JPH02199318A - Dynamic pressure bearing - Google Patents

Abstract

PURPOSE:To prevent abrasion powder from splashing outside and keep the high cleanliness of a driven body by organizing an earth with rolling elements which can be brought into contact with both of a housing and shaft directly or indirectly. CONSTITUTION:A dynamic pressure radial fluid bearing R and dynamic pressure thrust fluid bearing S are air bearings which are lubricated by the air existing in the respective bearing chinks. The center of the thrust receiving face 13 of the dynamic pressure thrust fluid bearing S is formed with a recess 15. In this recess 15 conductive balls 16 as rolling elements for an earth are arranged. Thus, abrasion powder is prevented from splashing outside, which can keep the high cleanliness of a driven body.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dynamic pressure bearing device having a groove for generating dynamic pressure between both members of a shaft and a housing, and particularly relates to a magnetic disk drive device 9 video tape. recorder.

The present invention relates to an improvement of a grounding device in a hydrodynamic bearing device suitable for use in rotating devices that require a high degree of cleanliness, such as drive devices for magneto-optical disks and optical disks.

[Conventional technology]

As an example of a grounding device in a conventional dynamic pressure bearing device, there is one shown in FIG. 5, for example. In this case, a cylindrical hole H is provided at the axis of the housing H, and a shaft J is fitted into the cylindrical hole H. This axis J and the cylindrical hole H3
A radial fluid bearing R and a thrust fluid bearing S having grooves for generating dynamic pressure are provided between the inner surface of the shaft and the inner surface of the shaft. The upper end of the shaft J is fixed to a rotating body K, and is rotatably supported by the rotating body on the housing H through a hydrodynamic bearing in a non-contact manner. A drive motor M is disposed inside the rotating body, and a magnetic disk D, which is a rotated body, is attached to the outer peripheral surface.

In order to prevent writing errors and reading errors from occurring on the magnetic disk D, a grounding stylus E at the tip of a leaf spring B of a grounding device E is pressed against the upper end surface of the shaft J.

[Problem to be solved by the invention]

However, in the conventional grounding device described above,
Because of the structure in which the grounding stylus E1 is pressed against the upper end surface of the shaft J by the leaf spring B, abrasion powder is generated on the upper end surface of the shaft J. The abrasion powder is removed from the magnetic disk D attached to the outer peripheral surface of the rotating body.
There is a problem in that the particles scatter and adhere to the surface of the disk, contaminating magnetic disk drives that require a high level of cleanliness.

Therefore, the present invention has been made by focusing on the above-mentioned conventional problems, and its purpose is to reduce the generation of wear particles, and even if wear particles are generated, they do not come out of the device. It is an object of the present invention to solve the above-mentioned conventional problems by providing a hydrodynamic bearing device equipped with a structured grounding device.

[Means to solve the problem]

In order to achieve the above object, a first aspect of the present invention provides that a cylindrical hole provided in a housing has a cylindrical radial bearing surface and eight thrust bearing surfaces, and a shaft that fits into the cylindrical hole is a radial bearing surface facing the radial bearing surface and a thrust bearing surface facing the thrust bearing surface; a groove for generating dynamic pressure is provided in at least one of the radial bearing surface and the radial bearing surface; In a hydrodynamic bearing device in which a groove for generating dynamic pressure is provided in at least one of a thrust bearing surface and a thrust bearing surface, a rolling element is disposed in a recess provided in one of the thrust bearing surfaces and a thrust bearing surface. .

In a second aspect of the present invention, the cylindrical hole provided in the housing has a cylindrical radial bearing surface and a thrust bearing surface, and the shaft that fits into the cylindrical hole faces the radial bearing surface. a radial bearing surface and a thrust bearing surface opposite to the thrust bearing surface, a spiral groove is provided in at least one of the radial bearing surface and the radial bearing surface, and the thrust bearing surface has a circulation communicating with the outer peripheral surface of the shaft. In a hydrodynamic bearing device having a hole, a rolling element having a diameter larger than the diameter of the opening of the circulation hole to the thrust bearing surface is disposed between the circulation hole and the thrust bearing surface.

Further, in a third aspect of the present invention, the cylindrical hole provided in the housing has a cylindrical radial bearing surface and a thrust bearing surface, and the shaft that fits into the cylindrical hole faces the radial bearing surface. a radial bearing surface and a thrust bearing surface opposite to the thrust bearing surface, a spiral groove is provided in at least one of the radial bearing surface and the radial bearing surface, and the thrust bearing surface has a circulation communicating with the outer peripheral surface of the shaft. In a hydrodynamic bearing device having a hole, rolling elements are disposed within the circulation hole.

Further, in a fourth aspect of the present invention, the cylindrical hole provided in the housing has a cylindrical radial bearing surface and a thrust bearing surface, and the shaft that fits into the cylindrical hole faces the radial bearing surface. In a hydrodynamic bearing device having a radial bearing surface and a thrust bearing surface opposite to the thrust bearing surface, and a groove for generating dynamic pressure is provided in at least one of the radial bearing surface and the radial bearing surface, one of the shafts. A rolling element was disposed on the base attached to the end of the housing so as to be able to come into contact with the housing.

[Effect]

While the hydrodynamic bearing device is rotating, the housing and the shaft fitted thereto via the hydrodynamic bearing are out of contact due to the dynamic pressure effect of the hydrodynamic bearing. However, since the ground is made up of rolling elements that are interposed between the housing and the shaft and can come into direct or indirect contact with both, the generation of wear particles is reduced, and
Grounding can be done inside the bearing device. As a result, abrasion powder is prevented from scattering to the outside, and the cleanliness of the driven body can be maintained at a required high level.

〔Example〕

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

1 and FIG. 2 shows a first embodiment of the present invention.

A sleeve 2 is formed by raising the axial center of a housing 1, which is a fixed member. The cylindrical hole 3 of the sleeve 2
The inner surface of the bearing is provided with cylindrical radial bearing surfaces 4.4 at three locations spaced apart in the axial direction. Further, a cylindrical thrust receiver 5 is fixed to the inner circumferential surface of the lower end of the sleeve 2 by means of a press-fit ring. The upper end surface of the thrust bearing 5 is a flat thrust bearing surface 6, on which a spiral groove 7 for generating dynamic pressure having a pattern as shown in FIG. 2 is formed.

A shaft 10, which is a rotating member, is inserted into the cylindrical hole 3 of the sleeve 2.
are mated. A radial bearing surface 11.1 is provided on the outer diameter surface of this shaft 10 at a position opposite to the radial bearing surface 4.4.
1 is provided. A herringbone-shaped groove 12 for generating dynamic pressure is formed in this to constitute a dynamic pressure radial fluid bearing R.

The lower end surface of the shaft 10 is a planar thrust bearing surface 13, which together with the thrust bearing surface 6 opposed thereto constitutes a dynamic pressure thrust fluid bearing S.

The dynamic pressure radial fluid bearing R and the dynamic pressure thrust fluid bearing S in this embodiment are air bearings that are lubricated by air existing in the respective bearing clearances.

A recess 15 is formed at the center of the thrust receiving surface 13 of the dynamic pressure thrust fluid bearing S, and a conductive ball 16 as a grounding rolling element is disposed within the recess 15. This ball 16 may be made of magnetic or non-magnetic material as long as it is conductive. The thrust bearing surface 6 on which the ball 16 rides is formed so that the center part thereof is slightly raised from the peripheral part. This moves the ball 16 from the center to the periphery,
It can be brought into reliable contact with the inner surface of the recess 15. However, even if the thrust bearing surface 6 is made flat and not necessarily inclined to a medium height, it is difficult to machine the surface to be completely perpendicular to the direction of gravity, but there is a certain probability that the ball 16 will fall inside the recess 15 of the shaft 10. contact with the sides.

The upper end of the shaft 10 is a cup-shaped hub (rotating body) 20
The shaft 10 is fixed to the bottom axis of the hub 20, so that the shaft 10
protrudes downward in the center.

A rotor 21 and a stator 22 that constitute a motor for driving rotation of the hub are installed inside the cup-shaped hub 20. The rotor 21 is fixed to the inner peripheral surface of the hub 2o, while
The stator 22 is fixed to the outer diameter surface of the sleeve 2.

Thus, the rotor 21 and the stator 22 are arranged to face each other in the radial direction with a slight gap between them.

A plurality of (two in the figure) magnetic disks D are attached to the outer diameter surface of the hub 20 via attachment members 23.

Note that this embodiment is a straight type in which the sleeve 2 is stationary and the shaft 10 rotates, and the recess 15 for storing the ball 6 is
A recess 15 is provided on the lower end surface of the shaft 1o, which serves as the thrust bearing surface 13, but in the case of an inverted type in which the shaft is stationary and the sleeve rotates, a recess 15 is provided on the thrust bearing surface 6 facing the shaft. Further, a recess may be provided in both the thrust bearing surface 6 and the thrust bearing surface 13.

Next, the action will be explained.

When the device is stopped, the hub 20 is lowered, and the thrust bearing surface 6 and thrust bearing surface 1 of the dynamic pressure thrust fluid bearing S are
3 are in contact with each other. Now, the stator 2 of the drive motor
When the coil No. 2 is energized, rotational force is generated in the rotor 21. As a result, the hub 20 and the magnetic disk D rotate together with the shaft 10.

With this rotation, the pressure of the air in the radial bearing clearance increases due to the pumping action of the herringbone-shaped dynamic pressure generating groove 12 formed on the radial bearing surface 11 of the shaft 10, and the shaft 10 is moved against the sleeve 2. They are supported in the radial direction in a non-contact manner.

At the same time, a spiral dynamic pressure generating groove 7 formed in the thrust bearing surface 6 of the thrust bearing 5 on the lower surface of the shaft 10
As a result, the pressure of the air within the thrust bearing clearance increases, and the shaft 10 and the knob 20 float in the axial direction and are supported.

Therefore, while the hub 20 is rotating, the housing 1 and the hub 2
Although the ball 16 and the ball 16 are not in contact with each other across the bearing gap, a grounding action is performed by the conductive ball 16 interposed between the two. That is, the ball 16 is placed on the upper surface of the thrust receiver 5 which is inclined to a middle height, so that it moves from the axial center position and reliably contacts the inner wall surface of the recess 15 on the lower surface of the shaft 10.

Therefore, electricity on the hub 20 side can be released to the housing l side via the ball 16.

This ball 16 is in contact with the hub 20 while rotating, and therefore generates far less abrasion powder than the conventional stylus-shaped earth. Moreover, since the hub 20 is grounded inside, it is possible to prevent wear particles from scattering to the outside of the hub 20.

Therefore, it is possible to prevent the magnetic disk D from being contaminated with abrasion particles and maintain a high degree of cleanliness.

FIG. 3 shows a second embodiment of the invention.

This embodiment is an example in which one of the hydrodynamic bearings is used as both a thrust bearing and a radial bearing.

That is, among the three upper and lower dynamic pressure generation grooves provided on the radial bearing surface 11 of the shaft 10, the lower one is a spiral dynamic pressure generation groove 25 that serves both as a thrust bearing and a radial bearing. . A through passage 26 that horizontally penetrates the shaft 10 is provided near the upper end of this dynamic pressure generating groove 25;
A circulation hole 28 consisting of a vertical passage 27 extending from this through passage 26 to the lower surface of the shaft 10 is provided.

The grounding ball 16 is disposed between the lower end of the circulation hole 28 and the thrust bearing surface 6, and has a diameter larger than the diameter of the opening of the circulation hole 28 to the thrust bearing surface 13. .

Now, when the hub 20 rotates, the air in the radial bearing clearance between the radial bearing surface 4 and the radial bearing surface 11 is moved between the thrust bearing surface 6 and the thrust bearing surface 13 by the pumping action of the groove 25 for generating dynamic pressure. The shaft 10 floats upward as it flows into the pressure chamber 40 on the outer periphery between. axis 1
When 0 floats up, the air in the pressure chamber 40 flows into the axial bearing gap through the vertical passage 27 and the horizontal passage 26 and circulates. As the shaft 10 rises, the ball 16 is released from its restraint and becomes movable. In this case, the gap between the ball 16 and the lower end of the circulation hole 28 is
Acts as a diaphragm for circulating air.

As a modification of this second embodiment, the diameter of the ball 16 may be made smaller than the diameter of the opening of the circulation hole 28 to the thrust receiving surface 13, so that the ball 16 enters the circulation hole 28. In this way, when the shaft 10 rotates, the ball 1
6 rolls into contact with both the upper end surface of the thrust receiver 5 and the inner wall surface of the circulation hole 28 to perform a grounding action. When the circulation hole 28 is stationary, the opening of the circulation hole 28 to the thrust bearing surface 13 and the thrust bearing surface 6 are in contact with each other, but when the shaft IO is rotating, the opening of the circulation hole 28 to the thrust bearing surface 13 and the thrust bearing surface are in contact with each other. 6 functions as a restriction for circulating air.

FIG. 4 shows a third embodiment of the invention.

This embodiment is an example of an inverted type in which the shaft is fixed and the housing is rotatable.

The shaft 10, which is a fixed member, is erected with its lower end fixed to a base 41. The sleeve 2 is provided to protrude downward from the axial center of the bottom surface of the housing l, which also serves as a hub, which is a rotating member, and the upper end side of the cylindrical hole 3 of the sleeve 20 is closed with a thrust receiver 5. Therefore, in this case, the thrust receiver 5
The lower surface of the thrust bearing surface 6 has a groove 7 for generating dynamic pressure.

The rotor 21 is fixed to the outer diameter surface of the sleeve 2. A stator 22 disposed radially opposite to the rotor 21 is fixed to an upright portion 30 formed on a base 41.

The upper surface 1a of the base 41 is formed into a slope with the inner side of the upright portion 30 slanting downward toward the center, and the grounding ball 16 is disposed on the slope. Therefore, the ball 16 disposed on the base 41 performs a grounding action while reliably rolling into contact with the outer diameter surface of the housing even while the hub 1 is rotating. That is, the ball 16 indirectly contacts the shaft 10 via the base 41.

In each of the above embodiments, a case has been described in which the grounding rolling element is a ball, but the rolling element is not limited to this, and the rolling element may be a roller or an ellipsoid.

Moreover, the number of the parts to be used is not limited to one, and two or more can be used.

The rolling elements may be electrically conductive, but in the case of a structure susceptible to the influence of the magnetic force of the rotor 21, for example, as in the third embodiment, it is preferable to use a non-magnetic material.

Furthermore, in each of the above embodiments, air is used as the working fluid of the hydrodynamic bearing;

It is also possible to use lubricants such as grease.

In addition, the groove 12.2 for generating dynamic pressure of the dynamic pressure radial fluid bearing R
5 is not the outer diameter surface of the shaft 10 (that is, the radial bearing surface 11) but the inner diameter surface of the sleeve 2 (that is, the radial bearing surface 4).
), or may be provided on both the outer diameter surface of the shaft 10 and the inner diameter surface of the sleeve 2.

Similarly, the groove 7 for generating dynamic pressure of the dynamic pressure thrust fluid bearing S is formed on the end surface of the thrust bearing 5 (i.e., the thrust bearing surface 6
), but may be provided on the end face of the shaft 10 (that is, the thrust receiving surface 13), or may be provided on both the end face of the thrust receiver 5 and the end face of the shaft 10.

〔Effect of the invention〕

As explained above, according to the present invention, in a hydrodynamic bearing device in which the housing and the shaft are not in contact with each other during rotation, the housing and the shaft are interposed between the housing and the shaft and can be in rolling contact with both directly or indirectly. The ground was made up of rolling elements. As a result, the generation of wear particles is reduced, and grounding can be established inside the bearing device.As a result, the scattering of wear particles to the outside is prevented, and a high level of cleanliness of the driven body can be maintained. is obtained.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of the first embodiment of the present invention, Fig. 2 is a plan view of the thrust bearing surface, Fig. 3 is a longitudinal sectional view of the second embodiment of the invention, and Fig. 4 is a longitudinal sectional view of the present invention. A vertical cross-sectional view of the third embodiment of the invention, and FIG. 5 is a vertical cross-sectional view of a conventional hydrodynamic bearing device. 1 is a housing, 3 is a cylindrical hole, 4 is a radial bearing surface,
6 is a thrust bearing surface, 7 is a groove for generating (thrust) dynamic pressure, 10 is a shaft, 11 is a radial bearing surface, 12 is a (radial)
A groove for generating dynamic pressure, 13 is a thrust receiving surface, work 5 is a recess, work 6 is a ball (rolling element), and 41 is a base.

Claims (4)

[Claims] (1) The cylindrical hole provided in the housing has a cylindrical radial bearing surface and a thrust bearing surface, and the shaft that fits into the cylindrical hole has a radial bearing surface and a thrust bearing surface opposite to the radial bearing surface. a groove for generating dynamic pressure is provided in at least one of the radial bearing surface and the radial bearing surface, and a groove for generating dynamic pressure is provided in at least one of the thrust bearing surface and the thrust bearing surface. What is claimed is: 1. A hydrodynamic bearing device provided with a groove, characterized in that a rolling element is disposed within a recess provided in at least one of the thrust bearing surface and the thrust bearing surface. (2) The cylindrical hole provided in the housing has a cylindrical radial bearing surface and a thrust bearing surface, and the shaft that fits into the cylindrical hole has a radial bearing surface and a thrust bearing surface opposite to the radial bearing surface. A hydrodynamic bearing device having opposing thrust bearing surfaces, a spiral groove provided in at least one of the radial bearing surfaces, and a circulation hole communicating with the outer peripheral surface of the shaft provided in the thrust bearing surface. A hydrodynamic bearing device according to claim 1, wherein a rolling element having a diameter larger than the diameter of an opening of the circulation hole to the thrust bearing surface is disposed between the circulation hole and the thrust bearing surface. (3) The cylindrical hole provided in the housing has a cylindrical radial bearing surface and a thrust bearing surface, and the shaft that fits into the cylindrical hole has a radial bearing surface and a thrust bearing surface opposite to the radial bearing surface. A hydrodynamic bearing device having opposing thrust bearing surfaces, a spiral groove provided in at least one of the radial bearing surfaces, and a circulation hole communicating with the outer peripheral surface of the shaft provided in the thrust bearing surface. A hydrodynamic bearing device, characterized in that a rolling element is disposed within the circulation hole. (4) The cylindrical hole provided in the housing has a cylindrical radial bearing surface and a thrust bearing surface, and the shaft that fits into the cylindrical hole has a radial bearing surface and a thrust bearing surface opposite to the radial bearing surface. In a hydrodynamic bearing device having thrust bearing surfaces facing each other and having a groove for generating dynamic pressure in at least one of the radial bearing surface and the radial bearing surface, the base is attached to one end of the shaft. A hydrodynamic bearing device characterized in that a rolling element is disposed inside the upper part so as to be able to come into contact with a housing.