JPS61150657A - Permanent magnet type stepping motor - Google Patents

Abstract

PURPOSE:To reduce by half a step angle from P/4 to P/8 without altering the pitch of pole teeth by splitting a rotor pole to displace by 1/4 the pole teeth pitch P, and displacing by P/8 between the adjacent poles at the pitch of the pole teeth of a stator. CONSTITUTION:The pole teeth 6-1a, 6-2a and 6-1b, 6-2b of rotor poles 6-1, 6-2 mounted by splitting at both axial sides of a permanent magnet 7 secured to a rotational shaft are displaced at 1/4 of the pitch P of the pole teeth. Coils 2-1-2-8 are respectively wound on the poles 1-1-1-8 of the stator projected to the inside of the yoke of the peripheral shape, stator pole teeth 1-A-8-A are formed at the ends, and the pitch of the pole teeth 1-A-8-A is increased by 1/8 from the pitch P of the pole teeth of the rotor. Thus, even if the pitches P are the same, the stepping angel of the motor is reduced by half from P/4 to P/8.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a permanent magnet type stepping motor, particularly a permanent magnet type stepping motor having a rotor in which a permanent magnet is sandwiched between rotor poles having pole teeth on the outer periphery. This relates to stepping motors.

[Prior art]

Figure 1 (al, (bl) shows a conventional permanent magnet type stepping motor, in which magnetic poles 1-1 to 1-8 of the stator are arranged radially inward on the annular yoke of the stator core 1. The pole teeth 1-A to 8-A and 1-B to 8-B adjacent to each other in the axial direction are arranged at approximately equal pitches at the tip of each magnetic pole. Stator windings 2-1 to 2-8 are respectively wound around 1-8 to form a stator,
Pole teeth 1a to 10a facing inside the stator through a gap
and rotor poles 6-1 and 6-2 with 1b to 10b.
are integrally fixed to a rotor shaft 5 with a permanent magnet 7 in between, and the rotor shaft 5 is rotatably supported by bearings 4, 4 provided on an end bracket 3.

The stator windings 2-1 to 2-8 are arranged at points symmetrical positions with respect to the center of the stator as shown in FIG. Four sets of windings connected in series are connected in parallel to a power source E so that each winding can be sequentially energized.

In order to explain the operation of this stepping motor, Fig. 1(d) shows the pole teeth 1-A to 8-A, 1-B to 8-B of the stator and the pole teeth 1a to 10a, 1b of the rotor. ~10b
Arrangement of rotor pole teeth 1a to 10a and 1b to 10b provided on rotor poles 6-1 and 6-2, respectively, which sandwich the permanent magnet 7 in a developed view showing the relative position of the permanent magnet 7. The pitch is when the tooth width is 'AP' (in this example, P is 36°)
P (36°) to each other, and the pole teeth 1-A to B- of the stator
A, 1-B to 8-B tooth width is AP, arrangement pitch is P+V
4P (45 degrees), and the pole teeth of the rotor pole 6-1 and the pole teeth of the rotor pole 6-2 are arranged to be shifted by the tooth width (18 degrees).

In FIG. 1(d), the switch S-1 is turned ON, and current flows through the stator windings 2-1 and 2-5, and the stator pole tooth 1 is turned on.
-A and 5-A are shown aligned to face the pole teeth 1a and 6a of the rotor, respectively. Next, to rotate the rotor to the right, turn off switch S-1 and switch S-1.
-2 is turned on and current flows through @ wires 2-2 and 2-6. As a result, pole teeth 2-A and 6-A are magnetized, and the rotor pole teeth 2-A and 6-A are magnetized.
a and 7a are attracted by the pole teeth 2-A and 6-A of the stator, respectively, and rotated in the right direction by 'AP (9 degrees), so that the respective pole teeth face each other and come to rest in alignment. With this operation, the rotor is 'A'
Rotate to the right by P (9°), and the rotation angle A at this time
P (9°) is one step angle.

To rotate further to the right, turn off switch S-2.
When switch S-3 is turned on, windings 2-3 and 2-7
When current flows through the stator, the pole teeth 3-A and 7-A are magnetized, and the rotor's pole teeth 3a and 8a are attracted to the stator's pole teeth, rotate by 4P in the right direction, and become the pole teeth. are lined up facing each other and stand still.

In this stepping motor, the rotor rotates by one step angle each time the energized windings are switched as described above, and the number of energized windings switched is proportional to the rotation angle, so the control device can have a simple configuration. There are advantages.

As mentioned above, in the operation of a stepping motor, the rotor rotates by l step angle each time the energized winding is switched, so this one step angle is the minimum control unit, and this angle is the pitch P of the pole teeth of the rotor. Therefore, in order to reduce the step angle, increase the number of pole teeth provided on the rotor pole and make the arrangement pitch finer, as shown in Figure 1 (bl), and increase the number of pole teeth on the rotor pole. It is necessary to increase the number of pole teeth provided on the stator magnetic poles facing the stator magnetic poles, and to make the arrangement pitch of the pole teeth arranged on the same magnetic pole finer to match the arrangement pitch of the rotor pole teeth. The number of pole teeth of the rotor is N times the number in Figure 1 + d), and the arrangement pitch is 1/N.
By setting the pitch of the pole teeth provided on each magnetic pole of the stator to the same <17N, one step angle can be reduced to 1/N.

However, due to limitations in manufacturing technology, there is a limit to the number of pole teeth that can be arranged on a rotor of a certain diameter, and it has been particularly difficult to manufacture small stepping motors with minute step angles.

[Purpose of the invention]

The present invention solves the problems of the conventional stepping motors as described above and realizes a small angle stepping motor.

[Summary of the invention]

The permanent magnet stepping motor of the present invention has a stator formed by installing a plurality of magnetic poles radially in a cylindrical yoke, providing pole teeth at the tips of the magnetic poles, and winding each magnetic pole with a winding wire. , a permanent magnet stepping motor comprising a rotor having pole teeth on its outer periphery and a permanent magnet sandwiched between two rotor poles facing the pole teeth of the stator with an air gap between them. , each of the above two rotor poles in the axial direction 2
The position of the pole teeth of each divided rotor pole is shifted by a pitch angle of half the pitch of the pole teeth,
The pole teeth of the other rotor ball facing each other via a permanent magnet are arranged so as to be shifted by a pitch angle of 1/4 of the arrangement pitch of the pole teeth, and the pole teeth provided on the magnetic poles of the stator are The tooth width is the pitch of the corresponding pole teeth provided with the rotor ball above: Q+1/
It is characterized by being arranged so that it becomes 8P.

[Structure of the invention]

In the present invention, as shown in FIG.
The divided rotor balls 6-1a and 6-
If the pole teeth of 1b have a tooth width of AP (20 degrees in this example), they are arranged so as to be shifted by 'A P (20 degrees) from the other rotor balls holding the permanent magnet 7 between them. The pitch deviation from the pole teeth of the stator is AP (10°), the tooth width of the stator pole teeth is 'A P (20°), and the arrangement pitch of the pole teeth is S + 1/8. P (45°).

Since the stepping motor of the present invention has the above-described configuration, when the winding 2-1 is energized, the magnetic pole 1-1 is excited, and the pole teeth 1-A and 1-B and the rotor's pole teeth 6-1. 6-2, the pole teeth 1-A and 1-8 of the stator are excited to the north pole, and the rotor ball 6 facing the pole tooth 1-A
Since the -1 pole teeth 6-1a and 6-1b are both north poles due to the polarity of the permanent magnet 7, the rotor balls are repelled but no rotational force is generated. On the other hand, since the pole teeth 6-2a and 6-2b of the rotor ball 6-2 facing the pole tooth 1-B are S poles, an attractive force acts on the N pole of the magnetic pole 1-B, but the stator Pole teeth 6-2a and 6 of rotor ball 6-2 with respect to pole tooth 1-H
-2b are opposed to each other by approximately A of their tooth widths, and the suction forces to the right and left are equal, so the rotational forces to the right and left are balanced, and they are stationary at the illustrated position.

Next, when the winding 2-1 is de-energized and the winding 2-2 is energized,
The magnetic pole 1-2 is excited to the N pole, and the pole teeth 2-B of the stator and the pole teeth 6-2a and 6-2b of the rotor ball 6-2 have different polarities and attract each other, and the rotor moves to the right. The pole teeth 2-B of the stator and the pole teeth 6-2a and 6- of the rotor ball 6-2 rotate in the direction of
At the position where 2b and 2b face each other by approximately 2 tooth widths, the rotational forces on the right and left sides are balanced and come to rest. The moving angle of the rotor at this time is 1/8 pitch angle of the arrangement pitch P of the pole teeth of the rotor (in this example, 5
), which is one step angle of this stepping motor.

This stator pole tooth 2-B and the pole tooth 6-2 of the rotor ball
-2a and 6-2b will be further explained in detail with reference to FIG. Figure 3 shows that when a magnetic field is acting between the stator pole teeth and the rotor pole teeth, the horizontal axis is the deviation angle θr of the opposing surfaces of both pole teeth, and the vertical axis is the generated torque T. In the θr-T curve shown in FIG. 1, the deviation angle θr and the torque T increase according to the saturation curve, and the torques T and T2 correspond to the deviation angles θ1 and θ2, respectively.

Stator pole tooth 2-B and rotor pole tooth 6-2a.

6-2b, the rotor pole tooth 6-2a is compared to the stator pole tooth 2-B.
The deviation angle θr at which and 6-2b occur is the polar tooth 6-2a.
, there is a large shift of θ2 to the left, and the pole tooth 6-2
Regarding b, there is a small deviation in the right direction by θ, and the rightward torque T2 acting on the pole tooth 6-2a is larger than the leftward torque T acting on the pole tooth 6-2b. The torque acting on the rotor acts to the right at Tz Tt and rotates to the right, and each of the pole teeth 6-2a and 6-2b has an equal deviation angle θr from the stator pole tooth 2-B. It rotates to a position where the pole teeth 6-2a and 6-2b are rotated, and comes to rest at a position where the torque acting on each of the pole teeth 6-2a and 6-2b is balanced. The rotation angle of the rotor at this time is 1/8P, which is the step angle of the stepping motor according to the present invention.

Considering the pole teeth 6-1a and 6-1b of the rotor ball 6-1, which are opposed to the pole teeth 2-A of the magnetic pole 1-2 excited by the winding 2-2, the pole teeth 2-A of the stator is magnetized to the N pole, and the opposing pole teeth 6-1a and 6-1b of the rotor are both N-pole.
Since the rotor is a pole, a repulsive force acts on the pole teeth of the rotor, and by sequentially energizing the windings of the magnetic poles, the rotor advances by one step angle, that is, 1/8P.

In addition, in the above embodiment, each stator magnetic pole 1-1 to 1-8 has 1
Although this is an example in which many pole teeth are formed, in reality, many pole teeth are provided on the rotor pole, and each stator magnetic pole 1-1 to 1-8
A plurality of pole teeth are provided correspondingly.

4 to 7 are explanatory diagrams in the case where each stator is provided with 2, 3, 4, and 5 pole teeth, respectively, and the operation and effect thereof are the same as in the first embodiment.

〔Effect of the invention〕

As described above, according to the present invention, even if the arrangement pitch P of the pole teeth of the rotor is the same as that of the prior art stepping motor,
The rotor pole is divided into two parts and placed offset by 'AP,
The positions of the pole teeth of the opposing stator magnetic poles are shifted by 178P between adjacent magnetic poles with respect to the pitch S in which the magnetic poles are equally distributed, thereby reducing the pitch P of the pole teeth of the stepping motor and rotor of the prior art. The step angle of the conventional stepping motor is WP, which is the same as that of the conventional stepping motor.
There is a big profit that can be made with /B P and %.

In addition, in the above embodiment, for convenience of explanation, the case where the number of pole teeth of the stator magnetic poles corresponding to the pole teeth of the rotor is one is shown, but the arrangement pitch of the pole teeth of the rotor poles is set to 1/N, and this By setting the arrangement pitch of the pole teeth provided on each magnetic pole of the opposing stator to 1/N, the l step angle can be set to 1/N.

[Brief explanation of the drawing]

Figures 1(a) and (b) are a vertical side view and a front view of a conventional permanent magnet stepping motor, respectively, Figure 1(C) is its circuit diagram, and Figure 1(d) is the stator and rotor. FIG. 2 is a developed view of the pole teeth of the stator and rotor of the permanent magnet stepping motor of the present invention, FIG. 3 is an explanatory diagram of its rotational torque, and FIGS. 4 to 7 FIG. 2 is an explanatory diagram of another embodiment of the present invention. 1... Stator iron core, l-1 to l-8... Magnetic pole, 1-
A~8-A, 1-BN2-B...Stator pole tooth, 1a
~10a, lb~10b... rotor pole teeth, 2-1~
2-8... Stator winding, 3... End bracket,
4...Bearing, 5...Rotor shaft, 6-1.6-2...
・Rotor pole, 6-1a, 6-1b, 6-2a, 6-
2b.--Pole tooth, 7. Permanent magnet, S-1 to S-4.
··switch.

Claims (1)

[Claims] A stator formed by installing a plurality of magnetic poles radially in a cylindrical yoke, providing pole teeth at the tips of the magnetic poles, and winding a winding around each magnetic pole, and the stator having pole teeth on the outer periphery. In a permanent magnet stepping motor comprising a rotor formed by sandwiching a permanent magnet between pole teeth and two rotor poles facing each other with an air gap, each of the two rotor poles is divided into two parts in the axial direction, and the position of the pole teeth of each divided rotor pole is shifted by a pitch angle of half the pitch of the pole teeth arrangement pitch, and the other rotating part that holds the permanent magnet is The position of the pole teeth of the child pole is shifted by a pitch angle of 1/4 of the arrangement pitch of the pole teeth, and the number of magnetic poles of the stator is Q, and the pitch S of these magnetic poles is S=360°/ Let Q be the number of pole teeth arranged on the rotor pole, and let the arrangement pitch P be P.
A permanent magnet type stepping motor characterized in that the pitch of corresponding pole teeth provided on adjacent magnetic poles of a stator is arranged so that =360°/R and the pitch of corresponding pole teeth is Q+1/8P.