JPH0128336Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to fluid bearing structures for gas, oil, water, steam, etc., and in particular to a foil bearing using elastic foil, which exhibits excellent high-speed stability. The present invention relates to a hydrodynamic bearing structure that can dramatically improve manufacturability.

[Technical background of the invention and its problems] Fluid bearings are bearings that form a high-pressure fluid film between the rotating shaft and the bearing surface and support the rotating shaft using this fluid film pressure. It has the characteristics of low friction loss and high load capacity, and is extremely effective as a bearing for high-temperature or low-temperature high-speed rotating shafts such as turbo compressors, turbo expanders, turbo chargers, and turbo refrigerators.

Rigid bearings and foil bearings are known as gas bearings. In rigid bearings, the gas film breaks due to shaft deformation, etc., so foil bearings are currently being researched and developed.

However, in general, when the bearing surface of a gas bearing is of a high load capacity type such as a plain, spiral group, or pocket type, there is a problem that self-excited vibration is induced in the high-speed rotation range, resulting in instability.

The applicant of the present application previously proposed a "hydrodynamic bearing structure" that can eliminate such self-excited vibration phenomena extremely effectively (Japanese Patent Application No. 58-242082).

This proposal releases part of the fluid film pressure to the outside of the bearing surface in order to prevent excessive fluid film pressure from occurring on the bearing surface, and uses this released pressure effectively as external damping. This is achieved by

However, although the above proposal has extremely excellent effects, it requires a large number of parts as shown in FIG. 11, and also has the problem of technical difficulties in molding each foil into a cylindrical surface.

That is, in the above proposal, a spring foil d inserted through a bearing foil a, a dump oil b, and a lattice foil c so that its teeth appear alternately on the front and back is laminated, and a key member e is joined to one end of the spring foil d. At the same time, although these are molded into cylindrical surfaces, there is a problem in that the work is relatively difficult and manufacturability is low.

[Purpose of the invention] The present invention was devised in view of the problems mentioned above, and its purpose is to create a fluid bearing that can dramatically improve the manufacturability of bearings that exhibit excellent high-speed stability. It is there to provide structure.

[Summary of the invention] According to the present invention, the above object is achieved by the following configuration.

That is, in a fluid bearing that is formed by laminating an elastic foil on a bearing surface and supports a rotating shaft by fluid film pressure, the bearing foil forms a fluid film on the bearing surface, the bearing foil and the support. A damp oil provided between the bearing surface and the bearing surface for damping vibrations, and a spring oil for elastically supporting the damp oil on the bearing surface are connected to the elastic band-shaped oil body along its longitudinal direction. The elastic band-shaped oil body is formed by winding the bearing oil, dump oil, and spring oil in the longitudinal direction so as to overlap each other in a laminated manner.

[Embodiments of the invention] Preferred embodiments of the invention will be described in detail below with reference to the accompanying drawings.

In this embodiment, a plain type bearing of a Jarnalf oil bearing is exemplified.

FIG. 1 shows the mounting state of a bearing having a structure according to the present invention.

As shown in the figure, 1 is a rotating shaft of a turbo compressor or the like, and an annular bearing case 2 is provided around the outer periphery of this rotating shaft 1 . Between the rotating shaft 1 and the bearing surface 3 on the inner circumference of the bearing case 2,
A bearing 4 is provided for supporting the rotating shaft 1 by gas film pressure. This bearing 4 is constructed by laminating elastic foils, and the feature of the present invention lies in the structure of this bearing 4.

As shown in FIGS. 2 and 3, reference numeral 5 denotes an elastic band-shaped foil body formed with a length approximately three times the inner circumferential length of the bearing case 2, which serves as the bearing surface 3 of the bearing 4. By winding it up, it is molded to a length that will form a coil body of approximately three layers inside the bearing surface 3. A bearing foil 6, a damping foil 7, and a spring foil 8 are continuously formed on the elastic band-shaped foil body 5 along its longitudinal direction. These foils 6, 7, and 8 are arranged so that each layer is formed when the elastic band-shaped foil body 5 is rolled up in approximately three layers.
Each of the elastic band-shaped foil bodies 5 has a length of approximately 1/3 of the total length of the elastic band-shaped foil body 5.

The bearing foil 6 forming the innermost layer of the bearing 4 is
One end of the elastic strip-shaped foil body 5 (right end in the figure)
It is formed over approximately 1/3 of the area. This bearing oil 6 is disposed closest to the rotating shaft 1, and forms a gas film on the inner peripheral bearing surface 9 (FIG. 1). In the illustrated example, a plain bearing surface 9 with a smooth bearing surface 9 is shown. A plurality of damping orifices 10 are formed in the bearing foil 6 at the center thereof in the width direction, passing through the bearing oil 6 in the plate thickness direction at appropriate intervals along the longitudinal direction.

This damping orifice 10 functions to release the excess pressure of the gas film formed on the bearing surface 9, regulate the pressure of the gas film on the bearing surface 9, and suppress excessive pressure rise.

Spring oil 8 forming the outermost layer of the other bearing 4
is formed over approximately ⅓ from the other end (left end in the figure) of the elastic strip-shaped foil body 5. This spring oil 8 is provided on the bearing surface 3 and elastically supports the dump oil 7 in order to resiliently support the gas film pressure acting on the bearing oil 6 from the bearing surface 3 (FIG. 1). In this embodiment, the springfoil 8 is provided with a rudderfoil 12 in which teeth 11 in the form of a vertical lattice are formed at regular intervals along the longitudinal direction. This ladder oil 12
is assembled so that its teeth 11 appear alternately on the front and back sides of the spring oil 8, and functions to improve the elasticity of the spring oil 8. In addition, at the end of this spring oil 8 that constitutes the outermost layer of the bearing 4,
The key member 13 is joined. This key member 13
is fixed in a key groove 14 formed by recessing in the bearing surface 3 of the bearing case 2, and is configured to fix an elastic band-shaped oil body 5, in which the spring oil 8 and the like are formed in series, to the bearing case 2. Ru.

A damp oil 7 forming an intermediate layer of the bearing 4 is provided in the intermediate portion of the elastic band-shaped oil body 5 between the spring oil 8 and the bearing oil 6 configured as described above.
is formed. This damping oil 7 has a spring oil 8 in frictional contact with its outer periphery, and its inner periphery faces the inner periphery of the bearing oil 6 in which a damping orifice 10 is formed. The damping oil 7 is configured to exhibit a vibration damping function using the excess pressure of the gas film on the bearing surface 9 introduced from the damping orifice 10 of the bearing oil 6 (FIG. 1). In this embodiment, a damping pocket 15 is formed in the damping oil 7 to correspond to the damping orifice 10 and to a depth of approximately half the thickness of the damping oil. This damping pocket 15
When the elastic band-shaped foil body 5 is rolled up,
It is arranged so as to face the damping orifice 10.

Next, the operation of the present invention will be described.

First, when manufacturing the bearing 4, an elastic band-shaped foil body 5 is molded to a predetermined length, and then a damping orifice 10 and a damping pocket 15 are formed in the bearing foil 6 and damping foil 7 of the foil body 5, respectively, by photo etching or the like. . Further, the bearing surface 9 of the bearing oil 6 is coated with a suitable wear-resistant coating. On the other hand, a pre-shaped rudder oil 12 is attached to the spring oil 8, and then a key member 13 is joined to the end of the spring oil 8. As described above, the bearing foil 6 is continuously applied to the elastic band-shaped foil body 5 along its longitudinal direction.
Dump oil 7 and spring oil 8 are formed.

Next, the elastic strip-shaped foil body 5 and the bearing 4 configured in this way are formed, and when mounted on the bearing case 2, the elastic strip-shaped foil body 5 is rolled up in the longitudinal direction of the bearing case 2 so as to be slightly larger than the inner diameter of the bearing case 2. By forming a cylindrical body with approximately three layers, narrowing the cylindrical body, and inserting the key member 13 along the key groove 14 of the bearing case 2, the elastic strip-shaped foil body 5 expands in diameter and is supported within the bearing case 2. The bearing 4 is in close contact with the surface 3, and the respective foils 6, 7, and 8 are also in close contact with each other in a layered manner, so that a predetermined bearing 4 can be formed.

In the hydrodynamic bearing structure of the present invention constructed as described above, the respective foils 6, 7, and 8 are formed all at once in one elastic band-shaped foil body 5.
Since the bearing 4 can be constructed by simply winding up the bearing 4, the number of parts is small, and cylindrical surface molding is easy, which simplifies the manufacturing work and significantly improves manufacturability. Therefore, cost reduction can be achieved. Furthermore, if each foil is formed and assembled independently, there is a risk that the assembly error will become large, but according to the present invention, each foil 6, 7, 8 is attached to a series of elastic band-shaped foil bodies 5 at a predetermined pitch. Since it is formed by forming the bearing, the elements that cause errors can be reduced to the bearing surface 3 of the bearing case 2, the plate thickness of the foil body 5, etc., and high accuracy and reliability can be ensured. In addition, the rolled-up elastic band-shaped foil body 5 naturally expands in diameter within the bearing case 2 due to its elasticity, allowing the foils 6, 7, and 8 to be brought into close contact with each other, with extremely small gaps, allowing for high-precision assembly. At the same time, sufficient bearing performance can be ensured. Also, centering accuracy can be improved.

In the above embodiment, the bearing oil 6 is shown as a plain bearing oil, but it may be formed into a spiral groove, a tapered land, a pocket, or the like.

Next, the function of the hydrodynamic bearing structure according to the present invention will be explained.

As shown in FIGS. 1 and 4, when the rotating shaft 1 rotates in the direction of the arrow R, hydrodynamic pressure is generated in the bearing gap H due to the entrainment action based on the viscosity of the fluid. As a result, the springf oil 8 sandwiched between the rudderfoils 12 deforms into a wave shape and exhibits a spring action. Furthermore, since the bearing oil 6 is provided with a damping orifice 10 and the damping oil 7 is provided with a plurality of damping pockets 15 facing each other, the area around the damping pocket 15 is locally displaced and the area around it is filled with fluid. Become. This means that local fluid film squeeze dampers are distributed and arranged in the circumferential direction.

Plain type journal bearings generally have problems with high-speed stability. That is, at more than twice the primary critical speed, self-excited vibrations called whirl occur, leading to an unstable state. This phenomenon is due to the low damping ability of the fluid film and
This is due to a decrease in the amount of eccentricity of the rotating shaft 1 due to the generation of excessive fluid film pressure in the high speed range. The fluid bearing 4 has the function of limiting the generation of this excessive fluid film pressure and effectively utilizing the excess pressure as external damping. This is the damping orifice 10 and damping pocket 1 mentioned above.
5, this is based on the effect that fluid squeeze dampers can be locally distributed and arranged on the damp oil 7 side of the bearing foil 6. This feature allows high-speed stabilization to be achieved. Furthermore, since the combination of the rudder oil 12 and the spring oil 8 has a structure in which the radial spring action is distributed in the circumferential direction, it is possible to cope with centrifugal expansion, thermal deformation, etc. of the rotating shaft 1 due to high-speed rotation. , exhibits even better performance. These functions are due to the use of the foil body 5 made of an elastic thin plate as a component of the bearing 4, and are features that cannot be achieved with a rigid bearing.

Although the above explanation has been made using a plain type journal bearing as an example, the bearing foil 6 can be applied to any dynamic pressure type bearing such as a herringbone type, a step type, a tapered land type, etc., and exhibits excellent functions.

Incidentally, the damping orifice 10 also has a function of discharging foreign matter that has entered the bearing surface to the outside.

[Modified Embodiment] Modified embodiments are shown in FIGS. 5 to 10.

5 and 6, a damping pocket 15 is integrally attached to a damping orifice 10 on the back side of the bearing foil 6 facing the damping oil 7.
was formed.

The configuration shown in FIGS. 7 and 8 is the same as that of the above-mentioned embodiment, but the dump oil 7 and the bearing oil 6 are expanded in width to be equal to the width of the rudder oil 12.

The structure shown in FIGS. 9 and 10 has a damping pocket 15 formed integrally with the damping orifice 10 on the back surface of the bearing oil 6 facing the damp oil 7 in the structure shown in FIGS. 7 and 8. be.

Of course, even in these modified embodiments, the same effects as in the above embodiments can be achieved.

[Effects of the Invention] In summary, the present invention provides the following excellent effects.

(1) Bearing oil, dump oil, and spring oil are formed all at once on an elastic band-shaped oil body,
Since the bearing can be constructed by winding the foil body, the number of parts is small and cylindrical surface molding is easy, improving manufacturability and reducing costs.

(2) Elements that cause errors can be reduced, and the elasticity of the elastic band-shaped foil body can provide a bearing with high precision and high reliability.

[Brief explanation of drawings]

FIG. 1 is a front view showing a state in which the hydrodynamic bearing structure according to the present invention is installed, FIG. 2 is a plan view showing a preferred embodiment of the present invention, FIG. 3 is a side sectional view thereof, and FIG. The figure is an enlarged developed sectional view of part A in FIG. 1, FIGS. 5 to 10 are plan views or side sectional views showing modified embodiments, and FIG. 11 is a perspective view showing a conventional example. In the figure, 1 is a rotating shaft, 3 is a bearing surface, 5 is an elastic band-shaped oil body, 6 is a bearing oil, 7 is a dump oil, 8 is a spring oil, and 9 is a bearing surface.

Claims (1)

[Scope of utility model registration request] In a fluid bearing formed by laminating an elastic foil on a bearing surface and supporting a rotating shaft by fluid film pressure, the bearing foil forms a fluid film on the bearing surface, the bearing foil and the bearing surface. A damp oil provided between the bearing oil for damping the vibration of the bearing oil, and a spring oil for elastically supporting the damp oil on the bearing surface are formed continuously along the longitudinal direction of the elastic band-shaped oil body. and the elastic band-shaped foil body,
A hydrodynamic bearing structure characterized in that these bearing foils, dump oils, and spring foils are formed by rolling them in the longitudinal direction so as to overlap each other in a layered manner.