JPS59113314A - Dynamic pressure type fluid bearing - Google Patents

Abstract

PURPOSE:To eliminate leakage of lubricant and improve reliability by forming, an introducing hole almost orthogonal to an axis along with a kerf and throttle parts provided in the periphery of said hole, in the middle part of herringbone type grooves provided on a shaft inserted in a bearing hole of a sleeve. CONSTITUTION:Three herringhone type grooves 11A, 11B, 11E are provided on a part of a bearing hole 12A allowing insertion of a shaft 11, in the captioned device, in which the shaft 11 is allwed to penetrate the bearing hole 12A of a sleeve 12 provided with a thrust receiving member 13 fixed to its lower end. An introducing hole 11D is provided between the grooves 11B and 11E, while cylindrical throttle parts 11G, 11H are provided above and below said hole 11D and a cylindrical kerf 11F is provided to communicate with said hole 11D. Furthermore, a throttle hole 11C is formed in the middle of the undersurface of the shaft 11 and put in communication with the introducing hole 11D. By constructing the captioned bearing as mentioned above, pressure distribution is formed as illustrated and not only rise of pressure between the lower end face 12B of the sleeve 12 and a thrust receiving member 13 can be averted but also leakage of lubricant can be prevented.

Description

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

Structure of the conventional example and its problems As the specific structure of the conventional hydrodynamic bearing device is shown in FIG. is rotatably inserted, the lower end surface 2B of the sleeve 2 is machined perpendicularly to the bearing hole 2A, and the thrust bearing member 3 is fixed thereto. The entire periphery of Group 1A and Group 1B is lubricated with oil or grease 14.

2C is a vent hole for opening the air between the two groups to the atmosphere and preventing this air from expanding at low pressure and pushing out the lubricant in group 2A to the outside. 2D is a flange.

In this conventional hydrodynamic bearing device, when the shaft and sleeve are rotated by a motor (not shown), etc.,
The pumping action of groups 1A and 1B generates oil film pressure and rotates without contact.

At this time, in the group 1A, Pla-Pl-Plb
In the group 2B, the pressure distribution becomes P2a-P2, and this generated pressure is also transmitted between the lower end surface of the shaft 1 and the thrust bearing member 3, resulting in pressures P3a, P2.
3b generates a force of 01 in the thrust direction, and the shaft 1 floats by 01 in the figure. Therefore, Group 1B is a hydrodynamic bearing that generates both radial and thrust forces. 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, the pressure increases during rotation at the joint between the lower end surface 2B of the sleeve 2B and the thrust receiver of the member 3 (pressure crab P=P2=P3), and lubricating oil leaks from the joint over time. There were times when the product ran out of oil and burned. In addition, when a conventional hydrodynamic bearing is used in a parked position, the lubricating oil discharged from the discharge hole 1D is in Group 1
The oil did not circulate toward B, but instead flowed out of the vent hole 2C, resulting in a serious problem of oil running out.

OBJECTS OF THE INVENTION In view of the above-mentioned 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 comprises a sleeve having a bearing hole, a shaft rotatably inserted into the bearing hole, and a thrust bearing fixed to the end surface of the sleeve and in contact with the lower end surface, is a herringbone type group, a lubricant introduction hole in the center of the group, a cut groove around the introduction hole, a constriction part without a group around the cut groove, and a part from the introduction hole to the lower end surface. By having a communicating oil supply hole in the center and disposing a lubricant around the herringbone type group, a highly reliable hydrodynamic bearing device with no lubricant leakage can be obtained.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to FIGS. 2 to 4. FIG. 2 is a cross-sectional view of the hydrodynamic bearing device according to the first embodiment of the present invention. In FIG. It has an end surface 12B and a ventilation hole 12C. Reference numeral 13 designates a thrust receiver, which is the same as the conventional example shown in FIG. Two herringbone-type groups 11A, 11B, and 11E are provided on the shaft 1, and an introduction hole 11D is provided between the groups 11B and 11E, and cylindrical constricted portions 11G, 11H are provided above and below the introduction hole 11D. A cylindrical cut groove 11F is provided continuous with the single-sided introduction hole. The lower surface of the shaft 11 is finished at a right angle, and a throttle hole 11C is drilled in the center, which commonly passes through the oil supply hole 11D. Lubricating oil 14 is applied to the vicinity of the group 11A, groups 11B and 11E.

The operation of the hydrodynamic bearing device configured as described above will be described below. First, the shaft 11 is still the sleeve 1.
2 is rotated by a motor (not shown), for example, when the shaft 11 rotates in the direction of arrow ω, the groups 11A,
The pumping action of 11B and 11C generates oil film pressure and rotates without contact. At this time, the pressure distribution of the group parts is P 6 a - P 6 in group 11A, respectively.
- like P 6 b, and in group 11B as P - a-P9a, and in group 11E as P7b-
It will look like P9b. 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.
Psb=P'yb, and the pressure at the introduction hole 11D is P=
P8a=P8b. In this way, 11G and 11H are
This is a bearing surface without groups around the kerf 11F, and has the effect of a pressure throttle to prevent a drop in pressure.

This pressure P passes through the oil supply hole 11E and is applied to the lower end surface of the shaft 11.
is propagated without a drop in pressure, and the pressure at the outlet of the oil supply hole 11E is P = P10a = P 1 as shown in Figure 2.
0 b4; P 8 a = P 8 b. This pressure generates a force of 02 in the thrust direction, and at this time C2
It stabilizes at a floating position (approximately 2 to 10 micrometers). At this time, as shown in FIG. 4, the thrust direction force Q2 is equal to the sum of the weight W1 of the rotating part and the thrust direction attraction force W2 generated when the rotor magnet 17 of the drive motor attracts the stator 18. It's about balance. 15 and 16 are rotary tables for fixing the disk.

Next, as shown in Fig. 3, a load of W3 is applied in the radial direction, and the shaft 11 is eccentric and the radial clearance becomes C4>05. In this case, the pumping action of the group with the smaller radial clearance causes The pressure increases, that is, as shown in FIG. 3, it becomes P7a) P7c, P7b) P7d, and the difference in these pressures generates a repulsive force in the radial direction opposing W3. At this time, the cylindrical constricted portions 11G 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 cases of Figure 2 and Figure 3, group 11E
The lubricant, which has been pressurized and transported, passes through the introduction hole 11D and the oil supply hole 11C and leaves the oil supply hole 11c under pressure (P 2 P 1
0 a = P 10 b ), the shaft 11B and the thrust receiver pass through the gap with the member 13 and circulate again toward the group 11E. Cylindrical kerf 11F
This is to ensure that the amount of circulating lubricant is sufficiently guided to the introduction hole 11D.

As described above, according to the present invention, the lower end surface of the sleeve 12 and the thrust receiver are connected to the lower end surface of the joint surface of the member 13 and the thrust receiver is connected to the pressure of the joint surface of the member 13 (P=Psb=P11a=pHb
) 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.

Furthermore, even when the hydrodynamic bearing device of the present invention is used in a parked position, the lubricant is retained in the group part by the surface tension of the lubricant itself, and does not flow out to the outside, resulting in high reliability. In this case, the lower end surface of the shaft and the thrust bearing are member 1.
Since there is no group in the bearing section between 3 and 3, even if a large external force is applied in the thrust direction while the bearing is stopped, it will not be affected by other grooved hydrodynamic bearings that have groups in the thrust direction bearing surface (not shown). In comparison, the hydrodynamic bearing of the present invention does not have a group on the bearing surface in the thrust direction (i.e., the thrust bearing consists of the member 13 and the lower end surface of the shaft 11). Even if a large external force is applied, there is no risk of damage to the bearing material due to the edges of the group, so if this hydrodynamic bearing device is used in a rotary drive device for a disk that records signals, for example, the excessive stress required when replacing the disk can be avoided. No failure occurs even under thrust force. The lower end surface 21B of the sleeve is still in the bearing hole 1.
It can be processed simultaneously with 2A to produce accurate squareness.

Since the thrust receiver 12B is fixed to this surface, the gap between the thrust receiver 12B 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. The shaft 21 is provided with 21B and 21E, and a cylindrical constriction portion 21G is provided between them, and the function of the cylindrical cut groove 11F of the shaft 21 is exposed to the counterbore groove 21F shown in Fig. 5, so that parts processing is possible. 021D is the introduction hole, 2
1C is an oil supply hole.

A third embodiment is shown in FIG.
G, and this constriction part 31G is the cylindrical constriction part 11 in FIG.
It has the same function as G and 11H. In the case of this third embodiment, the area of the herringbone type groups 31 B and 31 H can be increased, and the load capacity of the bearing can be increased. 31
G is an oil supply hole.

A fourth embodiment is shown in FIG. 7. In this case, a 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 kerf, 41C is an oil supply hole, and 41B and 41E are herringbone type groups.

FIG. 8 shows a fifth embodiment. In this case, an oil supply member 65 made of a porous material is attached to the lower surface of the shaft 61 so as to be connected to the oil supply hole 51C of the shaft 51. This eliminates the influence of variations in the diameter of the oil supply hole 51C on bearing performance. , stabilization of bearing performance is achieved ・51B, 61E
is a herringbone type group, 51F is a cylindrical kerf, 5
1D is an introduction hole, IG and 51H are a constriction part.

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 hess/gone type groups 11A, 11B, 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 substantially perpendicular to the axis, a cut groove around the groove, and a constriction part around the groove in the center of the herringbone type group provided on the shaft. 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 1 (a) is a cross-sectional view of a conventional hydrodynamic bearing device, Figures 1 (b) and (c) are illustrations of pressure distribution, and Figure 2
Figure (A) is a sectional view of a hydrodynamic bearing device according to an embodiment of the present invention, Figures 2 (B) and (C) are explanatory diagrams of pressure distribution, respectively, and Figure 3 (A) is a cross-sectional view of a hydrodynamic bearing device according to an embodiment of the present invention. Main part sectional view,
Figures 3 (b), (c), and 2) are explanatory diagrams of pressure distribution.
The figure is a sectional view of the hydrodynamic bearing, and Figure 5 is the second embodiment of the present invention.
Fig. 6 is a perspective view of the shaft of the third embodiment.
... Sleeve, 13 ... Thrust receiver is a member, 14 ... Lubricant, 11B, 11E ...
...Herringbone type group, 11C... Oil supply hole, 11D... Introduction hole, 11F...
Cut groove, 11G, 11H... Drawing part. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Fig. 2 Fig. 3 (in Fig. 7, 1.4ft., 17/r) 4fF IC evening 19 ri 1c da

Claims (1)

[Claims] A sleeve having a bearing hole, a shaft rotatably inserted into the bearing hole, and a thrust bearing fixed to the end surface of the sleeve and in contact with the lower end surface of the shaft are made up of members, and the shaft has a herringbone type group. , a lubricating oil introduction hole in the center of this herringbone type group, a cut groove provided around this introduction hole, a pressure constriction part with no group around this cut groove, and A hydrodynamic bearing device comprising: a lubricating hole communicating with the center of the lower end surface; and a lubricant disposed around the herringbone group.