JPH0136341B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stepping motor, and particularly to a stepping motor that has a short axial length and is capable of operating at minute step angles.

The stepping motor of the present invention includes a cylindrical permanent magnet magnetized in a direction parallel to the rotor axis, and a pair of pole pieces each having a large number of pole teeth formed at equal pitches on the outer circumferential surface of the cylindrical permanent magnet fixed to both ends thereof. and a stator consisting of four magnetic poles and two stator windings arranged oppositely on the outer periphery of the rotor with an air gap in between, and each magnetic pole of the stator is connected to the rotor shaft. an annular disk perpendicular to the annular disk, a short cylinder having an inner diameter larger than the outer diameter of the rotor by the gap length and extending in the axial direction from the inner peripheral surface of the annular disk; It consists of a stator core having the same number of pole teeth as the pole teeth of the rotor, which are formed in a pitched manner, and each set of two stator cores is arranged with their short cylindrical end faces facing each other with a gap interposed therebetween. The stator winding is wound around the outer periphery of the opposed short cylinders, and the stator cores of each set are coaxially coupled by a magnetic yoke.

Referring to the drawings, conventional stepping motors are shown in FIGS. 6 and 7, and embodiments of the stepping motor of the present invention are shown in FIGS. 1 to 5.

FIG. 6 is an explanatory diagram of a conventional stepping motor, in which 61 is a stator core, 62 is a rotor permanent magnet, 63 is a rotor shaft, and 64 is an air gap between the stator core 61 and the rotor. , 65 is a stator winding, 66 is a stator housing, 67 is an end bracket, 68 is a bearing of the rotor shaft 63, and A and B are pole pieces provided at both ends of the permanent magnet 62 of the rotor, respectively.

The stator core 61 has eight magnetic poles 61-1 to 61-8 as shown in FIG. are provided with pole teeth of the same pitch as the pole teeth provided on the outer circumferential surfaces of the pole pieces A, B, and are disposed opposite to the pole teeth of the pole pieces A, B with a gap 64 interposed therebetween.

The stator windings 65- are attached to the magnetic poles 61-1 to 61-8.
1 to 65-8 are provided, respectively, and the windings located at point-symmetrical positions about the rotor shaft 63 are connected to form a set to constitute a four-phase winding.

The number of pole teeth on the outer circumference of pole pieces A and B is the same, and the arrangement of the pole teeth of pole pieces A and B is 1/2 of each other.
It is said that the position was moved a little.

In the stepping motor shown in FIG. 6, by sequentially energizing the four phases of the stator winding 65, the rotor steps at an angle corresponding to 1/4 pitch of its pole teeth. Therefore, by making this step angle smaller, the disassembly accuracy of the stepping motor can be increased, and by attaching pole pieces A and B with pole teeth to the permanent magnet 62 as shown in FIG. Due to production technology, the pole teeth can be made extremely fine.

However, in the configuration shown in Figure 6, it is necessary to wind each winding around each of the eight magnetic poles of the stator core, and to connect each winding end to separate each winding into four-phase groups, which requires many steps. and requires skilled manpower. In addition, the portion of each winding that overhangs the stator core 61 extends in the axial direction, and it is necessary to provide a gap between it and the end bracket 67 for maintaining insulation. There are drawbacks such as the need to lengthen only certain parts.

Another type of stepping motor is No. 7.
There is a configuration shown in the figure. 7 in Figure 7
1 and 72 are flat stator windings wound around the stator core 73 around the rotor shaft 75, 74 is a cylindrical permanent magnet, 76 is a rotor hub, and 77 and 78 are bearings for the rotor shaft 75. , 79 is the outer cover of the electric motor.
As shown in FIG. 7b, the stator core 73 of the stepping motor having the configuration shown in FIG. The bearings 77, 7
It is housed in a jacket 79 with 8. Further, the cylindrical permanent magnet 74 forming the rotor is attached to the rotor hub 7.
The cylindrical permanent magnet 74 is integrally fixed to the rotor shaft 75 via the magnet 6, and the cylindrical permanent magnet 74 is alternately magnetized with N poles and S poles in the circumferential direction.
-1, 73-2 are opposed to each other through a gap.
In the stepping motor with the configuration shown in Fig. 7,
As for the winding, only two flat windings are provided around the outer circumference of the magnetic pole, and there is no need for complicated connections between the windings as in the stepping motor shown in Figure 6, and there is no protrusion at the ends of the windings, so the shaft Although there is an advantage that the length in the direction can be shortened, the magnetic poles 73-1, 73- of the stator core are
2 is formed by cutting and raising a disc-shaped thin plate, it is not possible to form a pole that is thinner than a certain extent due to the manufacturing technology and the strength of the product. Furthermore, since the rotor magnetic poles are formed by directly magnetizing the outer periphery of the cylindrical permanent magnet 74, increasing the number of poles has disadvantages such as an increase in leakage magnetic flux between adjacent magnetic poles and a decrease in magnet usage efficiency. It is not possible to obtain a step angle as fine as that of the stepping motor shown in FIG. 6.

The stepping motor of the present invention is shown in FIGS. 6 and 7.
The present invention provides a stepping motor that is short in the axial direction and operates at a fine step angle by taking advantage of the advantages of the conventional stepping motors shown in the drawings and eliminating their disadvantages.

In Fig. 1, 1 is an end bracket, 2 is a motor jacket that also serves as a yoke, 3, 4, 5, and 6 are stator cores, 7 and 8 are stator cores, 9 is a bearing, 10 is a rotor shaft, and 11 is a stator core. The rotor hub, 12 and 14 are rotor pole pieces, and 13 is a permanent magnet.

In the stepping motor of the present invention, a bearing 9 is fixed to the center of an end bracket 1, a stator core 3 is fixed concentrically to the end bracket 1, and a stator core 6 and a stator winding are fixed to the inside of the motor jacket 2. The stator part, in which the wires 8, stator cores 5 and 4, and stator winding 7 are attached in this order, is firmly fixed to the end bracket 1 using the inner circumferential surface of the motor jacket 2 and the outer circumferential surface of the stator core 3 as guides. Complete the child. The insulation between the stator windings 7, 8 and the stator cores 3, 4, 5, 6 may be achieved by winding the windings around a winding frame made of an insulating material, or by winding the windings around a winding frame made of an insulating material. Means such as interposing a thin insulator between the child winding and the stator core, or applying an insulating paint to the surface of the stator core may be used, and the selection thereof is free.

As shown in FIG. 2, the stator core 3 in the stepping motor of the present invention has a short cylinder 3-1 protruding at right angles from the inner periphery of an annular disk made of a magnetic material. It is formed by arranging pole teeth 3-2 at equal pitches on the surface. The pitch of the pole teeth 3-2 is the same as the pitch of the teeth of the pole pieces 12 and 14 provided on the rotor. All of the stator cores 4, 5, and 6 also have the same shape as the stator core 3.

As shown in FIG. 3, the rotor of the stepping motor of the present invention has a permanent magnet 13 attached to the outer periphery of a hollow rotor hub 11, and pole pieces 12 and 14 in contact with both axial end surfaces of the permanent magnet 13. one end surface of the rotor hub 11 is connected to the rotor shaft 10.
sticks to.

Furthermore, pole teeth 12-1 and 14-1 are formed on the outer peripheral surfaces of the pole pieces 12 and 14, respectively, at equal pitches and spaced apart from each other, and the pole teeth 12-1 and 14-1 are formed as shown in FIG. 4b. so that they are aligned on the same line parallel to the axis.

On the other hand, the pole teeth of the stator cores 3, 4, 5, and 6 of the stepping motor of the present invention are 1/2 of the pole pitch P between the stator cores 3 and 4, as shown in FIG. and 5, 1/4P, stator core 5 and 6
Place them at an angle of 1/2P between them.

The operation of the stepping motor according to the present invention is explained in the fifth section.
The explanation will be as follows using the developed view shown in the figure.

In the present invention, the terminals a, b of the stator winding 7,
An energization control device (not shown) is installed so that the excitation current flows through terminals c and terminals d, e, and f of stator winding 8 as terminals a-b→, c-b→, d-e→, and f-e→. ) to connect to the power supply. Figure 5 shows terminals a-b → energized and stator pole tooth 3-.
2 and the pole teeth 12-1 of the rotor pole piece 12 are shown aligned. Next, when the terminal f-e → is energized and the current is stopped at a-b →, the stator pole tooth 6-2 and the rotor pole tooth 14-1 are attracted and the rotor moves to the right in the direction of the arrow. The pole teeth 6-2 and 14-1 are aligned and rotated by an angle corresponding to 1/4 of the pole pitch P.
This angle is one step angle. Next, to move in the same direction, energize the terminal c-b→ and stop the current at f-e→, the pole tooth 4-2 and the pole tooth 12-1 are aligned and further 1
Take a step forward. Next, when terminal d-e→ and flow stop c-b, it moves one step further to the right. To reverse the stepping direction, the order of energization switching may be reversed.

The structural advantages of the stepping motor according to the present invention detailed above are compared with the stepping motor according to the prior art as follows. In other words, the stepping motor with the configuration shown in Figure 6 has eight windings, and the number of pole teeth provided on the rotor is determined by the number of pole teeth provided on the rotor per pole piece.
In a configuration with 50 pieces, one step angle is 1.8 degrees.
Further, the number of pole teeth of the stator of the stepping motor having the configuration shown in FIG. 7 is limited to 24, and the smallest angle of one step is 7.5 degrees. In contrast, in the present invention, the number of pole teeth provided on the rotor pole piece is 50, the number of windings is 2, and the angle of one step is 1.8.
It can be made into degrees and minute angles.

Furthermore, in the stepping motor of the present invention, the stator core has a short cylinder protruding from the inner peripheral part of the annular disk, and a part of the inner peripheral surface of the short cylinder protrudes in the radial direction. Since the pole teeth are not independent, the rigidity is strong and a large number of pole teeth can be easily provided. In addition, when the stator cores 3, 4, 5, and 6 are combined, the end surfaces of the short cylinders of the stator cores 3 and 4 and 5 and 6 face each other with a gap g interposed between them, and this gap g is the space between the stator cores. This leakage magnetic flux becomes a path for magnetic pole 7.
The number of magnetic poles 3-1 and 73-2 is smaller than that of the conventional stepping motor shown in FIG. 7, which alternately protrudes, so although the axial length of the magnetic poles is short, there is a large amount of effectively interlinked magnetic flux, resulting in high efficiency.

Furthermore, since the magnetic poles of the stator have high rigidity, the inner circumferential surface thereof has good circularity, and the gap length with the rotor can be shortened, resulting in higher efficiency than the one shown in FIG.

Further, in the rotor of the stepping motor of the present invention, the rotor shaft is fixed to one end of the hollow rotor hub 11 with an inner diameter larger than the outer diameter of the bearing 9, so that the rotor has a cantilevered structure with one bearing 9. The length in the axial direction can be shortened.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a stepping motor according to the present invention, FIGS. 2a and 2b are a sectional view and a side view of a stator core, respectively, FIG. 3 is a perspective view of a rotor, and FIGS.
b is a partial exploded view showing the arrangement of the pole teeth facing the gaps between the stator and rotor, respectively; FIG. Figures 6a to 6d are a vertical front view, a vertical side view, and a vertical side view of a conventional stepping motor, respectively.
A cross-sectional view taken along the line X--X of FIG. 6, a cross-sectional view taken along the Y-Y line of FIG. 1...End bracket, 2...Motor jacket,
3, 4, 5, 6... Stator core, 7, 8... Stator winding, 9... Bearing, 10... Rotor shaft, 11...
...Rotor hub, 12, 14...Pole piece, 1
3...Permanent magnet, 3-1...Short cylinder, 3-2, 4
-2,6-2,12-1,14-1...Polar teeth.

Claims (1)

[Claims] 1. A rotor consisting of a cylindrical permanent magnet magnetized in a direction parallel to the rotor axis and a pair of pole pieces fixed to both ends of the pole piece, each having a large number of pole teeth formed at equal pitches on its outer circumferential surface, and this rotation. The stator has a stator consisting of four magnetic poles and two stator windings arranged opposite to each other with an air gap on the outer periphery of the child, and each magnetic pole of the stator has an annular disk perpendicular to the rotor axis. , a short cylinder having an inner diameter larger than the outer diameter of the rotor by the gap length, and protruding in the axial direction from the inner peripheral surface of the annular disk;
It consists of a stator core having the same number of pole teeth as the pole teeth of the rotor, which are formed at equal pitches on the inner circumferential surface of this short cylinder. The stator windings are wound around the outer periphery of the opposed short cylinders, and the stator cores of each set are coaxially coupled by a magnetic yoke. A stepping motor featuring: