JPH1075559A - Stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to reduce the defect in soldering between annular stators. SOLUTION: A stepping motor includes a magnet rotor 4 with a rotating axle 41, first and second bearing plates 5 and 6 for supporting the magnet rotor 4, and first and second annular stators 1 and 2, each having a hollow concentric laminated body, between the first and second bearing plates 5 and 6. The first and the second annular stators 1 and 2 include first and second outer yokes 11 and 21 with an almost annular shape, first and second inner yokes 12 and 22 with an almost annular shape on the opened side of these outer yokes 11 and 21, and first and second excitation coils 13 and 23. The first and second excitation coils 13 and 23 are stored between the outer yokes 11 and 21 and the inner yokes 12 and 22. While the inner yokes 12 and 22 are adjoined to each other, given end parts 17 and 27 of the outer yokes 11 and 21 on the opened side are welded with each other to form a coaxial concentric laminated body. The first and the second outer yokes 11 and 12 have thick parts 17b and 27b at each welding part thereof. The thick parts 17b and 27b are thicker than the other surrounding parts 17a and 27a.

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 joint structure of two stators constituting each phase in a two-phase PM type stepping motor.

[0002]

2. Description of the Related Art Conventionally, a PM type stepping motor has been
It is widely used as an actuator component in the fields of various OA equipment, home appliances, automobiles, etc. In many cases, two annular stators consisting of an exciting coil and an annular yoke wound concentrically are concentrically laminated to form an inner part. Is provided with a hollow laminated body, and a magnet rotor having a rotating shaft is rotatably supported in the hollow of the laminated body. In recent years, it has attracted attention as a movement of analog instruments.

In this type of stepping motor, as shown in Japanese Patent Application Laid-Open No. Hei 5-161332, each of two annular stators is arranged on an annular yoke-shaped outer yoke and an opening side thereof. There is a type in which an exciting coil is housed in a space formed by an outer yoke and an inner yoke in the form of a circular plate, and many stepping motors of this type are configured as follows. A predetermined portion of the open end of each outer yoke facing each other is welded and joined to each other using an electric welding means such as laser or plasma welding to fix the annular stators together.

[0004]

However, such electric welding is performed by partially melting a predetermined portion on the opening side end of each outer yoke by electric energy such as laser or plasma, and joining. Predetermined portions to be welded and joined may be burned out due to high heat, resulting in poor welding. In particular, as disclosed in Japanese Utility Model Laid-Open No. 5-33673, when a notch-shaped stepped portion to be fitted to the outer peripheral edge of the inner yoke is formed at the inner edge of the open end of the outer yoke, Since the opening-side end of the yoke is thin, the heat allowance is inevitably reduced, and poor welding is likely to occur.

The present invention has been made in view of these points, and has as its main object to provide a stepping motor capable of reducing welding defects between annular stators.

[0006]

In order to achieve the above object, the present invention provides a first and second outer yokes each having a substantially annular cup shape and a first annular yoke-shaped first yoke arranged on the opening side thereof. The first and second exciting coils are housed between the first and second inner yokes, respectively, and the opening ends of the outer yokes are welded to each other in a state where the inner yokes are adjacent to each other. First and second annular stators forming a hollow concentric laminate,
A magnet rotor rotatably disposed through a rotating shaft in the hollow of the concentric laminated body of each of the annular stators, and increasing the thickness of at least the welding corresponding portion of each of the outer yokes with respect to the periphery thereof. It is formed.

Each of the outer yokes has a notch-shaped step at the inner edge of the opening end thereof to be fitted to the outer edge of the inner yoke. By forming the portion, the portion corresponding to the welding is made thicker around its circumference.

The first and second outer yokes each having a substantially annular cup shape and the first and second outer yokes each having a substantially annular plate shape disposed on the opening side thereof.
The first and second exciting coils are respectively housed between the inner yoke and the inner yoke, and the inner yoke is adjacent to each other, and the opening ends of the outer yokes are welded to each other to form a hollow inside. A first and a second annular stators forming a concentric laminated body, and a magnet rotor rotatably disposed through a rotating shaft in the hollow of the concentric laminated body of each of the annular stators; The thickness of at least the opening side region including the welding corresponding portion of the yoke is formed to be thicker than the periphery thereof.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the reference numerals of the embodiments. A stepping motor according to the present invention comprises a magnet rotor 4 having a rotating shaft 41 and a magnet shaft 4 supporting the magnet rotor 4. First and second bearing plates 5 and 6 and first and second bearing plates 5 and 6 which are arranged between the first and second bearing plates 5 and 6 to form a concentric laminate having a hollow interior.
The first and second annular stators 1 and 2 are provided with first and second outer yokes 11 and 21 each having a substantially annular cup shape and provided on the opening sides thereof. The first and second inner yokes 12, 22 having a substantially annular plate shape, the first and second outer yokes 11, 21, and the first and second inner yokes 12,
22, the first and second excitation coils 13,
23, each of which has the inner yokes 12, 22 adjacent to each other and welds predetermined portions of the outer yokes 11, 21 to the opening sides 17, 27 to form the concentric laminate. In the portions corresponding to the welding of the first and second outer yokes 11 and 21, the thickness of this portion is set at the periphery (the thin portion 1).
7a, 27a) the thick portion 17 formed thicker than the thickness
By providing b and 27b, the heat allowance in the welded portion is increased, and welding defects such as burnout are reduced.

According to the present invention, the outer yokes 11, 21 have notch-shaped steps 18, 28 at the inner edges of the opening sides 17, 27, respectively, to be fitted with the outer edges of the inner yokes 12, 22, respectively. By forming the step portions 18 and 28 at least excluding the portions corresponding to welding, the portions other than the portions corresponding to welding are thinned portions 17.
a, 27a, and the portions corresponding to the welding are thinned portions 17a, 27
By forming the thick portions 17 and 27a thicker than a, the heat allowance increases in the welded portion due to the thick portions 17 and 27a, and welding defects such as burnout can be reduced. Steps 18 and 2 except for the welding-supported locations
8, the adhesion between the outer and inner yokes 11, 12, 21, 22 is increased, and the outer and inner yokes 11, 12, 21,
The backlash between the 22 is suppressed and the magnetic circuit efficiency is increased.

Further, the stepping motor according to the present invention comprises:
A magnet rotor 4 having a rotating shaft 41, and first and second bearing plates 5 supporting the magnet rotor 4;
6 and first and second annular stators 1 and 2 which are arranged between the first and second bearing plates 5 and 6 and form a concentric laminated body having a hollow inside. The two annular stators 1 and 2 include a substantially annular cup-shaped first and second outer yokes 11 and 21 and a substantially annular plate-shaped first and second inner yokes disposed on the opening side thereof. 12 and 22, and first and second exciting coils 13 and 23 housed between the first and second outer yokes 11 and 21 and the first and second inner yokes 12 and 22, respectively. The concentric laminate is formed by welding predetermined portions of the open ends 17, 27 of the outer yokes 11, 21 in a state where the inner yokes 12, 22 are adjacent to each other. Each outer yoke 1 including parts
The thicker portions 17b and 27b are formed in the opening-side regions R of the portions 1 and 21 so that the thickness of this portion is larger than the thickness of the surrounding portions. Poor welding such as breakage is reduced.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an exploded perspective view of a stepping motor according to a first embodiment of the present invention, FIG. 2 is an external perspective view showing an assembled state thereof, and FIG. 3 is a cross section taken along line XX of FIG. FIG. 4A is a cross-sectional view of a main part showing a state before a welding process at a welded portion (a partially enlarged view of FIG. 3) of each annular yoke.
FIG. 4B is a cross-sectional view of a main part showing a joining portion other than a welding portion of each annular yoke.

As shown in FIGS. 1 to 3, the stepping motor according to the present embodiment includes a first annular stator 1 located on the upper side, a second annular stator 2 located on the lower side, and An annular spacer member 3 disposed between the annular stators 1 and 2;
A magnet rotor 4 disposed in the annular stator, and first and second magnet rotors 4 for supporting both ends of the magnet rotor 4.
Disk-shaped first and second opposed annular stators 1 and 2
And second bearing plates 5 and 6.

The first and second annular stators 1 and 2 include first and second outer yokes 11 and 21 each having a substantially annular cup shape made of a magnetic metal material. , 21
The first and second inner yokes 12 and 22 made of a substantially annular plate-shaped magnetic metal material having an outer diameter substantially equal to the opening diameter of the first and second exciting coils 13 and 23 are wound. 1st, 2nd
And the first and second annular bobbins 14, 24 are provided with first and second outer yokes 11, 21, respectively.
And the first and second inner yokes 12 and 22 arranged in a housed state so as to close these opening sides.

First and second outer and inner yokes 11, 12, 2
Numerals 1 and 22 extend in the axial direction of the magnet rotor 4 at the center thereof, and are arranged in an annular comb-teeth shape in the first and second annular bobbins 14 and 24, each slightly larger than the outer diameter of the magnet rotor 4. Pole teeth 15, 1 combined with
6, 25, 26, and these pole teeth 15, 16, 25,
26 are arranged along the inner circumference of the first and second annular bobbins 14 and 24 in the assembled state.

The outer edges of the first and second inner yokes 12 and 22 are provided on the inner edges of the open ends 17 and 27 of the first and second outer yokes 11 and 21 respectively. Notched step portions 18 and 28 are formed to be received and fitted in the annular stator in the mounting direction (see FIG. 4B for the step portion 18). The first and second outer yokes 1 and 2 are formed at positions other than the portions corresponding to welding described later, and are formed slightly deeper than the plate thickness of the first and second inner yokes 12 and 22. Can accommodate a part of both sides of the spacer member 3.

By forming the step portions 18 and 28, the first and second outer yokes 1 and 2 on which these portions are formed are formed.
The opening-side end portions 17 and 27 are thin and thin portions 17a and 17a.
27a, on the other hand, the opening-side ends 17, 2 of the first and second outer yokes 1, 2 in which the steps 18, 28 are not formed.
The seven portions (= weld corresponding portions) are thick portions 17b and 27b thicker than the thin portions 17a and 27a (see FIG. 4B for the thin portions 17a and 17b).

The first and second inner yokes 12, 22 corresponding to the thick portions 17b, 27b have thick portions 17
Notches 19 and 29 are formed respectively to escape the b and 27b. In this case, the stepped portions 18 and 28 and the inner yoke 12,
The first and second outer and inner yokes 11, 12, 21, 22 are positioned in the axial direction through the fitting of the outer peripheral edge of the outer peripheral portion 22 with the outer peripheral edge.
27b, the first and second outer and inner yokes 11,
Positioning in the circumferential direction of 12, 21, 22 is performed.

The spacer member 3 is made of a non-magnetic and conductive metal material such as non-magnetic stainless steel and aluminum, and suppresses mutual magnetic interference between the first and second annular stators 1 and 2. The notches 19, 29 of the first and second inner yokes 12, 22 (thick portions 17b, 27 serving as welding corresponding portions of the first and second outer yokes 11, 21).
A projecting portion 31 projecting outward is formed at an outer peripheral edge position corresponding to b), and the projecting portion 31 is formed to be slightly thinner than the main body side of the spacer member 3.

Here, a method of fixing the first and second annular stators 1 and 2 including the spacer member 3 will be described. The first and second annular stators 1 and 2 are formed by first and second inner yokes. 12 and 22 are concentrically stacked with the spacer member 3 interposed therebetween and the opening ends 17 and 27 of the first and second outer yokes 11 and 21 facing each other. As shown in a), the thick portions 17b and 27b serving as welding corresponding portions of the opening ends 17 and 27 of the first and second outer yokes 11 and 21 are sandwiched between the projecting portions 31 of the spacer member 3. Abut the spacer member 3 in this state.
By supplying electric energy such as laser, plasma, and large current from outside to the thick portions 17b and 27b including the projecting portion 31, the projecting portion 31, the thick portions 17b and 27b,
A part of the second inner yokes 12, 22 is melted and welded to form a welded portion S as shown in FIGS.
Of the annular stators 1 and 2 is achieved.

At this time, as shown in FIG. 4B, the first and second outer yokes 11 and 21 other than the portions corresponding to the welding are formed as shown in FIG.
The ends of the thin portions 17a and 27a face each other with a predetermined space therebetween.

Thus, the first and second annular stators 1 and 2 including the spacer member 3 form a concentric laminate having a hollow portion communicating with the axial direction at the center, and the hollow portion of the concentric laminate is formed. Accommodates the magnet rotor 4.

The magnet rotor 4 has a plurality of magnetic poles extending in the axial direction with a predetermined width (pitch) on its peripheral surface and alternately arranged N and S along the rotational direction. When stored in a concentric laminate, the pole teeth 15, 16,
25 and # 26 at a predetermined interval. The magnet rotor 4 has a rotating shaft 41 at its center in the circumferential direction.
And both ends of the rotating shaft 41 are rotatably supported through a pair of first and second bearing plates 5 and 6.

The first and second bearing plates 5 and 6 correspond to the first and second bearing plates.
Bearing members 51 and 61 for supporting the rotating shaft 41 of the magnet rotor 4 are fixed to the center of the second outer yokes 11 and 21 on the bottom side in the circumferential direction.

The stepping motor thus configured supplies the pulse signal to both or any one of the first and second exciting coils 13 and 23, so that the first outer and inner yokes 11 are provided. , 12 and the second outer and inner yokes 21 and 22 are magnetized to rotate the magnet rotor 4.

As described in detail above, in the present embodiment, the magnet rotor 4 having the rotating shaft 41, the first and second bearing plates 5, 6 for supporting the magnet rotor 4 are provided.
The first and second annular stators 1 and 2 are arranged between the first and second bearing plates 5 and 6 and form a concentric laminated body having a hollow inside. The first and second outer yokes 1 each have a substantially annular cup shape.
, 21, first and second inner yokes 12, 22 each having a substantially annular plate shape arranged on the opening side, first and second outer yokes 11, 21, and first and second inner yokes 12, 22. It has first and second excitation coils 13 and 23 housed between the inner yokes 12 and 22, respectively, and the opening sides of the outer yokes 11 and 21 with the inner yokes 12 and 22 adjacent to each other. The concentric laminated body is formed by welding predetermined portions of the end portions 17 and 27 to each other. (Thin parts 17a, 27
By forming the thick portions 17b and 27b which are formed thicker than the thickness of a), it is possible to increase the heat allowance at the welding corresponding portion and reduce welding defects such as burnout due to high heat during welding. Can be.

In this embodiment, the outer yokes 11, 21
Are attached to the inner edges of the inner yokes 12, 2
2 has cutout-shaped steps 18 and 28 fitted to the outer peripheral edge of the second section 2. By forming the steps 18 and 28 at least except for the portions corresponding to welding, the thin portions 1 other than the portions corresponding to welding are formed.
7a and 27a, and the portions corresponding to the welding are thin portions 17a and 2
By forming the thick portions 17 and 27a thicker than the thick portion 7a, the thick portions 17 and 27a increase the heat allowance at the welding location, thereby reducing welding defects such as burnout and the like. Steps 18 and 2 except for the welding-supported locations
8, the adhesion between the outer and inner yokes 11, 12, 21, 22 is increased, and the outer and inner yokes 11, 12, 21,
It is possible to suppress the backlash between the 22 and to improve the magnetic circuit efficiency.

In the embodiment, since the spacer members 3 are interposed between the annular stators 1 and 2, mutual magnetic interference between the annular yokes 1 and 2 can be suppressed. Is not required, the thick portions of the outer yokes 11 and 21 may be directly welded to each other.

In this embodiment, the outer and inner yokes 11, 12, 21, 22 are positioned in the axial direction through fitting of the steps 18, 28 with the outer peripheral edges of the inner yokes 12, 22. Notch portions 19 and 29 and thick portion 17b,
27b, the outer and inner yokes 11, 12, 2
The outer and inner yokes 11, 12, 21, and 22 can be directly and reliably positioned without providing a dedicated positioning portion separately by positioning the first and second circumferential portions in the circumferential direction. Can be.

The thick portions 17b and 2 serving as welding corresponding portions
7b can be set arbitrarily except that it is desirable that the width in the circumferential direction is slightly larger than the width of the welded portion S (see FIG. 2) formed by welding. For example, in FIG. The thick portions 17b and 27b may be continuously formed in the circumferential direction of the yokes 11 and 21 so that a plurality of portions in the region may be welded. On the other hand, it is only necessary that it be formed thicker.

As shown in FIG. 5, the thick portions 17b and 27b are provided on the outer yokes 11 and 12 as a second embodiment of the present invention.
The thicker portions 17b, 27b thicker than the surroundings may be formed by projecting the opening-side end region R of the outside toward the outside. In this case, the opening-side end portions of the outer yokes 11, 21 may be formed. The entire region in the circumferential direction of the region R may be formed as the thick portions 17b and 27b, and any portion in the circumferential direction may be a portion corresponding to welding, or the circumferential direction of the opening-side end regions R of the outer yokes 11 and 21 may be used. Are partially thickened in portions 17b and 27b.
In this regard, a single predetermined portion or a plurality of portions in the region where the thick portions 17b and 27b are partially formed may be used as the welding corresponding portions, and the openings including at least the welding corresponding portions of the outer yokes 11 and 21 may be used. It is sufficient that the thickness of the side region R is thicker than its surroundings.

[0033] With this configuration as well, it is possible to increase the heat allowance at the welding-corresponding portion, and it is possible to reduce welding defects such as burnout due to high heat during welding.

[0034]

As described in detail above, the present invention is characterized in that the first and second outer yokes having a substantially annular cup shape and the first and second outer yokes having a substantially annular plate shape disposed on the opening sides thereof are provided. The first and second exciting coils are respectively housed between the inner yoke and the inner yoke, and the inner yoke is adjacent to each other, and the opening ends of the outer yokes are welded to each other to form a hollow inside. A first and a second annular stators forming a concentric laminated body, and a magnet rotor rotatably disposed through a rotating shaft in the hollow of the concentric laminated body of each of the annular stators; By forming the thickness of at least the portion corresponding to the weld of the yoke to be thicker than the periphery thereof, it is possible to provide a stepping motor capable of increasing the heat allowance in the welded portion and reducing welding defects such as burnout.

Further, according to the present invention, each of the outer yokes has a notch-shaped step at the inner edge of the opening-side end thereof so as to fit with the outer edge of the inner yoke. By forming the corresponding portion except for the corresponding portion, the thickness of the corresponding portion is increased with respect to the circumference thereof, thereby improving the adhesion between the outer and inner yokes while reducing welding defects such as burnout. be able to.

Further, the present invention relates to a substantially annular cup-shaped first,
The first and second exciting coils are respectively accommodated between the second outer yoke and the first and second inner yokes each having a substantially annular plate shape arranged on the opening side, and the inner yokes are adjacent to each other. In this state, predetermined portions of the outer yokes on the opening side are welded to each other to form a concentric laminated body having a hollow interior.
And a magnet rotor rotatably disposed through a rotating shaft in the hollow of the concentric laminated body of each of the annular stators, and an opening-side region including at least the welding corresponding portion of each of the outer yokes. The thickness of the outer and inner yokes can be increased while reducing welding defects such as burn-out due to the formation of a thicker wall with respect to the periphery.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a stepping motor according to a first embodiment of the present invention.

FIG. 2 is an external perspective view showing an assembled state of FIG. 1;

FIG. 3 is a sectional view taken along line XX of FIG. 2;

FIG. 4A is a cross-sectional view of a main part showing a welded portion of each annular yoke before a welding process, and FIG. 4C is a cross-sectional view of a main part showing a joined portion other than the welded portion of each annular yoke. FIG.

FIG. 5 is a sectional view of a main part of a stepping motor according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st annular stator 2 2nd annular stator 3 spacer member 4 magnet rotor 5 1st bearing plate 6 2nd bearing plate 11,21 1st, 2nd outer yoke 12,22 1st, 2nd Inner yokes 13,23 First and second excitation coils 14,24 First and second annular bobbins 15,16,25,26 Polar teeth 17,27 Open end 17a, 27a Thin part 17b, 27b Thick Portion 18, 28 Step portion 19, 29 Notch 31 Projection S Weld R Opening side area

Claims (3)

[Claims] The first and second outer yokes each having a substantially annular cup shape and the first and second inner yokes each having a substantially annular plate shape disposed on the opening side thereof. A first and a second concentric laminated body having a hollow interior by welding predetermined portions of the open ends of the outer yokes while accommodating the two exciting coils and adjoining the inner yokes. 2 and a magnet rotor rotatably disposed through a rotating shaft in the hollow of the concentric laminated body of each of the annular stators, and having a thickness of at least the welding corresponding portion of each of the outer yokes. A stepping motor characterized by being formed thicker around the periphery. 2. Each of the outer yokes has a notch-shaped step at the inner edge of the open end thereof to be fitted to the outer edge of each of the inner yokes. 2. The portion corresponding to the weld is made thicker around its circumference in the circumferential direction by forming it.
The stepping motor as described. 3. The first and second outer yokes each having a substantially annular cup shape and the first and second inner yokes each having a substantially annular plate shape disposed on the opening side thereof. A first and a second concentric laminated body having a hollow interior by welding predetermined portions of the open ends of the outer yokes while accommodating the two exciting coils and adjoining the inner yokes. And a magnet rotor rotatably disposed through a rotating shaft in the hollow of the concentric laminated body of each of the annular stators, and an opening side of each of the outer yokes including at least the welding corresponding portion. A stepping motor characterized in that the thickness of a region is formed thicker than its surroundings.