JPH0666316A - Dynamic pressure bearing device - Google Patents

Abstract

PURPOSE:To provide a dynamic pressure bearing device generating no galling phenomenon and maintaining good lubricity. CONSTITUTION:A rotary shaft 1 is rotatably coupled with a sleeve 2 fixed to an outer tube 5 and supported by a dynamic pressure fluid bearing. A rotor yoke 13 constituting a drive motor is fixed to the lower face of a flange 11 fixed to the rotary shaft 1, and a rotary polygon mirror 15 scanning a light beam is mounted on the upper face of the flange 11. Grease mixed with fine powder made of diamond powder having the diameter of 40-70Angstrom , for example, is filled in the coupling gap between the rotary shaft 1 and the sleeve 2. Even when the fine powder becomes a high temperature and the holding power of the bearing is reduced and vibration is applied from the outside, no galling phenomenon is generated, and good lubricity can be maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure bearing device in a rotating device of a deflection scanning device used in, for example, a laser beam printer.

[0002]

2. Description of the Related Art Conventionally, a hydrodynamic bearing which rotates in a non-contact manner has been used in a rotating device used in a laser beam printer or the like which rotates at high speed and with high precision. FIG. 4 is a cross-sectional view of such a rotating device, which shows a rotating shaft 1 and a sleeve 2.
Is rotatably fitted, and a fixed plate 4 provided with a thrust plate 3 is fixed to the outer cylinder 5 at the lower end of the sleeve 2. A shallow groove 6 is formed on the surface of the thrust plate 3 facing the lower end of the rotary shaft 1 to form a dynamic thrust bearing. Also,
Two herringbone-shaped shallow grooves 7 are engraved on the outer peripheral surface of the rotary shaft 1 in the sleeve 2 to form a dynamic pressure radial bearing. Further, a spiral shallow groove 8 is engraved on the outer peripheral surface of the rotary shaft 1 near the opening of the sleeve 2 so that the lubricating fluid can flow to the hydrodynamic bearing. A recess 9 and a small diameter hole 10 are provided on the inner peripheral surface of the sleeve 2 between the spiral shallow groove 8 and the upper herringbone shallow groove 7, and a liquid such as oil or grease is used as a lubricating fluid. When used, the stability of the hydrodynamic bearing is ensured.

On the other hand, a flange 11 is fixed to the upper part of the rotary shaft 1, and a rotor yoke 13 to which a drive magnet 12 is fixed is fixed to the lower part thereof. Further, the stator coil 14 is provided on the surface of the outer cylinder 5 facing the drive magnet 12.
Are arranged, and a drive motor is configured. Further, a rotary polygon mirror 15 is mounted on the upper surface of the flange 11, and a rotating device is configured as a whole.

[0004]

However, in the above-mentioned conventional example, when the ambient temperature of the dynamic pressure bearing rises, the temperature of the dynamic pressure fluid bearing portion becomes further higher, and when external vibration occurs, oil or grease is generated. However, there is a drawback in that the lubrication of the motor is deteriorated and a galling phenomenon occurs between the sleeve 2 and the shaft 1 to stop the rotation of the motor.

Particularly, recently, the demand for high-speed rotation of 15,000 rpm or more has increased, the current flowing through the stator coil 14 increases, and the bearing portion also generates heat. Therefore, the holding force of the bearing decreases as the viscosity of the grease decreases, and the galling phenomenon easily occurs between the rotating shaft 1 and the sleeve 2.

The object of the present invention is to prevent galling,
An object of the present invention is to provide a dynamic pressure bearing device that maintains good lubricity.

[0007]

To achieve the above object, a hydrodynamic bearing device according to the present invention has a shaft and a sleeve that are rotatably fitted to each other, and the outer peripheral surface of the shaft and the sleeve. A shallow groove is formed between the inner peripheral surface of the sleeve and the lubricating oil is injected into the fitting gap, and in a dynamic pressure bearing device having a dynamic pressure generating portion, the lubricating oil is injected into the fitting gap. Fine powder is mixed, or at least one of the shaft and the sleeve is coated with the fine powder.

[0008]

In the dynamic pressure bearing device having the above-mentioned structure, the fine oil powder is mixed in the lubricating oil injected into the fitting gap between the shaft and the sleeve, or at least one of the shaft and the sleeve is coated with the fine powder. , Prevents galling between the shaft and sleeve.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a cross-sectional view of the first embodiment, and the same reference numerals as those in FIG. Then, the grease G mixed with the fine powder P is injected into the fitting gap between the rotary shaft 1 and the sleeve 2.

When the grease G containing the fine powder P is injected into the gap between the rotating shaft 1 and the sleeve 2 as shown in FIG. However, even if added, the galling phenomenon does not occur due to the presence of the fine powder P, and good lubricity can be maintained.

FIG. 3 shows another embodiment. As a method of coating the fine powder P, for example, if electroless Ni-P plating is used, the fine powder P is sleeved as shown in FIG.
Can be coated with a plating layer C. The plating layer C can also be formed on the rotary shaft 1.

[0012] By doing so as well, when the holding force of the bearing is reduced at high temperature and vibration is applied from the outside, the galling phenomenon does not occur due to the presence of the fine powder P, and good lubricity is maintained. You can

The fine powder P is particularly effective when diamond having a lubricating effect is used. This diamond, for example, was
What is synthesized by exploding NT explosive (explosive substance) can be used. Further, the above-mentioned effect is further improved by using the shape of the fine-grained powder P as graphite diamond having diamond as a nucleus and graphite coated around the diamond.

The fine powder P is 40 to 7 which is an ultra fine grain.
By setting the particle size to about 0 angstrom, the viscosity resistance of the grease G is hardly increased, and the rise time until the rated rotation of the dynamic pressure bearing device at low temperature is almost the same as that of the unmixed grease. be able to.

[0015]

As described above, in the hydrodynamic bearing device according to the present invention, fine powder particles are mixed into the lubricating oil injected into the fitting gap between the shaft and the sleeve, or at least one of the shaft and the grease is coated. It is possible to prevent the galling phenomenon of the shaft and the sleeve when external vibration is applied at high temperature.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a bearing device according to an embodiment.

FIG. 2 is an enlarged sectional view of a bearing portion.

FIG. 3 is an enlarged view of a bearing portion of another embodiment.

FIG. 4 is a configuration diagram of a general dynamic pressure bearing device.

[Explanation of symbols]

 1 rotating shaft 2 sleeve 3 thrust plate 4 fixing plate 5 outer cylinder 6 flange 7 drive magnet 8 rotor yoke 9 stator coil 10 rotating polygon mirror G grease P fine grain powder C plating layer

Claims (3)

[Claims] 1. A shaft and a sleeve which are rotatably fitted to each other, a shallow groove is formed between an outer peripheral surface of the shaft and an inner peripheral surface of the sleeve, and lubricating oil is provided in a fitting gap. In a hydrodynamic bearing device having a hydrodynamic pressure injection portion, fine powder is mixed into the lubricating oil injected into the fitting gap, or at least one of the shaft or the sleeve is coated with the fine powder. A hydrodynamic bearing device characterized in that 2. The hydrodynamic bearing device according to claim 1, wherein the fine powder is diamond powder. 3. The hydrodynamic bearing device according to claim 1, wherein the fine powder has a particle size of 40 to 70 angstroms.