Abstract: A magnetic path is formed, in response to the rotation of a motor, by a magnetic detector (24 or 26) (more exactly, a magnetic wire (70)), a magnetic pole of the magnet (22), which is placed counter to each magnetic detector, and the rotating shaft (20). The magnetic wire (70) is formed of a magnetic material capable of causing a large Barkhausen jump. Whenever the magnetic pole opposite each magnetic element changes in response to the rotation of the motor, the direction of magnetic field constituting the magnetic path changes precipitously and a pulse signal in response to the change is outputted from the magnetic detector. Since the direction of magnetization of the magnetic wire (70) changes with a change in magnetic flux density received from a magnet (22), an induced electromotive force occurs due to a change in magnetic flux received by a detection coil. This makes enables the magnetic detector to output pulse signals without power supply.

Abstract: Each of the paired brush devices includes a brush in sliding contact with a commutator, a brush arm holding the brush, and a brush base to which the brush arm is fixed and which has a base hole. The pair of brush devices are disposed such that a line connecting the centers of the pair of brushes inclines in relation to a line connecting the centers of a pair of magnets. Each of the brush arms of the brush devices is disposed on the outside of the corresponding brush base at a location where the brush arm is fixed to the brush base, and one of the brush arms is bent from the outside of the corresponding brush base toward the inside thereof while being passed through the base hole to intersect the brush base.

Abstract: A side wall of a motor casing is formed into a polygonal shape such that flat side portions and corner portions located at respective corners between the side portions are continuously joined together. A field magnet, which has an outer circumferential shape approximately coinciding with the inner circumferential shape of the motor casing, has magnet side portions and magnet corner portions, and has a rib provided on outer circumferential surfaces of the magnet side portions. The magnet is disposed, through press-fitting, within the motor casing such that at least the rib comes into contact with the inner circumferential surface of the motor casing, wherein the magnet side portions, excluding the rib, are formed such that small clearances are formed between the magnet side portions and the side portions of the motor casing.

Abstract: A sensor magnet holder is mounted on a motor shaft, and a sensor magnet is provided relative to a magnetic induction sensor on the non-moving side for obtaining a signal indicative of a rotational position of the motor shaft. The sensor magnet holder integrally forms a cylindrical portion, a flange portion of a terminal end of the cylindrical portion having a large diameter, a magnet rear end holding portion of the other terminal end of the cylindrical portion and a plurality of snap fit board portions. A shaft press fit portion is formed on an internal diameter of the flange portion. The plural snap fit board portions extend from the cylindrical portion in an axial direction of the motor shaft. A magnet front end holding portion is formed at an extending tip over an outer diameter surface of each of the snap fit board portions.

Abstract: In the present invention, driving torque outputted from a motor portion is transmitted to a worm from a motor shaft, further to a helical gear from the worm, and is taken out to the outside from an output shaft which rotates together with the helical gear with a fixed shaft fixed to a gear box as a center. This fixed shaft is constructed in a hollow and cylindrical shape having an opening in which one end portion thereof has been opened, and a ceiling surface in which the other end portion thereof has been closed, and one end portion of this fixed shaft is subjected to dislocation preventive work, and is fixed to a gear box made of resin by pressing-in or insert molding. The other end portion of the fixed shaft is formed with the dislocation preventive structure of the output shaft and the helical gear installed to the fixed shaft.

Abstract: A cooling fan includes a fan ring to be attached to an end surface of a rotor core near the outer circumference thereof, and a plurality of fins connected to the fan ring. The fan ring has positioning leg portions provided on an end surface thereof facing a thrust direction. The fan ring is positioned in relation to the rotor core through insertion of the positioning leg portions into core slots of the rotor core. The fan ring has wire accommodation recesses which are formed on the end surface of the fan ring facing the thrust direction and communicate with the core slots.

Abstract: The present invention is used with a stopper mechanism for mechanically stopping the rotation of a motor. A pair of brushes is disposed such that a line which passes through the center of a rotor and connects the centers of the paired brushes is offset by a predetermined angle from a line which connects the centers of paired magnets. A commutator is disposed in such a manner as to be offset from a reference position by the same angle as the predetermined angle by which the paired brushes are offset. The predetermined angle falls within a range between an angle obtained by dividing 70° by the number of pairs of stator poles and an angle obtained by dividing 290° by the number of pairs of stator poles. Specifically, in the case of two stator poles, the predetermined angle falls within a range of 70° to 290° inclusive. In the case of four stator poles, the predetermined angle falls within a range of 35° to 145° inclusive.

Abstract: A DC motor 10 includes: a housing 12 having a polygonal cross section; a magnet 20 provided along the inner circumference of the housing 12 and having magnetic poles at the corners of the housing 12; a shaft 22 configured to be inserted into the housing 12 along the axial line of the housing 12; an armature 24 secured to the shaft 22 and provided to face the magnet 20; a commutator 26 fitted to the shaft 22 so as to be coaxial with the armature 24; a columnar carbon brush 30 provided in alignment with the radial direction of the commutator 26 such the end surface of the brush is in sliding contact with the outer circumference of the commutator 26; and a biasing member provided in the housing 12 and configured to bias the carbon brush 30 toward the commutator 26. The carbon brush 30 is provided at a position along the circumference of the housing 12 where the maximum length of the carbon brush 30 is ensured.

Abstract: An object of the present invention is to provide a commutator or brush material for a small electric DC motor which enables a lengthened operating life of a spindle motor for a DVD controlled using a pulse current. A commutator material for a small electric DC motor in accordance with the present invention is characterized by being composed of 6.0 to 10.0 wt % of Cu, 1.0 to 5.0 wt % of ZnO, and a balance of Ag and in that Cu metal particles and ZnO particles are dispersed in an AgCu matrix. A brush material for a small electric DC motor in accordance with the present invention is characterized by being composed of 0.1 to 5.0 wt % of MgO and a balance of Ag and in that MgO particles are dispersed in an Ag matrix, or is characterized by being composed of 5.0 to 15.0 wt % of Ni and a balance of Pt and in that Ni is dissolved in a Pt matrix.

Abstract: The present invention enables firm fixation between a motor casing and a casing lid at low cost through employment of a simple structure without need to use adhesive. A casing lid made of resin is fixedly fitted to an opening portion of a motor casing made of metal. Grooves or depressions are provided at the bottoms of a plurality of fixation portions provided on the casing lid at constant intervals in the circumference direction thereof. Bend portions at the opening portion of the motor casing are caused to bite into the grooves or depressions of the casing lid fitted into the opening portion of the motor casing, whereby the motor casing and the casing lid are fixed together.

Abstract: A motor includes a tubular housing having flat side walls along each side of rectangular joined with each other by joining sections, a magnet, having magnet poles in the jointing section, disposed along the inner peripheral surfaces of the housing, a shaft inserted along the axis of the housing, an armature fixed to the shaft in such a position as to be opposite to the magnet, a commutator mounted on the shaft, a carbon brush in sliding contact with the outer peripheral surface of the commutator, and electrical components provided within the housing. The electrical components in the longer direction are arranged nonparallely with all the sides of the housing.

Abstract: A small-sized motor includes a field magnet attached to an inner circumferential surface of a metallic motor casing and having four or more magnetic poles. The field magnet is formed of a single ring-shaped magnet member having a predetermined thickness with respect to the radial direction and a predetermined length with respect to the thrust direction. At each of portions between the magnetic poles formed through magnetization, the magnet member has a thin portion having a reduced thickness with respect to the radial direction, the thin portion being formed by cutting the magnet member from the radially outward side. The magnetization is performed in the radial direction so as to alternately form S poles and N poles in the circumferential direction. At each of portions between the magnetic poles, the magnet member may have cut portions formed at opposite end portions of the magnet member with respect to the thrust direction.

Abstract: A photo sensor module includes a holder made of resin and a light-emitting element and a light-receiving element accommodated in the holder. A printed circuit board is fixed to a flat side wall portion of a motor. The resin holder has a guide portion which is formed integrally therewith and which comes into contact with an end surface and a bearing-holding portion of an end bell. The printed circuit board is fixed in a state in which the guide portion is sandwiched between the bearing-holding portion and the printed circuit board while being brought into contact with the end surface of the end bell, whereby the photo sensor module is positioned in thrust and radial directions of the motor.

Abstract: An inner-rotor-type brushless motor includes a bus bar which connects together U-phase, V-phase, and W-phase windings and connects them to output wires. The bus bar includes, as conductive members, three external terminals connected to first ends of the windings and one Y-connection terminal for connecting second ends of the windings together. The external terminals and the Y-connection terminal are disposed on the body of the bus bar such that the Y-connection terminal and the external terminals are located on one side on the circumference of the bus bar body, whereby the bus bar body has a circumferential region where the conductive members are not present. A sensor bard carrying a position detection sensor is attached the bus bar body such that the position detection sensor is located in the circumferential region where the conductive members are not present.

Abstract: A plurality of coils wound around a stator magnetic-pole core are connected together and connected to output wires by use of a bus bar. The bus bar having a generally cylindrical body portion is disposed at one axial end of the stator magnetic-pole core, around which the coils are wound such that clearances are formed within magnetic-pole core slots, with an axial clearance formed between the bus bar and the coils. The body portion has such a radial dimension that at least a portion of the clearances within the magnetic-pole core slots is left uncovered. Air holes are formed in the motor housing on opposite sides of the stator magnetic-pole core to thereby form cooling air passages extending through the magnetic-pole core slots.

Abstract: A sensor magnet holder is mounted on a motor shaft, and a sensor magnet is provided relative to a magnetic induction sensor on the non-moving side for obtaining a signal indicative of a rotational position of the motor shaft. The sensor magnet holder integrally forms a cylindrical portion, a flange portion of a terminal end of the cylindrical portion having a large diameter, a magnet rear end holding portion of the other terminal end of the cylindrical portion and a plurality of snap fit board portions. A shaft press fit portion is formed on an internal diameter of the flange portion. The plural snap fit board portions extend from the cylindrical portion in an axial direction of the motor shaft. A magnet front end holding portion is formed at an extending tip over an outer diameter surface of each of the snap fit board portions.

Abstract: The metal-graphite brush of the present invention contains graphite, a metal, a lubricant, and bismuth or bismuth oxide in an amount of 1.0 wt. % to 3.0 wt. %. For example, the metal is copper, and the lubricant is molybdenum sulfide.

Abstract: Driving torque outputted from a motor portion is transmitted to a worm from a motor shaft, further to a helical gear from the worm, and is taken out to the outside from an output shaft which rotates together with the helical gear with a fixed shaft fixed to a gear box as a center. This fixed shaft is constructed in a hollow and cylindrical shape having an opening in which one end portion thereof has been opened, and a ceiling surface in which the other end portion thereof has been closed, and one end portion of this fixed shaft is subjected to dislocation preventive work, and is fixed to a gear box made of resin by pressing-in or insert molding. The other end portion of the fixed shaft is formed with the dislocation preventive structure of the output shaft and the helical gear installed to the fixed shaft.

Abstract: The rotation period of a motor is subdivided by edge interval times and a rate of change between a currently calculated edge interval time and an edge interval time calculated one rotation of the motor previously is calculated at the detection of each edge. Then the rotation period of the motor is calculated by multiplying a set reference period by the calculated rate of change.

Abstract: A brush holder device includes a brush including an integrally formed engagement portion; a brush arm having an engagement hole formed therein, the engagement hole assuming substantially the same shape as that of the engagement portion of the brush, and including brush contact portions located at laterally opposite edges of the engagement hole; and a holder. The holder has an engagement hole formed therein, the engagement hole assuming substantially the same shape as that of the engagement portion of the brush, and is fixedly attached to the brush arm such that the engagement hole is aligned with that of the brush arm. The engagement portion of the brush is press-fitted into the engagement holes of the holder and the brush arm, which are fixedly attached to each other, to thereby be fixed in place.