WO2007034868A1 - Permanent magnet dynamo-electric machine - Google Patents

Abstract

[PROBLEMS] To obtain an inexpensive, low-vibration, high-torque dynamo-electric machine having a simple winding such as an HB type stepping motor, including a four winding structure having a two-phase, four-main pole inductor, where a rotor consists of two sets of HB rotor with their same polarities arranged adjacently, and a low grade permanent magnet of 0.5 [T] or below is employed. [MEANS FOR SOLVING PROBLEMS] A permanent magnet is clamped by two rotors, each having Nr teeth provided rotatably through a plurality of inductors and an air gap at the distal ends of four main poles having two-phase windings provided radially from a substantially annular magnetic body, while being shifted from each other by one half of the teeth pitch to produce a unit rotor. A rotor formed by two sets of the unit rotor arranged adjacently, and the permanent magnet clamped with its teeth position aligned and with the same polarity having residual flux density of 0.5 [T] or less are used to produce a permanent magnet dynamo-electric machine.

Description

 Specification

 Permanent magnet type rotating electric machine

 Technical field

 The present invention relates to a permanent magnet type rotary electric machine such as a permanent magnet type stepping motor, and more particularly to improvement of a permanent magnet type rotary electric machine with low cost, small size and high torque.

 Background art

 [0002] A small size, high torque and low vibration are required for a rotating electric machine such as a stepping motor used for OA equipment and the like.

 In order to solve this problem, one of the inventors of the present invention has already filed patent applications disclosed in the following Patent Documents 1 and 2, but this application is an improvement technique of these prior patents. .

 Here, a conventional permanent magnet type rotary electric machine will be described using FIG. 4 and FIG.

 FIG. 4 is a front view showing a partial configuration of a conventional permanent magnet rotating electric machine.

 FIG. 5 is a longitudinal side view showing a basic configuration of a conventional permanent magnet rotating electric machine.

In the conventional two-phase permanent magnet type rotary electric machine 100 shown in FIGS. 4 and 5, the stator 101 has eight main poles 111 to 118 with a plurality of inductors, and the rotor 102 is It is a hybrid rotor comprising a pair of rotor elements 121, 122 provided with a plurality of teeth for sandwiching a disk-like permanent magnet 151.

 In FIG. 5, reference numeral 104 denotes an axis, and reference numeral 103 denotes a coil.

Patent Document 1: Japanese Patent Application No. 2001-317708

 Patent Document 2: U.S. Pat. No. 6,781,260 B2

 Disclosure of the invention

 Problem that invention tries to solve

[0006] By the way, the conventional permanent magnet type rotating electric machine has the following problems.

 (1) In the case of a rotating electrical machine which is thin in the axial direction, the magnet is too strong in the rare earth magnet and there is a problem that the torque decreases due to the force.

(2) In the thin axial rotating electric machine, it is necessary to make the magnet thinner, but if it is made thinner, the magnet It was broken and the productivity deteriorated.

 (3) If two rare earth magnets are used, the proportion of the cost of the magnets is large as an inexpensive motor, and it is necessary to make the magnets inexpensive.

An object of the present invention is to solve the above-mentioned problems (problems) and to provide an inexpensive, small-sized, high-torque permanent magnet type rotary electric machine.

 Means to solve the problem

The permanent magnet type rotating electric machine of the present invention is configured as follows.

 "Measure 1"

 The stator according to claim 1 has a plurality of inductors at the tips of four main poles having a two-phase winding provided radially from a substantially annular magnetic body, with an air gap interposed therebetween. A rotor with two sets of unit rotors sandwiched by two permanent magnets with Nr teeth that are rotatably installed and offset by 1Z2 of the tooth pitch with each other is adjacent to each other. A permanent magnet-type electric rotating machine in which the permanent magnet to be held has the same position and the same polarity as each other and the residual magnetic flux density is not more than 0.5 [T].

[0009] "Means 2"

 A permanent magnet type rotating electric machine according to claim 2, wherein the permanent magnet is a bonded magnet having a residual magnetic flux density of not more than 0.5 [Τ].

[0010] "means 3"

 According to a third aspect of the present invention, in the first aspect, the tooth pitch of the inductor provided at the tip of the four main poles in the stator is set to a degree of 7.2 (1-lZmNs), and Nr = 50. Permanent magnet type rotating electrical machine using

 Where m is the high-order harmonic number of the magnetic flux distribution of the air gap.

[0011] "means 4"

 A permanent magnet type rotary electric machine according to claim 4, wherein Nr = 4 n ± 1 in claim 1.

 However, n is an integer of 1 or more.

[0012] "means 5"

According to a fifth aspect of the present invention, in the first aspect, the stator outer periphery is substantially square and four main poles are provided. When the winding pole of each of the four sides of the square is disposed at right angles at the center of the square and the number Ns of teeth of the inductor provided at the tip is Nr = 50, the center of the inductor tooth portion and the center of the four winding pole A permanent magnet-type electric rotating machine that uses an angle of α degrees, (1.8 degrees) degrees, (3.6 degrees) degrees, and (3.6 degrees) degrees.

 However, α is more than 0 degrees and less than 1.8 degrees.

 Effect of the invention

 The permanent magnet type rotary electric machine of the present invention has the following excellent effects because it is configured as described above.

 (1) A magnet of optimum magnetic force can provide a permanent magnet type rotating electric machine excellent in cost performance.

 (2) With thin magnets used in thin rotary electric machines, bond magnets can be used to provide inexpensive rotary electric machines without cracking.

 (3) A compact, high-torque electric rotating machine with simple windings and no unbalanced electromagnetic force can be provided at low cost.

 BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, Example 1 and Example 2 of the permanent magnet type rotary electric machine of the present invention will be sequentially described with reference to FIG. 4 and FIG. 5 using FIG. 1 to FIG.

Example 1

 First, a first embodiment of a permanent magnet type rotary electric machine according to the present invention will be described with reference to FIGS. 4 and 5 using FIGS. 1 to 3.

 FIG. 1 is a front view for illustrating a partial configuration of a permanent magnet type rotary electric machine according to a first embodiment.

 FIG. 2 is a longitudinal side view for explaining the basic configuration of the permanent magnet type rotary electric machine of the first embodiment.

 Hereinafter, the basic configuration of the permanent magnet type rotary electric machine 10 of the first embodiment will be described with reference to FIG. 1 and FIG.

FIG. 1 is a block diagram of a stator core 1 and a rotor 2 of a two-phase four main pole permanent magnet type rotating electric machine 10 according to the present invention as viewed in the axial direction. In FIG. 1, 1 is a stator core (hereinafter sometimes referred to simply as "stator"), and 2 is a rotor.

 [0017] The two main poles 11 and 13 or the main poles 12 and 14 facing each other at 180 degrees of the stator core 1 are configured to be in phase and excited with phase currents of different polarities. .

 At this time, for example, if the N pole rotor 2 faces the main pole 11, the rotor 2 does not face the main pole 13 (180 ° electrical angle in the peaks and valleys) and the main pole 12 The main pole 14 and the rotor teeth are in a phase relationship of 90 degrees as shown.

 And, since the south pole rotor 2 not shown in FIG. 1 is disposed so as to deviate from the north pole rotor by 1Z2 of the rotor tooth pitch, that is, the electrical angle 180 degrees, Become.

 Further, FIG. 2 is a longitudinal cross-sectional view of the permanent magnet type rotary electric machine 10 of the present invention including the shaft 4, but in the same figure, 21 and 22 are made of magnetic material, and Nr teeth are provided on the outer periphery. The rotor elements, each having a tooth pitch of 1Z2 offset from each other, sandwiching 51 disc-shaped permanent magnets magnetized in the direction of the axis 4 with one pair of rotor pairs, so-called hybrid Construct a rotor.

 Then, coaxially connect and arrange another pair of identical rotor sets.

 At this time, the adjacent rotor elements 22 and 21 magnetize the two permanent magnets 51 so as to have the same polarity.

 In addition, it is desirable that the adjacent rotor elements 22 and 21 be integrally formed of laminated steel plates in the same tooth position and in integral force.

 In FIG. 2, 3 is a core and 4 is an axis.

 Further, although the front and rear brackets, ball bearings, etc. are illustrated, the description is omitted.

The reason for providing the two sets of rotors 2 is to cancel the radial unbalanced electromagnetic force generated by the combination of the four main pole stators 1 and the usual hybrid rotor, for example, N pole The rotor element 21 (left side in Fig. 2) and the rotor element 22 of N pole (right side in Fig. 2) are pulled upward.

 The rotor element 22 of the S pole and the rotor element 21 (the center of FIG. 2) are both drawn downward.

Therefore, the unbalanced electromagnetic force in the radial direction is canceled without generating a couple. The detailed principle is described in detail in the above-mentioned Patent Documents 1 and 2 invented by one of the inventors of the present application using formulas, so that the detailed description is omitted here.

 The configurations of FIGS. 1 and 2 of the present application are two-phase, limited type stepping motors. The configuration of the present application can be applied to a brushless motor or a synchronous motor.

Next, comparison of torques T 4 and Τ 8 of the respective rotating electrical machines when the same rotor is combined with the two-phase four main pole stator 1 of the structure of the present invention and the conventional eight main pole stators explain.

 First, the torque T1 for the N1 phase is expressed by equation (1).

Tl = Nnrim (1) where Nr is the number of rotor teeth, N is the number of coil turns, i is the current, and ιπι is the flux linkage with the coil of the permanent magnet flux of the rotor force.

 In both cases, the same wire diameter and the same total number Nt are used.

Also, it is assumed that the total amount of magnetic flux coming out of the rotor is equal to, for example, 48 (eight main poles 8 × 6 = 48, four main poles 4 × 12 = 48) of the teeth of both stators. In this case, the magnetic resistance difference between the two stator cores can be ignored and the same value of can be approximated to, so that each of the 8 main pole machines and 4 main pole machines has a power of 1 main pole and a magnetic flux of Ν8, Ν4, Φ The following equations (2) to (5) hold as 8 and 44.

8 8 = ί / 8 (2)

4 4 = ί / 4 (3)

N8 = Nt / 8 (4)

N2 = Nt / 4 (5)

As described above, according to equations (1) to (5), the torques T8 and T4 of the eight main poles and the four main poles of each rotating electric machine are as follows. T8 = 2 * 4 (Nt / 8) Nri (t t / 8)

 = Nt Nri t / 8 (6)

T2 = 2 * 2 (Nt / 4) Nri (t t / 4)

 = Nt Nri t / 4 (7)

According to Eqs. (6) and (7), the 4 main pole machine can deliver about twice as much torque as the motor of the conventional 8 main pole machine.

 Incidentally, the desirable number Nr of rotor teeth in the case of the rotating electrical machine of the four main poles is derived from the following equation (8).

90 / Nr = (− / +) {(360/4) −360n / Nr} (8) However, n is an integer of 1 or more.

 Here, the symbol (-Z +) is determined by the subtraction of the first term and the second term on the right side, and the magnitude of the value of the first term and the second term becomes-or + is there.

Since the left side and the right side of the equation (8) represent the step angles of this configuration, the equation (9) can be obtained by arranging the step angles.

Nr = 4 n ± 1 (9) The number of rotor teeth Nr is a desirable form of a rotating electrical machine with a two-phase four-principal symmetrical structure. For example, n = 19 and Nr = 75, and in a two-phase rotating electrical machine, (90 ZNr) degrees is the step angle, so that a symmetrical stator rotating electrical machine with a 1.2 degree step angle can be obtained.

In this case, since the stator is 90 ° symmetrical, 90 ° rotation can be carried out during stacking. If rotational stacking can be performed, the deviation of the stack thickness can be eliminated and the magnetic directionality of the silicon steel sheet can be canceled, resulting in good motor characteristics. Next, as shown in FIG. 2, since two permanent magnets 51 are used, it is possible to obtain high torque even with a low grade magnet. Shown in comparison with the case of individual use (see Fig. 5).

 The permanent magnet 151 used in the conventional two-phase eight main pole type rotary electric machine 100 is a rare earth magnet and a neodymium magnet having a residual magnetic flux density Br of 1.3 [T].

[0027] On the other hand, in the case of the present application, since the two-phase four main pole has two magnets, the magnetic flux density Br of the magnet is obtained by the following equation (10).

Br = l. 3 [T] X (1/2) X (3/2) X (4/8)

 = 0.4875 [Τ] (10)

In equation (10), the coefficient (1Z2) is compared with a conventional rotor of an outer rotor area excited by a single magnet in combination with a conventional eight main pole of the same size. Since the magnetic flux generated from the permanent magnet 51 may be half because it is approximately 1Z2, if the area of the magnet is the same, then the magnetic flux density Br of the magnet is half and it is used for the reason that

 Further, in the equation (10), the coefficient (3Z2) is such that the permeance of the stator core 1 is approximately doubled simply because the magnetic path length of the permanent magnet 51 is reduced by half. The total permeance approximates to about 3Z2 times in consideration of the decrease in magnetic flux density in the path.

Furthermore, in the equation (10), the coefficient (4Z8) means the ratio of the number of main poles, (4 main poles Z8 main pole), and the torque T4, Τ8 is the above-mentioned equations (6) and (7) It is because it is in inverse proportion to the number of main poles from the relation of a formula.

 With a magnet of the value of magnetic flux density Br in this equation (10), torque equivalent to that of an 8-main-pole motor using a neodymium magnet with a magnetic flux density Br of 1.3 [T] (Tesla) can be obtained. The result of equation (10) almost agrees with the result of magnetic field analysis by the computer.

The value of the magnetic flux density Br corresponds to a ferrite magnet.

A ferrite magnet has a magnetic flux density Br of 0.5 [T] and a coercivity of about Hcj = 275 KAZm, and its demagnetization curve has a straight line in the second quadrant of the coordinate where the coercivity is taken vertically. The The operating point is the point at which the demagnetization curve intersects with the straight line passing through the origin with the permeance coefficient of the permanent magnet assembled in the magnetic path as its gradient. The operating point magnetic flux density is approximately the magnetic flux density Br of the permanent magnet. (6) is approximately established because it is proportional to.

Ferrite magnets are extremely inexpensive compared to rare earth magnets, and two magnets are cheaper than neodymium magnets.

 That is, a practical torque can be obtained with a magnet having a magnetic flux density of 0.5 [T] or less.

 If it is a magnet of 0.5 [T] or less, not only a dry or wet sintered ferrite magnet but also a bonded (plastic) magnet using a resin as a binder may be used.

 In sintered ferrite magnets, for example, the outer diameter is 25 mm and the thickness is about 2 mm for mass production, and if thinner than that, cracking defects occur frequently.

 If this is used as a bond magnet, cracking and defects will be resolved.

[0033] By using a low-grade permanent magnet of 0.5 [T] or less while suppressing the unbalanced electromagnetic force with the two-phase four-winding stator and the above-described two-rotor rotor, the conventional expensive neodymium-fired is In contrast to motors of the same size that use magnets and rare earth magnets such as samarium cobalt magnets, the means to double the torque is a revolutionary new technology.

In the rotating electric machine 10 of the present application, since the radial direction attraction force is distributed and balanced by four rotors compared to the conventional two-piece configuration, the clearance due to the bearing etc. With regard to vibration and noise, the rotating electric machine 10 of the present application is advantageous over the conventional rotating electric machine 100.

, Low vibration, low noise.

On the other hand, in the rotary electric machine 100 of the conventional configuration of the rotor 102 incorporated in the stator 101 of two-phase and eight main poles of FIG. 4, as described above, the rotor 102 is a pair of so-called hybrid rotors. 121, 122.

 Since the stator 101 has eight main poles 111 to 118, the unbalanced electromagnetic force basically does not occur if it is accurately made.

 However, in this case, as compared with the present invention, since the radial attraction force is concentrated and balanced with two rotors 121 and 122, vibration due to clearance of bearings etc. is slightly deviated. It can be said that noise is easier to cause than the present invention.

Further, in FIG. 2 which is the rotating electric machine 10 of the present invention, a non-magnetism is generated between the adjacent rotor elements 22 and 21 In the case of opposite polarity by sandwiching the elastic spacer, the stator 1 and the rotor 2 can not face each other by this thickness, which is disadvantageous in terms of torque.

 Further, as described above, the torque of the rotary electric machine 100 according to the prior art shown in FIG.

Example 2

 Next, a second embodiment of the permanent magnet type rotary electric machine according to the present invention will be described with reference to FIG. FIG. 3 is a front view showing a partial configuration for explaining an embodiment 2 of the permanent magnet type rotary electric machine of the present invention.

 FIG. 3 shows a stator 30 used in Example 2 of the present application.

 By the way, a two-phase four-main-pole stepping motor can be used even if it does not follow the above-mentioned equation (9). For example, if the number of rotor teeth Nr = 50, then the step angle is 1.8 degrees. ) Does not meet the formula.

 In this case, the stator is not symmetrical.

 In this embodiment, the outer periphery of the stator 30 is substantially square, and the winding portions of the four main poles 31 to 34 (hereinafter referred to as the upper winding pole for convenience, the main poles of the inductor portion) When the number of teeth Ns of the inductor provided at the tip is Nr = 50, the center teeth of the number Ns of teeth of the inductor and 4 windings Angular force at the center line of the pole 0.9 degree force ^ place, 2. 7 degree is 2 places.

 The reason for making the shape of the stator 30 square is to secure a large winding space.

 The reason is that when the shape of the stator is circular, the winding space is smaller.

 Also, for example, the angle formed by the center teeth of the number Ns of teeth of the inductor and the center line of the 4-turn pole can be 0 degree at one place, but in that case, the other angle is 1.8 degrees. The reason is to set the angle to 3.6 degrees, etc., and to prevent it from increasing by 3.6 degrees against the maximum deviation of 2.7 degrees in Fig. 3.

Assuming that the number of rotor teeth Nr is 50 in the above-mentioned means 5 (see paragraph [0001]), the angle formed by the center tooth of the number Ns of teeth of the inductor and the center line of the four winding poles Force α degree, (1.8-α) degree, In the state of (3. 6-α) degrees, (3-6-a) degrees, if a = 0, then the above-mentioned maximum deflection angle of 3.6 degrees is obtained. The sex is bad.

In addition, when the stator inductor tooth pitch is narrowed by δ = (1.8 / Ns) degrees with respect to the rotor tooth pitch of 7.2 degrees, the magnetic flux distribution by the permanent magnet of the air gap that produces cogging torque The fourth harmonic component of can be canceled.

 That is, the tooth pitch may be {7.2-(1.8 ZNS)} degrees.

 If δ is generally indicated, the following equation is obtained. δ = 360 / mNsNr (11) where m is the mth harmonic component of the magnetic flux distribution of the permanent magnet in the air gap. In a two-phase machine, m = 4 and substituting Nr = 50 into equation (11) yields the above 1.8 ZNs.

 Further, the inductor tooth pitch γ degree of the stator is expressed by the following equation. γ = 7.2 (ll / mNs) (12) The stator tooth pitch γ degree of the stator 30 in FIG. 3 is 7.036 degrees, if m = 4 and Ns = ll are substituted in the equation (12). Become.

 As a result, a rotating electric machine with a minimal cogging torque can be obtained.

 Industrial applicability

Since the permanent magnet type rotating electrical machine of the present invention can produce high torque with an inexpensive magnet, it becomes an inexpensive, high torque, low vibration actuator of a copying machine or printer which is an OA apparatus, and a large industrial contribution is expected. Ru.

 In addition, applications to medical equipment, FA equipment, robots, play machines, and home equipment are also highly expected.

 Brief description of the drawings

FIG. 1 is a front view for describing a partial configuration of a permanent magnet type rotary electric machine of a first embodiment. FIG. 2 is a longitudinal side view for explaining the basic configuration of the permanent magnet type rotary electric machine of the first embodiment.

3) A front view showing a partial configuration for explaining a second embodiment of the permanent magnet type rotary electric machine of the present invention.

 FIG. 4 is a front view showing a partial configuration of a conventional permanent magnet rotating electric machine.

5) It is a longitudinal side view showing a basic configuration of a conventional permanent magnet rotating electric machine.

Explanation of sign

 1: Stator core (stator)

 2: Rotor

 3: Coil

 4: Rotation axis

 21, 22: Rotor element

 51: Permanent magnet

Claims

The scope of the claims  [1] The stator has a plurality of Ns inductors at the tip of each of four main poles with two-phase windings provided radially from a substantially annular magnetic body, and is rotatable via an air gap. Two rotors with Nr teeth and two permanent magnets sandwiched between two permanent magnets and offset each other by 1Z2 tooth pitch are provided, and the adjacent rotors have tooth positions A permanent magnet-type electric rotating machine characterized in that the residual magnetic flux density of the held permanent magnet is not more than 0.5 [T] with the same and the same polarity.  [2] The permanent magnet type rotating electrical machine according to claim 1, wherein the permanent magnet is a bonded magnet having a residual magnetic flux density of not more than 0.5 [T].  [3] In claim 1, the tooth pitch of the inductor provided at the tips of the four main poles of the stator is 7.2.  The permanent magnet type rotating electric machine according to claim 1, wherein Nr is 50 (1−1 ZmNs).  Where m is the high-order harmonic number of the magnetic flux distribution of the air gap. [4] The permanent-magnet type electric rotating machine according to claim 1, wherein Nr = 4n ± 1.  However, n is an integer of 1 or more. [5] In claim 1, the outer periphery of the stator is substantially square, and the winding poles of the four main poles are disposed at right angles at the centers of the four sides of the square, and the number of teeth of the inductor provided at the tip is When Nr = 50 as Ns, the angular force α degrees, (1. 8 α) degrees, (3. 6-α) degrees, (3. The permanent magnet type rotary electric machine according to claim 1, characterized in that 6-alpha) degrees.  However, α is more than 0 degrees and less than 1.8 degrees.