Patent ID: 7884515

Claim:
A power transmission unit comprising: an electric motor having a rotor arranged in an inner circumference of a stator and concentrically with the stator; and a transmission mechanism for transmitting power; wherein a protruding portion of a predetermined constructional element of the transmission mechanism protrudes toward the stator or the rotor side coaxially with the stator or the rotor; the rotor is loosely fitted onto an outer circumferential face of the protruding portion; a clearance is created between an outer circumferential face of the protruding portion and an inner circumferential face of the rotor, wherein a guide sleeve that guides the rotor in an axial direction is configured to be inserted into the clearance; and the protruding portion includes a guide portion on a portion of the outer circumferential face thereof closer to a base end side thereof than a leading end portion thereof, on which the guide sleeve is fitted in close contact.