JPH0568935B2 - - 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 Structures and Problems There are generally two types of brushes used in small motors.

One is to use elastic conductive materials such as copper, beryllium copper, copper-titanium alloys, phosphor bronze, nickel silver thin sheets or wires, and noble metal alloys (such as Au,
This is a structure in which Pd, Pt, Ag, Cu, etc. and their alloys are clad or joined to a part of a thin plate material or wire rod by means such as spot welding, and the other is the thin plate material mentioned above. , or a sintered carbon brush as a part of the wire (e.g., C carbon, Ag carbon, Cu carbon, AgCu carbon, and carbon brushes made of these materials mixed with SiC, MoS ₂ , Pb, epoxy resin, etc.) ) are formed by means such as conductive adhesive, spot welding, or crimping, but in small motors with these brushes, the commutator sliding part vibrates unnecessarily when the commutator rotates. This allows the commutator sliding part of the commutator to
This promotes the occurrence of abnormal welding on the contact surface with the segment and the abnormal phenomenon called blackening (a mixture of carbon and sliding wear particles generated between the brush and the commutator segment) due to the generation of sparks. Foreign matter is often generated 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 causes abrasion and damage to the surface of the commutator segments 4, and furthermore, cutting debris generated by this abrasion 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,
AgPd alloy, AgCuTi alloy, etc., and 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.
The adhesive that is pasted has good vibration absorption at room temperature and can suppress the generation of sparks, but when the temperature reaches the upper limit of 60°C, the viscosity of the adhesive decreases significantly, causing damage to the sliding parts of the vibration isolating rubber 7. 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 to some extent 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 compact 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 ketone, such as felt, is fixed with adhesive or crimped to a part of the motor case, for example, near the commutator sliding part on the bracket. installation method or other means. This ketone does not have a benzene ring, has a linear carbon bond, or has a side chain, and has one or more -CO- polar groups in its molecular structure,
From a substance whose boiling point is around 100℃ under 1 atmosphere
One suitable for use depending on the usage situation is particularly effective at around 250°C. The structure is such that this ketone turns into vapor depending on the ambient temperature and the inside of the motor case is under a ketone atmosphere. Note that in order to simplify the motor configuration, a configuration may be used in which the ketone 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 12
13 is a motor housing, and 14 is a felt impregnated with ketone. Note that the commutator sliding portion 13 is composed of a carbon brush. In the embodiment of FIG.
The felt 14 is located on the bracket 12 in the vicinity of 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 housing 13 and the bracket 12 is made into a vapor atmosphere due to ketones, and the atmospheric gas is intended to adsorb onto the surfaces of the brushes and commutator segments. However, the method is not limited to this.

By the way, in the literature and experiments to date, the conditions in which the commutator sliding portion and the commutator segment tend to weld easily, or the conditions in which welds, abnormal wear, or poor conduction easily 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 where the segment slides 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 abnormal phenomena.

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. Furthermore, it has been clarified that in atmospheres other than unsaturated cyclic hydrocarbons and when adsorbed to the commutator segment, the carbon produced is soft and does not lead to abnormal phenomena, although this is due to its molecular structure. There is. Based on these phenomena, we conducted long-term operation experiments using a commutator segment that adsorbed trace amounts of hydrocarbons.
In this experiment, there was a high probability of abnormal wear occurring in the commutator segment under high temperature and low humidity.

If about 10 μg of hydrocarbons are adsorbed on 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 the present invention, in consideration of the above phenomenon, the third
As shown in the embodiments shown in FIGS. 4 and 5, a felt 14 impregnated with ketones is placed inside the motor housing 13 and the bracket 12. These ketones differ most from unsaturated cyclic hydrocarbons in their molecular structure,
Therefore, it is farthest away from the formation of hard black particles, which is one of the abnormal phenomena, and even if carbon is formed, it is extremely soft, reducing the sliding resistance between the commutator sliding part and the commutator segment. .

In the above configuration, an atmosphere corresponding to the vapor pressure of ketones is obtained in the motor case at high temperatures and low humidity where abnormal phenomena are likely to occur. Ketones that do not have a benzene ring and have a linear carbon bond or a side chain have one or more -CO- polar groups in their molecular structure, and -
CO- groups strongly adsorb to metal surfaces due to their polarity.

Adsorption by the -CO- group is more strongly adsorbed than the adsorbed organic gas due to the Van der Waals attraction, and can be said to be a stable adsorption state. By adsorbing these ketones, the commutator segments and brushes with strong catalytic action made of Pt, Au, Pd, Ag, etc., as well as those made of Cu, the surface of the sintered carbon brush, and other It also adsorbs to metal surfaces, preventing highly reactive gases (styrene monomer, toluene, etc.) from adhering to the surface.

This is because the adsorption power of the -CO- group is stronger than, for example, the van der Waals adsorption of styrene monomer or toluene. In addition, even if combustion occurs in the arc between the brush and commutator segment, ketones have oxygen in their molecular structure, so there is little generation of tar due to incomplete combustion, and there is no possibility of poor contact. The formation of melanized substances is subtle, and it burns well and does not cause contact failure. Moreover, for small motors whose normal operating environment range is -10°C to +60°C, the boiling point at 1 atmosphere is
Of the substances around 100°C, those around 250°C are particularly effective, and when listed by type of ketone, 2-octanone...174°C (boiling point under 1 atmosphere) 2-nonanone...195°C (boiling point under 1 atmosphere) ) Diethyl succinate...218℃ (boiling point under 1 atmosphere) 2-undecanone...229℃ (boiling point under 1 atmosphere), etc.

The above-mentioned ketones adsorb to the surfaces of the brush and commutator and form a monomolecular film, so lubricity is greatly improved and 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. moreover,
E and F show the confirmation results in a ketone atmosphere according to the present invention, E is the rectified waveform before the 60° C., 5% RH test, and F is the rectified waveform after the 60° C., 5% RH 1500 test.

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

Adsorption of ketones to the commutator segment and brush surface provides a lubricating effect, which has the effect of preventing abnormal wear and abrasion damage on sliding parts.

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 ketones adsorbed on the brush and commutator segment surfaces, and the formation of black compounds will be subtle, resulting in contact between the brush, commutator, and segment. Defects can be prevented. In addition, since contact failure does not occur, the generation of electrical noise is reduced, and the speed of small motors that is caused by unstable contact is stabilized, resulting in wow and noise in equipment that uses small motors.
This has the effect of reducing flutter.

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 ketones.

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, and has a linear carbon bond in the motor case or a side chain, and has one or more carbon bonds in its molecular structure. A small motor with an atmosphere of ketones containing -CO- polar groups.