JPS61132066A - Stepping motor - Google Patents

Abstract

PURPOSE:To reduce the size and to increase the torque of a stepping motor by bending a magnetic plate made of a plurality of legs extending radially from an annular base from the outside to form a core. CONSTITUTION:An A-phase stator is formed of a core body made of cores 23, 24 and a coil 25. A B-phase stator is formed of a core body made of cores 26, 27 and a coil 28. Cores 23, 24, 26, 27 are formed by bending a magnetic plate made of an annular base formed by punching and legs extending radially at an equal interval perpendicularly to the legs with respect to the base in a cup shape. The cores 23, 24, 26, 27 are concentrically disposed to form A-phase and B-phase core bodies to mount coils 25, 26 to form A-phase and B-phase stators.

Description

[Detailed description of the invention] (Industrial application field).

The present invention relates to a stepping motor that is compact but has high torque characteristics and high resolution characteristics.

(Prior Art) A stepping motor can accurately drive a load one step at a time, and is widely used as an output device for digital control equipment. In particular, with the development of small control devices such as floppy disk devices, the development of stepping motors that are compact and have high torque characteristics and high resolution characteristics has become an important issue.

Figures 6 to 9 show the configuration of a conventional stepping motor, with Figure 6 being an exploded perspective view, Figure 7 being a perspective view showing the structure of the first core, and Figure 8 showing the center of the rotating shaft. 9 is a sectional view taken along a plane perpendicular to the axis, and FIG. 9 is a sectional view taken along line 1-11 in FIG. 4. Permanent magnets 2 having north and south poles alternately magnetized in the circumferential direction are fixed to a rotating shaft 1 to constitute a rotor.

A stator having a human phase excitation section and a B phase excitation section is arranged around the rotor. The human phase excitation section is composed of first and second cores 3 and 4 for human phase excitation and a coil 5 for A phase excitation.
The first cores 3 and 6 of the O human body and the B phase, which are composed of cores 6 and 7 and a B-phase excitation coil 8, are each formed into a cylindrical part 3a that is formed by punching and drawing a steel plate and forming a yoke part. and 6a, and an integral number (six in the illustrated example) of magnetic pole pieces ab and 6b forming a magnetic pole part. In addition, the second cores 4 and 7 of the physiognomy and B soma are also formed by punching a steel plate, and have base parts 4a and 7a that contact the cylindrical parts 3a and 6a of the first core to form a magnetic path, and a rotor. It has an integral number (six in the illustrated example) of magnetic pole pieces 4b and 7b facing each other and forming a magnetic pole part. And the first and second core 3 for physiognomy
and 4, and the magnetic pole pieces ak), 4b, 6b, and 7b of the first and second legs 76 and 7 of the B soma are interlocked with each other and are mounted coaxially with respect to the central axis of the rotating shaft 1. There is.

The A-phase and B-phase coils 5 and 8 are composed of the cylindrical portions 3a and 6a of the first cores 3 and 6, and the magnetic pole pieces 3b and 6b, respectively.
◎The first cores 8 and 6 of the A phase and B soma are mounted in the space defined by the bracket 9, respectively.
and 10, and the second cores 4 and 7 are fixed back to back to each other and to the first cores 8 and 6, respectively. Furthermore, the brackets 9 and 10 have bearings 11.
and 12 are attached to rotatably support the rotating shaft 1. When excitation current is sequentially supplied to the human phase and B phase filters 5 and 8, magnetic flux is sequentially supplied to each magnetic pole piece, and the rotor rotates by l steps. In this case, let P be the magnetization pattern of the permanent magnet 2 constituting the rotor.
Since the human phase and B phase magnetic pole pieces are mounted offset from each other by 4, one step is equal to 4.

(Problem to be Solved by the Invention) The rotational torque of a stepping motor is approximately proportional to the length of the magnetic pole piece facing the permanent magnet, so in order to obtain high rotational torque, the length of the magnetic pole piece must be It is necessary to make the length as long as possible. However, in the above-mentioned conventional stepping motor, the steel plate is punched out and one end of each pole piece is connected to the inner peripheral edge of the ring-shaped yoke part and bent at right angles from the inside, so the pole pieces cannot be made longer. First, when trying to lengthen the magnetic pole piece, the outer diameter of the core becomes larger, resulting in an increase in the size of the motor itself.

Also, in order to obtain high resolution, the number of magnetic pole pieces must be increased. However, in the conventional stepping motor described above, the magnetic pole pieces are bent at right angles from the inside, so it is not possible to form a large number of magnetic pole pieces. Is it a drawback that the outer diameter has to be increased? Ta.

Furthermore, since the human-phase excitation part and the B-phase excitation part are arranged in a straight line, the motor itself has a vertically long structure along the central axis direction, which also has the disadvantage of increasing the size of the motor. (Means for Solving the Problems) An object of the present invention is to eliminate the above-mentioned drawbacks and provide a stepping motor that has high torque characteristics and high resolution characteristics without increasing the size of the core in both the radial and central directions. It is something.

The stepping motor according to the present invention includes a rotating shaft that transmits rotational torque, a permanent magnet coaxially connected to the rotating shaft and having S and N poles alternately magnetized in the circumferential direction, and the permanent magnet. , a core having a magnetic pole part and a yoke part arranged opposite to each other in the direction of the central axis thereof, and an excitation coil that generates a magnetic flux passing through the permanent magnet and the core. It has a cylindrical shape, and the outer and inner circumferential sides have N and S poles alternately along the circumferential direction so that the outer and inner circumferential sides have opposite polarities, and the core is parallel to the central axis. It consists of a cup-shaped core that integrally has a plurality of magnetic pole pieces extending concentrically and an annular yoke part whose outer periphery is connected to one end of these magnetic pole pieces, and two pieces with approximately equal diameters. A cup-shaped core body is constructed by arranging cup-shaped cores concentrically such that their open ends face in the same direction and each magnetic pole piece extends at least partially opposite to each other, and these cup-shaped cores An excitation coil is installed between them, and two cup-shaped core bodies with different diameters are arranged concentrically so that their open ends face in the same direction and the cylindrical permanent magnet is sandwiched between the magnetic poles of these core bodies. 0 (Function) In the present invention, a magnetic plate is punched out to form a magnetic plate consisting of an annular base and a plurality of legs extending radially from the outer periphery of the annular base. The portions are bent to form a cup-shaped core, and the legs serve as magnetic pole pieces facing the permanent magnet. And 2
A cup-shaped core body is constructed by concentrically arranging two cup-shaped cores with their open ends facing in the same direction and their magnetic pole pieces facing each other. The core bodies are human phase and B phase core bodies, and these human phase and B phase core bodies are arranged concentrically so that their respective open ends face the same direction and their respective magnetic pole pieces face each other. Then, a hollow cylindrical permanent magnet is magnetized alternately with S and N poles in the circumferential direction, and doubly magnetized in the radial direction so that the outer and inner circumferential sides have opposite polarities. A cylindrical permanent magnet is placed in a space where the magnetic pole pieces of the human phase and B phase core bodies face each other. With this configuration, it is possible to obtain a staping motor having high torque characteristics and high resolution without increasing the size in the central axis direction and radial direction.

(Example) Figures 1, 2, and 3 show the configuration of an example of a stepping motor according to the present invention. Figure 1 is an exploded perspective view, and Figure 2 is a plane perpendicular to the central axis. The cut cross-sectional view, FIG. 3, is If-1 [! of FIG. 2]. FIG. A hollow cylindrical permanent magnet 22 is connected to a rotating shaft 20 that transmits rotational torque via seven flange z1. This permanent magnet 22 has S poles and N poles alternately magnetized along the circumferential direction on the inner circumferential side and the outer circumferential side, respectively, and the outer circumferential side and the inner circumferential side have different polarities. Magnetize. A human-phase stator is housed in the inner periphery of this hollow cylindrical permanent magnet 22, and a B-phase stator is arranged in the outer periphery. B-phase stators are arranged concentrically. The A-phase and B-phase stators have almost the same structure except for their sizes, and the human stator has cup-shaped first and second cores 2.
The B-phase stator is composed of a core body consisting of cup-shaped first and second cores 26 and 27, and a coil 28. do. 6 first core 23 and 2
6 and the second cores 24 and 27 are each made of a magnetic plate consisting of an annular base made by punching and 6ffil legs extending radially at equal intervals, and each leg is made perpendicular to the annular base. The annular base is bent to form a cup shape, and each annular yoke Ws 23 a,
24 a.

26a and 27a, each leg extending parallel to the permanent magnet 22, 23k), 24b;

26b and z7b. The cup-shaped first cores 23 and 26 and the second cores 24 and 27 have the same diameter, and the lengths of the magnetic pole pieces 23b and 26b of the first core are the same.
The length of the coil 26 is longer than the length of the magnetic pole pieces 24b and 27b of the core.
and z8, respectively.

Then, the first cores 28 and 26 and the second cores 24 and 27
with each open end facing the same direction, each magnetic pole piece 23b
and z4b, z6b, and 27b are arranged concentrically with respect to the central axis line so as to face each other on the same circumference to constitute the human phase and B phase core body, and 1
Annular yoke portions 23a, 24 & 26 of the core and second core
Annular shaped coils 25 and 28 between a and 27 &
are installed respectively to form the A-phase and B-phase stators.

Then, these A-phase and B-phase stators are connected to permanent magnets 22.
When the magnetization pattern pitch of P is P, they are shifted by 2 and are mounted concentrically so that each open end faces the same direction.

Further, the A-phase and B-phase stators are attached to a bearing body 29 that rotatably supports the rotating shaft 20.

With this configuration, the magnetic circuit of the human phase excitation section is composed of the first core's magnetic pole piece 23b1 permanent magnet 22, and the magnetic circuit of the second B-phase excitation section is similarly composed of the first core's magnetic pole piece 26b1 permanent magnet 2.
2. The magnetic pole piece 27b1 of the second core is formed to pass through the annular yoke portion 2a of the second core and the annular yoke portion 26a of the first core. As a result, by alternately energizing the A phase and the B phase, the rotating shaft 20 rotates half a pitch at a time.

In this way, if the magnetic pole pieces of the human face and B-phase core bodies are arranged concentrically so as to face each other via a hollow cylindrical permanent magnet, the length in the central axis direction can be roughly halved. can be reduced.

FIG. 4 shows the configuration of a modified example of the stepping motor according to the present invention, and is a sectional view taken along a plane including the central axis. In other words, the rotating shaft 20 and the hollow cylindrical permanent magnet 22 are extended to approximately twice the length, and the rotating shaft 20 is integrally connected from above and below the central axis.
A cylindrical permanent magnet 2z is connected through a 7'7 pin 21, and two human phase/B phase stators are mounted through a bearing body 29. Then, the upper and lower A phase and B phase stators are arranged with different pitches. Now, the two stators on the lower side of the central axis are set as M1 and A2 phase, and the upper two stators are arranged as A2 phase. Bl, B2 phase, Al phase, B1 phase, A2
If the phase and the B2 phase are sequentially excited, the rotating shaft 20 will rotate sequentially by pitch. With this configuration, the resolution can be doubled.In addition, the hollow cylindrical permanent magnet can be supported on the rotating shaft at the center of gravity, and the permanent magnet and rotating shaft can rotate smoothly. (Effects of the Invention) The effects of the present invention explained above are summarized as follows. Because of this, the length of the magnetic pole pieces can be freely set without increasing the core diameter, making it possible to obtain a small stepping motor with high rotational torque, as well as making it easy to process and mold the core, reducing manufacturing costs. (2) Since the configuration is such that two cup-shaped core bodies with different diameters are arranged concentrically so as to face each other via a hollow cylindrical permanent magnet, the permanent magnet can be used effectively and the resolution and The length in the center axis direction can be almost halved without deteriorating the torque characteristics0 (3) Since the length in the center axis direction can be halved, 2
If the configuration is such that two stators are arranged concentrically so as to face each other via hollow cylindrical permanent magnets, and arranged above and below the central axis, the resolution can be doubled. I can◇・

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing the configuration of an example of a stepping motor according to the present invention, FIG. 2 is a sectional view taken along a plane perpendicular to the central axis of the stepping motor according to the present invention, and FIG. -11 Sectional view taken in the direction of the line, No. 4
Figure 5 is a sectional view showing the configuration of a modified example of the stepping motor according to the present invention, Figure 5 is an exploded perspective view showing the configuration of an example of a conventional stepping motor, and Figure 6 is the configuration of the first core of the conventional stepping motor. FIG. 7 is a cross-sectional view taken along a plane perpendicular to the central axis of a conventional stepping motor, and FIG. 8 is a cross-sectional view taken in the direction 1-1 of FIG. 7.・20...Rotation axis 21...7 Lange 12
2... Permanent magnets 23, 26... First cores 24, 27... Second cores 25, 28...
Coil 29...Bearing body Patent applicant Fpal Co., Ltd. Fig. 2 Fig. 3 zq (shaft-sea 2-4-)

Claims (1)

[Claims] 1. A rotating shaft that transmits rotational torque, a permanent magnet coaxially connected to the rotating shaft and having S and N poles alternately magnetized in the circumferential direction, and the permanent magnet. A stepping motor comprising a magnet, a core having a magnetic pole part and a yoke part arranged opposite to each other in the direction of the central axis thereof, and an excitation coil that generates a magnetic flux passing through the permanent magnet and the core, wherein the permanent magnet is It has a hollow cylindrical shape, and the outer and inner circumferential sides are alternately polarized with N and S poles along the circumferential direction so that the outer and inner circumferential sides have opposite polarities, and the core is aligned with the central axis. Consisting of a cup-shaped core integrally having a plurality of concentrically formed magnetic pole pieces extending parallel to the magnetic pole pieces and an annular yoke portion whose outer periphery is connected to one end of these magnetic pole pieces, and having approximately equal diameters 2 A cup-shaped core body is constructed by arranging a number of cup-shaped cores concentrically such that their open ends face in the same direction and each magnetic pole piece extends at least partially opposite to each other, and these cups An excitation coil is installed between the shaped cores, and two cup-shaped core bodies with different diameters are arranged concentrically so that each open end faces the same direction and the cylindrical permanent magnet is sandwiched between the magnetic poles of these core bodies. A stepping motor characterized by being arranged in.