WO2012127998A1

WO2012127998A1 - Foil bearing and manufacturing method therefor

Info

Publication number: WO2012127998A1
Application number: PCT/JP2012/054912
Authority: WO
Inventors: 和慶原田; 夏比古森; 哲弥栗村; 尾藤　仁彦
Original assignee: Ntn株式会社
Priority date: 2011-03-22
Filing date: 2012-02-28
Publication date: 2012-09-27
Also published as: JP2012197887A

Abstract

A foil bearing (1) is equipped with: a top foil (5) in which a wedge-shaped radial bearing clearance (C) is formed between a shaft member (2) inserted in the inner circumference thereof and the top foil; a back foil (6), which is arranged at the outer circumference of the top foil (5) and elastically supports the top foil (5); and a cylindrical outer member (3), at the inner circumference of which the top foil (5) and the back foil (6) are accommodated. The top foil (5) and the back foil (6) are formed integrally by means of a flexible strip of a thin metal plate. More specifically, a foil member (4), with the top foil (5) and the back foil (6) integrally provided thereon, is interposed between the shaft member (2) and the outer member (3).

Description

Foil bearing and manufacturing method thereof

The present invention relates to a so-called foil bearing in which a flexible thin plate is interposed between a shaft member and a cylindrical outer member in which the shaft member is housed in the inner periphery, and a method for manufacturing the same.

Conventionally, as a bearing for supporting a shaft that rotates at high speed in a high temperature environment, such as a main shaft of a gas turbine or a turbocharger, in addition to an oil-lubricated rolling bearing, a hydrodynamic bearing that is a type of a sliding bearing (fluid hydrodynamic bearing) ) Was used. Air is used as the lubricating fluid, especially when it is difficult to separately provide auxiliary equipment for oil circulation, when shear resistance of lubricating oil becomes a problem, or when contamination of the surrounding environment due to oil becomes a problem. An air dynamic pressure bearing was suitably used.

¡General dynamic pressure bearings are composed of rigid surfaces on both the rotating and stationary sides. In this type of hydrodynamic bearing, if the clearance width management of the radial bearing gap formed between the bearing surface on the rotating side and the stationary side is insufficient, self-excited, called a whirl when the stability limit is exceeded This makes it easy for the main spindle to swing. Therefore, in general dynamic pressure bearings, it is necessary to manage the gap width of the radial bearing gap with high precision (maintain within the proper range at all times) in order to stably exhibit and maintain the desired bearing performance. .

By the way, as described in, for example, Patent Document 1 below, heat resistance of 300 ° C. or higher is generally required for the above-described support bearings of the gas turbine and the supercharger. However, when a hydrodynamic bearing is used in an environment of high temperature, the radial width of the radial bearing gap is likely to fluctuate due to the effect of thermal expansion, and it is difficult to stably maintain desired bearing performance. Therefore, a bearing called a foil bearing has been proposed or put into practical use. A foil bearing comprises a bearing surface made of a thin plate (thin film) having low rigidity with respect to bending, and supports the load by allowing deflection of the bearing surface. For example, the following patent document What is disclosed in 2 and 3 is known.

Specifically, a top foil that forms a wedge-shaped radial bearing gap between the shaft member inserted in the inner periphery, a back foil that is disposed on the outer diameter side of the top foil and elastically supports the top foil, and a top And a cylindrical outer member in which a foil and a back foil are accommodated in the inner periphery. In such a foil bearing, when the shaft member rotates (eccentric rotation), a wedge-shaped radial bearing gap is formed between the outer peripheral surface of the shaft member and the inner surface of the top foil, and this radial bearing gap is formed. The shaft member is supported by the fluid film so as to be relatively rotatable in the radial direction. During rotation of the shaft member, the top foil and the back foil are elastically deformed according to the pressure distribution variation in the radial bearing gap, so the gap width of the radial bearing gap is automatically adjusted (always maintained within an appropriate range). The Further, the vibration of the shaft / bearing system is suppressed (damped) by the frictional force acting on the top foil as the top foil and the back foil are elastically deformed. Therefore, the foil bearing is excellent in stability and can be used at a higher speed than a general dynamic pressure bearing.

In addition, since the radial bearing clearance of a general dynamic pressure bearing needs to be managed on the order of 1/1000 of the shaft diameter, for example, when supporting a shaft having a diameter of about several millimeters, the clearance width of the radial bearing clearance Must be controlled to about several μm. Therefore, in consideration of manufacturing tolerances and thermal expansion, it must be said that it is extremely difficult to strictly manage the gap width with a general dynamic pressure bearing. On the other hand, in the case of a foil bearing, since the gap width is automatically adjusted by elastic deformation of the top foil itself that forms the radial bearing gap, if the gap width of the radial bearing gap is controlled to about several tens of μm. It ’s enough. Therefore, the foil bearing has an advantage that manufacturing and clearance width management can be facilitated as compared with a general dynamic pressure bearing.

In addition, the foil bearing of patent document 2 rolls a flexible strip | belt-shaped metal thin plate in a cylinder shape by the round-up part provided in the back foil formed by rolling a strip | belt-shaped thin metal plate which has flexibility in a cylinder shape. The top foil formed is elastically supported. Moreover, the foil bearing of patent document 3 has a top foil which rolls a strip | belt-shaped metal thin plate into a cylinder shape by the bending part provided in the back foil formed by rolling a strip | belt-shaped metal thin plate which has flexibility in a cylinder shape. The structure is elastically supported.

Japanese Patent No. 26669419 JP 2002-364463 A JP 2009-299748 A

In the foil bearings described in

Patent Documents

2 and 3, the top foil and the back foil that elastically supports the top foil are individually manufactured and accommodated (fixed) on the inner periphery of the outer member. For this reason, the manufacturing process and component management are likely to be complicated, and this is one of the causes for increasing the cost of foil bearings.

Therefore, an object of the present invention is to enable mass production of foil bearings at low cost.

The foil bearing according to the present invention, which was created to achieve the above object, is arranged on the outer diameter side of the top foil that forms a wedge-shaped radial bearing gap between the shaft member inserted in the inner periphery and the top foil. A back foil that elastically supports the top foil, and a cylindrical outer member that accommodates the top foil and the back foil in the inner periphery, and the shaft member and the outer member are formed by a fluid film generated in the radial bearing gap. The top foil and the back foil are integrally formed of a strip-shaped thin plate having flexibility.

In this way, if the top foil and the back foil are integrally formed, the manufacturing process and parts management are simplified by the fact that the number of substantial parts is reduced compared to the conventional product in which the top foil and the back foil are separately provided. can do. Thereby, cost reduction of a foil bearing can be achieved. In addition, since a strip-shaped thin plate having flexibility is used as a material for forming an integrally formed product of the top foil and the back foil (hereinafter also referred to as “foil member”), various functions required for the foil bearing, for example, radial The adjustment function of the gap width of the bearing gap can be appropriately ensured. As the thin plate, a metal, a resin, a ceramic, or a laminate of two or more selected from these can be used, and can be appropriately selected according to required characteristics.

The foil member is formed by forming a folded portion by folding the thin plate at a predetermined position in the longitudinal direction, and rolling the thin plate including the folded portion into a cylindrical shape along the longitudinal direction. be able to. If it does in this way, in addition to being able to form a foil member easily, it becomes possible to slide a top foil and a back foil mutually in the peripheral direction. If the top foil and the back foil can slide relative to each other in the circumferential direction, the vibration generated during the operation of the foil bearing can be damped by the sliding of both, so that the shaft member can be stably supported. It will be advantageous.

The back foil may have a concavo-convex shape portion formed by molding, and the top foil can be elastically supported by the concavo-convex shape portion. If the concavo-convex shape part is molded, after the cut is formed in the thin plate, the peripheral edge of the cut is raised (Patent Document 2) or the thin plate is bent in a complicated manner (Patent Document 3). The elastic support portion can be formed easily and accurately as compared with the case where the portion (elastic support portion) for supporting the structure is formed.

A plurality of uneven portions can be provided in the radial direction, and two uneven portions adjacent in the radial direction can be slid relative to each other. If it does in this way, in addition to improving the load capacity of radial load, the damping effect of vibration can be raised further. Such a configuration can be obtained, for example, by providing a plurality of the folded portions in the radial direction and providing a concavo-convex shape portion in each of the two folded portions adjacent in the radial direction (see FIG. 2 and the like). .

When the foil member is removed from the inner periphery of the outer member, the foil bearing does not perform its function. Therefore, the foil member needs to be fixed to the inner periphery of the outer member. However, if the foil member can be prevented from being removed from the inner periphery of the outer member as much as possible during the operation of the foil bearing, there is a special limitation on the method of fixing the foil member to the outer member. There is no. For example, the foil member can be fixed to the outer member by means such as press-fitting, adhesion, press-fitting adhesion (combination of press-fitting and adhesion), and welding. In addition, instead of each fixing means described above, or in addition to each fixing means described above, a so-called irregularity is formed by fitting a convex portion provided on the other side into a concave portion provided on one of the foil member and the outer member. The foil member can be fixed to the inner periphery of the outer member by fitting. When the above-described uneven shape portion is provided on the back foil, the foil member can be fixed to the outer member by the uneven fitting using the uneven shape portion.

In addition, a radial protrusion is provided at the axial end of the back foil (whether it is one end or both ends), and this protrusion is connected to the end surface of the outer member and the shaft of the outer member. It may be configured to be clamped and fixed in the axial direction with a clamping member provided on the outer side in the direction, or provided with a protruding portion in the radial direction at both axial ends of the back foil, and the protruding portion on one axial end side and the other axial end The outer member may be held in the axial direction by the protruding portion on the side. In this way, if the back foil (foil member) is fixed to the outer member by using the protruding portion provided at the axial end of the back foil, the foil member is moved outward by means of adhesion or welding. As compared with the case of fixing to the member, the assembly of the foil member to the outer member can be performed easily.

In the case of adopting any of the fixing means described above, the back foil can be completely fixed to the outer member (both are firmly fixed so that relative movement of the foil member with respect to the outer member is not allowed), The back foil can be fixed to the outer member in a state in which at least a part of the surface of the back foil facing the outer member is slidable with the outer member. By adopting the latter configuration, it is possible to enhance the damping effect of vibrations generated during the operation of the foil bearing.

Between the back foil and the outer member, a cylindrical spacer portion integrally formed with the top foil and the back foil so as to be slidable with the back foil can be interposed. By doing so, it is possible to further enhance the damping effect of vibration generated during the operation of the foil bearing, as the frictional force generated in the foil member during the rotation of the shaft member is further increased. Moreover, since the spacer portion is integrally formed with the back foil, the labor required for assembly and component management does not increase.

When the spacer portion is provided, a radial protrusion is provided at the axial end (whether it is one end or both ends) of the spacer, and this protrusion is connected to the outer member and the outer member. By holding and fixing in the axial direction with a clamping member arranged on the outer side in the axial direction of the lateral member, or by providing radial protruding portions at both axial ends of the spacer portion, the protruding portion on one axial end side and the axial direction The foil member can be fixed to the outer member by sandwiching the outer member in the axial direction with the protruding portion on the other end side.

By the way, a strip-shaped thin plate that becomes a top foil and a back foil (and, in some cases, includes a spacer portion) can be obtained by cutting a raw roll into a predetermined dimension, for example. The part (edge) becomes a cut surface. In some cases, a sharp protrusion such as a burr may be formed on the cut surface. Therefore, if the shaft member contacts the axial end of the top foil due to misalignment or the like during the operation of the foil bearing, the shaft Scratches or the like may be formed on the outer peripheral surface of the member, which may adversely affect the rotation accuracy. Such a problem can be prevented as much as possible, for example, by providing a relief portion that recedes to the outer diameter side of the axial center region of the top foil in the axial end region of the top foil.

The foil bearing according to the present invention described above can be preferably used for supporting a rotor of a gas turbine, a rotor of a supercharger, or the like.

The foil bearing according to the present invention described above forms a folded portion by folding a strip-shaped thin plate having flexibility at a predetermined position in the longitudinal direction, and the thin plate including the folded portion is arranged along the longitudinal direction. And by rounding it into a cylindrical shape, it is obtained through a manufacturing process having a process of manufacturing an integrally formed product of a top foil and a back foil and a process of arranging the integrated product on the inner periphery of an outer member. Can do.

Alternatively, in the foil bearing according to the present invention, the remaining portion of the thin plate is gradually formed on the inner periphery of the outer member while one end in the longitudinal direction of the flexible strip-shaped thin plate is disposed on the inner periphery of the outer member. At least the step of rounding the remaining portion of the thin plate along the inner peripheral surface of the outer member while forming the folded portion, forming the folded portion by folding the remaining portion of the thin plate at a predetermined position in the longitudinal direction, and removing the folded portion. It can also be obtained by performing a step of rounding along the inner peripheral surface of the rectangular member.

In any of the above-described manufacturing methods (manufacturing procedures), it is desirable to use a flexible strip-shaped thin plate having a concavo-convex shape portion formed in a predetermined region in the longitudinal direction.

As described above, according to the present invention, the mass production cost of the foil bearing can be reduced.

It is a top view of the foil bearing which concerns on one Embodiment of this invention. It is a perspective view of the foil member which comprises the foil bearing of FIG. It is a schematic perspective view of the 1st intermediate workpiece which becomes a foil member shown in FIG. FIG. 4 is a schematic perspective view of a second intermediate workpiece formed by folding back the first intermediate workpiece shown in FIG. 3. It is a schematic perspective view of the 1st intermediate workpiece which concerns on a modification. It is a top view of the foil bearing which concerns on other embodiment of this invention. It is a perspective view of the foil member which comprises the foil bearing of FIG. It is a schematic perspective view of the 1st intermediate workpiece which becomes a foil member shown in FIG. It is a modification of the foil member shown in FIG. It is a schematic sectional drawing of the foil bearing incorporating the foil member shown in FIG. It is a top view of the foil bearing which concerns on other embodiment of this invention. It is a figure which shows notionally the modification of the foil bearing which concerns on this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a plan view of a foil bearing 1 according to an embodiment of the present invention. A foil bearing 1 shown in FIG. 1 is for rotatably supporting a shaft member 2 that rotates at high speed in a high temperature environment, such as a rotor of a gas turbine or a rotor of a supercharger. A foil member 4 in which the shaft member 2 is inserted in the inner periphery and a cylindrical outer member 3 in which the foil member 4 is accommodated in the inner periphery are provided as main constituent members. The outer peripheral surface of the shaft member 2 is formed as a smooth cylindrical surface without unevenness.

The outer member 3 is formed in an endless cylindrical shape in the circumferential direction by a solid (non-porous) metal material or resin material, and is fixed to the inner periphery of a stationary side member (not shown).

As shown in FIG. 2, the foil member 4 is formed in a flat surface shape with no irregularities, and a wedge-shaped radial bearing gap C is formed between the outer peripheral surface 2 a of the shaft member 2 inserted in the inner periphery. The substantially cylindrical top foil 5 and the substantially cylindrical back foil 6 disposed on the outer diameter side of the top foil 5 and elastically supporting the top foil 5 are integrally formed. It is formed in a cylindrical shape with ends in the direction. The back foil 6 has one end portion in the circumferential direction connected to the circumferential end portion of the top foil 5, and a substantially cylindrical first folded portion 7 provided with a concavo-convex shape portion A1 over substantially the entire region, and a circumferential direction One end portion is connected to the other end portion in the circumferential direction of the first folded portion 7, and includes a substantially cylindrical second folded portion 8 provided with a concavo-convex shape portion A 2 over substantially the entire region. The concave and convex portions A1 and A2 function as elastic support portions for elastically supporting the top foil 5, and relative sliding in the circumferential direction between the first folded portion 7 and the second folded portion 8 is performed. They are engaged with each other while allowing movement.

Note that the rotation direction of the shaft member 2 is a direction in which the gap width of the circumferential gap between the one circumferential end of the top foil 5 and the other circumferential end is increased. That is, in the example shown in FIG. 1, the shaft member 2 rotates clockwise. Further, the actual radial bearing gap C has a minute gap width of about several tens of μm, but is exaggerated in FIG. 1 for easy understanding. The same applies to plan views (FIGS. 6 and 12) of a foil bearing 1 according to another embodiment to be described later.

The foil member 4 having the above configuration can be manufactured, for example, as follows.

First, a flexible thin metal sheet unwound from a raw roll (not shown) is cut into a predetermined size to obtain a strip-shaped (long) thin metal sheet to be processed into the foil member 4. Next, by pressing the strip-shaped metal thin plate cut to a predetermined size, the concave / convex shape portion A2 is formed in one end region in the longitudinal direction of the thin metal plate, and the concave / convex shape portion in the substantially central region in the longitudinal direction of the thin metal plate. A1 is molded. As a result, as shown in FIG. 3, the concave and convex portions A2 and A1 are respectively molded in one end region and the substantially central region in the longitudinal direction, and a flat surface portion 5 ′ having no irregularities is provided in the other end region in the longitudinal direction. The obtained first intermediate processed body 14 is obtained. In FIG. 3, the concavo-convex shape portion A1 is obtained by forming concave portions recessed downward in the drawing at predetermined intervals in the longitudinal direction of the metal thin plate, and the concavo-convex shape portion A2 is retracted upward in the drawing. It is obtained by forming the recesses at predetermined intervals in the longitudinal direction of the thin metal plate.

Thereafter, in the first intermediate processed body 14, the formation region of the concavo-convex shape portion A 2 is folded counterclockwise with the fold line T between the concavo-convex shape portions A 1 and A 2 as a fulcrum, and the formation region of the concavo-convex shape portion A 1. Then, the folding line T between the concavo-convex shape portion A1 and the flat surface portion 5 ′ is turned around clockwise as a fulcrum (see the white arrow in FIG. 3 for the turning direction). Thereby, as shown in FIG. 4, the flat surface portion 5 ′, the first folded portion 7 having the molded uneven portion A1, and the second folded portion 8 having the molded uneven portion A2 are successively connected. And the 2nd intermediate processed body 15 of the three-layer structure laminated | stacked in order is obtained. Then, the flat surface portion 5 ′ side is set as the inner diameter side so that the one end portion and the other end portion in the longitudinal direction of the second intermediate workpiece 15 are arranged close to each other in the circumferential direction. Round the longitudinal direction of the thin plate along the contour shape. Thereby, the foil member 4 which makes the end-shaped cylindrical shape in the circumferential direction is obtained.

The foil member 4 is accommodated and fixed to the inner periphery of the outer member 3. Here, the outer diameter surface of the foil member 4 (back foil 6) is lightly press-fitted into the inner periphery of the outer member 3 (press-fitted with a tightening allowance that allows relative movement of the foil member 4 with respect to the outer member 3). Thus, the foil member 4 is fixed to the inner periphery of the outer member 3. In the state where the foil member 4 is fixed to the inner periphery of the outer member 3, the top foil 5 and the first folded portion 7 of the back foil 6 are slidably in contact with each other, and the first folded portion The concavo-convex shape portion A1 provided on the foldable portion 7 and the concavo-convex shape portion A2 provided on the second folded portion 8 are also in slidable contact. And after fixing the foil member 4 to the inner periphery of the outer member 3 in this aspect, the foil bearing 1 shown in FIG. 1 is obtained by inserting the shaft member 2 into the inner periphery of the foil member 4.

In the above, the foil bearing 1 (the assembly of the outer member 3 and the foil member 4 shown in FIG. 1) is secured by fixing the foil member 4 (second intermediate processed body 15) manufactured in advance to the inner periphery of the outer member 3. However, the procedure for obtaining the foil bearing 1 shown in FIG. 1 is not limited to the above.

That is, although illustration is omitted, the foil member 4 is assembled to the outer member 3 while the foil member 4 is manufactured from the first intermediate processed body 14 including the flat surface portion 5 ′ and the uneven shape portions A1 and A2. Is also possible. An example of the specific procedure is shown below.

In the state where one end in the longitudinal direction of the first intermediate workpiece 14 (here, the end on the uneven shape portion A2 side) is disposed and fixed on the inner periphery of the outer member 3, the remaining portion of the first intermediate workpiece 14 ( The second folded portion 8 constituting the back foil 6 is formed by rolling the uneven shape portion A2 along the inner peripheral surface of the outer member 3 while gradually inserting the uneven shape portion A2) into the inner periphery of the outer member 3. Form. After the second folded portion 8 is formed, the concavo-convex shape portion A1 is formed using the fold line T as a fulcrum while gradually inserting the remaining portion (the concavo-convex shape portion A1) of the first intermediate processed body 14 into the inner periphery of the outer member 3. The folded portion (first folded portion 7) is formed by folding back to the inner diameter side, and the first folded portion 7 is rounded along the inner peripheral surface of the outer member 3. Thereby, the back foil 6 which consists of the 1st and 2nd folding | turning

parts

7 and 8 among the foil members 4 is formed. Further, while gradually inserting the remaining portion (flat surface portion 5 ′) of the first intermediate workpiece 14 into the inner periphery of the outer member 3, the flat surface portion 5 ′ is folded back to the inner diameter side with the fold line T as a fulcrum, thereby turning the folded portion back. The top foil 5 is formed by rolling it along the inner peripheral surface of the outer member 3. Thereby, the assembly of the foil member 4 to the outer member 3 is completed at the same time that the foil member 4 shown in FIGS. 1 and 2 is completed.

In the above procedure, the outermost diameter portion (second folded portion 8 of the back foil 6) of the foil member 4 is formed with priority, but the innermost diameter portion (top foil 5) of the foil member 4 is prioritized. It is also possible to follow the procedure to form. Further, such a manufacturing procedure can be similarly adopted in other embodiments described later.

In the foil bearing 1 having the above configuration, when the shaft member 2 rotates (eccentric rotation), a wedge-shaped radial bearing gap C is formed between the outer peripheral surface 2a of the shaft member 2 and the inner diameter surface 5a of the top foil 5. The shaft member 2 is supported in a non-contact manner so as to be rotatable in the radial direction by the air film formed in the radial bearing gap C. During the rotation of the shaft member 2, the flexibility of the top foil 5 allows the top foil 5 to be arbitrarily selected according to changes in the load acting on the top foil 5, the rotation speed of the shaft member 2, the ambient temperature, and the like. Therefore, the gap width of the radial bearing gap C is automatically adjusted to an appropriate width according to the operating conditions. By such a function of automatically adjusting the gap width, the rotation of the shaft member 2 is stably supported.

Further, the top foil 5 is elastically supported by the concavo-convex shape portions A 1 and A 2 provided on the first and second folded

portions

7 and 8 of the back foil 6, and the foil member 4 is disposed inside the outer member 3. The self-adjustment ability of the radial width of the radial bearing gap C is strengthened for the reason that the foil member 4 is lightly press-fitted around the periphery and the foil member 4 is slidable with respect to the outer member 3. Vibration generated with rotation can be effectively damped. In particular, in the present embodiment, two concavo-convex portions that function as elastic support portions of the top foil 5 are provided in the radial direction, and the two concavo-convex portions A1, A2 (first and second folded portions 7, 8) are provided. Are fitted so as to be slidable in the circumferential direction, it is possible to effectively enhance the load capacity of the radial load and the vibration damping effect. Therefore, the radial width of the radial bearing gap C can be managed within an appropriate range even under severe operating conditions such as high temperature and high speed rotation, and the rotation of the shaft member 2 is supported more stably.

In the foil bearing 1 according to the present invention, the foil member 4 which is an integrally formed product of the top foil 5 and the back foil 6 is interposed between the shaft member 2 and the outer member 3, so that the top foil and the back foil Compared with the conventional foil bearing in which the foil is provided individually, the number of parts is substantially reduced. For this reason, the manufacturing process and parts management can be simplified, and the mass production cost of the foil bearing 1 can be reduced. Moreover, since such a foil member 4 is formed of a flexible strip-shaped metal thin plate, as described above, various functions required for the foil bearing 1 (automatic adjustment function of the gap width of the radial bearing gap C). Etc.) can be secured appropriately. Moreover, the folded

members

7 and 8 are formed by folding the thin metal plate at a predetermined position in the longitudinal direction of the foil member 4, and the thin metal plate including the folded

portions

7 and 8 is formed in a cylindrical shape along the longitudinal direction. Since it was formed by rolling, the desired foil member 4 can be easily formed. In addition, since the concavo-convex shape portions A1 and A2 that function as elastic support portions are molded by press working, there is an advantage that the elastic support portions can be easily and accurately formed as compared with conventional products.

In the foil bearing 1 described above, the foil member 4 in which the top foil 5 and the back foil 6 having two uneven portions in the radial direction are integrally formed is used. However, the foil member 4 has the uneven portion. Only one may be provided in the radial direction. Such a foil member 4 can be obtained by using, for example, a first intermediate processed body 14 (see FIG. 5) including a flat surface portion 5 ′ and an uneven shape portion A 1. As described above, the configuration in which only one uneven portion is provided in the radial direction, that is, the configuration in which the back foil 6 has a single layer structure can be similarly applied to other embodiments described below. Although not shown, three or more concavo-convex portions can be provided in the radial direction (the back foil 6 has a multilayer structure of three or more layers).

FIG. 6 shows a foil bearing 1 according to another embodiment of the present invention. The main difference of the foil bearing 1 shown in FIG. 1 from that shown in FIG. 1 is that it is formed integrally with the back foil 6 between the back foil 6 and the outer member 3 so as to be slidable with respect to the back foil 6. The point is that a substantially cylindrical spacer 9 is interposed. Such a configuration can be obtained by using the foil member 4 having a substantially cylindrical spacer portion 9 connected to the outside of the second folded portion 8 as shown in FIG. The spacer portion 9 is formed in a flat surface shape with no unevenness in the entire region. Since other configurations are substantially the same as those described above, common reference numerals are assigned and redundant descriptions are omitted.

As shown in FIG. 8, the foil member 4 shown in FIG. 7 includes a flat surface portion 5 ′, a concavo-convex shape portion A 1, a concavo-convex shape portion A 2, and a flat surface portion without undulations from one end side to the other end side in the longitudinal direction. 9 'can be obtained from the strip-shaped first intermediate processed body 14 provided in order. That is, in the first intermediate processed body 14 shown in FIG. 8, the concave-convex shape portion A1, the concave-convex shape portion A2, and the flat surface portion 9 ′ are folded back in the direction indicated by the white arrow in the same figure, and the four-layer structure second intermediate processing is performed. Forming a body (not shown), and the second intermediate working body with the flat surface portion 5 'side as the inner diameter side so that one end and the other end in the longitudinal direction of the second intermediate working body are arranged close to each other in the circumferential direction. If the body is rounded in the longitudinal direction, a cylindrical member 7 with end ends shown in FIGS.

Thus, if the spacer part 9 slidable with respect to the back foil 6 is further provided, the friction force generated in the foil member 4 during the rotation of the shaft member 2 can be further increased. The damping effect of vibration generated during the operation is further enhanced, and the shaft member 2 can be supported more stably. In addition, since the spacer portion 9 is integrally formed with the top foil 5 and the back foil 6, the labor required for assembly and component management is not increased.

In the foil bearing 1 described above, light press-fit is adopted as a fixing means for the foil member 4 with respect to the outer member 3 in order to improve the damping effect of vibration generated during operation. The same can be obtained when a partial region in the circumferential direction of the foil member 4 is fixed to the inner periphery of the outer member 3 by means such as adhesion or welding. If the vibration damping effect is sufficiently secured, the foil member 4 and the outer member 3 may be firmly fixed so that relative sliding movement is not allowed.

Although not shown, a so-called convex portion provided on the other is fitted into a concave portion provided on one of the inner peripheral surface of the outer member 3 and the outer diameter surface of the foil member 4 facing each other. The foil member 4 can also be fixed to the inner periphery of the outer member 3 by uneven fitting. In addition, when the outer diameter surface of the foil member 4 is configured by a concavo-convex shape portion as in the above-described embodiment, the foil member 4 is connected to the inner periphery of the outer member 3 by concavo-convex fitting using the concavo-convex shape portion. Can be fixed to. This uneven fitting can be additionally employed even when the foil member 4 is completely fixed to the inner periphery of the outer member 3 by means such as adhesion, press-fitting, press-fitting adhesion, or welding.

The method for fixing the foil member 4 to the outer member 3 is not limited to the above as long as the foil member 4 can be prevented from being pulled out from the inner periphery of the outer member 3 as much as possible. .

For example, a radial projecting portion 10 is provided at an axial end portion of the foil member 4 (whether it is one end portion or both end portions), and the foil member 4 is attached to the outer member using the projecting portion 10. 3 can also be fixed. FIG. 9 shows a case in which the protrusions 10 are provided on the foil member 4 (see FIGS. 6 and 7) whose outermost diameter portion is constituted by the spacer portion 9. A radial protrusion 10 is provided. Thus, when the radial protrusion 10 is provided at the axial end of the foil member 4, the protrusion 10 is connected to the end surface of the outer member 3 and the axially outer side of the outer member as shown in FIG. 10. And can be clamped and fixed by a cylindrical clamping member 11 provided in the cylinder. In FIG. 9, the radial protrusions 10 are provided at only one place in the circumferential direction. However, the protrusions 10 may be provided at a plurality of places in the circumferential direction or may be provided over the entire circumference. (It may be formed in a substantially annular shape). Although not shown in the drawings, this configuration is shown in FIG. 1 and other foil bearings 1 (the outermost diameter portion includes a second folded portion 8 having a concavo-convex shape portion A2, that is, a foil member 4 constituted by a back foil 6. Of course, it is also possible to apply to the above.

If such an attachment structure is employed, the assembly process is simplified as compared with the case where the foil member 4 is fixed to the outer member 3 by means such as adhesion or welding, and the foil member starts from the inner periphery of the outer member 3. It is possible to effectively prevent 4 from being pulled out. In this case, the protrusion 10 may be clamped with a force that allows relative sliding movement between the outer member 3 and the foil member 4, or the relative relationship between the outer member 3 and the foil member 4. It is also possible to hold the sheet firmly so that sliding movement is not allowed.

Further, for example, radial protrusions 10 are provided at both axial ends of the foil member 4, and the outer member 3 is axially moved by the protrusion 10 on one axial end side and the protrusion 10 on the other axial end side. You may make it pinch. FIG. 11 shows an example of a configuration of a foil bearing 1 to which such a configuration is applied. Radial protrusions 10 are provided at three circumferential positions at both axial ends of the foil member 4 shown in FIGS. 1 and 2. The outer member 3 is sandwiched in the axial direction by the protruding portion 10 on one end side in the axial direction and the protruding portion 10 on the other end side in the axial direction. If such a structure is adopted, the assembly process is simplified as compared to the case where the foil member 4 is fixed to the outer member 3 by means such as adhesion or welding as in the structure shown in FIG. It is possible to effectively prevent the foil member 4 from being removed from the inner periphery of the member 3. In addition, although illustration is abbreviate | omitted, of course, it is also possible to apply this structure to the foil bearing 1 shown in FIG. In this case, the radial protrusions 10 can also be provided at both axial ends of the spacer portion 9 constituting the outermost diameter portion of the foil member 4.

By the way, in the foil bearing 1 described above in which the top foil 5 and the back foil 6 (and, in some cases, the spacer portion 9) are integrally formed of a strip-shaped metal thin plate, the strip-shaped metal thin plate is, for example, as described above. Although it can obtain by cut | disconnecting a non-roll to a predetermined dimension, in this case, the edge part (edge) of a metal thin plate becomes a cut surface. In some cases, a sharp protrusion such as a burr is formed on the cut surface, and when this protrusion comes into contact with the shaft member 2 due to misalignment or the like during the operation of the foil bearing, the protrusion is formed on the outer peripheral surface of the shaft member 2. There is a possibility that scratches and the like are formed and the rotation accuracy is adversely affected. For example, as shown conceptually in FIG. 12, such a problem is that a relief portion 12 that is receded to the outer diameter side from the axial central region of the top foil 5 is provided in the axial end region of the top foil 5. Can be prevented as much as possible. The escape portion 12 can be formed by bending the axial end region of the top foil 5 as shown in the illustrated example, or can be formed by bending (bending) the axial end region of the top foil 5. You can also.

In the above, the foil member 4 in which the top foil 5 and the back foil 6 are integrally provided is obtained by performing appropriate processing on the flexible strip-shaped metal thin plate. 4 can also be obtained from a strip-shaped resin thin plate having flexibility, a ceramic thin plate, or a thin plate obtained by laminating two or more selected from the group of metals, resins and ceramics.

However, when the foil member 4 is obtained from a resin thin plate or a laminated thin plate including a resin layer, it is necessary to select an appropriate base resin particularly from the viewpoint of heat resistance. That is, as the base resin constituting the thin plate, for example, general-purpose plastics such as polyethylene (PE) and polypropylene (PP), engineering plastics such as polyacetal (POM), polybutylene terephthalate (PBT), and polyethylene terephthalate (PET), and A mixture of one or more selected from super engineering plastics such as polyphenylene sulfide (PPS) and polyether ether ketone (PEEK) can be used, but the foil bearing 1 has a high temperature of about 300 ° C. as described above. Considering use in the environment, super engineering plastics with particularly high heat resistance (melting point 300 ° C. or higher) and mechanical strength, specifically polyetheretherketone PEEK) and thermosetting polyimide is preferably based resin. One or more kinds of various fillers such as a reinforcing material, a lubricant, a conductive material, and a dimension stabilizing material can be blended in the base resin.

In the foil bearing 1 described above, the shaft member 2 is the rotating side, and the outer member 3 and the foil member 4 (the top foil 5 and the back foil 6) are the stationary side. Can be preferably applied to the foil bearing 1 in which the outer side 3 and the outer member 3 and the foil member 4 are the rotation side. However, since the foil member 4 is on the rotating side, it is necessary to design both members in consideration of the deformation of the top foil 5 and the back foil 6 due to centrifugal force.

Further, as described above, the present invention can be preferably applied not only to the foil bearing 1 using air as the pressure generating fluid but also to the foil bearing 1 using lubricating oil as the pressure generating fluid.

DESCRIPTION OF SYMBOLS 1 Foil bearing 2 Shaft member 3 Outer member 4 Foil member 5 Top foil 6 Back foil 7 1st folding | turning part 8 2nd folding | turning part 9 Spacer part 10 Protrusion part 11 Clamping member 12 Escape part 14 1st intermediate workpiece 15 2nd Intermediate workpiece A1 Concavity and convexity portion A2 Concavity and convexity portion C Radial bearing clearance

Claims

A top foil that forms a wedge-shaped radial bearing gap between the shaft member inserted in the inner periphery, a back foil that is disposed on the outer diameter side of the top foil and elastically supports the top foil, and the top foil and the back foil In a foil bearing that includes a cylindrical outer member that is housed in the inner periphery and supports relative rotation of the shaft member and the outer member with a fluid film generated in a radial bearing gap.
A foil bearing in which a top foil and a back foil are integrally formed of a flexible strip-shaped thin plate.
In the integrally formed product of the top foil and the back foil, a folded portion is formed by folding the thin plate at a predetermined position in the longitudinal direction, and the thin plate including the folded portion is rolled into a cylindrical shape along the longitudinal direction. The foil bearing according to claim 1, wherein the foil bearing is formed by:
2. The foil bearing according to claim 1, wherein the back foil has a concavo-convex shape portion formed by molding, and the top foil is elastically supported by the concavo-convex shape portion.
The foil bearing according to claim 3, wherein a plurality of uneven portions are provided in the radial direction, and two adjacent uneven portions are slidable in the radial direction.
The radial direction protrusion part is provided in the axial direction edge part of the back foil, This protrusion part is clamped and fixed to the axial direction with the outer member and the clamping member arrange | positioned on the axial direction outer side of an outer member. The foil bearing described.
2. The foil according to claim 1, wherein radial protrusions are provided at both axial ends of the back foil, and the outer member is sandwiched in the axial direction by the protrusions on one axial end side and the protrusions on the other axial end side. bearing.
The foil bearing according to claim 1, wherein a spacer portion integrally formed with the top foil and the back foil is provided between the back foil and the outer member so as to be slidable with the back foil.
A radial projection is provided at the axial end of the spacer portion, and the projection is clamped and fixed in the axial direction by an outer member and a clamping member disposed on the outer side in the axial direction of the outer member. The foil bearing described.
The foil according to claim 7, wherein radial protrusions are provided at both axial ends of the spacer portion, and the outer member is sandwiched in the axial direction by the protruding portion on one end side in the axial direction and the protruding portion on the other end side in the axial direction. bearing.
The foil bearing according to claim 1, wherein a relief portion that recedes to the outer diameter side from the axial central region of the top foil is provided in an axial end region of the top foil.
The foil bearing according to claim 1, which is used for supporting a rotor of a gas turbine.
The foil bearing according to claim 1, which is used for supporting a rotor of a supercharger.
A top foil that forms a wedge-shaped radial bearing gap between the shaft member inserted in the inner periphery, a back foil that is disposed on the outer diameter side of the top foil and elastically supports the top foil, and the top foil and the back foil A cylindrical outer member that is housed in the inner circumference, and a foil bearing manufacturing method that supports relative rotation of the shaft member and the outer member with a fluid film generated in a radial bearing gap.
A flexible strip-shaped thin plate is folded at a predetermined position in the longitudinal direction to form a folded portion, and the thin plate including the folded portion is rounded into a cylindrical shape along the longitudinal direction. And a process for producing a backfoil integrally formed product,
And a step of arranging the integrally formed product on the inner periphery of the outer member.
A top foil that forms a wedge-shaped radial bearing gap between the shaft member inserted in the inner periphery, a back foil that is disposed on the outer diameter side of the top foil and elastically supports the top foil, and the top foil and the back foil A cylindrical outer member that is housed in the inner circumference, and a foil bearing manufacturing method that supports relative rotation of the shaft member and the outer member with a fluid film generated in a radial bearing gap.
At least the remaining portion of the thin plate while gradually inserting the remaining portion of the thin plate into the inner periphery of the outer member with one end in the longitudinal direction of the strip-shaped thin plate having flexibility arranged on the inner periphery of the outer member Rounding along the inner circumferential surface of the outer member, forming the folded portion by folding the remaining portion of the thin plate at a predetermined position in the longitudinal direction, and the folded portion along the inner circumferential surface of the outer member. And a step of rolling the foil bearing.