Minebea Company, Limited

Masaki Kagawa

Yuzuru Suzuki

Sakae Fujitani

Takayuki Yamawaki

Hiroyuki Furusaki

Yoshiyuki Aono

Kunitake Matsushita

Takayuki Matsui

Haruka Miyaji

Masato Hata

Tomoyuki Suzuki

There is provided an actuator including a motor and a case adapted to house the motor. In the actuator, an output shaft of the motor is supported by a structured configured such that an elastic member is disposed between the case and at least one end of the output shaft, wherein the elastic member is in contact with a portion of the case in an engaging manner whereby the elastic member is prevented from shifting relative to the case in the rotation direction of the output shaft, and also wherein the elastic member is in contact with a portion of the motor in an engaging manner whereby a body of the motor is prevented from shifting relative to the elastic member in the rotation direction of the output shaft.

Motor support structure and actuator incorporating same

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

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

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.

The present invention provides a rotor magnet with a claw pole type of actuator of a single phase structure and a magnetization method of the rotor magnet, in which detent and dynamic torques are sufficiently ensured, an angle range of rotational operation is wide, the cost is inexpensive and the characteristics are stable. In the actuator of such structure, the rotor magnet is rotatably arranged through a fine space inside an armature coil, wherein the rotor magnet comprises a single cylindrical type of magnet having a distribution pattern of a magnetic flux in which the magnetic pole peak position of at least one of the N and S poles is shifted stepwise in the axial direction thereof.

Actuator

An inexpensive, small, high-efficiency actuator having a single-phase claw pole structure permits easy assembly or winding and enables a rotor to act in a fixed direction by detent torque even in a deenergization mode. The actuator includes a stator yoke composed of a pair of substantially circular toroidal planar yokes formed of a soft magnetic material, polar teeth which axially protrude from inner peripheral edges of the respective planar yokes and which are disposed so that they face each other, extending in a circumferential direction, and a stator yoke that has a cylindrical ring provided on outer peripheral edges of the planar yokes; an armature being constituted by installing a coil formed by winding a magnet wire in a coil receiving section shaped like an annular recess formed by the planar yokes, the polar teeth, and the cylindrical ring of the stator yoke; and a stator assembly which has flanges with bearings provided on both end surfaces of the armature and in which a rotor provided with a magnet for a magnetic field composed of a permanent magnet being installed such that it faces the polar teeth of the stator with minute gaps provided therebetween; wherein the number of the polar tooth equals the number N of rotor magnetic poles (N is 2 or 4).

Actuator with number of stator teeth equal to number of rotor poles

The present invention provides, in a single phase-structure actuator, a rotor magnet structure having characteristics wherein detent torque is fully assured, and there is also a large rotation angle range. In a single phase-structure claw pole-type actuator,which constitutes an armature,constituted from stator yokes,which constitute a pair of donut-shaped flat yokes,comprising a Soft-Magnetic material, and pole tooth,which protrude in the axial direction from the inner rim of these flat yokes, and extend in the circumferential direction, and a cylindrical ring,which extends in the same direction as the pole tooth,on the outer rim of a yoke, and from a coil,which is formed by winding an insulating wire, and which is provided in a toroidal concave coil holder portion, which is formed from the flat yokes, pole tooth, and cylindrical ring of the stator yoke, and, in a stator assembly, having bearings,equipped flanges,at both end faces of this stator, causes a rotor,which is equipped with a field magnet comprising a permanent magnet rotor (hereinafter referred to as &ldquo;rotor magnet&rdquo; to face the pole tooth of this stator by way of a minute gap, the rotor magnet,is a cylindrical shape, and a plurality of magnets are connected in the axial direction, and the magnetic poles of each magnet are mutually shifted in the circumferential direction.

A stator structure enables a claw pole motor to be reduced in diameter and to highly increase its performance. In a stator structure of the claw pole stepping motor comprising a stator that constitutes magnetic circuits in yokes,and,made by sheet metal working of a soft magnetic steel plate and a rotor that is disposed inside the stator for rotation; pole teeth,made of soft magnetic material are provided as separate parts independent of the yokes,and,, and held at the inner circumference of a bobbin,made of polymeric material, thereby allowing easy manufacturing of a long stator or a stator with a small diameter for which the pole teeth,have difficulty, otherwise, in being well organized, at the same time allowing the area of cross section of the pole teeth,to be arbitrarily determined so as not to cause magnetic saturation, allowing to provide a high output power, allowing to determine the pole teeth,in the bobbin,so as not to disorder the arrangement of the pole teeth,which are responsible for the step angle accuracy, and thus allowing to accomplish high accuracy in step angle accuracy.

Stator pole teeth for a claw pole stepping motor

An iron core type cylindrical radial gap type motor structure, by having field magnetic poles generated by permanent magnets and, in opposition to these, salient poles generating a rotational magnetic field and arranged with their emission direction along the rotational axis, the shape of salient poles being approximately T-shaped in cross-section along the rotational axis direction, and I-shaped in cross-section at right angles to the rotational axis direction, the upper end of said T-shaped opposing the axial direction of the rotor magnets and the lower end being mechanically coupled and fixed to the stator ring, thus constructing the magnetic circuit of the armature, and where the relationship between the length L,of the said salient pole in the axial direction opposed to the field magnetic pole, and the length L,in the axial direction of the coil core section about which the coil is wrapped, satisfies the conditions 0.3*L,&lE;L,&lE;0.6*L,, and, furthermore, where the relationship between the thickness A,of the said salient pole in the circumferential direction, and the pitch P of the field magnetic pole, satisfies the conditions 0.4*P&lE;A,&lE;0.8*P.

Compact cylindrical radial gap type motor

A radial gap type cylindrical motor structure including a rotor which has a field magnet 13, a stator poles 20 having salient poles 18 opposed to the field magnet 13 of the rotor, a magnetic flux density adjusting yoke 21 formed in a cylindrical shape using a soft magnetic material and having salient poles 18, half the number of salient poles being projected as upper salient poles on an inner upper edge of the yoke inwardly at an equal angle and the remaining half of the salient poles being projected as lower salient poles on an inner lower edge of the yoke inwardly at an equal angle so as not to overlap the upper salient poles vertically, and driving coils 12 wound respectively around the upper and lower salient poles.

Radial gap cylindrical motor having an increased number of slots

A motor structure having an armature yoke 1 including a cylindrical portion and a plurality of salient poles 20 formed in the radial direction on the circumference of one end of the cylindrical portion, characterized by having a stator coil 5 formed by a concentrated winding provided around a salient pole portion 20', which is formed by joining the salient poles 20 of two armature yokes 1 together, and a motor structure characterized by having the above described structure and further having a salient pole piece 11 disposed on the front end of the salient pole portion in confronting relationship with a rotor magnet 2.

Radial gap type cylindrical motor

Salient poles made from soft magnetic steel plates have tip sections of approximately the same length as a rotor magnet. The salient poles are constructed with laminations in the circumferential direction, with axial dimensions adjusted with respect to the circumferential dimensions determined by the constraints of the winding to allow winding sections with a minimum required cross-sectional area so that magnetic saturation does not occur. These winding sections are inserted into coils wound with magnet wire, and press fitted into the stator which makes the magnetic circuit with the salient poles and forms the armature.

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Kitasaku-gun, Japan

Masaki Kagawa