In an electric motor (2) which includes four permanent magnets (12) and in which the number of teeth (20) and the number of slots (23) are set to 6, when a polar arc angle of the permanent magnet (12) is 1, and a skew angle of the teeth (20) and the slots (23) is 2, the polar arc angle 1 and the skew angle 2 are set so as to satisfy 501<70 and 0<220.

In an electric motor (2) which includes four permanent magnets (12) and in which the number of teeth (20) and the number of slots (23) are set to 6, when a polar arc angle of the permanent magnet (12) is 1, and a skew angle of the teeth (20) and the slots (23) is 2, the polar arc angle 1 and the skew angle 2 are set so as to satisfy 501<70 and 0<220.

An embodiment relates to a rotor and a motor including the same, the rotor comprising: a rotor core; coils wound around the rotor core; covers respectively arranged at the upper part of the rotor core, wherein the cover includes: a main body disposed at the rotor core; a plurality of blades arranged on the upper surface of the main body; and at least two first protruding parts protruding in the axial direction from the upper surface of the main body. Therefore, the rotor and the motor including the same can perform a balance correction operation.

A magnetic core of an electric motor includes a central portion and a plurality of teeth extending outwardly from the central portion, the teeth disposed along a circumferential direction of the central portion. Each tooth includes a tooth body, two neck portions and two crown portions, the neck portions respectively connecting the crown portions to the tooth body, the two crown portions respectively extending beyond opposite sides of the tooth body. Each of the two neck portions of each tooth has a minimum width which is 0.10.3 times of the width of the tooth body. The present invention further provides an electric motor that employs the magnetic core which can increase the peak value of the cogging torque of the motor.

A magnetic core of an electric motor includes a central portion and a plurality of teeth extending outwardly from the central portion, the teeth disposed along a circumferential direction of the central portion. Each tooth includes a tooth body, two neck portions and two crown portions, the neck portions respectively connecting the crown portions to the tooth body, the two crown portions respectively extending beyond opposite sides of the tooth body. Each of the two neck portions of each tooth has a minimum width which is 0.10.3 times of the width of the tooth body. The present invention further provides an electric motor that employs the magnetic core which can increase the peak value of the cogging torque of the motor.

A synchronous reluctance type rotary electric machine of an embodiment has a rotor core. The rotor core includes a plurality of poles, multi-layered hollow parts having a convex shape toward a side radially inward formed for each pole in cross section, and a bridge formed between each of the hollow parts and an outer circumferential surface thereof. When a boundary between two adjacent poles is a pole boundary, a groove is formed on at least one of both sides sandwiching the pole boundary at positions other than on the pole boundary on the outer circumferential surface of the rotor core.

A stator core including field slots housing field windings and armature slots housing armature windings is provided. Permanent magnets are housed in the respective armature slots. Field windings face to the permanent magnets directly or via the stator core on the outer and inner circumferential sides. A coil end of one of the armature windings straddles the predetermined one of the field slots and passes over the axial end face of each of the permanent magnets in the corresponding one of the field slots over which the coil end straddles.

A synchronous reluctance type rotary electric machine of an embodiment includes, a rotor core, a plurality of conductor bars, short-circuit rings, a stator core, and multiphase armature windings. The rotor core includes multi-layered hollow parts having a convex shape toward a side radially inward formed for each pole in cross section, and a bridge formed between each of the hollow parts and an outer circumferential surface thereof. The plurality of conductor bars are disposed in the respective hollow parts. The short-circuit rings connect the plurality of conductor bars together. Then, in all of the hollow parts of a second layer and subsequent layers other than the hollow part of a first layer which is at a position farthest from the rotation axis of the rotor core, the conductor bars are disposed at both end portions thereof close to the bridge at a predetermined distance from the bridge.

A hand held power tool that includes a housing, a power source input configured to receive power from a power source, and a brushed motor located within the housing. The brushed motor is configured to receive power from the power source input. The brushed motor includes a first primary stator pole including a first pole neck and a first pole arc, a second primary stator pole including a second pole neck and a second pole arc, a first stator interpole including a first interpole neck, and a second stator interpole including a second interpole neck. The first stator interpole and the second stator interpole are each positioned between the first primary stator pole and the second primary stator pole.

A brush motor having a 4-pole 24-slot 2-brush structure includes a motor housing, a plurality of stators provided at intervals on an inner circumferential surface of the motor housing, a rotor rotatably installed inside the stators, a plurality of commutators installed on a rotation center shaft of the rotor, and a plurality of brushes configured to supply electric power to the commutators, the rotor including a plurality of slots formed at intervals on an outer circumferential surface thereof and a plurality of coils wound in the slots. The number of the stators is four, the number of the brushes is two, the number of the slots is twenty four, and the number of the coils is twenty four.