To suppress vibration and noise by improving the lubricating state of a crankshaft.
This power transmission device comprises a crank journal 610 having molded web 620 and web 630, a bearing 640, and a thrust bearing 650. A spring 660 and a stopper 670 are attached to the thrust bearing 650. When the crankshaft is rotating at a low speed, the bearing 640 is constrained by a friction plate 632. The bearing 640 rotates integrally with the crank journal 610, so that the outer diameter of a rotating shaft becomes large. When the crankshaft is rotating at a high speed, the web 620 displaces by receiving a thrust load from a wing type flywheel. The bearing 640 is constrained by the stopper 670. Only the crank journal 610 rotates, so that the outer diameter of the rotating shaft becomes small.
Toshio Morita
Takao Matsuyama
Tadashi Muto