JP3691153B2 - Coreless motor - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a coreless motor, and more particularly to a coreless motor characterized in that a bearing closer to a commutator is substantially made of synthetic resin among two front and rear bearings that support a shaft.
[0002]
[Prior art]
In the conventional coreless motor, as shown in FIG. 5, among the two substantially front and rear bearings that support the shaft 2, the bearing 8 closer to the commutator and the collar 52 attached to the shaft 2. Between the two, a synthetic resin liner 9 was inserted for the purpose of reducing friction between the two. As a material for the bearing 8, iron-based or copper-based oil-impregnated metal has been used.
[0003]
The coreless motor is used as an incoming call notification device such as a pager (pager), and generally has a weight fixed eccentrically at the tip of the shaft 2 taken out of the casing of the motor.
[0004]
When this coreless motor is driven, the bearing 8 that is close to the commutator among the two substantially front and rear bearings that support the shaft 2 is placed in the thrust direction (the shaft 2 is connected to the casing of the motor) by the rotating eccentric weight. It turns out that the force that tries to pull out) works relatively strongly. On the other hand, it was found that the radial force acts relatively strongly on the other bearing due to the rotating eccentric weight. This is because the weight is fixed only to one end portion of the shaft 2.
[0005]
[Problems to be solved by the invention]
In particular, when the thrust force acts on the shaft 2, the friction between the bearing 8 and the collar 52 attached to the shaft 2 is reduced by the synthetic resin liner 9 as described above. A relatively strong friction is still generated between the metal bearing 8, the synthetic resin liner 9, and the bush 51. This immediately leads to the problem of motor energy loss.
[0006]
In addition, as long as the liner 9 has to be used, a part called the liner 9 is necessary, and a man-hour for inserting the liner 9 between the bearing 8 and the collar 52 through the shaft 2 is required. It was high. There is a strong desire to reduce the cost of coreless motors as much as possible.
[0007]
On the other hand, there is a problem of noise generated by the collision between the shaft 2 and the oil-impregnated metal bearing 8, that is, a rattling noise.
[0008]
Each of the above problems is closer to the side where the thrust force that tries to pull out the shaft 2 to the outside of the casing of the motor is relatively stronger than the side where the radial force acts relatively, that is, the commutator. It turned out to be a problem on the other bearing side.
[0009]
Accordingly, the present invention aims to solve the above-described problems, reduce friction and energy loss when the shaft 2 rotates, lower the rattling noise, and further reduce the cost of the coreless motor.
[0010]
[Means for Solving the Problems]
The above problem is that a stator is attached to the outer periphery of a substantially cylindrical magnet base fixed to the center of the casing, and bearings are attached to both ends of the magnet base, and a shaft is inserted through the bearing. In a coreless motor comprising a rotor portion in which a commutator and a cup are fixed to the shaft via a collar, and a brush elastically contacted with the commutator, of the substantially two front and rear bearings that support the shaft. This is achieved by using a coreless motor in which the bearing closer to the commutator is molded of synthetic resin and has a protrusion at a position facing the collar attached to the shaft.
[0011]
Further, according to the first aspect of the present invention, the bearing closer to the commutator is provided with a protruding portion facing a collar attached to the shaft.
[0012]
Further, according to claim 1, the collar is achieved by having a shape protruding from the end of the commutator base with respect to the bearing closer to the commutator.
[0013]
[Action]
When a motor is driven with a weight attached to the shaft, a thrust force acts on the shaft. At this time, the friction between the bearing made of the synthetic resin and the collar attached to the shaft is suppressed to a low level because the bearing is made of the synthetic resin, and as a result, the energy loss is reduced.
[0014]
Moreover, according to this synthetic resin bearing and shaft, the conventional rattling noise is reduced.
[0015]
Furthermore, compared to oil-impregnated metal, the bearings can be mass-produced by synthetic resin molding, so the cost is low. Since the bearing and the liner are integrated into one body and the conventional liner is not necessary, the cost is naturally low as the number of parts and man-hours decrease.
[0016]
【Example】
Next, examples of the present invention will be described with reference to the drawings. However, the present invention is not limited to these examples.
[0017]
1 and 2 show a first embodiment of the present invention. The present embodiment relates to a cup-type coreless motor. Regarding the internal configuration of this cup-type coreless motor, the stator 3 has a magnet 3 on the outer periphery of a cylindrical magnet base (metal house) 12 fixed to the casing 1. At the same time, both of the front and rear bearings 10 and 7 that support the shaft 2 are formed inside the both ends of the magnet base 12 and the bearing 7 closer to the commutator 5 is formed by injection molding of polyacetal resin, for example. The other side bearing 10 is made of iron-based metal and is inserted. The shafts 2 are inserted into the bearings 10 and 7, the commutator 5 and the cup 4 are fixed to the shaft 2 of the rotor portion, and the brush 60 attached to the brush base 6 inside the casing 1 is elastically contacted with the commutator 5. Become. The vibration generating unit is formed by inserting the shaft 2 of the cup-type coreless motor into a weight insertion port and attaching the weight eccentrically to the shaft 2 (not shown). A coil is wound around the cup 4.
[0018]
In the figure, reference numeral 14 denotes an end cap of the motor, reference numeral 15 denotes a lead wire, reference numeral 50 denotes a commutator segment, reference numeral 51 denotes a bush, reference numeral 52 denotes a mold plate, and reference numeral 21 denotes a shaft 2. The liner is shown. The commutator segment 50 is integrally provided when the mold plate 52 is molded, and the shaft 2 is inserted into the mold plate 52 via a bush 51. The end cap 14 is fitted to the rear portion of the casing 1, the lead wire 15 attached to the end cap 14 is wired to the brush 60, and the commutator segment 50 is wired to the coil winding of the cup 4.
[0019]
In the bearing 7 formed by molding the polyacetal resin, a portion facing the bush 51 is protruded to form a protruding portion 70.
[0020]
In the prior art, a liner is inserted between the bearing 7 and the bush 51. However, since the projection 70 is formed on the bearing 7 so as to project toward the bush 51, the projection 70 becomes a conventional liner. This is a polyacetal resin molding that is integral with the bearing 7. When a thrust force is applied to the shaft 2, friction between the synthetic resin bearing 7 and the bush 51, which is a collar attached to the shaft 2, causes the protrusion 70 of the bearing 7 to be made of synthetic resin. It is reduced by being, and energy loss is also reduced. In addition, although the structure which does not provide the protrusion part 70 is also possible, since it is a resin molding, it is the same as any structure on manufacture.
[0021]
Further, in this embodiment, between the shaft 2 and the synthetic resin bearing 7 having the projecting portion 70 facing the bush 51, the conventional rattling noise is reduced and the motor noise is reduced. It has been realized.
[0022]
Furthermore, since the bearing 7 having the protrusion 70 can be mass-produced by synthetic resin molding as compared with the oil-impregnated metal, the cost can be reduced, and the bearing 7 and the conventional liner are integrated into a single body. Therefore, a reduction in the number of parts and a reduction in the number of man-hours are realized.
[0023]
FIG. 3 shows a second embodiment of the present invention. According to the first embodiment, the friction between the bearing 7 made of synthetic resin and the bush 51 which is a collar attached to the shaft 2 is small. This is because the bearing 7 is a synthetic resin part. (Furthermore, according to the first embodiment, the protrusion 70 of the bearing 7 simulates the shape of a conventional liner.)
[0024]
A similar action can be realized by a shape in which the bush 51, which is a collar attached to the shaft 2, is protruded with respect to the bearing closer to the commutator. It is only necessary that the bearing 7 is a synthetic resin part.
[0025]
Therefore, in the second embodiment, the bearing 7 molded with the polyacetal resin has a protruding portion 70 at a portion facing the bush 51, and the protruding portion 53 is formed at a portion where the bush 51 faces the bearing 7. The configuration is as follows.
[0026]
That is, the protrusion 70 of the bearing 7 and the protrusion 53 of the bush 51 both imitate the shape of a conventional liner.
[0027]
FIG. 4 shows a third embodiment of the present invention. Although this embodiment is based on the same concept as the second embodiment described above, the magnet base 12 of the first and second embodiments is configured to have a large diameter on the bearing 7 side. The embodiment is a magnet base 13 having the same diameter over its entire length. For this reason, the bearing 71 is crowned at the end of the magnet base 13 and a protrusion 70 is provided at a portion facing the bush 51 of the bearing 71. Characterized by points. A protrusion 53 is also provided on the bush 51 side.
[0028]
Also in this embodiment, since the bearing 71 is made of a synthetic resin, the friction with the bush 51 is small. The protrusion 70 simulates the shape of a conventional liner.
[0029]
The present invention is not limited to the above-described embodiment, and the type of the synthetic resin material that forms the bearing closer to the commutator is arbitrary, and when the protrusion is formed on the bearing, the surface facing the bush is formed. A spherical shape may be used, and oil may be added to the bearing or the projecting portion during molding, or grease may be applied after molding. Further, the present invention can be applied not only to a coreless motor but also to a general small motor.
[0030]
【The invention's effect】
As described above, according to the present invention, a stator portion in which a magnet is attached to an outer peripheral portion of a substantially cylindrical magnet base fixed to a central portion of a casing, and bearings are attached to both ends of the magnet base, and a shaft is attached to the bearing. In a coreless motor comprising a rotor portion inserted through the collar and fixed with a commutator and a cup via a collar, and a brush elastically contacted with the commutator, two substantially front and rear bearings that support the shaft. The coreless motor is characterized in that the bearing closer to the commutator is molded of synthetic resin. In other words, the so-called conventional liner is incorporated by molding the bearing closer to the commutator with synthetic resin.
[0031]
As a result, the friction between the synthetic resin bearing and the collar attached to the shaft is further reduced, and energy loss is reduced, and the conventional rattling noise is reduced by this synthetic resin bearing. Yes. Compared to conventional oil-impregnated metal, the bearing can be mass-produced by synthetic resin molding, so that the cost is low and the liner is incorporated into the bearing, so that the conventional liner is unnecessary. Therefore, it has succeeded in reducing the manufacturing cost accompanying the reduction in the number of parts and the man-hours.
[Brief description of the drawings]
FIG. 1 is a partially cutaway sectional view of a first embodiment of the present invention.
FIG. 2 is a partially enlarged cross-sectional view of FIG.
FIG. 3 is a partially enlarged sectional view of a second embodiment of the present invention.
FIG. 4 is a partially enlarged cross-sectional view of a third embodiment of the present invention.
FIG. 5 is a partially enlarged sectional view of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Casing 10 Bearing 11 Liner 12 Magnet stand 13 Magnet stand 14 End cap 15 Lead wire 2 Shaft 3 Magnet 4 Cup 5 Commutator 50 Commutator segment 51 Bush 52 Mold plate 53 Protrusion part 6 Brush base 60 Brush 7 Bearing 70 Protrusion part 71 bearing

Claims (2)

A stator portion with a magnet attached to the outer periphery of a substantially cylindrical magnet base fixed to the center of the casing, and bearings are attached to both ends of the magnet base, and a shaft is inserted into the bearing so that a color is provided on the shaft. In a coreless motor comprising a rotor portion to which a commutator and a cup are fixed via a brush, and a brush elastically contacted with the commutator,
Of the two substantially front and rear bearings that support the shaft, the bearing closer to the commutator is molded of synthetic resin and has a protrusion at a position facing the collar attached to the shaft. Coreless motor.  The coreless motor according to claim 1, wherein the collar has a shape protruding from an end of the commutator base with respect to a bearing closer to the commutator.

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