Radial foil bearing

Abstract

A radial foil bearing, which surrounds a rotating shaft and supports the rotating shaft, includes a bearing housing, an insertion hole which is formed in the bearing housing and through which the rotating shaft is inserted, a recessed groove provided in the inner peripheral surface of the insertion hole and recessed toward the radially outer side, a pin hole base end side having an opening formed in the groove and extending to the outer peripheral surface of the bearing housing, a restricting pin that is inserted into the pin hole base end side and that passes through the groove, and a top foil placed in the insertion hole, the groove being formed so as to reach an axial end surface of the bearing housing, a circumferential end part of the top end foil being placed in the groove, and the restricting pin intersecting the inner side surface of the groove at multiple locations.

Description

Technical Field

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[0001] The present disclosure relates to a radial foil bearing.

Background Art

[0002] Conventionally, as a technique in such a field, a radial foil bearing described in Patent Document 1 below is known. In this radial foil bearing, an insertion hole for inserting a rotating shaft is provided in a bearing case, and a ring foil is installed in a gap between an outer peripheral surface of the rotating shaft and an inner peripheral surface of the insertion hole. A plurality of protrusions protruding axially outward are provided on an outer peripheral surface of the ring foil, and a plurality of grooves into which the protrusions are respectively fitted are provided on an inner peripheral surface of the insertion hole. A through hole penetrating to an outer peripheral surface of the bearing case is provided in the groove, and a stop pin is inserted through the through hole, and the ring foil is fixed to the bearing case by engaging the stop pin with a notch formed in the protrusion.

Prior Art Documents

Patent Documents

[0003] <00000!6>

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the method of attaching the foil of the radial foil bearing as described above, further improvement in ease of assembly is desired. The present disclosure describes a radial foil bearing that is easy to assemble.

Means for Solving the Problems

[0005] A radial foil bearing according to one aspect of the present disclosure is a radial foil bearing that surrounds and supports a rotating shaft, comprising: a bearing housing; a through hole formed in the bearing housing through which the rotating shaft is inserted; a groove provided on the inner circumferential surface of the through hole; a through hole having an opening formed in the groove and extending to the outer circumferential surface of the bearing housing; a regulating pin inserted through the through hole and also extending into the groove; and a top foil disposed in the through hole, wherein the groove is formed to reach the axial end face of the bearing housing, the circumferential end of the top foil is disposed in the groove, and the regulating pin intersects or contacts the inner surface of the groove at multiple locations. [Effects of the Invention]

[0006] According to this disclosure, a radial foil bearing that is easy to assemble can be provided. [Brief explanation of the drawing]

[0007] [Figure 1] This is a side view showing the main part of a rotating machine to which the radial foil bearing of this embodiment is applied. [Figure 2] (a) is a front view of the radial foil bearing of the first embodiment as seen from the axial direction, and (b) is a partially cutaway side view showing the radial foil bearing in a partially cutaway state. [Figure 3] This is a front view showing a magnified view of the bearing foil, etc. [Figure 4] (a) is an unfolded view showing the bearing foil laid out on a plane, and (b) is a perspective view showing both ends of the bearing foil. [Figure 5] (a) is a side view of a radial foil bearing according to the second embodiment, and (b) is a perspective view showing both ends of the bearing foil. [Figure 6] (a) is a side view of a radial foil bearing according to the third embodiment, and (b) is a perspective view showing both ends of the bearing foil. [Figure 7](a) is a side view of a radial foil bearing according to the fourth embodiment, and (b) is a perspective view showing both ends of the bearing foil. [Figure 8] (a), (b), and (c) are front views showing the radial foil bearings of the fifth, sixth, and seventh embodiments as viewed from the axial direction, respectively. [Figure 9] (a) and (b) are front views showing the radial foil bearings of the eighth and ninth embodiments as viewed from the axial direction, respectively. [Figure 10] (a) is an unfolded view showing the bearing foil according to the modified example laid out on a plane, and (b) is a perspective view showing both ends of the bearing foil. [Modes for carrying out the invention]

[0008] A radial foil bearing according to one aspect of the present disclosure is a radial foil bearing that surrounds and supports a rotating shaft, comprising: a bearing housing; a through hole formed in the bearing housing through which the rotating shaft is inserted; a groove provided on the inner circumferential surface of the through hole; a through hole having an opening formed in the groove and extending to the outer circumferential surface of the bearing housing; a regulating pin inserted through the through hole and also extending into the groove; and a top foil disposed in the through hole, wherein the groove is formed to reach the axial end face of the bearing housing, the circumferential end of the top foil is disposed in the groove, and the regulating pin intersects or contacts the inner surface of the groove at multiple locations.

[0009] A pair of the regulating pins may be positioned to sandwich the end of the top foil in the direction of the extension of the groove. Alternatively, the regulating pins may pass through holes provided in the end of the top foil within the groove, and the top foil may be installed in a manner that allows for displacement corresponding to the dimensional difference between the regulating pins and the holes.

[0010] The regulating pin may pass through the end of the top foil within the groove. One end of the regulating pin may be screwed into a female screw hole provided on the inner surface of the groove. The regulating pin may extend through the groove with both ends protruding outside the bearing housing, and both ends of the regulating pin may be provided with retaining portions to restrict displacement in the direction of pulling out of the bearing housing. When viewed in the direction of extension of the groove, the regulating pin and the end of the top foil may overlap.

[0011] Hereinafter, each embodiment of the radial foil bearing according to this disclosure will be described in detail with reference to the drawings. In the following, identical or equivalent components are denoted by the same reference numerals, and redundant descriptions are omitted. Furthermore, the drawings may exaggerate the characteristics of parts, and the dimensional ratios of each part in the drawings do not necessarily match those of the actual object, nor do they necessarily match between different drawings.

[0012] (First Embodiment) Figure 1 is a side view showing the main part of a rotating machine 90 to which the radial foil bearing 1 of this embodiment is applied. The radial foil bearing 1 is used as a radial bearing for the rotating shaft 5 of the impeller 3 of the rotating machine 90. Examples of such rotating machines 90 include turbines, compressors, superchargers, etc. The radial foil bearing 1 of this embodiment is not limited to bearings for the impeller rotating shaft, but can also be used as a bearing for the rotating shafts of electric motors, generators, etc. In the description of the radial foil bearing 1, when simply referred to as "axial direction," "radial direction," and "circumferential direction," it means the axial direction, radial direction, and circumferential direction of the rotating shaft 5 in the operating state of the rotating machine 90.

[0013] The rotating machine 90 comprises a rotating shaft 5 that rotates around a rotation axis A and an impeller 3 provided at the tip of the rotating shaft 5. A thrust collar 7 is provided on the rotating shaft 5, and a pair of thrust bearings 9, 9 are provided on the housing side of the rotating machine 90 so as to sandwich the thrust collar 7 in the axial direction. A radial foil bearing 1 is positioned further from the impeller 3 than these thrust bearings 9, 9. The radial foil bearing 1 is attached to the housing side of the rotating machine 90 and is positioned to surround the rotating shaft 5, supporting the rotating shaft 5.

[0014] Figure 2(a) is a front view of the radial foil bearing 1 as seen from the axial direction, and Figure 2(b) is a partially cutaway side view showing the bearing housing 13 of the radial foil bearing 1 in a cutaway manner. As shown in the figures, the radial foil bearing 1 is equipped with a circular bearing housing 13. Note that the bearing housing 13 is not necessarily circular. An insertion hole 15 for inserting a rotating shaft 5 is formed in the center of the bearing housing 13. The insertion hole 15 is circular when viewed from the axial direction with the rotation axis A as the center, and penetrates the bearing housing 13 in the axial direction. The radial foil bearing 1 is also equipped with a bearing foil 19. The bearing foil 19 is arranged along the inner circumferential surface 17 of the insertion hole 15. In the gap between the outer circumferential surface of the rotating shaft 5 inserted into the insertion hole 15 and the inner circumferential surface 17 of the insertion hole 15, the bearing foil 19 extends circumferentially over approximately one full rotation.

[0015] FIG. 3 is a front view showing an enlarged view of the inner peripheral surface 17 of the insertion hole 15 and the bearing foil 19 on the inner peripheral surface 17. FIG. 4(a) is a developed view showing the state where the bearing foil 19 is developed on a plane, and FIG. 4(b) is a perspective view showing both end portions 19a and 19b of the bearing foil 19. As shown in FIG. 3, the bearing foil 19 is composed of a top foil 20a, an intermediate foil 20b, and a back foil 20c that are stacked in order from the inner peripheral side. The top foil 20a is a flat metal thin plate that faces the outer peripheral surface of the rotating shaft 5 with a slight gap, and forms a fluid film that supports the rotating shaft 5 by drawing fluid into the gap. The back foil 20c is a corrugated metal thin plate, and elastically supports the intermediate foil 20b and the top foil 20a by the structure of a so-called bump foil. The intermediate foil 20b is a flat metal thin plate that is disposed sandwiched between the top foil 20a and the back foil 20c.

[0016] In FIG. 2(a), in order to avoid complication of the drawing, the bearing foil 19 is shown as if it were a single metal thin plate. However, actually, the three foils 20a, 20b, and 20c as described above form the same planar developed shape shown in FIG. 4(a) and are stacked in the thickness direction to constitute the bearing foil 19. That is, the bearing foil 19 shown in FIG. 4(a) is formed by stacking three foils 20a, 20b, and 20c (FIG. 3) having the same planar developed shape in the depth direction of the drawing. In the drawings after FIG. 4, in order to avoid complication of the drawing, the bearing foil 19 is shown as if it were a single metal thin plate, similar to FIG. 2(a). Also, hereinafter, unless otherwise specified, the bearing foil 19 will be described as if it were an integral unit like a single metal thin plate.

[0017] As shown in Fig. 4(a), the bearing foil 19 is in the shape of a strip in a flat-expanded state. One end portion 19b in the circumferential direction of the bearing foil 19 is formed in a convex shape, and the other end portion 19a is formed in a concave shape corresponding to the convex shape. This strip-shaped bearing foil 19 is rolled into a cylindrical shape around the rotation axis A so that its both end portions 19a and 19b are joined together and installed in the insertion hole 15. Thereby, the bearing foil 19 extends along the inner circumferential surface 17 of the insertion hole 15 with the repulsive force due to the deformation into a cylindrical shape. At this time, as shown in Fig. 4(b), when the protrusions and depressions of both end portions 19a and 19b of the bearing foil 19 mesh with each other, as shown in Fig. 2(a), when viewed in the axial direction, both end portions 19a and 19b intersect each other in an X shape.

[0018] On the inner circumferential surface 17 of the insertion hole 15, a groove 21 that is recessed toward the outer side in the radial direction is formed. The groove 21 is a bottomed groove with a rectangular cross-section that has a depth in the radial direction and extends in the axial direction, and extends over the entire axial length of the insertion hole 15. That is, the groove 21 reaches the both end faces 13c and 13d in the axial direction of the bearing housing 13, and the cross-section of the groove 21 appears on the both end faces 13c and 13d in the axial direction of the bearing housing 13. The groove 21 has three inner surfaces. One of these inner surfaces is a groove bottom surface 21c that is orthogonal to the radial direction, and the other two are groove side surfaces 21a and 21b that are orthogonal to the groove bottom surface 21c and parallel to the rotation axis A. Both end portions 19a and 19b of the bearing foil 19 are locally returned to a flat plate shape by the repulsive force to the deformation into a cylindrical shape, and are inserted into the groove 21 in a state of intersecting in an X shape as described above. Incidentally, the groove 21 in the present embodiment is recessed in a rectangular shape substantially parallel in the radial direction, but this is merely an example. For example, the groove 21 may be a groove that is inclined so as to include a circumferential component together with a radial component and is recessed toward the outer diameter side, and the cross-sectional shape does not necessarily have to be rectangular. For example, a form in which a smaller depression is further formed on the rectangular inner wall may be used. Also, the groove 21 in the present embodiment is parallel in the axial direction. However, the groove 21 does not necessarily have to extend parallel in the axial direction. For example, it may extend while being inclined so as to include a circumferential component together with an axial component.

[0019] The mechanism for restricting the axial displacement of the bearing foil 19 installed in the insertion hole 15 as described above will now be explained. The bearing housing 13 is provided with two pin holes 23, 23, and restricting pins 25, 25 are inserted into these pin holes 23, 23, respectively. As shown in Figure 2(b), the pin holes 23, 23 are located one at each of the axial ends of the bearing housing 13, and the ends 19a, 19b of the bearing foil 19 are positioned so as to be sandwiched axially between the pin holes 23, 23.

[0020] The pin insertion opening 23j of the pin hole 23 is located on the outer circumferential surface 13a of the bearing housing 13, and the pin hole 23 is formed to extend linearly from the outer circumferential surface 13a through the groove 21. If we define a virtual plane S as a virtual plane that includes the axis of rotation A and passes through the circumferential center of the groove 21, then the pin hole 23 extends in a direction perpendicular to the virtual plane S, and perpendicularly penetrates the groove side surfaces 21a and 21b along the way. In other words, the pin hole 23 extends in a direction intersecting the virtual plane that includes the axis of rotation A and passes through the groove 21, and intersects with the inner surface of the groove 21 at two points along the way.

[0021] Hereinafter, the portion of the pin hole 23 closer to the pin insertion opening 23j than the groove side surface 21a will be referred to as the "pin hole base end side 23a," and the portion of the pin hole 23 closer to the tip than the groove side surface 21b will be referred to as the "pin hole tip end side 23b." The pin hole base end side 23a is a through hole that opens into the groove 21 on the groove side surface 21a and extends to the outer circumferential surface 13a of the bearing housing 13. The pin hole tip end side 23b is a bottomed hole that opens into the groove 21 on the groove side surface 21b. Furthermore, while the pin hole base end side 23a is a through hole, the pin hole tip end side 23b is a tapped hole with internal threads. The pin hole tip end side 23b can also be described as an internal threaded hole provided on the groove side surface 21b within the groove 21.

[0022] The regulating pin 25 is a rod-shaped metal member that extends linearly and has a diameter that allows it to be inserted into the pin hole 23. At least the tip end of the regulating pin 25 has a male threaded portion 25b that can be screwed into the female threaded portion of the pin hole tip end 23b. The male threaded portion 25b may be formed along the entire length of the regulating pin 25. In addition, the base end of the regulating pin 25 has a head 25a for attaching a tool, and the regulating pin 25 can be rotated around its axis using this tool. A bolt may be used as the regulating pin 25. When assembling the radial foil bearing 1, the tip end of the regulating pin 25 is inserted into the pin hole 23 from the pin insertion opening 23j, and the tip of the regulating pin 25 passes through the groove 21 and reaches the pin hole tip end 23b formed on the groove side surface 21b. Then, when the head 25a is rotated by a tool outside the bearing housing 13, the male threaded portion 25b of the regulating pin 25 is screwed into the pin hole tip end 23b. In this way, the tip of the regulating pin 25 is screwed into the tip side 23b of the pin hole, thereby fixing the regulating pin 25 to the bearing housing 13 and preventing it from coming out of the bearing housing 13. Note that the presence of the head 25a is an example and is not essential.

[0023] The regulating pin 25, installed in this manner, can be said to intersect the inner surfaces 21a to 21c of the groove 21 at multiple points when viewed in the axial direction. More specifically, the regulating pin 25 intersects the inner surfaces 21a to 21c at a total of two points: one point on groove surface 21a and one point on groove surface 21b. Furthermore, as shown in Figure 2(a), when viewed in the extending direction (axial direction) of the groove 21, the regulating pin 25 is positioned within the groove 21, overlapping with both ends 19a and 19b of the bearing foil 19. If we define a virtual plane S as a virtual plane that includes the axis of rotation A and passes through the circumferential center of the groove 21, then the regulating pin 25 can be said to extend in a direction intersecting the virtual plane S and pass through the groove 21. More specifically, the regulating pin 25 extends in a direction perpendicular to the virtual plane S. Furthermore, as shown in Figure 2(b), when viewed in the direction of extension of the regulating pins 25, the two regulating pins 25, 25 are located outside the axial ends 19c, 19d of the bearing foil 19, respectively.

[0024] As described above, the two regulating pins 25, 25 are positioned to sandwich both ends 19a, 19b in the axial direction, and when viewed in the direction of extension of the groove 21 (axial direction), the regulating pins 25 are positioned overlapping with both ends 19a, 19b of the bearing foil 19 within the groove 21. With this arrangement, if the bearing foil 19 attempts to displace axially within the insertion hole 15, both ends 19a, 19b interfere with the regulating pins 25, preventing the displacement. In other words, the presence of the regulating pins 25 restricts the axial displacement of the bearing foil 19 within the insertion hole 15. The portion of the top foil 20a housed in the groove 21 is included in both ends 19a, 19b housed in the groove 21, and these ends 19a, 19b extend radially outward from the regulating pins 25. That is, when viewed axially, a portion of the top foil 20a protrudes radially outward from the regulating pins 25 within the groove 21.

[0025] Furthermore, in order to obtain the effect of friction damping, the regulating pins 25 may be allowed to be displaced slightly in the axial direction. That is, the distance between the two regulating pins 25 may be slightly wider than the axial width of the portion of the top foil 20a that is housed in the groove 21. Alternatively, the top foil 20a may be housed in the groove 21 so as to be spaced apart from at least one of the two regulating pins 25.

[0026] Furthermore, in this embodiment, the portion of the top foil 20a that is housed in the groove 21 is not fixed to the groove 21. Therefore, the portion of the top foil 20a housed in the groove 21 can be displaced and deformed within the groove 21, contributing to an improvement in the damping performance of the radial foil bearing 1.

[0027] In the radial foil bearing 1 with the above configuration, the axial displacement restriction of the bearing foil 19, including the top foil 20a, intermediate foil 20b, and back foil 20c, is realized by components such as two regulating pins 25, 25. Furthermore, the axial displacement restriction of the bearing foil 19 is assembled by a relatively simple procedure in which the strip-shaped bearing foil 19 is rolled up and placed in the insertion hole 15, and then the regulating pins 25, 25 are inserted from outside the bearing housing 13 in a direction that intersects the aforementioned virtual plane S within the groove 21. Therefore, the radial foil bearing 1 can be easily assembled according to its configuration.

[0028] The second to eighth embodiments of the radial foil bearing will be described below. The radial foil bearings of the second to eighth embodiments described below will also provide the same effects and advantages as the first embodiment described above. In the descriptions of each embodiment below, the differences from the first embodiment and other embodiments will be mainly explained.

[0029] (Second Embodiment) Figure 5(a) is a side view of the radial foil bearing 52 according to the second embodiment. In the radial foil bearing 1 according to the first embodiment, the two regulating pins 25, 25 are located outside the axial ends 19c, 19d of the bearing foil 19, respectively. In contrast, the radial foil bearing 52 of this embodiment differs in that the two regulating pins 25, 25 are located inside the axial ends 19c, 19d of the bearing foil 19. To enable this positional relationship, as shown in Figure 5(b), rectangular notches 19h, 19h are formed at the circumferential end 19a of the bearing foil 19 at the corners intersecting with the axial ends 19c, 19d. The regulating pins 25, 25 pass through these notches 19h, 19h, as shown by the dashed lines in the figure. In this way, the bearing foil 19 avoids interference with the regulating pins 25, 25 by the notches 19h, 19h, so that the axial ends 19c, 19d of the bearing foil 19 protrude outward from the regulating pins 25, 25.

[0030] (Third embodiment) As shown in Figures 6(a) and 6(b), in the radial foil bearing 53 according to the third embodiment, instead of the notches 19h, 19h in the second embodiment, holes 19j, 19j are formed at the circumferential end 19a of the bearing foil 19, and as shown by the dashed lines in the figures, the regulating pins 25, 25 pass through these holes 19j, 19j.

[0031] Viewed from the direction of extension of the regulating pin 25, the diameter of the hole 19j is slightly larger than the diameter of the regulating pin 25, and there is a small gap between the inner edge of the hole 19j and the outer surface of the regulating pin 25. Therefore, the axial, radial, and circumferential displacement of the bearing foil 19 is not completely prevented by the regulating pin 25. In other words, the bearing foil 19 is installed in a state where displacement corresponding to the dimensional difference between the regulating pin 25 and the hole 19j is possible; that is, the portion of the top foil 20a housed in the groove 21 is not fixed to the groove 21. Therefore, the portion of the top foil 20a housed in the groove 21 is capable of displacement and deformation within the groove 21.

[0032] (Fourth Embodiment) As shown in Figures 7(a) and 7(b), in the radial foil bearing 54 according to the fourth embodiment, the two regulating pins 25, 25 in the third embodiment are reduced to one and moved to the axial center of the bearing housing 13. Correspondingly, the hole 19j is also moved to the axial center of the bearing foil 19, and the regulating pin 25 passes through this hole 19j.

[0033] In this embodiment as well, similar to the third embodiment described above, the bearing foil 19 is installed in a state that allows for displacement corresponding to the dimensional difference between the regulating pin 25 and the hole 19j.

[0034] (Fifth embodiment) As shown in Figure 8(a), the radial foil bearing 55 according to the fifth embodiment is equipped with a pin hole tip side 61b instead of the pin hole tip side 23b, which is a bottomed tapped hole in the first embodiment. The pin hole tip side 61b is a through hole that opens into the groove 21 on the groove side 21b and extends to the outer circumferential surface 13a of the bearing housing 13. Correspondingly, the regulating pin 63 extends so that both ends protrude from one location 13h and another location 13k on the outer circumferential surface 13a of the bearing housing 13. After the regulating pin 63 is inserted through the pin hole base end side 23a and the pin hole tip side 61b, the ends of the regulating pin 63 are bent to form bent portions 63a, 63a slightly outside the outer circumferential surface 13a. These bent portions 63a, 63a function as retainers to prevent the regulating pin 63 from coming out.

[0035] (Sixth Embodiment) As shown in Figure 8(b), the radial foil bearing 56 according to the sixth embodiment is equipped with a bolt 65 that functions as a regulating pin, instead of the regulating pin 63 in the fifth embodiment. Instead of the bent portions 63a, 63a, a nut 66 is screwed onto the tip of the bolt 65 on the outside of the outer circumferential surface 13a. In addition, seating surfaces 67 are provided on the outer circumferential surface 13a, on which the head 65a of the bolt 65 and the nut 66 are fixed. The tightening of the bolt 65 and nut 66 in this manner prevents the bolt 65, which acts as a regulating pin, from coming loose. That is, the head 65a of the bolt 65 and the nut 66 function as a retaining part that restricts the displacement of the bolt 65 in the direction of coming loose.

[0036] (Seventh Embodiment) As shown in Figure 8(c), the radial foil bearing 57 according to the seventh embodiment is equipped with a bearing foil 69 instead of the bearing foil 19 in the first embodiment. While the ends 19a and 19b of the bearing foil 19 mesh and intersect within the groove 21, the circumferential ends 69a and 69b of the bearing foil 69 are bent radially outward within the groove 21 and do not intersect with each other when viewed in the axial direction.

[0037] (Eighth embodiment) As shown in Figure 9(a), the radial foil bearing 58 according to the eighth embodiment is equipped with a bearing foil 71 instead of a bearing foil 19. The bearing foil 71 is composed of three bearing foils 71H, 71J, and 71K, which have approximately equal circumferential dimensions to each other, connected in the circumferential direction, and surrounds the rotating shaft 5 (see Figure 1). The circumferential connection structure of the bearing foils 71H, 71J, and 71K is similar to the connection structure by interlocking the protrusions and recesses of the ends 19a and 19b as shown in Figure 4(b). Each bearing foil 71H, 71J, and 71K is composed of a top foil 20a, an intermediate foil 20b, and a back foil 20c, similar to the bearing foil 19 (see Figure 3). Three grooves 21 are formed in the bearing housing 73 at equal intervals in the circumferential direction. One circumferential end 71a of each bearing foil 71H, 71J, and 71K is inserted into the groove 21, while the other circumferential end 71b is not inserted into the groove 21 and is located on the inner circumferential surface 17 of the insertion hole 15. The circumferential end 71a inserted into the groove 21 is positioned axially between two regulating pins 25 that are aligned in the depth direction of the paper in the figure. When viewed in the extending direction (axial direction) of the groove 21, the regulating pins 25 and the circumferential end 71a are positioned in overlapping positions within the groove 21.

[0038] (Ninth Embodiment) As shown in Figure 9(b), in the radial foil bearing 59 according to the ninth embodiment, the pin hole tip side 23b (see Figure 2(a)) in the first embodiment is omitted, and the tip of the regulating pin 25 abuts against and contacts the groove side surface 21b. In this case, a female threaded portion may be provided on the pin hole base end side 23a for fixing the regulating pin 25, and the male threaded portion of the regulating pin 25 may be screwed into this female threaded portion.

[0039] This disclosure can be implemented in various forms, including the embodiments described above, with various modifications and improvements based on the knowledge of those skilled in the art. Furthermore, the following modified examples can be constructed using the technical matters described in the embodiments described above. The configurations of each embodiment and modified example may be used in appropriate combinations.

[0040] For example, the interlocking of the ends 19a and 19b of the bearing foil 19 is not limited to the structure shown in Figure 4(b), and various structures can be adopted. For example, the bearing foil 19 may have the unfolded shape shown in Figure 10(a), and the interlocking of its ends 19a and 19b may have the structure shown in Figure 10(b). Also, in each embodiment, the bearing foil 19, which is made up of three foils (top foil 20a, intermediate foil 20b, and back foil 20c) stacked together, is subject to axial displacement restriction by the regulating pins 25, 63, and 65. However, in this disclosure, it is sufficient that at least the top foil 20a of these three foils is subject to axial displacement restriction by the regulating pins 25, 63, and 65. Furthermore, in all of the embodiments described above, the groove 21 extends to both axial end faces of the housing, but the groove 21 may have a bottom on one side in the axial direction. In other words, one axial side of the groove 21 does not need to reach the axial end face of the housing. In that case, there may be only one regulating pin 25 in the groove. [Explanation of Symbols]

[0041] 1, 52, 53, 54, 55, 56, 57, 58, 59 Radial foil bearings 5. Rotation axis 13 Bearing housing 13a Outer surface 13c both end faces 13d Both end faces 15 Through hole 17 Inner surface 19 Bearing foil 19a End 19b End 20a Top Foil 21 Groove 21a Groove side (inner side) 21b Groove side (inner side) 21c Groove bottom (inner surface) 23 pin holes 25, 63, 65 Regulatory pins 23a Pin hole base end side (through hole) 23b Pinhole tip side 63a Bending section (retaining section) 65a Head (retaining part) 66. Nut (retaining part) 69 Bearing foil 71H bearing foil 71J bearing foil 71K bearing foil 71a Circumferential end 73 Bearing Housing

Claims

1. A radial foil bearing that surrounds and supports a rotating shaft, Bearing housing and The bearing housing has an insertion hole formed therein through which the rotating shaft is inserted, A groove provided on the inner circumferential surface of the insertion hole, A through hole is formed within the groove and extends to the outer surface of the bearing housing, A regulating pin is inserted through the aforementioned through hole and extends into the aforementioned groove, The system comprises a top foil disposed within the insertion hole, The groove is formed to reach the axial end face of the bearing housing, The circumferential end of the top foil is positioned within the groove. The regulating pins intersect or contact the inner surface of the groove at multiple points and restrict the axial displacement of the top foil. The circumferential ends of the top foil are arranged to intersect when viewed from the axial direction. A radial foil bearing in which a pair of regulating pins are arranged to sandwich both ends of the top foil in the direction of extension of the groove.

2. Of the two ends of the top foil, one end is a convex end, and the other end is a concave end that interlocks with the convex end. The radial foil bearing according to claim 1, wherein both ends are positioned between the pair of regulating pins.

3. The radial foil bearing according to claim 1 or 2, wherein one end of the regulating pin is screwed into a female screw hole provided on the inner surface of the groove.

4. The radial foil bearing according to claim 1 or 2, wherein the regulating pin extends through the groove and both ends protrude to the outside of the bearing housing, and the ends of the regulating pin are provided with retaining portions that restrict displacement in the direction of dislodgement from the bearing housing.

5. The radial foil bearing according to claim 1 or 2, wherein the regulating pin and the end of the top foil overlap when viewed in the extending direction of the groove.

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