Power transmission system for vehicle

摘要

The present invention relates to a power transmission system for a vehicle of the type in which front and rear wheels are driven by a sole engine. In order to control the distribution of drive torque produced by the engine to front wheel side and rear wheel side of the vehicle according to a difference in rotational speed between both sides and in relative rotational direction between both sides, the power transmission system includes an oil pump adapted to be driven by a first rotational shaft which transmits a driving torque from an engine to front wheels of the vehicle and a second rotational shaft which transmits the driving force to rear wheels of the vehicle. The oil pump produces an oil pressure proportional to the difference in rotational speed and has at least two ports. A clutch mechanism couples the rotational shafts with each other by the discharge pressure of the oil pump and, the clutch mechanism is disposed between the rotational shafts. An oil pressure control system controls the discharge pressure fed from the oil pump to the clutch mechanism to adjust the coupling force of the clutch mechanism in accordance with the difference in the relative rotational direction between the pair of rotational shafts.