JPH03203566A - Stepping motor - Google Patents

Abstract

PURPOSE:To facilitate the assembly and to prevent breakdown by forming one end each of a plurality of bar-shaped permanent magnets, which are to be inserted in the grooves between the plurality of pole teeth of a pair of rotor iron cores whose phases are deviated by 1/2 pitches and are magnetized in diameter direction, into a disc part. CONSTITUTION:A plurality of rotor tooth 18 formed at the peripheries of a pair of rotor iron cores 16a and 16b are made with the phases slid by 1/2 pitches. One end each of a plurality of bar-shaped permanent magnets 22 magnetized in diameter direction are connected into a disc part 22A consisting of a magnetic body to form a circular magnet body 22b, and the bar-shaped permanent magnets 22 are inserted in the grooves between the rotor teeth 18. A disclike permanent magnet 14 is held between the rotor iron cores 16a and 16b with which magnet bodies 22B are engaged, and a rotary shaft 12 is inserted to form a rotor 10. Hereby, the assembling work of the rotors of a hybrid type stepping motor is performed easily, and the breakdown of bar-shaped permanent magnets is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hybrid stepping motor in which a rod-shaped permanent magnet is fixed between rotor teeth and between stake teeth to increase torque.

(Prior art) There is a demand for the development of a small and lightweight motor, that is, a motor with high output density (motor torque/motor weight), as an actuator for the drive mechanism of precision control equipment for OA, FA, etc. .

Conventionally, hybrid stepping motors have been widely used as such actuators. In this motor, a disk-shaped permanent magnet magnetized in the axial direction is sandwiched between a pair of rotor cores, and rotor teeth are formed on each rotor core with a phase shift of 1/2 pitch to periodically excite the stator magnetic poles. This is what I did. This type of motor has a large number of teeth (inductors) on the surface (gap surface) that faces the air gap between the rotor core and stator pole, so the air gap magnetic flux density changes as the magnetic resistance changes depending on the rotor position. . Therefore, the magnetic energy changes and torque is generated. In this case, in order to increase the output density of the motor, it is conceivable to narrow the air gap length or increase the magnetic loading and electrical loading. However, if this is done, the problem arises that the iron core tooth portion becomes magnetically saturated and magnetic flux leaks to the tooth side surface, making it difficult to increase the torque and increasing the size of the motor.

Therefore, the applicant proposed fixing rod-shaped permanent magnets in the grooves between the teeth of the rotor and between the teeth of the stake. This is because the main magnetic flux generated on the surface of the rotor core by the disk-shaped permanent magnet is canceled by the rod-shaped permanent magnet magnetized in the radial direction, and the leakage magnetic flux to the tooth groove bottom and tooth side is forcibly suppressed. It is.

Figures 4 to 7 show this previously proposed motor. That is, Fig. 4 is a radial cross-sectional view, Fig. 5 is an axial cross-sectional view, Figs. 6A and 6B are developed views of the magnetic poles taken along the lines A-A and B-B in Fig. 5, and Fig. 7 is a cross-sectional view of the magnetic poles. It is a perspective view of a rotor.

In these figures, the reference numeral 10 is a rotor, which includes a rotor shaft 12, a disk-shaped permanent magnet 14, and a pair of rotor cores 16 (16
a, 16b), and rod-shaped permanent magnets 22 (22a, 22b) fixed between the rotor teeth 18 (18a, 18b) formed on the outer peripheral surface of both rotor cores 6. The disk-shaped permanent magnet 14 is magnetized in the axial direction as shown in FIG. 6, and the rotor teeth 18a and 18b of each rotor core 16 are as shown in FIG. 6A and FIG. 6B. The phase is shifted by 1/2 pitch. The rod-shaped permanent magnet 22 is magnetized in the radial direction, and its polarity is in a direction that cancels out the main magnetic flux produced by the disk-shaped permanent magnet 14.

24 is a stake, and each rotor core 16a, 16 is provided on the inner circumferential surface of the stake pole 26 protruding at equal intervals in the circumferential direction.
axial stator teeth 28 (28a, 28
b) is formed, and rod-shaped permanent magnets 32 (32a, 32b) are fixed in the grooves between the stator teeth 28. Here, the rod-shaped permanent magnets 32 are magnetized to have the same polarity in the radial direction as the rod-shaped permanent magnets 22a, 22b of the respective rotor cores 16a, 16b. 34 is a winding wound around each stator pole 26.

In previously proposed motors having such a configuration, the rod-shaped permanent magnets 22 are inserted one by one into the rotor grooves 20a and fixed with adhesive, as shown in FIG. The rod-shaped permanent magnets 32 on the stator 24 side were also adhesively fixed one by one in exactly the same way.

However, the width and thickness of the rod-shaped permanent magnet 22 of the rotor are 0.5~
Since it is quite small at about 2 mm and easily damaged by impact, there has been a problem that the yield of fixing it is low. In particular, when attaching a pre-magnetized bar-shaped permanent magnet 22 to the rotor 10, since the polarity of the bar-shaped permanent magnet 22 is opposite to that of the disk-shaped permanent magnet 14, it receives a repulsive force when inserted, resulting in poor workability. This makes the magnet 22 more likely to be damaged.

(Objective of the Invention) The present invention has been made in view of the above circumstances, and has good workability when attaching a bar-shaped permanent magnet between rotor teeth.
Another object of the present invention is to provide a stepping motor in which the rod-shaped permanent magnet is less likely to be damaged.

(Structure of the Invention) According to the present invention, this object is achieved by forming rotor teeth that are shifted in phase by 1/2 pitch from each other on each of a pair of rotor cores that sandwich a disc-shaped permanent magnet that is magnetized in the axial direction; In a hybrid stepping motor in which radially magnetized rod-shaped permanent magnets are fixed in the grooves between the rotor teeth and the stator teeth, all the rod-shaped permanent magnets installed between the rotor teeth,
A magnet body is formed by integrally molding a disk portion to which one end of the rod-shaped permanent magnet is coupled, and the rod-shaped permanent magnet is inserted between the rotor teeth from the axial direction so that the magnet body is attached to the rotor core. This is achieved by a stepping motor which is characterized by being fixed.

(Example) Fig. 1 is a perspective view showing a rotor core and magnet body according to the present invention, Figs. 2A and 2B are axial cross-sectional views showing two embodiments of the assembled state of the rotor, FIG. 3 is a diagram showing a magnetizing device for a magnet body.

The rod-shaped permanent magnets 22 that fit between all the rotor teeth 22 of one rotor core 16 are connected at one end by a disk portion 22A, and these rod-shaped permanent magnets 22 and the disk portion 22A form a magnet body 22B. has been done.

This magnet body 22B is made using a molding machine 100 shown in FIG. 3, for example. In this case, the magnet body 22B is made of rare earth magnetic material. Rare earth magnetic materials are made by molding a clay-like fluid material into a predetermined shape and then sintering it. In this embodiment, this clay-like material is placed between a pair of upper and lower press molds 102, 104 and pressed to form a magnet body 22B having the shape shown in FIG. Here, each press mold 102.104 has a coil 106.108.
are wound and, during the press forming process, before the material hardens, current is passed through these coils 106, 108, creating a magnetic flux as shown by the dashed lines in FIG. As a result, magnet body 2
Magnetic anisotropy is imparted to the rod-shaped permanent magnet portion 22 of 2B in the radial direction, and magnetic anisotropy is imparted to the disk portion 22A in the axial direction. Note that when aligning the open end of each rod-shaped permanent magnet 22 from one end of the rotor teeth 18 to the groove between the rotor teeth 18 and pushing it into the groove, an adhesive is applied in the groove. Similarly, magnet body 122B
is also molded.

The magnet bodies 22B, 122B formed in this way are
As shown in the figure, it is fitted into the rotor core 16 and magnetized in this assembled state. That is, the magnets 22B, 122B are attached by being sandwiched between the magnetic poles surrounding the outer periphery and the outer surface of the disk portion of the magnets 22B, 122B and the magnetic pole contacting the end surface of the rotor core 16, and passing magnetic flux between the two magnetic poles. be magnetized.

After being magnetized in this way, these are shown in Figure 2A or 2B.
It is assembled as shown in the figure. The one in Figure 2A is the magnet body 2
2B from the opposite side of the disk-shaped permanent magnet 14 to the rotor core 16.
It was installed on. In addition, two preliminary assemblies were prepared in which the magnet body 22B was attached to the rotor core 16 as shown in FIG. It is something.

Although the magnet body 22A is made of a rare earth magnetic material in the embodiment described above, it may be made of a normal metallic magnetic material such as alnico. Alternatively, the magnet may be formed by dispersing a metal magnetic substance in an elastic material such as a rubber magnet or a plastic magnet. In this case, the rod-shaped permanent magnet 32 is firmly fixed between the rotor teeth 18 by its own elasticity. It becomes possible.

(Effects of the Invention) As described above, the present invention integrates all the rod-shaped permanent magnets fixed between the rotor teeth to the periphery of the disc portion to form an integrated magnet body, which is Since it is fixed to the rotor core, the rod-shaped permanent magnet can be easily attached to the rotor side, and the rod-shaped permanent magnet is less likely to be damaged during the work, improving work efficiency.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a rotor core and a magnet body according to the present invention, FIGS. 2A and 2B are axial cross-sectional views showing two embodiments of the assembled state of the rotor, and FIG. 3 is a magnet body. FIG. 2 is a diagram showing a body magnetization device. 4 to 7 are diagrams showing the previously proposed motor. FIG. 4 is a radial sectional view thereof, FIG. 5 is an axial sectional view, and FIGS. B-
1 and 7 are perspective views of the rotor. O...Rotor, 4...Disc-shaped permanent magnet, 6...Rotor core, 8...Rotor tooth, 2...Bar-shaped permanent magnet, 2A...Disc part, 2B...Magnet body.

Claims (1)

[Claims] A pair of rotor cores sandwiching a disc-shaped permanent magnet magnetized in the axial direction are provided with rotor teeth that are 1/2 pitch out of phase with each other. In a hybrid stepping motor in which rod-shaped permanent magnets magnetized in the radial direction are fixed in grooves, all the rod-shaped permanent magnets installed between the rotor teeth are integrated with a disk portion to which one end of the rod-shaped permanent magnets is connected. What is claimed is: 1. A stepping motor comprising: a magnetic body formed by molding, the magnetic body being fixed to a rotor core by inserting the rod-shaped permanent magnet from the axial direction between the teeth of the rotor.