Patent ID: 11876408
Assignee: PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. An electric tool including a motor, the motor comprising:
a stator including a stator core and a plurality of coils;
a rotor configured to rotate with respect to the stator core; and
a coil bobbin,
wherein:
the rotor includes:
a rotor core having a circular cylindrical shape;
a plurality of permanent magnets; and
an output shaft held inside the rotor core,

the plurality of permanent magnets are arranged as spokes around a center of the rotor core,
the stator core includes:
an outer cylindrical portion having a circular cylindrical shape; and
a central core arranged inside the outer cylindrical portion,

the central core includes:
an inner cylindrical portion having a circular cylindrical shape; and
a plurality of teeth,

the rotor is arranged inside the inner cylindrical portion,
each of the plurality of teeth includes a body portion protruding outward from the inner cylindrical portion along the radius of the inner cylindrical portion,
with the coil bobbin attached onto the central core and the coils wound around the body portion via the coil bobbin, the outer cylindrical portion is mounted onto the plurality of teeth,
the rotor core includes a high magnetic resistance portion provided on a magnetic path of a magnetic flux generated by the plurality of permanent magnets,
the high magnetic resistance portion has higher magnetic resistance than a portion, surrounding the high magnetic resistance portion, of the rotor core,
the high magnetic resistance portion includes a thinned portion,
the thinned portion has a shorter dimension as measured along an axis of the rotor core than parts, surrounding the thinned portion, of the rotor core,
the rotor core is formed by stacking a plurality of steel plates one on top of another in a thickness direction,
the plurality of steel plates include two or more steel plates having respective thinned portions constituting the thinned portion, and
the two or more steel plates are stacked one on top of another such that the respective thinned portions of mutually adjacent steel plates do not overlap with each other in the thickness direction.