JPS63145816A - Dynamic pressure type fluid bearing device - Google Patents

Abstract

PURPOSE:To facilitate machining a dynamic pressure type thrust bearing by setting the thrust load supported by a thrust fluid bearing only in one direction to provide only one dynamic pressure type thrust bearing. CONSTITUTION:A disc 40 is disposed opposite to a sleeve 11 in such a manner as to be suitably spaced therefrom in the axial direction, and attraction type permanent magnets 50, 51 are fixed to the opposite axial sides 46, 16 of both. A flange portion 21 is attracted to an annular member 12 by the attraction force of the permanent magnet 50 mounted on the disc for the permanent magnet 51 and by the weight of a shaft 20. Accordingly the attraction force produced by the permanent magnets 50, 51 works to attract the shaft 20 in the axial direction to the annular member side of a housing through the disc 40, whereby the thrust load only in one direction is supported, so that a thrust bearing can be easily machined.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydrodynamic bearing device used in video tape recorders, digital audio tape recorders, compact disks, floppy disks, and the like.

[Conventional technology]

Traditionally, hydrodynamic bearings have been used in small rotating equipment such as video tape recorders (VTRs), digital audio tape recorders (DATs), and Fronby discs, which require high-speed and high-precision rotation performance. It is desired to do so.

As this type of bearing device, for example, Japanese Patent Application Laid-Open No. 61177
A structure described in Publication No. 14 is known, in which a groove for generating dynamic pressure is formed on the outer circumferential surface (radial surface) of the shaft that penetrates the housing, and the groove is formed on the inner circumferential surface (radial bearing surface) of the housing. A radial bearing that supports a radial load is constructed between the shaft body and the flange-shaped disc formed integrally with the shaft body, and the side surfaces of the flange-shaped disk formed integrally with the shaft body are attached to the periphery provided on the inner peripheral surface of the housing. The disks are housed in the circumferential groove so as to face each other, and grooves for generating dynamic pressure are formed on both sides of the disk (thrust surface), and grooves for generating dynamic pressure are formed on both sides of the circumferential groove (thrust bearing surface).
A thrust bearing that supports an axial load in the opposite direction is constructed between the two.

[Problem that the invention seeks to solve]

In the conventional hydrodynamic bearing device as described above, both sides of the disk integrated with the shaft body constitute thrust bearings, so there are two dynamic pressure type thrust bearings, so when using the bearing, There are disadvantages in that the torque increases and machining of the pair of thrust bearings is difficult.Also, since the shaft body is not restrained from moving in the axial direction, it will not be able to handle external forces during transportation, etc. when shipping the device. However, there is a drawback in that the shaft body causes axial vibration and radial rocking relative to the housing, damaging the thrust bearing and the radial bearing.

An object of the present invention is to eliminate the above-mentioned drawbacks and provide a hydrodynamic bearing device that has low torque and is equipped with a mechanism that prevents vibration and rocking of the shaft during transportation. do.

[Means for Solving the Problems] The hydrodynamic bearing device of the present invention has a shaft body in an inner circumferential groove provided between a sleeve and an annular member attached to one axial end of the sleeve. The flange is accommodated, the surface of the annular member facing the flange is a thrust bearing surface, and the surface of the flange facing the annular member is a thrust surface, and dynamic pressure is generated on at least one of the thrust bearing surface and the thrust surface. A unidirectional thrust fluid bearing is constructed by providing a unidirectional thrust fluid bearing.

Further, on the axial side surface of the housing opposite to the annular member, an attraction type permanent magnet is attached to at least one of the axial side surfaces of the disk attached to the shaft body, with the axial side surfaces of the disks facing each other. There is.

[Effect]

In the hydrodynamic bearing device of the present invention, the attraction force by the permanent magnet acts between the axial side surface of the housing opposite to the annular member and the axial side surface of the disk facing this, so that the axial The body is drawn toward the annular member of the housing in the axial direction via the disk, and a thrust load in only one direction is supported by a thrust fluid bearing constituted by the flange of the shaft and the annular member.

In addition, when transporting the bearing device, the flange of the shaft is held in close contact with the annular member of the housing by the attractive force of the permanent magnet, so even if external force is applied, the shaft remains against the housing. There is no axial vibration or radial rocking.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment in which the present invention is applied to a rotating section of a video tape recorder.

In the figure, reference numeral 9 denotes a lower drum, a sleeve 11 is coaxially fixed to the lower drum 9, and one shaft end of the sleeve 11 has an inner circumferential surface with a smaller diameter than the inner diameter of the sleeve 11. The annular member 12 is fitted and fixed. A housing 10 is constituted by the sleeve 11 and the annular member 12. The inner peripheral surface of the sleeve 11 has cylindrical radial bearing surfaces 13 and 1 on both sides in the axial direction, respectively.
4, and the radial bearing surface 1. A circumferential groove 15 communicating with the air vent hole 15a is formed between the sleeve 11 and the annular member 12, and a radial bearing surface 13 is formed between the sleeve 11 and the annular member 12.
．． An inner circumferential groove 17 whose bottom diameter is larger than that of groove 14 is provided.

A shaft body 20 is disposed to penetrate inside the sleeve 11 described above. The shaft body 20 is provided with a flange portion 21, and this flange portion 21 is accommodated in the inner circumferential groove 17 of the housing so that the axially outer side surface of the flange portion 21 faces the annular member 12. A lower end portion 20a having a smaller diameter axially outer than the flange portion 21 passes through the annular member 12 and extends outward from one axial end portion of the sleeve 11;
Further, the shaft body 20 has an upper end 20b opposite to the lower end 20a.
extends outward from the other shaft end of the sleeve 11.

The outer peripheral surface of the shaft body 20 is the radial bearing surface 1 of the sleeve 11.
3.14 are the radial surfaces 23.24, and the radial surfaces 23.24 are each formed with herring-pond grooves 25° 26 for generating dynamic pressure, and the shaft body 20 and the sleeve 11 are connected to each other. A dynamic pressure type radial fluid shaft body is constructed with oil, grease, air, etc. in between.

The axially inner side surface of the annular member 12 facing the flange portion 21 of the shaft body 20 is a planar thrust bearing surface 12a, and this thrust bearing surface 12a has a herringbone-shaped dynamic surface as shown in FIG. A groove 29 for generating pressure is formed,
A dynamic pressure type thrust fluid bearing is formed between the flange portion 21 of the shaft body 20 and the annular member 12 via oil, grease, air, etc.

A pedestal 31 to which a ring-shaped rotor 30 of a drive motor is attached is fixed to the lower end 20a of the shaft 20. This rotor 30 is radially opposed to a ring-shaped stator 33 attached to the lower drum 9.

Further, a disk 40 is integrally fixed to the upper end side portion 20b of the shaft body 20 by press fitting, shrink fitting, or the like. The disk 40 faces the sleeve 11 of the housing 10 with an appropriate gap in the axial direction, and the axial side surfaces 4 of the two facing each other.
At 6.16, an attraction type permanent magnet 50.51 is attached by adhesive or the like, and the attraction force of the permanent magnet 50 on the disk side to the permanent magnet 51 on the housing side and the rotor pedestal 31 are
The flange portion 21 of the shaft 20 is attracted to the annular member 12 by the weight of the shaft 20 with the disk 40 attached thereto. An annular intermediate member 41 is attached to the disk 40, and an upper drum 42 is attached to this intermediate member 41.

In the hydrodynamic bearing device having the above configuration, when the shaft body 20 rotates in a counterclockwise direction when viewed from above in FIG. A fluid film is formed in the radial bearing gap between them by the pumping action of the grooves 25 and 26 for generating dynamic pressure, and the radial load of the shaft body 20 is supported.

Further, a fluid film is formed in the thrust bearing gap between the thrust surface 21a of the flange portion 21 of the shaft body 20 and the thrust bearing surface 12a of the annular member 12 due to the pumping action of the groove 29 for generating dynamic pressure, and the shaft The body 20 is a permanent magnet 50.
51 and the weight of the shaft body 20, the disk 40, and the rotor pedestal 31, and the downward thrust load of the shaft body 20 in the axial direction is supported.

In the case of usage conditions in which a load exceeding the weight of the shaft body 20, disk 40, and rotor pedestal 31 acts as an upward thrust load in the axial direction, a permanent magnet 50.51 having an attraction force greater than these loads is used. By using this, it is possible to maintain the anti-thrust surface of the flange portion 21 of the shaft body 20 and the axially inner surface of the inner circumferential groove 17 of the sleeve 11 opposing thereto in a non-contact state.

When the hydrodynamic bearing device described above is not in use, the flange portion 21 of the shaft body 20 remains attracted to the annular member 12 by the attractive force of the permanent magnets 50 and 51, so that it is not subjected to external force. Even if the shaft body 20 does not vibrate in the axial direction or slide in the radial direction inside the sleeve 11,
It can always remain stationary.

In addition, in this embodiment, since the inner circumferential surface of the annular member 12 is formed to have a smaller diameter than the radial bearing surface 13.14 of the sleeve 11, if the outer diameter of the flange portion 21 of the shaft body 20 is formed smaller, However, a large area of the thrust bearing surface 12a can be ensured, and a thrust fluid bearing having a large load capacity can be constructed. Therefore, by making the outer diameter of the flange portion 21 smaller, the material costs for the shaft body 20 and sleeve 11 can be reduced, and by making the diameter of the thrust bearing portion smaller, the entire device can be made smaller.

In the above embodiment, the groove for generating dynamic pressure was provided on the radial surface of the shaft body. However, the groove for generating dynamic pressure may also be provided on the radial bearing surface of the sleeve, or the groove for generating dynamic pressure may be provided on the radial surface of the shaft. It may be provided on both the radial bearing surface and the radial bearing surface.

Furthermore, the groove for generating dynamic pressure provided on the thrust bearing surface of the annular member may be provided on the thrust surface of the flange portion, or may be provided on both the thrust surface and the thrust bearing surface.

In addition, regarding the permanent magnets provided on the opposing sides of the disk and sleeve in the axial direction, if one or both of the disk and sleeve is made of magnetic material, one of the permanent magnets may be omitted. can.

The hydrodynamic bearing device of the present invention can also be used as a device that rotates the housing with the shaft body fixed, and can be used not only as a navy blue shape as shown in Fig. 1 but also as an inverted vertical shape. It can also be used as a horizontal device.

Alternatively, the disk 40 and the intermediate member 41 may be integrated into one body instead of being made separately.
It may also be set to 0.

Although FIG. 3 is a reference example, an annular member 12 having an inner circumferential surface smaller in diameter than the inner diameter of the sleeve 11 is fitted and fixed to the other shaft end of the sleeve 11. A housing 10 is constituted by the sleeve 11 and the annular member 12. Further, an inner circumferential groove 17 is provided between the sleeve 11 and the annular member 12, the bottom of which has a larger diameter than the radial bearing surface 13.14. The shaft body 20 is provided with a flange portion 21, and this flange portion 21 is accommodated in the inner circumferential groove 17 of the housing so that the axially outer side surface of the flange portion 21 faces the annular member 12. Flange part 21
The small-diameter upper end 20b axially outer than the annular member 12
The lower end 20a of the shaft body 20, which is opposite to the upper end 20b, extends further outward than the one shaft end of the sleeve 11. ing.

The axially inner side surface of the annular member 12 facing the flange portion 21 of the shaft body 20 is a planar thrust bearing surface 12a, and this thrust bearing surface 12a has a herringbone-shaped groove 29 for generating dynamic pressure. A dynamic pressure type thrust fluid bearing is formed between the flange portion 21 of the shaft body 20 and the annular member 12 via oil, grease, air, etc.

Further, a disk 40 is integrally fixed to the upper end side portion 20b of the shaft body 20 by press fitting, shrink fitting, or the like. The disk 40 faces the sleeve 11 of the housing 10 with an appropriate gap in the axial direction, and the axial side surfaces 4 of the two facing each other.
At 6.16, a repulsive permanent magnet 50.51 is attached by adhesive or the like to attract the flange portion 21 of the shaft body 20 to the annular member 12.

Note that the other parts of the illustrated reference example are constructed in substantially the same manner as the first embodiment, and this reference example has substantially the same effects as the first embodiment.

Note that a groove for generating dynamic pressure may be provided on at least one of the thrust bearing surface 12a and the thrust surface 21a, and a groove for generating dynamic pressure may be provided on at least one of the radial bearing surface 13.14 and the radial surface 23.24. may be provided.

It can also be used horizontally or inverted.

〔Effect of the invention〕

As explained above, in the hydrodynamic bearing device of the present invention, the flange portion of the shaft passing through the housing is housed in the inner circumferential groove of the housing, and the annular member is fixed to the rod at one axial end of the sleeve. A dynamic pressure type thrust fluid bearing is constructed by providing a groove for generating dynamic pressure in at least one of the thrust surface of the flange facing the annular member and the thrust bearing surface of the annular member facing the flange. , with the axial side of the housing opposite the annular member facing the axial side of a disk attached to one axial end side of the shaft, and a suction-type permanent inlet on at least one of these axial sides. Since the structure is equipped with a magnet, the flange of the shaft body is drawn toward the annular member of the housing by the attractive force of the permanent magnet, and an axial thrust load is applied from the disk side to the annular member side. . Therefore, according to the present invention, since the thrust load supported by the thrust fluid bearing is only in one direction, there is only one dynamic pressure type thrust bearing, the processing of the dynamic pressure type thrust bearing is easy, and the bearing The torque during use is reduced, making it possible to use the bearing as the most suitable bearing for devices that require high-precision rotational performance.

Further, according to the present invention, the flange portion of the shaft body and the annular member of the housing are attracted by the attractive force of the permanent magnet, so that even if external force is applied during transportation of the device, the shaft body remains axially relative to the housing. Since directional vibration and radial rocking are less likely to occur, a hydrodynamic bearing device that does not damage the thrust bearing and the radial bearing can be obtained.

Furthermore, in the case of shaft rotation, the load applied from the disk to the flange is supported by a dynamic pressure type thrust fluid bearing, but if a load smaller than the attraction force of the permanent magnet is applied from the flange to the disk, Since the load applied to the dynamic pressure type thrust fluid bearing is reduced, it has the effect of being able to support a load smaller than the attractive force of the permanent magnet applied from the flange toward the disk.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, FIG. 2 is a plan view showing a thrust bearing surface of an annular member, and FIG. 3 is a NUr surface view of a reference example. In the figure, 10 is a housing, 11 is a sleeve, 12 is an annular member, 122 is an axial side surface (thrust bearing surface) of the annular member, 13.14 is a radial bearing surface, 16 is an axial side surface of the sleeve, and 17 is an inner periphery. Groove, 20 is the shaft body, 21 is the flange part, 21a is the axial side surface (thrust surface L) of the flange part.
23.24 is a radial surface, 25.26 is a groove for generating dynamic pressure on the radial surface, 29 is a groove for generating dynamic pressure on the thrust bearing surface, 40 is a disk, 46 is an axial side surface of the disk,
50.51 is a permanent magnet. Figure 1 Figure 2

Claims (2)

[Claims] (1) The housing has a sleeve and an annular member attached to one end of the sleeve in the axial direction, and a shaft body with a disk fixed to one shaft end is passed through the inner circumference of the housing. The axial side surface of the disk faces the side surface of the housing opposite to the annular member, and the inner circumferential groove provided between the sleeve and the annular member accommodates the flange portion provided on the shaft body, and the axial direction of the flange portion The side surface faces the axial side surface of the annular member, and the shaft body and the housing are connected by a groove for generating dynamic pressure provided on at least one of the radial surface provided on the outer circumferential surface of the shaft body and the radial bearing surface of the housing facing this. In a hydrodynamic bearing device comprising a radial fluid bearing between the housing and the housing, an attractive permanent magnet is attached to at least one of the axial side surface of the disk facing the housing and the axial side surface of the housing facing the disk. A groove for generating dynamic pressure is provided in at least one of the axial side surface of the flange facing the annular member and the axial side surface of the annular member facing the flange, and a thrust is generated between the flange and the annular member. A hydrodynamic bearing device comprising a hydrodynamic bearing. (2) The hydrodynamic bearing device according to claim 1, wherein the inner peripheral surface of the annular member has a smaller diameter than the radial bearing surface.