JP2018165523A - Foil bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foil bearing capable of preventing agglutination of a foil without impairing abrasion resistance on a slide surface of the foil due to peeling of a coat.SOLUTION: A foil bearing 10 includes a foil 12 formed with a protective coat 16, and a foil holder 11 supporting the foil 12, wherein a shaft 13 is supported by a fluid film formed in a bearing interval between the protective coat 16 and the shaft 13. The foil bearing 10 has, on a slide surface side of the foil 12, a chemical conversion coat 15 having an uneven surface 15a formed by chemical conversion, and the protective coat 16 provided on the uneven surface 15a.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a foil bearing.

  As a bearing for supporting a shaft of a turbo machine such as a gas turbine or a turbocharger, a foil bearing has attracted attention. In the foil bearing, a bearing surface is constituted by a thin film (foil) having low rigidity with respect to bending, and the load is supported by allowing the bearing surface to bend. When the shaft rotates, a fluid film (for example, an air film) is formed between the outer peripheral surface of the shaft and the bearing surface of the foil, and the shaft is supported in a non-contact manner. In this case, the flexibility of the foil automatically forms an appropriate bearing gap according to the operating conditions such as the rotational speed, load and ambient temperature of the shaft. It can be used at high speed.

  As the above-mentioned foil bearing, the top foil is elastically supported by cutting and raising provided in the back foil (Patent Document 1), and the bearing foil is elastically supported by an elastic body knitted in a net shape ( Patent Document 2), and a back foil provided with a support portion that contacts the inner surface of the outer ring and does not move in the circumferential direction, and an elastic portion that is elastically bent by the surface pressure from the top foil (Patent Document 3), etc. It is known. Patent Documents 4 and 5 show so-called multi-arc type foil bearings in which a plurality of foils are arranged side by side in the circumferential direction, and both circumferential ends of each foil are attached to an outer member.

  In such a foil bearing, for example, when the shaft is started and stopped, the shaft and the top foil contact and slide. Repeated contact and sliding between the top foil and the shaft may cause adhesion on the sliding surface, resulting in an increase in frictional torque and eventually seizure and breakage of the bearing surface.

  In order to prevent adhesion of the sliding surface, it is common to provide a wear-resistant coating on the sliding surface with the top foil shaft. For example, in Patent Document 6, a fluororesin fired film, a film made of graphite, molybdenum disulfide, or the like is formed on the surface of the top foil to improve the wear resistance of the top foil.

JP 2002-364463 A JP 2003-262222 A JP 2009-299748 A JP 2009-216239 A JP 2006-57828 A JP 2003-56561 A

  As described above, the foil bearing can form an appropriate bearing gap with the shaft by elastically deforming the thin plate-like foil having flexibility during the rotational movement of the shaft. At this time, in the foil bearing configured as in Patent Document 6, the shape of the coating cannot sufficiently follow the deformation of the foil, and the coating peels off from the foil and the wear resistance of the sliding surface is reduced. There is a risk of damage.

  Under such circumstances, an object of the present invention is to provide a foil bearing capable of preventing the foil from adhering without impairing the wear resistance of the sliding surface of the foil due to peeling of the coating or the like.

  In order to solve the above-described problems, the present invention includes a foil having a film formed thereon and a foil holder that supports the foil, and the shaft is formed by a fluid film formed in a bearing gap between the film and the shaft. In the foil bearing to be supported, the coating film is formed on an uneven surface formed by a chemical conversion treatment.

  In the foil bearing of the present invention, by providing a film on the uneven surface formed on the foil, the adhesion between the uneven surface and the film can be improved by increasing the surface area of the contact surface with the film and the anchor effect. Therefore, peeling of the coating can be suppressed, and the effect of improving the wear resistance can be stably brought about on the sliding surface of the foil.

  In addition, even if the film is worn or peeled from the foil, the film component remaining between the uneven surfaces brings a certain wear resistance effect on the sliding surface, It is possible to prevent foil adhesion and wear of the foil itself.

  Furthermore, by forming the concavo-convex surface by chemical conversion treatment, the concavo-convex of a finer and more complicated shape can be formed, and the adhesion of the protective film can be further improved. In addition, it is possible not only to form an uneven surface with a more uniform size than when physically forming an uneven surface, such as polishing using shot blasting or emery paper, but also during processing. No external force needs to be applied to the foil, and the foil does not deform due to the external force.

As the above-mentioned foil bearing, a film containing at least one of PTFE, MoS ₂ and a carbon-based material can be formed. The film having such a structure is particularly likely to be peeled off from the foil, and it is important to improve the adhesion between the foil and the film by forming an uneven surface.

  Further, the present invention provides a foil bearing that includes a foil that forms a bearing surface, and a foil holder that supports the foil, and that supports the shaft with a fluid film formed in a bearing gap between the bearing surface and the shaft. An uneven surface formed by chemical conversion treatment is provided on the bearing surface, and a concave portion of the uneven surface is filled with a filler.

  In the foil bearing of the present invention, the wear resistance of the bearing surface can be improved without providing a wear-resistant film by filling the concave portion of the uneven surface formed in the foil with a filler.

  As said foil bearing, a solid lubricant can be used for a filler.

  As said foil bearing, an uneven surface can be formed in a foil.

  As said foil bearing, an uneven surface can be formed in the chemical conversion film obtained by chemical conversion treatment.

  As described above, in the present invention, the adhesion of the coating film to the foil can be improved by providing the coating film on the uneven surface formed by the chemical conversion treatment. Therefore, the wear resistance is not deteriorated due to peeling of the coating, and the effect of improving the wear resistance stably for a long time can be provided on the sliding surface of the foil.

It is a schematic block diagram of the foil bearing which concerns on embodiment of this invention. It is a top view which shows foil. It is a top view explaining connection of two foils. It is a perspective view explaining connection of three foils. It is a perspective view explaining a mode that a foil is attached to a foil holder. It is sectional drawing explaining a mode that foil is hold | maintained at a foil holder. It is the schematic explaining a mode that the uneven | corrugated surface of the foil which concerns on embodiment of this invention, and a protective film are formed. It is the schematic explaining a mode that the uneven | corrugated surface of the foil which concerns on different embodiment of this invention, and a protective film are formed. It is an enlarged view of an uneven surface in a different embodiment. It is the schematic which shows the sliding surface of the foil in different embodiment.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

  As shown in FIG. 1, the foil bearing 10 includes a foil holder 11 having a cylindrical inner peripheral surface 11a and three foils 12 attached to the inner peripheral surface 11a. The foil bearing 10 is a so-called multi-arc type foil bearing in which three foils 12 are arranged in the circumferential direction on the inner peripheral surface 11a. A shaft 13 is inserted into the foil bearing 10 inside the foil 12 on the inner peripheral surface 11a side. The foil bearing 10 and the shaft 13 constitute a foil bearing device 14. The foil bearing 10 supports the shaft 13 in a relatively rotatable manner with a fluid film formed between a bearing surface X (described later) of the foil 12 and the shaft 13.

  The foil holder 11 is formed of a metal (for example, a steel material) such as a sintered metal or a melted material. In the inner peripheral surface 11a, axial grooves 11b serving as holding portions are formed at a plurality of locations (three locations in the illustrated example) separated in the circumferential direction.

  The foil 12 is formed of a strip-like foil having a thickness of about 20 μm to 200 μm made of a metal having high spring properties and good workability, such as a steel material or a copper alloy. In an air dynamic pressure bearing using air as a fluid film as in the present embodiment, since no lubricating oil exists in the atmosphere, the antirust effect by the oil cannot be expected. Typical examples of steel materials and copper alloys include carbon steel and brass, but general carbon steel is susceptible to corrosion due to rust, and brass may cause cracks due to processing strain (in brass) This tendency increases as the Zn content increases.) Therefore, it is preferable to use a stainless steel or bronze foil as the belt-like foil.

  As shown in FIG. 2, the foil 12 has a first region 12 a and a second region 12 b that are arranged in the circumferential direction of the foil holder 11.

  The first region 12a includes a top foil portion 12a1 having a bearing surface, and an insertion portion 12a2 protruding at one end in the circumferential direction at the upper end, the center, and the lower end in the axial direction. A minute circumferential notch 12a3 is provided at a position close to the insertion portion 12a2.

  The second region 12b is provided with a protruding portion 12b1 as an under-foil portion, which is three protruding portions whose axial width is gradually narrowed toward the other end in the circumferential direction. The protrusions 12b1 are provided at the upper end, the center, and the lower end in the axial direction, respectively, and a notch 12b2 formed in a substantially arc shape is provided between the protrusions 12b1. In addition, the cutout portion 12b2 may have a substantially V shape in which a straight line is bent at the center of each protruding portion 12b1.

  As shown in FIG. 1, in the foil bearing 10, the top foil portion 12 a 1 is disposed on the shaft 13 side, and the inner peripheral surface thereof forms a bearing surface X. And underfoil part 12b1 is arranged at the foil holder 11 side, and gives elasticity to top foil part 12a1 by overlapping with top foil part 12a1 of other foil 12 adjacent.

  As shown in FIG. 2, at the boundary between the first region 12 a and the second region 12 b, the insertion ports 12 c 1, 12 c 2, and 12 c 1 into which the insertion portions 12 a 2 of the adjacent foil 12 are inserted are respectively the upper end in the axial direction, the center, Provided at the lower end. The insertion port 12c1 is a rectangular cutout portion and is provided to reach the axial end of the foil 12. The insertion port 12c2 has a rectangular cutout portion provided at the same position in the circumferential direction as the insertion port 12c1, and a rectangular cutout portion that protrudes toward the other end in the circumferential direction and has a circular arc at the tip. It consists of a notch part whose width is narrower than that. Moreover, the connection part 12c3 which connects both is formed in the boundary of the 1st area | region 12a and the 2nd area | region 12b.

  As shown in FIG. 3, the two foils 12 can be connected by inserting the insertion portions 12a2, 12a2, 12a2 of one foil 12 into the insertion ports 12c1, 12c2, 12c1 of the adjacent foils 12. it can. The foil 12 constitutes a foil overlap portion C that overlaps in the radial direction of the shaft 13 in a state where the foil 12 is assembled to a foil bearing 10 described later.

  Then, as shown in FIG. 4, the three foils 12 can be temporarily assembled by connecting the three foils 12 circumferentially by the method. The foil bearing 10 is assembled by making this temporary assembly into a cylindrical shape and inserting it into the inner periphery of the foil holder 11 in the direction of arrow B2, as shown in FIG. Specifically, while inserting the temporary assembly of the three foils 12 into the inner periphery of the foil holder 11, the insertion portion 12 a 2 of each foil 12 is opened in the axial groove 11 b opened on one end surface of the foil holder 11. Insert from one end in the axial direction. Thus, the three foils 12 are attached to the inner peripheral surface 11a of the foil holder 11 in a state of being arranged in the circumferential direction.

  As shown in FIG. 6, in the state where the three foils 12 are assembled to the foil holder 11, the insertion portion 12 a 2 that is one circumferential end of each foil 12 is held in contact with the foil holder 11. In the example of illustration, the insertion part 12a2 of each foil 12 is distribute | arranged to the back (outside diameter side) of the foil 12 adjacent, respectively. Specifically, the insertion portion 12a2 provided at one end in the circumferential direction of each foil 12 has an axial groove on the inner peripheral surface 11a of the foil holder 11 via the insertion port 12c1 (12c2) of the adjacent foil 12. 11b. On the other hand, the projecting portion 12b1 provided at the other circumferential end of each foil 12 is disposed between the top foil portion 12a1 of the adjacent foil 12 and the inner peripheral surface 11a of the foil holder 11, and the top of the adjacent foil 12 is disposed. The foil part 12a1 is supported from behind, and the underfoil part 12b1 is configured. The adjacent foils 12 are engaged with each other in the circumferential direction so as to stick to each other. Thereby, the top foil part 12a1 of each foil 12 protrudes to the outer diameter side, and is curved into a shape along the inner peripheral surface 11a of the foil holder 11.

  Moreover, in this embodiment, as shown in FIG. 3, the notch part 12b2 is provided in the protrusion part 12b1, and the level | step difference along the notch part 12b2 is formed in the top foil part 12a1 which rides on this. As a result, the fluid flowing along the top foil portion 12a1 flows along the above steps and is collected on the center side in the axial direction, so that the pressure improvement effect is enhanced (see the arrow in FIG. 3).

  At this time, by providing the minute notch 12a3 in the vicinity of the insertion portion 12a2 in one circumferential end portion of the top foil portion 12a1, the rigidity of this portion is lowered. Thereby, the top foil part 12a1 can be easily deformed along the notch part 12b2 of the second region 12b arranged behind the top foil part 12a1.

  When the shaft 13 rotates in the direction of arrow B1 in FIG. 1, the fluid film in the radial bearing gap between the inner diameter surface (bearing surface) of the top foil portion 12a1 of each foil 12 of the foil bearing 10 and the outer peripheral surface of the shaft 13 Pressure is increased. Since the region including the circumferential end of the top foil portion 12a1 (the end portion on the rotation direction leading side) rides on the protruding portion 12b1 of the adjacent foil 12, the bearing surface of the shaft 13 faces the rotation direction leading side. Gradually approach the outer surface. As a result, a radial bearing gap gradually narrowing toward the leading side in the rotational direction is formed between the bearing surface of each foil 12 and the outer peripheral surface of the shaft 13, and fluid is pushed into the narrow side of the radial bearing gap. It is. Thereby, the pressure of the fluid film in the radial bearing gap is increased, and the shaft 13 is supported in a non-contact manner in the radial direction by this pressure.

  By the way, when the shaft 13 is started or stopped, the rotation of the shaft 13 is slowed down and the fluid pressure between the foil bearing 10 and the shaft 13 is lowered, so that the shaft 13 is lowered by gravity, and the shaft 13 13 and the top foil part 12a1 contact (so-called touchdown) occurs. When the shaft 13 and the top foil portion 12a1 are repeatedly contacted and slid, adhesion occurs on the sliding surface, which may increase frictional torque and eventually cause seizure and damage to the bearing surface. Therefore, the top foil portion 12a1 that slides with the shaft 13 (sliding surface of the foil 12 with the shaft 13) is required to have high wear resistance.

Therefore, the above adhesion can be prevented by providing a wear-resistant protective coating (coating) on the surface of the top foil portion 12a1. Examples of protective coatings provided on the surface of the top foil portion 12a1 include hard coatings using chromium plating, nickel plating, DLC, carbon-based materials such as graphite, molybdenum disulfide (MoS ₂ ), tungsten disulfide ( A coating using a solid lubricant having excellent friction characteristics such as WS ₂ ) and PTFE can be employed.

  By providing the protective coating, the wear resistance of the top foil portion 12a1 can be improved, and adhesion on the sliding surface with the shaft 13 can be prevented. However, on the other hand, in the case of a configuration in which such a protective coating is provided, the adhesion of the coating to the top foil portion 12a1 becomes a problem. That is, as described above, the flexible thin plate-like foil 12 is elastically deformed by the pressure of the fluid film generated in the bearing gap, and the foil bearing 10 allows the shaft 13 to be deformed by allowing the bearing surface to bend. Non-contact support. Therefore, when the adhesive force of the protective film to the top foil portion 12a1 is small during elastic deformation of the foil 12, the shape of the protective film cannot sufficiently follow the foil 12, and the protective film peels off from the foil 12. End up. In particular, among the protective films described above, a film using DLC or PTFE has a problem in adhesion to the foil, and such a peeling is likely to occur. Therefore, countermeasures are important.

  From the above, in this embodiment, in order to improve the adhesion of the protective film to the top foil portion 12a1, an uneven surface is formed by chemical conversion treatment, and the protective film is provided in close contact with the uneven surface.

  Specifically, as shown in FIG. 7A, a chemical reaction is caused by reacting a treatment agent on the surface (sliding surface) on the side where the bearing surface is formed among the surfaces of the top foil portion 12 a 1. . Thereby, as shown in FIG.7 (b), the chemical conversion film 15 provided with the uneven surface 15a is formed in the surface of the top foil part 12a1. And as shown in FIG.7 (c), the abrasion-resistant protective coating (coating) 16 mentioned above is provided in the uneven surface 15a.

  Thus, the uneven surface 15a formed by the chemical conversion treatment has a shape in which fine unevenness is provided in a complicated manner on the surface. Then, the protective coating 16 is formed on the uneven surface 15a, so that the protective coating 16 enters the fine unevenness. Thereby, the adhesion degree with respect to the chemical conversion film 15 (top foil part 12a1) of the protective film 16 can be improved according to the increase in the area which the protective film 16 adheres, and an anchor effect.

  As described above, it is possible to make it difficult to peel the protective coating 16 from the top foil portion 12a1. Further, even if a part of the protective coating 16 is peeled off or worn due to repeated use of the foil bearing, the portion of the protective coating 16 that has entered the concave and convex surface 15a remains, and a certain wear resistance effect is obtained. Can be imparted to the sliding surface. Therefore, adhesion of the top foil part 12a1 and the shaft 13 can be prevented over a long period of time.

  As in the present embodiment, an intermediate layer (chemical conversion film 15) is provided between the top foil portion 12a1 and the protective film 16, and the protective film 16 is in close contact with the intermediate layer. This is effective when DLC or PTFE having poor adhesion to the top foil portion 12a1 is used. Further, when DLC is used for the protective coating 16, peeling of the coating is difficult to propagate, and when the protective coating 16 is peeled off, a part of the protective coating 16 can easily remain.

  In the present embodiment, the chemical conversion film 15 can be formed by causing a phosphate or oxalate such as iron phosphate, zinc phosphate, or manganese phosphate to act on the surface of the foil 12. Further, a chromate treatment in which chromate is applied to the surface of the foil 12 to form the chemical conversion film 15 or a black dyeing treatment in which a high temperature and high concentration alkaline solution is applied to the surface of the foil 12 to form the chemical conversion film 15 is used. You can also These methods can be selected as appropriate according to the material used for the foil 12, the roughness of the target uneven surface, and the like. As an example, a chemical conversion treatment using zinc phosphate as a treating agent is used to form a chemical conversion film 15 having a maximum height roughness (Rz) of an uneven surface of 0.5 to 4.0 μm on the surface of the top foil portion 12a1. Can do. In addition, the maximum height roughness of an uneven surface here is the maximum height roughness defined by JISB0601-2001.

  As a method of forming an uneven surface on the surface of the foil 12, by adopting the method of forming a chemical conversion film on the surface of the foil 12 by chemical conversion treatment as described above, the treatment can be performed at a low temperature. The deformation of the foil 12 due to heating can be suppressed. Further, unlike the case where an uneven surface is physically formed on the surface of the foil 12, no external force is applied to the foil 12, so that deformation and distortion of the foil 12 do not occur. Further, as compared with a physical processing method, the uneven surface 15a having a uniform roughness can be formed without causing unevenness of the height of the uneven surface 15a.

  Furthermore, as a method different from the above-described embodiment, a method of removing the chemical conversion film after forming the surface on the bearing surface side of the top foil portion 12a1 on the uneven surface by chemical conversion treatment can be employed. Specifically, first, as shown in FIG. 8A, a chemical conversion treatment is performed on the surface of the top foil portion 12a1. By this chemical conversion treatment, as shown in FIG. 8B, the chemical conversion film 15 is formed on the surface of the top foil portion 12a1, and the unevenness is formed at the interface between the chemical conversion film 15 and the foil 12 by the action of the treatment agent. The Thereafter, as shown in FIG. 8C, the chemical conversion film 15 is chemically removed from the top foil portion 12a1, thereby forming a top foil portion 12a1 having an uneven surface 12d on the surface thereof. And as shown in FIG.8 (d), the protective film 16 is coated on the uneven surface 12d of the top foil part 12a1.

  In the present embodiment, the protective coating 16 can be formed so as to enter the uneven surface 12d of the top foil portion 12a1, and the adhesion of the protective coating 16 to the top foil portion 12a1 can be improved. This embodiment can be employed particularly when a material having good adhesion to the top foil portion 12a1 is used for the protective coating 16, and as in the above-described embodiment, an intermediate for bringing the protective coating 16 into close contact. The foil 12 having the protective coating 16 on the sliding surface can be formed without providing a layer (chemical conversion coating). Therefore, the thickness change of the foil 12 can be reduced as compared with the above-described configuration, and the influence on the flexibility due to the thickness change can be minimized.

  In addition, as in the above-described embodiment, the foil does not deform due to heating or external force during the process, and the uneven surface can be formed with uniform roughness.

  As an example of the method for removing the chemical conversion film, Chemiblast (registered trademark) treatment by Nippon Parkerizing Co., Ltd. can be used. In the chemiblast treatment, an uneven surface is formed on the surface of the foil by the etching action of the treating agent, and then the chemical conversion film formed on the surface of the foil is removed. By this method, the surface roughness of the foil can give a roughness having a maximum height roughness (Rz) of 0.2 to 5.0 μm as an example.

  In FIG. 9, the enlarged view of the uneven | corrugated surface of the foil 12 formed by said chemiblasting is shown. In this embodiment, compared with a normal chemical conversion treatment, a finer and sharper uneven surface can be formed, and the surface area can be increased. Accordingly, the adhesion of the protective coating 16 to the top foil portion 12a1 can be further increased.

  In addition, the present invention is not limited to the configuration in which the protective coating 16 is provided, and a configuration in which the uneven surface is filled with a lubricant (filler) can also be employed. Specifically, as shown in FIG. 10, a heat-resistant solid powder lubricant 17 is filled in the uneven surface 12d of the top foil portion 12a1 formed by the chemical conversion treatment described above.

Examples of the heat-resistant solid lubricant 17 include molybdenum compounds (MoS ₂ , MoO ₃ , molybdate, etc.), tungsten disulfide (WS ₂ ), graphite, boron nitride (BN), metals (Cu, Ag, etc.) Metal oxides (Fe ₂ O ₃ , SnO, ZnO, etc.) can be used.

  By filling the uneven surface 12d with the lubricant 17 described above, it is possible to improve the wear resistance of the sliding surface of the top foil portion 12a1 without providing the protective coating 16, and to prevent adhesion between the foil and the shaft. it can. Further, since the lubricant 17 has heat resistance, excellent lubricity can be imparted to the sliding surface even under a high temperature atmosphere. In order to fill the lubricant 17 in the gaps between the uneven surfaces 12d, the particle size of the lubricant 17 needs to be smaller than the unevenness of the uneven surface 12d. Further, the particle size of the lubricant shown in FIG. 10 is an example, and by selecting the type of lubricant to be used, the method for forming the uneven surface, the method of surface treatment, and the like, the particle size of the lubricant, and The size of the uneven surface can be adjusted.

  In the above description, the case where the lubricant 17 is embedded in the uneven surface 12d of the top foil portion 12a1 has been described as an example, but the uneven surface 15d of the chemical conversion film 15 as in the embodiment shown in FIG. Alternatively, the lubricant 17 may be embedded.

  The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

  Although the case where the radial foil bearing 10 is configured by a multi-arc bearing has been described in the above embodiment, the present invention is not limited thereto, and one end in the circumferential direction of each foil is attached to the inner peripheral surface 11a of the foil holder 11, and A so-called leaf-type radial bearing foil with the other end in the circumferential direction as a free end, or a so-called bump foil-type radial bearing foil with a corrugated back foil arranged on the outer diameter of a cylindrical top foil can be used. Good. Of course, the present invention can be applied to a thrust foil bearing.

  Moreover, although the case where the shaft 13 was a rotation side member and the foil holder 11 was a fixed side member was illustrated in the above embodiment, conversely, the shaft 13 is a fixed side member and the foil holder 11 is the rotation side. Even when it is a member, the configuration of FIG. 1 can be applied as it is. However, in this case, since the foil 12 serves as a rotation side member, it is necessary to design the foil 12 in consideration of deformation of the entire foil 12 due to centrifugal force.

DESCRIPTION OF SYMBOLS 10 Foil bearing 11 Foil holder 11a Inner peripheral surface 11b Axial direction groove | channel (holding part)
12 Foil 12a1 Top foil part 12a2 Insertion part 12b1 Protruding part (underfoil part)
12d Irregular surface 13 Axis 15 Conversion coating 15a Irregular surface 16 Protective coating (coating)
17 Lubricant X Bearing surface

Claims (6)

A foil having a film formed thereon, and a foil holder for supporting the foil;
In a foil bearing that supports the shaft with a fluid film formed in a bearing gap between the coating and the shaft,
A foil bearing, wherein the coating film is formed on an uneven surface formed by chemical conversion treatment. The foil bearing according to claim 1, wherein the coating is formed of at least one of PTFE, MoS ₂ , and a carbon-based material. A foil that forms a bearing surface, and a foil holder that supports the foil;
In a foil bearing that supports the shaft with a fluid film formed in a bearing gap between the bearing surface and the shaft,
The foil bearing is characterized in that an uneven surface formed by chemical conversion treatment is provided on the bearing surface, and a concave portion of the uneven surface is filled with a filler.   The foil bearing according to claim 3, wherein a solid lubricant is used as the filler.   The foil bearing according to any one of claims 1 to 4, wherein the uneven surface is formed on the foil.   The foil bearing of any one of Claim 1 to 4 in which the said uneven surface is formed in the chemical conversion film obtained by the said chemical conversion treatment.

Images