JPS6231345A - Miniature motor - Google Patents

Abstract

PURPOSE:To prevent not only the abnormal abrasion and welding to the slide contact face but the fretting damage thereby by impregnating the atmosphere inside a motor case with p-menthanol. CONSTITUTION:At a portion inside a motor case 20, e.g., close tu a brush slide 3 on a bracket 14, the member inpregnated with p-menthanol, e.g., a feltr16, is contactingly provided by means of securing with an adhesive or fixing by pressure. At the atmospheric temperature this p-menthanol is vaporized so that inside a motor case 20 it may be constituted that the ambient atmosphere is of p-menthanol. Thus, since the p-menthanol is adsorbed into the surface of the brush 13 and commutator segment, the lubricating action works so well that not only the abnormal abrasion and welding to the slide contact face but the fretting damage thereby can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a small motor used for driving a tape in, for example, a tape recorder or a video tape recorder.

Conventional technology To explain this using an example of a small motor that has the highest number of contact openings and closings,
Generally speaking, there are two types of brushes used in small motors. One is an elastic conductive material 1. For example, copper
Precious metal alloys (e.g. Au, Pd, PL
, Ag, Cu, etc., and their alloys) are clad or joined to a part of a thin plate or wire by spot welding, and the other is a part of the thin plate or wire mentioned above. A sintered carbon brush (for example, carbon, Ag carbon, Cu carbon, AgCu carbon, and those materials mixed with SiC*MQs, PB, epoxy resin, etc.) as a conductive adhesive. However, in small motors with these brushes, the brush sliding part vibrates unnecessarily when the commutator rotates, which causes the commutator of the brush sliding part to vibrate unnecessarily.・Abnormal welding occurs on the contact surface with the segment, and foreign matter that promotes the abnormal phenomenon called blackening (a mixture of carbon and sliding abrasion powder generated between the brush and the commutator segment) accompanying the generation of sparks. Problems that often occur,
becomes. An example of a brush for a small motor is one in which a brush sliding portion that comes into contact with a commutator segment is integrally formed with a brush base that is supported by support means provided on a lid of a motor case or the like. The state of contact between such a brush and the commutator segment is shown in FIG.

In FIG. 4, a bent brush sliding portion 3 extends from a brush base 2 supported by a brush support means 1. The brush base 2 and the brush sliding part themselves have elasticity and are in contact with the commutator segment 4 in a pressed state. This pressing force can be set to a required value by appropriately selecting the bending angle between the brush base 2 and the brush sliding portion 3. Further, the commutator segment 4 is fixed to the motor rotating shaft 6 via the commutator base 5, and rotates with the rotation of the motor.

Problems to be Solved by the Invention In this way, the commutator segments 4 that are in contact with each other
Electric sparks are generated from the brush sliding part 3 during rectification and due to intermittent contact points, and the generation of these electric sparks causes electrical noise, wear and welding of the commutator segment 4 and the brush sliding part 3. An inconvenient situation may occur, such as the occurrence of

For example, if welding occurs at the position where it starts to make contact with the commutator segment 4 and at the position where it leaves (section a in Fig. 4),
This welded material scrapes and damages the surface of the commutator segment 4, and furthermore, chips generated by this scraping accumulate in the gap between adjacent commutator segments 4 (section b in Fig. 4). Therefore, conduction occurs between the commutator segments, resulting in unstable rotation.

For example, if the surface roughness of the commutator segment surface becomes rough due to wear and tear, this may cause brush vibrations, promoting the generation of electrical sparks, further progressing wear, and causing abnormal wear, electrical noise, etc. The performance of the motor itself may deteriorate due to deviations in the commutation position.

Note that electric sparks are most often generated at the contact surface a of the brush sliding portion 3 with the commutator segment 4. Of course, it goes without saying that the commutator segment 4 and the brush sliding part 3, which are in contact with each other, are subject to mechanical wear that is not caused by electrical sparks.

Generally, the material of the brush sliding part 3 that is often used is noble metal alloy or sintered carbon as mentioned above, and the material of the commutator segment 4 is Au, Pd, Ag.
Noble metal alloys such as AgCu, AgCd, AgC
uCd, AgCuTi, etc.). In particular, when used in combination with a noble metal brush, since both have high surface energy and are made of substantially the same material, this is an unfavorable combination that tends to cause abrasions on the contact surfaces. In addition, even when combined with a sintered carbon brush, although the sliding resistance is lower than that of a noble metal alloy brush, the blended materials that make up the brush contain a considerable amount of impurities such as SiO□. There is a risk of abrasions, and as with noble metal alloy brushes, noble metal alloy carbon is an unfavorable combination that tends to cause abrasions on the mating surfaces. The example of FIG. 5(a) shows a structure without mechanical means to suppress the electrical sparks that cause these defects. That is, if no vibration damping measures are taken for the brush sliding part 3, the vibration of the brush sliding part will be large, sparks will be generated more often, and welding and wear will easily occur.

The example in FIG. 5(b) shows a configuration in which vibration damping measures are taken for the brush sliding section 3. That is, vibration isolating rubber 9 is attached to brush sliding part 3 with adhesive 8, and vibration absorption is good at room temperature, and generation of sparks can be suppressed. However, near the upper limit temperature of 60°C, the viscosity of the adhesive decreases significantly, and the adhesive force between the anti-vibration rubber 9 and the sliding part 3 decreases, resulting in a decrease in vibration absorption ability and increased occurrence of sparks. , it becomes difficult to obtain high-quality products with long lifespans. Furthermore, FIG. 5(c) shows another example of a structure in which vibration damping measures are taken for the brush sliding portion 3, similar to FIG. 5(b). That is, the vibration-proof sheet 12 is attached to the base material 1 on the brush sliding part 3.
0 with an adhesive 11 having a structure in which an adhesive 8 is applied to both sides of the adhesive 8, and compared to the example shown in FIG. However, it is insufficient and cannot satisfy long life and high quality at high temperatures.

The ambient temperature for this device is -10°C to +60°C.
Many are used at ℃.

The present invention aims to prevent wear and tear of the brush and commutator caused by sliding between the motor brush and the commutator, abrasion damage due to welding, and shortening of motor life due to mechanical wear.

Means for Solving the Problems In order to solve the above problems, a brush base made of a thin plate-shaped or linear metal elastic body, and a brush base extending from the brush base or fixed to a part of the brush base are provided. In a small motor equipped with a brush having a brush sliding part, a member impregnated with 7-menthanol, such as felt, is fixed with adhesive or attached to a part of the motor case, for example, near the brush sliding part on the bracket. Attach by crimp method or other means.

This 7-menthanol becomes vapor depending on the ambient temperature,
The inside of the motor case is configured to have an atmosphere of 7-menthanol. In order to simplify the motor configuration, a configuration may be used in which the 7-menthanol is directly applied to the brush or the brush sliding portion.

Effect: Previous literature and experiments have revealed the conditions in which the brush sliding part and the commutator segment tend to weld, or the conditions in which welding, abnormal wear, or poor continuity occur. The condition where abnormality is likely to occur is the atmosphere of the part where the brush sliding part and the commutator segment move.
Alternatively, unsaturated cyclic hydrocarbons may be present or adsorbed in the commutator segment itself. At this time, an abnormal phenomenon called blackness (a mixture of decomposition products or carbon-like polymers produced by mechanochemical reactions and sliding wear particles generated between the brush and the commutator segment) is promoted. Foreign matter is generated.

This foreign material is caused by the fact that when unsaturated cyclic hydrocarbons are combusted by the arc between the sliding part and the commutator segment, the amount of carbon per unit volume is large, resulting in incomplete combustion, and the molecular structure of the unsaturated cyclic hydrocarbons. However, this is thought to be because the bonding state of the produced carbon becomes dense, resulting in hard carbon.

In addition, it was found that when hydrocarbons other than unsaturated cyclic hydrocarbons are adsorbed in the atmosphere and on the commutator segment, the carbon produced is soft and does not lead to abnormal phenomena, although this is due to its molecular structure. has been done. Based on these phenomena, a long-term operation experiment was conducted using a commutator segment that adsorbed a small amount of hydrocarbons. In this experiment, we found that: 1) There is a high probability that abnormal wear will occur in the commutator segment under high temperature and low humidity.

2) If the commutator segment adsorbs about 10I1g of unsaturated cyclic hydrocarbons such as toluene, the abnormality of the commutator segment will be alleviated and the life of the small motor will be extended (however, unsaturated cyclic carbonization will continue). Results were obtained (the data are for the case without hydrogen replenishment).

Considering the above phenomenon, we found that when 7-menthanol is used, unlike styrene monomers and toluene, it burns well because it has oxygen in its molecular structure, resulting in the formation of hard black matter, which is the cause of the abnormal phenomenon. Even if carbon is generated, it is extremely soft and reduces the sliding resistance of the brush sliding part and commutator segment.

In addition, this effect is due to the fact that an atmosphere suitable for the vapor pressure of 7-menthanol can be created in the motor case even at high temperatures and low humidity where abnormal phenomena are likely to occur, and that the polar groups of 7-menthanol can be applied to metal surfaces. It has strong adsorption, so you can get the full effect.

In addition, the small motor that uses 7-menthanol has a nearly hermetic structure with little air circulation, but better results will be obtained if the equipment in which the small motor is installed itself has a structure with less air circulation. .

7 Au', Pd, and Pt by adsorption of menthanol.

Commutator segments and brushes made of highly catalytic materials such as Ag, etc. and their alloys, as well as C.
It also adsorbs to the surfaces of sintered carbon brushes, etc., and the surfaces of other metal parts that make up the motor, and prevents highly reactive gases (styrene monomer, toluene, etc.) from adhering to the surfaces. To prevent. This is because 7-menthanol is more strongly adsorbed than organic gases, such as styrene monomers and toluene, which are adsorbed by van der Waals attraction. The names and properties of drugs effective in the present invention are shown below.

Margin below.

Molecular formula: Cb H9 (CHz 0H) (i CjH7
) Molecular structure: Boiling point = 236°C (1 atm) Melting point: 20°C (1 atm) Water absorption heavy industry 0% (40°C, 9o% RH, 1 atm) The aforementioned 7-menthanol is adsorbed on the brush, commutator segment surface. However, since a monomolecular film is formed, the lubricity is greatly improved and wear of the contact parts is significantly reduced.

Embodiment FIGS. 1, 2 and 3 each show an embodiment of the present invention. Here, parts with the same names as those in FIG. 4 are given the same reference numerals. In the figure, 7 is a bearing metal, 13 is a brush, 14 is a bracket that holds the brush 13, etc., 15 is under the motor case, 16 is felt impregnated with 7 menthanol, 17 is a rotor core 18
Magnet wire wrapped around, 19 is motor case 2
It is a field magnet fixed to the inner surface of 0. 1st
In the embodiment shown, the felt 16 is placed near the brush sliding part 3 on the bracket 14, and in the embodiment shown in FIG. 2, the felt 16 is mounted on the brush base 2, and in the embodiment shown in FIG. In the example, the motor case 20 is installed away from the brush 13. In the embodiments shown in FIGS. 1 and 2, the brush sliding part 3 made of a carbon brush is fixed to the tip of the brush base 2. A brush sliding part may be provided, and the felt 16 may be placed on the sliding part.

In addition, in both examples, the atmosphere inside the motor case is 7.
The purpose is to create a vapor atmosphere of menthanol and adsorb 7-menthanol onto the brush and commutator segment surfaces, but the means for achieving this is not limited to this.

Figure 6 shows the results of the conventional product, Comparative Example 1) tested in a styrene monomer atmosphere, Comparative Example 2) tested in a toluene atmosphere, and the present invention tested in a 7-menthanol atmosphere. .

Note that even if there are some impurities in the components of 7-menthanol, 7-menthanol still exhibits a remarkable effect.

The results of the experiment shown in FIG. 6 in the example will be explained using the motor shown in FIG. 3. This motor is a DC motor with an outer diameter of 30mm.
The size is 25 mm in height, the rated output is 0.1 W, and the operating conditions during the test are 4.2 VDC and 125 mA.

When a polyester felt 16 that had been cleaned and degreased with a polyfluoroethylene solution and impregnated with 7-menthanol was installed in the gap of the motor, 7-menthanol gradually emitted and a remarkable effect could be obtained. The evaporation speed of the polyester felt 1-16 can be controlled by changing the fiber thickness and final specific gravity. Remarkable effects could also be obtained by using open-cell foamed plastic or rubber sponge instead of the polyester felt 16.

In addition, sintered porous field magne throat 1
9 impregnated with 7-menthanol had a holding power of 0.1 to 0.3 g, and a remarkable effect could be obtained. Also, in the same way, the plastic bracket 14
blended into the plastic commutator base 5, impregnated into the magnet wire 17, blended into the metal oil of the bearing metal 7, impregnated into the gap between the magnet 19 and the motor case 20. It was blended with anti-vibration rubber 9, blended with anti-vibration rubber pasting adhesive 8 shown in Fig. 5, and sealed in a gas-permeable film or case such as polyethylene and installed inside a small motor. It also has the ability to retain 7-menthanol and has a remarkable effect.

In addition, in Figure 6G, (a) shows the rectification waveform before the test of the conventional product in an atmosphere of 60°C and 5% RH, and the rectification waveform after the 300-hour test, and (b) shows the rectification waveform of the conventional product in an atmosphere of 60°C and 5% RH. Rectification waveform before the 60°C, 5% RH atmosphere test in a hydrocarbon styrene monomer atmosphere and Comparative Example 1 after 100 hours test
(c) shows a comparison of the rectification waveform before the 60°C, 5% RH atmosphere test and after the 300-hour test when approximately 10 μg of unsaturated cyclic hydrocarbon (toluene) is adsorbed on the surface of the commutator segment. The rectified waveform of Example 2 is shown, and (d) shows the rectified waveform before the test in a benzyl alcohol atmosphere at 60° C. in a 5% atmosphere and after the 1500-hour test, respectively.

Effects of the Invention As is clear from the above description, the present invention provides the following effects.

1) By adsorbing 7-menthanol to the surfaces of the brushes and commutator segments, a lubricating effect is exerted, which has the effect of preventing abnormal wear and welding of the contact surfaces and the resulting abrasion damage. Table 1 shows an example of the results.

2) Even if there is an organic gas with a benzene ring such as styrene monomer or toluene, it is protected by a film of 7-menthanol adsorbed on the brush and commutator segment surfaces.
The formation of black compounds is also reduced to a minimum, and it is possible to prevent poor contact between the brush and the commutator segment. In addition, since contact failure does not occur, the generation of electrical noise is also reduced, and the speed of small motors is stabilized.
To reduce wow and flutter in equipment in which a small motor for relatively low voltage such as V is used. Table 1 shows an example of the results.

3) Due to the lubricating effect of 7-menthanol, when a commonly used micromotor with an operating voltage of 1 to 30 V and a current value of around 100 mA is operated in an atmosphere of 7-menthanol, the current value decreases by 5-10%, resulting in energy savings. . Table 1 shows an example of the results.

4) 7-menthanol has a damping effect that suppresses vibrations generated by the sliding movement of the brush and commutator,
Allows for a 1-10% reduction in mechanical noise. In other words, it has almost the same noise-damping effect as the vibration-proof rubber normally attached to brushes. Table 1 shows an example of the results.

5) The hygroscopicity of 7-menthanol is hydrophilic - O
The balance between the H group and the hydrophobic 10-C- (carbon bond) is ideal, and the water absorption rate is less than 20% even in an atmosphere of 40°C and 90% RH, making it so wet that it corrodes metal. It has a great lubrication effect without any problems.

As a result of steps) to 5) above, the quality of the small motor was improved and its lifespan was significantly extended.

Margin below.

[Brief explanation of drawings]

1 and 2 are configuration diagrams of an embodiment of the present invention, FIG. 3 is a half-sectional view of a motor of an embodiment of the present invention, and FIG. 4 is a diagram showing the configuration of a general brush and a commutator. Fifth
Figures ('a) to (c) are diagrams showing typical configurations of brush sliding parts in conventional examples, respectively, and Figures 6 (a) to (d) are small-sized ones in conventional examples, comparative examples, and embodiments of the present invention. FIG. 3 is a diagram showing a rectified waveform of a motor. 3... Commutator sliding part, 4...
- Commutator segment, 14...Bracket, 16...Felt, 20...Motor case.

Claims (1)

[Claims] A small motor having a brush mechanism and a commutator, the brush and the commutator sliding, characterized in that an atmosphere of 7-menthanol is provided in the motor case.