutch when the second actuator is operated.

Abstract: The present invention relates to an all-wheel drive system for a vehicle having an engine and a drive shaft, and where the all-wheel drive system is arranged between the drive shaft and front and rear propellable shafts. These shafts are interconnected by first and second clutches resp., and the propellable shafts are coupled to front and rear wheels, for transferring torque from the drive shaft to the front and/or rear wheels. The all-wheel drive system further comprises at least first and second actuators that are coupled to at least first and second clutches, where at least said first clutch is engaged by a spring and at least said first actuator is coupled for disengaging said first clutch when the first actuator is operated. The second actuator is coupled for engaging said second clutch when the second actuator is operated.

Abstract: A device for transmitting torque between two rotatable, coaxial shaft members (1, 2) contains a clutch (35) between the two shaft members and engageable—to counteract rotational speed differential between the shaft members—by a hydraulic piston (18) under the control of an electrically controlled throttle or pressure valve (26), and a clutch pump (36) for supplying hydraulic pressure to the hydraulic piston, the clutch pump being driven by either one or both of the shaft members. The hydraulic piston (18), the valve (26), and the clutch pump (36) are connected in a hydraulic system also containing a feeder pump (31) for maintaining a certain base pressure in the system. The hydraulic system conditionally allows flow from the feeder pump (31) past the valve (26) to the hydraulic piston (18) irrespective of the flow from the clutch pump (36).

Abstract: A device for transmitting torque between two rotatable, coaxial shaft members contains a clutch between the two shaft members and engageable to counteract rotational speed differential between the shaft members by a hydraulic piston under the control of an electrically controlled throttle or pressure valve, and a clutch pump for supplying hydraulic pressure to the hydraulic piston, the clutch pump being driven by either one or both of the shaft members. The hydraulic piston, the valve, and the clutch pump are connected in a hydraulic system also containing a feeder pump for maintaining a certain base pressure in the system. The hydraulic system conditionally allows flow from the feeder pump past the valve to the hydraulic piston irrespective of the flow from the clutch pump.

Abstract: In a four-wheel drive motor vehicle with a primary drive axle and a secondary drive axle, at least one secondary drive axle coupling of the limited slip type is provided in the powertrain between the engine of the vehicle and the secondary drive axle. A primary drive axle coupling of the limited slip type is provided for the primary drive axle.

Abstract: A device for transmitting torque between two rotatable, coaxial shaft members contains a clutch between the two shaft members and engageable to counteract rotational speed differential between the shaft members by a hydraulic piston under the control of an electrically controlled throttle or pressure valve, and a clutch pump for supplying hydraulic pressure to the hydraulic piston, the clutch pump being driven by either one or both of the shaft members. The hydraulic piston, the valve, and the clutch pump are connected in a hydraulic system also containing a feeder pump for maintaining a certain base pressure in the system. The hydraulic system conditionally allows flow from the feeder pump past the valve to the hydraulic piston irrespective of the flow from the clutch pump.

Abstract: A device for transmitting torque between two rotatable, coaxial shaft members (1, 2) contains a clutch (35) between the two shaft members and engageable—to counteract rotational speed differential between the shaft members—by means of a hydraulic piston (18) under the control of an electrically controlled throttle or pressure valve (26), and a clutch pump (36) for supplying hydraulic pressure to the hydraulic piston, the clutch pump being driven by either one or both of the shaft members. The hydraulic piston (18), the valve (26), and the clutch pump (36) are connected in a hydraulic system also containing a feeder pump (31) for maintaining a certain base pressure in the system. Means are provided in the hydraulic system for conditionally allowing flow from the feeder pump (31) past the valve (26) to the hydraulic piston (18) irrespective of the flow from the clutch pump (36).