Patent ID: 9570949
Date: 2017-02-14
CPC Classifications: H02K

Claim:
1. An electric motor comprising: a ring-shaped stator that includes a field coil; a permanent magnet; a rotor holding the permanent magnet in a magnet holding portion of the rotor at an outer circumference of the rotor so that a cylindrical outer wall surface of the permanent magnet is exposed, the rotor being supported to be rotatable about a rotary shaft core in an inner space of the stator; the magnet holding portion including a magnet insertion portion which is more depressed in a rotary shaft core direction than an outer circumference of a rotor yoke configuring the rotor and a pair of regulation bodies integrally formed with the rotor yoke and extending toward a central side in an opening width direction with respect to an opening portion formed in an outer circumferential position of the rotor yoke in the magnet insertion portion, the permanent magnet being positioned in the magnet insertion portion; the cylindrical outer wall surface of the permanent magnet possessing a radius equivalent to that of the outer circumference of the rotor yoke, the permanent magnet also possessing a flat rear wall surface which is a side opposite to the outer wall surface, a pair of side wall surfaces which are both end portions in a circumferential direction of the rotor yoke, and a pair of engaged surfaces which are formed by partially notching the outer wall surface so as to cause the regulation bodies to fit and abut thereon at both end positions on the outer wall surface in the circumferential direction; and the magnet insertion portion being a groove-shaped portion possessing a bottom surface that faces the rear wall surface of the permanent magnet, the bottom surface of the groove-shaped portion possessing a width in the circumferential direction as measured between opposite circumferential ends of the bottom surface of the groove-shaped portion, the magnet insertion portion also including expansion portions possessing a groove configuration extending circumferentially beyond the opposite circumferential ends of the bottom surface of the groove-shaped portion of the magnet insertion portion, the expansion portions which possess the groove configuration being devoid of any part of the permanent magnet so that the expansion portions are empty, wherein a side of each expansion portion parallel to the rear wall surface is substantially coextensive with a respective one of the pair of regulation bodies.