JPH04344144A - Motor - Google Patents

Abstract

PURPOSE:To prevent out flow of grease poured in a grease reservoir more than required and to prevent a large change of a speed change rate in a motor in which the reservoir is formed at an end of a retainer. CONSTITUTION:In a bearing 13 for supporting a rotating shaft 17, a cylindrical retainer 25 for rotatably holding a plurality of balls 30 is arranged between an outer race 23 and an inner race 24. A grease reservoir 27 for storing grease 31 is formed at an end of the retainer 25. The reservoir 27 is formed in a state in which its periphery is surrounded by an enclosure wall 29.

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 equipped with a bearing having a short cylindrical retainer that rotatably holds a plurality of balls.

0003

2. Description of the Related Art For example, in a scanner motor used in a laser beam printer, a rolling bearing is used as a bearing for supporting a rotating shaft. In this rolling bearing, a short cylindrical retainer 2 having a plurality of ball insertion recesses 1 is disposed between an outer ring and an inner ring, for example as shown in FIGS. 9 and 10, and each of the retainers 2 is A ball 3 is rotatably disposed in a ball insertion recess 1.

A grease retainer 4 is formed at one end of the retainer 2 between the ball insertion recesses 1, 1, into which grease 5 for lubrication is injected. Grease 5 is generally composed of base oil and a thickener with relatively high viscosity. This type of scanner motor has a vertical axis with the rotation axis oriented in the vertical direction, and can rotate at high speed (for example, 8000 to 1500
It is generally used at 0 rpm).

[0005]

However, in the conventional structure, when the motor rotates, the speed fluctuation rate (referred to as jitter) may change instantaneously and greatly as shown in FIG. Ta. If the speed fluctuation rate changes greatly in this way, it would appear as fluctuations in the image of the laser beam printer.

The present invention has been made in view of the above circumstances, and its object is to provide a motor that can prevent the rate of speed fluctuation from changing significantly.

[Configuration of the invention]

[0008]

[Means for Solving the Problems] The present invention provides a motor that includes a bearing having a cylindrical retainer that rotatably holds a plurality of balls, and a grease retaining portion is formed at the end of the retainer. The grease retaining portion is formed in such a manner that its periphery is substantially surrounded by a surrounding wall.

[0009] It is preferable to use a porous material or a net-like member for the surrounding wall of the grease reservoir, or to form slits in the surrounding wall.

0010

[Operation] By the way, the present inventor investigated the cause of the instantaneous large change in speed fluctuation rate in the conventional configuration and found the following. This is because when the motor rotates, grease may flow out of the grease reservoir due to centrifugal force caused by the rotation, and the flowed out grease may enter the sliding surface of the ball in excess of the necessary amount. An instantaneous fluctuation occurs when the motor overcomes the grease, and as a result, the rate of speed fluctuation changes instantaneously and greatly.

[0011] Therefore, in the above-mentioned means, by forming the grease retaining part in a form in which the periphery is substantially surrounded by the surrounding wall, it is possible to prevent grease from flowing out from the grease retaining part more than necessary, and as a result, the grease can be prevented from flowing out into the ball. This can prevent more than the required amount from entering the rolling surface of the wheel.

In this case, when the motor rotates, the base oil portion of the grease is supplied to the ball side by the centrifugal force accompanying the rotation, so there is no problem with the lubricating effect of the grease.

Furthermore, when used at low speed rotation, it is expected that it will be difficult for the base oil component of the grease to be supplied to the ball side. Alternatively, by forming slits in the surrounding wall, the base oil can be easily supplied to the ball side.

[0014]

[Embodiment] A first embodiment in which the present invention is applied to a scanner motor of a laser beam printer will be described below with reference to FIGS. 1 to 5.
Explain with reference to. First, in FIG. 2 showing the overall configuration, the housing 11 has a container shape with an open top, and a cylindrical portion 12 extending upward is formed at the center of the bottom. Bearings 13, which will be described later and are made of rolling bearings, are provided on the upper and lower sides of the inner peripheral portion of the cylindrical portion 12. A stator core 14 is provided on the outer periphery of the cylindrical portion 12, and a stator coil 15 is wound around the stator core 14.

The rotating shaft 17 of the rotor 16 is connected to the bearing 13
, 13 and is rotatably supported in a vertically inserted state. At the top of this rotation shaft 17 is a mirror mounting section 18.
The rotor yoke 19 screwed to the mirror mounting portion 18 is housed in the housing 11. A rotor magnet 20 is provided on the inner peripheral surface of the rotor yoke 19. In addition, 21 is the rotating shaft 17
A preload boss 22 is attached to the lower end of the preload boss 2.
1 and the lower bearing 13.

Since the above-mentioned upper and lower bearings 13 have the same structure, in this case, the upper bearing 13 will be described in detail with reference to FIG. 1 as a representative. An annular groove 23a is formed on the inner peripheral surface of the outer ring 23, and an annular groove 24a facing the groove 23a is formed on the outer peripheral surface of the inner ring 24.

A cylindrical retainer 25 made of plastic, for example, is disposed between the outer ring 23 and the inner ring 24, and as shown in FIGS. 3 and 4, the retainer 25 has an upper surface and an inner surface. Ball insertion recess 2 with open outer surface
6 are formed at equal intervals, eight in this case, and a grease retainer 27 is formed at the upper end between the ball insertion recesses 26. Each grease retaining portion 27 includes walls 26a, 26a of adjacent ball insertion recesses 26, and an inner wall 28a and an outer wall 28 formed so as to connect therebetween.
The periphery is surrounded by an encircling wall 29 consisting of b.

A ball 30 is inserted into each ball insertion recess 26 , and each ball 30 is held in the retainer 25 between the groove 23 a of the outer ring 23 and the groove 24 a of the inner ring 24 .
It is rotatably installed between the Lubricating grease 31 is injected into each grease retaining portion 27. The grease 31 is generally composed of a base oil and a relatively high viscosity thickener, with mineral oil being used for the former and metal soap (for example, calcium soap) being used for the latter.

Furthermore, on the upper and lower surfaces of the bearing 13,
Seal plates 34 and 35 are attached by stop rings 32 and 33. The bearing 13 having such a configuration is arranged so that the grease retaining portion 27 faces upward.

In the above-described configuration, when the rotor 16 is rotated at high speed, the grease 3 stored in the grease storage portion 27
1 receives frictional heat due to the rolling of the ball 30, and centrifugal force due to the rotation also acts on the grease 31.

At this time, since the grease retaining portion 27 is surrounded by the surrounding wall 29, the grease 3
Even if a centrifugal force acts on the grease 31, the thickening agent in particular is prevented from flowing out from the grease reservoir 27. This prevents the grease 31, especially the thickener component, from entering the rolling surface of the balls 30, as shown in FIG.
As shown in FIG. 2, the speed fluctuation rate of the motor does not change greatly, and it is possible to prevent fluctuations from occurring in the image of the laser beam printer due to changes in the speed fluctuation rate. Furthermore, since the grease retaining portion 27 is surrounded by the surrounding wall 29, when the grease 31 is injected into the grease retaining portion 27, the grease 31
It is possible to prevent as much as possible from protruding outside.

Here, of the surrounding wall 29 of the grease retaining portion 27, the inner wall 28a in particular is provided to prevent the grease 31 from protruding when injected into the grease retaining portion 27; may be provided as necessary.

In this case, since the grease retaining portion 27 is surrounded by the surrounding wall 29, there is a concern that the lubricating component will not be supplied to the ball 30 side. Since a certain low-viscosity base oil component is supplied to the rolling surface side of the ball 30 by the centrifugal force accompanying the rotation, there is no problem with the lubrication effect.

FIG. 6 shows a second embodiment of the present invention, which differs from the first embodiment described above in the following points. That is, the inner wall 37 of the surrounding wall 29 of the grease retaining portion 27
a and the outer wall 37b are made of porous material.

FIG. 7 shows a third embodiment of the present invention. In this embodiment, the surrounding wall 29 of the grease retaining portion 27 is
A slit 38 is formed in each of the inner wall 28a and the outer wall 28b.

Furthermore, FIG. 8 shows a fourth embodiment of the present invention, in which the surrounding wall 2 of the grease retaining portion 27 is
9, the inner wall 39a and the outer wall 39b are formed of a net-like member.

In these second, third, and fourth embodiments, while preventing the thickener component of the grease 31 from flowing out, the base oil component can be easily supplied to the ball 30 side, and the lubrication effect can be improved. Therefore, it is suitable for use in low-speed rotation.

It should be noted that the grease retaining portion 27 does not necessarily have to face upward, but may face downward depending on the viscosity of the grease.

[0029]

As is clear from the above description, according to the motor according to claim 1, the grease retaining portion formed in the retainer is formed in such a manner that the periphery thereof is substantially surrounded by the surrounding wall, so that the grease can be easily removed. It is possible to prevent the grease injected into the retaining part, especially the thickener component, from flowing out more than necessary, and this has the excellent effect of preventing a large change in the speed fluctuation rate of the motor.

Further, according to the motor according to claims 2, 3, and 4, by using a porous material or a net-like member for the surrounding wall of the grease retaining portion, or by forming a slit in the surrounding wall,
While preventing the thickener component of the grease from flowing out,
The base oil can be easily supplied to the ball side, improving the lubrication effect.

[Brief explanation of drawings]

[Fig. 1] A vertical cross-sectional view of essential parts showing a first embodiment of the present invention.

[Figure 2] Longitudinal cross-sectional view of the entire motor

[Figure 3] Perspective view of retainer

[Figure 4] Partially cutaway side view of retainer

[Figure 5] Characteristic diagram showing changes in speed fluctuation rate

FIG. 6 is a diagram corresponding to FIG. 3 showing a second embodiment of the present invention.

[Figure 7] Third aspect of the present invention
A diagram corresponding to FIG. 3 showing the embodiment

FIG. 8 is a diagram corresponding to FIG. 3 showing a fourth embodiment of the present invention.

[Fig. 9] Perspective view of a conventional retainer

[Figure 10] Partial side view of retainer

[Figure 11] Characteristic diagram showing changes in speed fluctuation rate in the conventional configuration

[Explanation of symbols]

13 is a bearing, 16 is a rotor, 23 is an outer ring, 24 is an inner ring,
25 is a retainer, 27 is a grease retaining part, 28a is an inner wall,
28b is an outer wall, 29 is a surrounding wall, 30 is a ball, 31 is a grease, 37a is an inner wall (porous material), 37b is an outer wall (porous material), 38 is a slit, 39a is an inner wall (reticular member) , 39b indicates an outer wall (reticular member).

Claims (4)

[Claims] 1. A motor comprising a bearing having a cylindrical retainer that rotatably holds a plurality of balls, and a grease retainer formed at an end of the retainer, the grease retainer comprising: A motor characterized in that its periphery is substantially surrounded by a surrounding wall. 2. The motor according to claim 1, wherein a porous material is used for the surrounding wall of the grease reservoir. 3. The motor according to claim 1, wherein a slit is formed in the surrounding wall of the grease retaining portion. 4. The motor according to claim 1, wherein a net-like member is used for the surrounding wall of the grease retaining portion.