JPH0729659A - Commutator for micro-motor - Google Patents

Abstract

PURPOSE:To subminiaturize the outer diameter of a commutator and attain an extension in life and a reduction in cost by interposing and integrating an insulating adhesive having a fine spacer included therein between a motor rotating shaft and a commutator segment. CONSTITUTION:An insulating adhesive 3 in which uniform silica particles 4 having a diameter of 1-several mum are applied to the surface of the rotating shaft 2 of a motor, and three commutator segments 10 are arranged on this surface to be axially symmetrical at 120 deg., and pressed and adhered thereto. Consequently, a commutator 1 substantially has the total thickness of the rotating shaft 2 of the motor and the segments 10, and subminiaturization or a diameter of 0.5mm can be realized. Thus, peripheral speed is minimized to reduce the wear of the segments 10 and extend the life, and the amount of a noble metal contact material to be used is also reduced to reduce the cost. Further, the frictional loss with a brush elastically making contact therewith is also reduced, and output loss can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a commutator for a micro motor having an extremely small outer diameter.

[0002]

2. Description of the Related Art A conventional small-sized motor commutator with a brush has a commutator segment as a press metal part integrally assembled on a rotary shaft of a motor by synthetic resin molding. Has a brush for power feeding. The commutator segment has an arc shape, and a plurality of commutator segments are arranged in a cylindrical shape and a slit is formed between each commutator segment. In a small motor, it is general that the three arc-shaped commutator segments are arranged in 120-degree axial symmetry. The current applied to the brushes is sequentially distributed to each of the sharing coils through each commutator segment of the rotating commutator. Such a commutator is
It is widely used in brushed motors, and such motors are also used as vibrator motors for pagers, shoulder taps, and the like.

[0003]

Generally, a small motor is required to have a small moment of inertia in order to obtain a large starting torque, and attempts have been made to reduce the weight of the rotor and the radius of gyration. There is. For example, a cup-type coreless motor satisfies the above requirements, has no rotating iron core, and therefore has a small radius of a rotor (a cup formed by winding an armature coil).

Further, in a commutator of a small motor, it is required to reduce the radius of gyration of the commutator, but this has the following problems. First
Since the commutator segment is integrally assembled to the rotary shaft of the motor by synthetic resin molding, there is a limit to reducing the diameter, and the diameter is about 2 mm. Secondly, if the radius of rotation of the commutator is large, the peripheral speed naturally increases, the wear of the commutator becomes severe, and the life of the commutator becomes short. Thirdly, a costly noble metal contact material is used as the material of the commutator segment, but if the radius of the commutator is large, the amount of its use will be ridiculous. Fourthly, if the radius of the commutator is large, the friction loss between the commutator and the brush elastically contacting the commutator is large, and 10% of the output is lost.

As described above, since the commutator segment is integrally assembled with the rotary shaft of the motor by the synthetic resin molding, a constant thickness is provided between the commutator segment and the rotary shaft of the motor. From the point of view of its function, it can be said that it is a synthetic resin base that it has.

If the radius of gyration of the commutator, which is the first problem, can be reduced, the peripheral speed will be reduced, the wear of the commutator will be reduced, and the service life will be extended. In addition, the amount of expensive noble metal contact materials used is reduced, leading to cost reduction. In addition, the friction loss between the brush that is elastically contacting the commutator and the output loss can be prevented. The present invention aims to solve such a problem.

[0007]

The above-mentioned problems are solved by interposing an insulating adhesive containing minute spacers between the rotating shaft of the motor and the commutator segment.
This is achieved by integrating the rotating shaft of the motor and the commutator segment to form a commutator.

[0008]

When the rotary shaft of the motor and the commutator segment are bonded together with an adhesive, it can be said to be the above-mentioned synthetic resin base, which is directly integrated without interposing unnecessary parts in terms of function. Will be changed. For this reason,
The outer diameter of the commutator can be minimized. At this time, a minute spacer exists between the rotating shaft of the motor and the commutator segment, and since the adhesive enters into the gap corresponding to the thickness of the spacer and is solidified, the thickness of the adhesive layer is The outer diameter of the commutator is minimized as much as the diameter of the spacer.

[0009]

Embodiments of the present invention will now be described with reference to the drawings, but the present invention is not limited to these embodiments.

1 to 3 show a commutator 1 according to a first embodiment of the present invention, in which silica particles 4 (SiO2) having a uniform diameter are mixed on the surface of a rotary shaft 2 of a motor. An adhesive 3 having an insulating property is applied, and the adhesive 3
The three commutator segments 10 are arranged and bonded in a 120-degree axial symmetry so as to be pressed against the surface. The silica particles 4 may have a diameter of 1 to several microns, and the silica particles 4 in a volume ratio of about several percent may be mixed in the adhesive 3 in advance. In the figure, reference numeral 11 is a terminal for soldering the lead wire of the coil, and reference numeral 12 is a slit between the commutator segments 10.

Since the silica particles 4 having a uniform diameter are mixed in the adhesive 3, when the commutator segment 10 is pressed against the surface of the adhesive 3 to be bonded,
As shown in FIG. 3, between the rotary shaft 2 of the motor and the commutator segment 10, the adhesive 3 having a thickness of at least one diameter of the silica particles 4 (arrow A) is used. Layers will be formed.

As a result, the thickness of the layer of the adhesive 3 can be almost ignored, and the commutator 1 of this embodiment is substantially the total of the rotary shaft 2 of the motor and the commutator segment 10. Since it has a thickness of 2 mm, and there are unnecessary parts in terms of the function that should be called a synthetic resin base in the past, it was possible to reduce the size to a minimum of 2 mm. However, in this embodiment, the minimization as much as possible is realized, and it is 0.5.
I was able to get a millimeter diameter.

Since the radius of gyration of the commutator 1 is minimized, the peripheral speed is reduced, the wear of the commutator segment 10 is reduced, the life of the commutator segment 10 is extended, and the commutator segment 10 is extended. The amount of expensive noble metal contact material used for the data segment 10 is reduced, the cost is successfully reduced, and the friction loss between the brush (not shown) elastically contacting the commutator 1 is reduced. It was possible to obtain the effect that the output loss was reduced.

Next, a second embodiment of the present invention will be described with reference to an enlarged partial sectional view of FIG. In the above-described first embodiment, the silica particles 4 having a uniform diameter are used as the minute spacers mixed in the adhesive, and the silica particles 4 are considered to be substantially spherical, In addition to such a spherical body, various kinds and minute spacers of various shapes can be arbitrarily selected. For example, in the present embodiment, a fine acrylic cylinder 5 is mixed in the adhesive 3 and the rotary shaft 2 of the motor is
The adhesive 3 in which the acrylic cylinder 5 is mixed is applied to the surface of, and the commutator segment 10 is adhered so as to be pressed against the surface of the adhesive 3. That is, a layer of the adhesive 3 having a thickness (arrow A) of at least one diameter of the acrylic cylinder 5 is formed between the rotary shaft 2 of the motor and the commutator segment 10. Become.

Next, a third embodiment of the present invention will be described with reference to an enlarged partial sectional view of FIG. As is apparent from the above-described second embodiment, the minute spacers mixed in the adhesive can be arbitrarily selected. In this embodiment, the short fiber 6 of glass fiber is mixed in the adhesive 3 and An adhesive 3 mixed with the short fibers 6 is applied to the surface of the rotary shaft 2, and a commutator segment 10 is adhered so as to be pressed against the surface of the adhesive 3. The short fibers 6 may be present in the adhesive 3 and overlap each other. In FIG.
An example in which a layer of the adhesive 3 having a thickness of two short fibers 6 (arrow B) is formed between the rotating shaft 2 of the motor and the commutator segment 10 was taken. .

Next, a fourth embodiment of the present invention will be described with reference to an enlarged partial sectional view of FIG. Similarly, in the present embodiment, the crushed particles 7 obtained by sintering sludge and uniformly crushed are mixed in the adhesive 3, and the adhesive 3 mixed with the crushed particles 7 is mixed on the surface of the rotary shaft 2 of the motor. The commutator segment 10 is adhered so that it is applied and pressed against the adhesive 3 surface. That is, between the rotating shaft 2 of the motor and the commutator segment 10, a layer of the adhesive 3 having a thickness of at least one diameter of the crushed particles 7 (arrow A) is formed. .

By the way, when the commutator segment 10 is adhered to the surface of the rotary shaft 2 of the motor, the commutator segment 10 is adhered to a predetermined position on the rotary shaft 2 of the motor by using a jig so that the commutator 1 is attached. In addition to the configuration, various configuration methods can be adopted. Fifth of the present invention
The embodiment is one of the particularly effective examples.

This embodiment will be described with reference to FIGS. 7 and 8. Cylindrical commutator segment support 13
Has three slits 12 engraved at a position 120 degrees axisymmetric from the center to one end, and two parallel ring-shaped grooves 14 crossing the slit 12 are dug in the center of the cylinder. The terminal 11 is formed at one end of the commutator segment support 13. Here, from the front of the slit 12, the rotating shaft 2 of the motor coated with the insulating adhesive 3 mixed with the silica particles 4 having a uniform diameter is press-fitted into the cylindrical commutator segment support 13, When the tip of the rotary shaft 2 of the motor reaches the first ring-shaped groove 14, the press-fitting is stopped to fix the adhesive, and thereafter, as shown in FIG. 8, the commutator segment support is performed along the first ring-shaped groove 14. The commutator 1 is configured so that the body 13 is cut.

As a result, significant labor saving is realized as compared with the case where three independent commutator segments 10 are bonded to the rotary shaft 2 of the motor, and the space between the three commutator segments 10 is increased. The slits 12 are arranged so that the intervals between them can be accurately obtained.

In the above-mentioned fifth embodiment, it is considered that the commutator segment support 13 is cut along the ring-shaped groove 14, and so to speak, the slit 12 is formed later. Other than that, various configuration methods can be adopted. As shown in FIG. 9, the sixth embodiment of the present invention is a motor in which a cylindrical commutator segment 16 is coated with an adhesive 3 having an insulating property in which a fine acrylic cylinder 5 having a uniform diameter is mixed. The rotary shaft 2 is press-fitted, and the cut portion 15 is engraved so as to form the three slits 12 at the predetermined 120-degree axially symmetrical positions of the cylindrical commutator segment 16. The cut portion 15 may be formed by burning with a laser beam, cutting with a blade, or the like.

The seventh embodiment of the present invention, as shown in FIG. 10, has a cylindrical commutator segment 1
The surface of 6 is covered with a mask 8 by surface coating except for the area where slits are formed, and a fine acrylic cylinder 5 having a uniform diameter is mixed in the cylindrical commutator segment 16. The rotating shaft 2 of the motor coated with the adhesive 3 having an insulating property is press-fitted, and the cylindrical commutator segment 16 is etched with strong acid to corrode the portion 1.
7 is formed, and the corroded portion 17 serves as the slit 12,
The commutator 1 is configured.

By the way, since the commutator 1 generally rotates at a high speed, there is a problem that when the brush elastically contacts the commutator 1, wear occurs at both contact portions, and a wear groove is formed in the commutator 1. Of course, abrasion also occurs on the brush side. The abrasion of the brush causes the elastic contact force of the commutator to be weakened. Further, when the brush passes between the slits of the commutator 1, sparks are generated due to the induction current of the coil, which also promotes wear. In particular, the influence of wear debris is great, and the powder is accumulated between the slits 12 of the commutator 1 to form the commutator segment 10
This causes a short circuit between them, the motor does not rotate, or the motor adheres to the entire surface of the power feeding surface of the commutator 1 to increase the resistance between the brush and the commutator 1. It has also been pointed out that noise is generated due to these synergistic effects. Here, the essential problem is that there is a step like the slit 12 between the commutator segments 10, and the step called the slit 12 (a discontinuous portion on the cylindrical curved surface) causes the bounce of the brush,
Further, it also serves as a starting point of wear, and wear powder is accumulated in the slits 12, resulting in a short-like state between the commutators 10. This result has a significant effect on shortening the life of the motor.

This problem can be solved simply by filling the slits 12 between the segments 10 of the commutator with an arbitrary insulating material so as to form the same surface as the outer peripheral surface of the commutator 1. That is, since the slit 12 is filled with an arbitrary insulating material so as to form the same surface as the outer peripheral surface of the commutator 1, the outer peripheral surface of the commutator 1 has a uniform cylindrical shape without a step due to the slit 12. The contact between the commutator and the brush is extremely smooth. Therefore, the brush does not bounce, the occurrence of sparks is reduced, and there is no part that is the starting point of wear, so the wear of the commutator 1 and the brush is reduced, and since there is no step in the slit 12, wear powder is accumulated. Therefore, the commutator segments 10 are not short-circuited. Also, the lubrication performance is improved and the noise is low.

An eighth embodiment described below applies this configuration to the present invention. As shown in FIG. 11, a slightly larger amount of insulating adhesive 3 mixed with silica particles 4 having a uniform diameter is applied to the surface of the rotary shaft 2 of the motor,
The three commutator segments 10 are arranged and bonded to each other so as to be pressed against the three surfaces of the adhesive so as to be axially symmetrical with respect to 120 degrees. At this time, the excess adhesive 3 is pushed into the slits 12 between the three commutator segments 10, and the slits 12 are filled up to finish. If necessary, the adhesive 3 part of the slit 12 may be sanded so that the outer peripheral surface of the commutator 1 becomes uniform.

In this manner, the outer peripheral surface of the commutator 1 has a uniform cylindrical shape with no step due to the slit 12 because the adhesive 3 fills the slit 12, and the contact between the commutator 1 and the brush is extremely high. It will be done smoothly.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and when an adhesive is used to intervene, the adhesive is not applied to the inside of the rotating shaft of the motor or the commutator segment, but the rotation of the motor is not. It can also be realized by filling the gap between the shaft and the commutator segment with any synthetic resin material having an insulating property, and this is also included in the concept of the adhesive of the present invention. The type of adhesive is also arbitrary. Further, the type, shape, size, etc. of the spacer can be freely selected. It is also possible to mix a plurality of spacers of different types. Further, the type of motor using the commutator according to the present invention and the field of use thereof are not particularly limited.

[0027]

As described above, according to the present invention, since the commutator segment is integrally assembled with the rotary shaft of the motor by the synthetic resin molding, the diameter cannot be reduced.
In order to solve the problems that the peripheral speed of the commutator is high, the service life is short, the amount of expensive precious metal contact material used is large, and the friction loss between the brush and the brush is large. An insulating adhesive mixed with a minute spacer is interposed between the segment and
The rotating shaft of the motor and the commutator segment are integrated to form a commutator for ultra-small motors.

As a result, the outer diameter of the commutator was successfully minimized, the peripheral speed was reduced, the wear of the commutator was reduced, and the life was extended. In addition, the amount of high-cost precious metal contact material used was reduced, and the cost could be reduced. In addition, the friction loss between the brush elastically contacting the commutator was reduced and the output loss could be prevented. Thus, the present invention successfully achieves the intended purpose.

[Brief description of drawings]

FIG. 1 is a perspective view of a first embodiment.

FIG. 2 is an enlarged sectional view of a part of the embodiment.

FIG. 3 is an enlarged partial sectional view of the embodiment.

FIG. 4 is an enlarged partial sectional view of a second embodiment.

FIG. 5 is an enlarged partial sectional view of a third embodiment.

FIG. 6 is an enlarged partial sectional view of a fourth embodiment.

FIG. 7 is a perspective view of the fifth embodiment during manufacturing.

FIG. 8 is an enlarged partial sectional view of the embodiment.

FIG. 9 is a sectional view of a sixth embodiment.

FIG. 10 is a sectional view of a seventh embodiment.

FIG. 11 is a sectional view of an eighth embodiment.

[Explanation of symbols]

 1 commutator 10 commutator segment 11 terminal 12 slit 13 commutator segment support 14 ring-shaped groove 15 cut part 16 commutator segment 17 corroded part 2 rotating shaft 3 adhesive 30 filling part 4 silica particle 5 acrylic cylinder 6 short Fiber 7 Crushed particles 8 Mask

Claims (1)

[Claims] 1. A rotary shaft of a motor and a commutator segment are integrated with each other by interposing an insulating adhesive mixed with minute spacers between the rotary shaft of the motor and the commutator segment. , A commutator for micro motors.