DC motor having enhanced startability
AssigneeDenso Corporation
InventorTakashi Hirabayashi
Life of this patent
Estimating the term…
Abstract
A dc motor is provided which is equipped with brushes each of which is urged by a spring pressure into constant abutment with a commutator surface. A plurality of protrusions are arrayed on the commutator surface in a direction perpendicular to a direction in which a commutator is to be rotated and extend over a whole of a circumference of the commutator surface. Each of the protrusions is defined by two side walls arrayed adjacent each other. At least one of the two side walls of each of the protrusions is oriented to be inclined at a preselected angle to the orientation of the spring pressure. The preselected angle lies within a range of 20° to 70°. This ensures the stability of the abutment of the brush with the commutator surface, thus enhancing the startability of the dc motor.
Claims11
A dc motor comprising:
- a yoke forming a magnetic circuit;
- an array of permanent magnets disposed along an inner circumference of said yoke;
- an armature disposed inside said array of permanent magnets to be rotatable;
- a commutator provided to be rotatable together with said armature, said commutator having an outer circumferential surface;
- a brush riding on a commutator surface that is the outer circumferential surface of said commutator, said brush being urged elastically in a given direction into constant engagement with the commutator surface;
- and
- a plurality of protrusions that are arrayed on the commutator surface in a first direction perpendicular to a second direction that is a direction in which said commutator is to be rotated and extend over a whole of a circumference of the commutator surface, each of the protrusions being defined by two side walls arrayed adjacent each other in the first direction, at least one of the two side walls of each of the protrusions being oriented to be inclined at a preselected angle to the given direction in which said brush is urged elastically, the preselected angle lying in a range of 20° to 70°.
Dependencies are inferred from the claim text.