JPH04128080U - Outer rotor stepping motor - Google Patents

Abstract

(57) [Summary] [Purpose] To increase the limit point where magnetic saturation occurs locally in the stator yoke to which the excitation coil is mounted, and to improve the rotational torque of the motor. [Structure] An inner yoke 5 made of a magnetic material that integrally has a plurality of flanges 5a on the outer periphery of a central cylindrical portion, a coil 8 wound in a groove-shaped portion between the flanges 5a of the inner yoke 5, and an outer periphery of the flange 5a. The stator is constituted by the outer yoke 6 which is tightly fitted and attached to the outer yoke 6. The wall thickness of the flange 5a is larger at the inner circumferential portion of the flange than at the outer circumferential side.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention relates to permanent magnet stepping motors, and is particularly applicable to the outer periphery of the stator. Improvement of outer rotor stepping motor with ring-shaped rotor magnets Regarding.

0002

[Conventional technology]

A stepping motor with a permanent magnet type claw pole structure has magnetic pole teeth due to its sheet metal structure. It constitutes a magnetic circuit surrounding the column and the excitation coil. This is a common inner rotor Not limited to the type of motor, for example, the outer The same applies to rotor type motors.

0003 In a conventional general claw pole stator, the magnetic pole tooth row for one phase is made of two sheets of metal. By attaching a large number of claws to the plate and aligning the claws of two sheet metal parts correctly facing each other. (referred to as a claw pole structure). And between those two sheet metal parts The coil wound on the bobbin is inserted between the two. In this structure, each stator part (sheet metal Air gaps in the magnetic pole tooth row may occur due to positioning errors when assembling parts (components) together. It is said that the angle is not uniform, and as a result, the static angle accuracy of the motor varies greatly. There was a problem.

0004 As a means to solve this problem, for example, Japanese Patent Laid-Open No. 61-135356 discloses As shown, slits are formed in one sheet metal part in the form of dashed lines. A technique is known in which magnetic pole tooth rows for two phases are formed on one sheet metal part by this method. According to this technique, the position and shape accuracy of the magnetic pole tooth row is extremely improved.

[0005] Adopting technology to form a magnetic pole tooth row using broken line slits in one sheet metal part, The present inventors previously proposed an outer rotor-type stepping motor with the structure shown in FIGS. 1 and 2. Developed a motor. First, regarding the previously proposed outer rotor type stepping motor. , will be explained in detail based on FIGS. 1 and 2.

[0006] 5 is an inner yoke, which integrally has three flanges 5a on the outer periphery of the central cylindrical portion. It is a magnetic material. Two grooves are formed on the outer periphery of the inner yoke 5 by three flanges 5a. A half-split bobbin 7 made of insulating material is set in each groove, and the A coil 8 is wound on top.

[0007] Reference numeral 6 denotes an outer yoke made of a ring-shaped magnetic material. A magnetic pole tooth row is formed by the slits 6a. The inner diameter of the outer yoke 6 is a flange. 5a, and as shown in the figure, there is a ring-shaped The outer yoke 6 is fitted in a tight fit.

[0008] 9 is a bearing fixed to the center hole of the inner yoke 5, and 3 is inserted through the bearing 9 and rotates. The rotor shaft is rotatably supported, and 15 is a retaining ring that stops the rotor shaft 3 from moving in the axial direction. , 1 is a cup-shaped rotor case fixed to the upper end of the rotor shaft 3, 2 is a cup The rotor magnet is a ring-shaped permanent magnet fixed to the inner peripheral surface of a shaped case 1.

[0009] The inner diameter of the rotor magnet 2 is slightly larger than the outer diameter of the outer yoke 6. The magnetic pole face faces the magnetic pole tooth row of the outer yoke 6 with a slight gap therebetween. In addition The magnetization pattern of the rotor magnet 2 and the pattern of the magnetic pole tooth row on the stator side are usually Since it may be the same as the permanent magnet type stepping motor, it will not be described in detail here.

0010 Further, 10 is a base plate fixed to one end surface of the inner yoke 5 with a screw 11. A terminal portion 14 for external connection is integrally formed on a part of the outer periphery. Be The base plate 10 is made of a metal plate, and the terminal part 14, which is thinner than other parts, is After forming an insulating layer on the surface, a wiring pattern 13 is formed by printed wiring on it. Ru. Then, the coil 8 The terminal end 12 is pulled out and soldered to the wiring pattern of the terminal portion 14. Na In Figure 1, 16 is a flat washer, 17 is a spring washer, and the rotor and stator This is to ensure smooth rotation of the rotor while eliminating the rotor.

[0011]

[Problem that the idea aims to solve]

The previously proposed outer rotor stepping motor shown in Figures 1 and 2 has multiple Rather than meshing protrusions on yoke parts to form a magnetic pole tooth row, Since the magnetic pole tooth row is formed on the yoke 6, the accuracy of the pattern of the magnetic pole tooth row depends on each part. It no longer depends on the assembly accuracy of the cylindrical part, and the plurality of flanges 5a can be aligned around the outer periphery of the central cylindrical part. Since the stator is constructed by combining the inner yoke 5 provided on the body and the outer yoke 6, Its basic features include a simplified structure and easy assembly. But figure The structure shown has the following problems that should be improved.

0012 In the outer rotor type stepping motor having the structure shown in FIGS. 1 and 2, the coil 8 If you try to increase the rotational torque of the motor by applying a large excitation current to the There was a limit for some reason. By passing an excitation current through the coil 8, the inner yoke 5 and the outer yoke are connected. A magnetic flux circulating through the yoke 6 is generated. Naturally, this magnetic flux is caused by the flange of the inner yoke 5. However, in the structure shown in Fig. 1, as the excitation current increases, the flange flows through the flange 5a. Magnetic saturation first occurs at the innermost circumference of gear 5a, and this causes an increase in motor torque. It is no longer possible to increase the effective magnetic flux that leads to increase.

[0013] The reason why magnetic saturation first occurs at the innermost peripheral part of the flange 5a is because of the magnetic path in this part. This is because the effective cross-sectional area (cross-sectional area in the direction perpendicular to the lines of magnetic force) is smaller than other parts. . The central cylindrical portion of the inner yoke 5 has a sufficient volume, and the effective cross-sectional area of the magnetic path is also large. hula The wall thickness of the hinge portion 5a is much smaller than that of the central cylindrical portion of the inner yoke 5, so the magnetic path is The effective cross-sectional area also becomes smaller. In particular, the volume of the flange 5a increases toward the outer periphery (circle (the circumference becomes longer), so the wall thickness of the flange 5a is uniform from the inner circumference to the outer circumference as shown in Figure 1. Therefore, the innermost peripheral portion of the flange 5a is the portion with the smallest effective cross-sectional area of the magnetic path. This is where magnetic saturation first occurs.

[0014] This idea was made in view of the conventional problems mentioned above, and its purpose is to The outer rotor type step pin with the basic structure shown in Figures 1 and 2 was proposed earlier by the inventors. For motors, raise the limit point at which magnetic saturation occurs in the stator yoke as much as possible. , the purpose is to make it possible to increase the motor torque.

[0015]

[Means to solve the problem]

Therefore, in this invention, a magnetic material having multiple flanges integrated around the outer periphery of the central cylindrical part is used. and a coil wound around the groove-shaped portion between the flanges of the inner yoke. ring-shaped with a magnetic pole tooth row formed by slits intermittent in the shape of broken lines. A magnetic sheet metal part that fits tightly around the outer periphery of the flange of the inner yoke. Outer rotor type stepping motor that consists of a stator with an attached outer yoke. At the same time, set the wall thickness of the flange of the inner yoke so that the inner peripheral part of the flange is Made it bigger.

[0016]

[Effect]

The inner circumference of the flange has a smaller circumference than the outer circumference, so the thickness of the flange should be the same. If they are the same, the effective cross-sectional area of the magnetic path will be smaller at the inner circumference. To compensate for this, Since the wall thickness of the inner periphery of the flange is larger than that of the outer periphery, the effective cross-sectional area of the magnetic path is almost uniform. As a result, the limit point at which magnetic saturation occurs locally increases.

[0017]

【Example】

Figures 3 and 4 show an outer rotor stepping motor improved by this invention. 2 shows the main configurations of two embodiments of the data processor. The basic configuration is as shown in Figures 1 and 2. It is the same as the proposed outer rotor type stepping motor, and there are multiple an inner yoke 5 made of a magnetic material that integrally has a flange 5a; A coil 8 wound in the groove-shaped portion between the flanges 5a and a slit 6 intermittent in the shape of a broken line Consisting of a ring-shaped magnetic sheet metal part having a magnetic pole tooth row formed by a, The outer yoke 6 is tightly fitted to the outer periphery of the flange 5a of the inner yoke 5, and the inner yoke A rotor shaft 3 rotatably supported through a bearing 9 in a center hole of a rotor shaft 5; A cup-shaped rotor case 1 fixed to the rotor case 1, and a rotor case 1 fixed to the inner peripheral surface of the case 1, and a ring-shaped rotor magnet 2 arranged around the outer periphery of the magnetic pole tooth row of the outer yoke 6. ing. The novel points different from the configurations of FIGS. 1 and 2 are as follows.

[0018] In the first embodiment shown in FIG. 3, the groove width between the flanges 5a of the inner yoke 5 is adjusted to the inner circumference. The cross section is shaped like a V-shaped valley, which is as small as possible, thereby reducing the thickness of the flange 5a. It is formed so that the thickness gradually decreases from the inner circumference to the outer circumference. Also in Figure 4 In the second embodiment shown, the groove-like portion between the flanges 5a has a cross-sectional shape almost like a U-shaped valley. As a result, the thickness of the innermost peripheral part of the flange 5a becomes larger than the other parts. That's what I do. In addition, when winding the coil 8 in the groove-shaped part between the flanges 5a, separate The bobbin 7 manufactured as an individual part may be used, or this bobbin 7 may be used instead of the bobbin 7. An insulating film may be formed on the groove-shaped portion using an appropriate plastic.

[0019]

[Effect of the idea]

As explained in detail above, in this design, the wall thickness of the inner yoke flange is The innermost part of the flange is larger than the outer part, so the inner part of the flange is larger than the outer part. The fact that the circumference is shorter than the outer circumference of the flange means that the wall thickness of the inner circumference of the flange is greater than that of the outer circumference. This cancels out the large difference in effective cross-sectional area of the magnetic path. As a result, The limit point at which local magnetic saturation occurs in the theta yoke increases, and the rotation of the motor increases. Torque can be improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an outer rotor type stepping motor, which is the premise of the present invention, which was previously proposed by the present inventors.

FIG. 2 is a partially cutaway perspective view of a stator assembly in the same motor.

FIG. 3 is a sectional view of a main part of a first embodiment in which the outer rotor type stepping motor described above is improved according to the present invention.

FIG. 4 is a sectional view of a main part of the second embodiment.

[Explanation of symbols]

1 Rotor case 2 Rotor magnet 3 Rotor shaft 5 Inner yoke 5a Flange 6 Outer yoke 6a Slit 7 Bobbin 8 coil

Claims (1)

[Scope of utility model registration request] 1. An inner yoke made of a magnetic material that integrally has a plurality of flanges on the outer periphery of a central cylindrical portion, a coil wound in a groove-shaped portion between the flanges of the inner yoke, and slits arranged intermittently in the shape of broken lines. an outer yoke that is tightly fitted and attached to the outer periphery of the flange of the inner yoke, and a bearing inserted into the center hole of the inner yoke. A rotor shaft rotatably supported by a rotor shaft, a rotor case fixed to the rotor shaft, and a ring-shaped rotor magnet fixed to the inner circumferential surface of the case and arranged around the outer circumference of the magnetic pole tooth row. An outer rotor type stepping motor, wherein the flange of the inner yoke has a wall thickness larger at an inner peripheral portion of the flange than at an outer peripheral side of the flange.