Electric motor with split stator core and method of making the same

DETAILED DESCRIPTION Therefore, an object of the present invention is to provide an electric motor in which the unbalance in the magnetic attractive forces acting between the unit cores can be restrained so that the vibration and noise are prevented, and a method of making the motor.
Another object is to provide an electric motor which is provided with a stator core including a plurality of unit cores and in which the iron loss can be reduced.
The present invention provides an electric motor comprising a rotor and a stator including a plurality of unit cores each of which has two ends.
The unit cores are disposed so that the ends of each unit core are adjacent to the ends of the neighboring unit cores respectively.
Each unit core includes a yoke section and a plurality of salient poles which are integral with the yoke section and on which concentrated windings are wound.
In this construction, each unit core is disposed so that the yoke section thereof is adjacent to the yoke sections of the neighboring unit cores and so that the salient poles thereof are separate from the salient poles of the neighboring unit cores.
Further, the salient poles are arranged circumferentially with a regular pitch.
Further, a number of the salient poles of each unit core is equal to a number of phases of the windings multiplied by any integer.
Additionally, each of the portions of the unit cores adjacent to each other is set so as to assume an angular position where a multiple obtained by multiplying a pitch angle of the salient poles agrees with a multiple obtained by multiplying a pitch angle of magnetic poles of the rotor.
Upon excitation of the windings of the above-described motor, a rotating magnetic field is generated so that the rotor is rotated.
An amount of magnetic flux passing through each yoke section changes momentarily as the rotor is rotated.
However, when a plurality of salient poles are provided so as to correspond to each of the phases, the yoke sections of the stator core have at an interval of a predetermined angle portions where amounts of magnetic flux passing therethrough become the same