US 4,289,998 AGranted

Single phase DC brushless motor

AssigneeAstronautics Corporation of America

InventorGerald F. Dulin

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Abstract

The single phase DC brushless motor is particularly useful as a gyro motor in a turn coordinator for aircraft. Essentially, the motor comprises a permanent ceramic rotor magnet with diametrically oppositely disposed stationary stator windings and a "Hall effect" sensor or Hall cell positioned adjacent to the rotor and responsive to the permanent magnet poles of the rotor to generate a commutating switching signal. The Hall cell is very economical to use and is capable of driving transistor switches directly for the stator windings without problems of extensive amplification and drift previously experienced. The immediate advantage of such a sensor is the complete elimination of brushes and conventional commutating bars and all of the attendant problems associated therewith. Cost savings are further realized by the use of bobbin wound coils for the stator windings rather than laying the windings into slots. Laminations are thus avoided and by the use of a ceramic rotor still further savings are achieved.

Claims4

Dependent claims

A single phase DC brushless motor including, in combination:

(a) a permanent magnet rotor made of ceramic material;
(b) stator windings adjacent to the periphery of the rotor, said stator windings being bobbin-wound without laminations and stationarily positioned adjacent to diametrically opposite sides of the rotor;
(c) a sole Hall cell adjacent to the rotor and stationary relative thereto responsive to rotation of the rotor to provide a commutating signal for switching current passed to the stator windings in synchronism with the speed of the rotor whereby slip rings and brushes are eliminated, and
(d) a gimbal mounting the rotor for rotation, the gimbal being mounted for turning movement about a gimbal axis at right angles to the axis of rotation of the rotor, the gimbal axis being coaxial with the stator windings so that magnetic flux interaction between the stator windings and the rotor is invariant with turning of the gimbal, said Hall cell being positioned juxtaposed to a central portion of the rotor, the axial width of the ceramic material making up the permanent magnet being such that the degree of turning of the gimbal is not sufficient to remove the influence of the magnet on the Hall cell, whereby the motor can function as a gyroscope.

1 more element

Dependencies are inferred from the claim text.