JPS626158B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a hydrodynamic bearing device in which a groove provided on the outer periphery of a shaft serves as both a radial direction and a thrust direction bearing.

Structure of a conventional example and its problems As shown in FIG. 1, a conventional hydrodynamic bearing device has a sleeve 2 having a bearing hole 2A.
Groove 1 processed by etching etc.
A shaft 1 having A and 1B is rotatably inserted, a lower end surface 2B of the sleeve 2 is machined perpendicularly to the bearing hole 2A, and a thrust receiving member 3 is fixed thereto. A lubricant 4 such as oil or grease is applied around the grooves 1A and 1B. 2C is a vent hole for opening the air between the two grooves to the atmosphere and preventing this air from expanding at low pressure and pushing out the lubricant in the groove 2A to the outside. 2D is a flange.

In this conventional hydrodynamic bearing device, when the shaft or sleeve is rotated by a motor (not shown) or the like, an oil film pressure is generated by the pumping action of the grooves 1A, 1B, and the shaft or sleeve rotates without contact. At this time, in the 1A groove, P1a-P1
- P2 in grooves like P1b and 2B.
The pressure distribution becomes like a-P2, and this generated pressure is also transmitted between the lower end surface of the shaft 1 and the thrust receiving member 3, and the force Q1 is generated in the thrust direction by these pressures P3a and P3b, and the shaft 1 In the figure, only C1 floats up. Therefore, the groove 1B is a hydrodynamic bearing that generates forces in both radial and thrust directions. During rotation of the shaft 1, the lubricant 4 circulates through the throttle hole 1C and the discharge hole 1D provided in the shaft 1.
However, in the above configuration, pressure increases during rotation at the joint between the lower end surface 2B of the sleeve and the thrust receiving member 3 (pressure: P=P2=P
3) The lubricating oil leaked from the joint over time, causing oil depletion and seizing. Furthermore, when a conventional hydrodynamic bearing is used in a parked position, the lubricating oil discharged from the discharge hole 1D does not circulate toward the groove 1B, but flows out from the ventilation hole 2C, resulting in oil shortage. It had serious drawbacks.

OBJECTS OF THE INVENTION In view of the above drawbacks, the present invention provides a highly reliable hydrodynamic bearing device that can be used in both the radial and thrust directions without lubricant leakage and can be used even in a parked position.

Structure of the Invention The present invention includes a sleeve having a bearing hole, a shaft rotatably inserted into the bearing hole, and a thrust receiving member fixed to the end surface of the sleeve and in contact with the lower end surface, A herringbone groove, a lubricant introduction hole in the center of the groove, a cut groove around the introduction hole, a constriction part without a groove around the cut groove, and a lubricant introduction hole in the center of the lower end surface from the introduction hole. It has a communicating oil supply hole and a lubricant is disposed around the herringbone groove, thereby providing a highly reliable hydrodynamic bearing device with no lubricant leakage.

DESCRIPTION OF EMBODIMENTS Examples of the present invention will be described below with reference to FIGS. 2 to 4. FIG. 2 is a sectional view of a hydrodynamic bearing device according to a first embodiment of the present invention.
In FIG. 2, 11 is a shaft, and 12 is a sleeve, which has a bearing hole 12A, a lower end surface 12B perpendicular to the bearing hole, and a ventilation hole 12C. 13 is a thrust receiving member, which is the same as the conventional example shown in FIG. The shaft 1 is provided with two herringbone grooves 11A, 11B, and 11E.
An introduction hole 11D is provided between 1B and 11E, and cylindrical constricted portions 1G and 11H are provided above and below the introduction hole 11D.
Further, a cylindrical cut groove 11F is provided continuous to the introduction hole. The lower surface of the shaft 11 is finished at a right angle,
A throttle hole 11C is drilled in the center, and an oil supply hole 11D
I'm used to it. Groove 11A and Groove 11
Lubricating oil 14 is applied to the vicinity of B and 11E.

The operation of the hydrodynamic bearing device configured as described above will be described below. First, when the shaft 11 or the sleeve 12 is rotated by a motor (not shown) or the like, for example, when the shaft 11 rotates in the direction of the arrow ω, an oil film pressure is generated by the pumping action of the grooves 11A, 11B, and 11C, and the shaft 11 rotates without contact. At this time, the pressure distribution in the groove part is P6a-P6-P6b in groove 11A, respectively.
and in groove 11B P7a-P
9a, and P7b-P9b in groove 11E.
become that way. In addition, the pressure in the cylindrical constricted portions 11G and 11H hardly decreases because the bearing clearance is sufficiently small, and as shown in Fig. 2, P8a
≒P7a, P8b≒P7b, and the introduction hole 11D
The pressure at is P=P8a=P8b. In this way, 11G and 11H are bearing surfaces that do not have grooves around the kerf 11F, and have the effect of a pressure throttle to prevent a drop in pressure.

This pressure P is propagated to the lower end surface of the shaft 11 through the oil supply hole 11E with almost no pressure drop, and the pressure at the outlet of the oil supply hole 11E is P=P as shown in FIG.
10a=P10b≒P8a=P8b. This pressure generates a force Q2 in the thrust direction, and at this time it becomes stable at a position where it is floating only by C2 (approximately 2 to 10 micrometers). At this time, as shown in Fig. 4, the directional force Q2 of this thrust is the self-weight W of the rotating part
1 and the thrust direction attraction force W2 generated when the stator 18 is attracted by the rotor magnet 17 of the drive motor. 15 and 16 are rotary tables for fixing the disk.

Next, as shown in Fig. 3, a load W3 is applied in the radial direction, causing the shaft 11 to become eccentric, resulting in a radial clearance C4.
>C5, but in this case, the pressure due to the pumping action of the groove on the side with the smaller radial clearance increases, that is, as shown in Fig. 3, P7
a>P7c and P7b>P7d, and due to these pressure differences, a repulsive force in the radial direction opposing W3 is generated. At this time, the cylindrical constriction part 1
1G and 11H serve to prevent the pressure on the high pressure side (P7a, P7b) from escaping to the low pressure side (P7c, P7d). In both Figures 2 and 3,
The lubricant pressurized and conveyed by the groove 11E passes through the introduction hole 11D and the oil supply hole 11C to the oil supply hole 1.
It is discharged from 1c under pressure (P=P10a=P10b), passes through the gap between the shaft 11B and the thrust receiving member 13, and circulates again toward the groove 11E. The cylindrical groove 11F is provided to ensure a sufficient amount of the circulating lubricant to be introduced into the introduction hole 11D.

As described above, according to the present invention, the pressure (P=P9
b=P11a=P11b) is almost equal to atmospheric pressure, and there is no pressure difference with the outside air, so the lubricant does not flow out from this joint surface, so reliability is high. Further, even when the hydrodynamic bearing device of the present invention is used in a parked position, the lubricant is retained in the groove portion by the surface tension of the lubricant itself, and does not flow out to the outside, resulting in high reliability. Furthermore, in the present invention, since no groove is provided in the bearing portion between the lower end surface of the shaft and the thrust receiving member 13, even if a large external force is applied in the thrust direction while the shaft is stopped, the bearing in the thrust direction Compared to other hydrodynamic bearings with grooves in their surfaces, the hydrodynamic bearing of the present invention has a bearing surface in the thrust direction (i.e., a bearing surface consisting of the thrust receiving member 13 and the lower end surface of the shaft 11).
Since there is no groove in the bearing, there is no risk of damage to the bearing material due to the edges of the groove even if a large external force is applied in the thrust direction while stopped. When used in a rotary drive device, it will not fail even when subjected to excessive thrust force when replacing a disk. Further, the lower end surface 21B of the sleeve can be machined simultaneously with the bearing hole 12A to obtain an accurate squareness. Thrust receiver 1 on this surface
Since 2B is fixed, the gap between the shaft 11 and the lower end surface of the shaft 11 can be maintained with high accuracy, and a bearing with excellent stability can be obtained.

A second embodiment of the present invention will be described below with reference to FIG. 21B, 21E on the shaft 21
are provided, and a cylindrical constriction part 21G is provided between them.
Since the counterbore groove 21F shown in FIG. 5 performs the function of the cylindrical cut groove 11F of the shaft 21, it becomes easy to process the parts. 21D is an introduction hole, and 21C is an oil supply hole.

FIG. 6 shows a third embodiment. In this case the shaft 31
There is a substantially round constricted portion 31G around the counterbored hole 31F and the introduction hole 31D, and this constricted portion 31G performs the same function as the cylindrical constricted portions 11G and 11H shown in FIG. In the case of this third embodiment, the areas of the herringbone grooves 31B and 31E can be increased, and the load capacity of the bearing can be increased. 31C is an oil supply hole.

FIG. 7 shows a fourth embodiment. In this case, the cylindrical constriction part 41G is provided only above the introduction hole 41D of the shaft 41. In this case, the length in the axial direction is slightly shortened, and the bearing can be made smaller. 41F is a cylindrical groove, 41C is an oil supply hole, and 41B and 41E are herringbone grooves.

FIG. 8 shows a fifth embodiment. In this case the shaft 51
An oil supply member 55 made of a porous material is attached to the lower surface of the shaft 51 in series with the oil supply hole 51C.This eliminates the influence of variations in the diameter of the oil supply hole 51C on bearing performance, and improves bearing performance. stabilization is achieved. 51B, 51E are herringbone grooves, 51F is a cylindrical groove, 51D
is an introduction hole, and 51G and 51H are throttle parts.

In the first embodiment shown in FIG. 2, the cylindrical groove 11F may not be provided on the shaft 11, but may be provided on the inner surface of the bearing hole 12A of the sleeve 12, on the surface facing the introduction hole 11D.

In the first embodiment shown in FIG. 2, the herringbone grooves 11A, 11B, and 11E may be provided on the inner surface of the bearing hole 12A of the sleeve 12 instead of on the shaft 11.

Effects of the Invention As described above, the present invention provides an introduction hole approximately perpendicular to the axis in the center of the herringbone groove provided on the shaft, a kerf around the kerf, and a constriction around the groove. It is possible to obtain a highly reliable hydrodynamic bearing device without leakage of lubricating oil, and its practical effects are significant.

[Brief explanation of the drawing]

Figure 1A is a sectional view of a conventional hydrodynamic bearing device, Figure 1B and C are explanatory diagrams of pressure distribution, respectively.
FIG. 2A is a cross-sectional view of a hydrodynamic bearing device according to an embodiment of the present invention, FIG. 2B and C are explanatory diagrams of pressure distribution, respectively, FIG. Figures 3B, C, and D are explanatory diagrams of pressure distribution, Figure 4 is a sectional view of the same dynamic pressure type fluid bearing, Figure 5 is a perspective view of the shaft of the second embodiment of the present invention, and Figure 6 is the FIG. 7 is a perspective view of the shaft of the fourth embodiment, and FIG. 8 is a front sectional view of the shaft of the fifth embodiment. 11, 21, 31, 41, 51...axis, 12...
...Sleeve, 13...Thrust receiving member, 14...
...Lubricant, 11B, 11E... Herringbone groove, 11C... Oil supply hole, 11D... Introduction hole, 11F... Cut groove, 11G, 11H... Restricted portion.

Claims (1)

[Claims] 1 Consists of a sleeve having a bearing hole, a shaft rotatably inserted into the bearing hole, and a thrust receiving member fixed to the end surface of the sleeve and in contact with the lower end surface of the shaft, and the shaft has a herringbone groove. , a lubricating oil introduction hole in the center of this herringbone groove, a cut groove provided around this introduction hole, a pressure constriction part having no groove around this cut groove, and A hydrodynamic bearing device having a lubricating hole communicating with the center of the lower end surface, and having a lubricant arranged around the herringbone groove.