JPH0681469B2 - Electric motor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor including a field part having a field magnetic pole and an armature core having a winding groove.

Configuration of conventional example and its problems An electric motor in which a winding groove is provided in an armature core to accommodate a multi-phase winding, the magnetic flux of the field part is formed in the teeth formed between the winding grooves. Has the advantage that the output is large. Therefore, industrial robots and
Widely used as a driving power source for NC equipment. However, in such an electric motor, cogging torque is generated by the interaction between the magnetic poles of the field magnet and the winding grooves of the armature core. Hereinafter, this will be described with reference to the drawings, taking a brushless DC motor as an example.

FIG. 1 is a main part configuration diagram showing a structure of a conventional electric motor. An annular magnet 3 is attached to the outer circumference of a ferromagnetic rotor 2 attached to the rotating shaft 1. The magnet 3 is magnetized with four magnetic poles at equal angular intervals to form a field portion. An armature core 4 is arranged with a predetermined gap from the magnet 3 of the field unit. One of the magnet 3 and the armature core 4 is rotatably supported with respect to the other (in the present example, the armature core 4
In contrast, the magnet 3 is designed to rotate). The armature core 4 is provided with 24 winding grooves 5 at equal angular intervals, 24 teeth 6 are formed between the winding grooves, and three-phase windings A1 to A4 are provided. , B1 to B4 and C1 to C4 are wound and wound. The windings A1, A2, A3, A4 are wound so as to surround five teeth, and the winding A2 is placed in the winding groove next to both winding grooves in which the winding A1 is housed. One end of A4 is stored. Similarly, the winding groove next to both winding grooves containing winding A2 contains one end of windings A1 and A3, respectively, and both winding grooves containing winding A3. One end of each winding A2 and A4 is housed in the winding groove next to
One end of each of the windings A1 and A3 is housed in each of the winding grooves next to both of the winding grooves in which is stored. Winding B1 of the other phase
The same applies to ~ B4 and C1 to C4. Hereinafter, A1 to A4 are collectively referred to as an A phase winding group, B1 to B4 are referred to as a B phase winding group,
C1 to C4 are a group of C-phase windings. The magnetic flux generated by the magnet 3 of the field part flows into or out of each tooth of the armature core 4,
It is linked to the B and C phase winding groups. There is an electrical phase difference of 120 degrees between the A, B and C phase winding groups. Where 1 of electrical angle
80 degrees corresponds to one magnetic pole pitch of 360 ° / P in the magnetic field portion (P is the number of magnetic poles in the magnetic field portion) (in this example, P = 4, so mechanical angle
90 degrees is one magnetic pole pitch and corresponds to an electrical angle of 180 degrees).

FIG. 2 shows a configuration diagram of the drive circuit. Windings A1 to A4 in Fig. 1
Are connected in series in consideration of each winding direction to form an A-phase winding group. Similarly, windings B1 to B4 are connected in series in consideration of each winding direction to form a B-phase winding group, and windings C1 to C4
C4 is connected in series in consideration of each winding direction to form a C-phase winding group. The three-phase winding group is star-connected, and its terminals are connected to the drive unit 11. The position detector 12 detects the rotational position of the magnet 3 and outputs three-phase sinusoidal signals P1, P2, P3 that change with the rotation of the magnet 3.
The drive unit 11 includes a command signal F and a three-phase signal P of the position detection unit 12.
1, P2, P3 are input, and three-phase sinusoidal currents I1, I2, I3 proportional to the product of both are output. As a result, a rotational force in a predetermined direction is generated by the interaction between the currents I1, I2, I3 to the winding groups of the A, B, C phases and the magnetic flux of the magnet 3.

Next, the cogging torque of this conventional example will be described with reference to FIG. FIG. 3 is a plan development view of the magnet 3 and the armature core 4 of FIG. 1 taken along the line XX ′ and the line YY ′ (the windings are omitted, and the winding grooves are a to x). ). The cogging torque is generated when the magnetic energy stored in the magnetic field between the field part and the armature core changes according to the relative rotation between the two. In particular, it occurs in relation to both the magnetic poles of the field part and the grooves of the armature core,
As shown in FIG. 1, when both the magnet 3 of the field magnet section and the armature core 4 have a magnetic periodicity, a cogging torque of a component (matching component) commonly present in both of them is generated. FIG. 4 shows the distribution characteristics of the magnetic flux density generated by the magnet 3 over the entire circumference (360 degrees). Since the magnetic energy is an amount related to the square of the magnetic flux density, the fundamental harmonic component of the magnetic cycle / waveform of the magnet 3 in the field part having the characteristic shown in FIG. It becomes a wave component. Here, the sine wave component of one rotation once is the first harmonic component. That is, the magnet 3 contains harmonic components such as the 8th, 12th, ...

On the other hand, the magnetic nonuniformity (the amount related to permeance) of the armature core 4 is caused by the winding grooves a to x. Since the winding grooves a to x of the armature core 4 are arranged at equal angular intervals (15 degree intervals), the fundamental harmonic component of the magnetic nonuniformity of the armature core 4 is the 24th order component. Becomes Therefore, based on this, harmonic components such as the 48th, 72nd, ... Are included. Since the cogging torque is generated when the magnetic nonuniformity component of the armature core 4 and the harmonic component of the period / waveform of the magnet 3 are matched (matched), the cogging torque of this conventional example is the 24th. Harmonic components such as the next, the 48th, and so on are generated. The 24th component of cogging torque is
It is directly related to the basic component of the magnetic non-uniformity of the armature core 4 caused by the 24 winding grooves. Generally, the fundamental component of the armature core 4 is considerably larger than the other harmonic components. As a result, a very large cogging torque is generated in this conventional electric motor.

The present applicant has proposed a method for reducing such cogging torque in Japanese Patent Application No. 53-145489. Japanese Patent Application Sho 53-1454
In No. 89, the auxiliary groove is provided in the tooth portion of the armature core to increase the basic harmonic component of the cogging torque and reduce the cogging torque. However, in order to sufficiently reduce the cogging torque by such a method, the fundamental order of the cogging torque needs to be set to a considerably high order, and many auxiliary grooves must be provided in the armature core, which is not practical. Not. Further, even when a large number of auxiliary grooves are provided, the basic component of the cogging torque matches the basic component of the armature core, so that the cogging torque cannot be reduced sufficiently.

An object of the present invention is to provide an electric motor having a field portion having a field magnetic pole and an armature core having a winding groove, in which the cogging torque is extremely small. To do.

Structure of the Invention In the present invention, a permanent magnet material is used, and a P pole (however,
P is a field part having even number of field magnetic poles of 2 or more) at equal angular intervals on the circumference, and an armature core in which 6P winding grooves accommodate three-phase windings. In the electric motor, one of the field magnet portion and the armature iron core is rotatable with respect to the other, and the armature iron core has 6P teeth between the winding grooves. The effective pitch, which is the angle between the centers of the winding grooves at both ends of the tooth, is larger than D = 60 ° / P (where L is an integer), and the effective pitch is D. It has M smaller (where M is an integer) short teeth, and the number of the long teeth and the short teeth is L + M = 6P L ≧ 3 M ≧ 3, and from two or more adjacent short teeth A plurality of short tooth blocks and a plurality of long tooth blocks each including at least one long tooth, and the short tooth block and the long tooth block are circular. The number of the short tooth blocks and the number of the long tooth blocks are respectively arranged to be an integral multiple of 3, and the effective pitch of any of the short teeth and the effective pitch of any of the long teeth are arranged alternately. The above object is achieved by setting the ratio to about G: H (where G and H are integers and G <H).

Further, in the present invention, a permanent magnet material is used, and field poles having P poles (however, P is an even number of 2 or more) having 6 P magnetic field poles at equal angular intervals on the circumference. And an armature core having three-phase windings housed in the winding groove thereof, wherein one of the field part and the armature core is rotatable with respect to the other. In the armature core, 6P teeth are formed between the winding grooves, and an effective pitch, which is an angle between the centers of the winding grooves at both ends of the teeth, is D = 60 ° / P.
It has L larger (where L is an integer) long teeth and M short teeth where the effective pitch is smaller than D (where M is an integer), and the number of the long teeth and the short teeth is L + M. = 6P L ≧ 3 M ≧ 3, and each has a plurality of short-tooth blocks each including at least one short tooth and two or more adjacent long-tooth blocks including the short-tooth block. The long tooth blocks are alternately arranged on the circumference, the number of the short tooth blocks and the number of the long tooth blocks are each an integral multiple of 3, and the effective pitch of any of the short teeth and any of the above The above object is achieved by setting the ratio of the effective pitch of the long teeth to about G: H (where G and H are integers, G <H).

Further, in the present invention, a rotor forming a field portion having permanent magnet magnetic poles of P poles (however, P is an even number of 2 or more) at equal angular intervals on the circumference, the permanent magnet magnetic poles, and a predetermined number. An armature core that is provided with a gap and has three-phase windings housed in 6P winding grooves, and a drive circuit that supplies three-phase current to the three-phase windings as the rotor rotates. The armature core has 6P teeth between the winding grooves, and the effective pitch, which is the angle between the centers of the winding grooves at both ends of the teeth, is D = 60. The number of the long teeth is L (where L is an integer) larger than ° / P and the number of M (where M is an integer) short teeth that is smaller than the effective pitch D. The number is L + M = 6P L ≧ 3 M ≧ 3, and the short tooth block is composed of two or more adjacent short teeth and at least one long tooth. Each having a plurality of long tooth blocks, the short tooth blocks and the long tooth blocks are alternately arranged on the circumference, and the number of the short tooth blocks and the number of the long tooth blocks are each an integer multiple of 3, Further, the ratio of the effective pitch of the arbitrary short tooth and the effective pitch of the arbitrary long tooth is set to about G: H (where G and H are integers, G <H). It has been achieved.

Further, according to the present invention, a rotor forming a field portion having permanent magnet magnetic poles of P poles (where P is an even number of 2 or more) on the circumference at equal angular intervals, and a predetermined gap between the permanent magnet magnetic poles. And an armature core in which windings of three phases are housed in 6P winding grooves, and a drive circuit for supplying three-phase current to the three-phase windings as the rotor rotates. The armature core has 6P teeth formed between the winding grooves, and an effective pitch, which is an angle between the centers of the winding grooves at both ends of the teeth, is D = 60 ° / The number of the long teeth and the number of the short teeth is L, where L is an integer larger than P (where L is an integer) and M are short teeth where the effective pitch is smaller than D (where M is an integer). L + M = 6P L ≧ 3 M ≧ 3, consisting of a short tooth block consisting of at least one short tooth and two or more adjacent long teeth. Each having a plurality of long tooth blocks, the short tooth blocks and the long tooth blocks are alternately arranged on the circumference, and the number of the short tooth blocks and the number of the long tooth blocks are each an integral multiple of 3; By setting the ratio of the effective pitch of any of the short teeth to the effective pitch of any of the long teeth to about G: H (where G and H are integers G <H), the above object is achieved. It was done.

Description of Embodiments FIG. 5 is a developed plan view of a main part of an embodiment of the present invention. In FIG. 5, the magnet 3 attached to the rotor 2 has four magnetic poles arranged at equal angular intervals.
24 winding grooves a to x and 24 teeth are opposed to each other with a predetermined gap. In the 24 winding grooves of the armature core 4,
A winding group of three phases is wound like the winding group of A, B, and C phases in FIG. 1 (not shown). That is, the winding groove a
To f, the winding A1 is wound, the winding groove g to l is wound, the winding A2 is wound, the winding groove m to r is wound, and the winding A3 is wound. A winding A4 is wound from the wire groove s to x, and the windings A1 to A4 are connected in series in consideration of the winding direction to form a phase A winding group. Similarly, the winding B1 is wound over the winding grooves e to j, the winding B2 is wound over the winding grooves k to p, and the winding B is wound over the winding grooves q to v. Wire B3 is wound and wound from winding groove w to d
B4 is wound and the windings B1 to B4 are connected in series in consideration of the winding direction to form a B-phase winding group. Further, the winding C1 is wound over the winding grooves i to n, the winding C2 is wound over the winding grooves o to t, and the winding C is wound over the winding grooves u to b. C3 is wound, winding C4 is wound from winding groove c to h, and windings C1 to C4 are connected in series in consideration of the winding direction to form a C-phase winding group. Is formed. The drive circuit of this embodiment has the same configuration as that of FIG.

In the embodiment shown in FIG. 5, the winding groove a of the armature core 4 is used.
The arrangement of ~ x is arranged at unequal angular intervals, and the effective pitch of the teeth formed between the winding grooves is made nonuniform. Here, the effective pitch of the teeth means the angle between the centers of the winding grooves at both ends of the teeth (definition of the effective pitch). Now, assuming that the number of winding grooves is T = 6 · P = 24 (P is the number of magnetic poles in the field portion, P = 4 in this example), assuming that they are arranged at equal angular intervals, it is effective. The pitch is D = 60 ° / P (D = 60 ° / P in this example)
= 15 °). However, in the embodiment of FIG. 5, the winding grooves a to l are arranged at unequal angular intervals to make the effective pitch of each tooth non-uniform, and the long and short teeth are provided in a predetermined arrangement. There is. Here, a tooth with an effective pitch larger than D is called a long tooth (definition of long tooth), and the effective pitch is D.
Smaller teeth are called short teeth (definition of short teeth). Teeth ab
(Representing teeth by winding grooves on both ends) are short teeth, teeth b-
c is a short tooth, tooth c-d is a short tooth, tooth d-e is a short tooth, tooth ef
Is a short tooth, tooth f-g is a short tooth, tooth g-h is a short tooth, tooth h-i is a long tooth, tooth i-j is a short tooth, tooth j-k is a short tooth, tooth kl is a short tooth. Tooth, tooth l-m is a short tooth, tooth m-n is a short tooth, tooth n-o is a short tooth, tooth op is a short tooth, tooth p-q is a long tooth, tooth q-r is a short tooth, The tooth r-s is a short tooth, the tooth s-t is a short tooth, the tooth t-u is a short tooth, the tooth uv is a short tooth, the tooth v-w is a short tooth, the tooth w-x is a short tooth, and the tooth x. -A is a long tooth. That is, the number of long teeth is L
= 3, the number of short teeth is M = 21. Between winding grooves a to h (a, b, c, d, e, f, g, h) and between winding grooves i to p (i, j,
k, l, m, n, o, p) and between winding grooves q to x (q, r, s, t, u, v,
In w, x) only short teeth are partially concentrated, forming a short tooth block consisting of seven short teeth (not including long teeth). Similarly, between winding grooves h to i (h, i), between winding grooves p to q (p, q), and between winding grooves x to a (x, a)
Has only long teeth partially concentrated and forms a long tooth block consisting of one long tooth (not including short teeth). That is, three sets of short tooth blocks and long tooth blocks are alternately arranged on the circumference. Short teeth a-b, b-c, c-d, d-e, e-
f, f-g, g-h, i-j, j-k, k-l, l-m, m-n, n-o, op, q-
The effective pitch of r, r-s, s-t, t-u, u-v, v-w, w-x is 36.
It is made equal or almost equal to 0 ° / 27 = 13.333 °. The effective pitch of the long teeth h-i, p-q, x-a is 720 ° / 27 =
It is made equal or almost equal to 26.667 °. That is, the ratio of the effective pitch of the short teeth to the effective pitch of the long teeth is 1: 2.
Has been In addition, each long tooth is provided with one auxiliary groove, and the entire armature core groove consisting of the winding groove and the auxiliary groove is equiangularly spaced (360 ° / 27 = 13.333 ° spacing) or approximately equiangularly. Center of each groove at intervals (center viewed from magnetic effect)
Are arranged.

Next, the cogging torque of this embodiment will be described. As described above, cogging torque occurs when the harmonic component of magnetic non-uniformity due to the winding groove of the armature core and the magnetic period / waveform harmonic component due to the magnetic poles of the field part match. . The magnetic period / waveform of the magnet 3 in the field part is a periodic function having a period of one magnetic pole pitch of 360 ° / P of the magnet 3. Therefore, it is sufficient to consider the magnetic nonuniformity of the armature core 4 (the magnetic variation caused by the arrangement of the winding groove and the auxiliary groove) with one magnetic pole pitch of the magnet 3 as the basic period, and the variation amount is generally considered. If is made smaller, the cogging torque becomes smaller. 1 of magnet 3
Winding groove a of the armature core 4 with the magnetic pole pitch as a basic period
FIG. 6 shows the phase relationship when ˜x and auxiliary grooves a ′ to c ′ are viewed. Winding grooves a, f, g, l, m, for storing the A-phase winding group
r, s, x are provided with a phase shift with a phase difference of 1/27 of one magnetic pole pitch (phases a, f, g, l, m, r, s, x of winding grooves differ by more than 6 points) ), The fluctuation range is set to 8/27 of one magnetic pole pitch (1/3 or less of one magnetic pole pitch). Similarly, the winding grooves d, e, j, k, p, q, v, w accommodating the B-phase winding group are provided with a phase shift of 1 pole pitch 1/27, and The fluctuation range is 8/27 of one magnetic pole pitch. Further, the winding grooves b, c, h, i, n, o, t, u accommodating the C-phase winding group are provided with a phase shift with a phase difference of 1/27 of one magnetic pole pitch. The fluctuation range is 8/27 of one magnetic pole pitch. A-phase winding groove group (a, f, g, l, m, r, s, x) and B-phase winding groove group (d, e, j, k, p, q, v) , w) and C-phase winding groove group (b, c, h, i, n,
o, t, u) has a phase difference of 1/3 of one magnetic pole pitch (a phase difference of 120 degrees in electrical angle between the winding groups of A, B, C phases). Further, the auxiliary grooves a ′ to c ′ are located in a phase different from the phases of the winding grooves a to x, and the entire groove formed by the winding grooves a to x and the auxiliary grooves a ′ to c ′ is 1 / The phases are all different with a phase difference of 27. FIG. 7 shows waveforms of magnetic fluctuations of the armature core 4 due to the winding grooves a to x and the auxiliary grooves a'to c '. According to the opening width of each groove, the magnetic variation due to each groove changes gently. Winding grooves a to x and auxiliary groove a '
Since the phases of ~ c 'differ by 1/27, the synthetic magnetic fluctuation (AC) is considerably small. FIG. 8 shows a magnetic variation of the conventional electric motor of FIG. Winding grooves a, g, m, s have the same phase, and winding grooves b, h, n, t
Have the same phase, winding grooves c, i, o, u have the same phase, winding grooves have the same phase d, j, p, v, and winding grooves e, k, q, w have the same phase. Since the winding grooves f, l, r, x have the same phase,
The combined magnetic variation of the conventional electric motor shown in the figure is very large (the auxiliary grooves a'-c 'are not provided in the conventional example of FIG. 1). Comparing FIG. 7 and FIG. 8, it can be seen that the magnetic variation of the electric motor of this embodiment is significantly reduced. As a result, the cogging torque of this embodiment is greatly reduced.

Furthermore, each winding A1, A2, A3, A4, B1, B2, B3, B4, C of this embodiment
The effective pitch of 1, C2, C3, C4 is (24/27 of one magnetic pole pitch) = 1
From 60 degrees (electrical angle) or less (20/27 of one magnetic pole pitch) = 13
It is set to 3.3 degrees (electrical angle) or more. Here, the effective pitch of the winding is the angle formed between the centers of the winding grooves in which the winding is housed. For example, looking at the A-phase winding group, the angle between the winding winding grooves a-f of A1 is 133.3 °.
(5 short teeth), the angle between winding winding grooves g-1 of A2 is 160 ° (4 short teeth and 1 long tooth), A3 wound winding The angle between the wire grooves m-r is 160 ° (4 short teeth and 1 long tooth), and the angle between the winding grooves sx of A4 wound is 133.3 ° (5 Short teeth). As for the B-phase winding group, the angle between the winding grooves e-j of B1 wound is 160 ° (4 short teeth and 1 long tooth), and B2 is wound. The angle between the winding grooves k-p is 133.3 ° (for 5 short teeth), and the angle between the winding grooves q-v wound on B3 is 133.3 °.
The angle between the winding winding grooves wd of B4 is 160 ° (four short teeth and one long tooth).
As for the C-phase winding group, the angle between the wound winding grooves i-n of C1 is 133.3 ° (for 5 short teeth), and the wound winding groove o- of C2 is The angle between t is 160 ° (4 short teeth and 1 long tooth), the angle between the winding grooves u and b of C3 wound is 160 ° (4 short teeth and 1 long tooth) (The long tooth portion of C4) and the angle between the winding grooves ch of the wound C4 are 133.3 ° (five short tooth portions). In this way, if the variation range of the winding groove in which the winding of each phase is housed is made small (1/3 or less of one magnetic pole pitch) and the variation range of the effective pitch of the winding is made small, (From 160 degrees or less to 133 degrees or more), winding work becomes easy and automation is possible.

In the embodiment shown in FIG. 5 described above, auxiliary grooves a ′,
Although b'and c'are provided, the auxiliary groove is not always necessary.
Even if the auxiliary grooves a ', b', and c'in FIG. 7 are eliminated, the synthetic magnetic variation is smaller than that in the conventional example in FIG. Therefore, even if the auxiliary grooves a ', b', and c'in FIGS. 5 and 7 are eliminated, an electric motor with reduced cogging torque can be obtained.
Generally, the cogging torque can be reduced by devising the arrangement of the long teeth and the short teeth and alternately arranging the short tooth blocks and the long tooth blocks each having an integral multiple of three. At this time, if the total number of teeth of a set of adjacent short tooth block and long tooth block is different from a multiple of 3, the tooth phase can be easily changed, and the cogging torque can be easily reduced. Also,
Adjacent 1 by setting the total effective pitch of three consecutive sets of short-tooth block and long-tooth block equal to (360 ° / P) · Q
If the total number of teeth of the short tooth block and the long tooth block of the set is equal to an integral multiple of Q, the phase difference between the winding groups of three phases is 12
It can be equal to 0 degree (electrical angle), and three-phase windings can be evenly arranged (Q = P = 4 in the embodiment of FIG. 5, and the total number of adjacent short tooth blocks and long tooth blocks is 2Q). = 8). That is, as described above, the electric motor having a small cogging torque can be realized according to the present invention even with a simple structure which does not use the auxiliary groove as described above.

If at least one long tooth has an auxiliary groove,
The effect of reducing the cogging torque can be increased. In addition, the effective pitch of the short teeth and the effective pinch of the long teeth are R: R + 1 or
R: R + 3 (R is an integer), auxiliary grooves are provided on the long teeth (and short teeth), and the entire groove of the armature core consisting of the winding groove and the auxiliary groove is divided by R of the effective pitch of the short teeth. If they are arranged at intervals of 1, the cogging torque can be easily reduced. Another example of such a configuration is shown in Table 1.

The configuration of Table 1 (A) is that the effective pitch of the short teeth in FIG. 5 is set to 2 unit angles (1 unit angle is 360 ° / 51 = 7.06 °) and the effective pitch of the long teeth is set to 3 unit angles. Auxiliary grooves are provided on the teeth and the long teeth, and the entire groove including the winding groove and the auxiliary groove is arranged at a unit angle interval. The configuration of Table 1 (B) is the fifth
The effective pitch of the short teeth in the figure is 3 unit angles (1 unit angle is 360
° / 75 = 4.8 °), the effective pitch of the long teeth is 4 unit angles, auxiliary grooves are provided on the short teeth and the long teeth, and the entire groove consisting of the winding groove and the auxiliary groove is at 1 unit angular intervals. It is arranged. In the configuration of Table 1 (C), the effective pitch of the short teeth in FIG. 5 is set to 1 unit angle (1 unit angle is 360 ° / 33 = 10.91 °),
The effective pitch of the long teeth is set to 4 unit angles, auxiliary grooves are provided on the long teeth, and the entire groove including the winding groove and the auxiliary groove is arranged at an interval of 1 unit.

Even when the long tooth block is composed of seven long teeth and the short tooth block is composed of one short tooth, the cogging torque can be reduced. Such a configuration is shown in Table 2.

In the configuration of Table 2 (A), three sets of long tooth blocks each including seven long teeth and one short tooth block including one short tooth are alternately arranged on the circumference (the short tooth and the long tooth in FIG. Replace the number of teeth) and the effective pitch of the short teeth by 1 unit angle (1 unit angle is 360 ° / 45 =
8 °), the effective pitch of the long teeth is set to 2 unit angles, auxiliary grooves are provided on the long teeth, and the entire groove consisting of the winding groove and the auxiliary groove is arranged at 1 unit angular intervals. In the configuration of Table 2 (B), the effective pitch of the short teeth is set to 2 unit angles (1 unit angle is 360 ° / 69 = 5.22 °), the effective pitch of the long teeth is set to 3 unit angles, and the long teeth and the short teeth are set. The auxiliary groove is provided on the first groove, and the entire groove including the winding groove and the auxiliary groove is arranged at a unit angle interval. In the configuration of Table 2 (C), the effective pitch of the short teeth is set to 3
A unit angle (1 unit angle is 360 ° / 93 = 3.87 °), the effective pitch of the long teeth is 4 unit angles, auxiliary grooves are provided on the long and short teeth, and a groove consisting of a winding groove and an auxiliary groove. Is arranged at 1 unit angular intervals.

Further, even when the long tooth block is composed of two long teeth and the short tooth block is composed of six short teeth, the cogging torque can be reduced. Such a configuration is shown in Table 3.

The configuration of Table 3 (A) is such that three sets of short tooth blocks consisting of six short teeth and long tooth blocks consisting of two long teeth are alternately arranged on the circumference, and the effective pitch of the six short teeth is set. To 1 unit angle (1 unit angle is 360 ° / 33 = 10.91 °), and the effective pitches of the two long teeth are 2 unit angle and 3 unit angle, respectively.
An auxiliary groove is provided on the long tooth, and the entire groove including the winding groove and the auxiliary groove is arranged at a unit angle interval. Table 3 (B)
In the above configuration, the effective pitches of the 6 short teeth are all 3 unit angles (1 unit angle is 360 ° / 81 = 4.44 °), and the effective pitches of the 2 long teeth are 4 unit angles and 5 unit angles, respectively. ,
Auxiliary grooves are provided on the long teeth and the short teeth, and the entire groove consisting of the winding groove and the auxiliary groove is arranged at a unit angle interval.

Although the number of magnetic poles of the magnet 3 of the field magnet portion is P = 4 in each of the above-described embodiments, the present invention is not limited to such a case. For example, when the number of magnetic poles of the magnet 3 of the field unit is P = 2, three-phase windings are wound in a winding groove for T = 6P = 12 windings. Table 4 shows an example in which three sets of short tooth blocks made up of short teeth and long tooth blocks made up of one long tooth are alternately arranged on the circumference to reduce the cogging torque.

In the configuration of Table 4 (A), the effective pitch of the short tooth is set to 1 unit angle (1 unit angle is 360 ° / 15 = 24 °), the effective pitch of the long tooth is set to 2 unit angle, and the auxiliary groove is formed on the long tooth. Is provided, and the entire groove formed of the winding groove and the auxiliary groove is arranged at an angular interval of 1 unit. In the configuration of Table 4 (B), the effective pitch of the short teeth is set to 2 unit angles (1 unit angle is 360 ° / 27 = 13.33 °), and the effective pitch of the long teeth is set to 3 unit angles. An auxiliary groove is provided on the first groove, and the entire groove including the winding groove and the auxiliary groove is arranged at a unit angle interval. In the configuration of Table 4 (C), the effective pitch of the short teeth is 3 unit angles (1 unit angle is
360 ° / 39 = 9.23 °), the effective pitch of the long teeth is 4 unit angles, auxiliary grooves are provided on the long and short teeth, and the entire groove consisting of the winding groove and the auxiliary groove is 1 unit angle. It is arranged at intervals.

When the number of magnetic poles of the magnet 3 of the field part is set to P = 2, three sets of short tooth blocks each including one short tooth and three long tooth blocks each including long tooth are alternately arranged on the circumference. Table 5 shows an example in which the cogging torque is reduced by disposing them.

In the configuration of Table 5 (A), the effective pitch of the short teeth is set to 1 unit angle (1 unit angle is 360 ° / 21 = 17.14 °), the effective pitch of the long teeth is set to 2 unit angles, and auxiliary grooves are formed on the long teeth. Is provided, and the entire groove formed of the winding groove and the auxiliary groove is arranged at an angular interval of 1 unit. The configuration of Table 5 (B) shows that the effective pitch of the short teeth is 2 unit angles (1 unit angle is 360 ° / 33 = 10.91 °).
The effective pitch of the long teeth is set to 3 unit angles, auxiliary grooves are provided on the long teeth and the short teeth, and the entire groove including the winding groove and the auxiliary groove is arranged at 1 unit angular intervals. Table 5 (C)
In the configuration, the effective pitch of the short teeth is set to 3 unit angles (1 unit angle is 360 ° / 45 = 8 °), the effective pitch of the long teeth is set to 4 unit angles, and auxiliary grooves are provided on the long and short teeth. Thus, the entire groove including the winding groove and the auxiliary groove is arranged at a unit angle interval.

Although various embodiments have been described, the invention is not limited to such embodiments. For example, P = 4
It is possible to construct an electric motor in which the number of magnetic poles of the field magnet portion is P = 6 by combining the example of 1) and the example of P = 2. Further, the configuration of the embodiment shown in FIG. 5 can be simply doubled to construct an electric motor having double the number of magnetic poles and the number of winding grooves.

A P-pole (P is an even number equal to or greater than 2) permanent magnet magnetic pole is formed on the circumference at equal angular intervals or substantially equal angular intervals, and a permanent magnet magnetic pole is provided at a predetermined interval to form a three-phase winding. An armature part including a wire and an armature core in which windings of three phases are overwound in 6P winding grooves, and one of the field part and the armature part is provided with respect to the other. In an electric motor that is freely rotatable, the armature core has L long teeth (L is a positive integer) whose effective pitch is greater than D = 60 ° / P and M whose effective pitch is less than D (M is Positive integer) short teeth, the number of long teeth and short teeth is L + M = 6P L ≧ 3 M ≧ 3, and a short tooth block consisting of two or more adjacent short teeth and at least one long tooth Long tooth block consisting of teeth,
A plurality of short tooth blocks and long tooth blocks are alternately arranged on the circumference, and the number of short tooth blocks and the number of long tooth blocks are each a multiple of 3, and any short tooth block is formed. The ratio of the effective pitch of G to the effective pitch of any long tooth is G: H.
(G and H are positive integers and G <H), or a short tooth block consisting of at least one short tooth and a long tooth block consisting of two or more adjacent long teeth, Each,
A plurality of short tooth blocks and long tooth blocks are alternately arranged on the circumference, and the number of short tooth blocks and the number of long tooth blocks are each an integral multiple of 3 and are arbitrary short. The ratio of the effective pitch of teeth to the effective pitch of any long tooth is G:
By configuring H (G and H are positive integers and G <H), the cogging torque can be easily reduced.

Here, if the unit angle is set to be smaller than 360 ° / P and the above G and H values are set so that the integral multiple of the unit angle is different from 360 ° / P, the cogging torque can be easily adjusted. And significantly reduced. In particular, when G: H = R: R + 1, the cogging reduction effect is large.

In addition, a permanent magnet material is used to form a field pole portion having P pole field magnetic poles on the circumference at equal angular intervals (equal angular intervals or substantially equal angular intervals) and 6P winding grooves. In the case of an electric motor including an armature core that houses three-phase windings, and one of the field part and the armature core is rotatable with respect to the other, the armature core has an effective pitch. Is D = 60 ° / P
Larger L (where L is a positive integer) long teeth and M whose effective pitch is smaller than D (where M is a positive integer)
Has a short tooth and the number of long and short teeth is L + M = T L ≧ 3 M ≧ 3, and a short tooth block including two or more short teeth and a long tooth block including at least one long tooth The same number of short tooth blocks and long tooth blocks are alternately arranged on the circumference, and the number of short tooth blocks and long tooth blocks are each an integral multiple of 3 to facilitate cogging torque. It can be reduced.

In addition, a permanent magnet material is used to form a field pole portion having P pole field magnetic poles on the circumference at equal angular intervals (equal angular intervals or substantially equal angular intervals) and 6P winding grooves. In the case of an electric motor including an armature core that houses three-phase windings, and one of the field part and the armature core is rotatable with respect to the other, the armature core has an effective pitch. Is D = 360 ° /
L long teeth larger than T (where L is a positive integer),
It has M short teeth whose effective pitch is smaller than D (M is a positive integer), and the number of long teeth and short teeth is L + M = T L ≧ 3 M ≧ 3, and at least one short tooth The same number of short tooth blocks made up of two or more long tooth blocks and short tooth blocks and long tooth blocks arranged alternately on the circumference, and short tooth blocks and long tooth blocks The cogging torque can be easily reduced by making the number of each an integral multiple of 3.

Further, if the sum of the number of teeth of a pair of adjacent short tooth blocks and the number of teeth of a long tooth block is set to be a multiple of 3, the phase of the winding groove can be easily changed, and the cogging torque Effective for reduction. In addition, the effective pitch of three consecutive sets of short tooth block and long tooth block is (360 ° / P) ・ Q
(Where Q is an integer of 2 or more), if the sum of the number of teeth of a pair of adjacent short tooth blocks and the number of teeth of a long tooth block is set to be an integral multiple of Q, three-phase winding The phase of the winding groove can be easily changed while keeping the phase between the groups at 120 degrees (electrical angle), which is effective in reducing the cogging torque.

In addition, the ratio of the effective pitch of the short teeth and the effective pitch of the long teeth is R:
R + 1 (where R is a positive integer) or at least one long tooth is provided with an auxiliary groove so that the entire groove consisting of the winding groove and the auxiliary groove is 1 / R of the effective pitch of the short tooth. If they are arranged at intervals, the cogging torque can be greatly reduced easily (however, the total number of grooves is not an integral multiple of the magnetic pole number P).

In the above embodiments, the magnet is arranged inside and the armature core is arranged outside, but the relationship may be reversed.
Further, the field magnet portion is not limited to the ring-shaped magnet, but may be composed of a plurality of magnet magnetic pole pieces. Besides, various modifications can be made without changing the gist of the present invention.

EFFECTS OF THE INVENTION The present invention realizes an electric motor having a very small cogging torque by providing short and long teeth on an armature core and arranging them in a special relationship. Therefore, according to the present invention, for example, if an electric motor for driving the joint of the robot or a driving motor for the NC device is configured, it is possible to perform highly accurate rotational drive and position control.

[Brief description of drawings]

FIG. 1 is a structural view of a main part of a conventional electric motor, FIG. 2 is a configuration diagram of a drive circuit thereof, FIG. 3 is a plan development view of the electric motor shown in FIG. 1, and FIG. FIG. 5 is a diagram showing the distribution of magnetic flux density, FIG. 5 is a plan development view of an electric motor according to an embodiment of the present invention, and FIG. 6 is a winding when the armature core of FIG. FIG. 7 is a diagram showing the phase relationship of the groove for wire, FIG. 7 is a diagram showing the magnetic variation of the above embodiment, and FIG. 8 is a diagram showing the magnetic variation of the conventional example of FIG. 2 ... Rotor, 3 ... Magnet (field part), 4 ... Armature core, 5, a to x ... Winding groove, 6 ... Tooth, a '...
c '... auxiliary groove, A1 to A4, B1 to B4, C1 to C4 ... winding, h-
i, p-q, x-a ... long tooth, a-b, b-c, c-d, d-e, e-f, f
-G, g-h, i-j, j-k, k-l, l-m, m-n, n-o, o-p, q-r, r
-S, s-t, t-u, u-v, v-w, w-x ... short teeth, h-i, p-q,
x-a ... long tooth block, ah, i-p, q-x ... short tooth block.

Claims (12)

[Claims] 1. A field magnet portion (3) in which permanent magnet magnetic poles of P pole (P is an even number of 2 or more) are formed on the circumference at equal angular intervals or substantially equal angular intervals, and a predetermined gap is provided between the permanent magnet magnetic poles. Is installed in the 3 phase winding (A1 ~ A4, B1 ~ B4, C1 ~ C4) and 6P winding groove (a, b, c, ..., x) And an armature section including the armature core (4), wherein one of the field section and the armature section is rotatable with respect to the other, and the armature core (4) Is L long teeth (h-i, p-q, x-a) whose effective pitch is greater than D = 60 ° / P, and the effective pitch is D
Smaller M short teeth (a-b, b-c, c-d, d-e, e-f, f
-G, g-h, i-j, j-k, k-l, l-m, m-n, n-o, o-p, q-r, r
-S, s-t, t-u, u-v, v-w, w-x), and the number of long teeth and short teeth is L + M = 6P L ≧ 3 M ≧ 3, and 2 The short tooth block (a-h,
i-p, q-x) and a long tooth block (h-i, p-q, x-a) consisting of at least one long tooth are formed in plural, respectively, and a short tooth block and a long tooth block. Are alternately arranged on the circumference, the number of short tooth blocks and the number of long tooth blocks are each an integral multiple of 3, and the effective pitch of any short tooth and the effective pitch of any long tooth A motor with a ratio of G: H (G and H are positive integers and G <H). 2. The armature iron core (4) has a ratio G: H of effective pitches of arbitrary short teeth to effective pitches of arbitrary long teeth, where G: H = R: R +
1 (R is a positive integer) The electric motor according to claim (1). 3. The electric motor according to claim 1, wherein the armature core (4) has the same number of long teeth in each long tooth block and the same number of short teeth in each short tooth block. 4. The armature core (4) has a total effective pitch (360) of three consecutive sets of short tooth blocks and long tooth blocks.
° / P) · Q (Q is an integer of 2 or more), the sum of the number of teeth of a pair of adjacent short tooth blocks and the number of teeth of a long tooth block is equal to an integral multiple of Q. The electric motor as set forth in the range (1). 5. An electric motor according to claim 1, wherein at least long teeth of the armature core (4) have auxiliary grooves (a ', b', c '). 6. The armature core (4) has a ratio of an effective pitch of an arbitrary short tooth to an effective pitch of an arbitrary long tooth of R: R + 1 (R is a positive integer), the winding groove and the auxiliary. The electric motor according to claim (5), in which all the grooves of the armature core made of grooves are arranged at intervals of 1 / R of the effective pitch of the short teeth. 7. A field magnet portion (3) having permanent magnet magnetic poles of P poles (P is an even number of 2 or more) at equal angular intervals or substantially equal angular intervals on the circumference, and a predetermined gap from the permanent magnet magnetic poles. The three-phase windings (A1 to A4, B1 to B4, C1 to C4) and 6P winding grooves (a, b, c, ..., x) provided with the three-phase windings An armature core (4) comprising: an armature part (4), wherein either one of the field part and the armature part is rotatable with respect to the other. ) Are L long teeth with an effective pitch larger than D = 60 ° / P (eg, the part 2 in Table 2 (A)) and M short teeth with an effective pitch smaller than D (eg, Table 2). (1 part of (A)), the number of long teeth and short teeth is L + M = 6P L ≧ 3 M ≧ 3, and a short tooth block including at least one short tooth (eg, Table 2
(1) of (A)) and a long tooth block consisting of two or more adjacent long teeth (eg, 2 block of Table 2 (A)) are formed in plural numbers, respectively. The tooth blocks are alternately arranged on the circumference, the number of short tooth blocks and the number of long tooth blocks are each an integral multiple of 3, and the effective pitch of any short tooth and any long tooth An electric motor whose effective pitch ratio is G: H (G and H are positive integers and G <H). 8. The armature iron core (4) has a ratio G: H of effective pitches of arbitrary short teeth to effective pitches of arbitrary long teeth, where G: H = R: R +.
1 (R is a positive integer) The electric motor according to claim (7). 9. The electric motor according to claim 7, wherein the armature core (4) has the same number of long teeth in each long tooth block and the same number of short teeth in each short tooth block. 10. The armature core (4) has an effective pitch of (360) as a whole of three consecutive sets of short tooth blocks and long tooth blocks.
° / P) · Q (Q is an integer of 2 or more), the sum of the number of teeth of a pair of adjacent short tooth blocks and the number of teeth of a long tooth block is equal to an integral multiple of Q. The electric motor as set forth in the range (7). 11. The electric motor according to claim 7, wherein at least long teeth of the armature core (4) have auxiliary grooves. 12. The armature core (4) has a ratio of the effective pitch of any short tooth to the effective pitch of any long tooth is R: R + 1 (R is a positive integer), and the winding groove and the auxiliary The electric motor according to claim (11), wherein all of the grooves of the armature core made of grooves are arranged at intervals of 1 / R of the effective pitch of the short teeth.