JP2895415B2 - Variable clearance type plain bearings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding bearing for supporting a rotating shaft of a rotary machine, and more particularly to a sliding bearing capable of adjusting an annular clearance between the rotating shaft and a bearing metal supporting the rotating shaft. .

[0002]

2. Description of the Related Art Generally, as shown in FIGS. 2 and 3, a bearing applied to a rotating machine has an annular gap 08 in a bearing metal 02 in which a rotating shaft 01 is fitted and fixed in a bearing hole of a bearing housing 03. The annular gap 08 is filled with lubricating oil. In this type of plain bearing, the annular bearing metal 02 is fixed, so the oil film coefficient cannot be changed during the operation of the rotating machine. Bearings are designed in consideration of balance response characteristics and shaft system stability.

[0003]

The vibration characteristics of the rotating shaft system are determined by the specifications of the shaft system and the oil film characteristics of the bearing. Conventional fixed bearings have problems such as unstable vibration at high speed rotation and a large vibration amplitude when passing a critical speed. The present invention seeks to solve such a problem, and improves the vibration stability at high speed rotation of the rotating shaft system and reduces the vibration amplitude at the time of passing a critical speed. It is intended to provide a bearing.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, a variable clearance type sliding bearing according to the present invention provides a bearing having a bearing housing, a bearing hole formed in the bearing housing, and a bearing hole formed in the bearing housing. A bearing metal fixed and rotatably supporting the rotating shaft with an annular gap, and a radial fitting hole is formed in the bearing metal to slidably fit the bearing pad; A bearing pad formed on a column having an upper surface as a load surface receiving the axial load of the rotary shaft and a lower surface having an area smaller than the upper surface, and slidably fitted in the fitting hole; An oil supply hole for supplying pressure oil is formed on the underside of the bearing pad in the housing.
It is characterized in that it is.

[0005] The variable clearance type sliding bearing according to the present invention is characterized in that the pressure of the pressure oil is adjustable.

[0006]

In the above-mentioned variable clearance type sliding bearing of the present invention, the upper surface of the bearing pad slidably fitted to the bearing metal forms a part of the load surface of the bearing. By changing the radial position of the bearing pad bearing, the size of the gap between the rotating shaft and the bearing metal can be changed. At the time of low-speed rotation, the bearing gap is narrowed in the same manner as a normal fixed type bearing, and the generated oil film pressure is increased to secure an oil film.
In the case where the vibration becomes unstable at the time of high-speed rotation, the gap can be widened to increase the stability.
Also, when approaching the critical speed, the pressure of the pressurized oil is adjusted to adjust the gap appropriately to change the rigidity of the bearing oil film, and to shift the critical speed of the rotating machine and the frequency of the unbalance force to resonate. Can be avoided.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a sliding bearing according to an embodiment of the present invention.

As shown in FIG. 1, the bearing metal 2 is supported (fixed) in a bearing hole formed in a bearing housing 3, and the rotating shaft 1 is supported by the bearing metal 2 through an annular gap 8. I have. A part of the bearing metal 2 is cut out to form a radial fitting hole 2a into which the bearing pad 4 is slidably fitted.

The bearing pad 4 has an upper surface 4a as a load surface for receiving the axial load of the rotating shaft 1, and a column having a projection 4b formed on a surface opposite to the upper surface and having a lower surface 4c smaller in area than the upper surface. The projection 4b is formed on the bearing
Is slidably fitted in a hole 3a formed in the inner peripheral surface of the rim. A gap between the lower surface 4c of the projection 4b of the bearing pad 4 and the bottom surface of the hole 3a of the bearing housing 3 is defined as a pressure chamber 5, and an oil supply hole 6 for supplying oil pressure to the pressure chamber 5 from the outside penetrates the bearing housing 3. By changing the oil pressure of the oil supplied to the pressure chamber 5 through the oil supply hole 6 from the outside, the radial position of the bearing pad 4, that is, a part of the annular gap 8 can be adjusted. Has become.

With this configuration, the rotating shaft 1 and the bearing pad 4
At the time of low speed rotation, the bearing gap is narrowed to secure the generated oil film pressure. On the other hand, when the vibration becomes unstable at the time of high-speed rotation, the clearance between the rotating shaft 1 and the bearing pad 4 can be widened to increase the stability. When the critical speed approaches, by appropriately adjusting the gap between the rotating shaft 1 and the bearing pad 4, the rigidity of the bearing oil film is changed to shift the critical speed of the rotating machine and the frequency of the unbalance force. , Resonance can be avoided.

[0011]

With the fixed plain bearing, the oil film coefficient cannot be changed during the operation of the rotating machine, and the speed, unbalanced response characteristics, shaft system stability, etc. are changed in advance when the operating conditions such as rotation speed and load are changed. The bearing must be designed in consideration of the excessively high quality, but according to the variable clearance type sliding bearing of the present invention, the excessive quality can be prevented as described above, and the rotation shaft system can be prevented. A sliding bearing with improved vibration stability during high-speed rotation and reduced vibration amplitude when passing a critical speed can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a variable clearance type plain bearing as one embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a conventional fixed type plain bearing.

FIG. 3 is a sectional view taken along the line AA of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating shaft 2 Bearing metal 2a Fitting hole 3 Bearing soldering 3a hole 4 Bearing pad 4a Upper surface 4b Projection 4c Lower surface 5 Pressure chamber 6 Oil supply hole 8 Annular clearance

Claims (2)

(57) [Claims] 1. A plain bearing comprising: a bearing housing; a bearing hole formed in the bearing housing; and a bearing metal fixed to the bearing hole and rotatably supporting a rotary shaft with an annular gap. A radial fitting hole is formed in the bearing metal so that the bearing pad can be slidably fitted therein, and the bearing pad is smaller than the upper surface as an upper surface as a load surface receiving the axial load of the rotating shaft. An oil supply hole that is formed in a column having an area lower surface and that is slidably fitted in the fitting hole, and that is capable of supplying pressure oil to the lower surface of the bearing pad in the bearing housing; Characterized by
Variable clearance type plain bearing. 2. The sliding bearing according to claim 1, wherein the pressure of the pressure oil is adjustable.