JPH0923619A - Commutator for miniature motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress cracking of a varistor by positioning a commutator holder in the radial direction using the core ties of armature and press fitting a varistor to a shaft and a riser while positioning by means of the commutator holder thereby ensuring the contact between the riser and a conductive layer and the conduction of a winding being applied to the riser. SOLUTION: A commutator holder 1 is positioned in the rotational direction in relation to the core teeth 7 of armature and a varistor 3 is press fitted to a shaft 6 and a riser 2 while being positioned in relation to the commutator holder 1 or the riser 2. Consequently, contact between the riser 2 and an electrode, i.e., a conductive layer 4, provided on the outer circumferential surface of varistor 3 is ensured and thereby the conduction with winding is ensured. More specifically, the commutator holder 1, the riser 2 and the varistor 3 are constructed from one direction. This structure suppresses cracking of varistor 3 due to press fit as compared with a planar varistor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a commutator device for a small motor equipped with a varistor, and more particularly to a commutator for preventing electromagnetic noise generated from a motor, which can be assembled without using solder or the like. The present invention relates to a commutator device for a motor.

[0002]

2. Description of the Related Art Conventionally, a varistor element has been used to prevent noise in a small motor. For example, the varistor element attached to prevent radio noise from the mirror motor is
A technique using an excessively large number of man-hours and an expensive silver-containing solder is conventionally known for the assembling. Also, there is a technique to attach a ring varistor to the coil attachment part of the commutator by soldering,
Technology using a cylindrical varistor as a commutator
-103055), etc. are known.

Further, a work part for holding the commutator of the ring varistor, a work process for determining the relative position of the varistor, and a work process for soldering to the hold part for fixing the varistor and energizing it have been required.

Generally, a varistor is a ceramic component, and it has a drawback that it is difficult to assemble because it suffers from defects such as cracking and chipping due to impact load. Therefore, the technology of using a cylindrical varistor as a commutator (actually developed 55-76683).
JP-A-61-185264, etc.) have been proposed.

However, in these proposed techniques, it is difficult to directly press fit the armature shaft to the armature shaft because the varistor is made of ceramic. As a result, the cylindrical surface of the cylindrical varistor has a large eccentricity with respect to the rotation of the shaft, resulting in poor contact between the commutator and the brush, resulting in an increase in electromagnetic noise.

For press-fitting, an idea has been proposed such that an electrode is formed on the inner circumference of the hole of the plate varistor and press-fitted, or an article in which the varistor itself has elasticity is press-fitted, but cracking or assembly occurs. There are many problems in terms of sex. When press-fitting a varistor, the method of press-fitting the hole of the varistor into resin, metal, etc. is mainly used, but at this time, tensile stress is generated in the varistor. Generally, ceramics have a tensile stress resistance <<<< compressive stress resistance, so that they are assembled through a material having elasticity to relieve the tensile stress, resulting in a complicated structure.

There is also known a technique in which a resin or the like is mixed in a varistor component for press-fitting into a motor shaft, and after press-molding the varistor, a press-fitting dimension is obtained by cutting.
There is a problem that the effect of absorbing noise is inferior as compared with the case where only the varistor component is included due to the mixture of resin and the like.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to mount a varistor on a commutator by means of press-fitting, ultrasonic staking, heat staking, clipping, etc., without using solder, to secure electrical contact and fixing. In addition to providing a commutator device to which a varistor suitable for automatic assembly can be attached.

Another object of the present invention is to provide a commutator device capable of adapting to variations in the presence or absence of varistor with a minimum change configuration.

[0010]

A commutator device for a small motor according to claim 1 of the present invention comprises a shaft of an armature, and a commutator holder assembled by press fitting between the shaft and the shaft.
The commutator comprises: a riser engaged with the shaft through a commutator holder; a cylindrical varistor press-fitted into the shaft; and a conductive layer formed on an outer peripheral surface of the varistor. The child holder, the riser, and the varistor are assembled from one direction, and positioning of the commutator holder in the rotational direction is performed by the relationship with the core teeth of the armature, and the varistor is related with the commutator holder or the riser. Is positioned and pressed into the shaft and the riser to secure contact between the riser and the conductive layer, and to secure continuity with the winding wound around the riser.

A commutator device for a small motor according to claim 2 of the present application is a commutator holder assembly in which a shaft, a core tooth and a commutator holder are assembled, and a riser fixed to the commutator holder assembly. And a cylindrical varistor that is engaged with the commutator holder assembly and positioned in the rotational direction, and the commutator holder assembly, the riser, and the varistor are assembled from one direction. Then, the cylindrical varistor is positioned in the rotational direction between the cylindrical varistor and the assembly of the commutator holder, and is inserted into the shaft.
While pressing the cylindrical varistor in the direction of the riser to ensure electrical contact between the cylindrical varistor electrode and the riser,
The feature is that the varistor is fixed. At this time, it is preferable that the riser is bent so as to have a spring property.

A commutator device for a small motor according to claim 4 of the present application is a commutator holder assembly in which a core tooth, a shaft and a commutator holder are assembled, and a commutator assembled in the commutator holder assembly. A commutator holder assembly and a commutator piece, comprising: a donut-shaped cylindrical space formed by a child piece and a shaft; and a donut-shaped cylindrical varistor having an electrode formed on an outer peripheral portion arranged in the donut-shaped cylindrical space. And a donut-shaped cylindrical varistor are assembled from one direction.

A commutator device for a small motor according to claim 5 of the present application is a commutator holder assembly in which a core tooth, a shaft, and a commutator holder are assembled, and a commutator assembled in the commutator holder assembly. A commutator holder assembly, a commutator piece, and a commutator holder, and a donut-shaped cylindrical space formed by the child piece and the shaft, and a commutator piece retainer having a donut-shaped cylindrical portion arranged in the donut-shaped cylindrical space. It is characterized in that the child piece presser foot is assembled from one direction.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the commutator device for a small motor according to claim 1 of the present invention, the commutator holder, riser and varistor constituting the commutator are assembled from one direction. At this time, the rotational direction positioning of the commutator holder is determined by the relationship between the commutator holder and the core teeth, and the varistor positioning is determined by the relationship between the commutator holder or the riser. It can be manufactured by assembly. Therefore, the man-hours can be significantly reduced, which is suitable for automatic assembly. And because the entire assembly is a structure that does not use soldering such as press fitting, crimping, and insertion,
The silver-containing solder, which was required in the past, is no longer necessary. Further, since it is a cylindrical varistor, unlike a plate-shaped varistor, it is possible to reduce cracking of the varistor due to press fitting.

In the commutator device for a small motor according to claim 2 of the present application, since the commutator holder, the riser and the cylindrical varistor are assembled from one direction, the assembly can be performed in the same manner as in claim 1 described above. The number of steps can be reduced, which is suitable for automatic assembly. Further, since the entire assembly is structured such that press-fitting, crimping, insertion, etc. are not used, the silver-containing solder which has been conventionally required is not necessary. Further, since it is a cylindrical varistor, unlike a plate-shaped varistor, it is possible to reduce cracking of the varistor due to press fitting. At this time, if the shape of the riser is bent and has a spring property, the contact portion between the riser and the varistor can be improved.

Further, the commutator device for a small motor according to claim 4 of the present invention is assembled to the commutator holder assembly in which the core teeth, the shaft and the commutator holder are assembled, and to the commutator holder assembly. A commutator holder assembly and a commutator, comprising a donut-shaped cylindrical space formed by a commutator piece and a shaft, and a donut-shaped cylindrical varistor having electrodes formed on an outer peripheral portion arranged in the donut-shaped cylindrical space. Since the piece and the donut-shaped cylindrical varistor are assembled from one direction, the man-hours can be largely reduced as in the first and second aspects, which is suitable for automatic assembly.

According to a fourth aspect of the present invention, as described in the fifth aspect, the commutator device for a small motor that does not use a varistor is used by using the commutator pressing member having the donut-shaped cylindrical portion arranged in the donut-shaped cylindrical space. Can be

[0018]

An embodiment of the present invention will be described below with reference to the drawings. The members, arrangements, and the like described below do not limit the present invention, and can be variously modified within the scope of the present invention.

FIG. 1 is an explanatory sectional view of a main part showing an embodiment of the invention according to claim 1. The commutator device S for a small motor shown in this example includes an armature shaft 6, a commutator holder 1, a riser 2, a varistor 3, and a varistor retainer 5.
And are the main components. The armature includes core teeth 7, and the shaft 6 is attached to the core teeth 7. Then, the commutator holder 1 is pressed into the shaft 6. In the core teeth 7 of this example, a convex portion (or concave portion) for positioning the commutator holder 1 in the rotational direction is formed on the contact surface with the commutator holder 1 (not shown).

The commutator holder 1 of this embodiment has a contact portion 11 with the core teeth 7, a holding portion 12 formed continuously with the contact portion 11, and a penetrating through the center of the commutator holder 1. Hole 13 and supporting recess 1 for varistor 3 and riser 2
4 is provided. Although not shown, the contact portion 11 of the commutator holder 1 is provided with a concave portion (or convex portion) for positioning the core teeth 7 in the rotational direction.

Support recess 14 for varistor 3 and riser 2
Are formed with concavo-convex portions 15 and 16 for positioning the varistor 3 in the rotational direction, and an arrangement groove 17 for the riser 2 is formed at a predetermined position on the outer peripheral side of the concavo-convex portions 15 and 16.

The riser 2 of this example is L-shaped,
An engagement groove 21 with the winding is formed on one end side.

The varistor 3 of this example has a cylindrical shape,
A through hole 31 to be assembled with the shaft 6 is formed at the center. The end surface on the side that contacts the commutator holder 1 is provided with the concavo-convex portions 32 and 33 that match the concavo-convex portions 15 and 16 of the commutator holder 1. Further, an engaging recess 34 that is inclined toward the through hole 31 is formed on the end surface on the side opposite to the uneven portions 32 and 33 for centering. A conductive layer 4 is formed on the outer peripheral surface of the varistor 3. The conductive layer 4 on the outer peripheral surface of the cylindrical varistor 3 is baked, plated,
It is formed by thermal spraying and acts as a commutator piece.

The varistor retainer 5 of this embodiment is a donut-shaped disc having a center hole 51. The center hole 51 is formed slightly smaller than the outer diameter of the shaft 6 so that it can be fixed to the shaft 6 by press fitting. Is formed in. Further, on one surface, that is, on the surface contacting the varistor 3, a recess 52 and a projection 53 are formed in conformity with the varistor 3 and the end surface shape, and the projection 53 is aligned with the engagement recess 34 of the varistor 3 for centering. Is formed as a protrusion inclined toward the shaft 6 side.

Next, an example of specific assembling will be described. In FIG. 1, the core teeth 7 and the shaft 6 are assembled in advance from one direction (that is, the A direction), and then the commutator holder 1, the riser 2, the varistor 3, and the varistor retainer 5 are press-fitted, crimped, inserted, etc. A commutator device S having the function of the varistor 3 is constructed. At this time, the positioning of the commutator holder 1 in the rotational direction is performed by the unevenness formed on the contact surfaces of the core teeth 7 and the commutator holder 1.

Further, the riser 2 is press-fitted into the commutator holder 1 or is clipped or the like to be fixed or semi-fixed (guided) to the commutator holder 1. Then, the varistor 3 is press-fitted into the commutator holder 1 and the riser 2 according to the positioning provided on the commutator holder 1, the contact between the riser 2 and the conductive layer 4 is secured, and the winding is wound around the riser 2 (not shown). The continuity with is secured.

Further, in this embodiment, the varistor retainer 5 is press-fitted onto the shaft 6 to prevent the varistor 3 from moving in the direction of the shaft 6 and to improve the reliability of electrical contact between the riser 2 and the varistor 3. .

As described above, according to the present embodiment, the electrode made of the conductive layer 4 is provided on the outer peripheral surface of the cylindrical varistor 3 and the outer peripheral surface of the cylindrical varistor 3 is press-fitted so that electrical contact and fixing of the varistor 3 are achieved. At the same time, a compressive stress is applied to the inside of the varistor 3 to prevent cracking due to tensile stress. Further, the structure can be assembled only by press-fitting and inserting from the direction A in the figure, and full automation can be realized.

In the method of fixing the commutator holder 1, as in the above embodiment, an example in which the core teeth 7 are formed with fitting holes or projections and the commutator holder 1 is formed with projections or fitting holes is shown. However, the present invention is not limited to this, and the commutator holder 1 may be assembled by press fitting into the shaft 6, or the commutator may be assembled by resin molding with the shaft 6 and the core teeth 7 assembled in advance. The holder 1 may be manufactured.

For fixing the riser 2, the shaft 6
Although it is press-fitted or press-fitted into the molded commutator holder 1 or semi-fixed, the riser 2 is press-fitted into the commutator holder 1 in advance, the shaft 6 is then press-fitted, and the core teeth 7 are assembled or rectified. After the child holder 1 and the core teeth 7 are assembled, the shaft 6 can be assembled and fixed.
Alternatively, the riser 2 may be insert-molded in the commutator holder 1 and then press-fitted into the core teeth 7 or the shaft 6 or caulked.

The positioning of the varistor 3 in the rotational direction was performed between the varistor 3 and the commutator holder 1 in the above embodiment, but the positioning irregularities on either the commutator holder 1 or the riser 2 are used. May be formed and positioned.

Although the varistor retainer 5 is used in the above embodiment, the varistor retainer 5 can be omitted if the varistor 3 can be fixed to the shaft 6 or the commutator holder 1 by adhesion or the like.

In the above embodiment, the commutator holder 1, the varistor retainer 5, and the varistor 3 have a centering structure in the direction of the shaft 6. However, if the coaxiality of the varistor 3 is sufficient, a simple structure such as a flat support may be used. It is possible to configure.

2 to 6 show an embodiment of the invention according to claim 2, FIG. 2 is an explanatory sectional view of a main part, FIG. 3 is a front view of a varistor used in FIG. 2, and FIG. 3 is a partial side view of FIG. 3, FIG. 5 is a side view of the riser used in FIG. 2, and FIG. 6 is a partial explanatory view showing another example of the riser. In this embodiment, the same members as those in the above embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In this example, the commutator holder assembly 9 and
Riser 2, cylindrical varistor 3, varistor retainer 5,
Is the main component.

The commutator holder assembly 9 has the shaft 6, the core teeth 7 and the commutator holder 1 assembled therein. The commutator holder is formed by integrally molding the shaft 6 press-fitted into the core teeth 7 with resin. Molding 1,
The commutator holder 1 is formed by resin-molding a single piece, and is press-fitted into a piece in which the shaft 6 and the core teeth 7 are assembled. Shaft 6 and core teeth 7 of this example
Positioning and the like in the rotational direction are performed as in the above embodiment.

Cylindrical varistor 3 of commutator holder 1 of this example
A cylindrical concave portion 14 is formed on the contact surface with and an engaging projection 16 is formed at a predetermined position of the cylindrical concave portion 14. The engagement protrusions 16 of this example are formed at three locations at equal intervals.
In addition, the commutator holder 1 is formed with the same number of insertion holes 18 as the risers 2 from the outer periphery toward the center. In this example, three insertion holes 18 are formed.

Then, the riser 2 for connecting the winding is fixed to the commutator holder assembly 9. Unlike the riser 2 of FIG. 1, the riser 2 of this example is composed of a linear plate body. The riser 2 of this example is fixed through the insertion hole 1
I am going through 8. The riser 2 can be fixed by press-fitting, caulking, etc., in addition to the above insertion.

As shown in FIGS. 3 and 4, the cylindrical varistor 3 of this example has a groove shape so as to be aligned with the engaging projection 16 formed on the surface which comes into contact with the commutator holder assembly 9 during assembly. The three engaging recesses 8 are radially formed at equal intervals. Therefore, the commutator holder assembly 1 is engaged with the commutator holder assembly 9 in relation to the engaging projections 16 of the commutator holder 1 to perform positioning in the rotational direction. In addition, as for the concavo-convex relationship between the commutator holder 1 and the cylindrical varistor 3 in positioning, which member the convex portion is formed on can be appropriately selected depending on the relationship with both members.

An electrode made of the conductive layer 4 is formed on the surface of the cylindrical varistor 3. The electrode made of the conductive layer 4 is used for baking silver alloy, baking other metal or alloy, plating, thermal spraying, chemical chemistry. Vapor deposition method (CVD), physical vapor deposition method (PV
D), coating and the like. Further, short-circuit portions 41 are formed between the conductive layers 4 at predetermined intervals. As a result, insulation is provided between the adjacent conductive layers.

Next, the assembling of the commutator device S having the above structure will be described. First, the commutator holder assembling body 9 will be described.
Attach riser 2 to. The riser 2 of this example is fixed by inserting it into the insertion hole 18 formed in the commutator holder 1, but the diameter of the insertion hole 18 is adjusted and press-fitted, or a groove is formed in the commutator holder 1. Then, it can also be performed by caulking or the like with this groove.

Next, the engaging projection 16 provided on the commutator holder 1 and the engaging recess 8 provided on the cylindrical varistor 3 are engaged with each other for positioning in the rotational direction, and the cylindrical varistor 3 is mounted on the shaft 6. insert. Then, by pressing the varistor retainer 5 into the shaft 6, the cylindrical varistor 3 is moved to the riser 2
To secure the electrical contact between the electrode made of the conductive layer 4 of the cylindrical varistor 3 and the riser 2 and to fix the varistor 3.

Next, the varistor retainer 5 is press-fitted. In this way, the varistor 3 is centered, and the commutator holder 1 and the varistor retainer 5 are assembled to the shaft 6 with the precision of parts.

The method of fixing the commutator holder 1 and the riser 2 may be, in addition to the above-described example, by press fitting, caulking, inserting, ultrasonic welding, or inserting an insert in advance when molding the commutator holder 1. Can be configured. In addition to press-fitting, fitting, and caulking from the direction A in FIG. 2, a part of the commutator holder 1 can be deformed and fixed using heat, ultrasonic vibration, or the like.

Further, the shape of the portion of the riser 2 and the electrode made of the conductive layer 4 of the cylindrical varistor 3 in contact with each other is shown in FIGS.
As shown in FIG. 5, in addition to providing unevenness on the contact portion, as shown in FIG. 5, a bent portion 22 is formed in the shape of the riser 2 to have spring properties and the conductive layer 4 of the cylindrical varistor 3 is provided.
It is possible to strengthen the contact with the electrode.

Further, as shown in FIG. 6, the shape of the riser 2 can be modified so that the contact between the cylindrical varistor 3 and the electrode made of the conductive layer 4 is improved. That is, A of FIG. 6 is an example in which the convex portion 23 is formed toward the varistor 3, and B is the projection 2 curved toward the varistor 3.
4 is an example in which C is formed, and C is a concave portion 2 which is curved in the opposite direction to B.
5 is an example in which No. 5 is formed.

Positioning of the cylindrical varistor 3 can be performed by changing both ends or one end face of the varistor 3 or the outer peripheral shape of the varistor 3 in addition to the above example. For example, as an example in which the outer peripheral shape of the varistor 3 is changed, it is possible to perform positioning by using a strained circle (so-called Omusubi shape) from the cylinder in the radial direction. At this time, the concave portion or the convex portion for positioning can be provided by setting either the commutator holder 1 or the varistor 3. The shape of the end of the varistor 3 is arbitrary as long as the electrode made of the conductive layer 4 can contact the riser 2 and does not short-circuit with the shaft 6 and does not short-circuit with other segments.

In this example, the varistor 3 is centered by the outer peripheral support and is assembled to the shaft 6 with the component accuracy of the commutator holder 1 and the varistor retainer 5.
It is also possible to make a convex or concave depression on the end face of and to fit or press the commutator holder 1 and the varistor presser 5. Furthermore, if the accuracy of the through hole 31 of the varistor 3 and the shaft 6 is sufficiently high and the coaxiality of the varistor 3 is high, centering need not be performed.

7 to 9 show an embodiment according to claims 4 and 5, FIG. 7 is an explanatory cross-sectional view of an essential part showing an embodiment of the invention according to claim 4, and FIG. 9 is an explanatory cross-sectional view of an essential part showing an embodiment of the present invention, and FIG. 9 is an explanatory cross-sectional view of an essential part showing another example of the embodiment of the present invention.

The inventions of claims 4 and 5 show an example in which the assembly is possible from the same direction regardless of the presence or absence of the varistor. 7 to 9, the same members and the like as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIGS. 7 and 9 show an example using a varistor. In the embodiment shown in FIG. 7, a commutator piece 10 and a shaft 6 which are assembled to a commutator holder assembly 9 are used to form a donut shape. The cylindrical space 10a is formed,
The donut-shaped cylindrical varistor 3 having electrodes formed on the outer periphery is assembled in the donut-shaped cylindrical space 10a, and in particular, the commutator holder assembly 9, the commutator piece 10, and the donut-shaped cylindrical varistor 3 are arranged in one direction. It has been assembled from.

That is, in the embodiment of FIG. 7, a groove 19 in the direction of the shaft 6 for attaching one end side of the commutator piece 10 to the commutator holder 1 constituting the commutator holder assembly 9 is formed. One end side of the commutator piece 10 is mounted in this groove 19. As a result, a donut-shaped cylindrical space 10a is formed between the commutator piece 10 and the shaft 6. A donut-shaped cylindrical varistor 3 having electrodes formed on the outer peripheral portion is mounted in the cylindrical space 10a, and a varistor retainer 5 is further attached. In this example, the commutator piece 10 is formed longer than the end surface of the varistor 3, and accordingly, the groove 54 is also formed in the varistor retainer 5.
Is formed, and the end of the commutator piece 10 is fitted in the groove 54. Accordingly, the commutator piece 10 can be fixed and the contact between the commutator piece 10 and the varistor 3 can be strengthened.

The embodiment shown in FIG. 9 shows an example in which the end of the commutator piece 10 on the varistor retainer 5 side and the end of the varistor 3 are formed at the same position. Even with such a configuration, it is possible to obtain the same effects as those of FIG. 7.

FIG. 8 shows an example in which a varistor is not used. Instead of the varistor 3, the varistor retainer 5 is used as a commutator one-side retainer 55, and this commutator one-side retainer 55 is press-fitted onto the shaft 6 to form a commutator. It fixes one piece. That is, the commutator half presser 55 of this example is the same as the varistor 3 shown in FIG.
It has a donut-shaped cylindrical portion 56 similar to. A through hole 57 is formed in this cylindrical portion. Other configurations and the like can be configured in the same manner as the above-mentioned respective embodiments and further by combining the above-mentioned respective embodiments.

[0055]

In the commutator device for a small motor according to the first aspect of the present invention, the commutator holder, the riser and the varistor constituting the commutator are assembled from one direction. Therefore, the man-hours can be significantly reduced, which is suitable for automatic assembly. Further, since the entire assembly is structured such that press-fitting, crimping, insertion, etc. are not used, the silver-containing solder which has been conventionally required is not necessary. Further, since it is a cylindrical varistor, unlike a plate-shaped varistor, it is possible to reduce cracking of the varistor due to press fitting. As described above, since it is possible to assemble from one direction without using solder, it is easy to assemble even on a high-speed manufacturing line.

In the commutator device for a small motor according to claim 2 of the present application, the commutator holder, the riser, and the cylindrical varistor are assembled from one direction, so that the commutator can be assembled in the same manner as in claim 1 described above. The number of steps can be reduced, which is suitable for automatic assembly. Further, since the entire assembly is structured such that press-fitting, crimping, insertion, etc. are not used, the silver-containing solder which has been conventionally required is not necessary. Also, since it is a cylindrical varistor, the assembly exerts a compressive force in the axial direction, so cracking due to tensile stress is unlikely to occur, and unlike a plate-shaped varistor, it is possible to reduce cracking of the varistor due to press fitting. . At this time, if the shape of the riser is bent and has a spring property, the contact portion between the riser and the varistor can be improved.

According to the fourth and fifth aspects of the invention, the commutator device can be made extremely easy to automate and the presence or absence of a varistor can be dealt with. Moreover, the same mounting method can be used with or without varistor. In the configuration of claim 4,
Compared to the case where a cylindrical varistor is used as a commutator, the conductor (mainly metal) that is applied or baked on the outer surface of the varistor is less likely to wear than the case where the cylindrical varistor is used as a commutator. It is possible to use weak (soft) metals. It is possible to use a soft material such as silver that has been mainly used for baking in the related art, and it is possible to provide a long-life commutator device with a built-in varistor by the conventional technology.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view of an essential part showing an embodiment of the invention according to claim 1.

FIG. 2 is an explanatory cross-sectional view of an essential part showing an embodiment of the invention according to claim 2;

FIG. 3 is a front view of the varistor used in FIG.

FIG. 4 is a partial side view of FIG. 3;

FIG. 5 is a side view of the riser used in FIG.

FIG. 6 is a partial explanatory view showing another example of the riser.

FIG. 7 is an explanatory cross-sectional view of a main part showing an embodiment of the invention according to claim 4;

FIG. 8 is an explanatory cross-sectional view of a main part showing an embodiment of the invention according to claim 5;

FIG. 9 is a cross-sectional explanatory view of essential parts showing another example of the embodiment of the invention according to claim 4;

[Explanation of symbols]

 1 commutator holder 2 riser 3 varistor 4 electrode 5 varistor presser 6 shaft 7 core teeth 9 commutator holder assembly 10 commutator piece 10a cylindrical space S commutator device for small motor

Claims (5)

[Claims] 1. An armature shaft, a commutator holder assembled by press fitting between the shaft, a riser engaged between the shaft and the commutator holder, and a press fit into the shaft. A varistor having a cylindrical shape and a conductive layer formed on the outer peripheral surface of the varistor, wherein the commutator holder, the riser and the varistor are assembled from one direction. The varistor is positioned in relation to the core teeth of the armature in a rotational direction, and the varistor is positioned in relation to the commutator holder or the riser and press-fitted onto the shaft and the riser to secure the contact between the riser and the conductive layer and to wind the riser. A commutator device for a small motor, characterized by ensuring electrical continuity with an attached winding. 2. A commutator holder assembly in which a shaft, core teeth and a commutator holder are assembled, a riser fixed to the commutator holder assembly, and the commutator holder assembly. And a commutator holder assembly, the riser and the varistor are assembled from one direction, and the cylindrical varistor is composed of a commutator holder assembly. It is rotationally positioned with the attachment body and inserted into the shaft, and then the varistor retainer is pressed into the shaft to push the cylindrical varistor in the direction of the riser to ensure electrical contact between the cylindrical varistor electrode and the riser. A commutator device for a small motor, which is characterized by fixing a varistor. 3. The commutator device for a small motor according to claim 2, wherein the shape of the riser is bent and has a spring property. 4. A commutator holder assembly in which a core tooth, a shaft, and a commutator holder are assembled, and a donut-shaped cylinder formed by a commutator piece and a shaft assembled in the commutator holder assembly. A doughnut-shaped cylindrical varistor in which an electrode is formed on an outer peripheral portion arranged in the donut-shaped cylindrical space, and the commutator holder assembly, the commutator piece, and the donut-shaped cylindrical varistor are assembled from one direction. A commutator device for a small motor, characterized by being attached. 5. A commutator holder assembly in which a core tooth, a shaft, and a commutator holder are assembled, and a donut-shaped cylinder formed by the commutator piece and the shaft assembled in the commutator holder assembly. A commutator holder having a space and a donut-shaped cylindrical portion arranged in the donut-shaped cylindrical space, wherein the commutator holder assembly, the commutator piece and the commutator holder are assembled from one direction. A commutator device for a small motor characterized by the following.