JPH01295020A - Bearing device - Google Patents

Abstract

PURPOSE:To eliminate the external part flow-out of the lubrication oil of an escape part and to prevent the breakdown of an instrument by the external part splash of the lubrication oil by forming the diameter of the place on which a vent hole is formed of the escape part of a sleeve smaller than those of both sides in the axial direction. CONSTITUTION:The diameter D1 of the place provided with the vent hole 26 to the external part of the escape part 25 provided between the radial bearing faces 22a, 22b apart in the axial direction of the inner diameter face of a sleeve 20 is formed smaller than the diameters D2 of the axial directions both sides. The damage of an instrument due to the splash of a lubrication oil can be prevented without the lubrication oil held at an escape part 25 by the centrifugal force by the rotation of the sleeve 20 being flowed out of a vent hole 26.

Description

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

[Conventional technology]

Among conventional bearing devices of this type, an example of a device used for an optical deflector is shown in FIG.

In this bearing device, one axial end of a shaft 10 is attached to a mounting base 1 by press fitting or the like, a sleeve 20 is rotatably fitted around the shaft 10, and is attached to the upper end of the sleeve 20. The lower end surfaces of the flat plate-shaped thrust receivers 2 and 3 face the upper end surface of the shaft body 10 in a plane.

The outer peripheral surface of the shaft body 10 is provided with cylindrical radial bearing surfaces 12a and 12b in which herringbone-shaped grooves 11a and llb for generating dynamic pressure are formed at two locations spaced apart in the axial direction. The radial receiving surfaces 12a and 12b are connected to the sleeve 2.
Cylindrical radial bearing surfaces 22a, 2 provided on the inner diameter surface of
A dynamic pressure type radial bearing is formed by opposing the bearing 2b with a radial clearance therebetween.

Further, the lower end surface (inner surface) of the thrust receiver 23 is provided with a planar thrust bearing surface 24 in which a spiral groove for generating dynamic pressure (not shown) is formed. A dynamic pressure type thrust bearing is configured to face a planar thrust bearing surface 14 provided on the upper end surface of the bearing.

A radial bearing surface 22 is provided on the inner diameter surface of the sleeve 20 at a location between two separate radial bearing surfaces 22a and 22b.
A relief portion 25 having a larger diameter than the sleeves a and 22b is provided, and the relief portion 25 is provided with a radial ventilation hole 26 communicating with the outer surface of the sleeve 20.

Further, on the axially upper inner diameter surface of the sleeve 20, at a location between the radial bearing surface 22a and the thrust bearing surface 24,
A relief portion 27 having a larger diameter than the radial bearing surface 22a is provided, and a radial ventilation hole 28 communicating with the outer surface of the sleeve 20 is provided in the relief portion 27.

The above radial bearing surfaces 22a, 22b and radial bearing surface 1
Bearing clearance between 2a and 12b, thrust bearing surface 24
The bearing clearance between and the thrust bearing surface 14 and the radial clearance between the relief portion 25, 27 and the shaft body 10 are filled with oil and grease, respectively.

A lubricant such as magnetic fluid is retained.

A polygon mirror 31 fitted to the sleeve 20 is attached to the upper surface of the flange 30 provided on the sleeve 20,
An annular rotor magnet 33 is attached to the lower surface of the flange 30 via a yoke 32, and balance rings 35 are fitted onto the sleeve 20 and disposed on the upper surface of the polygon mirror 31 and the lower surface of the yoke 32, respectively. 36 is tightened with bolts 37 to fix the polygon mirror 31 and rotor magnet 33 to the flange 30.

An annular stator coil 34 facing the rotor magnet 33 in the axial direction is attached to the mounting base l, and these rotor magnets 33 and the stator coil 3
4 constitutes a driving motor mechanism of the bearing device.

The bearing device having the above configuration is assembled in a sealed state in a housing (not shown), and when in use, the motor mechanism is driven to rotate the sleeve 20, and the laser beam incident from an external light source is reflected by the polygon mirror 31. The reflected laser light is then irradiated onto the photosensitive drum through a window provided in the housing.

Furthermore, the bearing device used for the hard disk has almost the same structure as the bearing device for the optical deflector, except that the disk is attached to a sleeve instead of the polygon mirror.

[Problem to be solved by the invention]

In the above-mentioned conventional bearing device, when the sleeve 20 is rotated, centrifugal force is applied to the lubricant of oil, grease, and Mi magnetic fluid held in the radial gap between the relief portion 25.27 and the shaft body lO. As a result, the lubricant flows out of the sleeve 20 through the ventilation holes 26 and 28 provided in the relief portions 25 and 27, and the lubricant becomes a mist in the internal space of the sealed housing. A phenomenon of scattering occurred.

For this reason, in a bearing device for an optical deflector, there is a problem in that the reflective surface becomes cloudy due to the lubricant adhering to the polygon mirror, reducing the reflectance of laser light.

In addition, in bearing devices for hard disks, the gap between the magnetic head and the disk is very narrow, so lubricant adhering to the disk comes into contact with the magnetic head and damages the magnetic head, resulting in a so-called head crash. There was a problem in that it caused the occurrence of

An object of the present invention is to solve the above problems and provide a bearing device in which the lubricant held in the relief part of the sleeve is less likely to flow out from the vent hole to the outside of the sleeve due to centrifugal force. do.

[Means to solve the problem]

In this invention, the inner diameter surface of the sleeve is larger than the cylindrical radial bearing surface provided at a plurality of locations separated in the axial direction and the radial bearing surface provided between the radial bearing surfaces at the plurality of locations. a large-diameter relief part, the relief part is provided with a ventilation hole that communicates with the outer surface of the sleeve, and the outer diameter surface of the shaft body fitted to the inner diameter surface of the sleeve is provided with a radial bearing surface of the sleeve. In a bearing device having a radial bearing surface provided opposite to the sleeve, the diameter of the relief portion of the sleeve is set to be smaller at the portion where the ventilation hole is provided than the diameter at the portions on both sides of the ventilation hole in the axial direction. It is.

Further, the present invention includes a sleeve having a thrust bearing attached to one axial end thereof and a shaft body fitted to an inner diameter surface of the sleeve, and a cylindrical radial bearing surface is provided on the inner diameter surface of the sleeve. , a thrust bearing surface is provided on the inner surface of the thrust receiver, a radial bearing surface facing the radial bearing surface of the sleeve is provided on the outer diameter surface of the shaft body, and a thrust bearing surface facing the thrust bearing surface of the thrust receiver is provided on the outer diameter surface of the shaft body. are respectively provided on one axial end surface, and a relief portion having a larger diameter than the radial bearing surface is provided on the inner diameter surface of the sleeve at a location between the radial bearing surface and the thrust bearing surface, and the relief portion is provided with a relief portion having a larger diameter than the radial bearing surface. In this bearing device, the diameter of the relief portion of the sleeve is set smaller than the diameter of the portion on both sides of the ventilation hole in the axial direction. It is.

[Effect]

In this invention, when the drive mechanism is driven to rotate the sleeve or shaft body, the lubricant held in the relief part is pressed against the inner diameter surface of both sides of the ventilation hole in the axial direction by centrifugal force, and the ventilation hole is closed. Since the lubricant is prevented from moving due to the difference in diameter between the sleeve and the sleeve, the lubricant is less likely to flow out of the sleeve via the ventilation hole.

〔Example〕

FIG. 1 shows an embodiment in which the present invention is applied to the bearing device shown in FIG. 3.

The relief portion 25 is provided at a location between the radial bearing surfaces 223 and 22b that are separated in the axial direction on the inner diameter surface of the sleeve 20.
The central portion where the ventilation hole 26 is provided and the portions on both sides in the axial direction are formed into cylindrical shapes with different diameters.
The diameter D2 is smaller than the diameter D2 at both sides of 6 in the axial direction.

Additionally, a relief portion 2 is provided between the radial bearing surface 22a and the thrust bearing surface 24 on the inner diameter surface of the sleeve 20.
7, the diameter of the location where the ventilation hole 28 is provided is,
It is smaller than the diameter D4 at both sides of the ventilation hole 28 in the axial direction.

However, ventilation holes 26.28 in each relief part 25.27
The diameters D+ and Ds of the portions provided cannot be equal to or smaller than the diameters of the radial bearing surfaces 22a and 22b of the sleeve 20. The reason is the ventilation hole 26.2
8 is also a part that constitutes the relief portion 25.27, so the diameter of the relief portion 25.27 is equal to the diameter of the radial bearing surface 22.
There is a principle in terms of bearing performance that the diameter must be larger than the diameters of a and 22b, and that the ventilation holes 26° and 28
The diameter DI, D3 at the location where is provided is the radial bearing surface 22a
, 22b, the sleeve 20 and the shaft lO cannot be assembled, and the diameter DIlD3 at the location where the ventilation hole 26.28 is provided is smaller than the diameter of the radial bearing surface 22a,
If the diameter is equal to that of sleeve 22b, the assembly is sometimes performed using sleeve 2.
When the shaft body 10 is fitted to the radial bearing surfaces 22a and 22b of 0, the lubricant such as oil and grease applied to the radial bearing surfaces 22a and 22b in advance adheres to the shaft body 10. is the relief part 25°27 ventilation hole 2
When the sleeve 20 rotates, the lubricant adhering to the shaft body 10 also adheres to the place where the ventilation hole 26.
This is because it will flow out from 28.

The configuration of each part other than the above is the same as that in FIG. 3, so the same reference numerals are given to the main parts, and repeated explanation will be omitted.

In the bearing device configured as described above, the sleeve 2
There are ventilation holes 26.28 on the inner diameter surface of the relief part 25.27 of 0.
At the boundary between the location where the ventilation holes 26 and 28 are provided and the locations on both sides of the ventilation holes 26 and 28 in the axial direction, there is a stepped surface having a height of 1/2 of the diameter difference (Dg D+) between the two in one relief part 25. , in the other relief part 27, the difference in diameter between the two (D, -D,)
A step surface having a height of 1/2 of the height of the height difference surface is formed respectively.

Therefore, when the sleeve 20 rotates, the relief portion 25.2
The lubricant No. 7 is held in a state pressed against the inner diameter surface on both sides of the ventilation hole 26 and 28 in the axial direction by centrifugal force, and the lubricant is prevented from moving by the stepped surfaces, so that the lubricant is not lubricated. The agent is less likely to flow out of the sleeve 20 via the vent holes 26,28.

FIG. 2 shows another embodiment of the bearing device of FIG. 1.

In this embodiment, the radial bearing surface 22a of the sleeve 20
, 22b has a cylindrical shape in the central part where the ventilation hole 26 is provided, but the parts on both sides of the central part in the axial direction have a diameter smaller than that of the central part. By forming it into a conical shape with a larger diameter on both end portions in the direction, the diameter of the portion where the ventilation hole 26 is provided is made smaller than the diameter of the portion on both sides of the ventilation hole 26 in the axial direction.

The relief portion 27 provided between the radial bearing surface 22a and the thrust bearing surface 24 of the sleeve 20 is not provided with a ventilation hole, and the radial bearing surface 2 is
A communication hole 29 is provided in the axial direction to communicate with the relief portion 25 between 2a and 22b.

Since the configuration of each part other than the above is the same as that in FIG. 3, the same reference numerals are given to the main parts, and repeated explanation will be omitted.

In this embodiment, when the sleeve 20 rotates, the lubricant held in the relief portion 27 between the radial bearing surface 22a and the thrust bearing surface 24 flows through the communication hole 29 between the radial bearing surfaces 22a and 22b. Even if the air flows out into the escape part 25, the diameter of the part where the ventilation hole 26 is provided in the escape part 25 is smaller than the diameter of the parts on both sides of the ventilation hole 26 in the axial direction. As in the embodiment shown in FIG. 1, the lubricant is prevented from moving to the location where the ventilation hole 26 is provided, and the lubricant is less likely to flow out of the sleeve 20 via the ventilation hole 26.

In each of the embodiments described above, the grooves lla and llb for generating dynamic pressure provided on the outer diameter surface of the shaft body 10 may be provided on the radial bearing surfaces 22a and 22b of the sleeve 20, and the grooves lla and llb for generating dynamic pressure provided on the outer diameter surface of the shaft body 10 may be provided on the radial bearing surfaces 22a and 22b of the sleeve 20, and the grooves lla and llb for generating dynamic pressure are provided on the outer diameter surface of the shaft body lO and the sleeve. It may be provided on both the inner diameter surface of 20. Further, the groove for generating dynamic pressure provided on the inner surface of the thrust receiver 23 may also be provided on the end surface of the shaft body 10, or may be provided on both the inner surface of the thrust receiver 23 and the end surface of the shaft body 10.

In addition, the radial bearing surfaces 22a and 22b and the radial bearing surface 1
2a and 12b may constitute a sliding bearing.

Furthermore, the thrust bearing surface 24 and the thrust bearing surface 14 may constitute a sliding bearing.

Further, the radial bearing surfaces 22a, 22b and the radial bearing surfaces 12a, 12b may be provided at three or more locations, and relief portions 25 may be provided at locations between the plurality of radial bearing surfaces 22a, 22b. may be provided at two or more locations.

Furthermore, if a magnetic fluid seal is attached to at least one of the lower end of the sleeve 20, that is, the open end, and the outer circumferential surface of the shaft body 1O facing the open end of the sleeve 20, the sleeve 2
Less lubricant scatters inside the 0.

Further, in each of the above embodiments, a sleeve 20 is provided around the shaft body 10.
However, the present invention can also be applied to a bearing device having a structure in which the shaft body rotates while being supported by a sleeve fixed to a mounting base.

In addition, in a bearing device in which the shaft body 10 is fixed, the shaft body l
Both axial ends of O may be fixed.

Note that the rotor magnet 33 and stator coil 34 constituting the drive motor mechanism of the bearing device may be cylindrical and opposed in the radial direction.

〔Effect of the invention〕

As explained above, according to the present invention, even if centrifugal force due to rotation acts on the lubricant held in the relief part of the sleeve, the lubricant flows out of the sleeve from the ventilation hole provided in the relief part. Things will go away. Therefore, in bearing devices for optical deflection transport, it is possible to prevent polygon mirrors from fogging up due to scattered lubricant, and in bearing devices for hard disks, it is possible to prevent damage to magnetic heads due to scattered lubricant. .

[Brief explanation of the drawing]

FIG. 1 is a longitudinal side view showing an embodiment of the present invention, FIG. 2 is a longitudinal side view showing another embodiment of the invention, and FIG. 3 is a longitudinal side view showing a conventional bearing device. In the figure, 10 is a shaft body, lla and Ilb are grooves for generating dynamic pressure, 12a and 12b are radial bearing surfaces, 14 is a thrust bearing surface, 20 is a sleeve, 22a and 22b are radial bearing surfaces,
23 is a thrust receiver, 24 is a thrust bearing surface, 25 is a relief part between the radial bearing surfaces, 26 is a ventilation hole in the relief part 25, and 27 is a relief part between the radial bearing surface and the thrust bearing surface. , 28 is the relief part 270 ventilation hole, D, ,D
. is the diameter of the part where the ventilation hole is provided on the inner diameter surface of the relief part, Dz,
Da is the diameter at both sides in the axial direction of the ventilation hole on the inner diameter surface of the relief portion. Patent applicant: NSK Ltd. Representative Patent attorney: Tetsuya Mori

Claims (2)

[Claims] (1) The inner diameter surface of the sleeve has a diameter larger than that of the cylindrical radial bearing surfaces provided at multiple locations separated in the axial direction and the radial bearing surfaces provided between the radial bearing surfaces at the multiple locations. a relief part, the relief part is provided with a ventilation hole communicating with the outer surface of the sleeve, and the outer diameter surface of the shaft body fitted to the inner diameter surface of the sleeve faces the radial bearing surface of the sleeve. In the bearing device having a radial bearing surface provided with a radial bearing surface, the relief portion of the sleeve is characterized in that the diameter of the part where the ventilation hole is provided is smaller than the diameter of the parts on both sides of the ventilation hole in the axial direction. Bearing device. (2) A sleeve having a thrust receiver attached to one axial end thereof, and a shaft body fitted to an inner diameter surface of the sleeve, and a cylindrical radial bearing surface is provided on the inner diameter surface of the sleeve. Thrust bearing surfaces are provided on the inner surfaces of the thrust receivers, and the shaft body has a radial bearing surface facing the radial bearing surface of the sleeve on the outer diameter surface, and a thrust bearing surface facing the thrust bearing surface of the thrust receiver on one side. are respectively provided on the axial end surfaces of the sleeves, and on the inner diameter surface of the sleeve,
In the bearing device, a relief portion having a larger diameter than the radial bearing surface is provided between the radial bearing surface and the thrust bearing surface, and the relief portion is provided with a ventilation hole communicating with the outer surface of the sleeve. A bearing device characterized in that the relief portion has a diameter smaller at a portion where the ventilation hole is provided than at portions on both sides of the ventilation hole in the axial direction.