JPS6343021A - Fluid bearing cylinder device - Google Patents

Abstract

PURPOSE:To obtain a high-reliability fluid bearing cylinder device by providing a fine step on the outermost periphery of the end face of a fixed shaft in the fixed shaft having herringbone type groups on the upper section and the lower section of the outer periphery. CONSTITUTION:Herringbone type groups are formed on the upper section and the lower section of the outer periphery of a fixed shaft 11, and a lubricant 13 is put in a fine gap between a thrust plate 12 having a spiral group 12a machined by etching or the like and the end face of the fixed shaft 11, Accordingly, the spiral group 12a is provided on the face section of the thrust plate 12 facing the fixed shaft 11, and a fine step is provided on the outermost periphery of the end face of the fixed shaft 11, thus the lubricant 13 is retained for a long time against the centrifugal force via the capillary phenomenon by the surface tension.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hydrodynamic bearing cylinder device that can be used in a video tape recorder.

BACKGROUND OF THE INVENTION FIG. 2 shows a cross-sectional view of a conventional hydrodynamic bearing cylinder device. To explain this, 31 is a fixed shaft with herringbone-type groups formed above and below the outer circumference, 32 is a lower cylinder supporting the fixed shaft 31, and 33 is the fixed shaft 31.
A disk 34 coaxially rotating around the disk 34 has a spiral group formed by etching or the like, and a thrust plate 35 fixed to the disk 33.
' is a lubricant interposed in the minute gap between the fixed shaft 31 and the disk 33 and the minute gap between the end surface of the fixed shaft 31 and the thrust plate 34.

FIG. 3 is an enlarged view of the main parts of the fixed shaft 31, the thrust plate 34, and the lubricant 36.

The operation of the conventional hydrodynamic bearing cylinder device configured as described above will be described below.

When the disk 33 starts rotating by the motor, pressure is generated in the lubricant 36 in the herringbone group formed on the fixed shaft 31 due to the pumping action, and the disk 33 rotates stably without contacting the fixed shaft 31. This constitutes a radial bearing. Further, pressure is generated in the lubricant 35 in the spiral group of the thrust plate 34 due to the pumping action, causing the disk 33 to float in the direction of arrow A in FIG. 3, forming a thrust bearing.

Problems to be Solved by the Invention However, in the above configuration, the lubricant 35 that protrudes from the minute gap between the end faces of the thrust plate 34 and the fixed shaft 31 is caused by the centrifugal force generated by the thrust plate 34 rotating at the same time as the disk 33. The lubricant 35 gradually diffuses toward the outer circumference, causing an insufficient supply of the lubricant 35 to the minute gap between the thrust plate 34 and the fixed shaft 31. As a result, the end surfaces of the thrust plate 34 and the fixed shaft 31 are
This has had the problem of causing metal contact, which greatly impairs the reliability of the hydrodynamic bearing cylinder device.

In view of the above-mentioned problems, the present invention has developed a highly reliable hydrodynamic bearing cylinder device that prevents lubricant from spreading due to centrifugal force and enables replenishment of lubricant into a minute gap between a thrust plate and a fixed shaft end face over a long period of time. It provides:

Means for Solving the Problems In order to solve the above problems, the hydrodynamic bearing cylinder device of the present invention includes a fixed shaft having herringbone-type groups on the upper and lower sides of the outer periphery, and a lower cylinder supporting the fixed shaft. , comprising a disk coaxially rotating around the fixed shaft, and a thrust plate having a spiral group facing an end face of the fixed shaft in a direction perpendicular to the fixed shaft and fixed to the disk. However, the fixed shaft end face has a structure in which a minute step is provided at the outermost periphery.

The present invention provides a highly reliable fluid bearing cylinder device that prevents lubricant from dispersing due to centrifugal force and enables replenishment of lubricant over a long period of time into the minute gap between the end face of the thrust plate and the fixed shaft. This is to realize the following.

Embodiments Hereinafter, hydrodynamic bearing cylinder devices according to embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an enlarged view of main parts in an embodiment of the present invention.

In FIG. 1, reference numeral 11 indicates a fixed shaft with herringbone-type groups formed on the upper and lower sides of its outer periphery, 12 indicates a thrust plate having a spiral group 12a processed by etching, etc., and 13 indicates an end face of the fixed shaft 11 and the thrust plate 12. It is a lubricant that exists in the tiny gap between the

The hydrodynamic bearing of this embodiment is configured as described above.

The operation of the cylinder device is basically the same as that of the prior art example described above, so a description thereof will be omitted here.

As described above, in this embodiment, a spiral group is provided on the surface of the thrust plate facing the fixed shaft, and a minute step is provided at the outermost periphery of the end face of the fixed shaft. In the gap between the steps at the outermost periphery of the end face, the lubricant is retained against centrifugal force by capillary action due to surface tension, and the lubricant is replenished over a long period of time into the minute gap between the thrust plate and the end face of the fixed shaft. , which realizes a highly reliable hydrodynamic bearing cylinder device.

In this embodiment, the motor is a planarly opposed type motor, but it may be a circumferentially opposed type motor.

Effects of the Invention As described above, the present invention realizes a highly reliable hydrodynamic bearing cylinder device by providing a minute step at the outermost periphery of the fixed shaft end face.

[Brief explanation of the drawing]

Fig. 1 is an enlarged view of main parts of a hydrodynamic bearing cylinder device according to an embodiment of the present invention, Fig. 2 is an enlarged view of main parts of a conventional hydrodynamic bearing cylinder device, and Fig. 3 is an overall cross section of a conventional hydrodynamic bearing cylinder device. It is a diagram. 11...Fixed shaft, 12...Thrust plate, 12a...Spiral group, 13
······lubricant.

Claims (1)

[Claims] a fixed shaft having herringbone-type groups above and below the outer periphery; a lower cylinder supporting the fixed shaft; a disk coaxially rotating around the fixed shaft; A hydrodynamic bearing cylinder comprising a thrust plate having a spiral group facing the end face of the shaft and fixed to the disk, and having a minute step at the outermost periphery of the end face of the fixed shaft. Device.