JP3380442B2 - Small DC motor with improved commutation - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a small direct current motor used as a silent call means of a mobile communication device, and more particularly to an improvement of commutation characteristics for a long life.

[0002]

2. Description of the Related Art Conventionally, there is a small DC motor, particularly a small DC motor having a commutator equipped with a precious metal commutation device, in which a lubricating grease is applied to a commutator or a brush in order to prolong the service life. As the lubricating grease, an ester synthetic oil is used as a base oil and a thickening agent made of metallic soap is mixed.

[0003]

In the lubricating grease described above, an ester synthetic oil, especially a diester oil, easily evaporates, and a thickener is contained in a considerably large amount in order to maintain the form as grease. Those using this diester-based synthetic oil have temperature dependence, and when used in precious metal rectifiers, they have low resistance at high temperatures and good rectification characteristics, but when the temperature decreases, the viscosity of the base oil decreases. When the brush pressure is low due to the solidification of the thickener itself, the rectifying characteristics are impaired. Further, the ester type has a relatively low evaporation temperature, and thus the thickener itself is apt to solidify over a long period of time, so that it is necessary to give sufficient consideration to storage. Therefore, it is diluted with an organic solvent and the thickener itself is dispersed before use. On the other hand, the olefin synthetic oil has a relatively high evaporation temperature and is stable for a long period of time, but the brush pressure needs to be slightly higher than that of the ester type oil, and brake loss is likely to occur.

The object of the present invention is to improve the rectification characteristics by skillfully incorporating the merits of each of the ester-based and olefin-based synthetic oils and skillfully incorporating the merits of the synthetic oil, and to obtain a long life of the noble metal rectifier. It aims to reduce the cost by reducing the amount of parts used.

[0005]

[Means for Solving the Problems] To solve such a problem, it is possible to use an appropriate mixture of ester-based and olefin-based synthetic oils, and the advantages of the ester-based and olefin-based ones can be exhibited. become.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, as described in claim 1, a rotor (having a armature coil (3a, 3b, 3c) in a housing (H) composed of a case (8) and a bracket (1) ( 3) is arranged so that electric power is supplied to the armature coil of the rotor through a rectifier composed of a commutator (5) and a brush (7), and a magnet (6) is exposed to the rotor through a gap. In a small DC motor, the commutator as a part of the commutator is a surface
Nickel-underlying gold plating is applied to the rectifier , and the rectifier is composed of a mixed synthetic oil of ester (X) and olefin (Y), and the mixing ratio (X) is 60 wt% or more, (Y).
To 0.5 wt% to 35 wt% and increase the balance
A lubricant (OG) composed of a carburizing agent may be included. By doing so, the respective advantages of the ester type (X) and the olefin type (Y) can be exhibited, the rectifying characteristics can be improved , and the lubricant can flow out with a small amount of thickener.
Can be prevented and a long life can be obtained.

Further, as described in claim 2, the increase
The scavenger is a metallic soap, and the content ratio as the balance to the total amount of the ester type (X) and the olefin type (Y) is
The content of 0.1 wt% to 5 wt% is preferable. By doing so, the contact reliability is further improved.

[0008] And, as for these, specifically, the rotor (3) has a plurality of air-core armature coils.
(3a, 3b, 3c) constitutes a flat plate commutator
The lubricant is placed on the back side of the printed wiring board (C).
Is applied to the brush sliding contact part on the front side of this printed wiring board.
Cage and fine stainless steel shaft on the bracket (1)
One end of (2) is fixed and this bracket is further forward
The magnet that drives the rotor through the air gap in the axial direction
Mounted, the rotor is rotatably mounted on the shaft,
The other end of the shaft is received by the case (8),
Forward with the pressing force of the brush (7) placed inside the magnet
Good to you to those brought into sliding contact with serial rotor case side.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A flat coreless vibration motor will be described as a structure of an embodiment of the present invention. As shown in FIG. 1, a shaft holder 1a which is integrally erected at the center of a bracket 1 which constitutes a part of a housing H. The fine stainless steel shaft 2 is fixed by press-fitting one end through
A rotor 3 eccentric from the open end is rotatably mounted on the shaft 2. Specifically, the eccentric rotor 3 includes three air-core armature coils 3a and 3b as shown in FIG.
And 3c are flat plate type commutator 5 (hereinafter referred to as flat plate
About 6 on the back side of the printed wiring board C that constitutes the data 5).
The air-core armature coils are placed on one side at a pitch of 0 degree, and these air-core armature coils are bent toward the magnet side in the axial direction on the outer circumference of the rotor 3 in order to increase the effective conductor length and the movement amount of the center of gravity. It is wound. The rotor 3 is further integrally formed with a low density slidable resin J1 containing potassium titanate whiskers and having a specific gravity of 1.6 or less as a base material such as polyamide so as to form a bearing hole 4 in the center. The bracket 1 has N and S facing the rotor 3 with a gap.
A ring-shaped magnet 6 made of a wet-processed ferrite which is alternately magnetized with an opening angle of 90 degrees is placed.
A pair of brushes 7, 7 are planted inside the plate at an opening angle of 90 ° so that they are brought into sliding contact with the front side of the printed wiring board C constituting the flat plate commutator 5 with an appropriate pressing force. Flat plate community
The surface of the printed wiring board C that constitutes the heater 5 is in sliding contact with the brush on the front side, and is plated with gold having a thickness of 0.5 μm on a nickel base, and is characterized by the characteristics of the ester (X) and olefin (Y) characteristics of the present invention. A lubricant OG made of mixed synthetic oil is applied. The lubricant made of this mixed synthetic oil has a compounding ratio of (X) 8
3w based on 0wt% and (Y) 15wt%
It contains a thickener consisting of about t% lithium soap. This 3 wt% thickener helps prevent oil spills.

On the other hand, a case 8 constituting the other part of the housing
Has a tapered through hole 8a in which the other end of the thin stainless steel shaft 2 is mounted, and the periphery of the through hole 8a is crushed to be a thin film. P is attached via glue N.
The eccentric rotor 3 is brought into sliding contact with the polyester film P by the pressing force of the pair of brushes 7, 7 via the bank portion 3d.
Further, a groove V concentric with the shaft is provided, and this groove V
Grease G is embedded as a lubricant in the. It is preferable that the grease G has a silencing function without contact failure, but the above-mentioned lubricant OG can also be used. In this way, there is no problem even if the lubricant OG goes to the front side of the printed wiring board C that constitutes the flat plate commutator 5 .
As described above, the rotor 3 is constantly urged toward the case 8 and is rotatably pressed by the polyester film P.
There is no risk of moving to the case 8 side and hitting it, and it is possible to stably support the rotation without making the rotation position consistent by keeping the gap constant, and the grease G or OG as a lubricant is held for a long time by the groove V. Will be. In this case, the groove may be V-shaped for generating dynamic pressure. With this configuration, the rotor 3 that has been prepared in advance
This can also be assembled by simply fitting it into the previously prepared bracket 1 from the open end of the shaft 2, covering the case 8 and caulking the outer periphery of the bracket 1 with the opening edge 8b.

Further, in order to form the recess for receiving the other end of the shaft 2 so as to function the insulation and the slidability, the case 8 for receiving the shaft 2 as shown in the schematic cross section of the main part of FIG. Is formed to be slightly larger than the shaft 2, and the other end of the shaft 2 is inserted into the through hole T by half through the glued polyester film P1 arranged around. Good. Polyester film P1 with glue in this case
It is preferable to crush the periphery of the through hole T of the case 8 and attach the above-mentioned polyester film P1 with the glue so that the thickness of the motor itself and the voids are not sacrificed by the thickness of the. In this way, a structure that maintains insulation and slidability can be obtained without sacrificing thinness.
The operating principle of such a motor is known, for example, in Japanese Patent Application No. 63-1111868 previously disclosed by the present applicant, and therefore its explanation is omitted here.

FIG. 4 shows the state of the rectified waveform when the flat coreless vibration motor in this embodiment is rotated at 6000 rpm for several tens of hours (equivalent to a life of 10 years or more). It can be seen that proper rectification is maintained.

Although the optimum component of the lubricant OG has been shown, (X) is 60 wt% or more and (Y) is 0.
It is preferable that the content is 5 wt% to 35 wt% and the balance is composed of a thickener.

The above embodiment has been described as a shaft-fixed type, which is advantageous in terms of cost, but it is needless to say that it can be used for a shaft-rotating type and can be used not only for a vibration motor but also for a normal-rotating type motor. Further, in the above embodiment, the one using the flat plate commutator is shown, but it is needless to say that it can be applied to the cylindrical commutator.

[0015]

As described above, according to the present invention, the straightening device is made to contain the lubricant composed of the mixed synthetic oil of the ester type (X) and the olefin type (Y). The disadvantages of X) and the olefin (Y) are compensated for, and the rectifying characteristics are improved, and a long life of the rectifying device is obtained by the lubricating action.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts of an embodiment of a flat coreless vibration motor of the present invention.

FIG. 2 is a plan view of a main part of an eccentric rotor according to the embodiment.

FIG. 3 is a cross-sectional view of a main part of a modified example of the same embodiment.

FIG. 4 is an explanatory diagram of a state of a rectified waveform after a life test of the example.

[Explanation of symbols]

1, 11 ... Bracket 2 ... Shaft 3 ... Eccentric rotor 4 ... Bearing hole 5 ... Commutator 6 ... Magnet 7 ... Brush 8 ... Case P ... Polyester film P1 ... Polyester film V with glue V Groove J1 Resin forming rotor OG Lubricant C Printed wiring board

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-60-55843 (JP, A) JP-A-5-76158 (JP, A) JP-A-8-266007 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H02K 13/00-13/14 H02K 23/00-23/68 H02K ^7/ 00-7/20

Claims (3)

(57) [Claims] 1. An armature coil (3a, 3b, 3 ) in a housing (H) consisting of a case (8) and a bracket (1).
arranged rotor (3) having a c), the conductive of the rotor
Do not use commutator (5) and brush (7) for armature coil.
In a small DC motor in which electric power is supplied through a rectifying device and a magnet (6) faces the rotor through an air gap, the commutation device is provided as a part of the rectifying device.
The surface of the rectifier is gold-plated with nickel undercoat, and the rectifier is composed of a mixed synthetic oil of ester type (X) and olefin type (Y), and the mixing ratio (X) is 60 wt% or less.
Above, (Y) 0.5wt% ~ 35wt%, and the remaining
A small direct current motor with improved commutation that contains a lubricant (OG) whose part is composed of a thickener. 2. The thickener is a metallic soap
As the balance, ester type (X) and olefin type (Y)
The small DC motor with improved commutation according to claim 1, wherein the content ratio is 0.1 wt% to 5 wt% with respect to the total amount . 3. The rotor (3) comprises a plurality of air-core armatures.
The coils (3a, 3b, 3c) are made into a flat plate type commutator.
It is placed on the back side of the printed wiring board (C) to be formed.
In addition, the lubricant is brush-contacted on the front side of this printed wiring board.
It is applied to the part, and the bracket (1) is
With one end of the stainless steel shaft (2) fixed, this bracket
The rotor is further driven by an axial gap.
A magnet is placed to rotate the rotor around the shaft.
It is mounted freely and the other end of the shaft is received by the case (8).
Brushes that are stopped and placed inside the magnet
A small direct current motor with improved commutation according to claim 1 or 2 , wherein the rotor is brought into sliding contact with the case side by the pressing force of (7) .