JPS62189965A - Stepping motor - Google Patents

Abstract

PURPOSE:To improve the characteristics of a rotor such as the magnetic effi ciency, angle accuracy, etc., and its mechanical strength by interposedly overlap ping a disc-shaped magnetic substance between a pair of permanent magnets. CONSTITUTION:A rotor 4 can improve its mechanical strength of permanent magnets 1 and 2 by interposedly overlapping a disc-shaped magnetic substance 3 between a pair of permanent magnets 1 and 2. Moreover, as a part of mag netic circuits of each stator 7 and 8a is composed of the magnetic substance 3 and is divided by each stator 7 and 8, the magnetic path becomes short. The characteristics of the rotor 4 such as the magnetic efficiency, the angle accuracy, etc., can therefore be improved.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a step motor.

[Background technology]

Conventional examples are shown in FIGS. 7 to 12. That is, this step motor has a plurality of magnetic poles N magnetized in the axial direction,
A rotor 51 having disk-shaped permanent magnets 50 formed such that S has different magnetic poles alternately in the circumferential direction; The inner teeth 52 and the outer teeth 53 protruding inwardly from the outer circumferential side of the inner teeth 52 are substantially on the same plane so that the distance between the same magnetic poles N in the circumferential direction of the permanent magnet 50 is π shifted from each other by 1 electrical angle. The permanent magnets 50
A pair of stators 54 and 55 that are mutually shifted in the circumferential direction by π/2 of the electrical angle on both sides, and these stators 54
, 55, and excitation coils 56, 57 which are arranged on opposite sides in the axial direction and which excite each of the stators 54, 55. 58 and 59 are housings that also serve as yokes for the stators 54 and 55.

However, in this step motor, each excitation coil 56.
As shown in FIG.
The excitation coil 56.57 as in the state of part a of the pulse train designated ta+ in FIG. 12 for the switching of 6.57.
Taking as an example the case where a voltage is simultaneously applied to the 11th
As shown in the figure, the inner teeth 52 of the stator 54 and the stator 55
The external teeth 53 of the stator 54 are excited to the magnetic pole N, and the external teeth 5 of the stator 54
3 and the internal teeth 52 of the stator 55 are excited by the magnetic pole S, the magnetic flux caused by these flows through a magnetic circuit as shown by thin arrows in FIGS. 8 and 11. That is, the internal teeth 52 of the stator 54 → the magnetic pole S of the permanent magnet 50 → the internal teeth 52 of the stator 55 → the housing 59 → the external teeth 53 of the stator 55 → the magnetic pole S of the permanent magnet 50 - the magnetic pole N of the permanent magnet 50
→ External teeth 53 of stator 54 → Housing 58 → Internal teeth 52 of stator 54.

In this way, the magnetic circuit connects both stators 54 . , 55, the magnetic path is long, resulting in poor magnetic efficiency and poor characteristics such as angular accuracy. Furthermore, since the permanent magnet 50 is flat, it has a drawback of low mechanical strength.

[Purpose of the invention]

An object of the present invention is to provide a step motor that can improve characteristics such as magnetic efficiency and angular accuracy and the mechanical strength of permanent magnets.

[Disclosure of the invention]

The step motor of the present invention includes a pair of disc-shaped permanent magnets formed such that a plurality of magnetic poles magnetized in the axial direction alternately become different magnetic poles in the circumferential direction, and the different magnetic poles face each other in the axial direction. a rotor that faces the pair of permanent magnets and is superimposed with a disc-shaped magnetic body interposed between the pair of permanent magnets; and a rotor that is arranged on both sides of the pair of permanent magnets in the axial direction and projects radially outward. The inner teeth and the outer teeth protruding inwardly from the outer circumferential side of the inner teeth face each other in substantially the same plane so that the same magnetic poles in the circumferential direction of the permanent magnet are shifted by π from each other with 1 electrical angle. The magnet is equipped with a pair of stators that are arranged on both sides of the permanent magnet and are shifted from each other in the circumferential direction by π/2 of the electrical angle, and excitation coils that respectively excite these stators.

According to the structure of the present invention, the rotor is arranged so that a disk-shaped magnetic body is interposed between a pair of permanent magnets and superimposed on each other, so that a part of the magnetic circuit of each stator is constituted by the magnetic body, The magnetic path becomes shorter and the magnetic path becomes shorter. Therefore, characteristics such as magnetic efficiency and angular accuracy and mechanical strength of the permanent magnet can be improved.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 6. That is, this step motor has a pair of disc-shaped permanent magnets 1.2 formed in such a way that a plurality of axially magnetized magnetic poles N and S alternately become different magnetic poles in the circumferential direction. A rotor 4 which faces each other so that different magnetic poles face each other and is stacked on top of the other with a disk-shaped magnetic body 3 interposed between the pair of permanent magnets 1.2, and the pair of permanent magnets 1.2.
Internal teeth 5 are arranged on both sides of the permanent magnet 1.2 in the axial direction and protrude radially outward, and external teeth 6 protrude inward from the outer peripheral side of the internal teeth 5 in the circumferential direction of the permanent magnet 1.2. A pair of magnetic poles facing each other in substantially the same plane so that the same magnetic poles are offset by π from each other with 1 electrical angle, and mutually offset by π/2 of the electrical angle in the circumferential direction on both sides of the permanent magnet 1.2. stator 7.8, and excitation coils 9, 10 that excite each stator 7.8, respectively.

The rotor 4 is composed of a rotating shaft 11, a bushing I2 attached to the rotating shaft 11, a permanent magnet 1.2 and a magnetic body 3 attached to the bushing 12. Details of the permanent magnets 1, 2 and the magnetic body 3 are shown in FIG. That is, a plurality of magnetic poles N, S magnetized in the axial direction
are formed at equal intervals in the circumferential direction so as to alternately have different magnetic poles, and the permanent magnets 1.2 are formed at regular intervals so that the same magnetic poles N in the circumferential direction are
The electrical angle, that is, 2π, is shifted by an electrical angle of π, so that different magnetic poles appear on both sides of the permanent magnets 1 and 2 in the axial direction.

The stators 7.8 are each formed of a magnetic thin plate,
The inner teeth 5 and the outer teeth 6 are integrally formed from the same magnetic thin plate by punching or the like, and the inner teeth 5 are formed on the inner ring 14.
The outer teeth 6 are supported by an outer ring 15, and the inner teeth 5 and the outer teeth 6 are connected by connecting portions 13 at a plurality of locations, that is, four locations in the embodiment. The inner teeth 5 and the outer teeth 6 are formed at regular intervals, the same as the number of magnetic poles N appearing in the circumferential direction of the permanent magnet 1.2. Pairs of positioning protrusions 16 are formed on the periphery of the outer ring 15.

The housings 17 and 18 also serve as yokes, each having an inner cylinder part 19 and an outer cylinder part 20, and a bearing 21 at the center.
are provided, and the rotating shaft 11 of the rotor 4 is supported in each bearing 21. Circumferential grooves 22 and 23 are formed on the outer circumferential side of the tip of the inner cylindrical portion 19 and on the inner circumferential side of the tip of the outer cylindrical portion 20, respectively, to lock the inner circumferential ring 14 and the outer circumferential ring 15 of each stator 7.8. The positioning protrusion 1 is also inserted into a pair of positioning notches (not shown) formed at the tip of the outer cylindrical portion 20.
6 is engaged to restrict rotation in the circumferential direction. A pair of housings], 7.18 are joined so that the stator 7.8 faces each other, but at this time, the stator 7.8
The internal teeth 5 and external teeth 6 are made to deviate from each other by an electrical angle of π/2 in the circumferential direction. Also, the permanent magnet 1.2 is assembled so as to be located between the pair of stators 7.8. In addition, permanent magnet 1
, 2 and the internal teeth 5 and external teeth 6 are set smaller than the radial gaps between the internal teeth 5 and external teeth 6 to reduce leakage magnetic flux.

The excitation coils 9 and 10 are wound around a coil frame 24 made of an insulator, and this coil frame 24 is connected to the housing 17.
It is housed between the inner cylinder part 19 and the outer cylinder part 20 of 18.

This step motor is similar to the 12th step motor described in the conventional example.
Applied voltages are supplied to the excitation coils 9 and 10 in the same relationship as shown in the figure. As a result, a step operation is performed by a known operation, and if we look at the flow of magnetic flux in state a of the pulse train in FIG. 12 in response to the explanation of the conventional example, it becomes as indicated by the thin line arrow in FIG. 6. As is clear from comparing FIGS. 8 and 11, since the magnetic flux flows through the magnetic body 3,
It can be seen that the magnetic paths are separated and independent for each stator 7.8.

According to this embodiment, the rotor 4 has a pair of permanent magnets 1,
Since the disk-shaped magnetic body 3 is interposed between the permanent magnets 2 and the permanent magnets 2 are overlapped with each other, the mechanical strength of the permanent magnets 1 and 2 can be improved. In addition, since a part of the magnetic circuit of each stator 7.8 is composed of the magnetic body 3 and is separated for each stator 7.8, the magnetic path is shortened, thereby improving characteristics such as magnetic efficiency and angular accuracy. I can do it.

[Effects of the Invention] According to the step motor of the present invention, since the rotor has a pair of permanent magnets that are overlapped with a disc-shaped magnetic material interposed between them, a part of the magnetic circuit of each stator is made of magnetic material. The stator is separated for each stator, and the magnetic path is shortened. Therefore, there is an effect that characteristics such as magnetic efficiency and angular accuracy and mechanical strength of the permanent magnet can be improved.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of one embodiment of the present invention, FIG. 2 is an overall sectional view, FIG. 3 is a partially omitted plan view of the stator, and FIG.
The figure is a side view showing the laminated state of the permanent magnets of the rotor, FIG. 5 is a cross-sectional view of the excitation coil, FIG. 9 is a plan view of the permanent magnet, FIG. 10 is a partial side view thereof, FIG. 11 is an explanatory diagram showing the flow of magnetic flux, and FIG. 12 is a waveform of the voltage applied to the excitation coil. It is a diagram. 1.2... Permanent magnet, 3... Magnetic material, 4... Rotor, 5... Internal teeth, 6... External teeth, 7, 8... Stator, 9, 10... Exciting coil, N, S...Magnetic pole 1, 2-m integrated magnet 3-Garden body 4...Rotor Fig. 2 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 D1 ゝ---' a Figure 11 PITirFa"1

Claims (1)

[Claims] A pair of disk-shaped permanent magnets formed such that a plurality of magnetic poles magnetized in the axial direction alternately become different magnetic poles in the circumferential direction are opposed in the axial direction so that the different magnetic poles face each other, and the pair of a rotor that is superimposed with a disc-shaped magnetic body interposed between permanent magnets; internal teeth that are arranged on both sides of the pair of permanent magnets in the axial direction and project radially outward; External teeth protruding inwardly from the outer circumferential side are opposed to each other in substantially the same plane so that the same magnetic poles in the circumferential direction of the permanent magnet are shifted by π from each other with 1 electrical angle, and A step motor comprising a pair of stators circumferentially shifted from each other by π/2 of the electrical angle on both sides, and excitation coils that respectively excite these stators.