Patent ID: 8672112

Claim:
A drive system for a vehicle, comprising: an engine including an output shaft; a transmission including an input shaft to which a driving force of the output shaft of the engine is transmitted, the transmission transmitting the driving force to driving wheels of the vehicle; a clutch mechanism including a first clutch portion arranged between the output shaft of the engine and the input shaft of the transmission and positioned at the output shaft, and a second clutch portion arranged at the input shaft, the clutch mechanism being switchable between a connected state where the first clutch portion and the second clutch portion are engaged with each other to transmit the driving force of the engine to the transmission and a disconnected state where the first clutch portion and the second clutch portion are disengaged from each other to block the transmission of the driving force of the engine to the transmission; and a clutch operation mechanism switching the clutch mechanism between the connected state and the disconnected state by supply and discharge of oil to and from the clutch mechanism, the clutch operation mechanism including a clutch drum supported by the input shaft or the output shaft and having a cylindrical shape to form a drum chamber, a piston dividing the drum chamber of the clutch drum into a spring chamber generating a driving force for engaging the first clutch portion and the second clutch portion with each other, and a pressurizing chamber generating a driving force for disengaging the first clutch portion and the second clutch portion from each other, a control valve being switchable between a first position allowing the supply of the oil to the spring chamber and a second position allowing the supply of the oil to the pressurizing chamber, a biasing member arranged in the spring chamber and exerting a biasing force in a direction in which the first clutch portion and the second clutch portion are engaged with each other, and a bore formed in the clutch drum to establish a connection between inner and outer sides of the spring chamber, the bore discharging the oil of the spring chamber from the inner side to the outer side in a state where a counteracting force against a centrifugal force acting in the pressurizing chamber is generated in the spring chamber.