JPS61201917A - Floating bush bearing - Google Patents

Abstract

PURPOSE:To suppress the vibration of a bush in its high speed rotation, by forming the internal peripheral surface of the bush in a shape which provides plural circular arc surfaces of respectively different center of curvature continuing in the peripheral direction. CONSTITUTION:A bush 10 in a cylindrical shape interposes, spacing clearances 3, 4, between a rotary shaft 1 and a supporting body 2 surrounding the rotary shaft 1, and said bush 10 forms its internal peripheral surface in a shape continuing two circular arc surfaces 11a, 11b. The center of curvature of these circular arc surfaces 11a, 11b, being placed in an eccentric position in an opposite direction to each other with respect to the center of a peripheral surface of the bush 10, is different also in accordance with a diameter of the rotary shaft 1 and its rotary speed, but a distance of eccentricity is set to about 1/10mm when the rotary shaft 1 is in an about, for instance, 200mm diameter.

Description

[Detailed description of the invention] <Industrial field of application> and outer periphery The present invention relates to a rotating shaft, a support for supporting
A cylindrical block that floats due to the dynamic pressure of lubricating oil while
This invention relates to a floating bush bearing with an oil bush.

Radial direction (conventional technology)
As shown in FIG. 3, which shows the structure of a conventional floating bush bearing in contact with the body, the outer peripheral surface 1a of the rotating shaft 1
Even during this rotation, the shoe 5 can freely rotate relative to the rotation axis l. Then, the rotating shaft 1 starts rotating through the gap 4.
Dynamic pressure is applied to the lubricating oil supplied to the bushing 5.
When the bushing 5 floats within the supporting body 2, the bushing 5 also rotates due to the co-existing viscosity, and dynamic pressure is applied to the lubricating oil supplied to the rotating shaft 3, causing the bushing 5 to float within the support 2, resulting in a bearing with low overall frictional resistance. The problem that Noda is trying to solve is a floating bush bearing in which the inner peripheral surface and surface of the bush are formed in a perfect circle, and the gap is also a perfect circle. This caused an unstable footing situation, causing vibrations that caused the bushing to come into contact with the rotating shaft and support.

The floating bush bearing of the present invention has the belief that it can rotate at a higher speed than the conventional one and float stably without the bushing moving. In a floating bush bearing in which a cylindrical bush rotatable relative to the rotating body is interposed between a support body that surrounds and supports the shaft, the inner peripheral surface of the bush has a plurality of bushes each having a different center of curvature. It is molded into a shape in which the circular arc surface is continuous in the circumferential direction.

<Operation> When the rotating shaft starts rotating, dynamic pressure is generated in the lubricating oil interposed between the rotating shaft and the bushing, causing the rotating shaft to levitate within the bushing, and the viscosity of the lubricating oil causes the bushing to rotate along with it. The bushing is rotated and floats within the support. At this time, since the inner circumferential surface of the bushing is formed of multiple arcuate surfaces with different centers of curvature, the shape of the oil film formed between the shaft of one rotation and the bushing changes as the bushing rotates, causing vibrations in the bushing. With improved characteristics, the bushing continues to float stably even at higher speeds.

<Embodiment> As shown in FIG. 1 showing the cross-sectional structure of an embodiment of the floating bush bearing according to the present invention, there is a gap 3.4 between the rotating shaft 1 and the support body 2 surrounding the rotating shaft 1. A cylindrical bushing is interposed between the inner circumferential surface of the bushing 10 and the inner peripheral surface of the bushing 10 is formed into a continuous shape. The centers of curvature are eccentric in opposite directions relative to the center of the outer peripheral surface of the bushing 10, and vary depending on the diameter and rotation speed of the rotating shaft 1.
For example, in the case of the rotating shaft 1 having a diameter of about 200 mm, the eccentricity is set to about 1/io mm.

A floating bush bearing using such a bush 10 can be operated by rotating the rotary shaft 1, as in the conventional case.
0 rotates in a state where it floats across gaps 3 and 4. However, during this rotation, the shape of the oil film within the gap 4 changes and the rotational speed at which oil whip occurs shifts to a higher side, so that vibrations are prevented from occurring even at higher rotations.

In addition, in this embodiment, the case where two circular arc surfaces 11a, 1 lbt.
As shown in FIG. 2, which shows the cross-sectional structure of the bushing in another embodiment of the present invention, the circumferential surface of the bushing 20 has three or more (
In the illustrated example, the three arcuate surfaces 21a, 21b, and 21ct may be continuous, and even in this case, the bush will vibrate even when rotated at a higher speed than a bush with a perfectly circular inner peripheral surface. do not.

<Effects of the Invention> According to the floating bush bearing of the present invention, it is possible to shift the rotational speed at which oil whip occurs to a higher side, and it is possible to achieve stable floating even at higher speeds compared to the conventional floating bush bearing, resulting in a highly reliable floating bush bearing. is obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of a floating bush bearing according to the present invention, FIG. 2 is a longitudinal sectional view of a bushing portion in another embodiment of the invention, and FIG. 3 is a longitudinal sectional view of a conventional floating bush bearing. FIG. Further, in the figure, 1 is a rotating shaft, 2 is a support, 3.4 is a gap, 10.20 is a bush, and 11a. 11b, 21a to 21C are circular arc surfaces.

Claims (1)

[Claims] In a floating bush bearing in which a cylindrical bushing rotatable relative to the rotating shaft is interposed between a rotating shaft and a support that surrounds and supports the rotating shaft, the inner circumferential surface of the bushing is curved. A floating bush bearing that is formed into a shape in which multiple arcuate surfaces, each with a different center, are continuous in the circumferential direction.