JPS63198559A - Rotor magnet for motor - Google Patents

Abstract

PURPOSE:To reduce the irregularity of a torque in a motor by reducing a magnetic interference between upper and lower groups. CONSTITUTION:A rotor magnet 15 is composed by securing a concentric cylindrical magnet 22 through a collar of nonmagnetic material, such as plastic to a rotor shaft 14. N-, S-poles are alternately magnetized at a predetermined circumferential pitch at the magnet 22, and a nonmagnetized region 23 of predetermined width is formed at the axial center of the magnet 22. Thus, a magnetic interference between an upper group and a lower group can be reduced by the region 23 near the vicinity of the bent part of a yoke to reduce the irregularity of a torque between upper and lower exciting coils, thereby alleviating a vibration noise.

Description

[Detailed Description of the Invention] [Technical Field] The present invention provides NS on the peripheral surface of a PM type step motor rotor, etc.
This relates to a rotor magnet consisting of alternating multi-pole magnetization.

[Prior art]

This type of rotor magnet has conventionally been constructed by alternately magnetizing NSs in multiple poles over the entire circumferential surface of the rotor.

First, a step motor, which is a typical example of a motor in which this type of rotor magnet is used, will be explained.

A step motor is adjusted so that the pole teeth of a yoke having a plurality of excitation coils are opposed to the magnetic poles of a rotor, and the rotor is sequentially rotated by a constant angle by applying pulse current to each excitation coil in a constant order. ing.

FIG. 4 is an exploded perspective view of this step motor.
The figure is a longitudinal sectional view of the motor of FIG. 4.

In FIGS. 4 and 5, the illustrated step motor has a two-stack structure, upper and lower, and 11.12 is an outer yoke of each stack, and lla and 12a are each outer yoke 1.
1.12 is a comb-shaped magnetic pole; 13.13 is an inner yoke of each stack; 13a;

13b is a comb-shaped magnetic pole of each inner yoke, 1-4 is a rotor shaft, 15 is a rotor magnet in which NS is alternately made into various magnetic poles, and 17.19 is the excitation of each stack formed by winding a coil around a bobbin. The coil is shown.

In the motors of FIGS. 4 and 5, four sets of yokes 11, 12, 13, and 13 are connected to each other as shown in FIG.
A stator section is constructed by joining them with a shift of one-tenth of a pinch at a time, and rotor magnets 15 are disposed coaxially and facing each other within the stator section.

The yoke is provided with excitation coils 17, which constitute two stacks.
19 is wound.

The excitation phase formed by the excitation coil 17.19 (
For example, when power is applied sequentially according to a predetermined sequence (for example, 4 phases), the comb teeth (poles) of each yoke are lla, 12a,
13a and 13b are magnetized to N or S depending on the energization mode.

As the magnetized pole teeth of the yoke and the magnetic poles of the rotor magnet 15 repeat attraction and repulsion, the rotor magnet 15 rotates and torque is obtained.

FIG. 6 shows the comb-like pole teeth 11 a , l 2 a s 13 a -1 of four sets of yokes 11, 12, 13, 13.
FIG. 7 is a developed view showing the arrangement of magnets 3b, and FIG. 7 shows a conventional rotor magnet.

By the way, in the conventional rotor magnet, as shown in FIG. 7, the NS is alternately multi-poled over the entire circumferential surface of the rotor.

On the other hand, the four sets of yokes (teeth 11a, 12a).

13a and 13b are arranged one-fourth of a pitch apart from each other as shown in FIG. As shown in FIG. 6, they overlap each other to form a joint folded portion (indicated by thickness C).

Originally, a group of upper and lower yokes GISG2, that is, pole teeth 11a, 13a and 12a, 13b for each stack
If the excitation coil 1 of each stack is magnetically separated,
No mutual interference of torques due to 7.19 occurs, and no variation in torque occurs.

However, in the conventional rotor magnet (FIG. 7), the magnetic flux from the magnetic pole near the axial center of the rotor magnet 15 passes through the joint bent portion (thickness C portion) of the yoke 13.13 to both the upper and lower yokes. The problem is that magnetic interference occurs between the upper and lower groups (stack), which causes variations in motor output torque and uneven detent torque, which not only reduces efficiency but also causes vibration and noise. was there.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotor magnet for a motor that can solve the problems of the prior art described above and can reduce variations in torque by reducing magnetic interference between upper and lower groups.

[Means to achieve the purpose]

The present invention provides a motor rotor magnet in which N poles and S poles are arranged alternately at a predetermined pitch in the circumferential direction on the circumferential surface of the rotor, and a non-magnetized area or a magnetic pole relief part of a predetermined width is provided in the axial center of the rotor. By providing this, the above object is achieved.

〔Example〕

Hereinafter, each embodiment of the present invention shown in FIGS. 1 to 3 will be specifically described with reference to FIG. 4 or FIG. 6.

FIG. 1 shows a first embodiment of a rotor magnet according to the invention.

The rotor magnet 15 shown in FIG. 1 is constructed by fixing a concentric cylindrical magnet 22 to the rotor shaft 14 via a collar 21 made of a non-magnetic material such as plastic or aluminum.

The magnet 22 has an N pole and an S pole with a predetermined pinch in the circumferential direction.
Although the poles are alternately magnetized, a non-magnetized region 23 of a predetermined width is provided in the axial center of the magnet 22 .

The width of this non-magnetized area 23 can be determined as appropriate, but for example, the width of the upper and lower inner yokes 13 and 13 shown in FIG.
It is possible to greatly reduce the magnetic interference between the upper and lower groups by making the thickness C greater than the thickness C of the bent portion of the joint, and to set the thickness to a value that does not exceed the distance B between the tips of the comb teeth 11a and 12a of the upper and lower outer yokes. can.

According to the rotor magnet 15 shown in FIG. 1, since the non-magnetized region 23 of a predetermined width is provided in the axial center of the rotor 15,
It is possible to reduce magnetic interference between the upper and lower groups near the joint bending portion C of the yoke 13.13, and thereby,
It was possible to reduce variations in torque between the upper and lower excitation coils 17, 19 (Fig. 4), and to reduce vibration noise.

FIG. 2 shows a second embodiment of the rotor magnet according to the invention.

The rotor magnet 15 shown in FIG. 2 is also constructed by fixing a concentric cylindrical magnet 22 to the rotor shaft 14 via a collar 21 made of a non-magnetic material such as plastic or aluminum.

The point that N and S poles are alternately magnetized on the circumferential surface of the magnet 22 with predetermined pinches in the circumferential direction is the same as in the case of FIG. 1, but in this embodiment, the axial center of the magnet 22 is A magnetic pole relief portion 25 of a predetermined width is formed in the portion.

This magnetic pole relief portion 25 has a predetermined size, for example, 0.5 to 2.
0*n), and the groove portion may be magnetized in the same way as above and below it.

Further, the width of the magnetic pole relief part 25 can be determined as appropriate, but it should be larger than the thickness C (FIG. 6) of the joint bending part of the yoke 13.13 and the comb teeth of the upper and lower outer yokes, as in the case of the first embodiment. It can be set to such an extent that it does not exceed the distance B (FIG. 6) between the tips of 11a and 12a.

With the rotor magnet 15 shown in FIG. 2, the same effects as in the case of the first embodiment shown in FIG. 1 described above were obtained.

FIG. 3 shows a third embodiment of the rotor magnet according to the invention.

In the rotor magnet 15 shown in FIG. 3, a collar 21 made of a non-magnetic material such as plastic or aluminum and having an intermediate flange 27 is fixed to the rotor shaft 14, and separate pieces are attached above and below the flange 27 on the circumferential surface of the collar 21. It is constructed by fixing cylindrical (or annular) magnets 28 and 28.

The outer diameter of each magnet 28, 28 and the outer diameter of the flange 27 are substantially the same, and the flange 27 forms a non-magnetized region, that is, a portion corresponding to the region 23 in FIG.

The rotor magnet 15 shown in FIG. 3 can also achieve the same effect as the first embodiment or the second embodiment described above, and by reducing the upper and lower magnetic interference, the torque of the upper and lower coils can be reduced. It was possible to reduce the variation in

Note that the rotor magnet according to the present invention can be used as a rotor magnet for a motor with a similar structure such as a synchronous motor in addition to a step motor, and can produce similar effects.

〔effect〕

As is clear from the above description, according to the present invention, in a motor magnet in which N poles and S poles are arranged alternately at a predetermined pitch in the circumferential direction on the circumferential surface of the rotor, there is a gap having a predetermined width in the axial center of the rotor. By providing a magnetized region or a magnetic pole relief part, it is possible to reduce magnetic interference between the upper and lower stacks near the yoke joint folding diagram, thereby making it possible to reduce variations in torque between the upper and lower coils. Ta.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a first embodiment of a rotor magnet according to the present invention, FIG. 2 is a perspective view of a second embodiment of a rotor magnet according to the present invention, and FIG. 3 is a perspective view of a third embodiment of a rotor magnet according to the present invention.
4 is an exploded perspective view of a motor suitable for using the rotor magnet according to the present invention, FIG. 5 is a longitudinal sectional view of the motor shown in FIG. 4, and FIG. 6 is a longitudinal sectional view of the motor shown in FIG. 4. Partial development view showing the arrangement of the upper and lower yokes in the motor, Part 7
The figure is a perspective view of a conventional rotor magnet. 14-...--Rotor shaft, 15----------
・Rotor, 22.28-----Magnet, 2
3-------Non-magnetized area, 25----
----Magnetic pole relief part, 27-------- Non-magnetized area (flange of collar). Agent Patent Attorney Yasushi OotoFigure 4

Claims (1)

[Claims] (1) In a motor rotor magnet in which N and S poles are arranged alternately at a predetermined pitch in the circumferential direction on the circumferential surface of the rotor, a non-magnetized area or a magnetic pole relief part of a predetermined width is provided in the axial center of the rotor. A motor rotor magnet characterized by: