Mabuchi Motor Co., Ltd.

Takaichi Mabuchi

Toru Yano

In a miniature electric motor for generating vibration, an output portion of a rotary shaft is formed into an irregular shape in cross-section other than a circular shape in cross-section. An engaging hole having a predetermined shape in cross-section, which corresponds to the irregular shape in cross-section of the output portion and which makes a vibrator to be kept under a relatively non-rotatable condition to the rotary shaft, is formed in the vibrator. The output portion is engaged with the engaging hole and the vibrator is positioned and held in a thrust direction relative to the output portion to thereby fix the vibrator to the rotary shaft. This motor is used as a vibration generator for a mobile phone and the like.

Miniature motor with vibrator secured to an irregular portion of the motor shaft

A method of the present invention for manufacturing a small-sized motor relates to cutting or grinding of a shaft end portion of a rotor into a noncircular shape over a predetermined length for establishing a mechanical coupling with a device to be driven. The cutting or grinding work is performed after a laminated core , a winding , a commutator , and a thrust bush are assembled on a shaft to thereby assemble the rotor. Alternatively, a process of cutting or grinding the shaft end portion into a noncircular shape is performed after a casing , an end bell to be fitted to an opening portion of the casing , and a rotor are assembled into a small-sized motor. Thus, the present invention provides a method for manufacturing a small-sized motor in which a shaft has a D cut formed thereon, enables determination of whether or not the D cut is to be formed on the shaft, at a later stage of a motor assembly process, to thereby eliminating the need to control the stock of shafts bearing the D cut, does not involve the need to orient shafts in the same direction in preparation for press-fitting of laminated cores of rotors to the corresponding shafts, and can prevent generation of scrapings when a thrust bush is press-fitted to a shaft.

Method for manufacturing small-sized motor

An armature ( ) for a miniature DC motor constitutes a rotor provided in an interior of a casing and armature windings ( ) are wound around an iron core ( ) in the form of a coil. In this armature ( ), insulators ( ) made of paper including at least ordinary paper and having an electric insulation property adhere to at least portions, of both end faces of the iron core ( ), on which the armature windings are wound. Thus, the iron core and the armature windings do not come into direct contact with each other.

Armature for a miniature DC motor

Electric motor

Brushgear for miniature motors comprising a pair of brushes each having brush shoes, made of electrically conduction metal strips, for making sliding contact with a miniature motor commutator, in which each brush shoe is bent into a V shape in cross section; ends of the feet of the V-shaped brush shoe being adapted to make sliding contact with the commutator, and the sliding positions of the brush shoes of the two brushes are disposed apart from each other by a predetermined distance in the axial direction of the commutator and/or in an inclined state in the axial direction of the motor rotating shaft at a predetermined angle with respect to the tangential direction of the commutator.

Brushgear for miniature motors

Brushgear having L-shaped brush arms, each consisting of a terminal strip and a commutator contactor strip, both being joined into one piece by lapping one on another and crimping a plurality of projections formed on the terminal or commutator contactor strip. The terminal and commutator contactor strips are made of materials suitable for each thereof. The brush arms are inserted into the grooves of brush holders provided on a case cover of a motor case and firmly held in position.

Leaf brushes for small electric motors having commutator slide surfaces for making electrical contact with a motor commutator and constructed so that a multiplicity of fine ridges are densely formed on the commutator slide surfaces.

Leaf brushes for small electric motor

A commutator device for miniature motors comprising commutator segments, each segment having an arc-shaped commutator part and a terminal part standing upright from the commutator part; the commutator part being mounted on an insulating cylinder and the terminal part being bent to hold a lead wire connected to an armature winding wherein the terminal part of the commutator segment has a neck portion at which the transverse crosssectional area of the terminal part is made smaller than the transverse crossectional area of other portions therof, and an arrangement for easily bonding the lead wire to the neck portion is provided so that the lead wire is held in position by bending the terminal part at the neck portion thereof, and welded to the terminal part with resistance welding.

Commutator device for miniature motors

A small electric motor having an insulating cylinder fixedly fitted to a rotating shaft of a motor rotor, a plurality of commutator segments disposed at equal spacing in the angular positional direction of the insulating cylinder and brushes for making sliding contact with the cummutator segments. Each of the commutator segments has a commutator terminal formed by bending an end of the segment and led out for external connection. The insulating cylinder has an enlarged diameter portion, on which adhesive reservoirs are provided. An electrically conductive adhesive is injected into the reservoirs and deposited in such a manner as to bridge the adjoining commutator segments.

Small electric motor

A small electric motor whose small case has a through hole through which a motor terminal can be taken out is disclosed. A first slot which is right-angled longitudinally to the through hole and extends to the side face of the small motor case is provided in the end of the small motor case where an opening of the through hole is provided, and a second slot extended from the first slot is provided in the side face of the small motor case. Furthermore, a first kick is provided in the bottom of the first slot and a second kick is in the side face of the second slot.

A small electric motor having brushes comprising brush bases supported by brush supporting portions provided on a motor casing and bent portions which are formed by bending a part of each brush so that commutator slide portions of the brushes come in elastic contact directly with a commutator at a predetermined angle, and characterized in that rigidity reinforcing portions for giving rigidity to the bent portions are provided and/or auxiliary supporting portions for supporting the lower sides of the brush bases at the bent portions are provided on the brush supports.

Small electric motor with reinforced brush holder

A small electric motor having a plurality of commutator segments disposed at equal intervals in the angular positional direction on an insulating cylinder fixedly fitted to the rotating shaft of a motor rotor, and brushes for making electrical contact with the commutator segments, wherein reservoirs for holding an electrically conductive mixture are provided by boring the insulating cylinder in such a manner that the reservoirs extend to the adjoining commutator segments, the electrically conductive mixture being injected into the reservoirs so that the mixture is deposited in such a manner that the mixture bridges each commutator segments and covers the intervening portions between the commutator segments, the reservoirs being disposed in the locations at which the commutator segments and the brushes do not contact.

A small electric motor having a plurality of commutator arcuate segments equally spaced in the direction of angular position on the rotating shaft of motor rotor, wherein conductive grease is coated on the commutator arcuate segments and the equally spaced gaps, and edges provided on the sliding portions of brushes are caused to press and contact the commutator by cutting the conductive grease film.

Electric motor with controllable mechanical wear and spark generation

A brush device for a small electric motor comprises an integrally formed commutator slide, a brush base and a terminal portion made of a thin material. A reinforcing piece is provided by bending the side edge of the base both to permit the brush device to be resiliently retained within a terminal insert hole formed in the motor case cover.

Brush device

A brush device for a small electric motor wherein a brush integrally constructed of a commutator slide, a brush base and a terminal extending from the brush base is inserted into a terminal hole provided on a motor case, and sharp burrs on the tip of a cut and raised piece provided on the brush base is caused to cut into the inside wall surface of the terminal hole so that the brush is securely fixed to the motor case.

Growing community of inventors

Matsudo, Japan

Takaichi Mabuchi