JP2659869B2 - 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 bearing having a short cylindrical retainer for rotatably holding a plurality of balls.

[0003]

2. Description of the Related Art In a scanner motor used for a laser beam printer, for example, 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. The ball 3 is arranged so as to be rollable in the ball insertion recess 1.

[0004] A grease retaining portion 4 is formed at one end of the retainer 2 between the ball insertion recesses 1 and 1, and grease 5 for lubrication is injected into the grease retaining portion 4. The grease 5 is generally composed of a base oil (base oil) and a thickener having a relatively high viscosity. And
This type of scanner motor has a vertical axis with the rotation axis directed vertically and rotates at high speed (for example, 8000 to 150).
00 rpm).

[0005]

However, in the conventional configuration, when the motor is rotating, the speed fluctuation rate (referred to as jitter) may greatly change instantaneously as shown in FIG. Was. Such a large change in the rate of fluctuation causes fluctuations in the image of the laser beam printer.

The present invention has been made in view of the above circumstances, and 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]

The present invention SUMMARY OF THE INVENTION comprises a bearing having a cylindrical retainer for holding rollably plurality of balls in the ball insertion recess respectively, the axial direction of the retainer
A grease retaining portion is formed at the end of the ball insertion concave portion on the open portion side end of the motor, and the grease retaining portion is connected to two adjacent walls of the adjacent ball insertion concave portion.
And at least an outer side provided on the outer peripheral side between these two walls
It is characterized in that the periphery is substantially surrounded by the surrounding wall constituted by the wall .

It is preferable to use a porous material or a net-like member for the surrounding wall of the grease retaining portion, or to form a slit in the surrounding wall.

[0010]

The present inventor has investigated the cause of the instantaneous large change in the speed fluctuation rate in the conventional configuration, and has found out the following. When the motor rotates, the grease flows out of the grease retaining portion due to centrifugal force and the like accompanying the rotation, and the grease flowing out may intrude more than necessary to the sliding surface of the ball. When the vehicle gets over the grease, an instantaneous fluctuation occurs, and as a result, the speed fluctuation rate changes instantaneously greatly.

Therefore, in the above-described means, the grease retaining portion is formed so as to be substantially surrounded by the surrounding wall, so that the grease can be prevented from flowing out of the grease retaining portion more than necessary, and the grease can be removed by the ball. More than necessary can be prevented.

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

When used at low speeds, it is expected that the grease base oil will not be easily supplied to the ball side. However, a porous material or a net-like member may be used for the surrounding wall forming the grease retaining portion. Alternatively, by forming a slit in the surrounding wall, the base oil can be easily supplied to the ball side.

[0014]

1 to 5 show a first embodiment in which the present invention is applied to a scanner motor of a laser beam printer.
This will be described with reference to FIG. First, in FIG. 2 showing the overall configuration, a housing 11 has a container shape with an open top surface, and a cylindrical portion 12 extending upward is formed at the center of the bottom.
A bearing 13, which will be described later, formed of a rolling bearing is vertically provided on the inner peripheral portion of the cylindrical portion 12. A stator core 14 is provided on an outer peripheral portion 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 mounted on the bearing 1
3, 3 and 13 are rotatably supported in a state of being inserted vertically. The mirror mounting part 1 is provided above the rotating shaft 17.
8 is fitted, and 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 1
A preload boss 22 attached to the lower end of 7 is a preload spring disposed between the preload boss 21 and the lower bearing 13.

Since the upper and lower bearings 13 have the same configuration, the upper bearing 13 will be described in detail with reference to FIG. 1 in this case. 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, for example, plastic is disposed between the outer ring 23 and the inner ring 24. The retainer 25 has an upper surface and an inner surface as shown in FIGS. Ball insertion recess 2 with open outer surface
6 are formed at equal intervals in this case, and at the upper end thereof (of the ball insertion recess 26 among the axial ends).
A grease retaining portion 27 is formed on each of the ball insertion recesses 26 at an end of the opening portion) . Each grease retaining part 27
Are adjacent walls 26a, 26 of adjacent ball insertion recesses 26.
The surroundings are surrounded by a surrounding wall 29 composed of a and an inner side wall 28a and an outer side wall 28b formed so as to connect them to the inner peripheral side and the outer peripheral side between them.

A ball 30 is inserted into each of the ball insertion recesses 26, and each ball 30 is held by a retainer 25 while the groove 23a of the outer ring 23 and the groove 24a of the inner ring 24 are provided.
Are provided so as to be able to roll between them. Grease 31 for lubrication is injected into each grease retaining portion 27. The grease 31 is generally composed of a base oil (base oil) and a thickener having a relatively high viscosity. The former uses mineral oil, and the latter uses metal soap (for example, calcium soap).

On the upper and lower sides 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 such that the grease retaining portion 27 faces upward.

In the above configuration, when the rotor 16 is rotated at a high speed, the grease 3 stored in the grease retaining portion 27
1 receives frictional heat associated with the rolling of the ball 30, and the grease 31 also exerts a centrifugal force associated with the rotation.

At this time, since the grease retaining portion 27 is in a state of being surrounded by the surrounding wall 29, the grease 3
Even if a centrifugal force acts on 1, the grease 31, particularly the thickener, is prevented from flowing out of the grease retaining section 27. As a result, it is possible to prevent the grease 31 from entering the rolling surface of the ball 30, particularly the thickener, so that the speed fluctuation rate of the motor does not greatly change as shown in FIG. It is possible to prevent the fluctuation of the speed fluctuation rate from occurring in the image of the beam printer. In addition, the grease retaining portion 27 is
By being surrounded by
When injecting grease 31 into grease retaining section 27, grease 3
The protrusion of 1 from the outside can be prevented as much as possible.

The inner wall 28a of the surrounding wall 29 of the grease retaining portion 27 is provided in order to prevent the grease 31 from protruding when the grease 31 is injected into the grease retaining portion 27. May be provided as needed.

In this case, since the grease retaining portion 27 is in a state of being 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 centrifugal force accompanying rotation, there is no problem in the lubrication effect.

FIG. 6 shows a second embodiment of the present invention. The second embodiment differs from the first embodiment in the following points. That is, of the surrounding wall 29 of the grease retaining portion 27, the inner wall 3
7a and the outer wall 37b are formed of a 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 provided.
Among them, slits 38 are formed in the inner wall 28a and the outer wall 28b, respectively.

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

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

The grease retaining portion 27 does not necessarily need to be directed upward, and may be directed downward depending on the viscosity of the grease.

[0029]

As is apparent from the above description, according to the motor according to the first aspect, the grease retaining portion formed on the retainer is formed by two adjacent walls of the adjacent ball insertion recesses.
At least the outer wall provided on the outer peripheral side between these two walls
The grease injected into the grease retaining portion can be prevented from flowing out more than necessary, particularly the thickener component, by forming the surroundings to be substantially surrounded by the surrounding wall configured , thereby reducing the speed fluctuation rate of the motor. Has an excellent effect of preventing a large change in

According to the motor of the second, third, and fourth aspects, a porous material or a mesh member is used for the surrounding wall of the grease retaining portion, or a slit is formed in the surrounding wall.
While preventing outflow of the thickener component of grease,
The base oil can be easily supplied to the ball side, and the lubricating effect can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part showing a first 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.

FIG. 4 is a partially broken side view of the retainer.

FIG. 5 is a characteristic diagram showing a change in a speed fluctuation rate.

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

FIG. 7 is a view corresponding to FIG. 3, showing a third embodiment of the present invention.

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

FIG. 9 is a perspective view of a conventional retainer.

FIG. 10 is a partial side view of the retainer.

FIG. 11 is a characteristic diagram showing a change in a speed fluctuation rate in a 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, 26 is a ball insertion recess, 26a is a wall,
27 is a grease retaining portion, 28a is an inner wall, 28b is an outer wall,
29 is a surrounding wall, 30 is a ball, 31 is grease, 37a is an inner wall (porous material), 37b is an outer wall (porous material), 3
8 denotes a slit, 39a denotes an inner wall (net-like member), and 39b denotes an outer wall (net-like member).

Claims (4)

(57) [Claims] 1. A plurality of balls are respectively inserted into ball insertion recesses.
Part comprising a bearing having a cylindrical retainer rollably retained in, the ball of the end portion in the axial direction of the retainer
In a motor in which a grease retaining portion is formed at the end of the insertion concave portion on the opening side , the grease retaining portion is connected to an adjacent boad.
Two adjacent walls of the insertion recess and at least these two walls
An outer wall provided on the outer peripheral side between
A motor formed so that its periphery is substantially surrounded by walls . 2. The surrounding wall of the grease retaining part , at least
The motor according to claim 1, wherein a porous material is used for an outer side wall . 3. The surrounding wall of the grease retaining part , at least
2. A slit is formed in an outer side wall.
Motor as described. 4. At least one of the surrounding walls of the grease retaining portion
The motor according to claim 1, wherein a net-like member is used for the outer side wall .