JPH05161334A - Stepping motor - Google Patents

Abstract

PURPOSE:To enable improvement of accuracy is assembly and the miniaturization by press stamping the pole tooth for the first phase and the pole tooth for the second phase into specified shapes out of a specified plate member by press processing, and then, bending them into cylindrical shape thereby uniting them. CONSTITUTION:For inner pole teeth 25, pole teeth 25A for A phases and pole teeth 25B for B phases are made to project in the shapes of trapezoid at both ends by press stamping a plate member 23 of iron material. Furthermore, the plate member 23 is bent into cylindrical shape, and then, the junction ends 25C and 25D are joined together, thus the pole teeth 25A and B for A phases and pole teeth 25B for B phases are made at the ends of both openings 26A and 26B of the cylinder. And the pole teeth 25A and 25B are positioned where the phases are shifted by the amount of a specified angle alpha each as an electric angle where one set of an S pole and an N pole of a rotor magnet is 360 deg., but the accuracy of the phase difference between pole teeth 25A and 25B is materialized by the accuracy in the stamping process by a press. Accordingly, a stepping motor can be gotten, wherein the phase difference between A phase and B phase can be improved exceptionally and the diameter becomes small.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Field of Industrial Application Conventional Technology (FIG. 10) Problem to be Solved by the Invention (FIGS. 10 and 11) Means for Solving the Problem (FIG. 1) Action (FIG. 1) Example (FIGS. 1 to 9) ) The invention's effect

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor, and is particularly suitable for application to a PM (permanent magnet) type stepping motor.

[0003]

2. Description of the Related Art Conventionally, as shown in FIG. 10, in a PM type stepping motor, pole teeth 5 and 6 are fitted from a side surface (a vertical direction in FIG. 10) of a coil bobbin 9 around which a coil 8 is wound. Then, the A-phase coil portion 3 is configured, and the pole teeth 11 and 12 are arranged from the side surface side (vertical direction in FIG. 10) of the coil bobbin 15 around which the coil 13 is wound in the same manner.
Is fitted to form the B coil portion 4.

As shown in FIG. 11, the A-phase coil portion 3 and the B-phase coil portion 4 have positioning protrusions 9A provided on the coil bobbin 9 for positioning the positioning holes 6A of the pole teeth 6 and the pole teeth 1.
No. 1 positioning hole 11B, and at the same time the positioning bobbin 15A provided on the coil bobbin 15 is inserted into the positioning hole 11A of the pole tooth 11 and the positioning hole 6B of the pole tooth 6 so that the pole tooth 6 and 11 target a predetermined electric angle (a pair of adjacent S and N poles of the S and N poles magnetized in the rotation direction of the rotor magnet is set as an electrical angle of 360 °) It is fixed in the displaced state.

The A-phase coil portion 3 and the B-phase coil portion 4 integrated in this way are connected to the outer yoke 16 (FIG. 10).
The rotor magnet 10 has a cylindrical shape and is housed in the inside of the coil portion 3 for A phase and the coil portion 4 for B phase.
And the rotary shaft 10A integrated with the rotor magnet 10 is engaged with the bearing 16A of the outer yoke 16.
Further, by fixing the bottom plate 18 to the end of the outer yoke 16 and engaging the bearing 18A of the bottom plate 18 with the rotating shaft 10A, the rotor magnet 10 is rotated by the outer yoke 16 and the bottom plate 18 via the rotating shaft 10A. Freely pivoted.

[0006]

However, in the stepping motor 1 having such a structure, the A-phase coil portion 3 and the B-phase coil portion 4 are separately formed, and the positioning protrusion 9A is assembled at the time of assembly. And 15A to adjust the phase difference between the A phase and the B phase to the target value (electrical angle 90 °). In this case, the positioning protrusions 9A and 15
There is a problem that the phase difference accuracy of the A phase and the B phase cannot be improved because the processing accuracy of A and the assembly accuracy at the time of phase matching are limited. Particularly, when the phase difference accuracy of the A phase and the B phase is deteriorated, there is a problem that so-called detent torque for holding the rotational position of the rotor is increased and vibration and noise are increased.

Further, in the stepping motor having the structure shown in FIG. 10, when the tooth length of the pole teeth 5, 6 and 11, 12 is to be increased to increase the torque, or six or more pole teeth are formed. In this case, there is a problem that it becomes difficult to press the pole teeth 5, 6 and 11, 12 with a small diameter stepping motor having an outer diameter of 12 [mm] or less.

Further, in order to obtain a sufficient magnetic flux in a small diameter stepping motor having an outer diameter of 12 mm or less, it is attempted to increase the plate thickness of the pole teeth 5, 6 and 11, 12 (for example, the outer diameter 10
(When the thickness of the pole teeth is 0.6 [mm] or more with a stepping motor of [mm]), the life of the mold for processing the pole teeth 5, 6 and 11 and 12 can be shortened and mass production can be performed. There is a problem that becomes difficult.

The present invention has been made in consideration of the above points, and has a structure capable of improving the assembling accuracy (particularly, the phase difference accuracy of the A phase and the B phase) and corresponding to miniaturization (diameter reduction). It is intended to propose a stepping motor.

[0010]

In order to solve the above problems, according to the present invention, the first phase coil portion 8 and the second phase coil portion 13 are provided at positions facing the peripheral side surface of the rotor magnet 22. For the first phase, which are arranged side by side in the direction of the rotation axis 21 of the net 22, form the magnetic path of the magnetic flux generated by the first phase coil portion 8 and receive the magnetic flux from the rotor magnet 22. Pole teeth 25A is the first
The second phase coil is disposed between the phase coil section 8 and the rotor magnet 22 to form a magnetic path of the magnetic flux generated by the second phase coil section 13 and to receive the magnetic flux from the rotor magnet 22. In the stepping motor 20 in which the phase pole tooth 25B is arranged between the second phase coil portion 13 and the rotor magnet 22, the first phase pole tooth 2
5A and the pole teeth 25B for the second phase are punched from a predetermined flat plate member 23 into a predetermined shape, and then bent into a cylindrical shape to be integrally formed.

[0011]

[Function] The first phase polar tooth 25A and the second phase polar tooth 25
By integrally forming B by press punching, the phase difference accuracy of the first phase and the second phase can be increased to the accuracy of the press punching.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1 in which parts corresponding to those in FIG. 10 are designated by the same reference numerals, 20 denotes a stepping motor as a whole, and a rotor magnet 2 integrated with a rotary shaft 21.
A cylindrical inner pole tooth member 25 is provided so as to face the outer peripheral surface of 2.

The inner pole tooth member 25 is, as shown in FIG.
A-phase (first phase) protruding on both sides in a trapezoidal shape by punching a flat plate member 23 made of an iron-based material
Pole teeth 25A for B and the pole teeth 25B for B phase (second phase) are formed, and the flat plate member 23 is bent (curling) into a cylindrical shape as shown in FIG. Are joined by a joining process such as welding to form the pole teeth 25A for the A phase and the pole teeth 25B for the B phase on both sides of the cylindrical open ends 26A and 26B.

The pole teeth 25A and 25B are out of phase by a predetermined angle α (90 °) as shown in FIG. 2 as an electrical angle in which one set of S pole and N pole of the rotor magnet 22 is 360 °. It is formed in the open position.

Further, a ring-shaped yoke member 31 shown in FIG. 4 is fitted to the outer peripheral surface of the inner pole tooth member 25, and as shown in FIG. 5, both opening ends 26A and 26B ( The concave portion 31A formed in the inner peripheral portion of the yoke member 31 is engaged with the positioning projection 28 that is formed in the central portion of FIG. 3).

On the outer peripheral surface of the inner pole tooth member 25, the coil bobbin 9 for A phase is fitted on the pole tooth 25A side for A phase, and the B side pole tooth 25B for B phase is fitted. The coil bobbin 15 is fitted (FIG. 1).

The coil bobbins 9 and 15 have windings 8 and 1
3 is wound, and a part thereof is connected to terminals (not shown) provided on the coil bobbins 9 and 15, respectively, so that an electric current can be supplied from the outside.

Here, on the outer peripheral portion of the yoke member 31, an external tooth yoke member 33 for A phase and an external tooth yoke member 43 for B phase are provided.
Are fitted together (FIG. 1). As shown in FIG. 6, the outer tooth yoke member 33 has a cylindrical container shape as a whole by drawing, and cuts and raises a part of the bottom surface portion 33C in a direction parallel to the peripheral side surface portion 33B to form the pole teeth 33D.
Is formed.

A recess 33A (FIG. 1) is formed on the outer peripheral portion of the outer tooth yoke member 33, and when the outer tooth yoke member 33 is fitted on the outer peripheral portion of the yoke member 31, the yoke member 3 is formed.
The concave portion 33A is engaged with the positioning projection 31B formed on the outer peripheral portion of No. 1 so that the outer tooth yoke member 33 is attached to the yoke member 31 (that is, to the A-phase pole tooth 25A of the inner pole tooth member 25). The mounting position) is positioned.

The external tooth yoke member 43 for the B phase has the same structure, but the recessed portion 43A (FIG. 1) of the external tooth yoke member 43 is formed at the outer tooth yoke portion 33 for the A phase. It is formed at a position shifted in phase by 90 ° in electrical angle from the formation position of the concave portion 33A.

Therefore, when the B-phase external tooth yoke member 43 is fitted into the outer peripheral portion of the yoke member 31 so that the recess 43A and the positioning projection 31B are engaged with each other, the external tooth yoke member 43 The mounting position with respect to the yoke member 31 (that is, the mounting position with respect to the B-phase pole tooth 25B of the inner pole tooth member 25) is positioned.

Accordingly, in a state where the outer tooth yoke members 33 and 43 are fitted to the yoke member 31 from the A-phase side and the B-phase side, respectively, the pole teeth 33D of the outer tooth yoke member 33 are the same as those of the inner pole tooth member 25. The pole teeth 43D of the outer tooth yoke member 43 are inserted between the plurality of A-phase pole teeth 25A with a predetermined gap, and the pole teeth 43D of the outer-tooth yoke member 43 are the plurality of B-phase pole teeth 25B of the inner pole tooth member 25.
(Electrical angle is 90 ° out of phase with the A-phase pole tooth 25A) A predetermined gap is interposed between them. Thus, the outer tooth yoke members 33 and 34 are fixed to the yoke member 31 by spot welding or caulking or gluing.

The through hole 33E formed in the bottom surface portion 33C of the outer tooth yoke member 33 has a bearing 3 made of a sintered oil-impregnated alloy.
5 is fitted and fixed by a method such as caulking or press fitting, and the rotary shaft 21 is rotatably supported by this bearing 35.

A resin magnet as the rotor magnet 22 is fixed to the rotary shaft 21 by a method such as adhesion, integral molding (insert molding), press fitting, or the like, whereby the rotor magnet 22 has a cylindrical inner pole. It is rotatably held inside the tooth member 25.

In the above structure, the pole teeth 25A and 25B of the inner pole tooth member 25 are integrally formed by press punching the flat plate member 23.
The accuracy of the phase difference (electrical angle 90 °) between the pole teeth 25A and 25B is realized by the accuracy of the press punching.

Therefore, compared with the conventional case in which the pole teeth are separately formed for the A phase and the B phase, the phases are mechanically aligned at the time of assembly, Since the phase difference accuracy of the B phase can be significantly improved, the A phase pole tooth 25A and the B phase pole tooth 25B
It is possible to reduce the detent torque due to the formation error of. Therefore, vibration and noise generated by the daytent torque can be reduced.

Further, by forming the inner pole tooth member 25 by press punching and curling, it is not necessary to bend the pole teeth as in the conventional case, and thus it is possible to perform finer processing. Therefore, even in a small-diameter stepping motor (outer diameter 12 [mm] or less), the pole teeth 25A and 25B can be lengthened and a large number of pole teeth of 6 or more can be formed. Even in the ping motor, higher torque can be realized.

Further, by eliminating the need for bending the pole teeth, it is possible to avoid shortening the life of the die even if the thickness of the pole teeth is further increased. Therefore, it is possible to mass-produce a stepping motor that can thicken the pole teeth and obtain a sufficient magnetic flux, and to increase the inner pole teeth 25A.
And 25B and the outer pole teeth 33D and 43D can be improved in pitch accuracy.

According to the above construction, a stepping motor having a small diameter (small size) can be realized with higher accuracy and higher torque.

In the above embodiment, the case where only the inner pole tooth member 25 is formed from the flat plate member 23 by press punching and curling has been described, but the present invention is not limited to this, and the outer tooth 33D ( 43D) may also be formed by the same processing method.

That is, as shown in FIG. 7 in which parts corresponding to those in FIG. 1 are designated by the same reference numerals, the stepping motor 50 has an A-phase outer pole tooth 51 and a B-phase outer pole tooth 55 as a flat plate member. It is formed by press punching and curling, and is held by the side members 52 and 53. The side members 52 and 53 are held by a cylindrical outer yoke 54. By forming the outer pole teeth 51 and 55 by such a processing method, it is possible to further improve the accuracy in the same manner as in the above case.

In the above embodiment, the case where the inner pole tooth member 25 and the yoke member 31 are formed separately has been described, but the present invention is not limited to this and may be formed integrally. That is, as shown in FIG. 8 in which parts corresponding to those in FIG.
Is a yoke member 31 (FIG. 1) and pole teeth 25A (25B)
(FIG. 1) has an A-phase inner pole tooth member 72 and a B-phase inner pole tooth member 73 integrally formed.

As shown in FIG. 9, the inner pole tooth members 72 and 73 are formed by press punching a flat plate member 80 so as to form pole teeth on one side as shown in FIG. 9A, and then curling it. Inner pole tooth members 72 and 73 are obtained by forming into a flange shape as shown in FIG. 9B by working and pressing. By joining the flange portions of the inner pole tooth members 72 and 73 to each other, the inner pole teeth for the A phase and the B phase as shown in FIG. 8 can be formed.

Similarly, the outer pole teeth are formed in a flange shape from the flat plate member 80 to obtain outer pole teeth 76 and 77 (FIG. 9B), and the pole tooth portions of the outer pole teeth 76 and 77 are obtained. 8 are inserted into the pole tooth portions of the inner pole teeth 72 and 73 with a predetermined gap therebetween to obtain outer pole teeth 76 and 77 facing the inner pole teeth 72 and 73, respectively, as shown in FIG. In this way, the inner pole tooth members 72 and 73
Of the stepping motor 70 having a simpler structure by integrally forming each of them with the yoke member 31 (FIG. 1).
Can be obtained.

Further, in the above-mentioned embodiment, the case where the pole teeth 33A (and 43A) are cut and raised from the member drawn into the cylindrical container shape has been described as the method of processing the outer tooth yoke member 33 (and 43). However, the present invention is not limited to this, and the pole teeth 33A (and 43A) may be cut and raised first, and then drawn into a cylindrical shape.

In the above embodiment, the case where the sintered oil-impregnated alloy is used as the bearing 35 has been described, but the present invention is not limited to this, and a bearing made of resin having good sliding characteristics,
Various other bearings may be used.

Further, in the above embodiment, the case where the resin magnet is used as the rotor magnet 22 has been described, but the present invention is not limited to this, and various other magnets can be used.

[0039]

As described above, according to the present invention, the inner pole teeth for the A phase and the inner pole teeth for the B phase are formed from the flat plate member by press punching and bending into a cylindrical shape, respectively. As a result, the accuracy of the relative phase of the A-phase inner pole teeth and the B-phase inner pole teeth can be further improved, and a high-torque compact stepping motor with good mass productivity can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a stepping motor according to the present invention.

FIG. 2 is a plan view showing a pole tooth shape formed by press punching a flat plate member.

FIG. 3 is a schematic perspective view showing a cylindrical inner pole tooth member obtained by curling a flat plate member having pole teeth formed by press punching.

FIG. 4 is a side view showing the shape of a yoke member.

FIG. 5 is a partial perspective view showing an engaged state of an inner pole tooth member, a yoke member, and an outer tooth yoke member.

FIG. 6 is a partial perspective view showing the configuration of an external tooth yoke member.

FIG. 7 is a sectional view showing a stepping motor in which an external tooth member is formed from a flat plate member by press punching and curling.

FIG. 8 is a cross-sectional view showing a stepping motor in which an inner pole tooth member and a yoke member are integrally formed.

FIG. 9 is a side view showing the configuration in the case where the inner pole tooth member and the yoke member are integrally formed.

FIG. 10 is a perspective view showing a configuration of a conventional stepping motor.

FIG. 11 is a cross-sectional view showing a state of alignment of the A-phase pole teeth and the B-phase pole teeth in the conventional stepping motor.

[Explanation of symbols]

20, 50, 70 ... Stepping motor, 25, 7
2, 73 ... Inner pole tooth member, 31 ... Yoke member, 33,
43, 51, 76, 77 ... Outer pole tooth member.

Claims (1)

[Claims] 1. A first-phase coil portion and a second-phase coil portion are arranged side by side in a direction of a rotation axis of the rotor magnet at positions facing a peripheral side surface of the rotor magnet. Magnetic poles for the first phase, which form a magnetic path of the magnetic flux generated by the rotor portion and receive the magnetic flux from the rotor magnet, are arranged between the coil portion of the first phase and the rotor magnet. The second-phase coil portion is configured to form the magnetic path of the magnetic flux generated by the second-phase coil portion and receive the magnetic flux from the rotor magnet. In the stepping motor arranged between the rotor magnets, the pole teeth for the first phase and the pole teeth for the second phase are press punched from a predetermined flat plate member into a predetermined shape, and then formed into a cylindrical shape. For bending A stepping motor characterized by being formed more integrally.