Patent ID: 8376105

Claim:
A lock-up clutch mechanism provided in a fluid transmission device comprising a pump impeller connected with an output shaft of a driving source through a cover member, a turbine runner disposed in face-to-face relationship with the pump impeller and connected with an input shaft forming part of a driven side member, and a damper mechanism having a first damper plate connected with the turbine runner, and a second damper plate connected with the first damper plate through a resilient member and relatively rotatable with the first damper plate in the state of the resilient member compressed, the lock-up clutch mechanism intervening between the cover member and the second damper plate and comprising: a lock-up piston formed in a disc shape and movable toward and away from the cover member in the axial direction of the input shaft, a multi-plate clutch disposed between a first sliding surface formed on the inner peripheral surface of the cover member and a second sliding surface formed on one side surface of the lock-up piston, the multi-plate clutch having one or more clutch plates including a first friction member frictionally slidable with the first sliding surface and a second friction member frictionally slidable with the second sliding surface, the multi-plate clutch being formed with no less than two sliding surfaces between the one side surface of the lock-up piston and the inner peripheral surface of the cover member, and a connecting member for connecting the lock-up piston and the second damper plate, the connecting member having a connecting portion connected with the second damper plate and extending from the connecting portion to the other side surface of the lock-up piston, and the connecting member being partly in face-to-face relationship with the second sliding surface across the lock-up piston, wherein the connecting member has a cylindrical portion extending in the axial direction of the input shaft to partly constitute the connecting portion splined to the radially outer peripheral portion of the second damper plate, and a hollow disc plate portion integrally formed with the axial end portion of the cylindrical portion and radially inwardly extending from the axial end portion of the cylindrical portion, the hollow disc plate portion being in face-to-face relationship with the second sliding surface across the lock-up piston.