JPS6231346A - Miniature motor - Google Patents

Abstract

PURPOSE:To prevent not only the abnormal abrasion and welding of the slide contact face but the fretting damage thereby by impregnating the atmosphere inside a motor case with the benzyl alcohol. CONSTITUTION:At a portion inside motor case 20, e.g., close to the brush slide on a bracket 14, the member impregnated with the benzyl alcohol, e.g., a felt 16, is contactingly provided by means of securing with an adhesive of fixing by pressure. By the atmospheric temperature this benzyl alcohol is vaporized so that the ambient atmosphere inside the motor 20 may be of the benzyl alcohol. Thus, the benzyl alcohol is absorbed into the surfaces of a brush 13 and commutator segment and 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 the use of elastic conductive materials such as copper, beryllium copper, copper titanium alloys, phosphor bronze, nickel silver thin sheets or wires, and precious metal alloys (such as Au, Pd, Pt,
The structure is made by cladding (Ag, Cu, etc. and their alloys) or by spot welding a part of the thin plate material or wire rod. Sintered carbon brush (e.g. carbon,
Ag carbon, Cu carbon, AgCu carbon, and SiC, M for those materials.

These brushes are formed using conductive adhesives, spot welding, or caulking methods.In small motors that include these brushes, commutator During rotation, the brush sliding part vibrates unnecessarily, resulting in abnormal welding on the contact surface of the brush sliding part with the commutator segment, and blackening (carbon and carbon) caused by spark generation. The problem is that foreign matter that promotes abnormal phenomena (mixed with sliding abrasion powder generated between parts) is often generated. 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 Sin. 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 shown 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-like 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 benzyl alcohol, such as felt, is fixed with adhesive to a part of the motor case, for example, near the brush sliding part on the bracket. Alternatively, it may be attached using a crimp method or other means.

This benzyl alcohol turns into vapor depending on the ambient temperature, and the inside of the motor case is configured to have a benzyl alcohol atmosphere. In order to simplify the motor configuration, a configuration may be used in which the Hensyl alcohol 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 abnormalities are likely to occur is that the atmosphere of the area where the brush sliding part and the commutator segment slide is
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 10 μg 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 to occur). Results were obtained (the data are for the case without hydrogen replenishment).

Considering the above phenomenon, we found that when benzyl alcohol is used, unlike styrene monomer or toluene, it burns well because it has oxygen in its molecular structure, resulting in the formation of hard black particles, 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 benzyl alcohol can be created in the motor case even at high temperatures and low humidity where abnormal phenomena occur. It has strong adsorption, so you can get the full effect.

In addition, better results will be obtained if the small motor containing benzyl alcohol has a nearly hermetic structure with little air circulation, or if the device itself in which the small motor is installed has a structure with little air circulation. .

By adsorption of benzyl alcohol, Au, Pd, Pt, Ag
, etc. and their alloys, as well as commutator segments and brushes made of materials with strong catalytic action, those made of Cu, etc., the surfaces of sintered carbon brushes, and the surfaces of other metal parts constituting the motor. It also absorbs into
Prevents highly reactive gases (styrene monomer, toluene, etc.) from adhering to the surface. This is because benzyl alcohol adsorbs more strongly than organic gases, which are adsorbed by van der Waals attraction such as styrene monomers and toluene. The names and properties of drugs effective in the present invention are shown below.

Margin below.

Molecular formula: Cb H5・CH20H Molecular structure: CH2-OH Boiling point: 205°C (1 atm) Melting point: 15°C (1 atm) Water absorption: 2% (40°C, 90% RH - 1 atm) The above-mentioned benzyl Alcohol adsorbs to the surfaces of the brushes and commutator segments and forms a monomolecular film, which greatly improves lubricity and significantly reduces wear on the contact parts.

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 benzyl alcohol, 17 is a magnet wire wrapped around the rotor core 18, 19 is a field magnet fixed to the inner surface of the motor case 20.

In the embodiment shown in FIG. 1, the felt 16 is placed near the brush sliding part 3 on the bracket 14, and
In the illustrated embodiment, a felt 16 is attached to the brush base 2. 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 mounted on the sliding part.

In addition, in each of the embodiments, the atmosphere inside the motor case becomes a vapor atmosphere due to benzyl alcohol, and the purpose is to cause benzyl alcohol to be adsorbed on the brush and commutator segment surfaces, but the means for achieving this are 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 benzyl alcohol atmosphere. .

Note that even if there are some impurities in the components of benzyl alcohol, benzyl alcohol still exhibits remarkable effects.

The results of the experiment shown in FIG. 6 in the example will be explained using the motor shown in FIG. This motor is a DC motor with an outer diameter of 30m.
The size is 25 mm in height, the rated output is 0, IW, and the operating conditions during the test are 4.2 VDC and 25 mA.

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

In addition, a sintered porous field magnet 19
The material impregnated with benzyl alcohol had a holding power of 0.1 to 0.3 g, and a remarkable effect could be obtained. Also, in the same way, plastic bracket 1
4, plastic commutator base 5
blended with oil, 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, blended into the anti-vibration rubber 9, Blends with the adhesive 8 for attaching anti-vibration rubber shown in Figure 5, and those sealed in a gas-permeable film or case such as polyethylene and installed inside a small motor also have the ability to retain benzyl alcohol and have a remarkable effect. I was able to get it.

In Fig. 6, (a) shows the rectification waveform of the conventional product before the test and after the 300-hour test in an atmosphere of 60°C and 5% RH, and (b) shows the rectification waveform of the unsaturated cyclic hydrocarbon styrene. The rectification waveform before the 60°C, 5% RH atmosphere test in a monomer atmosphere and the rectification waveform of Comparative Example 1 after the 100-hour test are shown. The rectified waveform before the 60°C, 5% RH atmosphere test and the rectified waveform of Comparative Example 2 after the 300-hour test are shown when about 10 μg is adsorbed, and (d) shows the rectified waveform of Comparative Example 2 at 60°C and 5% RH in the benzyl alcohol atmosphere of the present invention. The rectified waveform before the % atmosphere test and the rectified waveform after the 1500 hour test are shown, respectively.

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

1) Benzyl alcohol adsorbs to the surfaces of the brushes and commutator segments, providing a lubricating effect and 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 will be protected by a film of benzyl alcohol adsorbed to the surfaces of the brushes and commutator segments, and the formation of black matter will be minimal, and the gas between the brushes and commutator segments will be protected. It is possible to prevent the occurrence of poor contact. In addition, since there is no contact failure, electrical noise generation is also reduced.
The speed of the small motor was also stabilized, and as a result, the speed of 1~
To reduce wow and flutter in equipment in which a small motor for relatively low voltage of about 30V is used. Table 1 shows an example of the results.

3) Due to the lubricating effect of benzyl alcohol, 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 benzyl alcohol, the current value decreases by 5 to 10%, resulting in energy savings. . Table 1 shows an example of the results.

4) Benzyl alcohol has a damping effect that suppresses vibrations generated by the sliding motion of the brush and commutator, making it possible to reduce mechanical noise by 1 to 10%. 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 benzyl alcohol has an ideal balance between the hydrophilic 10H group and the hydrophobic 1C-C- (carbon bond), even in an atmosphere of 40℃ and 90%RH. The water absorption rate is 20% or less, and the lubricating effect is large without being so wet that it corrodes the metal.

As a result of 1) to 5) above, the quality of the small motor was improved and its lifespan was significantly extended.

Margin below.

[Brief explanation of the drawing]

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 examples of the present invention. FIG. 3 is a diagram showing a rectified waveform of a motor. 3... Commutator sliding part, 4...
- Commutator segment, 14... Placket, 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 a benzyl alcohol atmosphere is provided in the motor case.