JP2008187846A - Permanent magnet type 2-phase rotary electric machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact, simple and inexpensive permanent magnet type 2-phase rotary electric machine containing a stepping motor by employing two winding poles. <P>SOLUTION: This permanent magnet type 2-phase rotary electric machine includes a plurality of inductors on each end of a stator main pole, which is provided in such a manner so as to project inward from a roughly rectangular magnet substance, having two 2-phase type winding poles and two auxiliary poles. In the 1-phase of main pole, one winding pole is separated at a mechanical angle of almost 180° from one auxiliary pole and respective plurality of small teeth positions are displaced at an electrical angle of almost 180° from each other in the winding pole and the auxiliary pole. Two unit rotors A and B having a plurality (Nr) of teeth rotatably mounted through air gap, which sandwich two axially magnetized permanent magnets displaced by half pitch each other, are installed on the common rotating shaft to rotatably ensure air gap for assembly. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rotating electrical machine such as a stepping motor in which a stator composed of a winding pole and an auxiliary pole not having a winding and a hybrid permanent magnet rotor in which two permanent magnets are repelled and magnetized in opposite directions. About.

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. Four stator main poles (1 and 2) (Fig. 5 of the present application) are used as two-phase windings to eliminate unbalanced electromagnetic force and achieve higher torque than a two-phase eight-main motor. However, the winding inductance is larger than that of the 2-phase 8-main pole motor, and high torque is realized in the low-speed rotation range. For example, in the rotation range of about 1500 rpm or more when the step angle with 50 rotor teeth is 1.8 degrees, 6. Since current does not flow from the conventional two-phase 8-main pole motor shown in FIG.
2) Although the two-phase winding motor having four stator main poles in Patent Documents 1 and 2 is simpler and cheaper than the two-phase eight main pole motor, there is a demand for a cheaper motor in the market. is there.
3) In the market, there is a strong demand for smaller and cheaper motors that have the same torque as the two-phase 8-main pole motors.

The present invention is realized by the following means.
"Means 1"
Plural inductors at each end of the stator main pole, which consists of two winding poles and two auxiliary poles in a two-phase system, protruding from a polygon including a quadrilateral or a substantially annular magnetic body. The main pole for one phase is a position where one wound pole and one auxiliary pole are separated by approximately 180 ° in mechanical angle, and each of the plurality of small tooth positions is separated by 180 ° in electrical angle from each other. Two permanent magnets magnetized in the axial direction with two rotors each having a plurality of Nr teeth provided rotatably through an air gap are sandwiched by shifting each other by a half pitch of the tooth pitch. Two sets of unit rotors, unit rotors A and B, are provided on a common rotating shaft, and adjacent or adjacent rotors of unit rotors A and B have the same tooth position and are magnetized to the same polarity. The unit rotor A side bracket and the unit rotor B side bracket can be rotated on both sides of the stator. Ri permanent magnet type rotating electric machine according to means to be assembled to secure the air gap.
"Means 2"
A permanent magnet type rotating electrical machine in which the number of rotor teeth in means 1 is Nr = 4n ± 1.
"Means 3"
A permanent magnet type rotating electrical machine in which the rotor in the means 1 is a rotor including a cylindrical permanent magnet in which N poles and S poles are alternately arranged in the circumferential direction of the rotor.
"Means 4"
4. A permanent magnet type rotating electrical machine according to claim 3, wherein the number of pole pairs of the rotor is 4n ± 1.
"Means 5"
A permanent magnet type rotating electrical machine that realizes a reduction in size by means that the motor output shaft position is different from the center of the annular stator in means 1 to 4.
"Means 6"
A permanent magnet type rotating electrical machine that uses a permanent magnet as a ferrite magnet in the means 1 and 2.

1) Since there are four stators including the winding and auxiliary poles, the inductance is half that of the four-winding type, and the same winding inductance and torque as in the conventional eight-winding type can be obtained. In addition, the torque at the low speed is half that of the conventional four main poles (winding poles), but at high speeds (at about 1500 rpm), the inductance is small, which is better.
2) The motor size can be reduced to about 83% with the same output torque compared to the conventional 8-winding pole motor with the same rotor diameter.
3) With a thin motor HB machine, it is possible to use an inexpensive magnet with low magnetic energy, such as a bond magnet or a ferrite magnet, and a permanent magnet type rotating electrical machine with excellent cost performance can be provided.
4) Because of the two winding poles, the winding is simple, and a small rotor with high torque and no unbalanced electromagnetic force can be provided at low cost by a special rotor.

  This will be described below with reference to the drawings.

FIG. 1 is a configuration diagram seen from the axial direction of a rotating electrical machine by a combination of a two-phase two-winding pole, which is a reduced-main-pole structure stator of the present invention, and a two auxiliary pole stator and a special HB type rotor. However, the illustration of the shaft is omitted. Reference numeral 1 denotes a stator core, which can be a polygon or a circle including a substantially quadrilateral, and 2 is a diagram of a hybrid (hereinafter abbreviated as HB) rotor. 3 is a winding. In FIG. 1, the intersection of the Y1-Y2 axis and the X1-X2 axis is the output shaft position. If the outer shape is a square in FIG. 1 from the position of the output shaft, a> b for the winding 3. If the number of rotor teeth Nr = 4n ± 1 is selected with respect to the Z1-Z2 axis, line symmetry is obtained. FIG. 2 is a cross-sectional view including the axis of FIG.
The stator is a two-phase, two-winding pole with two inductors at each end of the two auxiliary pole main poles. The main pole for one phase consists of one winding pole and one auxiliary pole. Each position of the plurality of small teeth is positioned 180 ° apart from each other by an electrical angle of 180 ° as a position separated by an angle of about 180 °, and a plurality of Nr pieces (25 pieces in FIG. 1) are rotatably provided through an air gap. The permanent magnets 51 magnetized in the axial direction by two rotors 21 and 22 having teeth of which teeth are evenly arranged but only the portion facing the stator pole inductor magnetic teeth are shown in the tooth pitch. Are provided on the common rotating shaft 4 as two sets (23, 51, 24) of unit rotators, which are sandwiched with a ½ pitch shift, and unit rotators A and B. Rotors 22 and 23 adjacent to or adjacent to B have the same tooth position and are magnetized to the same polarity so that they can rotate freely. Is assembled by securing the air gap from the stator sides in rotor unit A side of the bracket and the rotor unit B side of the bracket. It is desirable that the stators (1) and (2) are separated by 180 ° in mechanical angle. However, the number of teeth of the rotor will be described later, but if n is an integer equal to or greater than 1, it is close to 180 degrees. Design to value.
Two sets of unit rotors may be brought into close contact with each other. However, if 22 and 23 are brought close to each other and a thin nonmagnetic plate or conductive plate is inserted between them, magnetization becomes easy.
At this time, for example, referring to FIG. 1 and FIG. 2, if only one phase is excited and the N-pole rotor 21 is opposed to the wound main pole (1) excited by the one-phase S pole, one phase The auxiliary pole (2) of the minute is magnetized to the N pole and has a phase relationship that is not opposed to the rotor 21 of the N pole (opposed by teeth and grooves and 180 degrees in electrical angle). On the other hand, the auxiliary pole (3) for one phase is opposed to the S pole 22 of the rotor. Then, the rotor magnetic flux of the rotor A is linked to the exciting one-phase winding coil 3. At this time, the stator main pole teeth and rotor teeth of two phases which are not excited have a phase relationship of 90 degrees in electrical angle. The tooth positional relationship between these rotors and the stator is as shown in FIG. Further, the same magnetic circuit is formed in the axial direction facing the rotor B in the same manner as the one-phase stator, so that the magnetic circuit can be shortened to half that of the single rotor.
1 and 2, since the present invention has only two coils and the rotor shaft is not at the center of the motor but at a different center, the size can be reduced accordingly.

4 and 3 that the unbalanced electromagnetic force is canceled even in the configuration of the present invention.
In FIG. 3, the radial suction forces F <b> 1 and F <b> 4 of FIG. 4 are generated by the stator (1) and the rotors 21 and 23. Similarly, F2 and F3 are generated in the rotors 22 and 23 at the auxiliary pole (3). These radial suction forces cancel each other. In FIG. 4, the front and rear brackets are 6 and 7, respectively, and the moment force M with the fulcrum at the center of the bearing 8 is also cancelled.
That is, M = L ₁ F ₁ + (L ₁ + L ₂ + L ₃ + L ₄ ) F ₄ − (L ₁ + L ₂ ) F ₂ − (L ₁ + L ₂ + L ₃ ) F ₃
(1)
Further, the following equations (2) and (3) are established.
F ₁ = F ₂ = F ₃ = F ₄ (2)
L ₂ = L ₄ (3)
Substituting (2) and (3) into the right side of equation (1), M = 0 (4)
The moment force M is canceled.
The point is that F ₂ and F ₃ by the auxiliary pole have the same value as the winding poles F ₁ and F ₄ and the leakage magnetic flux is ignored.
5, 6 and 7 are diagrams of the prior art. FIG. 5 is a diagram in which the winding of Patent Document 1 is omitted, and the rotor is the same as FIG. As described above, since there are four windings compared to the present application and the 8-winding pole type, the inductance is about twice as large, and the torque is about twice as high as that of a normal 8-winding pole as described later. There was a problem that the torque became small at high speed rotation. If this is applied as in the present application, the torque at the low speed is the same as that of the half 8-winding pole and the number of coils is two, and the inductance is also halved. FIG. 6 is a view showing a two-phase HB type rotating electric machine having a stator 8 and a rotor 31 of a normal 8-winding pole, in which windings are not shown, and FIG. 7 is a cross-sectional view including a shaft. In FIG. 7, the above-described HB rotator uses the rotors 31 and 32 that are arranged at tooth positions shifted from each other by 1/2 of the tooth pitch and the unit rotor of the permanent magnet 33 magnetized in the axial direction. . Reference numerals 15 and 16 denote front and rear brackets.

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 (5)
The torque for one phase is expressed by equation (5). 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 (6)
Φ4 = Φt / 4 (7)
N8 = Nt / 8 (8)
N2 = Nt / 4 (9)

From the formulas (5) to (9), the torques of the 8 main pole 4 main pole machine, T8 and T4 are as follows.

T8 = 2 * 4 (Nt / 8) Nri (Φt / 8)
= NtN _r iΦ _T / 8 (10)
T2 = 2 * 2 (Nt / 4) Nri (Φt / 4)
= NtNriΦt / 4 (11)

From (10) and (11), the 4-main pole machine can output about twice as much torque as the motor of the conventional 8-main pole machine. However, in the case of a normal unit rotor, an 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 and the same as the 8-wind type. 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) −360 n / Nr} (12)

However, n is an integer of 1 or more.
The left side and the right side of the equation (12) represent the step angles of this configuration, and when this is arranged, the equation (9) is obtained.

Nr = 4n ± 1 (13)

_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.

Since two permanent magnets are used in Fig. 2, the fact that high torque can be obtained even with low grade magnets is compared with the case of using a conventional two-phase 8-main pole type magnet (configuration in Figs. 6 and 7). Show. The conventional permanent magnet used in the two-phase 8-main pole type is a rare earth magnet, a neodymium magnet, and a residual magnetic flux density Br of 1.3 [T]. On the other hand, since there are two magnets in the case of the present application, the Br of the magnet is obtained by the following equation.

Br = 1.3 [T] x (1/2) (3/2) (4/8) = 0.4875 [T] (14)

In equation (14), (1/2) is approximately ½ the outer peripheral area of the rotor excited by one magnet compared to a conventional HB rotor combined with a conventional eight main pole of the same size. Therefore, the magnetic flux generated from the permanent magnet may be halved, so if the magnet area is the same, the magnetic flux density of the magnet may be halved. (3/2) is the iron core because the magnetic path length of the permanent magnet is halved. The permeance at the portion is simply about twice, but the permeance is approximated to about 3/2 times in total in consideration of the decrease in the air gap and the magnetic flux density of the magnetic path. (4/8) means (4 main poles / 8 main poles), and the torque is due to being inversely proportional to the number of main poles based on the relationship between the above-mentioned formulas (10) and (11).
A torque equivalent to that of an 8-main pole motor using a Ne value magnet having a Br value of 1.3 [T] (Tesla) with a magnet having a value of Br in the equation (14) can be obtained. The result of the equation (14) almost coincides with the magnetic field analysis result in the computer.
The value of Br corresponds to a ferrite magnet. The ferrite magnet has a Br of 0.5 [T] and a holding force Hcj of about 275 KA / m, and its demagnetization curve becomes a straight line in the second quadrant of the coordinates where the magnetic flux density is perpendicular and the holding force is taken horizontally, The operating point is the intersection of the straight line passing through the origin with the permeance coefficient of the assembled permanent magnet as the gradient and the demagnetizing curve. The operating point magnetic flux density is approximately proportional to Br of the permanent magnet ( 14) is established. Ferrite magnets are extremely cheaper than rare earth magnets, and even if two are used, they are cheaper than neodymium magnets. That is, sufficient practical torque can be obtained with a magnet of 0.5 [T] or less. If it is a magnet of 0.5 [T] or less, it is not limited to a dry or wet sintered ferrite magnet, but may be a bond (plastic) magnet using a resin as a binder. In sintered ferrite magnets, for example, an outer diameter of 25 mm and a thickness of about 2 mm are the limit for mass production, and if it is thinner than that, crack defects frequently occur. If this is used as a bond magnet, the crack defect is solved.
By adopting a low-grade permanent magnet of 0.5 [T] or less while suppressing unbalanced electromagnetic force with the two-phase four-winding pole stator and the above-described two-line rotor, a conventional expensive neodymium sintered magnet Torque can be increased or reduced by the same size as the same size motors using rare earth magnets such as samarium cobalt magnets.

The description of the present invention so far has been made with the configuration of two sets of HB type rotors. On the other hand, for example, the rotor shown in FIG. 1 may be replaced with the rotor shown in FIG. 8 which is a cylindrical magnet in which the north and south poles of the rotor are alternately magnetized in the circumferential direction without changing the stator.
That is, in the case of FIG. 1, the logarithm of NS may be 25. In this case, the unbalanced electromagnetic force is canceled in the same manner because 21 and 24 correspond to the N pole of the cylindrical magnet and 22 and 23 correspond to the S pole of the cylindrical magnet in FIG. In the case of Nr pole pair number cylindrical magnets, Nr = 4n ± 1 is similarly established. n is an integer of 1 or more.

  Since the rotating electrical machine according to the present invention can produce a torque equivalent to that of the conventional two-phase 8-winding type with an inexpensive structure and an inexpensive magnet, it is possible to provide an inexpensive and high-torque motor for use in a copying machine or printer as an OA device. This is possible, and since the air gap can be increased, it becomes an actuator with low vibration and is expected to make a significant industrial contribution. In addition, application to medical equipment, FA equipment, robots, amusement machines, and housing equipment is also highly expected.

Diagram of the rotating electrical machine of the present invention Side sectional view of FIG. Figure of tooth position of the present invention Diagram of radial suction force of the present invention Figure of conventional rotating electrical machine Illustration of another conventional rotating electrical machine Side sectional view of FIG. Another rotor combined with the stator of the present invention

Explanation of symbols

1, 30: Stator 2, 21, 22, 23, 24, 31, 32: Rotor 3 ,: Winding,
4,: Output shaft 51, 33: Permanent magnet,
6, 15: Front bracket,
7, 16: Rear bracket 8: Bearing

Claims (6)

Plural inductors at each end of the stator main pole, which consists of two winding poles and two auxiliary poles in a two-phase system, protruding from a polygon including a quadrilateral or a substantially annular magnetic body. The main pole for one phase is a position where one wound pole and one auxiliary pole are separated by approximately 180 ° in mechanical angle, and each of the plurality of small tooth positions is separated by 180 ° in electrical angle from each other. The permanent magnets magnetized in the axial direction with two rotors having a plurality of _Nr teeth provided rotatably through an air gap are shifted from each other by ½ pitch of the tooth pitch. Two sets of sandwiched unit rotors are provided on a common rotating shaft, and the adjacent or adjacent rotors of the two sets of unit rotors have the same tooth position and are magnetized to the same polarity so that they can rotate freely. A permanent magnet type rotating electrical machine that is assembled with a gap secured.   The permanent magnet type rotating electrical machine according to claim 1, wherein the number of rotor teeth is Nr = 4n ± 1.   The permanent magnet type rotating electric machine according to claim 1, wherein the rotor is a rotor including a cylindrical permanent magnet in which N poles and S poles are alternately arranged in a circumferential direction of the rotor.   4. The permanent magnet type rotating electric machine according to claim 3, wherein the number of pole pairs of the rotor is 4n ± 1.   5. The permanent magnet type rotating electrical machine according to claim 1, wherein the motor output shaft position is different from the center of the annular stator.   3. A permanent magnet type rotating electric machine according to claim 1, wherein the permanent magnet is a ferrite magnet.

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