JPH04145214A - Dynamic pressure bearing rotating device - Google Patents

Abstract

PURPOSE:To reduce the cost of manufacturing such as machining and assembling and obtain a stable bearing characteristic easily by disposing oil-contained material at the sleeve inner peripheral surface opposed to the outer peripheral surface of a shaft, and forming a protruding part of minute area around the center of the face opposed to one end part of the shaft. CONSTITUTION:A sleeve 21 is provided on its inner peripheral surface with a built-in second sleeve 22 formed of oil-contained material. A fixed plate 4 with a built-in thrust supporting member 41 forming a protruding part of minute area is disposed at the lower end part of the sleeve 21. The center area of the lower end face of a shaft 1 is supported by this minute-area protruding part of the thrust supporting member 41. Accordingly, when the shaft 1 is rotated, the radial direction is supported in the non-contact state by the dynamic pressure acting between the shaft 1 and the second sleeve 22. Since oil-contained material is used for the second sleeve 22, there is little possibility of generating oil shortage or the like.

Description

Detailed Description of the Invention [Field of Application in Industry A] The present invention relates to a hydrodynamic bearing rotation device, and relates to a hydrodynamic bearing rotation device used, for example, in a deflection scanning device used in a laser beam printer or the like. be.

[Prior Art] In recent years, there has been an increasing demand for rotating devices that rotate at high speed or with high precision. Particularly in laser beam printers and the like, hydrodynamic bearings that rotate without contact are being used to obtain high-precision rotating devices. It is used. On the other hand, there is also a high demand for cost reduction, and there is an increasing demand for cost reduction of hydrodynamic bearings.

FIG. 4 is a diagram showing a deflection scanning rotation device of a laser beam printer using a conventional hydrodynamic bearing.

In the figure, a rotating shaft 1 and a sleeve 2 are rotatably fitted. A thrust plate 3 is arranged at the lower end of the sleeve 2 together with fixed Fi and 4, and is fixed to an outer cylinder 5. A flange 6 is fixed to the rotating shaft 1, and a rotating polygon mirror 7 is fixed to the upper part of the flange 6. A yoke 9 to which a driving magnet 8 is fixed is fixed to the lower part of the flange 6.

A stator 10 fixed to the outer cylinder 5 is arranged at a position facing the driving magnet 8.

Here, a shallow groove 11 is cut into the thrust plate 3 on the surface facing the end of the rotating shaft 1, thereby forming a dynamic pressure thrust bearing. Also provided are holes 12 and grooves 13 for circulation of lubricating fluid. A herringbone-shaped shallow groove 14 is cut on the outer circumferential surface of the rotating shaft 1 at a position facing the inner circumferential surface of the sleeve 2, thereby forming a dynamic pressure radial bearing. moreover,
A shallow spiral groove 15 is formed near the sleeve opening on the outer peripheral surface of the rotating shaft 1 so that lubricating fluid flows toward the dynamic pressure thrust bearing. The sleeve 2 is provided with a recess 16 at a position between the herringbone-shaped shallow dipping 14 and the spiral shallow groove 15, and a small diameter hole 17. This ensures the stability of hydrodynamic bearings that use liquid (oil, grease, etc.) as the lubricating fluid.

[Problems to be Solved by the Invention] However, the above conventional example has the following drawbacks.

(1) In order to ensure characteristics and stability as a rotating device, the number of parts is large, and each part has a high precision and a complicated shape, resulting in high manufacturing costs such as processing and assembly.

(2) Unless lubricating fluid is maintained and air is prevented from entering, stable characteristics of the rotating device cannot be ensured.

On the other hand, in order to reduce costs, oil-impregnated bearings (sliding bearings)
If this is used, the gap in the oil-impregnated bearing portion causes whirling, making it impossible to satisfy the characteristics of a rotating device.

SUMMARY OF THE INVENTION In view of the problems in the conventional example described above, an object of the present invention is to provide a hydrodynamic bearing rotating device that can obtain stable rotation at low cost without making each component highly accurate and having a complicated shape. .

[Means and Effects for Solving the Problems] According to the present invention, an oil-impregnated material is arranged on the inner circumferential surface of the sleeve that faces the outer circumferential surface of the shaft, and a minute area is provided near the center of the surface that faces one end of the shaft. A convex portion is formed.

This allows each component to have a high precision and complicated shape, making it possible to obtain a stable rotating device at low cost.

[Example] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 shows a cross section of a dynamic pressure bearing rotation device according to an embodiment of the present invention. In the figure, the rotating shaft 1 and the second sleeve 22 are rotatably fitted to each other. The second sleeve 22 is incorporated into the inner peripheral surface of the first sleeve 21 and is made of an oil-impregnated material. A flange 6 is fixed above the rotating shaft in the figure, and a rotating polygon mirror 7 is fixed above the flange 6. Further, at a position where the outer circumferential surface of the rotating shaft 1 and the inner circumferential surface of the second sleeve 22 face each other, a herringbone-shaped shallow groove 14 is formed on either the rotating shaft 1 or the second sleeve 22 (in the embodiment). A hydrodynamic radial bearing is formed by engraving the rotary shaft 1). Furthermore, a shallow spiral groove 15 is similarly carved in the vicinity of the sleeve opening so that the lubricating fluid does not flow out from the opening so that the fluid flows downward in the figure.

A yoke 9 to which a driving magnet 8 is fixed is fixed to the lower part of the flange 6, and a stator 10 fixed to the outer cylinder 5 is arranged at a position facing the driving magnet 8.

On the other hand, as described above, the second sleeve 22 formed of an oil-impregnated material (for example, oil-impregnated sintered metal used in sliding bearings) is incorporated into the inner peripheral surface of the sleeve 21 . At the lower end of the sleeve 21, a fixed plate 4 incorporating a thrust support member 41 forming a convex portion with a small area is arranged. The vicinity of the center of the lower end surface of the rotating shaft 1 is supported by a small-area convex portion of the thrust support member 41.

Therefore, when the rotating shaft 1 is rotationally driven, the rotating shaft 1 and the second sleeve 22 are supported in a non-contact manner by the dynamic pressure acting between them in the radial direction. Here, the second
Since the sleeve 22 is made of an oil-impregnated material, there is less chance of oil leakage, etc., and even if an excessive load is applied, the action of the oil-impregnated bearing (sliding bearing) prevents seizing, etc., making it stable. A bearing can be configured.

In addition, in the thrust direction, since the lower end surface of the rotating shaft 1 is in contact with and supported by a small convex portion formed near the center of the opposing surface, the contact state is substantially close to point contact. Therefore, rotation loss and loss torque due to contact can be extremely reduced. Moreover, the characteristics as a rotating device can be obtained close to those of non-contact support.

Furthermore, the components of the thrust bearing are simple, and manufacturing costs for assembly and processing can be reduced.

If the thrust support member 41 is made of an oil-impregnated material similar to that of the second sleeve 22, it can also be expected to function as an oil-impregnated bearing (sliding bearing), preventing the occurrence of seizures, etc., and reducing torque loss, etc. becomes possible.

From the above, a more stable rotating device can be obtained.

Note that it is preferable that the lubricating fluid (oil, etc.) present in the bearing part be filled in the radial part and the thrust part.
The oil reservoir portion 23 that does not function as a bearing, the vicinity of the shallow groove 15 for preventing flow ratio of lubricating fluid, etc. do not necessarily need to be filled with lubricating fluid, and assembly can be easily performed.

FIG. 2 shows a cross section of a hydrodynamic bearing rotation device according to a second embodiment of the present invention. In this figure, the same members and the same functions as those in FIG. 1 are given the same numbers, and the description thereof will be omitted.

In the rotating device shown in FIG. 2, the first sleeve 24 incorporates a second sleeve 25 made of an oil-impregnated material and having a bag-like shape in which radial and thrust support members are integrated.

On the other hand, the shaft end (lower side in the figure) of the rotating shaft 1 has a spherical shape (stepped or conical shapes are also possible), and the contact state of the thrust support part can be obtained in the same manner as in the first embodiment. can.

By doing so, assembly becomes easier and costs can be reduced.

Note that the second sleeve 25 can be manufactured separately from the thrust support part 42 and then integrated by press-fitting or the like. In this case, the thrust support portion 42 may be made into a spherical shape or the like, and the shaft end surface of the rotating shaft 1 may be made flat.

FIG. 3 shows a cross section of a hydrodynamic bearing rotating device according to a third embodiment of the present invention. In this figure, the same members and the same functions as those in FIG. 1 are given the same numbers, and the description thereof will be omitted.

In the rotating device shown in FIG. 3, a thrust support member 51 made of an oil-impregnated material and protruding from the end surface of the rotating shaft is incorporated near the center of the shaft end surface of the rotating shaft 101, and a thrust support member 51 is incorporated into the rotating shaft 101.
It is designed to make contact with 3 in a minute area. Therefore, it can be easily manufactured by simply attaching an oil-impregnated material processed into a spherical shape or the like to the end surface of the rotating shaft 101.

In the above description, the case where the shaft is rotated has been described, but the same effect can be obtained also in the case where the shaft is fixed.

[Effects of the Invention] As explained above, according to the present invention, an oil-impregnated material is arranged on the inner circumferential surface of the sleeve that faces the outer circumferential surface of the shaft, and a minute area is provided near the center of the surface that faces one end of the shaft. Since the convex part is formed, each part has a high precision and complex shape, which reduces manufacturing costs such as processing and assembly, and makes it easy to obtain stable bearing characteristics. There is.

[Brief explanation of drawings]

1 is a sectional view of a hydrodynamic bearing rotation device according to a first embodiment of the present invention; FIG. 2 is a sectional view of a hydrodynamic bearing rotation device according to a second embodiment of the present invention; The figure is a sectional view of a hydrodynamic bearing rotation device according to a third embodiment of the present invention, and FIG. 4 is a sectional view of a conventional hydrodynamic bearing rotation device. 1. Rotating shaft, 2. Sleeve, 4. Fixed plate, 7. Rotating polygon mirror, 21: Second sleeve, 41 Thrust support member.

Claims (2)

[Claims] (1) It has a shaft and a sleeve that are rotatably fitted to each other, and a hydrodynamic radial bearing is configured between the outer peripheral surface of the shaft and the inner peripheral surface of the sleeve, and one end of the shaft In a hydrodynamic bearing rotating device that supports axial force, an oil-impregnated material is arranged on the inner circumferential surface of the sleeve facing the outer circumferential surface of the shaft, and an oil-impregnated material is arranged on one end surface of the shaft or near the center of the surface opposite the one end surface of the shaft. A hydrodynamic bearing rotating device characterized in that a convex portion with a minute area is formed on the surface. (2) A convex portion having a minute area formed near the center of one end surface of the shaft or a surface facing the one end surface of the shaft is formed of an oil-impregnated material. Pressure bearing rotating device.