Patent ID: 8083043

Claim:
A clutch device for transmitting torque from an engine of a vehicle to a transmission, comprising: a clutch engaging portion including a plurality of plate members; a piston being disposed close to the clutch engaging portion, the piston having a hole penetrating from a first axial side of the piston to a second axial side opposite the first axial side facing the clutch engaging portion; a first oil passage having one end on a piston side; a second oil passage having one end on a clutch engaging portion side; and an operating oil supply unit configured to select clutch engaging states by switching between supplying operating oil from the first oil passage while draining from the second oil passage, and supplying the operating oil from the second oil passage while draining from the first oil passage, the clutch engaging portion being engaged as the operating oil is supplied to the first oil passage from the outside of the clutch device while the operating oil in the second oil passage is drained to the outside of the clutch device, the clutch engaging portion being disengaged as the operating oil in the first oil passage is drained to the outside of the clutch device while the operating oil is supplied to the second oil passage from the outside of the clutch device, the first oil passage communicating with the second oil passage through the clutch engaging portion when the clutch engaging portion is disengaged, and the operating oil being prevented from flowing between an upper side of the clutch engaging portion to a lower side of the clutch engaging portion when the clutch engaging portion is engaged.