JPH074428A - Bearing device - Google Patents

Abstract

PURPOSE:To secure the amount of lubricating oil by preventing lubricating oil from being splashed around at the thrust bearing section of a bearing device. CONSTITUTION:The fact that the structure of a thrust plate 13 is formed into a thrust bearing groove 131 in a spiral shape with a minute depth, is identical to that of a former one. In this case, in addition to that, a circular shaped groove 132 is formed while being adjacent to the outer side of the thrust bearing groove 131. The sufficient amount of lubricating oil can thereby be secured by preventing lubricating oil from flowing to the outside of the bearing with the aforesaid circular shaped groove made sufficiently deep.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device suitable for use in an external storage disk device of a computer or a precision instrument such as a VTR head which requires high rotational accuracy.

[0002]

2. Description of the Related Art In recent years, as a bearing device used in a spindle portion of a disk device or a VTR head, for the purpose of improving the rotation accuracy and reliability, or reducing the number of parts and the number of assembling steps, for example, as shown in FIG. Hydrodynamic bearings are used. FIG. 13 is a plan view showing the thrust bearing groove formed on the thrust plate. FIG. 12 shows an example in which a hydrodynamic bearing is applied to a disk device. The bearing device 1 has a bearing member (sleeve) 11 having a cylindrical hole, and a hub inserted into the sleeve 11 to hold the disk. 1a is mounted on the shaft body 12, and further a disc-shaped support plate (thrust plate) 13 and the like.

Herringbone-shaped radial bearing grooves 121 and 122 having a small groove depth are formed on the shaft body 12, and an appropriate lubricating fluid (lubricating oil) such as oil or grease is formed between the shaft body 12 and the inner surface of the cylindrical hole of the sleeve 11. ) A minute gap filled with 14a and 14b is formed. Further, as shown in FIG. 13, a thrust bearing groove 131 having a spiral shape and a minute depth is formed in the thrust plate 13, and is brought into contact with the end surface of the shaft body 12 through an appropriate lubricating oil 14c such as oil or grease. ing.

In such a structure, when the shaft body 12 rotates with respect to the sleeve 11 due to the electromagnetic force of the motor, the radial bearing grooves 121 and 122 are viscous pumping action.
Lubricating oil 14a, 14b to radial bearing grooves 121, 1
It operates so as to be pushed toward the folded portion of the herringbone pattern 22 and pressure is generated in the lubricating oil 14a, 14b. As a result, the shaft body 12 becomes the sleeve 11
In contrast, it is rotatably supported without contact and functions as a radial bearing.

Similarly, the thrust bearing groove 131 also has a shaft body 12.
Of the lubricating oil 14c causes the thrust bearing groove 13 to rotate.
Since it operates so as to be pushed into the center of No. 1, pressure is generated in the lubricating oil 14c, and the shaft 12 receives the upward force 16 and floats. At this time, if a downward force 15 is generated in the axial direction by a force external to the bearing so as to oppose the upward force 16, the shaft body 12 is thrust-supported in a non-contact manner.

[0006]

However, the above bearing device has the following problems. This point will be described below. FIG. 14 shows a part of the assembling process of the bearing device 1, and shows a process of incorporating the thrust plate 13 into the sleeve 11. At this time, for example, a necessary amount of lubricating oil 14c is dropped on the thrust plate 13 using a micro dispenser or the like, and the lubricating oil is filled in this assembly process.

However, when the bearing is operating, that is, the shaft 12
When the amount of oil required to form the floating clearance is dropped onto the thrust plate 13, the
In the state where the shaft body 12 is in contact with the thrust plate 13 as described above, a part of the oil is pushed out of the bearing like 14c2. When the shaft body 12 starts rotating, the pushed-out oil 14c2 does not return to the bearing portion because it scatters due to centrifugal force as shown in FIG. 16, resulting in an insufficient amount of oil.

In this case, the oil 14c remaining in the bearing portion
Since the gas-liquid interface of No. 1 is inside the outer circumference of the bearing, this thrust bearing has φDr smaller than the theoretical bearing diameter φDt.
Will function as a bearing. Therefore, the original bearing performance cannot be obtained, and problems such as insufficient bearing flying height or insufficient bearing rigidity occur, and the reliability of the bearing is impaired. Therefore, an object of the present invention is to make it possible to supply a necessary amount of lubricating oil to the bearing portion without scattering the oil.

[0009]

In order to solve such a problem, in the first invention, a shaft body having a bearing surface and a support plate having a supporting surface facing the bearing surface are provided. In a bearing device in which a bearing groove having a minute depth is formed on the support surface, and the bearing surface is supported in a non-contact manner with the support surface by dynamic pressure through a predetermined fluid, an outer peripheral portion adjacent to the bearing groove or At least one circumferential groove located in the inner peripheral portion and communicating with the bearing groove is provided on the bearing surface or the support surface.

According to a second aspect of the present invention, the shaft body has a bearing surface and a supporting plate having a supporting surface facing the bearing surface. The bearing surface or the supporting surface is formed with a bearing groove having a minute depth. ,
Also, in a bearing device in which the bearing surface is supported in a non-contact manner by a dynamic pressure through a predetermined fluid on the supporting surface, a circumferential groove positioned so as to cross the bearing groove is formed on the bearing surface or the supporting surface. The feature is that at least one is provided. In the first and second aspects of the invention, the circumferential groove may have a cross-sectional shape such that the depth gradually decreases toward the portion where the dynamic pressure supporting force is generated. it can.

[0011]

[Action]

(1) By providing at least one circumferential groove located on the outer peripheral portion adjacent to the bearing groove or the adjacent inner peripheral portion and communicating with the bearing groove on the bearing surface or the support surface, the bearing Supply the required amount of lubricating oil to the bearing during operation so that the dynamic thrust bearing performance as designed can be obtained. (2) By providing at least one circumferential groove that crosses the bearing groove on the bearing surface or the supporting surface, it functions as an oil seal to prevent oil from scattering and to improve the reliability of the bearing. So that sex can be secured over the long term. (3) The circumferential groove of (1) and (2) above has a cross-sectional shape in which the groove depth gradually decreases toward the portion where the dynamic pressure supporting force is generated. The oil is not allowed to remain in the groove portion and the lubricating oil can be smoothly supplied to the bearing groove portion to enable the original bearing operation.

[0012]

1 is a plan view showing an embodiment of the present invention. This shows the structure of the thrust plate 13 and is similar to the conventional one in that the thrust bearing groove 131 having a spiral shape and a minute depth is formed. However, in the present invention, in addition to this, the outside of the thrust bearing groove 131 is formed. Circumferential groove 1 adjacent to
32 is formed. The circumferential groove 132 is
For example, it is deeper than the bearing groove 131, and therefore has a sufficient groove capacity. Therefore, even if the shaft body 12 and the thrust plate 13 come into contact with each other as shown in FIG. 2 in the assembly process or the like, the oil is not pushed out of the bearing and is necessary for the thrust bearing in the circumferential groove 132. The amount of oil will be secured.

On the other hand, when the shaft body 12 floats during the operation of the bearing, a sufficient amount of oil is supplied from the circumferential groove 132 as shown in FIG. The problem that the bearing diameter becomes substantially smaller does not occur. Further, if the groove volume of the circumferential groove 132 has a sufficient margin with respect to the amount of oil required for the thrust bearing and the oil is filled a little more than the required amount, the filling amount can be strictly controlled. There is also an advantage that it is not necessary.

Although the circumferential groove is provided on the thrust plate in the above, it may be formed on the end face of the shaft body in the same manner as above. Further, as shown in FIG. 4, in the case of a spiral herringbone shape groove in which oil is pushed from both sides of the groove inner peripheral portion and the groove outer peripheral portion, as shown in the drawing, the lubricating oil is supplied from both inner and outer peripheral sides. It is necessary to form circumferential grooves 132B and 132A on both inner and outer peripheral sides of the bearing groove 131.

FIG. 5 is a plan view showing another embodiment of the present invention. This also shows the structure of the thrust plate 13, but is characterized in that the circumferential groove 132 is formed so as to cross the bearing groove 131. At this time, the bearing groove 13
1 is divided into an inner peripheral portion and an outer peripheral portion by a circumferential groove 132, and the groove section cross-section at that time is shown in FIG.

In FIG. 6, the inner peripheral portion of the bearing groove 131 corresponds to the C portion, which serves as a bearing that generates a dynamic pressure supporting force. Circumferential groove 1
Reference numeral 32 corresponds to the portion B, which plays the role of holding and supplying the lubricating oil as in the case of the first embodiment. On the other hand, bearing groove 1
The outer peripheral portion of 31 corresponds to the portion A in the figure, and oil 14c3 that separates from the lubricating oil 14c that constitutes the thrust bearing and tries to go out of the bearing is removed by the viscous pump action of the spiral groove. Acts to push back to 132. Therefore, this outer peripheral portion functions as an oil seal, and as a result, oil scattering can be prevented and long-term reliability can be ensured.

The thrust plate of FIGS. 1 and 5 also includes a third embodiment. That is, as shown in FIG. 7, the cross-sectional shape of the circumferential groove 132 is tapered so that it gradually becomes shallower toward the bearing groove portion 131, that is, the portion where the dynamic pressure supporting force is generated. As a result, when the shaft body 12 floats, the circumferential groove 132 moves to the bearing groove portion 1 due to a capillary phenomenon.
The lubricating oil 14c is smoothly supplied to 31. Therefore, it is possible to eliminate the problem that the oil remains in the circumferential groove portion 132, the supply to the bearing groove portion 131 is delayed, and the bearing operation is hindered.

Although the bearing device as shown in FIG. 12 has been described above, the present invention can be applied to the bearing device as shown in FIGS. 8 to 11. These will be briefly described below. In FIG. 8, a sleeve 21 having a cylindrical groove, a shaft body 22 inserted into the sleeve 21 and having a hub 2a for holding a disc mounted thereon, and a disk-shaped thrust plate 23 are provided. While forming the radial bearing grooves 221, 222, respectively,
A stepped portion is formed in the cylindrical hole of the sleeve 21 and the shaft body 22, and the cylindrical hole diameter of the sleeve 21 and the diameter of the shaft body 22 are made different at the radial bearing grooves 221, 222 to prevent loss of lubricating oil during assembly. This is to prevent mixing.

In FIG. 9, at least one of the bearing portions of the shaft body 32 is composed of a pair of groove patterns 322 which face each other in the directions of pushing the oil 34b.
The shaft diameter of each portion in which the pair of groove patterns 322 are formed,
Corresponding to this, the cylindrical hole diameter of the sleeve 31 is made different for each groove pattern and the oil 34b of a pair of groove pattern portions is made to communicate with each other, so that sufficient downward force can be secured and vibration or vibration can be ensured. This makes it difficult for malfunctions to occur due to impact and improves reliability.

In FIG. 10, the thrust downward force is obtained by combining, for example, asymmetrical helical bone groove patterns 42a and 42b in which the lubricating oil 44 communicates between the groove patterns. That is, the groove pattern 42a operates so as to push the lubricating oil 44 downward in the axial direction, and the groove pattern 42a acts so as to push the lubricating oil 44 upward in the axial direction, so that pressure is generated in the lubricating oil 44. At this time, as in the case of FIG. 9, since there is a difference in the shaft diameters of the groove patterns 42a and 42b, a thrust downward force is generated, and a sufficient downward force can be secured.

FIG. 11 is characterized in that the thrust downward force is obtained by the herringbone bearing groove 522 having a tapered shaft diameter. Since this tapered herringbone bearing groove 522 can be said to be a combination of two helical groove patterns whose groove angles are positive and negative, and which are continuously different, the same action and effect as in the case of FIGS. 9 and 10 are brought about. Will be done. As described above, it can be said that the present invention can be applied to general bearing devices that utilize thrust force.

[0022]

According to the present invention, the following effects can be expected. (1) If one or a plurality of circumferential grooves, which are located on the outer peripheral portion adjacent to the bearing groove or the adjacent inner peripheral portion and communicate with the bearing groove, are provided on the bearing surface or the support surface, The amount of lubricating oil required during the operation of the bearing can be supplied to the bearing portion, and the dynamic pressure thrust bearing performance as designed can be obtained. (2) If one or a plurality of circumferential grooves, which are located across the bearing groove, are provided on the bearing surface or the supporting surface, it functions as an oil seal and prevents the oil from scattering. Reliability can be ensured for a long time. (3) If the circumferential grooves of the above (1) and (2) are made to have a cross-sectional shape such that the groove depth gradually becomes shallower toward the portion where the dynamic pressure supporting force is generated, the circumferential groove will have a circular shape. Since the lubricating oil can be smoothly supplied to the bearing groove portion without leaving the oil in the groove portion, the original bearing operation can be performed.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a process drawing showing an assembly process of the bearing device according to FIG.

FIG. 3 is a cross-sectional view illustrating a state during operation of the bearing device according to FIG.

FIG. 4 is a plan view showing a modified example of FIG.

FIG. 5 is a plan view showing a second embodiment of the present invention.

6 is a sectional view showing a thrust plate groove portion shown in FIG.

FIG. 7 is a sectional view of a thrust plate groove portion for explaining a third embodiment of the present invention.

FIG. 8 is a cross-sectional view showing another example of the bearing device.

FIG. 9 is a cross-sectional view showing still another example of the bearing device.

FIG. 10 is a cross-sectional view showing another example of the bearing device.

FIG. 11 is a sectional view showing still another example of a bearing device.

FIG. 12 is a cross-sectional view showing a conventional example of a bearing device.

FIG. 13 is a plan view showing a thrust plate used in FIG.

FIG. 14 is a process diagram showing an assembling process of the conventional bearing device shown in FIG. 12 (before assembling the thrust plate).

FIG. 15 is a process diagram showing an assembling process of the conventional bearing device shown in FIG. 12 (after assembling the thrust plate).

16 is a cross-sectional view illustrating a state during operation of the bearing device shown in FIG.

[Explanation of symbols]

1, 2, 3, 4, 5 ... Bearing device, 1a, 2a, 3a ... Hub, 11, 21, 31, 41, 51 ... Bearing member (sleeve), 12, 22, 32, 42, 52 ... Shaft body, 13, 2
3, 33, 43, 53 ... Thrust plates, 14a, 14b,
14c, 24a, 24b, 24c, 34a, 34b, 3
5, 44, 54a, 54b ... Lubricating oil, 15 ... Upward force, 16 ... Downward force, 121, 122, 221, 222,
321, 322 ... Radial bearing groove, 131, 132A,
132B ... Thrust bearing groove.

Claims (3)

[Claims] 1. A shaft body having a bearing surface, and a support plate having a support surface facing the bearing surface, wherein the bearing surface or a bearing surface is formed with a bearing groove having a very small depth. In a bearing device in which a bearing surface is supported by a predetermined fluid in a non-contact manner by a dynamic pressure, in a circumferential shape that is located in an outer peripheral portion or an inner peripheral portion adjacent to the bearing groove and communicates with the bearing groove. At least one groove is provided on the bearing surface or the support surface. 2. A shaft body having a bearing surface, and a support plate having a support surface facing the bearing surface, wherein the bearing surface or a bearing surface is formed with a bearing groove having a minute depth. In a bearing device in which a bearing surface is supported in a non-contact manner by a dynamic fluid through a predetermined fluid, at least one circumferential groove positioned so as to cross the bearing groove is provided on the bearing surface or the support surface. A bearing device provided. 3. The circular groove has a cross-sectional shape such that the depth becomes gradually shallower toward a portion where a dynamic pressure supporting force is generated. Bearing device according to.