JP2000232753A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the rotor of a motor having grooves on the outer periphery of its shaft or in the inner periphery of its bushing to be rotated satisfactorily, in both forward and backward directions. SOLUTION: First oblique grooves 25 ascending toward right side and second oblique grooves 26 ascending toward left side are provided on outer periphery of a rotating shaft 19 inserted into a bushing 16, so that the grooves 25 and 26 intersect each other. Oil is injected into the space between the inner periphery of the bushing 16 and the outer periphery of the shaft 19. Since the grooves 25 and 26 are inclined by approximately the same amount in the opposite directions and intersect each other, the conditions of the generated pressure, etc., become approximately equal, even through the direction of rotation of the rotating shaft 19 may be either in the forward direction or backward direction. Therefore, a rotor 18 and in turn, a polygon mirror 23 can be rotated satisfactorily in both forward and reverse directions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor having a structure in which a groove is provided in an outer peripheral portion of a shaft or an inner peripheral portion of a bearing cylinder into which the shaft is inserted.

[0002]

Conventionally, in a motor, a herringbone-shaped groove is provided in an outer peripheral portion of a rotating shaft as an axis or an inner peripheral portion of a bearing cylinder into which the rotating shaft is inserted, so that the rotating shaft can rotate. There is a type that employs a dynamic pressure bearing structure in which a rotary shaft is supported using pressure (dynamic pressure) generated based on the dynamic pressure.

FIG. 7 shows an example of such a bearing structure. In FIG. 7, a herringbone-shaped groove 3 is provided on the outer peripheral portion of the rotating shaft 2 inserted into the bearing cylinder 1. The grooves 3 are provided at two positions in the axial direction of the rotating shaft 2. In this device, when the rotating shaft 2 is rotated in the direction of arrow A, the fluid (oil or air) between the rotating shaft 2 and the bushing 1 collects at the base of the groove 3 so that the rotating shaft 2 Are supported in the bushing 1.

In the above-described conventional configuration, when the rotating shaft 2 is rotated in the direction opposite to the arrow A, the pressure balance is poor and the rotating shaft 2 does not rotate properly. The rotation direction is limited to one direction of arrow A.

For example, in the case of a polygon mirror driving motor, the rotation direction of the mirror is one direction, but when the mounting direction of the motor is upside down, it is necessary to rotate the rotating shaft in the reverse direction. In such a motor adopting the above-described bearing structure (having the herringbone-shaped groove 3), the rotating shaft 2 or the bearing cylinder 1 in which the herringbone-shaped groove 3 is formed in the opposite direction is required. Becomes

In view of the above, there is a demand for a motor having a structure in which a groove is provided in an outer peripheral portion of a shaft or an inner peripheral portion of a bearing cylinder into which the shaft is inserted, and which can rotate the rotor satisfactorily in both forward and reverse directions. Have been.

The present invention has been made in view of the above circumstances, and has as its object to provide a structure in which a groove is provided in an outer peripheral portion of a shaft or an inner peripheral portion of a bearing cylinder into which the shaft is inserted. It is an object of the present invention to provide a motor capable of favorably rotating a rotor in both forward and reverse directions.

[0008]

In order to achieve the above object, a first aspect of the present invention is a motor having a structure in which a shaft is inserted into a cylindrical bearing cylinder and a rotor is rotatably supported. In the outer peripheral portion of the shaft or the inner peripheral portion of the bearing sleeve, a plurality of parallel first oblique grooves each inclined to one side with respect to the axial direction of the shaft, On the opposite side to the first diagonal groove, there are provided a plurality of parallel second diagonal grooves which are inclined to the same degree as the first diagonal groove and intersect with the first diagonal groove. Is what you do.

In the above configuration, when the rotor rotates,
The shaft and the bush rotate relative to each other, and the flow of fluid along the first and second oblique grooves causes pressure to be generated between the shaft and the bush. The child starts to rotate stably. In this case, the first oblique groove and the second oblique groove
Since the direction of inclination is opposite to and inclined to the same degree as the diagonal groove, even if the rotor rotates forward or backward, the conditions such as the generated pressure are almost the same. Therefore, the rotor can be favorably rotated in both the forward and reverse directions.

In this case, one of the outer peripheral portion of the shaft and the inner peripheral portion of the bearing cylinder provided with the first and second oblique grooves is orthogonal to the axial direction of the shaft, and Second
May be provided with a plurality of parallel transverse grooves intersecting the oblique grooves. According to this, in addition to the first and second oblique grooves, there are transverse grooves intersecting with the first and second oblique grooves, and since the transverse grooves extend along the rotation direction of the rotor, the flow of the fluid becomes smoother, Rotation of the rotor in both the forward and reverse directions is further stabilized.

The bearing cylinder may be an oil-impregnated bearing (the invention of claim 3), or may be a dynamic pressure bearing structure in which liquid exists between the inner peripheral portion of the bearing cylinder and the outer peripheral portion of the shaft. 4 invention). According to these, there is an advantage that the lubrication performance is improved and the life of the bearing can be extended. Further, the portions provided with the first and second oblique grooves may be present at a plurality of positions in the axial direction of the shaft (the invention of claim 5).

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to a motor for driving a polygon mirror will be described below with reference to FIGS. First, FIG. 1 showing the overall configuration
In the outer peripheral portion of the cylindrical housing 11,
A stator 12 and a printed circuit board 13 are fixedly provided below the stator 12. Stator 12
Is a stator core 1 fixed to the outer peripheral portion of the housing 11.
4 and a plurality of windings 1 wound around the stator core 14.
And 5. In addition, a cylindrical bearing cylinder 16 is provided in a fixed state on the inner peripheral portion of the housing 11,
A thrust bearing 17 is provided at a lower portion in the housing 11.

A rotary shaft 19 as a shaft of a rotor 18 is rotatably inserted into the bearing tube 16.
The lower end of 9 is supported by the thrust bearing 17. The rotor 18 includes a rotating shaft 19, a table 20 fixed to the upper end of the rotating shaft 19 in the drawing, a rotor yoke 21 fixed to the lower surface of the table 20 and having a container-like shape with an open lower surface, and a rotor yoke 21. Of the stator core 14 and a permanent magnet 22 provided so as to face the outer peripheral portion of the stator core 14 via a predetermined gap.
A polygon mirror 23 is attached to the table 20 by screws 24, and the polygon mirror 23 is configured to rotate integrally with the rotor 18.

By the way, the outer periphery of the rotating shaft 19 is shown in FIG.
As shown in FIG. 2, a plurality of parallel first inclines inclining in a right-up direction, which is one side with respect to the axial direction of the rotation shaft 19, respectively.
And a plurality of parallel second diagonal grooves 26 that are inclined in the left-upward direction, which are opposite to the first diagonal groove 25 with respect to the axial direction of the rotation shaft 19, intersect each other. It is provided to be. These first oblique grooves 25
And the second oblique groove 26 have opposite inclination directions, but have the same inclination angle with respect to the axial direction of the rotating shaft 19 (for example, 4 degrees).
(About 5 degrees). The first and second oblique grooves 25 and 26 are formed in a range corresponding to the axial length of the bearing cylinder 16. Oil, which is a liquid, is injected between the inner peripheral portion of the bearing cylinder 16 and the outer peripheral portion of the rotating shaft 19.

In the above configuration, when the rotating shaft 19 rotates with the rotation of the rotor 18, the fluid oil along the first and second oblique grooves 25 and 26 formed on the outer peripheral portion of the rotating shaft 19. As a result, a pressure (dynamic pressure) is generated between the rotating shaft 19 and the bearing cylinder 16, and the rotating shaft 19 and thus the rotor 18 are stably rotated by this pressure. In this case, a dynamic pressure bearing structure using oil as a fluid is provided.

In this case, the first diagonal groove 25 and the second diagonal groove 26 are inclined in the opposite directions, are inclined to the same degree, and intersect, so that the rotating shaft 19 rotates forward (for example, arrow B). Direction) or the reverse rotation (the direction opposite to arrow B), the conditions such as the generated pressure are almost the same, and therefore, the rotation shaft 19 and thus the polygon mirror 23 are favorably rotated in both the forward and reverse directions. Will be able to do it. Therefore, even when the motor is installed upside down and the rotating direction of the rotating shaft 19 is reversed, the motor can be used without using a rotating shaft with the groove reversed.

Here, when the motor of this embodiment was incorporated as a motor for driving a polygon mirror, and the characteristics of the motor were confirmed, the following results were obtained. That is,
At the time of rotation at 10,000 rpm, the current value was reduced by 100 mA as compared with a conventional motor (having a herringbone-shaped groove on the outer periphery of the rotating shaft). The value of rotation unevenness is
At 0.1%, it was almost the same as the conventional motor.

In this embodiment, a dynamic pressure bearing structure using oil as a lubricant between the bearing cylinder 16 and the rotary shaft 19 is employed, so that the lubrication performance is improved and the life of the bearing is extended. There is an advantage that can be lengthened.

FIG. 3 shows a second embodiment of the present invention. The second embodiment differs from the first embodiment in the following points. That is, in addition to the first and second oblique grooves 25 and 26, the outer peripheral portion of the rotating shaft 19 is orthogonal to the axial direction of the rotating shaft 19,
Parallel transverse grooves 27 intersecting with the oblique grooves 25, 26 of FIG.
Is provided. Each lateral groove 27 has a ring shape and intersects with the first oblique groove 25 and the second oblique groove 26 at the intersection.

According to the second embodiment, in addition to the first and second oblique grooves 25 and 26, there is a transverse groove 27 intersecting the first and second oblique grooves 25 and 26, and the transverse groove 27 extends along the rotation direction of the rotating shaft 19. Because of the extension, the flow of the fluid (oil) becomes smoother, and the rotation of the rotating shaft 19 in both the forward and reverse directions is further stabilized.

FIG. 4 shows a third embodiment of the present invention. The third embodiment differs from the first embodiment in the following points. That is, in the outer peripheral portion of the rotating shaft 19, the first and second diagonal grooves 25 and 26 are provided at a plurality of locations in the axial direction of the rotating shaft 19, in this case, at two upper and lower locations. With such a configuration, the same operation and effect as those of the first embodiment can be obtained.

FIG. 5 shows a fourth embodiment of the present invention. The fourth embodiment differs from the first embodiment in the following points. That is, the bearing cylinder 28 is formed of an oil-impregnated bearing, and the first and second diagonal grooves 25 and 26 are provided on the inner peripheral portion of the bearing cylinder 28. With such a configuration, the same operation and effect as those of the first embodiment can be obtained.

FIG. 6 shows a fifth embodiment of the present invention. The fifth embodiment differs from the first to fifth embodiments in the following points. That is, the bearing cylinder 29 and the housing 30 are integrated, and the first and second diagonal grooves 25 and 26 and the lateral groove 27 are provided on the inner peripheral portion of the bearing cylinder 29. With such a configuration, the same operation and effect as those of the second embodiment can be obtained.

Further, in each of the embodiments described above, a shaft rotation type motor is described. However, the present invention can be applied to a fixed shaft type (a type in which a bearing cylinder rotates with respect to a shaft).

The present invention is not limited to the above embodiments, but can be modified or expanded as follows. The fluid between the rotating shaft 19 and the bearing cylinders 16 and 29 may be a gas such as air. Also,
The motor of the present invention can be applied to a disk drive motor, a fan motor, and the like, in addition to the polygon mirror drive motor.

[0026]

As is clear from the above description, according to the motor of the present invention, the rotor is provided in the outer peripheral portion of the shaft or the inner peripheral portion of the bearing cylinder into which the shaft is inserted. Can be satisfactorily rotated in both forward and reverse directions.

[Brief description of the drawings]

FIG. 1 is an overall longitudinal sectional view showing a first embodiment of the present invention.

FIG. 2 is a front view of a rotating shaft.

FIG. 3 is a view corresponding to FIG. 2, showing a second embodiment of the present invention;

FIG. 4 is a view corresponding to FIG. 2, showing a third embodiment of the present invention;

FIG. 5 is a vertical cross-sectional view of a bearing cylinder part showing a fourth embodiment of the present invention.

FIG. 6 is a view corresponding to FIG. 5, showing a fifth embodiment of the present invention.

FIG. 7 shows a conventional configuration, and is a longitudinal sectional view of a rotating shaft and a bearing cylinder portion.

[Explanation of symbols]

11 is a housing, 12 is a stator, 16 is a bushing, 18
Is a rotor, 19 is a rotating shaft (axis), 23 is a polygon mirror, 25 is a first oblique groove, 26 is a second oblique groove, 27 is a lateral groove, 28 is a bearing cylinder (oil-impregnated bearing), 29 is a bearing cylinder , 30
Indicates a housing.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Katsuya Seko 3-3-9 Shimbashi, Minato-ku, Tokyo Toshiba Abu E Co., Ltd. F-term (reference) 3J011 AA04 AA20 BA02 CA03 JA02 KA02 KA03 MA03 MA03 5H605 BB05 BB19 CC04 DD09 EB06 EB17 EB38 GG04 5H607 AA04 BB01 BB09 BB14 BB17 CC01 CC05 FF01 GG01 GG09 GG15

Claims (5)

[Claims] 1. A motor having a structure in which a shaft is inserted into a cylindrical bearing cylinder and a rotor is rotatably supported, wherein an outer peripheral portion of the shaft or an inner peripheral portion of the bearing cylinder has a shaft of the shaft. A plurality of parallel first diagonal grooves inclined to one side with respect to the direction, and the same inclination as the first diagonal groove on the side opposite to the first diagonal groove with respect to the axial direction of the shaft. And a plurality of parallel second oblique grooves intersecting with the first oblique grooves. 2. An outer peripheral portion of the shaft or an inner peripheral portion of the bearing cylinder, in which the first and second oblique grooves are provided, each of which is orthogonal to the axial direction of the shaft and the first and second oblique grooves. 2. The motor according to claim 1, wherein a plurality of parallel transverse grooves intersecting the two oblique grooves are provided. 3. The motor according to claim 1, wherein the bearing cylinder is an oil-impregnated bearing. 4. The motor according to claim 1, wherein a fluid exists between the inner peripheral portion of the bearing cylinder and the outer peripheral portion of the shaft. 5. The portion where the first and second oblique grooves are provided,
The motor according to any one of claims 1 to 4, wherein the motor is provided at a plurality of positions in the axial direction of the shaft.