Minebea Company, Limited

Yamaha Motor Electronics Co., Ltd.

Yamaha Motor Electronics Kabushiki Kaisha

Toshihiko Nagata

Hiroshi Sano

Kunitake Matsushita

Takayuki Yamawaki

Tomonari Shiraishi

Toshihide Ootani

Hideyuki Kobayashi

Naoyuki Harada

Yasufumi Takagi

Kunitake Matsushite

Katsuya Esaki

A brushless motor includes a stator including teeth each including a constricted portion on which a coil is to be wound, and a tip end portion including a confronting surface that faces a rotor and having a width greater than that of the constricted portion. A spacer includes closure members disposed between adjacent ones of the tip end portions, and fitted to the teeth so that the confronting surfaces of the teeth are exposed toward the rotor.

Brushless motor and electric bicycle provided with the same

A driving unit includes a stator, a housing including a tubular section to accommodate the stator, a cover coupled to the housing to block an upper opening of the tubular section, and a bent wire rod defined by a wire to press the stator against the tubular section, the bent wire rod being arranged between a top surface of the stator and a rear surface of the cover while being compressingly deformed along an axis of the stator. The bent wire rod has an annular or substantially annular shape with an opened portion when seen along the axis, and includes projections projecting upward along the axis and depressions projecting downward along the axis being arranged alternately and successively. An elastic force from the bent wire rod causes the stator to receive a downward force along the axis. The stator is pressed against the tubular section to hold the stator in the housing.

Stator-fixed structure and driving unit

A driving unit includes a stator, a housing including a tubular section to accommodate the stator, a cover coupled to the housing to block an upper opening of the tubular section, and a bent wire rod defined by a wire to press the stator against the tubular section, the bent wire rod being arranged between a top surface of the stator and a rear surface of the cover while being compressingly deformed along an axis of the stator. The bent wire rod has substantially annular shape with an opened portion when seen along the axis, and includes projections projecting upward along the axis and depressions projecting downward along the axis being arranged alternately and successively. An elastic force from the bent wire rod causes the stator to receive a downward force along the axis. The stator is pressed against the tubular section to hold the stator in the housing.

A claw-pole type stepping motor comprises: a rotor assembly shaped substantially cylindrical, and having a center shaft; and a stator assembly composed of two cup-shaped stator units which are coupled to each other coaxially so as to axially sandwich the rotor assembly, and which each include a bobbin having a magnet wire wound therearound, and two pole tooth arrays magnetically connected to each other and shifted in phase from each other by an electrical angle of 180 degrees. In the motor, each stator unit further includes a cover ring which protects the magnet wire wound around the bobbin against resin injected when the stator unit is resin-molded for an integrated solid structure. The motor structured as described above can be successfully resin-molded so as to enable elimination of a motor case, thus achieving downsizing for the dimension of the eliminated motor case while maintaining a sufficient mechanical strength.

Claw-pole type stepping motor

In a motor, a shaft passes through a magnet of a rotor and is fixed to the magnet by way of a rotor sleeve formed by resin-molding between the magnet and the shaft. A resin-molded boss is fixed to a front end of a stator, has a center hole, and defines an inner surface continuous from the center hole and beveled so as to obliquely face a front end of the rotor sleeve. A plurality of bearing balls are rotatably disposed between the front end of the rotor sleeve and the beveled inner surface of the boss, thereby constituting a ball bearing which rotatably supports the shaft. Thus, the shaft is prevented from bowing, whereby the motor achieves a high rotational accuracy of the shaft without an additional bearing attached separately.

Motor with built-in bearing

A stepping motor comprises a rotor assembly and a stator assembly. The stator assembly includes first and second stator units arranged horizontally on a same plane. Each stator unit is composed of: upper and lower stator yokes, which are shaped substantially semi-annular, arranged squarely opposite to each other in parallel, each have a plurality of pole teeth formed along its inner circumference so as to surround the rotor assembly, and which are coupled to each other with their respective pole teeth opposing each other so as to intermesh; a coil for exciting, wound rectangularly, and having its axis located outside the rotor assembly so as to be sandwiched between the upper and lower stator yokes; and a spacer shaped substantially in rectangular parallelepiped, oriented parallel to the axial direction of the rotor assembly, and inserted through the coil.

Low-profile stepping motor having coils wound rectangularly

A low-profile stepping motor has a stator assembly structured such that first and second coil units are disposed flush with each other horizontally and are sandwiched between upper and lower stator yoke pieces each comprising first and second stator yokes which are punched out integrally with each other, are shaped symmetrically, and which each have a plurality of pole teeth along its semi-circular inner circumference. The upper and lower stator yoke pieces are fixedly put together via the coils such that hollow-cylindrical protrusions formed in the upper and lower stator yoke pieces are inserted into through-holes of first and second coil bobbins from the upper and lower sides, respectively, and have their abutting end surfaces welded, bonded or otherwise fixed to each other, whereby the coil units are surely held between the upper and lower stator yoke pieces.

Low-profile stepping motor with two coils arranged flush with each other horizontally

A claw-pole type stepping motor comprises: a rotor which is shaped substantially cylindrical, and which has a rotary shaft at its radial center; and two stators which are shaped like a cup, each have at least one magnetic coil, are coupled to each other so as to rotatably house the rotor with their magnetic coils located respectively toward both axial end faces of the rotor, and which each have two pole tooth arrays magnetically connected to each other such that magnetic phase difference therebetween at tips of respective pole teeth is 180 degrees in terms of electrical angle, and in the motor thus structure, three pipes of aluminum go axially through the two stators so as to hold together the two stators.

Claw-pole type stepping motor having radial dimension reduced without detriment to performance characteristic

A low-profile stepping motor comprises: an upper twin-stator yoke plate composed of first and second upper stator yokes; a lower twin-stator yoke plate composed of first and second lower stator yokes; first and second coil units fixedly sandwiched between the upper and lower stator yoke plates so as to be arranged horizontally flush with each other; and a rotor assembly including a cylindrical magnet and disposed between the first and second coil units. In the stepping motor, one of the upper and lower twin-stator yoke plates is structured such that one half of its pole teeth partitioned in half by a predetermined datum line and open spaces each residing between two adjacent pole teeth of the other half are positioned symmetrically about the predetermined datum line, whereby the one twin-stator yoke plate can be used in common to the other twin-stator yoke plate.

A low-profile stepping motor has a stator assembly structured such that first and second coil units are disposed flush with each other horizontally and are sandwiched between upper and lower stator yoke pieces each comprising first and second stator yokes which are punched out integrally with each other, are shaped symmetrically, and which each have a plurality of pole teeth along its semi-circular inner circumference. The upper and lower stator yoke pieces are fixedly put together by means of two studs lodged fittingly inside respective bobbins of the first and second coil units such that the studs have their both ends tightly engaging with holes formed in the upper and lower stator yoke pieces, whereby the coil units are surely held between the upper and lower stator yoke pieces.

A low-profile stepping motor comprises: a first stator unit including first upper and lower stator yokes each having a plurality of pole teeth which are formed along its semicircular inner circumference, and a first coil unit fixedly sandwiched between the first upper and lower stator yokes; a second stator unit including second upper and lower stator yokes formed as one piece integrally with the first upper and lower stator yokes, respectively, and each having a plurality of pole teeth which are formed along its semicircular inner circumference, and a second coil unit fixedly sandwiched between the second upper and lower stator yokes; a rotor assembly rotatably disposed in a circular open space defined by the pole teeth of the first and second stator units; and a spacer block disposed between the upper and lower stator yokes and adapted to surround the first and second coil units and the pole teeth.

A claw-pole type stepping motor which includes a stator in which coils are arranged in association with a pair of inner and outer yokes and a pair of pole tooth sections thereby forming a magnetic circuit; and a rotor magnet which is rotatably disposed opposite to the pair of pole tooth sections, each of the pair of pole tooth sections being prepared discretely from each of the inner and outer yokes by punching out a soft magnetic steel plate so as to form a piece having a belt portion and a plurality of pole teeth integrally connected to the belt portion and thereafter rolling into a cylindrical shape. Thus, it becomes possible to set arbitrarily individual dimensions of each of the pole teeth as required by the characteristics of a motor, thereby providing an excellent high output and miniature motor.

A stator structure of a claw-pole type stepping motor which has an outer stator yoke having a plurality of pole teeth; an inner stator yoke having a plurality of pole teeth which are intermeshed with the plurality of pole teeth of the outer stator yoke with a gap therebetween; a coil disposed around the circumferential periphery defined by the pole teeth; and a covering which covers the coil. The stator external walls are only partially formed so as to allow the covering to be exposed in regions where the stator external walls are not formed. The stator structure of the present invention enables a dimensional reduction in size of a motor by a dimension corresponding to double the thickness of the stator yoke material, without impairing the performance of the motor.

Stator structure for claw-pole type stepping motor

A bearing installation for a Floppy Disk Driver motor which is simple in structure and high in accuracy of a rotating action of a rotary shaft, thus hardly impairing the read and write characteristics of a Floppy Disk Driver device. A bearing installation for a Floppy Disk Driver motor includes a protective cap mounted to one side of the motor; a first pivot bearing arranged for free and axial movements on a rotary shaft of the motor relative to the protective cap; a thrust spring urging axially the first pivot bearing on the rotary shaft of the motor; the rotary shaft fixedly mounted on a rotor of the motor, and supported pivotally at one end by the first pivot bearing and at the other end by a second pivot bearing fixedly mounted on a platform on which the motor is installed; a lead screw joined to an outwardly extending portion of the rotary shaft from the motor; and a positioning bushing arranged through which the rotary shaft fixed to the motor extends without direct contact with and closely fitted into a positioning hole provided in a plate to which the motor is secured.

Bearing installation in a floppy disk driver motor

A bearing system in a motor for a floppy disk drive (FDD) apparatus includes a protective cap mounted to one side of the motor, a first pivot bearing arranged movable to and from the protective cap in an axial direction of a rotary shaft, a thrust spring provided for urging the first pivot bearing in the axial direction of the rotary shaft, the rotary shaft having a rotor fixedly mounted thereto and rotatably supported at one end by the first pivot bearing and at the other end by a second pivot bearing mounted to a base for installation of the motor, and an alignment bushing arranged through which the rotary shaft of the motor extends without direct contact and closely fitted into a positioning hole provided in a plate to which the motor is secured. The rotary shaft remains not in direct contact with (spaced apart from) the alignment bushing and, acting as a leadscrew, can thus rotate at a higher accuracy, eliminating intrinsic drawbacks of the FDD motor. In rotation, a thrust is exerted across the first pivot bearing in the motor to the rotary shaft and such wearing properties as between the thrust spring and the ball in the conventional system needs not to be accounted for. Also, the thrust will be lessened by a combination of the base portion of the first pivot bearing and the protective cap which both are made of low-cost synthetic resin.

Growing community of inventors

Shizuoka-ken, Japan

Toshihiko Nagata