JPH07110124B2 - Step Motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a step motor.

BACKGROUND ART FIG. 6 to FIG. 12 show proposed examples. That is, the step motor includes a rotor 50 in which different magnetic poles are alternately magnetized in the circumferential direction and a plurality of magnetic pole teeth 51 facing the magnetic poles.
A pair of stator poles 52,5
3 and a stator 55 having a coil 54 wound around each of the stator magnetic poles 52 and 53.

This step motor is arranged such that the stator magnetic poles 52, 53 are displaced from each other in the circumferential direction by an electrical angle of π / 2, and the coils 54 of the stator magnetic poles 52, 53 have alternating currents of π / 2 phase offset from each other. When the current is supplied to the rotor 50, the rotor 50 performs a step operation by a known operation. That is, when the alternating current shown in FIG. 11 flows through each coil 54, the relationship between the magnetic pole teeth 51 and the magnetic poles N and S of the rotor 50 becomes as shown in FIG. First
1A shows the voltage waveform of the coil 54 of the stator magnetic pole 53, and FIG. 1B shows the voltage waveform of the coil 54 of the stator magnetic pole 52. During operation of the rotor 50, the magnetic pole teeth 51 and the magnetic poles N, S of the rotor 50 are
Face each other with the same polarity, and different polarities are located between the magnetic pole teeth 51.

However, in this step motor, when an undesired overcurrent flows through the coil 54, the magnetic poles 56 'of the rotor 50 located between the magnetic pole teeth 51 are demagnetized by the magnetic poles generated on the recess bottom surface 57 between the magnetic pole teeth 51. There was a drawback that I could receive it. As a result, the surface magnetic flux density of the rotor 50 becomes as shown in FIG. 12, and the portion 58 demagnetized by the demagnetization amount I is generated. Rotor
When the magnetic poles N and S of the 50 are demagnetized, characteristics such as angular position accuracy are affected.

[Object of the Invention]

An object of the present invention is to provide a step motor capable of preventing the rotor from being demagnetized even when an overcurrent flows.

[Disclosure of Invention]

The step motor of this invention has a rotor in which different magnetic poles are alternately magnetized in the circumferential direction, and a plurality of magnetic pole teeth facing the magnetic pole and arranged in the same direction as the circumferential direction of the rotor. A stator having a pair of stator magnetic poles extending in the same direction as each other and having both ends thereof held in an installed state, and a stator having a coil wound around each of the stator magnetic poles, wherein the stator magnetic poles are , A part of the flat plate is processed into a U-shaped cross section to form a protruding surface,
The magnetic pole teeth are formed by punching a plurality of slits on the protruding surface.

According to the configuration of the present invention, since both ends of the rod-shaped magnetic pole teeth arranged in the same direction are supported by the stator magnetic pole in a erected state, a pole of the coil is not generated between the magnetic pole teeth even when an overcurrent flows through the coil. It is possible to prevent the magnetization of the rotor from being demagnetized. In addition, the stator pole is formed by punching a part of a flat plate so that it has a U-shaped cross section to form a protruding surface, and the magnetic pole teeth are formed by punching out multiple slits in the protruding surface. Is easy to manufacture.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 5. That is, this stepper motor has a rotor 1 in which different magnetic poles are alternately magnetized in the circumferential direction, and a plurality of magnetic pole teeth 2 facing the magnetic poles and arranged in the same circumferential direction as the rotor 1. A stator 6 having a pair of stator magnetic poles 3 and 4 having both ends thereof erected in a rod-like shape extending in the same radial direction as that of FIG. 1 and a coil 5 wound around each of the stator magnetic poles 3 and 4. It has and.

The rotor 1 is a disk-shaped permanent magnet 7 having magnetic poles.
And a bush 8 that adheres and supports the central portion of the permanent magnet 7, and a shaft 9 that penetrates the bush 8. As shown in FIG. 5, the permanent magnet 7 is multi-pole magnetized at regular intervals so that the magnetic poles N and S are magnetized in the axial direction, that is, the plate thickness direction, and different polarities appear alternately in the circumferential direction of each surface. Has been done.

As shown in FIG. 3, the stator magnetic poles 3 and 4 are formed in a U-shaped cross section by pressing the stator 6 having a flat plate as an embodiment, and are formed in the same direction so as to form a ring shape as a whole. Four stator magnetic poles 3 and 4 are displaced from each other in the circumferential direction by an electrical angle of π / 2. A bearing support 11 is formed at the center of the stator 6 and a rising portion 17 is formed at the peripheral edge. A bearing 12 is supported by the bearing support portion 11.

As shown in FIG. 4, on the protruding surfaces of the stator magnetic poles 3 and 4,
By punching slits 13 at the same intervals as the above-mentioned constant intervals in the circumferential direction, rod-shaped magnetic pole teeth 2 extending in the radial direction are formed.

The coil 5 is wound around the stator magnetic poles 3 and 4, respectively.

The stator 6 is a cylindrically formed housing
14 is fitted and forms a part of the stator 6. That is, the inner peripheral surface of the housing 14 is joined to the rising portion 17 of the stator 6 so as to be magnetically and mechanically coupled. Housing 14
The bearing support 15 is formed in the center of the
16 are provided. The permanent magnet 17 on the bottom of the housing 14
The magnetic pole tooth 2 having the same structure as the magnetic pole tooth 2 has a protruding amount smaller than that of the stator magnetic poles 3 and 4 at a portion opposed to the stator magnetic poles 3 and 4 via.
The stator magnetic poles 3a and 4a having a are formed so as to face each other.

Assemble the rotor 1 before covering the housing 14 on the stator 6.
One end of bush 8 is passed through one end of shaft 9
Then, the bearing 15 of the housing 14 is passed through the shaft 9 to project the shaft 9, and the housing 14 is fitted and joined to the stator 6. At this time, the multi-end surface of the bush 8 is supported by the bearing 16. 10 is a cover.

This stepping motor has a magnetic pole tooth 2, 2a of a stator magnetic pole 3, 3a or a stator as shown in FIG. 5 by an attraction force by the magnetic poles N, S of the permanent magnet 7 of the rotor 1 when no alternating current flows through the coil 5. Face the magnetic pole teeth 2, 2a of the magnetic poles 4, 4a. When the same alternating current as in FIG. 11 with a phase difference of π / 2 from each other is applied to the coil 5, magnetic flux is generated, for example, magnetic pole tooth 2 → permanent magnet 7 → magnetic pole tooth 2a →
Stator magnetic pole 3a → housing 14 → rising portion 17 → stator 6
→ Flows in the path of the stator magnetic poles 3 (the same applies to the stator magnetic poles 4 and 4a), and the rotor 1 performs a stepwise operation by an electric angle of π / 2 in a known operation.

When an overcurrent flows through the coil 5, a slit 13 is formed between the magnetic pole teeth 2 as shown in FIG. 5, and since there is no concave bottom surface 57 as in the proposed example, a pole due to the excitation of the coil 5 is not formed and the slit is formed. The magnetic pole 18 of the rotor 1 facing 13 is never demagnetized.

According to this embodiment, since both ends of the rod-shaped magnetic pole teeth 2 arranged in the same direction are supported by the stator magnetic poles 3 and 4 in a mounted state, even if an overcurrent flows in the coil 5, the coil 5 is provided between the magnetic pole teeth 2. Since no poles are generated, it is possible to prevent the magnetization of the rotor 1 from being demagnetized. Further, the stator magnetic poles 3 and 4 are formed by pressing a part of a flat plate to have a U-shaped cross section to form a protruding surface, and the magnetic pole teeth 2 are formed by punching out a plurality of slits 13 on the protruding surface. Therefore, the stator magnetic poles 3 and 4 can be easily manufactured.

Although the magnetic pole teeth 2a are formed on the housing 14 side in the above embodiment, they may be omitted in the present invention.

〔The invention's effect〕

According to the step motor of the present invention, since both ends of the rod-shaped magnetic pole teeth arranged in the circumferential direction are supported by the stator magnetic poles in a erected state, a pole of the coil is not generated between the magnetic pole teeth even when an overcurrent flows through the coil. Therefore, it is possible to prevent the magnetization of the rotor from being demagnetized. In addition, the stator poles are formed by punching out a part of the flat plate so that it has a U-shaped cross section to form protruding faces, and the magnetic pole teeth are formed by punching out multiple slits in the protruding faces. There is an effect that the magnetic pole can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of the present invention, FIG. 2 is a cross-sectional view of the stator poles taken along a cutting line in the circumferential direction, a perspective view of a third punched stator, and FIG. 4 is a magnetic pole. Partial perspective view showing details of teeth, FIG. 5 is a partially enlarged sectional view, FIG. 6 is a sectional view of a proposed example, and FIG. 7 is a sectional view of a state in which a stator magnetic pole is cut along a cutting line in the circumferential direction. 8 is a partial perspective view showing the details of the magnetic pole teeth, FIG. 9 is a partially enlarged sectional view, FIG. 10 is an explanatory view showing the relationship between the magnetic pole teeth and the magnetic poles of the rotor, FIG. 11 is a current waveform diagram of the coil, FIG. 12 is a characteristic diagram showing a state where demagnetization of the surface magnetic flux density in the circumferential direction of the rotor has occurred. 1 ... Rotor, 2 ... Magnetic pole teeth, 3, 4 ... Stator magnetic pole, 5
…… Coil, 6 …… Stator, 13 …… Slit

Claims (1)

[Claims] 1. A rotor in which different magnetic poles are alternately magnetized in the circumferential direction, and a plurality of magnetic pole teeth facing the magnetic pole and arranged in the same direction as the circumferential direction of the rotor are respectively in the radial direction of the rotor. A stator having a pair of stator magnetic poles extending in the same direction and holding both ends thereof in an installed state, and a stator having a coil wound around each stator magnetic pole, wherein the stator magnetic pole is a flat plate. Is a step motor in which a protruding surface is formed by subjecting part of the magnetic pole teeth to a U-shaped cross section, and the magnetic pole teeth are formed by punching a plurality of slits in the protruding surface.