Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1983-08-03
1985-05-21
Beha, Jr., William H.
Electrical generator or motor structure
Dynamoelectric
Rotary
310268, H02K 118
Patent
active
045188831
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an electrical stepper motor comprising on the one hand a permanently magnetized rotative part which is mounted on the motor shaft and presents a rotational symmetry about it, this part having a small thickness as compared to its outer diameter and being magnetized in the direction of its thickness so as to present on each of its opposite faces 2N magnetic poles of alternating polarity, N being a natural number, these poles being arranged regularly along an annular zone, and comprising, on the other hand, at least one magnetic stator circuit and at least two electric coils coupled with this magnetic circuit, each circuit comprising at least one air gap in which the magnetized part is placed, and at least two polar parts having an axial plane of symmetry and being arranged for co-operation with the magnetic poles of the magnetized part. Such motors are, for instance, described in the U.S. Pat. No. 4,330,727 of applicants. The structure of the magnetic circuits of these known motors generally does not allow obtaining optimum efficiency or an optimum relationship between the efficiency, the manufacturing costs and the space occupied by the motor. Furthermore, imperfections of the magnetization of the rotative part can have an unfavorable influence on the precision of the motor operation.
The present invention aims to improve the performance of a motor of the above mentioned type, and in particular to improve the efficiency of such a motor by reducing the losses in the magnetic circuits, as well as to obtain a reduction of the weight and of the space occupied by the motor, while allowing manufacturing in large quantities at a relatively low manufacturing cost. The invention further aims to improve the operation of the motor by equalizing the influence of the magnetic poles of the magnetized part.
To this effect, the motor according to the invention is characterized in that each magnetic stator circuit comprises a first and a second group of polar parts including each at least two polar parts, the axial planes of symmetry of the polar parts of each group forming between each other at least approximately an angle of 2k.pi./N, k being a natural number, and the respective axial planes of symmetry of a polar part of the first group and of a polar part of the second group forming between each other at least approximately an angle of (2r+1).pi./N, r being a natural number, the polar parts of said first group being coupled with at least one of said coils and the polar parts of said second group being coupled with at least one other of said coils, the coils coupled respectively with the polar parts of the two groups producing, in response to a given exciting current, magnetic fields having in the transversal direction of the magnetized part opposite directions for each of the two groups, each magnetic stator circuit comprising, or being coupled with, two yoke parts placed on either side of the magnetized part, so that the magnetic field produced in these circuits is substantially within the two space portions extending respectively above the magnetic poles of each face of the magnetized part.
The magnetized part can have substantially the form of a thin annular disk magnetized in the axial direction of the motor, the polar parts of the stator extending at least to the space portion above the annular magnetized zone of one of the surfaces of the disk.
According to a preferred embodiment, the polar parts of each stator circuit are arranged by pairs, the polar parts of each pair having respective axial planes of symmetry which are identical or shifted, one with respect to the other, by an angle not exceeding .pi./3N, two ends of the polar parts of each pair being arranged in facing relationship, so as to form an air gap in which the magnetized part is placed, the ends opposite to those forming the air gap being connected between each other by corresponding yoke parts and the coils being placed respectively around each assembly of polar parts of a same group placed on a same side of the magn
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patent: 3392293 (1968-07-01), De Boo et al.
patent: 3426225 (1969-02-01), Bakhuizen
patent: 3784850 (1974-01-01), Inaba et al.
patent: 4007387 (1977-02-01), Rustecki
patent: 4079018 (1978-03-01), Noack
patent: 4095150 (1978-06-01), Senckel
patent: 4155018 (1979-05-01), Oudet
patent: 4242623 (1980-12-01), Oudet et al.
patent: 4330727 (1982-05-01), Oudet
Beha Jr. William H.
Portescap
Rebsch D. L.
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