JP4533904B2 - Permanent magnet rotating electric machine - Google Patents

Description

  The present invention relates to a rotating electrical machine such as a stepping motor combined with a hybrid permanent magnet rotor.

There is a demand for a rotating electrical machine such as a stepping motor that is small and has high torque and low vibration used in OA equipment. In order to solve this problem, one of the inventors of the present application has already obtained the following patent. This application relates to improvements to these prior patents.

Japanese Patent No. 3762981 US Patent USP67881260B2

1) In a rotating electric machine having a structure in which two unit rotors are closely and coaxially connected by a multipolar rotating electric machine such as a hybrid (hereinafter abbreviated as HB) stepping motor and their permanent magnets are magnetized in opposite polarities. 1 and 2 have four stator main poles and two-phase windings to eliminate the unbalanced electromagnetic force and higher torque and fewer coils than the two-phase eight main pole motor, thus realizing low cost. However, if there are four stator main poles, which are winding poles, the coil end becomes larger than that of the 8-main pole motor, and there is a problem when the motor is thin in the axial direction.
2) If the stator is made of, for example, a dust core, a recess may be provided in the stator core in the axial direction to absorb the coil end. In addition, there is a problem that it is difficult to mold with high accuracy.

The present invention is realized by the following means.
"Means 1"
A stack of magnetic plates is concentrically distributed and a part thereof in the axial direction is fixed with a non-magnetic material or with a magnetic material, and is opposed to the rotor through an air gap at the inner periphery. The outer peripheral portion is joined to the salient pole portion shorter than the axial length of the laminated body having m coils protruding from the annular magnetic body including the polygon to absorb the protrusion of the coil end in the axial direction. A rotating electrical machine that uses what has been done as a means.
"Means 2"
Means 1 in the m magnetic plate laminate has a plurality of magnetic teeth on the rotor a portion facing and the rotor had a uniformly plurality N _r number of magnetic teeth on its outer periphery magnetic magnetized in the axial direction a rotor having a so-called hybrid type rotor or a plurality N _r number of teeth which sandwiches a permanent magnet magnetized to 1/2 pitch Zurashi with axial tooth pitch from each other in a disc with two Two unit rotors holding the permanent magnets separated from each other by a half pitch of the tooth pitch are provided on a common rotating shaft, and the rotors adjacent to or adjacent to the two unit rotors are positioned at the tooth positions. A rotating electric machine comprising: a special hybrid type rotor having the same polarity and magnetized to the same polarity, or a cylindrical permanent magnet type rotor having _Nr number of pole pairs equally on the outer periphery thereof.
"Means 3"
A rotating electrical machine in which the stator annular magnetic body in means 1 and 2 is a powder magnetic body having a jaw portion for absorbing the coil end.
"Means 4"
The rotating electrical machine according to means 1 and 2, wherein the stator annular magnetic body is a laminated steel plate and the axial thickness is the same as the thickness of the salient pole part having a coil.
"Means 5"
A two-phase permanent magnet type rotating electrical machine in which means 1 to 4 is such that m is 4 and the number of rotor teeth is 4n ± 1.
"Means 6"
A three-phase permanent magnet type rotating electrical machine in which means 1 to 4 is such that m is 3 or 6 and the number of rotor teeth is 3n ± 1.

1) When the number of main poles is reduced, the torque is increased and the coil ends are absorbed by the present invention. In the case of an annular magnetic body formed of a dust core, the front and rear brackets supporting the bearing are flat because there are jaws on the outer periphery. A plate shape is possible and the structure can be simplified. Further, the iron core portion can reduce the iron loss.
2) In the case of an annular magnetic body formed by a laminated type of silicon steel plates, there are no jaws on the outer circumference, so the front and rear brackets supporting the bearings are not flat plates, but the material of the stator is silicon steel plate Can be unified. Alternatively, the front and rear brackets may be flat plates, and the coil portions may be exposed to reduce the temperature rise.
3) If the hybrid rotor is used in the present invention, high torque can be obtained. The teeth of the stator are stamped after punching out a silicon steel plate, so the width teeth can be reduced to the same size as the plate thickness, which is advantageous for high resolution multipole. If the rotor is a cylindrical magnet type rotor, the magnetic flux distribution becomes sinusoidal, so that a rotating machine with low vibration can be obtained.
4) If m = 4 in a two-phase system, it is simple, and a special hybrid rotor can provide a low-vibration, small-sized, high-torque rotating electrical machine without unbalanced electromagnetic force at low cost.
5) If m = 3 in the three-phase system, it is simple, and a special hybrid rotor can provide a low-vibration, small, high-torque rotating electrical machine without unbalanced electromagnetic force at low cost.

  This will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a motor unit A when the present invention is applied to a configuration of a special hybrid type rotor and a two-phase four-main pole, which is one of the forms that best exhibit the advantages of the present invention. FIG. 2 is a view as seen from the axial direction of FIG. 1 and clarifies the relationship between the rotor teeth and the stator teeth. The motor unit A is provided with end ring plates 2 for concentrically arranging four tooth portions 1 formed and laminated from silicon steel plates at intervals of 90 degrees. In the case of a non-magnetic material, the end ring plate 2 may be a disc having a hole at the center. However, in the case of a magnetic plate such as a silicon steel plate, four holes are provided every 90 degrees as shown in FIG. The magnetic flux is saturated and the magnetic resistance is increased to reduce the leakage magnetic flux from the rotor so that the interlinkage magnetic flux with the coil is increased. 2 can also support a bearing.
In FIG. 3, the four arms extending in the radial direction support the bearing 7. Special hybrid rotor plurality N _r pieces (15 pieces in 2) to each other 1/2 pitch of the tooth pitch of the permanent magnet rotor 25 and 26 have teeth and magnetized in the axial direction by two Zurashi In the same manner, two sets of rotors 27 and 28 are similarly set as the first unit rotor sandwiched between the two unit rotors, and the second unit rotor is sandwiched by ½ pitch of the tooth pitch. Provided, the rotors adjacent to or adjacent to the two sets of unit rotors are rotors having the same tooth position and magnetized to the same polarity. In this way, an unbalanced electromagnetic force is not generated even in the two-phase four main poles, and a rotating machine with low vibration can be obtained. The reason for this is explained in the cited document 1, and therefore the explanation is omitted here. Although the reason will be described later, a high torque can be obtained when the four-main pole stator is configured. The motor unit A in FIG. 1 includes these rotors, a bearing 12 that rotatably supports the rotor, an end ring 2 and four tooth portions 1. The present invention exhibits the functions of the rotating electrical machine and the features of the present invention when combined with the motor unit B described below.
FIG. 2 shows a two-phase system, in which four teeth 1 facing each other at 180 ° are one phase, and one-phase windings are excited by a winding current so as to have different polarities. . In this case, if the number of rotor teeth is selected to be 4n ± 1, it is desirable that the four teeth are symmetrically arranged at 90 degrees. In addition, the present invention can be applied to a configuration in which the tooth portion 1 does not have an inductor magnetic tooth and the number of poles is small. It is desirable to have it.

FIG. 4 is an example of an end ring different from that in FIG. 3 and does not support a bearing, so there is no radial arm. It is composed of a magnetic plate such as a silicon steel plate.
In order to prevent magnetic short-circuiting, four holes are provided every 90 degrees in the same manner as in FIG. 3 so that the magnetic flux is saturated and the magnetic resistance is increased to reduce the leakage magnetic flux from the rotor and increase the interlinkage magnetic flux with the coil. Yes. You may make the part thin instead of the hole. Although the name is an end ring, if the strength is not limited to both sides of the tooth portion 1, it may be appropriately added to the central portion or the like. If a part of the tooth stack is fixed with a magnetic material in the axial direction, magnetic leakage can be reduced. The end ring is a magnetic plate, and it is desirable that the plate thickness and width are small in order to reduce magnetic leakage.

FIG. 5 shows a coil in which four winding poles protrude in the radial direction by a motor unit A using the end ring 3 of FIG. 3 on both sides and the above-described special hybrid rotor combined with a substantially square annular dust core 4. 5 and a jaw portion for absorbing the coil end is provided to form a motor unit B. And the winding pole which protruded four places of the unit B couple | bonds with the outer periphery of the motor unit A, it unites | combines, and the function of a rotary electric machine is exhibited. In this case, the coil ends of the four coils are absorbed by the stator portion, which is advantageous for making a thin motor. The length including the four jaws is preferably the same as the axial length of the motor unit A. Although omitted in FIG. 5, the front and rear brackets are simple plate-like, and the coil 5 can also cover the bearings. In the case of a hybrid type stepping motor, in order to make a small air gap of about 0.05 mm, these end brackets are provided with appropriate protrusions or steps so as to guide the inner periphery of the magnetic tooth portion of the stator. You can also
FIG. 6 is a front view seen from the axial direction of FIG. 5 and is a view seen with one end ring 3 removed. Further, since the substantially square annular dust core 4 is symmetrical, part of the illustration is omitted and the illustration of the coil 5 is also omitted. The tooth portion 1 may be fixed by a resin mold.
For example, if the stator is made integrally with a dust core, a recess may be provided in the stator core in the axial direction in order to absorb the coil end, but then the small inductor-shaped magnetic teeth of the stator have strength. In addition, it is difficult to mold with high accuracy. In the present invention, the inductor-shaped magnetic teeth having a small stator are manufactured by punching a silicon steel plate with a press, so that the tooth width can generally be made equal to the thickness of the silicon steel plate. A 0.35 mm silicon steel plate can have a tooth width of 0.35 mm, and a high-resolution motor that is impossible with a stator integrally formed with a dust core is possible.

FIG. 7 shows another embodiment of the present invention in which another motor unit B is combined with the motor unit A shown in FIG. 1, and FIG. 8 is a front view seen from the axial direction of the end ring 3 on one side. FIG. Further, since the substantially square annular laminated iron core 4 is symmetrical, a part of the illustration is omitted, and the illustration of the coil 5 is also omitted. The stator annular magnetic body 6 constituting the motor unit B is a laminated steel plate, has no jaw portion like the dust core 4, is simply flat, has four salient pole portions around which a coil is wound, and has an overall axial thickness. It is the same as the salient pole part thickness having a coil. If the length of the coil 5 in the axial direction is equal to or less than the length of the motor unit A, a thin motor is possible. In the case of the ring-shaped magnetic body 6 formed by the laminated type of silicon steel plates, there are no jaws on the outer periphery, so the front and rear brackets supporting the bearings are not flat plates, but the material of the stator is made of silicon steel plates. Can be unified. Alternatively, as shown in FIG. 7, the front and rear brackets may be flat plates, and the coil portion may be exposed to reduce the temperature rise.

FIG. 9 is a front view of a conventional two-phase eight-main-pole hybrid rotary electric machine, and FIG. 10 is a cross-sectional view including its shaft. As will be described later, the torque of the four main poles is half that of the eight main poles. The normal hybrid rotor shown in FIG. 10 can be used in the present invention if the number m of m is 8 for a laminate of magnetic plates, since no unbalanced electromagnetic force is generated. Further, m may be 3 or 6 in three phases. In this case, if the number of teeth of the rotor is selected to be 3n ± 1, the tooth portions are preferably arranged equally at 120 degrees or 60 degrees. n is an integer of 1 or more.

A rotor obtained by alternately magnetizing N poles and S poles on the cylindrical permanent magnet shown in FIG. 11 may be used as the rotor of the present invention. In this case, since the magnetic flux is sinusoidally distributed from the hybrid rotor, low vibration rotation can be obtained. The number of pole pairs has a function equivalent to the number of teeth of the hybrid rotor. In other words, in the case of FIG. In this case, the unbalanced electromagnetic force is cancelled. In the case of Nr pole-pair cylindrical magnets, Nr = 4n ± 1 and n = 4. n is an integer of 1 or more.

The torque in the case where the same unit rotor is combined with the two-phase four main poles and the eight main pole stators of the cited patent document 1 has been described in the aforementioned patent document 1, but will be described again. The configuration of the present application is about half the torque of the two-phase four-main-pole motor shown in this Patent Document 1.
T1 = N NriΦm (1)
The torque for one phase is expressed by equation (1). Nr is the number of rotor teeth, N is the number of coil turns, i is the current, and Φm is the flux linkage with the coil of the permanent magnet flux from the rotor.
Both have the same wire diameter and the same total number of turns Nt. The total amount of magnetic flux generated from the rotor is equal to, for example, 48 when the number of teeth of both stators is equal to 48 (8 × 6 = 48 for 8 main poles, 4 × 12 = 48 for 4 main poles). Neglecting the magnetic resistance difference of the iron core, it can be approximated to the same value of Φt.
, N4, Φ8, Φ4, the following equation is established.

Φ8 = Φt / 8 (2)
Φ4 = Φt / 4 (3)
N8 = Nt / 8 (4)
N2 = Nt / 4 (5)

From the formulas (1) to (5), the torques of the 8 main pole 4 main pole machine, T8, T4 are as follows.

T8 = 2 * 4 (Nt / 8) Nri (Φt / 8)
= NtN _r iΦ _T / 8 (6)
T2 = 2 * 2 (Nt / 4) Nri (Φt / 4)
= NtNriΦt / 4 (7)

From (6) and (7), the 4-main pole machine can output about twice the torque of the motor of the conventional 8-main pole machine. However, in the case of a normal unit rotor, unbalanced electromagnetic force is generated in the 4-main pole machine, and noise and vibration increase. Therefore, the unit rotors A and B that do not generate unbalanced electromagnetic force are brought close to each other so that the adjacent rotors have the same polarity. Therefore, since the present invention has two coils, if the number of turns is halved, the torque is the same as that of the conventional 8-main pole machine, which is half of the 4-main pole machine, and the structure is very simple. Torque is obtained and no unbalanced electromagnetic force is generated.

In the case of the two-winding pole 2 auxiliary main pole of the present application, the desired number of rotor teeth Nr is derived from the following equation with reference to FIG.

90 / Nr = (− / +) {(360/4) −360n / Nr} (8)

However, n is an integer of 1 or more.
The left side and the right side of the equation (8) represent the step angles of this configuration, and when this is arranged, the equation (9) is obtained.

Nr = 4n ± 1 (9)

_Nr is a desirable form of a two-phase, two-winding pole, two auxiliary main pole structure, and the X axis and Y axis in FIG. 1 are orthogonal. The stator magnetic poles (1) and (3) and (2) and (4) are at a mechanical angle of 180 °.
The step angle is, for example, n = 19 and Nr = 75, and in a two-phase machine, the step angle is (90 / Nr) degrees, so that a stator rotating electric machine having a 1.2 degree step angle is obtained. The example shown in FIG. 1 is a _N r = 25,3.6 ° step angle at n = 6.
Moreover, if it makes it symmetrical with Z axis | shaft, if it will be a back and front alternate lamination | stacking, the rolling thickness difference of the hoop material of a silicon steel plate can be absorbed. In the case of three phases, equation (10) is obtained by similar calculation.
Nr = 3n ± 1 (10)

  Since the rotating electrical machine according to the present invention is thin, has a high torque and is inexpensive, it can provide a low-cost and high-torque motor for use in a copying machine or printer as an OA device, and is expected to make a significant industrial contribution. The In addition, application to medical equipment, FA equipment, robots, amusement machines, and housing equipment is also highly expected.

Figure of the rotating electrical machine unit of the present invention Front view of FIG. Figure of the end ring of the present invention Illustration of another end ring of the present invention Completion drawing of the rotating electrical machine of the present invention Front view of FIG. Completion drawing of another rotating electrical machine of the present invention Front view of FIG. Prior art diagram Cross section of FIG. Illustration of another rotor applicable to the present invention

Explanation of symbols

1,: Stator teeth 2, 3
: End ring 4: Powder iron core,
5: Coil,
6: laminated iron core,
7: Bearing 12: Output shaft 25, 26, 27, 28, 31: Rotor 29, 30
: Permanent magnet 32
: Stator core

Claims (6)

A plurality of (m) laminates are formed by laminating magnetic plates, and each laminate is concentrically dispersed and arranged by connecting a part of each laminate in the axial direction with an annular connector. A motor unit A is configured by arranging a rotor so as to face the inner peripheral portion of each laminate through an air gap.
A motor unit in which a coil is wound around a plurality (m pieces) of salient pole portions projecting inwardly from an annular portion of an annular magnetic body including a polygon and having respective tip surfaces joined to the outer periphery of each laminate. B
The rotating electrical machine, wherein an axial length of the salient pole portion of the motor unit B is set to be shorter than an axial length of the laminated body of the motor units A. Each of the laminates has a plurality of magnetic teeth in a portion facing the rotor,
As the rotor, multiple N evenly on the outer periphery _r A hybrid rotor is used, which is composed of a pair of magnetic disks having magnetic teeth and sandwiched between permanent magnets magnetized in the axial direction in a state where they are shifted from each other by half the tooth pitch. The rotating electrical machine according to claim 1, wherein: The two hybrid rotors are provided on a common shaft, the permanent magnets of the respective rotors are opposite to each other in the axial direction, and the positions of the magnetic teeth of the magnetic disks facing each other are the same. The rotating electrical machine according to claim 2, wherein: Each of the laminates has a plurality of magnetic teeth in a portion facing the rotor,
The rotor is equally N on the outer periphery _r 2. The rotating electrical machine according to claim 1, wherein the rotating electric machine is a cylindrical permanent magnet rotor having a number of pole pairs. The stator annular magnetic body in the motor unit B is composed of a dust magnetic body having an axial height jaw portion that absorbs a coil end of a coil wound around a salient pole portion. The rotating electrical machine according to any one of claims 1 to 4. The rotation according to any one of claims 1 to 4, wherein the stator annular magnetic body in the motor unit B is constituted by a laminated steel plate, and the axial thickness of the annular portion is the same as the salient pole portion thickness. Electric.

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