KR19980034760A - Hydrostatic Fluid Bearings - Google Patents

Abstract

The present invention is to increase the area of the peak pressure generating portion of the rotating shaft, the rotating shaft support member (sleeve), the rotary shaft is press-fit fixed to the dynamic pressure fluid bearing device to prevent the fluid pressure is concentrated on a part to improve the rotational stability of the rotating shaft A support member having a bushing portion formed on an inner circumferential surface thereof, a rotating shaft having a dynamic pressure generating groove formed on one side of the bushing portion and a rotating shaft, and a bearing bracket for supporting the supporting member and the rotating shaft. In the pressure fluid bearing apparatus, the dynamic pressure generating groove has a predetermined length in the axial direction of the rotating shaft, and a plurality of first grooves arranged at regular intervals on the circumference of the rotating shaft, and both ends of the first groove and the predetermined groove. It is formed by the second and third grooves which are connected to a predetermined length at an obtuse angle and are formed by the fluid flowing from the second and third grooves. The fluid pressure generated is characterized in that a fluid pressure of a predetermined size in the first groove.

Description

Hydrostatic Fluid Bearings

The present invention relates to a hydrostatic fluid bearing device, and more particularly, to increase the area of the peak pressure generating portion of the rotating shaft, the rotating shaft support member (sleeve), the rotation body is press-fit fixed to prevent the fluid pressure from being concentrated on a part The present invention relates to a dynamic pressure fluid bearing device having improved rotational stability of a rotating shaft.

Recently, as is well known, the head drive device of a video tape recorder, the scanner motor which is a polygon mirror drive device of a laser printer, the camcorder drive motor, etc. are gradually increasing in size and miniaturization. Such drive devices are precise and stable. Since hydrodynamic bearings are used because they require a bearing that can rotate at a very high speed, such hydrodynamic bearings have a spiral dynamic pressure generating groove and a herringbone shape to minimize frictional forces that hinder the rotation of the rotating shaft. Various shapes of dynamic pressure generating grooves such as grooves have been developed.

Referring to the accompanying drawings, a polygon mirror driving device of a laser printer using such a hydrostatic fluid bearing device as an example is as follows.

On the inner side of the sleeve 20 to which the rotary shaft 30 is fitted, a bushing portion 25 supporting the rotary shaft 30 is formed, and the rotary shaft 30 or the bushing portion 25 facing the bushing portion 25 is formed. On one side of the one side is formed a herringbone-shaped first dynamic pressure generating groove 35 for generating a fluid pressure for contactless rotation of the bushing portion 25 and the rotating shaft 30, the bushing portion 25 and the first The dynamic pressure generating groove 35 is formed.

FIG. 2 is an exploded view illustrating the rotation shaft 30 of FIG. 1, wherein the first dynamic pressure generating groove 35 may be formed on either side of the rotation shaft 30 or the bushing part 25, but may be formed on the rotation shaft 30. If the first dynamic pressure generating groove 35 is formed as an example, a plurality of herringbone-shaped first dynamic pressure generating grooves 35 are formed at equal intervals in the rotating shaft portion corresponding to the bushing portion 25. The groove area and the number of the first dynamic pressure generating grooves are determined according to the weight and load applied to the rotating shaft 30.

In addition, the first dynamic pressure generating groove 35 is formed by a turning etching process and a CVD deposition process, and the first groove and the second groove ( While 45 is an acute angle (β = 30 °), the two acute angles are connected to form a bent portion 60, and the first grooves 40 and the second grooves 45 are symmetric with respect to F.

On the other hand, the thrust bearing 50 in which the herringbone and the spiral-shaped second dynamic pressure generating groove 50a are formed to support the thrust load of the rotary shaft 30 and to raise the rotary shaft 30, One end portion is supported, and the rotation shaft 30 has a hub 70 press-fitted to rotate the rotation shaft 30 at a predetermined revolutions per minute, and the hub 70 has only a portion of the motor 60 and the laser beam shown therein. The polygon mirror 80 which reflects this to a photosensitive drum is provided.

Referring to the polygon mirror driving apparatus using a conventional hydrostatic fluid bearing is configured as follows.

First, when power is applied to the motor 60, which is only partially shown, and the motor 60 starts to rotate, the polygon mirror 80 also starts to rotate at the same rotational speed as the motor 60.

Subsequently, the vortices formed on the outer circumferential surface and both ends of the rotating shaft 30 by the rotation of the rotating shaft 30 are uniformly introduced into the first groove 40 and the second groove 45 so that the bent portion 60 shows the graph of FIG. 2. As shown in Fig. 1, the tendency of the secondary parabola having a single vertex (a) is shown, and the vertex (a) is the peak fluid pressure that causes the rotation shaft 30 to rise, and the rotation shaft 30 is removed from the bushing part 25 by the generated fluid pressure. It is spaced apart to make contactless rotation.

However, the peak pressure with a single vertex as described above causes the rotary shaft to be spaced apart from the support and the shaft support member (sleeve) for contactless rotation, but the force that separates the shaft from the support and the support member because the peak pressure acts on the rotation shaft is very small. It becomes large in proportion to the peak pressure and the working area. Therefore, if the peak pressure is constant, the working area must be increased to increase the force. However, in the past, the working area is very small due to the bending point, and the force supporting the rotating shaft is also small. Therefore, the rotating shaft is sensitive to minute external shocks or vibrations on the rotating shaft. There was a problem that product performance is deteriorated even in a product requiring ultra precision due to shaking or vibration.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a hydrodynamic type fluid bearing device which stably rotates at high speed by increasing the area of the peak pressure generating portion of the dynamic pressure generating groove. .

1 is a cross-sectional view and a fluid pressure graph showing a conventional dynamic fluid bearing device.

FIG. 2 is an exploded view illustrating the rotating shaft of FIG. 1. FIG.

Figure 3 is a sectional view and a fluid pressure graph showing a hydrostatic fluid bearing device according to the present invention.

Explanation of symbols for the main parts of the drawings

30: rotating shaft 35: first dynamic pressure generating groove

47: first groove 40: second groove

45: third home

The hydrodynamic fluid bearing device according to the present invention for achieving the object of the present invention includes a support member having a bushing portion formed on an inner circumferential surface thereof, and a rotating shaft having a dynamic pressure generating groove formed on one side of the bushing portion and the rotating shaft; In a hydrostatic fluid bearing device including the support member and a bearing bracket for supporting the rotating shaft, the dynamic pressure generating groove has a predetermined length in the axial direction of the rotating shaft, and at regular intervals on the circumference of the rotating shaft. A plurality of first grooves arranged in a plurality, and a second groove and a third groove which are connected to a predetermined length at a predetermined obtuse angle with both ends of the first groove, and are formed by the fluid introduced from the second and third grooves. The fluid pressure is characterized by forming a constant pressure fluid pressure in the first groove.

Hereinafter, the hydrodynamic fluid bearing device according to the present invention will be described with reference to the accompanying drawings, and the same description as in the conventional member will be omitted. The same reference numerals will be used.

3 is an exploded view of a rotating shaft for explaining a dynamic pressure generating groove formed in the rotating shaft of the dynamic fluid bearing apparatus according to the present invention, wherein the first dynamic pressure generating groove 35 is the rotating shaft 30 or the bushing part 25. The first dynamic pressure generating groove 35 formed in the rotary shaft 30 as an example, but a plurality of first dynamic pressure generated in the rotary shaft portion corresponding to the bushing portion 25 The grooves 35 are formed at equal intervals, and the groove area and the number of the first dynamic pressure generating grooves 35 are determined according to the weight and the load applied to the rotation shaft 30.

In addition, the first dynamic pressure generating groove 35 is formed by a turning process, an etching process and a CVD deposition process, and draws virtual lines I and J in the horizontal direction from D and E which are both ends of the bushing part 25, and D, The imaginary lines G and H are drawn again at distances separated by up and down L based on F, the center point of E.

A second groove 40 is formed in the virtual lines I and G, and a third groove 45 is formed in the virtual lines J and H, but the second groove 40 and the third groove 45 are acute with respect to the horizontal (β = 30). And the second groove 40 and the third groove 45 that meet G and H are connected to the first groove 47, which is a straight groove, and the second groove 40 and the third groove. Reference numeral 45 is symmetric with respect to F.

Meanwhile, the thrust bearing 50 having the herringbone or spiral second dynamic pressure generating groove 50a for supporting the thrust load of the rotary shaft 30 and floating the rotary shaft 30 is formed on the rotary shaft 30. One end is supported, the hub 70 is press-fitted in order to rotate the rotation shaft at a predetermined revolution per minute, the rotation shaft 30, the hub 70 is a portion of the motor 60 and the laser beam photosensitive drum The polygon mirror 80 which reflects in (not shown) is provided.

Referring to the accompanying drawings, the operation of the present invention dynamic pressure fluid bearing device configured as described above is as follows.

First, when power is applied to the motor 60, which is only partially shown, and the motor 60 starts to rotate, the polygon mirror 80 also starts to rotate at the same rotational speed as the motor 60.

Subsequently, the vortex formed at the outer circumferential surface and both ends of the rotating shaft 30 by the rotation of the rotating shaft 30 is a fluid inlet of the second groove 40 and the third groove 45. Wow While the second grooves 40 and the third grooves 45 form an inclined surface at an acute angle, the vortex shows a gradually increased fluid pressure while proceeding along the inclined surface to G and H. After reaching, the maximum fluid pressure will be generated.

The first groove 47 is connected to the second groove 40 and the third groove 45 in a straight line. The first groove 47 is formed of a straight portion so that a pressure change does not occur. The fluid having a predetermined pressure introduced to both sides of the first groove 47 gradually crosses at the center portion of the first groove 47 so that the fluid pressure in the first groove 47 is changed to the second groove 40 and the third groove 45. The maximum fluid pressure generated in the) is maintained so that the rotation shaft 30 is spaced apart from the bushing part 25 by a fluid pressure having a wide working area generated in this manner so that the contactless rotation occurs.

As described in detail above, there is an effect of increasing the peak pressure generating portion of the dynamic pressure generating groove to increase the stable support and rotational stability of the rotating shaft to improve product performance.

Claims (2)

A dynamic fluid bearing comprising a support member having a bushing portion formed on an inner circumferential surface thereof, a rotating shaft having a dynamic pressure generating groove formed on one side of the bushing portion and the rotating shaft, and a bearing bracket for supporting the supporting member and the rotating shaft. In the apparatus, The dynamic pressure generating groove has a predetermined length in the axial direction of the rotary shaft, and a plurality of first grooves are arranged at a predetermined interval on the circumference of the rotary shaft, and are connected at a predetermined length while forming a predetermined obtuse angle with both ends of the first groove. The hydrostatic fluid bearing device is formed of a second groove and a third groove, and the fluid pressure generated by the fluid introduced from the second and third grooves forms a fluid pressure having a predetermined size in the first groove. . The hydrostatic fluid bearing apparatus according to claim 1, wherein the area of the peak pressure generating portion is varied by the length of the first groove.