JPH0568933B2 - - Google Patents

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 Structure and Problems There are generally two types of brushes used in small motors. One is to add noble metal alloys (such as Au, Pd, PT, Ag, Cu, etc.) to elastic conductive materials, such as copper, beryllium copper, copper-titanium alloys, phosphor bronze, and nickel silver thin sheets or wires. The other is a structure in which a part of the thin plate material or wire rod is joined by means such as spot welding, and a part of the thin plate material or wire rod is clad with sintered carbon. Brush (e.g. C
Carbon, Ag carbon, Cl carbon, AgCu carbon, and carbon brushes made from these materials with SiC, MoS ₂ , Pb, epoxy resin, etc. as additives) can be used with conductive adhesives, spot welding, crimping, etc. However, in small motors having these brushes, the commutator sliding part unnecessarily vibrates when the commutator rotates, and this causes the contact surface of the commutator sliding part with the commutator segment to deteriorate. This is said to be caused by abnormal welding and blackening (a mixture of carbon and sliding abrasion powder generated between the brush and the commutator segment) caused by the generation of sparks. The formation of foreign substances that promote abnormal phenomena often occurs and becomes a problem.

In some brushes for small motors, a commutator sliding portion that slides on a commutator segment is molded integrally with a brush base that is supported by support means provided on, for example, a lid of a motor case. The contact between such a brush and the commutator segment is shown in FIG.

In FIG. 1, a bent commutator sliding portion 3 extends from a brush base 2 supported by a brush support means 1. This commutator sliding portion 3 has elasticity due to being bent from the brush base 2, and is in contact with the commutator segment 4 in a pressed state. and,
This pressing force can be achieved by appropriately selecting the bending angle between the brush base 2 and the commutator sliding part 3.
It can be any value you want. Further, the commutator segment 4 is fixed to the motor rotating shaft 6 via an insulating cylinder 5, and rotates with the rotation of the motor.

Since the rotating commutator segment 4 and the commutator sliding part 3 are in sliding contact, electrical sparks are likely to occur between them, and the generation of these electrical sparks can cause electrical noise and the commutator sliding part 3. Unfavorable conditions such as welding on the portion 3 will occur. The occurrence of this welding not only shortens the life of the brush, but also when welding occurs at the position where it starts to come into contact with each commutator segment 4 and at the position where it leaves (section a in Fig. 1),
This welding scrapes and damages the surface of the commutator segments 4, and furthermore, the cutting layer produced by this scraping collects in the gap between adjacent commutator segments 4, thereby causing the commutator segments 4 to become damaged. There is a disadvantage that the segments are electrically connected to each other, and the performance of the motor itself is degraded. Incidentally, electric sparks are often generated at section a of the commutator sliding section.

The biggest cause of this is the vibration of the brush. That is,
Vibration of the brush frequently generates electric sparks, which promotes welding and causes roughening of the sliding surface. As the roughness increases, the number of electric sparks increases, and eventually it becomes impossible to obtain the required characteristics of the motor, leading to the motor stopping.

Generally, the material of the commutator sliding part 3 is a noble metal alloy brush or a sintered carbon brush as mentioned above, and the material of the commutator segment 4 is AgCu, AgCd, AgCuCd, Cu, Au alloy,
AdPd alloy, AgCuTi alloy, etc. When using a noble metal alloy brush, the sliding resistance is as high as 1.0 because the two materials are almost the same, which is an unfavorable combination that tends to cause scratches at the sliding interface. It is. Furthermore, although the sliding resistance is lower when using a sintered carbon brush than when using a noble metal alloy brush, there is a risk of scratches, and the compounded materials that make up the carbon brush contain SiO ₂ These impurities are mixed in, creating an unfavorable combination in which abrasions are likely to occur at the sliding interface, similar to noble metal alloy brushes.

If the structure shown in Figure 2a does not have a means to suppress the electric sparks that cause these defects, that is, if no vibration damping measures are taken in the commutator sliding part 3, the commutator The vibration of the sliding parts is large, and therefore welding easily occurs even when used at room temperature, making it difficult to obtain a product with a long life and excellent quality. In addition, as shown in FIG.
It has good vibration absorption at room temperature and can suppress the generation of sparks, but when the temperature reaches the upper limit of 60℃, the viscosity of the adhesive decreases significantly, and the vibration isolating rubber 7 is attached to the sliding part. The adhesive strength of the material decreases, the vibration absorption ability decreases, and sparks occur more frequently, resulting in a product with a short life and unstable quality.
Furthermore, as shown in FIG. 2c, the anti-vibration sheet 9 is attached to the commutator sliding part 3 with an adhesive 11 having adhesive 8 applied to both sides of the base material 10, as shown in the second Compared to the example shown in FIG. b, the decrease in the viscosity of the adhesive at high temperatures is somewhat small, but it is not sufficient, making it impossible to achieve long life and high quality at high temperatures.

Please note that the ambient temperature for this device is -10℃~
Many are used at +60℃.

Purpose of the Invention The present invention aims to improve the sliding properties of the commutator sliding part and the commutator segment, prevent shortening of the motor life due to scratch damage on the commutator segment surface, and further improve the sliding properties of the commutator segment. The present invention provides a high-performance small motor that reduces wow and flutter when incorporated.

Structure of the Invention In order to achieve the above object, the present invention provides a brush base made of a thin plate or linear metal elastic body, and a brush base extending from the brush base or fixed to a part of the brush base. In a small motor equipped with a brush having a commutator sliding part,
A member impregnated with ester alcohol, such as felt, is installed in a part of the motor case, for example, near the commutator sliding part on the bracket, by fixing it with an adhesive or using a pressure bonding method. This ester alcohol has a linear carbon bond without a benzene ring, or has a side chain, and has one or more -OH groups in its molecular structure. It is particularly effective to select a material with a boiling point of around 250°C from those with a boiling point around 100°C depending on the usage situation. This ester alcohol turns into vapor depending on the ambient temperature, and the inside of the motor case is configured to be in an atmosphere of ester alcohol.

In order to simplify the motor configuration, a configuration may be used in which the ester alcohol is directly applied to the brush or the commutator sliding portion.

DESCRIPTION OF EMBODIMENTS FIG. 3, FIG. 4, and FIG. 5 each show an embodiment of the present invention. Here, parts with the same names as those in Figure 1 are given the same symbols, and 1
2 is a bracket for holding brushes, etc., 13 is a motor housing, and 14 is felt impregnated with ester alcohol. Note that the commutator sliding portion 3 is composed of a carbon brush.

In the embodiment of FIG. 3, the felt 14 is located on the bracket 12 near the commutator slide 3, and in the embodiment of FIG. 4, the felt 14 is mounted on the brush base 2.

Further, in the embodiment shown in FIG. 5, the motor housing 13 is equipped with a felt 14. In FIG. 5, 15 is a rotor core attached to the motor rotating shaft 6, 16 is a winding wound around the rotor core 15, 17 is a permanent magnet fixed to the inner surface of the motor housing 13, and 18 is a permanent magnet fixed to the inner surface of the motor housing 13. This is a bearing that supports the motor rotating shaft 6.

In addition, in all of these embodiments, the commutator sliding part 3 is fixed to the tip of the brush base 2, but as shown in FIG.
It has a commutator sliding part bent and extended from the
A felt 14 may be provided on the sliding portion. In either embodiment, the atmosphere inside the motor case consisting of the motor casing 13 and the bracket 12 becomes a vapor atmosphere due to ester alcohol, and the atmosphere gas is intended to adsorb onto the surfaces of the brushes and commutator segments. Yes, but this is not the only way to do it.

By the way, in the literature and experiments to date, the conditions in which the commutator sliding portion and the commutator segment are likely to be welded together, or the conditions in which welding, abnormal wear, or poor conduction are likely to occur are being clarified. Conditions where abnormalities are likely to occur include the brush sliding part and the commutator.
This is the case when unsaturated cyclic hydrocarbons are present or adsorbed in the atmosphere of the sliding portion of the segment or in the commutator segment itself. At this time, a foreign substance called blackide (a mixture of carbon and sliding abrasion powder generated between the brush and the commutator segment) is generated which promotes the abnormal phenomenon.

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

In addition, when hydrocarbons other than unsaturated cyclic hydrocarbons are adsorbed in the atmosphere and on the commutator segment, the carbon produced is soft, although this is due to its molecular structure, and it is unlikely that this will lead to abnormal phenomena. It has been clarified. Based on these phenomena, we conducted long-term operation experiments using a commutator segment that adsorbed trace amounts of hydrocarbons. In this experiment, there is a high probability that abnormal wear will occur in the commutator segment under high temperature and low humidity.

If about 10 μg of hydrocarbons are adsorbed in the commutator segment, abnormal phenomena in the commutator segment will be alleviated and the life of the small motor will be extended. (However, this data is based on the case where there is no continuous replenishment of hydrocarbons.) (The results of the experiment are shown in Figure 6).

Therefore, in consideration of the above phenomenon, the present invention provides a third
As shown in the embodiments shown in FIGS. 4 and 5, a felt 14 impregnated with ethyl alcohol is placed inside the motor housing 13 and the bracket 12. These ester alcohols are the most different from unsaturated cyclic hydrocarbons in terms of their molecular structure, and therefore are the ones that are the most distant from the formation of hard black compounds, which is one of the abnormal phenomena, and even if carbon formation occurs, It is extremely soft and reduces the sliding resistance between the commutator sliding part and the commutator segment.

In the above configuration, at high temperatures and low humidity where abnormal phenomena are likely to occur, an atmosphere corresponding to the vapor pressure of ester alcohols is obtained in the motor case. Ester alcohols that do not have double bonds or benzene rings, have linear carbon bonds, or have side chains have one or more -OH groups in their molecular structure. ,−
Owing to its polarity, the OH group has adsorption power to the metal surface through hydrogen bonding.

Adsorption due to hydrogen bonds is adsorbed with more than twice the force of the adsorbed organic gas due to the Van der Waals attraction, and can be said to be a stable adsorption state. By adsorption of this ester alcohol, Pt,
Commutator segments and brushes made of Au, Pd, Ag, etc., which have strong catalytic effects, are adsorbed not only to those made of Cu, but also to the surfaces of sintered carbon brushes and other metal surfaces. Prevents highly reactive gases (styrene monomer, toluene, etc.) from adhering to the surface.

This is because the adsorption power of the -OH group results in hydrogen engagement adsorption that is stronger than, for example, Van der Waals adsorption of styrene monomer or toluene. In addition, even if combustion occurs in the arc between brushes, commutators, and segments, ester alcohols have oxygen in their molecular structure, so there is little generation of tar due to incomplete combustion, resulting in poor contact. There is very little blackide produced, it burns well, and does not cause contact failure.

Moreover, for small motors whose normal operating environment range is -10℃ to +60℃, the boiling point at 1 atmosphere is 100℃.
Of the substances around 250°C, those around 250°C are particularly effective. Listed by type of ester alcohol, ethyl lactate...154°C (boiling point at 1 atmosphere) Ethyl glycolate...160°C (at 1 atmosphere) boiling point) 2-hydroxyethyl acetate...188℃
(Boiling point under 1 atm) Diethyl L-malate...253°C (boiling point under 1 atm) etc. Among these, ethyl lactate, ethyl glycolate, etc., which have low boiling points, are more effective if they are adsorbed onto the surface of the brush or commutator immediately after manufacturing the brush or commutator, or before assembling the motor. .

The above-mentioned ester alcohols adsorb to the surfaces of the brush and commutator and form a monomolecular film, so the lubricity is greatly improved and the wear of the contact parts is significantly reduced. (The results of the experiment are shown in Figure 6.) In Figure 6, A and B show the rectified waveforms in a styrene monomer atmosphere containing unsaturated cyclic hydrocarbons, and A shows the rectified waveforms before the 60°C, 5% RH test. B is the rectified waveform after a 100-hour test at 60°C and 5% RH. In addition, for C and D, approximately 10 μg of hydrocarbon (toluene) is applied to the surface of the commutator segment.
Showing the confirmation results when adsorbed, C is 60℃, 5
Rectified waveform before %RH test, D is 60℃, 5%
This is the rectified waveform after a RH300 hour test. Furthermore, E and F show the confirmation results in an ester alcohol atmosphere according to the present invention, where E is the rectified waveform before the 60°C, 5% RH test, and F is the rectified waveform after the 60°C, 5% RH test for 1500 hours. .

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

By adsorbing the ester alcohol to the commutator segment and the brush surface, a lubricating effect works, which has the effect of preventing abnormal wear and scratch damage on the sliding parts.

Even if there is an organic gas with a benzene ring such as styrene monomer or toluene, it will be protected by the ester alcohol film adsorbed on the brush and commutator segment surfaces, and the formation of black matter will be minimal, resulting in contact between the brush and commutator segment. Defects can be prevented. In addition, since contact failures do not occur, the generation of electrical noise is reduced, and the speed of small motors that would otherwise occur due to unstable contact is stabilized, resulting in less wow and flutter in equipment that uses small motors. It has the effect of reducing

As a result of the above, the quality of small motors for relatively low voltages of about 1V to 30V can be improved, and the lifespan can be significantly extended.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional example, FIGS. 2 a to c are diagrams showing the configuration of a commutator sliding part of a conventional example, and FIGS. 3 and 4 are configuration diagrams of an embodiment of the present invention, respectively. FIGS. 5a and 5b are vertical and horizontal sectional views of a small motor according to still another embodiment of the present invention, and FIGS. 6A to 6F are diagrams showing rectified waveforms of the conventional example and the present invention. 3...Commutator sliding part, 4...Commutator segment, 12...Bracket, 13...
Housing, 14...Felt impregnated with ester alcohol.

Claims (1)

[Claims] 1. A small motor that has a brush mechanism and a commutator, and has a structure in which the brush and the commutator slide in contact with each other, has a linear carbon bond in the motor case, or has a side chain, and has a single or a single carbon bond in its molecular structure. A small motor with an atmosphere of ester alcohols with multiple -OH groups.