JP3310826B2 - Dynamic pressure gas journal bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic gas journal bearing used for high-speed turbo machines such as expansion turbines and compressors.

[0002]

2. Description of the Related Art Conventionally, a dynamic pressure gas journal bearing as described in Japanese Patent Application Laid-Open No. 3-24319 has been known as a bearing device for equipment requiring high-speed rotation.
This will be described with reference to FIG. 9. In FIG. 9, reference numeral 101 denotes a housing, 102 denotes a rotating shaft, and 103 denotes a cylindrical sleeve interposed between the housing 101 and the rotating shaft 102 so as to surround the rotating shaft 102. And is provided in the housing 101 as shown.

[0003] Reference numeral 104 denotes a bearing pad made of a porous material, which is provided at both ends of the housing 101. Each bearing pad 104 is provided on the housing 101.
A gas, for example, air is supplied to the bearing pad 104 from the gas supply source 120 via the gas supply passage. The gas supplied to the bearing pad 104 is
The gas is ejected from the bearing pad 104 toward the sleeve 103, and then discharged to the outside of the housing 101 via the exhaust passage 109.

[0004] Reference numeral 105 denotes a herringbone groove for generating dynamic pressure formed on the surface of the rotating shaft 102 along the direction of rotation thereof. As shown in the figure, the herringbone groove is located near both ends of the housing 101. In addition, it is formed at two places on the rotating shaft 102. An air layer (spacing) 106 is formed between the housing 101 and the sleeve 103, and an air layer (spacing) 107 is formed between the sleeve 103 and the rotating shaft 102. The air layer 106 and the air layer 107 are completely shut off by the sleeve 103.

In this configuration, when the rotating shaft 102 is stopped or rotating at a low speed, the rotating shaft 102
03 is supported by the sleeve 103 in a state of being in contact therewith. On the other hand, the sleeve 103 is rotatably supported in a non-contact manner with respect to the housing 101 (bearing pad 104) by a hydrostatic bearing constituted by gas ejected from the bearing pad 104 to the air layer 106. . Therefore, at this time, the rotating shaft 102 rotates while being supported by the hydrostatic bearing integrally with the sleeve 103.

Thereafter, when the rotation speed of the rotary shaft 102 gradually increases, the viscous resistance of the air layer 106 between the housing 101 and the sleeve 103 increases, and the viscous resistance increases.
When the force becomes larger than the maximum static frictional force between the rotating shaft 102 and the sleeve 103, a relative rotation difference is generated between the rotating shaft 102 and the sleeve 103.
A dynamic pressure is generated between the sleeve 2 and the sleeve 103 by the herringbone groove 105.

Further, when the rotation speed of the rotation shaft 102 increases and the rotation speed of the rotation shaft 102 becomes a steady rotation speed, the dynamic pressure (dynamic pressure bearing) generated by the herringbone groove 105 causes the rotation shaft 102 to rotate. 102 is supported by the sleeve 103 in a non-contact state. That is, at this time, the sleeve 10 is provided by a hydrostatic bearing between the housing 101 and the sleeve 103.
3 is supported in a non-contact manner with respect to the housing 101, and the rotating shaft 10
The rotating shaft 102 is supported by the dynamic pressure bearing between the sleeve 2 and the sleeve 103 in a non-contact manner with respect to the sleeve 103.

At this time, the angular velocity ω of the sleeve 103 is such that the radial thickness of the air layer 106 is h ₁ (about 5 to ₁₀ μm), and the radial thickness of the air layer 107 is h ₂ (about 5 to 10 μm). If the angular velocity of the rotating shaft 102 is ω ₀ , it is expressed by the following [Equation 1].

(Equation 1) However, the radial thickness t of the sleeve 103 is
Is sufficiently smaller than the shaft diameter d.

Therefore, when the rotation speed of the rotating shaft 102 becomes a steady speed, the sleeve 103 also rotates at a desired speed lower than the rotating speed of the rotating shaft 102. For this reason, even when the rotating shaft 102 expands in the radial direction due to centrifugal force during high-speed rotation, the inner and outer diameters of the sleeve 103 are also expanded, so that there is no contact between them. Also the sleeve
Since the angular velocity ω of the shaft 103 is smaller than the angular velocity ω ₀ of the rotating shaft 102, the swelling due to the centrifugal force is small, and even if the thickness h ₁ in the radial direction of the air layer 106 is not so large, the sleeve 103
Can be prevented from contacting the bearing pad 104. That is, contact during high-speed rotation can be prevented without reducing the rigidity of the hydrostatic bearing.

In the above-described dynamic gas journal bearing (shown in FIG. 9), the sleeve 103 is supported by the gas supplied from the gas supply source 120 in a floating state in the casing 101.
Instead, a sleeve supporting structure as shown in FIGS. 7 and 8 has been conventionally proposed. FIG. 7 shows a bump foil type journal bearing, in which a bearing gap 6 is provided around the rotating shaft 1 (the bearing gap 6 is the air layer 107 of FIG. 9).
The bearing cylinder 2 (top foil, corresponding to the sleeve in FIG. 9) arranged at a distance therebetween is elastically supported by the housing 4 via the bump foil 17. I have.

When a load is applied to the rotating shaft 1, the bearing cylinder 2 is deformed so as to fit the rotating shaft 1, and this deforms the bump foil 17 and causes the bump foil 17 to deform.
Slip occurs at the contact surface between the housing 17 and the housing 4 to provide bearing damping. FIG. 8 shows a leaf foil type journal bearing, in which a plurality of leaf foils 18 are arranged so as to partially overlap each other around a rotating shaft 1 with a bearing gap 6 therebetween. With the action of the axial load, the leaf foil 18 is deformed so as to fit to the rotating shaft 1, but at this time, friction occurs between the leaf foils 18 at the foil contact portion 19 to assist the bearing in damping. I have.

[0012]

In the conventional dynamic pressure gas journal bearing shown in FIGS. 7 and 8 in which the bearing surface is made of an elastic body, when the load changes during operation, (1) no Under a load or an extremely light load, in the case of the bump-foil type, the bearing cylinder has a small deformation amount and is in an operating state similar to that of a rigid round bearing, and thus lacks stability. In this regard, the leaf foil bearing has a multi-faceted bearing surface, and the lubricating film pressure is generated throughout the bearing, so that the vibration suppression effect is high even when there is no load. (2) On the other hand, in the case of heavy load, the bump foil type can withstand heavy load by adjusting the rigidity of the bearing cylinder and the bump foil, but the leaf foil type can increase the rigidity of the foil foil is difficult and Ageruko structural rigidity has become a simple support structure,
The withstand load limit becomes lower. For these reasons, there is a problem in that the bearing whose bearing surface is formed of an elastic body is limited to an application range of a self-weight bearing type rotary machine or a vertical type rotary machine having no load change during operation. An object of the present invention is to provide a dynamic pressure gas journal bearing which has solved such a problem.

[0013]

[SUMMARY OF] To achieve the above object, hydrodynamic gas journal bearings of the present invention is disposed at a same rotation shaft and the bearing clearance to the outside of the rotating shaft metal or other A bearing cylinder made of a thin plate of an elastic body, a housing which is disposed outside the bearing cylinder with a gap therebetween and is more rigid than the bearing cylinder, and the bearing cylinder and the housing
And an outer peripheral surface of the bearing cylinder
The inner end of the intermediate cylinder extends
A plurality of first ribs which can be inscribed on the surface, and
The inner peripheral surface of the housing extends axially on the peripheral surface.
And a plurality of second ribs that can be inscribed in the bearing circle,
The outer peripheral surface of the cylinder, the first rib and the inner peripheral surface of the intermediate cylinder
Reach the above space to supply cooling fluid to the space
A cooling fluid supply hole is provided .

Further , the dynamic pressure gas journal bearing of the present invention.
Are the outer peripheral surface of the intermediate cylinder, the second rib, and the housing.
Rubber, polymer gel in the space defined by the inner peripheral surface of the
Or make sure that vibration damping material such as powder is
Features.

[0015]

In the above-described dynamic gas journal bearing of the present invention,
Since the bearing cylinder is made of an elastic material,
Adjust the thickness to give appropriate rigidity to the load
And there is no problem with the structural load capacity.

Further , a support portion provided on the outer periphery of the bearing cylinder
Compression on the inner diameter side of the bearing cylinder through the ribs
In this way, the inner surface of the bearing cylinder is
To the extent that the bearings have
Effective formation of synovium, effective even under no load
It can exhibit various bearing characteristics.

Further, the cooling action of the bearing portion by the cooling fluid.
Is also performed. Also, due to the vibration damping material enclosed in the space,
Thus, an action of damping the vibration of the rotating shaft is performed.

[0018]

EXAMPLES Hereinafter, as for hydrodynamic gas journal bearing as an embodiment of the present invention will be described with reference to the drawings, FIG. 1 is first
Sectional view of the bearing surface of the examined example, FIG. 2 is a sectional view of a bearing surface of the second study example, FIG. 3 (a) ~ (c) is an enlarged view of a part III of FIG. 1 in cross-sectional view of a modification of the rib , cross-sectional view of Figure 4 the bearing surface of the third study example, FIG. 5 (a) is a cross-sectional view of a bearing surface of the first real施例, FIG. 5 (b) a-a arrow in FIGS. 5 (a) sectional view, FIGS. 6 (a) is a sectional view of a bearing surface of the second actual施例, FIG. 6 (b) a B-B cross-sectional view taken along FIGS. 6 (a).

First, a first study example will be described with reference to FIG. In the first study example as well, a bearing cylinder 2 made of a thin plate of metal or other elastic material is disposed around the rotating shaft 1 with an appropriate bearing clearance (distance for dynamic pressure gas) 6. The bearing cylinder 2 has a structural rigidity suitable for bearing performance due to its thickness and the arrangement interval of the plurality of ribs 3 provided on its outer periphery. In this study example , four ribs 3 are provided at 90 ° intervals. Reference numeral 4 denotes a housing, and reference numeral 5 denotes a bearing rear space formed by the bearing cylinder 2, the housing 4, and the rib 3. Also, the inner diameter of the housing 4 is set smaller than the virtual circumscribed circle of the rib in the free state, and when the bearing cylinder 2 and the rib 3 are inserted into the housing 4, the bearing cylinder 2 is distorted in a non-circular state in advance. You can do it.

With this configuration, even in the case where the center of the rotating shaft 1 is operated near the center of the housing 4 with a very light load, the bearing gap 6 formed by the rotating shaft 1 and the bearing cylinder 2 can be formed. The shape can maintain the wedge shape, the pressure of the lubricating film can be easily generated, and the effect of increasing the stability of the shaft system can be obtained. In addition, by increasing the rigidity of the rib 3, the load capacity can be increased, and stable bearing performance can be exhibited even under a high load.

Next, a second study example will be described with reference to FIG.
In the first study example described above, although the performance of the lubricating film itself in the conventional example is improved, there is no assistance in decelerating the bearing by the friction effect of the foil. In this second study example , the first study
A bearing damping material (vibration damping material) such as an anti-vibration rubber, a polymer gel, or powder is provided in a bearing rear space (first space) 5 including the bearing cylinder 2, the housing 4, and the ribs 3 in the example .
7a is enclosed. In the second study example , with this configuration, it is possible to cause a time delay in the deformation of the bearing cylinder 2 with respect to the vibration of the rotating shaft 1, thereby providing the above-described effect of the first study example and the vibration damping effect. Can be improved.

FIG. 3 shows a modified example of the rib 3 in the first and second examination examples. The rib indicated by reference numeral 3a in FIG. 3 (a) is constituted by a flexible circular tube. The rib 3a is configured to allow deformation. As a result, stable operation can be guaranteed even when the load direction of the bearing load changes. The rib indicated by reference numeral 3b in FIG. 3 (b) is formed of a mountain-shaped spring, and if the housing 4 and the ribs 3b are allowed to slide on both skirts 31b, 31b,
The same friction damping effect as the conventional bump foil bearing can be imparted to the bearing characteristics. Further, as shown by reference numeral 3c in FIG. 3 (c), the rib is constituted by an elastic body having a triangular cross section so as to be rotatably supported between the rib 3c and the surface of the housing 4. When setting relatively rigid,
The optimum gap shape can be autonomously formed by the inclination of the rib, and the load capacity can be improved.

Next, a third study example will be described with reference to FIG.
In the third study example , the bearing cylinder has a double structure with an intermediate cylinder 8 interposed between the bearing cylinder 2 and the casing 4 in the first study example . The intermediate cylinder 8 is also provided with four second ribs 8 at intervals of 90 °. When the bearing cylinder 2 and the intermediate cylinder 8 are assembled to the casing 4, the second ribs 8 and the ribs 3 (hereinafter referred to as “ 1 rib 3 ”) at 45 ° intervals. In the first study example , the bearing characteristics become non-uniform in the circumferential direction depending on the position of the first rib 3, and the design becomes complicated when the load direction changes. However, in the third study example , this can be avoided. .

That is, as shown in FIG. 4, when the first ribs 3 are arranged in the vertical and horizontal directions and the intermediate cylinder 8 is not provided, when the load applied to the rotary shaft 1 is vertically downward, The bearing cylinder 2 and the first rib 3 come into direct contact with the housing 4 and the rigidity of the first rib 3 causes the bearing cylinder 2
Becomes difficult to deform. On the other hand, by providing the intermediate cylinder 8, when the rotating shaft 1 receives a load vertically downward, the first rib 3 and the bearing cylinder 2 existing in that direction are displaced downward. This is transmitted to the intermediate cylinder 8 and the intermediate cylinder 8
Is distorted vertically, which causes the horizontal 2
The two first ribs 3 distort the bearing cylinder 2 vertically, and the effect of the deformation is that the first rib 3 does not exist in the load direction .
The same deformation effect as in the first study example can be produced.

When damping is imparted by enclosing the vibration damping material 7a, such as the vibration-isolating rubber, polymer gel, or powder, shown in the second study example , in the space behind the bearing, there are two of the two spaces. It is appropriate to enclose in the outer space (third space) 7 formed by the intermediate cylinder 8, the second rib 9 and the bearing housing 4. This is because the space 7 formed by the bearing cylinder 2, the intermediate cylinder 8, and the second rib 9 moves due to deformation, thereby generating an inertial force, and there is a possibility that the expected bearing performance cannot be exhibited.

Furthermore, FIG. 5 (a), illustrating a first actual施例by (b). The first real施例penetrates the space 7 enclosed housing 4 and anti-vibration rubber and the like from the outside of the bearing in the third study example, the bearing back space of the cooling fluid 12 to reach the (second space) 5A A supply hole 10 is provided. Sign
Reference numeral 11 denotes a supply groove for the cooling fluid 12 formed on the outer peripheral surface of the housing 4. The supply groove 11 communicates with the supply hole 12. This is a cooling fluid from outside for the purpose of removing frictional heat generated when the shaft rotation speed is extremely high.
The cooling effect is measured by supplying 12 to the bearing back space 5A and discharging it from the bearing side.

In the prior art, the influence of the thermal elongation of the shaft is not important because the structural elasticity of the foil is generally small.
In hydrodynamic gas journal bearings of the present invention taking high structural rigidity of the bearing for heavy duty bearings, and when used in high speed, the cooling is important because a gap is clogged easily structure, the first actual施例is This is to deal with this. Second actual施例in FIG 6 (a), (b) is, FIG. 5 (a), the first shown in (b)
An improvement of the real施例parallel to form a supply hole 10 and the rotary shaft 1,
In order to prevent the fluid 12 supplied from the supply hole 10 from leaking from the side end of the casing 4, an outer peripheral wall 13 and an inner peripheral wall 15 are protruded from one side end of the casing 4, and the inner peripheral wall 13 and the inner peripheral wall 13 are formed. The bellows 14 is stretched between the peripheral wall 15.

With this configuration, the cooling fluid 12 is guided to the radial passage 16 surrounded by the bellows 14 at one end of the casing 4,
From here, the fluid can be cooled through the bearing back space 5 to cool the bearing. In this embodiment, FIG.
This structure is optimal for applications in which the cooling fluid 12 is not desired to leak to the right side of the radial passage 16. The fluid 12 is shown in FIG.
It is supplied from the left side in (b). Although in FIG. 6 (b) shows an example in which the radius passage 16 at one side end portion of the casing 4, providing a radius passage side end portions of the combination casing 4. At the first actual施例Thus, the gas flowing through the bearing gap 6 and the cooling fluid 12 can be separated.

[0029]

As described above, according to the dynamic pressure gas journal bearing of the present invention, the following effects and advantages can be obtained. (1) Stable bearing performance can be exhibited from no load to high load. As a result, not only the bearings of the self-weight bearing type, such as rotary machines and vertical machines, but also the performance of both bearing stability at no load and load-bearing capacity at rated load, such as compressors with built-in gearboxes And the present invention can be applied to these machines to simplify the seal system and make the structure compact. (2) Since the bearing structure can be simplified, the manufacturing cost is lower than that of a conventional gas bearing made of a rigid body, and the bearing clearance can be easily set, so that the assembly cost can be reduced. (3) Since effective cooling can be performed, the present invention can be applied to a heavy-duty bearing having a high structural rigidity.

[Brief description of the drawings]

FIG. 1 is a sectional view of a bearing surface of a dynamic pressure gas journal bearing as a first study example .

FIG. 2 is a sectional view of a bearing surface of a dynamic pressure gas journal bearing as a second study example .

FIG. 3A is a sectional view of a modification of the rib. (b) Sectional drawing of the modification of the same rib. (c) Sectional drawing of the modification of the same rib.

FIG. 4 is a sectional view of a bearing surface of a dynamic pressure gas journal bearing as a third study example .

5 (a) cross-sectional view of the bearing surface of the dynamic pressure gas journal bearing as a first actual施例. 5B is a sectional view taken along the line AA in FIG.

6 (a) is a cross-sectional view of the bearing surface of the dynamic pressure gas journal bearing as a second actual施例. (b) A sectional view taken along the line BB in FIG. 6 (a).

FIG. 7 is a sectional view of a bearing surface of a bump foil type bearing in a conventional dynamic pressure gas journal bearing.

FIG. 8 is a cross-sectional view of a bearing surface of a leaf foil type bearing in a conventional dynamic pressure gas journal bearing.

FIG. 9 is a sectional view of a bearing surface of a conventional dynamic pressure gas journal bearing.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 rotating shaft 2 bearing cylinder 3 first rib 4 housing 5 bearing back space (first space) 5A second space 6 bearing gap 7 third space 7a vibration damping material such as rubber, polymer gel or powder 8 intermediate Cylinder 9 Second rib 10 Cooling fluid supply hole 11 Supply groove 12 Cooling fluid 13 Outer wall 14 Bellows 15 Inner wall 16 Radial passage 17 Bump foil 18 Leaf foil 19 Foil contact

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16C 17/00-17/26 F16C 21/00-27/08 F16C 33/00-33/28 F16C 35/00-43 / 08

Claims (2)

(57) [Claims] 1. A dynamic pressure gas journal bearing, comprising: a metal or other elastic thin-plate bearing cylinder disposed outside the rotary shaft with a bearing gap between the rotary shaft and a bearing cylinder; a housing disposed consisting rigid cylindrical body than the bearing cylinder at a gap, disposed intermediate cylinder between the bearing cylinder and the housing
And an outer end surface extending axially on the outer peripheral surface of the bearing cylinder.
A plurality of first ribs which can be inscribed on the inner peripheral surface of the intermediate cylinder
Extending axially on the outer peripheral surface of the intermediate cylinder and
A plurality of second ribs that can be inscribed on the inner peripheral surface of the housing;
Of the outer peripheral surface of the bearing cylinder, the first rib and the intermediate cylinder,
To supply cooling fluid to the space defined by the peripheral surface
A cooling fluid supply hole reaching the space is provided.
A dynamic pressure gas journal bearing characterized by the above-mentioned . 2. An anti-vibration rubber is provided in a space defined by the outer peripheral surface of the intermediate cylinder, the second rib, and the inner peripheral surface of the housing.
The dynamic pressure gas journal bearing according to claim 1, wherein a vibration damping material such as a polymer gel or a powder is sealed.