Minebea Company, Limited

Takayuki Yamawaki

Hiroshi Sano

Kunitake Matsushita

Yuzuru Suzuki

Toshihiko Nagata

Hiroyuki Furusaki

Kazuo Muramatsu

Masaki Kagawa

Sakae Fujitani

Taichi Nishio

Naoyuki Harada

Tohru Ohnuki

Hideki Matsuura

Hiroaki Ezure

Hiroshi Sakuma

Takashi Yoshikura

Michihiro Torii

A PM stepping motor includes: a stator assembly composed of two stator units which are axially coupled to each other with a molding resin material, and each of which includes: inner and outer yokes each having a plurality of pole teeth; a bobbin including inner and outer flanges; and a coil wound around the bobbin, thus providing two such inner yokes, outer yokes, bobbins and coils in total; a rotor assembly which includes a shaft and a magnet, and which is rotatably disposed in the hollow of the stator assembly; and two bearings to rotatably support the shaft of the rotor assembly, wherein the two bobbins are formed of the molding resin material to be consolidated with the two inner yokes, and wherein a plurality of protrusions are formed of the molding resin material to extend integrally from the outer flange of each of the two bobbins.

PM stepping motor having a stator assembly

In a small diameter stepping motor including two stator units each including a bobbin formed of an insulating material, each bobbin includes: a circular hollow cylinder portion having a winding; two flanges disposed respectively at the both ends of the cylinder portion; and a terminal structure disposed at one of the two flanges and including two terminal blocks and a pair of electrical contact members at which the lead-out lines of the winding are terminated, wherein the two terminal blocks are circumferentially shifted in position from each other with respect to the cylinder portion axis extend axially outwardly, and the terminal blocks of one bobbin intermesh with the terminal blocks of the other bobbin such that the terminal blocks of the one bobbin overhang a part of the winding wound on the other bobbin and vice versa when the two stator units are coupled to each other.

Small diameter stepping motor, bobbin used therein and manufacturing method thereof

A stator assembly is provided and includes a laminated core and a one-part insulator having cover walls for covering edges of the laminated core, wherein first projections and a second projection both having a height smaller than the difference between the height of the cover walls and the thickness of the laminated core are formed on one side surface of the insulator in such a manner as to make contact with a part of one axial end side surface of the laminated core, whereby a gap which corresponds to the projection distance of the first and second projections and which serves as a clearance space for chips scraped by the edges of the laminated core from the surfaces of the cover walls is provided between the insulator and the laminated core, resulting in ensuring that the insulator is snap-fitted on the laminated core in good shape.

Stator assembly

A stepping motor includes: a stator which includes a cup-like first (outer) yoke having a plurality of notches formed at its bottom plate, a second (inner) yoke, and a bobbin having a coil wound therearound and housed in the annular hollow space formed by the first and second yokes; and a pair of bearings each of which includes a hollow-cylindrical main body and a flange structure having a plurality of protrusions, and is attached to the stator such that the protrusions engage with the notches of the first yoke thereby preventing the bearing from rotating relative to the first yoke, and such that the protrusions make contact with a flange of the bobbin thereby precisely positioning the bearing relative to the first yoke with respect to the axial direction, which prohibits any portions of the bearing from protruding axially outwardly beyond the bottom plate of the first yoke.

Stepping motor

A rotor includes: a magnet having a circular cylinder shape and having a hole formed through its axial center, wherein the hole has in axial cross section a regular polygonal shape having flat portions and angle portions, and wherein a recess having a truncated cone shape is disposed at an axial end of the magnet such that the recess has its maximum diameter portion located at the axial end and has its minimum diameter portion communicating with the hole; and a shaft fitted in the hole of the magnet, wherein the outer circumference of the shaft makes contact with the flat portions of the hole of the magnet thereby forming a plurality of gaps between the outer circumference of the shaft and the angle portions of the hole of the magnet, and adhesive is filled in the gaps.

Rotor structure

In a stepping motor including two stators and a rotor having two magnets, three dimensional relations, specifically a relation of Lm/Ls, another relation of d/2Lm, and still another relation d/D, are optimally determined while satisfying their respective ranges: 0.35&#x2266;Lm/Ls&#x2266;0.45; 0.77&#x2266;d/2Lm&#x2266;1.10; and d/D&#x2266;0.45, where Lm is the axial dimension of the magnet, Ls is the axial dimension of the stator, d is the outer diameter of the magnet, and D is the outer diameter of the stator, whereby a space for accommodating a sufficient number of coil turns is secured maximally in the stator, and the inertia and the cogging torque of the rotor are reduced maximally, which leads to producing the highest possible torque at a high rotation speed range required.

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

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 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 stator assembly of a rotary electric device is manufactured and assembled at reduced cost with an enhanced level of precision. A stator assembly of a rotary electric device comprising a yoke provided with a plurality of stationary magnetic poles and a yoke plate bonded to said yoke by means of synthetic resin in a mold to form an integral unit for enclosing a stator coil is assembled by bringing an alignment pin arranged on a jig for combining the yoke and the yoke plate into engagement with a corresponding alignment sections of the yoke and the yoke plate to put the yoke and the yoke plate together in order to produce a unitary stator assembly and a step of placing the unitary stator assembly of the yoke and the yoke plate in an injection metal mold with said alignment section fitted to an alignment pin arranged in the mold for mutual engagement and injecting synthetic resin into the mold to bond the yoke and the yoke plate together.

Stator assembly of rotary electric device and method of assembling the same

The object of the present invention is to provide a rotary electric machine that provides bobbins with good assembling efficiency and allows no dislocation of the stator. A motor,comprises a case,, a stator,secured inside the case,, a rotor,formed into one piece with a rotating shaft,. The stator,comprises stator yokes,and the stator yokes are secured in a radial manner in the case,. Furthermore, resin,is filled in between the stator,and the case,with a space for the rotor being left. The stator yokes,comprise a salient pole,, a bobbin,for holding the salient pole,, and a magnetic wire,wound around the bobbin,. A collar,of the bobbin,is formed so as to contact each other with notches,formed on two, upper and lower edge portions. Accordingly, combining two bobbins,allows through-holes,penetrating the collar,thereof. This allows the stator to be firmly assembled, provides good assembling workability, and allows no dislocation owing to resin flowing when the resin is injected.

Rotary electric machine and bobbin thereof

The object of the present invention is to provide a rotary electric machine which has high assembly accuracy, high heat dissipating efficiency, and excellent durability at the bearing portion. A motor comprises a case, a stator secured within the case, and a rotor formed into one piece with a rotary shaft. The case is provided, on both end faces, with flanges, and one of the flanges is provided with a ball bearing. A stator is radially secured within the case, resin is filled in between the stator and the case with a space of the rotor being left, and a bearing housing and a boss are formed on one side. An open portion is formed in between ribs of the bearing housing, and inserting the bearing into the bearing housing causes a part of the bearing to be exposed through the open portion to fixedly contact with the flange. This allows supporting the bearing securely, and allows frictional heat generated, and the like, to dissipate to the outside via the flange. Furthermore, this allows mounting bearings with high accuracy, and reducing noise accompanying mechanical and electromagnetic vibrations.

Rotary electric machine and bearing structure thereof

A cup shaped base 12 and a cap 13 are coupled, therein coil spring 14 is accommodated to form a holder 11, and the holder is interposed between the bearing 3 of a rotor shaft 4 and a sleeve 5. Different from being directly mounted on the rotor shaft, since the base 12 is provisionally held on the rotor shaft, the operation efficiency at the time of assembling the motor is outstandingly increased.

Growing community of inventors

Shizuoka-ken, Japan

Takayuki Yamawaki