JPH0739130A - Stepping motor - Google Patents

Abstract

PURPOSE:To obtain a thin and face-to-face type PM stepping motor by positioning a pole tooth yoke assembly and a magnet so as to face each other and vertically to a rotary shaft. CONSTITUTION:A pole tooth yoke assembly is constituted of a first pole tooth yoke(YK) 4a, a second YK4b, and a third YK4c, each of which is magnetized in different polarity from each other and has a magnet pole tooth formed unevenly at a specified pitch in the radius direction from the center of rotation and formed as to surround the center of rotation. Non-magnetic sections 9 are formed between the magnet pole tooth of the YK4a and that of the YK4b and between the magnet pole tooth of the YK4b and that of the YK4c. A magnet 2 (rotor) and the pole tooth yoke assembly (stator) are so positioned as to face each other and vertically to a rotary shaft 1. By this method, a thin stepping motor can be obtained. Furthermore, as an outer diameter ratio of the magnet is large, large torque can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PM (permanent magnet) type stepping motor, and more particularly to a compact and high-performance thin stepping motor.

[0002]

2. Description of the Related Art FIG. 4 is a partial sectional view of an example of a conventional PM type stepping motor. FIG. 5 shows an extracted view of a conventional pole tooth yoke. In FIGS. 4 and 5, the rotor of the PM type stepping motor includes a rotating shaft 51, an N pole and an S on the outer circumference.
And magnets 52 having alternating poles. The rotor is rotatably supported by bearings 53a and 53b.

Two pole tooth yokes 54a and 54b having magnetic pole teeth magnetized to have different polarities and arranged so as to surround the rotor are regarded as one stator block.
Two sets of the stator blocks are arranged at an electrical angle of 90 ° to form one stator. One stator block is a single-phase motor, and two stator blocks are two.
Three phase motors operate as a three phase motor.

Here, an example of a two-phase motor will be described. The stator includes bobbins 55a and 55b in which four pole tooth yokes 54a to 54d are integrally molded with synthetic resin, and coils 56a and 56b wound around the bobbins 55a and 55b.
And a case 57. The bearings 53a and 53b are arranged at both ends of the case 57. Reference numeral 58 is a spring that is pressed against the tip of the rotating shaft to remove thrust backlash.

FIG. 6 is a plan development view of the conventional pole tooth yokes 54a to 54d and the magnet 52. In FIG. 6, the pole tooth yokes 54a to 54d and the magnet 52 are shown as X
By bending the surface including Z, the conventional cylindrical magnet 52 and pole tooth yokes 54a to 54d shown in the exploded perspective views of FIGS. 7A and 7B are obtained. As you can see from Figure 7,
The pole tooth yokes 54a to 54d are used by being stacked in the axial direction of the motor.

FIG. 8 shows the principle of rotation of the two-phase PM stepping motor from the magnetic path constituting surface. The magnetic flux returns to the magnet via the magnet → magnetic pole teeth → case → magnetic pole teeth. In the process of STEP1, STEP2, ..., The phase of the magnet with respect to the magnetic pole teeth sequentially moves, so that the magnet rotates. When the pole tooth yoke and the magnet shown in FIG. 8 are bent as described with reference to FIG. 6, a shape shown in FIG. 7 is obtained, which is used in the conventional PM type stepping motor described with reference to FIG.

[0007]

As described above, the conventional P
The pole teeth of the pole tooth yoke used in the M-type stepping motor are arranged in parallel with the axial direction of the magnet. This structure is suitable for a motor that is long in the axial direction, but if this structure is directly applied to a type that is short in the axial direction (thin type), it is disadvantageous in terms of strength and torque. The present invention has been proposed in view of such conventional problems, small size,
It is an object to provide a high-performance thin PM type stepping motor.

[0008]

A stepping motor according to a first aspect of the present invention is concentric with a pole tooth portion formed so as to surround the rotation center in a concavo-convex pattern at a predetermined pitch in a radial direction with respect to the rotation center. And a flat pole tooth yoke assembly having a non-magnetic portion between the pole tooth portions, and a flat pole magnetized with N and S poles at a predetermined pitch in the circumferential direction with respect to the center of rotation. And a pole magnet yoke assembly and the magnet are arranged perpendicular to the rotation axis so that their surfaces are opposed to each other. According to a second aspect of the present invention, in the stepping motor according to the first aspect, the nonmagnetic portion is filled with resin.
According to a third aspect of the present invention, in the stepping motor according to the first aspect, the pitches of the concavities and convexities of the respective pole tooth portions are the same, and the mutual phase of the pole teeth between the adjacent pole tooth portions is one of the tooth pitches. The feature is that they are shifted by / 4 minutes.

[0009]

As described above, by arranging the pole tooth yoke assembly (stator) and the magnet (rotor) perpendicularly to the rotating shaft so that their surfaces face each other, a compact and high-performance thin stepping motor is provided. It becomes possible to do.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the stepping motor of the present invention will be described below with reference to FIGS. 1 is a partial sectional view of an embodiment of the stepping motor of the present invention.
3A and 3B are plan development views of a pole tooth yoke and a magnet according to an embodiment of the present invention, and FIGS. 3A and 3B are front and side views of the magnet and pole tooth yoke assembly according to the embodiment of the present invention. Yes, FIG. 3 (A) is a diagram of the magnet, and FIG.
(B) is a figure of a pole tooth yoke assembly. Although the one embodiment will be described with an example of two phases, it is not limited to two phases. It goes without saying that it can be applied to a plurality of phases such as three phases and four phases.

FIG. 1 shows a partial sectional view of an embodiment of the stepping motor of the present invention. 1, a rotor of a stepping motor according to the present invention includes a rotating shaft 1 and a magnet 2 (N in FIG. 3) in which N poles and S poles are alternately formed on a plane (circumferential direction).
(See (A)). The rotor is rotatably supported by bearings 3. A back yoke 8 is arranged on the back surface of the magnet 2 and fixed to the rotary shaft 1.

A pole tooth yoke assembly is arranged face-to-face with the rotor. A front view and a side view of the pole tooth yoke assembly are shown in FIG. In FIG. 3 (B),
The pole tooth yoke assembly is magnetized to have different polarities and has a first pole tooth yoke 4a having magnetic pole teeth formed so as to surround the rotation center in a concavo-convex pattern at a predetermined pitch in the radial direction with respect to the rotation center. , The second pole tooth yoke 4b and the third pole tooth yoke 4c.

The magnetic pole teeth of the first pole tooth yoke 4a and the second pole tooth
The non-magnetic portion 9 is provided between the magnetic pole teeth of the pole tooth yoke 4b, and between the magnetic pole teeth of the second pole tooth yoke 4b and the third pole tooth yoke 4c. The non-magnetic portion 9 may be used as a pole tooth yoke assembly and outsert molded between the pole tooth yokes 4a to 4c. However, it is not limited to the outsert mold.

Returning to FIG. In FIG. 1, on the back surface of the pole tooth yoke assembly, there are arranged bobbins 5a, 5b having a U-shaped cross-section centering on the center of rotation. The bobbins 5a and 5b are made of iron which functions as a yoke, and the surfaces thereof are covered with an insulating layer. The bobbins 5a, 5b
The coils 6a and 6b are wound around the
The stator is covered with. The feature of the present invention resides in that the magnet 2 (rotor) and the pole tooth yoke assembly (stator) are arranged so as to be perpendicular to the rotating shaft 1 and face each other.

Next, the details of the pole tooth yoke assembly which is a feature of the present invention will be described. In FIG. 3, the first pole tooth yoke 4a has magnetic pole teeth on the inner circumference, the second pole tooth yoke 4b has magnetic pole teeth on the inner circumference and the outer circumference, and the third pole tooth yoke 4c has the outer circumference. It has magnetic pole teeth. First pole tooth yoke 4
The magnetic pole teeth on the inner circumference of a and the magnetic pole teeth on the outer circumference of the second pole tooth yoke 4b constitute a first-phase magnetic pole tooth group. Further, the magnetic pole teeth on the inner circumference of the second pole tooth yoke 4b and the third pole tooth yoke 4c
A second-phase magnetic pole tooth group is formed by the magnetic pole teeth on the outer periphery of the.

The first phase magnetic pole tooth group and the second phase magnetic pole tooth group are 1
/ 4 pitch (90 ° in electrical angle) is arranged,
It constitutes a two-phase stator. Although one embodiment has been described with an example of two phases, it goes without saying that, if the number of magnetic pole tooth groups is increased, a configuration of three phases or more is also possible, as described above. Further, the stepping motor has been described, but it can be applied to a frequency generator. In the case of a frequency generator, a single-phase configuration is possible.

To summarize the above description, the magnetic flux returns to the magnet via the magnet, the magnetic pole teeth, the bobbin, and the magnetic pole teeth. When both the pole tooth yoke and the magnet of the principle of rotation from the magnetic path constituting surface of the two-phase PM type stepping motor shown in FIG. 8 are bent in the plane including XY as shown in FIG. It becomes the shape of the magnet and pole tooth yoke assembly of A) and (B). A motor using this is the stepping motor according to the present invention in FIG. 1, which is thin and surface-opposed.

By adopting the face-to-face type, the magnetic attractive force obtained by this structure can be utilized, so that the spring for the purpose of stable rotation used in the conventional example becomes unnecessary.

[0019]

As described above, the PM according to the present invention
The type stepping motor has the following effects. 1) Since the magnetic pole tooth surface of the pole tooth yoke is parallel to the flat magnet surface and perpendicular to the rotation axis, a thin motor is possible. 2) A large torque can be produced because the outer diameter ratio of the magnet is large. 3) Since a magnetic attraction force can be used, a spring component is unnecessary. Moreover, the space related to this is unnecessary.

[Brief description of drawings]

FIG. 1 is a partial sectional view of an embodiment of a stepping motor of the present invention.

FIG. 2 is a plan development view of a pole tooth yoke and a magnet according to an embodiment of the present invention, FIG. 2A is a diagram of the pole tooth yoke, and FIG. 2B is a diagram of the magnet.

3A and 3B are a front view and a side view of a magnet and a pole tooth yoke assembly according to an embodiment of the present invention, FIG. 3A is a magnet diagram, and FIG. 3B is a pole tooth yoke assembly diagram.

FIG. 4 is a partial cross-sectional view of an example of a conventional PM type stepping motor.

FIG. 5 is an extraction view of a conventional pole tooth yoke.

6 is a plan development view of a conventional pole tooth yoke and magnet, FIG. 6A is a diagram of a pole tooth yoke, and FIG. 6B is a diagram of a magnet.

FIG. 7 is an exploded perspective view of a conventional cylindrical magnet and a pole tooth yoke, FIG. 7A is a magnet diagram, and FIG. 7B is a pole tooth yoke diagram.

8A is a principle diagram of rotation from a magnetic path forming surface of a two-phase PM type stepping motor, and FIG. 8B is a magnetic flux flow chart.

[Explanation of symbols]

 1 rotating shaft 2 magnet 3 bearing 4a first pole tooth yoke 4b second pole tooth yoke 4c third pole tooth yoke 5a, 5b bobbins 6a, 6b coil 7 case 8 back yoke 9 non-magnetic portion

Claims (3)

[Claims] 1. A plurality of concentric pole tooth portions formed so as to surround the rotation center in a concavo-convex pattern at a predetermined pitch in a radial direction with respect to the rotation center, and a non-magnetic portion between the pole tooth portions. A pole-shaped yoke assembly having a flat plate, and a flat magnet magnetized with N poles and S poles at a predetermined pitch in the circumferential direction with respect to the center of rotation, and the pole tooth yoke assembly and the magnet. A stepping motor characterized in that they are arranged perpendicular to the rotation axis so that their surfaces face each other. 2. The non-magnetic portion is filled with resin.
The stepping motor described in 1. 3. The pitch of the concavities and convexities of the respective pole tooth portions is made the same, and the mutual phase of the pole teeth between the adjacent pole tooth portions is shifted by ¼ of the tooth pitch. The stepping motor according to claim 1.