JP2505124Y2 - Hydrodynamic bearing - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a hydrodynamic bearing for supporting a rotary shaft used in a rotary drive device of electric equipment, office equipment and the like.

[Conventional technology]

In audio equipment, VCRs, office equipment, etc., a herringbone groove, a spiral groove, or a parallel groove is formed on the surface of a rotating shaft that rotates at a high speed or the surface of a sleeve that supports the rotating shaft so that air generated by pumping action during rotation or A hydrodynamic bearing that utilizes dynamic pressure of lubricating oil or the like is used. Such a hydrodynamic bearing requires a space for accumulating water or oil for lubrication, but a conventional hydrodynamic bearing normally faces the rotating shaft surface or the inner surface of the cylindrical body into which the rotating shaft is fitted. It has a structure that retains lubricating oil on the surface. That is, as shown in FIGS. 6 and 7, the dynamic pressure groove of the rotary shaft 11
The inner diameter between the dynamic pressure groove 11a and the dynamic pressure groove 11b on the sleeve 13 side into which the rotary shaft 11 is fitted is increased by slightly reducing the diameter between the dynamic pressure groove 11b and 11a. Tesumi 12
May be formed to form the lubricating oil reservoir.

Alternatively, as disclosed in Japanese Utility Model Laid-Open No. 59-128924 and Japanese Patent Laid-Open No. 63-243521, the bottom surface of the cylinder into which the rotary shaft is inserted is closed to close the gap between the rotary shaft and the cylinder with lubricating oil. There is also one.

[Problems to be solved by the device]

One of the important roles of the lubricant 12 formed on the inner surface of the cylindrical body into which the rotary shaft of the hydrodynamic bearing or the rotary shaft is fitted is as a supply source of the lubricating fluid (oil, grease, water, etc.). Has the role of. However, even if the slippery part is filled with the lubricating fluid as in the conventional case, only a small amount near the inlet of the bearing is actually replenished for lubrication, and most of them are accumulated or leaked as they are, and the replenishment efficiency is poor. It was This invention has been made to solve such a problem.

[Means for solving the problem]

That is, in order to solve the above problems, the present invention forms a dynamic pressure groove on the surface of a rotary shaft or an inner surface of a sleeve into which the rotary shaft is fitted, and forms a lubricating fluid filling groove near the dynamic pressure groove. In the hydrodynamic bearing, the smoothness is formed on the rotary shaft in a smooth curved shape, and a smooth curve is formed from the curved bottom (the minimum position of the shaft diameter) to the vicinity of the dynamic pressure groove. It is characterized by being shaped like a squirrel.

Alternatively, it is characterized in that the vicinity of the bottom of the mouse is a smooth curve-shaped mouse and a straight run up from the end of the curved portion near the bottom to the shaft surface.

[Action]

With the above means, when the rotating shaft rotates, r is an arbitrary axial radius of the surface of the slime formed on the shaft surface,
The centrifugal force f there is f, where ω is the rotational angular velocity of the rotating shaft.
= M · ω ² · r, the centrifugal force f increases as it approaches the shaft surface, and the lubricant acts on the shaft surface in the direction of the dynamic pressure groove, and the lubricating oil gradually moves to the dynamic pressure. Move in the groove direction. In this way, the lubricating oil is supplied to the dynamic pressure groove without waste.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a main part of a rotary shaft of a hydrodynamic bearing of the present invention. Herringbone type dynamic pressure grooves 1a and 1b are formed on the surface of the rotary shaft 1, and between these two dynamic pressure grooves 1a and 1b, there is a smooth curve-shaped groove 2 over the entire surface. Has been formed. The curve shape of the mouse 2 is preferably an arc shape or an elliptic arc shape, but is not limited thereto, and may be, for example, a hyperbolic shape or a parabolic shape. When the mouse 2 is provided in this manner, the shape of the mouse 2 is shown in FIG.
It is also conceivable to form a V-shaped gullet 2'having a chevron shape with a sharp center as shown in FIG. However, if such a shape is used, there is a problem of stress concentration, so that the range of d near the bottom 2a is made a part of a smooth curved arc or elliptic arc as shown in FIG. May be a straight line.

Thus, when the rotating shaft 1 rotates, if the arbitrary radius of the surface of the smooth curve-shaped slot 2 formed on the surface of the rotating shaft is r, the centrifugal force f there is the rotational angular velocity of the rotating shaft ω. Is expressed by f = m · ω ² · r, the centrifugal force f
Becomes larger as it gets closer to the shaft surface, and as shown by the arrow in Fig. 3, a force acts on the lubricant in the direction of the shaft surface where there are dynamic pressure grooves, and the lubricating oil gradually moves in the dynamic pressure grooves 1a and 1b. To do. In this way, the lubricating oil can be replenished to the dynamic pressure grooves 1a and 1b without waste.

In the case of the above embodiment, the dynamic pressure generating grooves 1a, 1b, etc. may be formed on the rotary shaft 1 fitted between the sleeves 3 as shown in FIG. 4, or as shown in FIG. In addition, it is also possible to form only the curve-shaped groove 2 on the rotary shaft 1 ′ and form the dynamic pressure grooves 1 a and 1 b on the sleeve 3. Alternatively, one dynamic pressure groove may be formed in the rotary shaft 1 and the other dynamic pressure groove may be formed in the sleeve 3.

The material of the rotary shaft 1 and the sleeve 3 may be metal such as iron or aluminum alloy or resin, but especially when the rotary shaft 1 and the sleeve 3 are manufactured by injection molding the resin, the dynamic pressure groove is formed on the sleeve 3 side. This is rational because it can be formed simultaneously on the outer diameter surface of the shaft 1 and the inner diameter side of the sleeve 3 when forming. Further, the clearance 2 formed on the rotary shaft 1 may be formed in two or more places depending on the place where the dynamic pressure groove is formed.

[Effect of device]

Since the hydrodynamic bearing of the present invention has the structure described in detail above, most of the lubricating oil filled in the clearance formed on the rotary shaft can be effectively replenished. Also, the lubrication of the dynamic pressure bearing portion is good, the life is extended, and the long-term reliability of the bearing can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part of a rotary shaft of a hydrodynamic bearing of the present invention, FIG. 2 (a) is an improper modified embodiment, and FIG. 2 (b) is a preferred modified embodiment. FIG. 4 is a diagram showing the movement of the lubricating oil in the slack portion when the hydrodynamic bearing of the present invention is rotated, and FIGS. 4 and 5 are embodiments of the rotary shaft and sleeve of the hydrodynamic bearing of the present invention. Figure showing the combination of
6 and 7 are views showing a combination of a rotary shaft and a sleeve of a conventional hydrodynamic bearing. 1 …… Rotary shafts 1a, 1b …… Dynamic pressure groove 2 …… Nusumi 3 …… Sleeve

Claims (2)

(57) [Scope of utility model registration request] 1. A dynamic fluid having a dynamic pressure generating groove formed on a surface of a rotary shaft or an inner surface of a sleeve into which the rotary shaft is fitted, and a lubricating fluid filling screw is formed near the dynamic pressure generating groove. In the bearing, the smoothness is formed on the rotary shaft in a smooth curved shape, and is smooth from the curved bottom (the minimum position of the shaft diameter) to the vicinity of the dynamic pressure generating groove. A hydrodynamic bearing characterized in that 2. The hydrodynamic bearing according to claim 1, wherein the vicinity of the bottom of the slime is formed into a smooth curved shape, and a straight run up is made from the end of the curved portion near the bottom to the shaft surface.