JPS6360246B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a sintered oil-impregnated bearing that is particularly suitable for relatively small motors such as coreless motors.

This type of oil-impregnated bearing manufactured by powder metallurgy has the excellent advantage of being self-lubricating. This self-lubricating property is due to the oil impregnated in the bearing coming out into the gap between the shaft and the bearing as the shaft rotates, but if left as is, the impregnated oil will leak out over time, reducing the lubrication ability. This will cause Therefore, in order to prevent this decline in lubrication ability, when a sintered oil-impregnated bearing is used, an lubrication mechanism such as a felt material wrapped around the outer circumference has conventionally been attached.

However, in the case of small motors, it is extremely difficult to install such a lubrication mechanism both in terms of the available space and in terms of not impairing miniaturization. Therefore,
In the case of small-sized motors, unlike other types of motors, there is no lubrication mechanism attached, and the problem is that the lubrication ability eventually deteriorates within a short period of time.

I would like to clarify the purpose of the present invention by specifically explaining this point using the coreless motor shown in FIG. 1 as an example. Inside the casing 1, the oil-impregnated bearings 2 and 3 in question support the motor shaft 4, and these bearings 2 and 3 are themselves fixed to a resin support 5 by press fitting, etc. The resin support 5 is attached to the inner surface of the casing 1 by an iron core 6. On the other hand, a commutator 7 and a coil 8 are attached to the motor shaft 4 by press-fitting or the like.
The motor shaft 4 supported by the motor shaft 3 rotates simultaneously with the commutator 7 and the coil 8.

When the motor shaft 4 rotates in this manner, the oil impregnated in the bearings 2 and 3 expands due to the frictional heat between the bearings 2 and 3 and the motor shaft 4, and seeps into the contact area between them. . This produces the above-mentioned lubrication ability, but some of the seeped oil is scattered to the outside from the opening of the bearing hole due to the centrifugal force accompanying the rotation of the motor shaft 4. As a result, the inside of the casing is contaminated with oil, and the impregnated oil is rapidly consumed, resulting in poor lubrication performance in a short period of time, which causes seizing of the motor shaft 4 and other problems, resulting in problems in service life.

This invention was made in consideration of the above points, and can maintain sufficient lubrication ability for a long period of time, and does not require any new space. The present invention provides a sintered oil-impregnated bearing that does not impede miniaturization of the bearing.

Hereinafter, the contents of the present invention will be explained in detail with reference to the attached FIGS. 2 and 3.

In the sintered oil-impregnated bearing 9 of the present invention, as shown in FIG. 2, at least one of the end surfaces 9a and 9b on both sides of the bearing is chamfered at the intersection of the end surface and the bearing inner diameter surface 9c. The bearing is characterized in that a groove 11 is provided running from the chamfered portion 10 to the outer circumferential side of the bearing.

The chamfer 10 may be either tapered or rounded, but if it is tapered, it is preferably about 0.2 ^C or more in dimension. The angle of the chamfer 10 is normally 45°, but it can also be made smaller. The point is that the lubricating oil scattered from the rotating motor shaft can be caught, and the caught oil can be smoothly transmitted to the groove 11 side along the chamfered portion 10.

On the other hand, the groove 11 following the chamfer 10 has a flat bottom surface 11a and extends linearly in a plane perpendicular to the axial direction, and the bottom surface 11a extends from a position x where the chamfer 10 intersects the bearing inner diameter surface 9c. This is to hold the lubricating oil that has been drawn out and received by the chamfer 10, and as the amount of lubricating oil that has flowed into the groove 11 from the chamfer 10 increases, it is as shown by the broken line in FIG. It is guided to the outer peripheral end of the bearing 9 and held within the groove 11. Therefore,
Groove 1 as long as it does not impair its holding and guiding functions.
The shape of 1 is arbitrary, but from the point of view of workability, etc., it is preferable to form it in a straight line. In the case of a straight groove 11, the actual depth is 0.1 mm or more, and the width is the same as the bearing 9.
It is preferable to set the inner diameter of πD×(0.05 to 0.7) as D. Furthermore, the number of grooves 11 can be one or more (preferably 2 to 6), but in the case of multiple grooves, it is preferable to arrange them at equal angles along the circumferential direction. Of course.

In addition, in the case of the illustrated example, the chamfer 10 and the groove 11
are provided on both end surfaces 9a and 9b of the bearing 9, but when used in place of the bearings 2 and 3 in the coreless motor described above, chamfers 10 and 10 are provided on the side in contact with the resin support 5 or the casing 1. It is not necessary to provide the groove 11. Further, when the side of the end face is open, it is also more effective to use a washer 12 or the like as shown in FIG. 3 for more effective oil recovery. Note that the groove 11
The lubricating oil held within is absorbed from the groove 11,
The water leaks out through the internal cavity of the bearing 9 to the contact area with the motor shaft 4 and circulates inside the bearing 9. In other words, a lubricating oil circuit is formed: chamfer 10→groove 11→internal cavity of bearing 9→contact part with motor shaft 4→chamfer 10. Further, when the rotation of the motor shaft 4 stops, the temperature of the bearing 9 decreases, and the lubricating oil inside the bearing 9 contracts, so that the lubricating oil in the groove 11 is sucked into the inside of the bearing 9. Then, when the motor shaft starts rotating again, it comes out between the motor and the bearing 9 again. Furthermore, since the bottom surface 11a of the groove 11 is flat and extends from the position x where the chamfer 10 and the inner diameter surface 9c intersect to the outer peripheral end, a portion of the lubricating oil flows from the inner diameter surface 9c. It immediately enters the groove 11 and forms the chamfer 10 and inner diameter surface 9.
Groove 11 between the position x where it intersects with c and the outer peripheral edge
It is absorbed into the bearing from the bottom surface 11a of the bearing. At this time, since the groove 11 is not V-shaped but concave, the lubricating oil located on the surface of the bottom surface 11a is absorbed into the groove 1.
The lubricating oil collides with the groove wall constituting the bearing 1 and is absorbed therein, which has the effect of preventing the lubricating oil from scattering from the groove bottom surface 11a of the rotating bearing.

As described above, the sintered oil-impregnated bearing 9 according to the present invention
In this case, at least one end face 9a of the bearing,
By providing the chamfer 10 and groove 11 on the 9b portion, they serve as a lubrication mechanism, so problems such as oil stains and seizing that would otherwise occur without a lubrication mechanism can be reliably solved. This excellent effect can be obtained. In addition, without requiring extra space or processing such as drilling,
Since the lubricating oil circuit can be configured with a simple structure of forming the chamfer 10 and the groove 11, the bearing can be made smaller, and products using it, such as coreless motors, can be made smaller. can. In addition, the lubricating oil that has entered the groove can be efficiently absorbed into the bearing over the entire groove without scattering.

The present invention is particularly suitable for relatively small motors such as coreless motors, but can be widely applied to other motors.

Here, the effects of the present invention will be specifically clarified by briefly describing the results of mounting tests using coreless motors.

[Bearing used] Material: 9% Sn, 0.5% C, the rest is essentially Cu, density 6.9g/cc, oil content 21
%(volume). Dimensions: Outer diameter 8φ, inner diameter 3.2φ, thickness 4.7
mm.

[Test results] In the case of the conventional example without groove 11 (but with a 0.15 ^C chamfer on the inner diameter surface): Seizing occurred after 1500 hours of operation, and the inside of the casing was heavily contaminated with oil. Furthermore, at the end of this operation, the oil content had decreased to 9%.

In the case of the device of the present invention, which is similar to the example shown in FIG. 2 described above (width of each groove 11 is 0.5 mm, chamfer 10 is 0.4 ^C ): No seizure is observed even after 2500 hours of operation, and there is no oil stain inside the casing. . At the end of the operation, the oil content was 13% and it was still usable.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the configuration of a coreless motor using this type of bearing, and Fig. 2 shows an embodiment of the present invention, in which a is a front view and b is an X-
FIG. 3 is a sectional view taken along the Y line, and is a partial view showing the example in FIG. 2 in use. 9... Bearing according to the present invention, 9a, 9b... End face, 9c... Bearing inner diameter surface, 10... Chamfering, 11
……groove.

Claims (1)

[Claims] 1. In a sintered oil-impregnated bearing made of powdered sintered metal and impregnated with lubricating oil, at least one end face portion of both end faces in the axial direction,
A chamfer is formed at the intersection of the end surface and the inner diameter surface of the bearing, and a groove with a flat bottom surface extending from the chamfer to the outer peripheral end of the bearing extends linearly in a plane perpendicular to the axial direction. A sintered oil-impregnated bearing characterized in that the bottom surface of the groove extends from a position where the chamfer intersects with the inner diameter surface.