Patent ID: 7452299

Claim:
A coupling apparatus applied to a differential unit including a differential case and a side gear arranged in the differential case, the differential case and side gear rotating relative to each other, the coupling apparatus comprising: a clutch member disposed between a side wall of the differential case and the side gear in an axial direction, the clutch member being rotationally engaged with the side gear through a coupling portion so as to rotate relative to the differential case integral with the side gear, and being movable in the axial direction; engagement portions integrally formed, one on the clutch member and another on the side wall of the differential case, the engagement portions engaging and interrupting with each other on the basis of the axial movement of the clutch member, thereby effecting locking and unlocking between the side gear and the differential case; and an electromagnet which executes the axial movement of the clutch member on the basis of a line of magnetic force passing through the engagement portions.