EP0182702A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Brushless DC motor
Assignee: Digital Equipment Corp
•
Filing: 1985-11-06
•
Granted: —
•
Expires: 2005-11-06
Abstract
Abstract A brushless DC motor having a number of armature poles (38-52) which is neither a multiple nor a submultiple of the number of field poles (12-22), thereby providing a relatively high cogging-ripple frequency. The field pole faces, which are generally arcuate in cross-section, have centrally disposed depressions (12d-22d). These depressions reduce the torque exerted by the armature when pole boundaries of the armature pass by the centers of the field poles. This reduces both torque ripple and cogging ripple and it doubles the frequency of torque ripple.
Inventors
- 👤 Friedrich R. Hertrich
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 22:34
CPC Classifications
H; H02; H02K; H02K29/00; H02K1/00; H02K1/06; H02K1/22; H02K1/27; H02K1/2706; H02K1/272; H02K1/274; H02K1/2753; H02K1/278; H02K29/06; H02K1/12; H02K1/14; H02K1/146; H02K21/00; H02K21/12; H02K21/14; H02K21/16; H02K29/03; H02K3/00; H02K3/04; H02K3/18; H02K3/28; H02K3/46; H02K3/48
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
189 words
A multiple-phase brushless DC motor comprising: A. a field (10) (1) having a plurality of pairs of diametrically opposed main field poles(12 22), the number of such pairs corresponding with the number of phases of the electrical excitation of said motor, (2) having a coil (12c-22c) on each main field pole, the coils on each pole pair being connected in series to form a coil pair, the coils of each coil pair being connected so that current through the pair provides the same polarity in both of the poles of the pole pair, (3) with each main pole havinga main pole face with a generally arcuate cross section, the central portion of the cross section having a depression (12d-22d) extinding radially away from the face, B. an armature (8) having (1) a plurality of poles and (2) permanent magnets (38-52) for magnetizing the armature poles; C. the numbers of field and armature poles and the arcuate extent of the field poles being such that within any 180 degree sector no more than one armature pole boundary is opposite a space between two field poles at any given armature position.
Claim 2
Dependent Claim
189 words
A multiple-phase brushless DC motor comprising: A. a field (10) (1) having a plurality of pairs of diametrically opposed main field poles(12 22), the number of such pairs corresponding with the number of phases of the electrical excitation of said motor, (2) having a coil (12c-22c) on each main field pole, the coils on each pole pair being connected in series to form a coil pair, the coils of each coil pair being connected so that current through the pair provides the same polarity in both of the poles of the pole pair, (3) with each main pole havinga main pole face with a generally arcuate cross section, the central portion of the cross section having a depression (12d-22d) extinding radially away from the face, B. an armature (8) having (1) a plurality of poles and (2) permanent magnets (38-52) for magnetizing the armature poles; C. the numbers of field and armature poles and the arcuate extent of the field poles being such that within any 180 degree sector no more than one armature pole boundary is opposite a space between two field poles at any given armature position.
Claim 3
Dependent Claim
22 words
The motor defined in claim 1 in which the armature poles form a substantially continuous surface of the armature facing the field.
Claim 4
Dependent Claim
22 words
The motor defined in claim 1 in which the number of armature poles is greater than the number of main field poles.
Claim 5
Dependent Claim
50 words
The motor defined in claim 1 A. in which the arcuate extent of each of the main armature poles is greater than one-half of the field pole pitch and substantially less than the pole pitch, and B. including auxiliary poles (24-34) disposed in the gaps between the main poles (12-22).
Claim 6
Dependent Claim
79 words
The motor defined in claim 2 in which A. each main field pole face has an active region of one-half the pole pitch, B. when an armature pole boundary leaves an active region on a field pole face during rotation of the motor, another armature pole boundary enters an active region of another field pole face, so that during rotation of the armature a succession of armature pole boundaries pass over a succession of field pole face active regions.
Claim 7
Dependent Claim
48 words
The motor defined in claim 5 in which the number of armature and field poles is such that whenever an armature pole boundary enters an active region of a field pole face, a diametrically opposed armature boundary enters the active region of a diametrically opposed field pole face.
Claim 8
Dependent Claim
49 words
The motor defined in claim 6 including means for energizing each coil pair when armature pole boundaries enter the active regions of the pole faces associated with the coil pair and de-energizing the coil pair when the armature pole boundaries leave the active regions of the associated pole faces.
References Cited (Backward Citations)
DE2823208A1
Cited
DE8015057U1
Cited
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.