JP2642531B2 - motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor provided with a ball bearing having a cylindrical retainer for rotatably holding a plurality of balls.

[0003]

2. Description of the Related Art For example, a polygon mirror scanner motor used in a laser beam printer has a rotating shaft supported by ball bearings. This ball bearing is composed of an inner ring, an outer ring, a plurality of balls, and a retainer for rollingly holding these balls. FIG. 3 shows an example of the retainer.

In FIG. 3, a retainer 1 has a flat cylindrical shape, and has a ball insertion recess 2 for rollingly holding a ball (not shown). A grease reservoir 3 is formed in a portion of the end face of the retainer 1 located between the ball insertion recesses 2. Grease (not shown) for lubrication is applied and stored in the grease storing section 3. Such a scanner motor is generally driven to rotate at a high speed (for example, 8000 to 15000 rpm).

[0005]

In the above-described conventional configuration, grease is stored in the grease storage section 3 of the retainer 1, so that when the rotating shaft is rotated at a high speed, the grease in the grease storage section 3 is subjected to centrifugal force or the like. As a result, the water may flow out to the inner surface side of the outer race and be supplied to the rolling surface of the ball more than necessary. In this case, there is a problem that instantaneous fluctuation occurs when the ball gets over the grease, and as shown in FIG. 5, the speed fluctuation rate largely changes instantaneously.

Accordingly, an object of the present invention is to provide a motor capable of preventing a large change in the speed fluctuation rate.

[Structure of the Invention]

[0008]

According to the present invention, there is provided a motor comprising a ball bearing having a cylindrical retainer for rotatably holding a plurality of balls, wherein an inner ring, an outer ring, and a ball of the ball bearing are provided. Alternatively, at least one of the retainers is formed of a sintered metal impregnated with a lubricating oil .

[0009]

[0010]

According to the above means, the inner ring of the ball bearing,
Lubricate at least one of the outer ring, ball or retainer
Since formed by a sintered metal impregnated, this Shoyuime
The lubricating oil is supplied from the barrel. Therefore, there is no need to store grease in the retainer. Therefore, since the grease is not supplied to the rolling surface of the ball more than necessary, it is possible to prevent the speed fluctuation rate from largely changing.

[0011]

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a polygon mirror scanner motor of a laser beam printer will be described below with reference to FIGS. First,
In FIG. 2 showing the overall configuration, the housing 11 has a container shape with an open top surface, and has a cylindrical portion 12 extending upward at the center of the bottom. Ball bearings 1 to be described in detail later are provided at upper and lower ends of an inner peripheral portion of the cylindrical portion 12.
3, 13 are provided.

A stator core 14 is provided on the outer peripheral portion of the upper end of the cylindrical portion 12, and a stator coil 15 is wound around the stator core 14. Stator core 1
4 and the stator coil 15 constitute a stator 16.

On the other hand, the rotating shaft 18 of the rotor 17 is supported in a state where it is vertically inserted into the ball bearings 13 and 13. A mirror mounting part 19 is fitted on the upper part of the rotating shaft 18. The mirror mounting portion 19 includes
The cup-shaped rotor yoke 20 is screwed, and the rotor yoke 20 is housed in the housing 11 in the attached state. A rotor magnet 21 is provided on the inner peripheral surface of the rotor yoke 20. A pressurized boss 22 is attached to the lower end of the rotating shaft 18, and a pressurized spring 23 is provided between the pressurized boss 22 and the lower ball bearing 13.

The details of the ball bearing 13 will be described with reference to FIG. In FIG. 1, an annular groove 2 is provided on an outer peripheral surface of an inner race 24 fitted on the rotating shaft 18.
4a are formed. A groove 25a facing the groove 24a of the inner ring 24 is formed on the inner peripheral surface of the outer ring 25 fitted to the tubular portion 12. Here, the inner ring 24 and the outer ring 25 are formed of an oil-impregnated bearing member, for example, a sintered metal impregnated with lubricating oil.

A flat cylindrical retainer 26 is disposed between the outer ring 25 and the inner ring 24. The retainer 26 has substantially the same shape as the retainer 1 having the conventional configuration (see FIG. 3), and has a plurality of ball insertion recesses 27 formed therein. The balls 28 are inserted and arranged in the respective ball insertion recesses 27, whereby each ball 28 is held by the retainer 26 and the groove 25 a of the outer race 25 and the inner race 2.
4 and is provided so as to be able to roll between the grooves 24a.

On the upper and lower sides of the ball bearing 13, stop rings 29 and 30 are used to seal the seal plate 3.
1, 32 are attached.

According to the present embodiment having such a configuration, the inner ring 24 and the outer ring 25 of the ball bearing 13 are formed of a sintered metal impregnated with lubricating oil, which is an oil-impregnated bearing member. The lubricating oil contained therein is supplied to the rolling surface of the ball 28. Therefore, unlike the conventional configuration, there is no need to store grease in the retainer 26. Therefore, since grease is not supplied to the rolling surface of the ball more than necessary,
A large change in the speed fluctuation rate can be reliably prevented.

FIG. 4 is a graph showing an experimental result of measuring the speed fluctuation rate in the configuration of the present embodiment. FIG. 5 is a graph showing experimental results obtained by measuring the speed fluctuation rate in the conventional configuration. By comparing FIG. 4 and FIG. 5, it is understood that the present embodiment can prevent a large change in the speed fluctuation rate as compared with the conventional configuration.

In the above embodiment, the inner race 24 and the outer race 2
Although 5 is formed by the oil-impregnated bearing member, the invention is not limited to this, and at least one of the inner ring, the outer ring, the ball and the retainer may be formed by the oil-impregnated bearing member.

In the above embodiment, the inner race 24 and the outer race 25 are formed by oil-impregnated bearing members.
The inner ring and the outer ring are formed by ordinary bearing metal members,
The ball may be formed of ceramic.
In this case, the ceramic ball has sufficiently high abrasion resistance, so that lubricating oil can be eliminated. Therefore, since it is not necessary to store grease in the retainer, it is possible to prevent the speed fluctuation rate from largely changing.

At this time, not only the balls but also the inner ring, the outer ring or the retainer may be formed of ceramic. A bearing that does not use such lubricating oil is referred to as a dry bearing.

[0023]

Since the present invention is as described above, the following effects can be obtained.

In the motor according to the first aspect, at least one of the inner ring, the outer ring, the ball, and the retainer of the ball bearing is formed of sintered metal impregnated with lubricating oil, so that there is no need to store grease in the retainer. It is possible to prevent the speed fluctuation rate from largely changing.

[0025]

[Brief description of the drawings]

FIG. 1 is an enlarged longitudinal sectional view of a ball bearing showing one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the entire motor.

FIG. 3 is a perspective view of a retainer showing a conventional configuration.

FIG. 4 is a graph showing a change in a speed fluctuation rate in one embodiment of the present invention.

FIG. 5 is a graph showing a change in a speed fluctuation rate in a conventional configuration.

[Explanation of symbols]

13 is a ball bearing, 24 is an inner ring, 25 is an outer ring, 2
6 is a retainer, 28 is a ball.

Claims (1)

(57) [Claims] 1. A motor comprising a ball bearing having a cylindrical retainer for rotatably holding a plurality of balls, wherein at least one of an inner ring, an outer ring, a ball and a retainer of the ball bearing is lubricated with lubricating oil. A motor formed from a sintered metal impregnated .