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US 4,536,669 AGranted
Direct current motor
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorAkira Morishita
Life of this patent
Estimating the term…
Abstract
A d.c. motor comprises a cylindrical yoke, at least one set of field magnets of permanent magnets fixed to the inner peripheral surface of the yoke, an armature wound with armature windings so as to be surrounded by the field magnets, a commutator firmly mounted on a rotary shaft of the armature, a set of brushes being in slide-contact with the commutator, and a displacing means for shifting the position at which the brushes are made in slide-contact with the commutator in the counter direction of the rotation of the armature depending on rise in temperature of the d.c. motor.
Claims5
A d.c. motor which comprises:
- a cylindrical yoke;
- at least one set of field magnets consisting of permanent magnets fixed to the inner peripheral surface of said yoke, said permanent magnets having a magnetic flux which varies with temperature, the magnetic neutral point of said field magnets being deflected when said magnetic flux varies;
- an armature wound with armature windings so as to be surrounded by said field magnets;
- a commutator firmly mounted on a rotary shaft of said armature;
- a set of brushes being in slide-contact with said commutator;
- said brushes being mounted on a brush holder which is in sliding relation with said yoke;
- and
- a displacing means for shifting the position at which said brushes are made in slide-contact with said commutator by slidingly rotating said brush holder in the counter direction of the rotation of said armature so as to compensate for said deflection of said magnetic neutral point;
- said displacing means being actuated by a rise in temperature of said d.c. motor.
6 more elements
Dependencies are inferred from the claim text.