JPS59213260A - Small-sized motor - Google Patents

Abstract

PURPOSE:To prevent the life of a motor from shortening due to a frictional damage of the surface of a commutator segment by attaching a member impregnated with a fluid paraffin in the vicinity of an inner commutator slide surrounded by a housing and a bracket. CONSTITUTION:A felt 16 which is impregnated with fluid paraffin is disposed or mounted in the vicinity of an inner commutator slide surrounded by a motor housing 15 and a bracket 14 for holding a brush or on a brush base 2. The paraffin is different in a molecular structure from unsaturated cyclic hydrocarbon. Accordingly, it produces brown powder existing farthest from black powder or produces soft carbon except it, thereby reducing the slide resistance of the commutator slide with the commutator segment. Consequently, the abnormal wear of the slide and the frictional damage of the surface of the segment can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a small motor used for feeding a tape in, for example, a tape recorder, a videotape recorder, or the like.

(Structure and problems of conventional examples) In general, brushes in small motors are made of an elastic conductive material, such as a thin plate of copper-beryllium alloy. In a small motor in which a sheet material is attached to the longitudinal direction of the moving part, the commutator sliding part vibrates unnecessarily when the commutator rotates, which causes abnormalities on the contact surface of the commutator sliding part with the commutator segment. Welding may occur.

In some brushes for small motors, a commutator sliding portion that makes sliding contact with 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 a 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 part 3 is connected to the brush base 2
It has elasticity due to being bent from above, and is in contact with the commutator segment 4 in a pressed state. 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 with each other, 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
If welding occurs at the position where it starts and leaves contact with each commutator segment 4 (section a in Figure 1), this welding will scrape and damage the surface of the commutator segment 4, and the surface of the commutator segment 4 will be damaged. Cutting debris accumulates in the gap between adjacent commutator segments 4, which causes the inconvenience of electrical conduction between the commutator segments, which has the disadvantage that the performance of the motor itself deteriorates. . 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, electric sparks frequently occur due to the vibration of the brush, which promotes the occurrence of welding and causes roughness of the sliding surface. As the roughness increases, the generation of electric sparks further increases, and eventually it becomes impossible to obtain the required characteristics of the motor, leading to the motor starting and stopping.

Generally, the material of the commutator sliding part 3 is phosphor bronze, and the material of the commutator segment 4 is silver copper, silver cadmium,
These materials are copper, gold, etc., and since both are substantially the same materials, the sliding resistance is as high as 1.0, which is an unfavorable combination that tends to cause scratches at the sliding interface.

As a means for suppressing electric sparks that cause these defects and as a means for reducing sliding resistance, there is a method of applying grease 13 to the surface of the commutator segment 4.

However, with this method of applying grease 13, if the viscosity of the grease is too high, the contact pressure on the commutator sliding part will be insufficient, resulting in poor continuity, and if the viscosity is optimal at room temperature, the viscosity at low temperature will be insufficient. In some cases, the grease may rise and cause poor contact pressure, and when used at high temperatures, the viscosity of the grease decreases, causing it to scatter due to the rotational force of the commutator segment.

The ambient temperature for this device is -10°C to +60°C.
Many are used within the temperature range of ℃.

In the type that does not apply grease, as shown in Fig. 2(a), if no vibration damping measures are taken for the commutator sliding part 3, the vibration of the commutator sliding part is large; Therefore, even when used at room temperature, welding easily occurs, making it difficult to obtain a product with a long life and excellent quality. Also, as shown in FIG. 2(b), the commutator sliding part 3
The anti-vibration rubber 9 pasted with the adhesive 8 has good vibration absorption at room temperature and can suppress the generation of sparks, but the viscosity of the adhesive decreases significantly when the temperature reaches the upper limit of 60°C. However, the adhesion force of the anti-vibration rubber 9 to the sliding portion is reduced, the vibration absorption ability is reduced, and sparks are generated more frequently, resulting in a product with a short life and unstable quality. Furthermore, as shown in FIG. 2(c), the anti-vibration sheet 12 is attached to the commutator sliding part 3 using an adhesive 11 having a structure in which adhesive 8 is applied to both sides of the base material 10, as shown in FIG. Second
Compared to the example shown in Figure (b), the decrease in the viscosity of the adhesive at high temperatures is somewhat small, but it is not sufficient, and it is not possible to obtain a long life and high quality at high temperatures.

(Object 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 abrasion damage on the surface of the commutator segment, and also prevents shortening of the motor life due to scratch damage on the surface of the commutator segment. The present invention provides a high-performance compact motor that can reduce wow when

(Structure of the Invention) In order to achieve the above object, a brush is provided which has a brush base made of a thin metal elastic body and a commutator sliding part extending from the brush base or fixed to the tip of the brush base. In this small motor, a member impregnated with liquid paraffin, such as felt, is installed on the bracket inside the motor housing near the commutator sliding part. This liquid paraffin has a vapor pressure of 101~
Select an appropriate one depending on the usage situation, such as 10-1 mmHg.

The paraffin vapor that evaporates from the felt is adsorbed on the surface of the commutator segment and acts as a lubricant. In addition, even if this paraffin becomes carbide due to sparks between the commutator sliding piece and the commutator segment, it can act as a lubricant on the sliding surface, so it reduces the friction coefficient of the sliding part by about 1.0 and Prevents welding of moving parts.

(Description of Examples) FIG. 3 and FIG. 4 each show an example of the present invention. Here, parts with the same names as those in FIG. 1 are given the same reference numerals, and 14 is a bracket for holding brushes, etc., 15 is a motor housing, and 16 is felt impregnated with liquid paraffin. In the embodiment shown in FIG. 3, the felt 16 is placed near the commutator sliding portion 3 on the bracket 14, and in the embodiment shown in FIG. 4, the felt 16 is mounted on the brush base 2.

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 may have a moving part and the felt 16 may be placed on the sliding part.

By the way, previous literature and experiments have shown that the commutator sliding part and the commutator segment are easily welded,
In addition, the conditions in which welding, abnormal wear, and poor conduction are less likely to occur are being clarified.

Abnormalities are likely to occur when unsaturated cyclic hydrocarbons are present or adsorbed in the atmosphere of the area where the sliding part and the segment slide, or in the segment itself.

At this time, a foreign substance called black powder is generated that promotes abnormal phenomena.

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

In addition, when hydrocarbons other than unsaturated cyclic hydrocarbons are adsorbed in the atmosphere and on the segments, black powder is not produced, but a foreign substance called brown powder that does not cause abnormal phenomena is produced.

Brown powder has a smaller amount of carbon per unit volume than unsaturated cyclic hydrocarbons, and incomplete combustion is less likely to occur. Furthermore, it has been clarified that the generated carbon is also soft, which is due to its molecular structure, and does not lead to abnormal phenomena.

Based on these phenomena, we conducted long-term operation experiments using a commutator segment that adsorbed a small amount of hydrocarbons. In this experiment, 1) there is a high probability that abnormal wear will occur in the commutator segment under high temperature and low humidity.

2) 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.

The results were obtained.

Therefore, in the present invention, taking the above phenomenon into consideration, we have developed the
As shown in the illustrated embodiment, a felt 16 impregnated with liquid paraffin is placed near the commutator sliding part inside the motor housing 15 and the bracket 14. This liquid paraffin differs most from unsaturated cyclic hydrocarbons in its molecular structure, and therefore produces brown powder, which is the fastest present in black powder, or otherwise produces soft carbon, which makes it difficult for commutator sliding. This reduces the sliding resistance between the commutator segment and the commutator segment.

In the above configuration, at high temperatures and low humidity where abnormal phenomena are likely to occur, the vapor pressure of paraffin increases and the molecular weight becomes 11.
4 gr. 469 μg/cc at 60°C for n-octane
, molecular weight 142gr. n-decane has a molecular weight of 92 μg/cc at 60°C and a molecular weight of 170 gr. n of
- Dodecane exhibits a vapor pressure of 26 μg/cc at 60° C., and the vapor is adsorbed on the commutator segment 4 or carbonized by a sliding arc, which acts as a lubricant. The active metal surface created by the friction of sliding parts has the property of adsorbing everything, so
Easily adsorbs and retains paraffin vapors.

The liquid paraffin used in the present invention has a vapor pressure of 1
01mmHg order (n-octane), 10°
An order type (n-decane) and a 10-1 order type (n-dodecane) are used depending on the usage environment. In addition, when used in areas with styrene-based plastics, n-dodecane (for example, 50% high-impact polystyrene Mitsubishi Monsanto Chemical Co., Ltd. "HT-58 Natural"), which has the most advantageous critical strain of polystyrene, is recommended.
), it is appropriate that the allowable critical strain is 0.26%, which has relatively little influence.

As shown in FIG. 4, if a felt 16 impregnated with liquid paraffin is attached to the brush base 2 or commutator sliding part 3, it will help damp the vibrations of the brush, and the vibrations of the brush will reduce the appearance of the liquid paraffin. Since the upper surface area increases, areas of low vapor pressure can be covered.

(Effects of the Invention) As explained above, according to the present invention, a member impregnated with liquid paraffin is installed near the commutator sliding part inside the motor housing and the bracket, and the paraffin vapor By adhering to the sliding parts and acting as a lubricant, it is possible to prevent abnormal wear of the sliding parts and scratch damage to the surface of the commutator segment, and also to reduce the generation of electrical noise. The quality of the product can be improved and the service life can be significantly extended.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a conventional example, and FIGS. 2(a) to (c) are
A diagram showing the configuration of a conventional commutator sliding part, respectively.
FIGS. 3 and 4 are configuration diagrams of embodiments of the present invention, respectively. 2... Brush base, 3... Commutator sliding part, 4... Commutator segment, 14... Bracket, 15...
Housing, 16... Felt impregnated with liquid paraffin.

Claims (1)

[Claims] In a small motor equipped with a brush having a brush base made of a thin plate-shaped metal elastic body and a commutator sliding part extending from the brush base or fixed to the tip of the brush base, A small motor characterized in that a member impregnated with liquid paraffin is installed near the commutator sliding part, on the brush base, or on the commutator sliding part.