WO2017169842A1

WO2017169842A1 - File bearing

Info

Publication number: WO2017169842A1
Application number: PCT/JP2017/010637
Authority: WO
Inventors: 真人吉野; 藤原　宏樹
Original assignee: Ntn株式会社
Priority date: 2016-03-30
Filing date: 2017-03-16
Publication date: 2017-10-05

Abstract

This file bearing 10 is provided with a top file unit Tf having a bearing surface X, a back file unit Bf elastically supporting the top file unit Tf from the back, and a file holder 11 to which the top file unit Tf and the back file unit Bf are attached, and a shaft 2 is supported in a contactless manner by the fluid pressure occurring in the bearing gap between the shaft 2 and the bearing surface X, which rotate relative to one another. Multiple notches 12b1 are provided on the downstream-side end 12b of the top file unit Tf. The back file unit Bf contacts the top file unit TF at multiple locations separated in the direction orthogonal to the direction of rotation of the shaft (the radial direction).

Description

Foil bearing

The present invention relates to a foil bearing.

A foil bearing is a flexible metal thin plate (foil) that forms a bearing surface. When the foil bends, the bearing clearance varies depending on operating conditions such as shaft rotation speed, load, and ambient temperature. It has the feature of being automatically adjusted to an appropriate width.

For example, the following Patent Document 1 discloses a foil bearing called a bump type as an example of a thrust foil bearing that supports a thrust load. As shown in FIG. 16, the foil bearing includes a top foil 114, a back foil 112 (bump foil) that elastically supports the top foil 114 from behind, and a base plate 110 to which the top foil 114 and the back foil 112 are attached. And have.

When the shaft rotates, a wedge-shaped bearing gap C is formed between the bearing surface 114a of the top foil 114 and the thrust collar 115 with the gap width decreasing toward the downstream side. The fluid pressure is increased when the fluid in the large gap portion C1 of the bearing gap C is pushed into the small gap portion C2, and the thrust collar 115 is supported in a non-contact manner. At this time, the back foil 112 is elastically deformed by the fluid pressure, so that the top foil 114 is allowed to bend and the gap width of the bearing gap C is automatically adjusted.

In addition, Patent Document 3 below discloses a foil bearing called a bump type as an example of a foil bearing. This foil bearing includes a top foil having a bearing surface and a corrugated back foil (bump foil) that elastically supports the top foil from the back. In the back foil, crests that are in contact with the top foil and flat troughs are alternately formed in the rotation direction of the shaft.

Japanese Utility Model Publication No. 61-36725 JP 2013-87789 A JP 2013-47555 A

In a foil bearing as shown in FIG. 16, the fluid (air) in the bearing gap C flows downstream as the shaft rotates. At this time, the fluid in the vicinity of the thrust collar 115 easily flows due to the shearing force with the thrust collar 115, but the fluid separated from the thrust collar 115 does not easily flow. For this reason, only a part of the fluid in the bearing gap C (particularly, the fluid in the large gap portion C1) flows, and the amount of fluid flowing into the small gap portion C2 may be insufficient, and the fluid pressure may not be sufficiently increased. .

For example, in the above Patent Document 3, a structure for increasing the load capacity of a foil bearing is proposed. Specifically, a plurality of notches are provided at the downstream end of each top foil. Thereby, the fluid pushed into the small gap portion C2 passes through the notch portion to the back side of the top foil, and the flow of the fluid in the large gap portion C1 adjacent to the downstream side of the top foil is disturbed. Due to this turbulent flow, the fluid in the large gap portion C1 dynamically flows, thereby increasing the amount of fluid pushed into the small gap portion C2 and increasing the load capacity of the foil bearing.

However, even if the structure as in Patent Document 3 is adopted, the load capacity of the foil bearing may not be sufficient.

Therefore, a first object of the present invention is to further increase the load capacity of the foil bearing.

Also, in the foil bearing shown in Patent Document 2 above, when the pressure in the bearing gap increases with the rotation of the shaft, the back foil is compressed in the width direction of the bearing gap through the top foil. At this time, the corrugated back foil is deformed so as to crush each peak, but the deformation resistance at that time is large, and the back foil is highly rigid as a whole. It tends to run short. When the flexibility of the top foil is insufficient, the function of automatically adjusting the bearing gap is impaired, and problems such as easy contact between the shaft and the top foil are caused.

Therefore, the present inventors have proposed a foil bearing having a back foil 320 as shown in FIG. 38 in the previous application (Japanese Patent Application No. 2015-234626). The back foil 320 includes a flat portion 321 (intermediate portion), a plurality of upper convex portions 322 (first protruding portions) protruding from the flat portion 321 to the top foil side, and a flat portion 321 on the opposite side of the top foil 310. It has a plurality of protruding lower protrusions 323 (second protrusions).

As shown in FIG. 39, the back foil 320 is disposed between the top foil 310 and the foil holder 302 (in FIG. 39, the back foil 320 is schematically shown by a spring). When the shaft rotates, a wedge-shaped bearing gap C is formed between the bearing surface of the top foil 310 and the end face 303a of the thrust collar 303 provided on the shaft, and the fluid in the large gap portion C1 of the bearing gap C is a small gap. The fluid pressure is increased by being pushed into the part C2. With this fluid pressure, the back foil 320 is elastically compressed in the width direction of the bearing gap C (up and down direction in FIG. 39), and thereby the width of the bearing gap C is automatically adjusted. At this time, since the flat portion 321 (see FIG. 38) of the back foil 320 is a portion having a relatively low rigidity with respect to the compressive force, when the compressive force is applied to the back foil 320, the flat portion 321 first. Deforms and absorbs the compressive force. Therefore, the rigidity of the entire back foil can be reduced and the flexibility of the bearing surface can be increased as compared with the corrugated back foil as disclosed in Patent Document 2.

As shown in FIG. 40, the top foil 310 has a plurality of upper convex portions 322 provided on the back foil 320. The top foil 310 is separated from the back at a plurality of positions separated in a direction orthogonal to the axis rotation direction (left-right direction in FIG. Contact supported. In this case, in the top foil 310, the contact portion A with the upper convex portion 322 of the back foil 320 has high rigidity, and the periphery of the contact portion A has low rigidity. Therefore, when the top foil 310 is pressed against the back foil 320 by the fluid pressure generated in the bearing gap C, the region around the contact portion A is farther from the thrust collar 303 than the contact portion A, as shown in FIG. It deforms (lower side in the figure), thereby forming a recess B in a region between the contact portions A. In this case, as shown by an arrow in FIG. 42, the fluid pushed into the small gap portion C2 of the bearing gap C is likely to be released downstream through the recess B. Therefore, as shown by the solid line in the lower stage of FIG. The fluid pressure P that gradually increases as it goes from the large gap portion C1 to the small gap portion C2 drops at an early stage in the small gap portion C2, and the supporting force is reduced.

In view of the circumstances as described above, the second object of the present invention is at a plurality of locations where the top foil is separated in a direction orthogonal to the relative rotation direction of the shaft (hereinafter, this direction is referred to as “rotation orthogonal direction”). In a foil bearing that is contact-supported by a back foil, a supporting force is increased by suppressing a decrease in fluid pressure in the bearing gap.

[First invention]
A first invention made to achieve the above first object includes a top foil part having a bearing surface, a back foil part elastically supporting the top foil part from the back, the top foil part, And a foil holder to which the back foil portion is attached, and a foil bearing that supports the shaft in a non-contact manner by a fluid pressure generated in a bearing gap between the shaft that rotates relative to the bearing surface. A plurality of notches are provided at the downstream end, and the back foil is in contact with the top foil at a plurality of positions separated in a direction orthogonal to the relative rotation direction of the shaft.

Incidentally, the “downstream side” means the upstream side in the relative rotational direction of the shaft (see the direction of arrow R in FIG. 2), that is, the downstream side in the fluid flow direction with respect to the top foil part at the time of relative rotation of the shaft. The opposite side is called the “upstream side”.

In this way, by providing a plurality of notches at the downstream end of the top foil part, a part of the high-pressure fluid flowing through the bearing gap is passed through the notch part on the back side of the top foil part (the back foil part). Turbulent flow occurs in a relatively wide gap (large gap) adjacent to the downstream side of the top foil portion. At this time, the back foil portion is in contact with the top foil portion at a plurality of locations separated in a direction orthogonal to the relative rotation direction of the shaft (hereinafter referred to as “rotation orthogonal direction”). The fluid in the gap between the foil portions (the gap between the foils) can flow downstream through the non-contact portion (between the rotation directions of the contact portions) between the top foil portion and the back foil portion. Therefore, due to the turbulent flow generated in the large gap portion, the fluid between the foil gaps is pulled downstream and flows into the large gap portion, thereby increasing the amount of fluid and increasing the load capacity.

In addition, if the back foil part is brought into contact with the foil holder at a plurality of locations separated in the direction orthogonal to the rotation direction, the fluid in the gap between the back foil part and the foil holder (foil under gap) is transferred to the back foil part and the foil holder. It is possible to flow downstream through the non-contact part (between the rotation orthogonal direction of the contact part). Therefore, due to the turbulent flow generated in the large gap portion, the fluid in the gap under the foil is pulled downstream and flows into the large gap portion, thereby further increasing the amount of fluid and further increasing the load capacity.

The back foil part includes, for example, a flat part, a plurality of first protrusions protruding on the front side (top foil part side) of the flat part, and a plurality of second protrusions protruding on the back side (foil holder side) of the flat part. And have. In this case, the flat portion is a portion having low rigidity against the compressive force in the width direction of the bearing gap (direction perpendicular to the bearing surface) in the back foil portion. Therefore, when a compressive force is applied to the back foil portion due to the fluid pressure generated in the bearing gap with the relative rotation of the shaft, the flat portion is deformed to absorb the compressive force. Therefore, the local rigidity can be reduced as compared with the existing bump-type back foil (see FIG. 16) that does not have such a flat portion. As a result, during normal operation in which a load is applied to the entire bearing surface, rigidity is increased by supporting the top foil portion with the entire back foil portion, and when an uneven load is applied to the bearing surface due to misalignment (center misalignment), By locally deforming the back foil portion, it is possible to prevent the shaft from hitting one side.

In the above foil bearing, if a plurality of notches are provided at the downstream end of the back foil portion, the fluid turbulence effect is further enhanced, so that the amount of fluid flowing into the next bearing gap is further increased. Can do. In particular, by arranging the downstream end of the back foil portion on the downstream side of the downstream end of the top foil portion, the turbulence effect by the notch portion of the back foil portion is further enhanced.

[Second invention]
A second invention made to achieve the second object described above comprises a top foil part having a bearing surface, and a back foil part elastically supporting the top foil part from the back, and a relative shaft In the foil bearing that supports the shaft in a non-contact manner with the fluid pressure generated in the bearing gap between the shaft and the bearing surface as it rotates.
The back foil portion includes a support portion that supports and supports the top foil portion at a plurality of locations separated in a direction orthogonal to the relative rotation direction of the shaft.
Rigidity imparting means for forming a weir continuously provided in a direction orthogonal to the relative rotational direction by increasing the rigidity against deformation toward the side away from the shaft near the downstream end of the top foil part. Is provided.

Specifically, as an example of the second invention, a top foil part having a bearing surface and a back foil part that elastically supports the top foil part from the back are provided. In the foil bearing that supports the shaft in a non-contact manner with a fluid pressure generated in a bearing gap between the back foil portion and the bearing surface, the back foil portion extends the top foil portion in a direction orthogonal to the relative rotation direction of the shaft. A first support portion that contacts and supports at a plurality of spaced locations, and a second support that is provided downstream of the first support portion and continuously contacts and supports the top foil portion in a direction orthogonal to the relative rotation direction. And a foil bearing.

When the fluid pressure in the bearing gap increases with the relative rotation of the shaft, the top foil portion is contacted and supported by the first support portion of the back foil portion at a plurality of locations separated in the direction orthogonal to the rotation. Is deformed to the side away from the shaft (side to widen the bearing gap), and a recess is formed on the bearing surface (see FIG. 41). In the present invention, since the region on the downstream side of the concave portion of the top foil portion is continuously contacted and supported in the rotation orthogonal direction by the second support portion of the back foil portion, the rigidity of this region is enhanced. As a result, even when the fluid pressure in the bearing gap is increased, the region of the top foil portion that is supported by the second support portion of the back foil portion is less likely to be deformed to the side away from the shaft. In addition, a weir that is one step higher than the concave portion (arranged on the shaft side) is formed. In this case, the fluid that has flowed downstream through the concave portion of the top foil portion is blocked by the weir formed on the downstream side, so that the outflow of fluid from the bearing gap is suppressed. Therefore, as shown by the dotted line in the lower part of FIG. 39, a decrease in fluid pressure in the small gap portion C2 of the bearing gap C is suppressed, and the supporting force is increased.

It is preferable that the second support part of the back foil part continuously contacts the top foil part in the entire region in the direction orthogonal to the rotation. As a result, a weir is formed on the downstream side of the concave portion of the top foil portion over the entire length in the direction perpendicular to the rotation direction, so that a decrease in fluid pressure is further effectively suppressed.

The second support part can be constituted by, for example, a curved part that protrudes toward the top foil part.

In the above foil bearing, for example, the back foil portion includes a flat portion, a plurality of upper convex portions protruding from the flat portion toward the top foil portion, and a plurality of protrusions protruding from the flat portion to the opposite side of the top foil portion. The first support portion can be configured by the plurality of upper convex portions. Alternatively, the back foil portion is provided with a corrugated portion alternately having a plurality of crests and troughs extending in a direction intersecting with the rotation direction of the shaft in the relative rotation direction. A support part can be comprised.

Further, as another example of the second invention, a top foil portion having a bearing surface and a back foil portion that elastically supports the top foil portion from the back are provided. In a foil bearing that supports the shaft in a non-contact manner with a fluid pressure generated in a bearing gap between the bearing surface and the bearing surface, the back foil portion is a region of the top foil portion where the bearing surface is provided. A support portion that contacts and supports at a plurality of locations separated in a direction perpendicular to the relative rotation direction of the shaft, and the top foil portion is located on a downstream side of the bearing surface in a region adjacent to the downstream side of the bearing surface. Provided is a foil bearing having a bent portion which is bent along the end portion on the side away from the shaft.

When the fluid pressure in the bearing gap increases with the relative rotation of the shaft, the top foil part is contacted and supported by the back foil part supporting part at a plurality of positions separated in the rotation orthogonal direction. Is deformed to the side away from the shaft (side to widen the bearing gap), and a recess is formed on the bearing surface (see FIG. 41). In the present invention, by providing the bent portion in the region adjacent to the downstream side of the bearing surface of the top foil portion, the rigidity of the region near the end portion on the downstream side of the bearing surface is enhanced. As a result, even when the fluid pressure in the bearing gap is increased, the region near the end on the downstream side of the bearing surface is not easily deformed to the side away from the shaft, so this region is one step higher than the recess. A weir (arranged on the shaft side) is formed. As a result, the fluid that has flowed downstream through the concave portion of the bearing surface is blocked by the weir formed on the downstream side, so that the outflow of fluid from the small gap portion of the bearing gap is suppressed. Therefore, as shown by the dotted line in the lower part of FIG. 39, a decrease in fluid pressure in the small gap portion is suppressed, and the supporting force is improved.

The bent portion can be formed, for example, by bending the vicinity of the downstream end portion of the top foil portion. In this case, the bent portion is bent with respect to the bearing surface of the top foil portion. Alternatively, the bent portion can be formed by curving the vicinity of the end portion on the downstream side of the top foil portion into a curved surface. In this case, the bent portion is in a curved state so as to be smoothly continuous with the bearing surface.

The above bent portion can be formed by bending the end portion on the downstream side of the top foil portion plastically or elastically.

For example, an insertion part is provided at the downstream end of the top foil part, and an insertion port is provided near the upstream end of the top foil part, and the insertion part of each top foil part is adjacent to the downstream side. If it inserts in the insertion port of the top foil part to perform, the downstream edge part vicinity of a top foil part can be elastically bent to the side away from an axis | shaft.

In the above foil bearing, if the shaft swings, the shaft contacts the end of the top foil portion in the direction perpendicular to the rotation, and the top foil portion may be damaged. Therefore, if a bent portion is provided in a region excluding the end portion in the rotation orthogonal direction in the top foil portion, rigidity at the end portion in the rotation orthogonal direction of the top foil portion can be suppressed. The contact surface pressure is reduced, and damage to the top foil portion can be prevented.

The foil bearing described above includes, for example, a plurality of foil members integrally including a top foil portion and a back foil portion, and the top foil portion of each foil member is arranged on the back foil portion of another foil member. Can be configured.

As described above, according to the first invention, the load capacity of the foil bearing can be increased.

Further, according to the second invention, since the decrease in fluid pressure in the bearing gap can be suppressed, the supporting force of the foil bearing can be increased.

It is sectional drawing of the foil bearing (thrust foil bearing) which concerns on 1st Embodiment of 1st invention. It is a top view of the foil bearing of FIG. It is a perspective view which shows the foil bearing of FIG. 1 typically. It is a perspective view of the back foil provided in the foil bearing of FIG. FIG. 5 is a sectional view taken along line VV in FIG. 2. It is sectional drawing of the foil bearing of FIG. It is sectional drawing of the foil bearing which concerns on 2nd Embodiment of 1st invention. It is sectional drawing of the foil bearing which concerns on 3rd Embodiment of 1st invention. The upper stage is a plan view of the back foil according to the fourth embodiment of the first invention. The lower part is a cross-sectional view taken along line YY of the upper part. It is a top view of the back foil which concerns on 5th Embodiment of 1st invention. It is sectional drawing of the foil bearing which concerns on 6th Embodiment of 1st invention. It is sectional drawing of the foil bearing which concerns on 7th Embodiment of 1st invention. It is a top view of the foil which concerns on 8th Embodiment of 1st invention. It is a perspective view of the foil bearing which has the foil of FIG. It is sectional drawing of the foil bearing (radial foil bearing) which concerns on 9th Embodiment of 1st invention. It is sectional drawing of the conventional foil bearing. It is sectional drawing of the foil bearing which concerns on 1st Embodiment of 2nd invention. It is a top view of the foil bearing of FIG. FIG. 18 is a perspective view of a top foil and a back foil provided on the foil bearing of FIG. 17. FIG. 20 is a plan view of the back foil of FIG. 19. FIG. 20 is a perspective view of the back foil of FIG. 19. FIG. 20 is a cross-sectional view of the downstream end of the back foil of FIG. 19. It is sectional drawing of the downstream end part of the back foil which concerns on another example. It is the VV sectional view taken on the line of FIG. FIG. 20 is a plan view of the top foil of FIG. 19. FIG. 26 is a cross-sectional view taken along the line U-U in FIG. 25. FIG. 26 is a cross-sectional view taken along line TT in FIG. 25. It is sectional drawing of the foil bearing of FIG. It is a top view of the back foil which concerns on 2nd Embodiment of 2nd invention. It is sectional drawing of the foil bearing which concerns on 3rd Embodiment of 2nd invention. The upper part is a plan view of a back foil according to the fourth embodiment of the second invention, and the lower part is a cross-sectional view taken along line YY of the plan view. It is sectional drawing of the back foil which concerns on 5th Embodiment of 2nd invention. It is sectional drawing of the foil bearing which concerns on 6th Embodiment of 2nd invention. It is a top view of the foil of the foil bearing of FIG. It is a top view of the foil which concerns on 7th Embodiment of 2nd invention. FIG. 36 is a perspective view of a foil bearing having the foil of FIG. It is sectional drawing of the foil bearing which concerns on 8th Embodiment of 2nd invention. It is a perspective view of the back foil proposed in the prior application. The upper stage is a cross-sectional view of a foil bearing having the back foil of FIG. 38, and the lower stage is a graph showing the pressure distribution of the upper foil bearing. FIG. 40 is a cross-sectional view taken along line WW in FIG. 39, showing a state where the fluid pressure in the bearing gap is low. FIG. 40 is a cross-sectional view taken along the line WW in FIG. 39, showing a state where the fluid pressure in the bearing gap is high. FIG. 40 is a plan view of a top foil of the foil bearing of FIG. 39. It is sectional drawing of the foil bearing which concerns on 9th Embodiment of 2nd invention. It is a top view of the foil bearing of FIG. It is a perspective view of the top foil and back foil provided in the foil bearing of FIG. FIG. 46 is a plan view of the back foil of FIG. 45. FIG. 46 is a perspective view of the back foil of FIG. 45. It is sectional drawing of the downstream edge part of the top foil which concerns on another example. It is sectional drawing of the downstream edge part of the top foil which concerns on another example. It is the VV sectional view taken on the line of FIG. FIG. 46 is a plan view of the top foil of FIG. 45. FIG. 52 is a cross-sectional view taken along the line U-U in FIG. 51. FIG. 52 is a sectional view taken along line TT in FIG. 51. It is sectional drawing of the foil bearing of FIG. It is a perspective view of the top foil and back foil which concern on 10th Embodiment of 2nd invention. It is a perspective view of the top foil and back foil which concern on 11th Embodiment of 2nd invention. It is a top view of the back foil which concerns on 12th Embodiment of 2nd invention. It is sectional drawing of the foil bearing which concerns on 13th Embodiment of 2nd invention. The upper part is a plan view of the back foil according to the fourteenth embodiment of the second invention, and the lower part is a cross-sectional view taken along line YY of the plan view. It is sectional drawing of the foil bearing which concerns on 15th Embodiment of 2nd invention. It is a perspective view of the foil concerning 16th Embodiment of 2nd invention. FIG. 62 is a perspective view of a foil bearing having the foil of FIG. 61. It is a perspective view of the foil bearing which concerns on 17th Embodiment of 2nd invention. FIG. 64 is a plan view showing another example of a foil incorporated in the foil bearing of FIG. 63. It is sectional drawing of the foil bearing which concerns on 18th Embodiment of 2nd invention. FIG. 66 is a plan view of a foil of the foil bearing of FIG. 65. It is sectional drawing of the foil bearing which concerns on 19th Embodiment of 2nd invention.

Hereinafter, an embodiment of the first invention of the present invention will be described with reference to FIGS.

As shown in FIG. 1, the foil bearing 10 according to the first embodiment of the present invention is an air film formed between the disc-shaped thrust collar 3 provided on the shaft 2, and the shaft 2 is moved in the thrust direction. It is a thrust foil bearing to support. The foil bearing 10 includes a disc-shaped foil holder 11, and a top foil 12 and a back foil 13 attached to an end surface 11 a of the foil holder 11. In the present embodiment, as shown in FIG. 2, a plurality (six in the illustrated example) of fan-shaped top foil 12 and back foil 13 are arranged side by side in the rotation direction of shaft 2 (the circumferential direction of foil holder 11). The

The foil holder 11 is made of metal or resin. The foil holder 11 has a hollow disk shape having an inner hole 11b into which the shaft 2 is inserted. A plurality of top foils 12 and back foils 13 are attached to one end surface 11 a of the foil holder 11. The other end surface 11c of the foil holder 11 is fixed to a housing of a facility (for example, a turbo machine such as a gas turbine) in which the foil bearing 10 is incorporated.

The top foil 12 and the back foil 13 are formed of a metal having a high spring property and good workability, for example, steel or a copper alloy. The top foil 12 and the back foil 13 are formed of a thin metal plate (foil) having a thickness of about 20 μm to 200 μm. In the air dynamic pressure bearing using air as a fluid film as in the present embodiment, since there is no lubricating oil in the atmosphere, it is preferable to form the top foil 12 and the back foil 13 with stainless steel or bronze.

As shown in FIGS. 2 and 3, the top foil 12 has a smooth bearing surface X without irregularities and functions as a top foil portion Tf. In FIG. 3, the

foils

12 and 13 are shown in a rectangular shape for simplification of the drawing. The upstream end 12 a of the top foil 12 is fixed to the end surface 11 a of the foil holder 11. In the illustrated example, the upstream end portion 12 a of the top foil 12 is fixed to the end surface 11 a of the foil holder 11 through a spacer 15 by welding or the like. The upstream end 12 a of the top foil 12 may be directly fixed to the end surface 11 a of the foil holder 11 without using the spacer 15. The top foil 12 is formed in a substantially fan-shaped flat plate shape having a notch 12b1 by subjecting the foil to press processing (punching processing) or electric discharge processing.

The downstream end 12b of the top foil 12 is a free end. The downstream end 12b of the top foil 12 is provided with a plurality of notches 12b1. The plurality of cutout portions 12b1 are arranged in the rotation orthogonal direction (radial direction in the present embodiment) along the edge of the downstream end portion 12b of the top foil 12. In the example of illustration, each notch part 12b1 comprises a triangle, and the edge of the edge part 12b of the downstream of the top foil 12 is formed in zigzag shape. The shape of each notch 12b1 is not limited to the above, and may be an arc, an elliptical arc, a trapezoid, a rectangle, a waveform, or the like. In the illustrated example, the plurality of cutout portions 12b1 are continuously arranged in the radial direction. However, the present invention is not limited to this, and the plurality of cutout portions 12b1 are provided intermittently in the radial direction. An edge extending in the radial direction may be left between the radial directions of 12b1.

The back foil 13 is disposed between the top foil 12 and the foil holder 11 and functions as a back foil portion Bf that elastically supports the top foil 12 from behind. The back foil 13 has a fan shape that is substantially the same shape as the top foil 12 in a plan view, and is disposed so as to overlap directly below the top foil 12. The upstream end 13 a of the back foil 13 is fixed to the end surface 11 a of the foil holder 11. In the present embodiment, the upstream end 13 a of the back foil 13 is fixed to the end surface 11 a of the foil holder 11 by welding or the like via the spacer 15. Note that the upstream end portion 13 a of the back foil 13 may be directly fixed to the end surface 11 a of the foil holder 11 without using the spacer 15.

The back foil 13 has a shape that can be compressed in the axial direction by elastic deformation. As shown in FIG. 4, the back foil 13 of the present embodiment includes a flat portion 13b substantially parallel to the end surface 11a of the foil holder 11, and a plurality of first protrusions protruding from the flat portion 13b to the front side (top foil 12 side). Part (upward convex part 13c) and a plurality of second projecting parts (lower convex part 13d) projecting from the flat part 13b to the back side (foil holder 11 side). In addition, although the upper convex part 13c and the lower convex part 13d are set as the name which attached "upper" and "lower" so that these relative positional relationships may be understood easily, this limits the usage aspect of the foil bearing 10. FIG. It is not the purpose.

The flat portion 13b, the upper convex portion 13c, and the lower convex portion 13d of the back foil 13 have a uniform thickness. Both the upper convex portion 13c and the lower convex portion 13d are formed in a substantially hemispherical shape. Since the inside of the upper convex portion 13c and the lower convex portion 13d is hollow, for example, when the back foil 13 is viewed from the front side (top foil 12 side), the region where the lower convex portion 13d exists is a concave portion. A flat portion 13b is provided on the entire circumference of the upper convex portion 13c and the lower convex portion 13d. The upper convex portion 13c and the lower convex portion 13d are provided at a plurality of locations separated in the rotation direction and the rotation orthogonal direction, respectively. The upper convex portion 13c and the lower convex portion 13d in the illustrated example are each distributed and arranged over the entire region except for the vicinity of the upstream end portion 13a of the back foil 13. Further, in the illustrated example, a plurality of upper convex portions 13 c are arranged in the radial direction in the immediate vicinity of the downstream end portion 13 e of the back foil 13. In addition, the arrangement pattern of the upper convex part 13c and the lower convex part 13d shown in FIG. 4 is only an example, and an arbitrary arrangement pattern different from that in FIG.

In the present embodiment, at least a partial region (entire region in the illustrated example) of the cutout portion 12b1 of the top foil 12 is provided so as to overlap the flat portion 13b of the downstream end portion 13e of the back foil 13 in the axial direction (FIG. 5). reference). In the illustrated example, the downstream end 12b of the top foil 12 and the downstream end 13e of the back foil 13 are provided at the same rotational direction position.

The back foil 13 is formed by forming a substantially fan-shaped flat foil material by subjecting the foil to press processing (punching) or electric discharge processing, and then pressing the foil material to form an upper convex portion 13c and a lower convex portion. It is formed by molding 13d. It should be noted that the stamping of the foil material and the molding of the upper convex portion 13c and the lower convex portion 13d can be simultaneously performed by pressing. The overall axial dimension of the back foil 13 including the upper convex portion 13c and the lower convex portion 13d is about 0.5 to 2 mm.

When the shaft 2 and the thrust collar 3 rotate in one circumferential direction (in the direction of arrow R), the bearing is provided between the bearing surface X of each top foil 12 of the foil bearing 10 and the end surface 3a of the thrust collar 3 as shown in FIG. A gap C is formed. At this time, the top foil 12 is curved, so that the bearing gap C has a wedge-shaped cross section that becomes narrower toward the downstream side. Then, the air in the bearing gap C flows downstream by the shearing force between the thrust collar 3 and the air, so that the air is pushed into the small gap portion C2 of the bearing gap C (see arrow A in FIG. 5). . As a result, the pressure of the air film in the bearing gap C is increased, and the shaft 2 and the thrust collar 3 are supported in a non-contact manner in the thrust direction by this pressure.

At this time, as shown in FIG. 6, since the top foil 12 receives the pressure P due to the air pressure generated in the bearing gap C, a compressive force in the pressure P direction acts on the back foil 13 via the top foil 12. Since the flat portion 13b has a thin plate shape extending in a direction orthogonal to the pressure P direction, the flat portion 13b is a portion of the back foil 13 having low rigidity against the compression force. Therefore, when a compressive force is applied to the back foil 13, the flat portion 13b is first deformed and absorbs the compressive force as shown by a two-dot chain line in FIG. Therefore, the rigidity of the back foil 13 can be locally reduced as compared with an existing corrugated back foil having no flat portion. Thereby, since the flexibility of the bearing surface X is increased, the bearing surface X of the top foil 12 is elastically deformed according to the operating conditions such as the load, the rotational speed of the shaft 2 and the ambient temperature, and the bearing gap C becomes the operating condition. It is automatically adjusted to the appropriate width. Therefore, the bearing gap C can be managed to the optimum width even under severe conditions such as high temperature and high speed rotation, and the shaft 2 can be stably supported.

Moreover, in this embodiment, by providing the notch part 12b1 in the downstream end part 12b of the top foil 12, a part of the air flowing through the bearing gap C is disposed on the back side of the top foil 12 via the notch part 12b1. Exit (see arrow A1 in FIG. 5). Thereby, since the air flow in the space (large gap C1) adjacent to the downstream side of the top foil 12 is disturbed, the air in the large gap C1 dynamically flows and is formed by the next top foil 12. The amount of air flowing into the small gap portion C2 of the bearing gap C increases, and the load capacity of the foil bearing 10 is increased.

At this time, since the back foil 13 and the top foil 12 are in contact with each other at a plurality of locations separated in the radial direction, air flows downstream in the gap between the back foil 13 and the top foil 12 (interfoil gap D). A flow path capable of flowing to the side is formed. The downstream end of this flow path communicates with the large gap C1. In the present embodiment, the upper protrusions 13c dispersedly arranged on the back foil 13 come into contact with the back surface of the top foil 12, so that the air in the gap D between the foils is not contacted between the foils 12 and 13 (upper It is possible to flow downstream through the convex portion 13c). When turbulent flow occurs in the large gap C1 due to the notch 12b1 of the top foil 12, the air in the gap D between the foils is pulled and flows downstream, and flows into the large gap C1 (see FIG. 5). (See arrow B). Thereby, the amount of air flowing into the bearing gap C formed by the next top foil 12 is further increased, and the load capacity of the foil bearing 10 is further increased.

In particular, in this embodiment, the cutout portion 12b1 of the top foil 12 is disposed so as to overlap the flat portion 13b in the vicinity of the downstream end portion 13e of the back foil 13 in the axial direction. In this case, the fluid B flowing along the flat portion 13b of the back foil 13 joins the high-speed fluid A flowing through the bearing gap C, so that the fluid in the inter-foil gap D is easily pulled downstream, and the large gap The amount of fluid flowing into the part C1 further increases.

Furthermore, in this embodiment, the back foil 13 and the foil holder 11 contact at a plurality of locations separated in the radial direction. Thereby, a flow path in which air can flow downstream is formed in the gap between the back foil 13 and the foil holder 11 (foil lower gap E). The downstream end of this flow path communicates with the large gap C1. In the present embodiment, the lower protrusions 13d dispersedly arranged on the back foil 13 come into contact with the end surface 11a of the foil holder 11, so that the air in the gap under the foil E is not in contact with the back foil 13 and the foil holder 11. It is possible to flow downstream through the contact portion (between the radial directions of the lower convex portion 13d). When turbulent flow is generated in the large gap C1 due to the notch 12b1 of the top foil 12, not only the air in the gap D between the foils but also the air in the gap E under the foil is pulled and flows downstream. Since it flows into the clearance C1, the amount of air flowing into the small clearance C2 of the bearing clearance C formed by the next top foil 12 further increases, and the load capacity of the foil bearing 10 is further increased.

Note that the bearing surface X of each top foil 12 and the end surface 3a of the thrust collar 3 are in sliding contact with each other at the time of low-speed rotation immediately before the shaft 2 is stopped or immediately after it is started. A low friction coating such as a titanium aluminum nitride film, a tungsten disulfide film, or a molybdenum disulfide film may be formed.

Further, during the rotation of the shaft 2, a minute slide occurs between the top foil 12 and the back foil 13 or between the back foil 13 and the end surface 11 a of the foil holder 11. The vibration of the shaft 2 can be attenuated by the frictional energy generated by the minute sliding. In order to adjust the frictional force due to such micro-sliding, the above-described low-friction coating may be formed on one or both of the mutually sliding surfaces.

The present invention is not limited to the above embodiment. Hereinafter, although other embodiment of this invention is described, description is abbreviate | omitted about the point which overlaps with said embodiment.

7, at least a partial region (entire region in the illustrated example) of the notch portion 12b1 of the top foil 12 protrudes from the downstream end portion 13e of the back foil 13 to the downstream side. In this case, since the space on the back side (the foil holder 11 side) of the notch 12b1 is larger than that in the embodiment shown in FIG. 5, the fluid in the bearing gap C is easily removed through the notch 12b1.

In the embodiment shown in FIG. 8, the notch 12b1 is provided at the downstream end 12b of the top foil 12, and the notch 13e1 is provided at the downstream end 13e of the back foil 13. The notch 13e1 of the back foil 13 has the same configuration as the notch 12b1 of the top foil 12, and has a triangular shape, for example. The air flows into the back side of the back foil 13 through the notch 13e1 (see arrow B1), so that the turbulence effect in the large gap C1 is enhanced. In this case, as shown in FIG. 8, the downstream end 13e of the back foil 13 is arranged on the downstream side of the downstream end 12b of the top foil 12, and at least a part of the notch 13e1 of the back foil 13 ( If the entire region in the illustrated example is disposed so as to protrude downstream from the downstream end 12b of the top foil 12, the turbulent flow effect by the notch 13e1 of the back foil 13 is enhanced.

In the embodiment shown in FIG. 9, the back foil 13 has a waveform having alternately a plurality of peaks 13f1 and valleys 13f2 extending in a predetermined direction. In the illustrated example, the peak portion 13f1 and the valley portion 13f2 extend along a direction intersecting with the edge of the downstream end portion 13e, and extend in a direction parallel to the edge of the upstream end portion 13a of the back foil 13, for example. In this case, the peak portion 13f1 of the back foil 13 contacts the region near the downstream end of the top foil 12 at a plurality of locations separated in the radial direction. As a result, when the shaft 2 rotates, the air in the inter-foil gap D flows downstream through the valley 13f2 of the back foil 13 and flows into the large gap C1.

By the way, when the corrugated back foil 13 as shown in FIG. 9 is formed by pressing, the flat foil material is bent into a corrugated shape, so that the dimensions in plan view (the extent of the peaks 13f1 and troughs 13f2) are accordingly increased. The dimension in the direction orthogonal to the current direction is reduced. Therefore, the flat foil material before the press work needs to be set in shape and dimensions in consideration of the reduction in dimensions due to the press work, so that the design becomes very complicated. On the other hand, as shown in FIG. 4, the back foil 13 in which a large number of upper convex portions 13 c and lower convex portions 13 d are dispersedly arranged is obtained by pressing a flat foil material and locally stretching the material. The upper convex portion 13c and the lower convex portion 13d can be formed. In this case, since the overall dimensions in a plan view are hardly changed by pressing, the upper convex portion 13c and the lower convex portion 13d can be freely designed, and the design of the back foil 13 is facilitated.

Also, in the foil bearing 10 described above, the rigidity of the bearing surface X can be partially controlled by changing the distribution density of the upper protrusions 13c and the lower protrusions 13d provided on the back foil 13 depending on the location. For example, in the embodiment shown in FIG. 10, the density of the upper convex portion 13c and the lower convex portion 13d increases as going to the downstream side. In this case, the rigidity of the back foil 13 in the compression direction (axial direction) increases as it goes downstream. As a result, the bearing surface X of the top foil 12 is less likely to be deformed in the direction away from the thrust collar 3 (the direction in which the bearing gap C is widened) as it goes downstream, so that a wedge-shaped bearing gap C is easily formed. .

Further, in the foil bearing 10 described above, a bearing surface having a predetermined shape can be obtained by changing the height of the upper convex portion 13c and the lower convex portion 13d provided on the back foil 13 depending on the location. For example, in the embodiment shown in FIG. 11, the height (axial dimension) of the back foil 13 including the upper convex portion 13 c and the lower convex portion 13 d becomes larger toward the downstream side. As a result, the bearing surface X of the top foil 12 tends to be displaced toward the thrust collar 3 toward the downstream side, and a wedge-shaped bearing gap C is easily formed.

The embodiment shown in FIG. 12 includes a foil member 14 that integrally includes a top foil portion Tf and a back foil portion Bf (the back foil portion Bf is indicated by a dotted pattern). The upstream end of each foil member 14 is attached to the foil holder 11. In a state where the plurality of foil members 14 are attached to the foil holder 11, the back foil portion Bf of the foil member 14 adjacent to the downstream side is disposed between the top foil portion Tf of each foil member 14 and the foil holder 11. . The back foil part Bf of each foil member 14 contacts the top foil part Tf of the foil member 14 stacked on the foil member 14 at a plurality of locations separated in the radial direction. A notch portion 12b1 similar to that shown in FIGS. 2 and 3 is provided at the downstream end portion of the top foil portion Tf of each foil member.

In the embodiment shown in FIG. 13, as in the embodiment shown in FIG. 12, each foil member 14 has a top foil portion Tf and a back foil portion Bf, but the shape of each foil member 14 is shown in FIG. Different from the embodiment. The foil member 14 of FIG. 13 integrally includes a main body 14a having a top foil portion Tf and a back foil portion Bf, and a fixing portion 14b extending from the main body 14a to the outer diameter side and fixed to the foil holder 11. Both of the edge of the upstream end 14a1 and the edge of the downstream end 14a2 of the main body 14a have a shape in which the radially central portion is swollen downstream. The downstream end portion 14a2 of the main body 14a is provided with a plurality of cutout portions 12b1 as in the above embodiment. The back foil portion Bf is provided with a flat portion 13b, an upper convex portion 13c (white circle), and a lower convex portion 13d (black circle). When the foil member 14 of FIG. 13 is attached to the foil holder 11, as shown in FIG. 14, the back foil portion Bf of each foil member 14 is hidden behind the top foil portion Tf of the adjacent foil member 14, and the top foil portion Tf. Only the surface side (thrust color side) is exposed.

In the above embodiment, the case where the present invention is applied to a thrust foil bearing has been shown. However, the present invention can also be applied to a radial foil bearing that supports a shaft in a radial direction. For example, the radial foil bearing 20 shown in FIG. 15 has a cylindrical foil holder 21 and a plurality of foil members 22 attached to the inner peripheral surface 21a of the foil holder 21 side by side in the circumferential direction. Of each foil member 22, the downstream region functions as the top foil portion Tf, and the upstream region functions as the back foil portion Bf (shown with a dotted pattern). A plurality of notches are provided at the downstream end of the top foil portion Tf of each foil member 22 (not shown) as in the above embodiment. The back foil portion Bf contacts the top foil portion Tf of the foil member 22 adjacent to the downstream side at a plurality of locations separated in the axial direction. For example, as in the above-described embodiment, the flat foil portion, the upper convex portion, and the lower convex portion Part. When the shaft 2 rotates, a bearing gap C is formed between the bearing surface X of the top foil portion Tf and the outer peripheral surface of the shaft 2.

In the above embodiment, the case where the foil bearing is fixed and the shaft 2 is rotated is shown. However, the present invention is not limited thereto, and the shaft 2 may be fixed and the foil bearing may be rotated. However, if the foil bearing is rotated, the foil may be damaged by centrifugal force. Therefore, it is preferable to fix the foil bearing as in the above embodiment.

In addition, the foil bearings described above can be used, for example, as bearings for main shafts of turbo machines such as gas turbines and turbochargers (superchargers), bearings for vehicles such as automobiles, or bearings for industrial equipment. It is.

Further, the foil bearing described above can be used not only as an air dynamic pressure bearing using air as a pressure generating fluid but also as an oil dynamic pressure bearing using lubricating oil as a pressure generating fluid.

Hereinafter, first to eighth embodiments of the second invention will be described with reference to FIGS.

As shown in FIG. 17, the foil bearing 210 according to the first embodiment of the present invention is an air film formed between the disk-shaped thrust collar 203 provided on the shaft 202, and the shaft 202 is thrust in the thrust direction. It is a thrust foil bearing to support. The foil bearing 210 includes a disc-shaped foil holder 211, and a top foil 212 and a back foil 213 attached to the end surface 211 a of the foil holder 211. In the present embodiment, as shown in FIG. 18, a plurality (six in the illustrated example) of fan-shaped top foil 212 and back foil 213 are arranged side by side in the rotational direction of shaft 202 (the circumferential direction of foil holder 211). The In the following, the rotation direction leading side of the shaft 202 (in the direction of arrow R in FIG. 18), that is, the downstream side of the fluid flow direction with respect to the top foil 212 when the shaft 202 rotates is referred to as “downstream side” and vice versa. The side is called the “upstream side”.

The foil holder 211 is made of metal or resin. The foil holder 211 has a hollow disk shape having an inner hole 211b into which the shaft 202 is inserted. A plurality of top foils 212 and back foils 213 are attached to one end surface 211 a of the foil holder 211. The other end surface 211c of the foil holder 211 is fixed to a housing of a facility (for example, a turbo machine such as a gas turbine) in which the foil bearing 210 is incorporated.

The top foil 212 and the back foil 213 are formed of a metal having a high spring property and good workability, for example, steel or a copper alloy. The top foil 212 and the back foil 213 are formed of a thin metal plate (foil) having a thickness of about 20 μm to 200 μm. In the air dynamic pressure bearing using air as a fluid film as in the present embodiment, since there is no lubricating oil in the atmosphere, it is preferable to form the top foil 212 and the back foil 213 with stainless steel or bronze.

The top foil 212 functions as a top foil portion Tf having the bearing surface X. As shown in FIGS. 18 and 19, the top foil 212 has a smooth bearing surface X without unevenness. The upstream end 212a of the top foil 212 is fixed to the end surface 211a of the foil holder 211 by welding or the like. An end 212b on the downstream side of the top foil 212 is a free end. The top foil 212 is formed by punching or electric discharge machining a flat foil.

The back foil 213 functions as a back foil portion Bf that supports the top foil 212 from behind. The back foil 213 has a fan shape that is substantially the same shape as the top foil 212 in plan view, and is placed directly below the top foil 212 (see FIG. 19). The upstream end 213a of the back foil 213 is fixed to the end surface 211a of the foil holder 211 by welding or the like.

As shown in FIG. 20, the back foil 213 includes a first region Q1 that occupies most of the region excluding both ends in the circumferential direction, and a second region Q2 provided at the downstream end. The first region Q1 of the back foil 213 is provided with a first support portion that comes into contact with the top foil 212 at a plurality of locations separated in the radial direction. In the present embodiment, as shown in FIG. 21, in the first region Q1, a flat portion 213b, a plurality of upper convex portions 213c protruding from the flat portion 213b to the top foil 212 side, and a flat foil 213b to the top foil 212, A plurality of lower convex portions 213d protruding to the opposite side are provided, and the upper convex portion 213c constitutes the first support portion. In addition, although the upper convex part 213c and the lower convex part 213d are made the name which attached "upper" and "lower" so that these relative positional relationships may be understood easily, this limits the use aspect of the foil bearing 210. It is not the purpose.

The flat part 213b, the upper convex part 213c, the lower convex part 213d, and the curved part 213e described later have a uniform thickness of the back foil 213. Both the upper convex part 213c and the lower convex part 213d are formed in a substantially hemispherical shape. Since the inside of the upper convex portion 213c and the lower convex portion 213d is hollow, when the back foil 213 is viewed from one side of the front and back sides, for example, from the front side (top foil 212 side) as shown in FIG. A region where 213d exists is a recess. In FIG. 20, the lower convex portion 213d that is a concave portion is hatched for easy understanding. A flat portion 213b is provided on the entire circumference of the upper convex portion 213c and the lower convex portion 213d. The upper convex portion 213c and the lower convex portion 213d are each distributed and arranged over the entire first region Q1. The upper convex portion 213 c is in contact with the back surface (surface opposite to the bearing surface X) of the top foil 212, and the lower convex portion 213 d is in contact with the end surface 211 a of the foil holder 211.

The second region Q2 of the back foil 213 is provided with a second support portion that continuously contacts the top foil 212 in the radial direction. In the present embodiment, a curved portion 213e that protrudes toward the top foil 212 is provided in the second region Q2, and the curved portion 213e constitutes a second support portion (rigidity imparting means). The curved portion 213e extends continuously in the radial direction, and extends, for example, along the edge of the downstream end portion 212b (free end) of the top foil 212, in the illustrated example, along the radial direction. The curved portion 213e is provided in the entire radial direction of the second region Q2, and continuously contacts the entire radial direction of the top foil 212. As shown in FIG. 22, the substantially cylindrical curved surface portion provided at the top of the curved portion 213 e is in contact with the top foil 212. The upstream end of the curved portion 213e is continuous with the flat portion 213b of the first region Q1. The downstream end of the curved portion 213e is curved along the end surface 211a of the foil holder 211. Thereby, when the bending part 213e is compressed, the downstream end part of the bending part 213e can be smoothly deformed while sliding on the end surface 211a of the foil holder 211.

In addition, as shown in FIG. 23, the downstream end of the curved portion 213e may be separated from the end surface 211a of the foil holder 211. In this case, the bending portion 213e is easily displaced in the axial direction, and the rigidity when the back foil 213 is compressed can be suppressed.

The back foil 213 is formed by pressing the foil. In the present embodiment, after forming a flat plate-shaped foil material having a predetermined shape by punching or electric discharge machining, the foil material is subjected to press working to obtain a flat portion 213b, an upper convex portion 213c, a lower convex portion 213d, and a curved portion. By forming the part 213e at the same time, the back foil 213 is formed. The stamping of the foil material and the forming of the flat portion 213b, the upper convex portion 213c, the lower convex portion 213d, and the curved portion 213e can be simultaneously performed by pressing. The thickness direction dimension (axial dimension) of the entire back foil 213 including the upper convex portion 213c and the lower convex portion 213d is about 0.5 to 2 mm. The protruding amount of the upper convex portion 213c and the curved portion 213e with respect to the flat portion 213b is approximately the same. In addition, the arrangement pattern of the upper convex part 213c and the lower convex part 213d shown in FIG. 20 is only an example, and an arbitrary arrangement pattern different from that in FIG. 20 can be adopted as necessary.

As shown in FIG. 24, when the shaft 202 and the thrust collar 203 rotate in one circumferential direction (the direction of the arrow R), the bearings between the bearing surfaces X of the top foils 212 of the foil bearings 210 and the end surfaces 203 a of the thrust collars 203. A gap C is formed. At this time, the top foil 212 is curved, so that the bearing gap C has a wedge shape that becomes narrower toward the downstream side. The air in the large gap C1 of the wedge-shaped bearing gap C is pushed into the small gap C2, thereby increasing the pressure of the air film in the bearing gap C. This pressure causes the shaft 202 and the thrust collar 203 to move in the thrust direction. Contact supported. At this time, the bearing surface X of the top foil 212 is elastically deformed according to the operating conditions such as the load, the rotational speed of the shaft 202, and the ambient temperature, so that the bearing gap C is automatically adjusted to an appropriate width according to the operating conditions. The Therefore, the bearing gap C can be managed to the optimum width even under severe conditions such as high temperature and high speed rotation, and the shaft 202 can be stably supported.

As described above, when the air pressure in the bearing gap C (particularly, the small gap portion C2) is increased, the top foil 212 is pressed against the back foil 213. Specifically, most of the top foil 212 except for the upstream end 212a and the downstream end 212b is supported by the upper convex portion 213c of the back foil 213 and the downstream end 212b of the top foil 212. The nearby region is contact-supported by the curved portion 213e of the back foil 213. At this time, of the top foil 212, the contact portion A that is in contact with the upper convex portion 213c (first support portion) of the back foil 213 has high rigidity, and the periphery of the contact portion A has low rigidity. Therefore, as shown in FIGS. 25 to 27, the region between the radial directions of the contact portion A in the top foil 212 is deformed to the foil holder 211 side (downward in FIGS. 26 and 27) from the contact portion A, A recess B is formed in this region. On the other hand, the region of the top foil 212 where the curved portion 213e (second support portion) of the back foil 213 is in contact has high rigidity and is difficult to be deformed to the foil holder 211 side by air pressure. A weir D having a height higher than that is formed. This weir D extends continuously in the radial direction, and in this embodiment extends over the entire length of the top foil 212 in the radial direction (see FIG. 25).

The air pushed into the small gap portion C2 with the rotation of the shaft 202 passes through the concave portion B of the top foil 212 to the downstream side (see arrow S in FIGS. 25 and 27). However, since the weir D continuously extending in the radial direction is provided on the downstream side of the recess B, the flow of air to the downstream side is restricted. This makes it difficult for air to escape from the small gap portion C2 to the downstream side, and a decrease in air pressure in the small gap portion C2 is suppressed (see the dotted line in the lower stage of FIG. 39). .

During rotation of the shaft 202, the top foil 212 receives pressure P due to the air pressure generated in the bearing gap C as shown in FIG. 28. Therefore, the back foil 213 is compressed in the pressure P direction via the top foil 212. Force acts. Since the flat portion 213b has a thin plate shape extending in a direction orthogonal to the pressure P direction, the back foil 213 is a portion having low rigidity against the compression force. Therefore, when a compressive force is applied to the back foil 213, the flat portion 213b is first deformed and absorbs the compressive force as shown by a two-dot chain line in FIG. Therefore, the rigidity of the back foil 213 can be locally reduced as compared with the back foil portion of an existing bump type foil bearing that does not have such a flat portion. Thereby, since the flexibility of the bearing surface X is increased, the bearing surface X is easily deformed following the displacement of the shaft 202, and the bearing gap C is automatically adjusted to the optimum width, so that the thrust collar 203 and the top foil 212 are adjusted. It is possible to reliably prevent contact with the.

Note that the bearing surface X of each top foil 212 and the end surface 203a of the thrust collar 203 are in sliding contact with each other at the time of low-speed rotation immediately before the shaft 202 is stopped or just after starting. A low friction coating such as a titanium aluminum nitride film, a tungsten disulfide film, or a molybdenum disulfide film may be formed.

Further, during the rotation of the shaft 202, a minute slide occurs between the top foil 212 and the back foil 213 or between the back foil 213 and the end surface 211a of the foil holder 211. The vibration of the shaft 202 can be attenuated by the frictional energy generated by the minute sliding. In order to adjust the frictional force due to such micro-sliding, the above-described low-friction coating may be formed on one or both of the mutually sliding surfaces.

In the foil bearing 210 described above, the rigidity of the bearing surface X can be partially controlled by changing the distribution density of the upper protrusions 213c and the lower protrusions 213d provided in the first region Q1 of the back foil 213 depending on the location. it can. For example, in the second embodiment shown in FIG. 29, the density of the upper protrusions 213c and the lower protrusions 213d increases as going downstream. In this case, the rigidity of the back foil 213 in the compression direction (axial direction) increases as it goes downstream. As a result, the bearing surface X of the top foil 212 is less likely to be deformed in the direction away from the thrust collar 203 (the direction in which the bearing gap C is widened) as it goes downstream, so that a wedge-shaped bearing gap C is easily formed. . In FIG. 29, the back foil 213 is simplified and shown as a rectangle.

Further, in the foil bearing 210 described above, a bearing surface having a predetermined shape can be obtained by changing the height of the upper convex portion 213c and the lower convex portion 213d provided in the first region Q1 of the back foil 213 depending on the location. For example, in the third embodiment shown in FIG. 30, the height (axial dimension) of the back foil 213 including the upper convex portion 213c and the lower convex portion 213d increases toward the downstream side. As a result, the bearing surface X of the top foil 212 tends to be displaced toward the thrust collar 203 toward the downstream side, and a wedge-shaped bearing gap C is easily formed.

In the fourth embodiment shown in FIG. 31, a corrugated portion 213f is provided in the first region Q1 of the back foil 213. The corrugated portion 213 f has a plurality of crest portions 213 f 1 and trough portions 213 f 2 extending along the direction intersecting the rotation direction of the shaft 202 alternately in the rotation direction of the shaft 202. The peak portion 213f1 of the corrugated portion 213f constitutes a first support portion that contacts and supports the top foil 212 from behind. The peak portion 213f1 and the valley portion 213f2 extend in a direction intersecting with the edge of the downstream end portion of the back foil 213, and extend in a direction parallel to the edge of the upstream end portion 213a of the back foil 213 in the illustrated example. In this case, at the downstream end portion of the first region Q1, the peak portions 213f1 are provided at a plurality of locations separated in the radial direction, and these peak portions 213f1 are in contact with the top foil 212. In the second region Q2, the curved portion 213e is provided as in the above embodiment.

The back foil 213 having the corrugated portion 213f as shown in FIG. 31 can be formed by, for example, pressing. In this case, since the flat foil material is bent into a corrugated shape, the dimension in plan view (the dimension in the direction orthogonal to the extending direction of the peak portion 213f1) is reduced accordingly. Therefore, the flat foil material before the press work needs to be set in shape and dimensions in consideration of the reduction in dimensions due to the press work, so that the design becomes very complicated.

On the other hand, the back foil 213 having the dimple-like upper convex portion 213c and the lower convex portion 213d as shown in FIG. 21 is formed by pressing a flat foil material and locally stretching the material to the upper convex portion. 213c and the downward convex part 213d can be shape | molded. In this case, since the overall dimensions in a plan view are hardly changed by pressing, it is possible to freely design the upper convex portion 213c and the lower convex portion 213d, and the design of the back foil 213 is facilitated.

In the fifth embodiment shown in FIG. 32, the second support portion of the back foil portion Bf is constituted by a rod-like member 215. The rod-shaped member 215 is made of metal or resin. The rod-shaped member 215 extends continuously in the radial direction, for example, extends along the edge of the downstream end portion 212b of the top foil 212, specifically, along the radial direction. The rod-shaped member 215 is fixed to the surface of the second region Q2 of the back foil 213 (the surface on the top foil 212 side) by welding or the like. When the pressure in the bearing gap C increases, the rod-shaped member 215 continuously contacts the top foil portion Tf in the radial direction. The cross-sectional shape of the rod-shaped member 215 is not limited to FIG. 32, and may be, for example, an upwardly convex semicircular shape.

33 includes a foil member 214 that integrally includes a top foil portion Tf and a back foil portion Bf (the back foil portion Bf is indicated by a dotted pattern). The upstream end of each foil member 214 is attached to the foil holder 211. In a state where the plurality of foil members 214 are attached to the foil holder 211, the back foil portion Bf of the adjacent foil member 214 is disposed between the top foil portion Tf of each foil member 214 and the foil holder 211. As shown in FIG. 34, the first region Q1 of the back foil portion Bf of each foil member 214 is provided with a first support portion that contacts and supports the top foil portion Tf at a plurality of locations separated in the radial direction. In the illustrated example, a flat portion 213b, an upper convex portion 213c (open circle) as a first support portion, and a lower convex portion 213d (hatched circle) are provided in the first region Q1. In the second region Q2 of the back foil portion Bf of each foil member 214, a second support portion that continuously contacts and supports the top foil portion Tf in the radial direction is provided. In the illustrated example, a curved portion is used as the second support portion. 213e is provided.

In the seventh embodiment shown in FIG. 35, as in the embodiment shown in FIG. 33, each foil member 214 has a top foil portion Tf and a back foil portion Bf, but the shape of each foil member 214 is shown in FIG. Different from the embodiment shown in FIG. The foil member 214 of FIG. 35 has a main body 214a having a top foil portion Tf and a back foil portion Bf, and a fixing portion 214b extending from the main body 214a to the outer diameter side and fixed to the foil holder 211. The edge 214a1 at the downstream end and the edge 214a2 at the upstream end of the main body 214a both have a shape in which the central portion in the radial direction is bulged downstream. The back foil portion Bf is provided with a flat portion 213b, an upper convex portion 213c (open circle) as a first support portion, a lower convex portion 213d (hatching circle), and a curved portion 213e as a second support portion. The curved portion 213e extends in a direction substantially parallel to the edge 214a1 at the downstream end of the main body 214a. Thus, the curved portion 213e does not necessarily have to be parallel to the radial direction, and may be any shape that can continuously contact the top foil portion Tf in the radial direction. When the foil member 214 shown in FIG. 35 is attached to the foil holder 211, the back foil portion Bf of each foil member 214 is hidden behind the top foil portion Tf of the adjacent foil member 214 as shown in FIG. Only Tf is exposed on the front side (thrust color side).

In the above embodiment, the case where the present invention is applied to a thrust foil bearing has been shown. However, the present invention can also be applied to a radial foil bearing that supports a shaft in a radial direction. For example, in the eighth embodiment shown in FIG. 37, the present invention is applied to a so-called leaf-type radial foil bearing 220. The radial foil bearing 220 includes a cylindrical foil holder 221 and a plurality of foil members 222 attached to the inner peripheral surface 221a of the foil holder 221 in a circumferential direction. Of each foil member 222, the downstream region functions as the top foil portion Tf, and the upstream region functions as the back foil portion Bf. In the backfoil portion Bf (indicated by a dotted pattern) of each foil member 222, as in the above-described embodiment, first support portions (for example, upward convex portions) are provided at a plurality of locations separated in the rotation orthogonal direction (axial direction). And a second support portion (for example, a curved portion) that continuously contacts the top foil portion Tf in the axial direction is provided on the downstream side thereof. When the shaft 202 rotates, a bearing gap C is formed between the bearing surface of the top foil portion Tf and the outer peripheral surface of the shaft 202.

In the above embodiment, the case where the second support portion (curved portion) is in contact with the entire region in the rotation orthogonal direction of the top foil portion Tf is shown, but not limited thereto, for example, the dimension in the rotation orthogonal direction of the second support portion. May be slightly smaller than the top foil portion Tf, and the second support portion may be configured to contact and support the region excluding the end portion in the rotation orthogonal direction of the top foil portion Tf.

In the above embodiment, the case where the foil bearing is fixed and the shaft 202 is rotated has been described. However, the present invention is not limited thereto, and the shaft 202 may be fixed and the foil bearing may be rotated. However, if the foil bearing is rotated, the foil may be damaged by centrifugal force. Therefore, it is preferable to fix the foil bearing as in the above embodiment.

Hereinafter, ninth to nineteenth embodiments of the second invention will be described with reference to FIGS.

As shown in FIG. 43, the foil bearing 410 according to the ninth embodiment is an air film formed between the disc-shaped thrust collar 403 provided on the shaft 402 and a thrust that supports the shaft 402 in the thrust direction. It is a foil bearing. The foil bearing 410 includes a disc-shaped foil holder 411, and a top foil 412 and a back foil 413 attached to the end surface 411 a of the foil holder 411. In the present embodiment, as shown in FIG. 44, a plurality (six in the illustrated example) of fan-shaped top foil 412 and back foil 413 are arranged side by side in the rotation direction of shaft 402 (the circumferential direction of foil holder 411). The In the following description, the upstream side in the rotational direction of the shaft 402 (in the direction of arrow R in FIG. 44), that is, the downstream side in the air flow direction with respect to the top foil 412 when the shaft 402 rotates is referred to as “downstream side” and vice versa. The side is called the “upstream side”.

The foil holder 411 is made of metal, resin, or the like. The foil holder 411 has a hollow disk shape having an inner hole 411b into which the shaft 402 is inserted. A plurality of top foils 412 and a back foil 413 are attached to one end surface 411 a of the foil holder 411. The other end surface 411c of the foil holder 411 is fixed to a housing of a facility (for example, a turbo machine such as a gas turbine) in which the foil bearing 410 is incorporated.

The top foil 412 and the back foil 413 are made of a metal having a high spring property and good workability, for example, steel or a copper alloy. The top foil 412 and the back foil 413 are formed of a thin metal plate (foil) having a thickness of about 20 μm to 200 μm. In an air dynamic pressure bearing using air as a fluid film as in the present embodiment, since there is no lubricating oil in the atmosphere, it is preferable to form the top foil 412 and the back foil 413 with stainless steel or bronze.

The top foil 412 functions as a top foil portion Tf having the bearing surface X. As shown in FIGS. 44 and 45, the top foil 412 has a smooth bearing surface X having no irregularities. The upstream end 412a of the top foil 412 is fixed to the end surface 411a of the foil holder 411 by welding or the like.

The downstream end of the top foil 412 is a free end. A bent portion 412b (rigidity imparting means) is provided at the downstream end of the top foil 412 (see FIG. 45). The bent portion 412b is formed by bending the vicinity of the downstream end portion of the top foil 412 to the side away from the thrust collar 403 (the foil holder 411 side). Specifically, after a flat plate-shaped foil material having a predetermined shape is formed by punching or electric discharge machining, an area adjacent to the downstream side of the bearing surface X in the foil material (in the illustrated example, more than the bearing surface X). The bent portion 412b is formed by plastically deforming the downstream band-like region) by pressing or the like. It should be noted that the stamping of the foil material and the formation of the bent portion 412b can be simultaneously performed by pressing. The bent portion 412b extends along the downstream end of the bearing surface X, and extends in the direction orthogonal to the rotation (radial direction) in the illustrated example. The bent portion 412b is bent with respect to the bearing surface X. The angle and dimension of the bent portion 412b are set so that the end portion of the bent portion 412b does not contact the foil holder 411. In the illustrated example, the bent portion 412b is bent in a direction orthogonal to the bearing surface X. The axial dimension of the bent portion 412b is smaller than the axial dimension of the back foil 413, for example, 30 to 70% of the axial dimension of the back foil 413.

The angle between the bearing surface X of the top foil 412 and the bent portion 412b is not limited to a right angle, and this angle may be an acute angle. For example, in the example shown in FIG. 48, the bent portion 412b is formed by folding the vicinity of the downstream end of the top foil 412 about 180 ° upstream. Or as shown in FIG. 49, it is good also considering the angle between the bearing surface X and the bending part 412b as an obtuse angle. Further, as shown in the figure, the end of the bent portion 412b may be brought into contact with the end surface 411a of the foil holder 411. In this case, the rigidity of the region near the end portion on the downstream side of the bearing surface X can be increased. In addition, the bent portion 412b may be normally separated from the end surface 411a of the foil holder 411 so that the bent portion 412b contacts the end surface 411a of the foil holder 411 when the fluid pressure in the bearing gap is increased.

The back foil 413 functions as a back foil portion Bf that supports the top foil 412 from behind. The back foil 413 has a fan shape that is substantially the same shape as the top foil 412 in a plan view, and is arranged to overlap the top foil 412 (see FIGS. 45 and 46). The upstream end 413a of the back foil 413 is fixed to the end surface 411a of the foil holder 411 by welding or the like.

The back foil 413 has support portions that come into contact with the top foil 412 at a plurality of locations separated in the radial direction. In this embodiment, as shown in FIG. 47, the back foil 413 has a flat portion 413b, a plurality of upper convex portions 413c protruding from the flat portion 413b to the top foil 412 side, and the flat portion 413b opposite to the top foil 412. A plurality of lower convex portions 413d protruding to the side are provided, and the upper convex portion 413c constitutes a support portion. In addition, although the upper convex part 413c and the lower convex part 413d are set as the name which attached "upper" and "lower" so that these relative positional relationships may be understood easily, this limits the use aspect of the foil bearing 410. It is not the purpose.

The flat portion 413b, the upper convex portion 413c, and the lower convex portion 413d of the back foil 413 have a uniform thickness. Both the upper convex portion 413c and the lower convex portion 413d are substantially hemispherical. Since the inside of the upper convex portion 413c and the lower convex portion 413d is hollow, when the back foil 413 is viewed from one side of the front and back sides, for example, from the front side (top foil 412 side) as shown in FIG. The region where 413d exists is a recess. In FIG. 46, for easy understanding, the lower convex portion 413d serving as a concave portion is hatched. A flat portion 413b is provided on the entire circumference of the upper convex portion 413c and the lower convex portion 413d. The upper convex part 413c and the lower convex part 413d are respectively distributed and arranged in the whole area except for the vicinity of the upstream end part 413a of the back foil 413. The upper convex portion 413 c comes into contact with the back surface (the surface opposite to the bearing surface X) of the top foil 412, and the lower convex portion 413 d comes into contact with the end surface 411 a of the foil holder 411.

The back foil 413 is formed by pressing the foil. In this embodiment, after forming a flat plate-shaped foil material having a predetermined shape by punching or electric discharge machining, the foil material is pressed to form the upper convex portion 413c and the lower convex portion 413d at the same time. A foil 413 is formed. It should be noted that the stamping of the foil material and the molding of the upper convex portion 413c and the lower convex portion 413d can be simultaneously performed by pressing. The thickness direction dimension (axial dimension) of the entire back foil 413 including the upper convex portion 413c and the lower convex portion 413d is about 0.5 to 2 mm. Note that the arrangement pattern of the upper protrusion 413c and the lower protrusion 413d shown in FIG. 46 is merely an example, and an arbitrary arrangement pattern different from that shown in FIG.

As shown in FIG. 50, when the shaft 402 and the thrust collar 403 are rotated in one circumferential direction (the direction of the arrow R), the bearings between the bearing surface X of each top foil 412 of the foil bearing 410 and the end surface 403a of the thrust collar 403 are supported. A gap C is formed. At this time, the top foil 412 is curved, so that the bearing gap C has a wedge shape that becomes narrower toward the downstream side. The air in the large gap portion C1 of the wedge-shaped bearing gap C is pushed into the small gap portion C2, thereby increasing the pressure of the air film in the bearing gap C. This pressure causes the shaft 402 and the thrust collar 403 to move in the thrust direction. Contact supported. At this time, the bearing surface C of the top foil 412 is elastically deformed according to the operating conditions such as the load, the rotational speed of the shaft 402, and the ambient temperature, so that the bearing gap C is automatically adjusted to an appropriate width according to the operating conditions. The Therefore, the bearing gap C can be managed to the optimum width even under severe conditions such as high temperature and high speed rotation, and the shaft 402 can be stably supported.

As described above, when the air pressure in the bearing gap C (particularly, the small gap portion C2) is increased, the top foil 412 is pressed against the back foil 413. Specifically, most of the top foil 412 except the upstream end portion 412a and the downstream end portion (bending portion 412b) is contact-supported by the upper convex portion 413c of the back foil 413. At this time, in the top foil 412, the contact portion A where the upper convex portion 413c (supporting portion) 413c (support portion) of the back foil 413 contacts has high rigidity, and the periphery of the contact portion A has low rigidity. Therefore, as shown in FIGS. 51 to 53, the region in the radial direction of the contact portion A in the top foil 412 is deformed to the foil holder 411 side (downward in FIGS. 52 and 53) from the contact portion A. A recess B is formed in the region. On the other hand, since a bent portion 412b is formed at the downstream end of the top foil 412, the rigidity of the region along the bent portion 412b (region near the downstream end of the bearing surface X) is increased. Yes. Accordingly, the region near the downstream end portion of the bearing surface X is not easily deformed to the foil holder 411 side by the fluid pressure, and therefore a weir D that is one step higher than the recess B is formed in this region (see FIG. 53). ). This weir D extends continuously in the radial direction, and in this embodiment extends over the entire length of the top foil 412 in the radial direction (see FIG. 51).

The air pushed into the small gap portion C2 with the rotation of the shaft 402 passes through the concave portion B of the top foil 412 to the downstream side (see arrow S in FIGS. 51 and 53). However, since the weir D continuously extending along the bent portion 412b is provided on the downstream side of the recess B, the flow of air to the downstream side is restricted. This makes it difficult for air to escape from the small gap portion C2 to the downstream side, and a decrease in air pressure in the small gap portion C2 is suppressed (see the dotted line in the lower stage of FIG. 39), so that the support force by the foil bearing 410 can be increased. .

During rotation of the shaft 402, as shown in FIG. 54, the top foil 412 receives the pressure P due to the air pressure generated in the bearing gap C. Therefore, the back foil 413 is compressed in the pressure P direction via the top foil 412. Force acts. Since the flat portion 413b has a thin plate shape extending in a direction orthogonal to the pressure P direction, the back foil 413 is a portion having low rigidity against the compression force. Therefore, when a compressive force is applied to the back foil 413, the flat portion 413b is first deformed and absorbs the compressive force as shown by a two-dot chain line in FIG. Therefore, the rigidity of the back foil 413 can be locally reduced as compared with the back foil portion of an existing bump type foil bearing that does not have such a flat portion. Thereby, since the flexibility of the bearing surface X is increased, the bearing surface X easily follows and deforms with respect to the displacement of the shaft 402, and the thrust collar 403, the top foil 412 and the bearing gap C are automatically adjusted to the optimum width. It is possible to reliably prevent the contact of.

Note that the bearing surface X of each top foil 412 and the end surface 403a of the thrust collar 403 are in sliding contact with each other at the time of low-speed rotation immediately before the shaft 402 is stopped or immediately after starting. A low friction coating such as a titanium aluminum nitride film, a tungsten disulfide film, or a molybdenum disulfide film may be formed.

Further, during the rotation of the shaft 402, a minute slide occurs between the top foil 412 and the back foil 413 or between the back foil 413 and the end surface 411a of the foil holder 411. The vibration of the shaft 402 can be attenuated by the frictional energy generated by the minute sliding. In order to adjust the frictional force due to such micro-sliding, the above-described low-friction coating may be formed on one or both of the mutually sliding surfaces.

55, the bent portion 412b is provided only in the intermediate portion excluding both ends in the radial direction among the downstream end portions of the top foil 412. In the tenth embodiment shown in FIG. In this case, the rigidity at both ends in the radial direction in the region near the end portion on the downstream side of the bearing surface X is low. When the shaft 402 swings around, the outer diameter end of the end surface 403a of the thrust collar 403 may come into contact with the outer diameter end of the bearing surface X. However, as described above, the bending portion 412b at the radial end is omitted, By reducing the rigidity of this portion, the surface pressure due to contact with the thrust collar 403 can be suppressed, so that the top foil 412 can be prevented from being damaged. The bent portion 412b may be omitted at only one end portion in the radial direction (for example, only at the outer diameter end) in addition to being omitted at both ends in the radial direction of the top foil 412 as described above.

In the above embodiment, the bent portion 412b of the top foil 412 is bent with respect to the bearing surface X. However, the present invention is not limited to this. For example, in the eleventh embodiment shown in FIG. 56, the bent portion 412b is formed by curving the vicinity of the end portion on the downstream side of the top foil 412 in a curved shape on the side away from the thrust collar 403. In this case, the bent portion 412b has a curved surface portion that is smoothly continuous with the bearing surface X.

In the foil bearing 410 described above, the rigidity of the bearing surface X can be partially controlled by changing the distribution density of the upper protrusions 413c and the lower protrusions 413d provided on the back foil 413 depending on the location. For example, in the twelfth embodiment shown in FIG. 57, the density of the upper protrusions 413c and the lower protrusions 413d increases as going downstream. In this case, the rigidity in the compression direction (axial direction) of the back foil 413 increases as it goes downstream. As a result, the bearing surface X of the top foil 412 is less likely to be deformed in a direction away from the thrust collar 403 (a direction in which the bearing gap C is widened) as it goes downstream, so that a wedge-shaped bearing gap C is easily formed. . In FIG. 57, the back foil 413 is simplified and shown as a rectangle.

Further, in the foil bearing 410 described above, a bearing surface having a predetermined shape can be obtained by changing the heights of the upper convex portion 413c and the lower convex portion 413d provided on the back foil 413 depending on the location. For example, in the thirteenth embodiment shown in FIG. 58, the height (axial dimension) of the back foil 413 including the upper convex portion 413c and the lower convex portion 413d increases toward the downstream side. As a result, the bearing surface X of the top foil 412 tends to be displaced toward the thrust collar 403 toward the downstream side, and a wedge-shaped bearing gap C is easily formed.

In the fourteenth embodiment shown in FIG. 59, the back foil 413 is provided with a corrugated portion 413f. The corrugated portion 413 f has a plurality of peak portions 413 f 1 and valley portions 413 f 2 extending along the direction intersecting the rotation direction of the shaft 402 alternately in the rotation direction of the shaft 402. The peak portion 413f1 of the corrugated portion 413f constitutes a first support portion that contacts and supports the top foil 412 from behind. The peak portion 413f1 and the valley portion 413f2 extend in a direction intersecting with the edge of the downstream end portion of the back foil 413, and extend in a direction parallel to the edge of the upstream end portion 413a of the back foil 413 in the illustrated example. In this case, at the downstream end portion of the back foil 413, the peak portions 413f1 are provided at a plurality of locations separated in the radial direction, and these peak portions 413f1 are in contact with the top foil 412.

The back foil 413 having the corrugated portion 413f as shown in FIG. 59 can be formed by, for example, pressing. In this case, since the flat foil material is bent into a corrugated shape, the dimension in plan view (dimension in the direction orthogonal to the extending direction of the peak portion 413f1) is reduced accordingly. Therefore, the flat foil material before the press work needs to be set in shape and dimensions in consideration of the reduction in dimensions due to the press work, so that the design becomes very complicated.

On the other hand, the back foil 413 having the dimple-like upper convex portion 413c and the lower convex portion 413d as shown in FIG. 47 is formed by pressing the flat foil material and locally stretching the material. 413c and the downward convex part 413d can be shape | molded. In this case, since the overall dimensions in a plan view are hardly changed by pressing, the upper convex portion 413c and the lower convex portion 413d can be freely designed, and the design of the back foil 413 is facilitated.

60 includes a foil member 414 integrally having a top foil portion Tf and a back foil portion Bf (the back foil portion Bf is indicated by a dotted pattern). The upstream end of each foil member 414 is attached to the foil holder 411. In a state where the plurality of foil members 414 are attached to the foil holder 411, the back foil portion Bf of the adjacent foil member 414 is disposed between the top foil portion Tf of each foil member 414 and the foil holder 411. The back foil portion Bf of each foil member 414 is provided with a support portion for contacting and supporting the top foil portion Tf at a plurality of locations separated in the radial direction. For example, a flat portion 413b as shown in FIGS. , An upper convex portion 413c (support portion), and a lower convex portion 413d are provided.

In the above embodiment, the case where the bent portion 412b is formed by plastically deforming the downstream end portion of the top foil 412 is not limited to this, but the downstream end portion of the top foil 412 is not limited to this. The bent portion 412b may be formed by elastic deformation. For example, in the sixteenth embodiment shown in FIG. 61, a foil member 414 integrally including a top foil portion Tf and a back foil portion Bf is provided, and an insertion portion 412c is provided at a downstream end portion of the top foil portion Tf. An insertion port 412d is provided in the vicinity of the upstream end of the top foil portion Tf. As shown in FIG. 62, the insertion portion 412c of each top foil portion Tf is inserted into the insertion port 412d of the top foil portion Tf adjacent to the downstream side. Since the back foil portion Bf is arranged behind the top foil portion Tf (lower side in the figure), the downstream end portion (free end) of the top foil portion Tf is usually on the thrust collar side than the upstream end portion. (Upper in the figure). Therefore, the top foil portion Tf is inserted by inserting the insertion portion 412c provided at the downstream end portion of the top foil portion Tf into the insertion port 412d provided near the upstream end portion of the adjacent top foil portion Tf. The vicinity of the downstream end is elastically curved toward the side away from the shaft (downward in the figure), thereby forming a bent portion 412b. In the illustrated example, the insertion portion 412c and the insertion port 412d are provided only at the center in the radial direction of the top foil portion Tf. You may provide the insertion part 412c and the insertion port 412d.

In the seventeenth embodiment shown in FIG. 63, the top foil 412 having the insertion portion 412c and the insertion port 412d and the back foil 413 are formed separately. In this case, the insertion port 412d of the top foil 412 is not limited to the slit shape as shown in FIG. 63, and may be configured by a recess opened at the upstream end of the top foil 412 as shown in FIG.

In the eighteenth embodiment shown in FIG. 65, as in the embodiment shown in FIG. 60, each foil member 414 has a top foil portion Tf and a back foil portion Bf, but the shape of each foil member 414 is shown in FIG. Different from the embodiment shown in FIG. 65 includes a main body 414a having a top foil portion Tf and a back foil portion Bf, and a fixing portion 414b extending from the main body 414a to the outer diameter side and fixed to the foil holder 411. Both the edge 414a1 at the downstream end and the edge 414a2 at the upstream end of the main body 414a have a shape in which the central portion in the radial direction is inflated downstream. A bent portion 412b extending along the downstream end portion of the bearing surface X is provided at the downstream end portion of the main body 414a (shown by a dotted line in FIG. 65). The back foil portion Bf is provided with a flat portion 413b, an upper convex portion 413c (open circle) as a support portion, and a lower convex portion 413d (hatched circle). When the foil member 414 of FIG. 65 is attached to the foil holder 411, as shown in FIG. 66, the back foil portion Bf of each foil member 414 is hidden behind the top foil portion Tf of the adjacent foil member 414, and the top foil portion Tf Only the surface side (thrust color side) is exposed.

In the above embodiment, the case where the present invention is applied to a thrust foil bearing has been shown. However, the present invention can also be applied to a radial foil bearing that supports a shaft in a radial direction. For example, in the nineteenth embodiment shown in FIG. 67, the present invention is applied to a so-called leaf-type radial foil bearing 420. The radial foil bearing 420 includes a cylindrical foil holder 421 and a plurality of foil members 422 attached to the inner peripheral surface 421a of the foil holder 421 in a circumferential direction. Of each foil member 422, the downstream region functions as the top foil portion Tf, and the upstream region functions as the back foil portion Bf. A bent portion 412b is provided at the downstream end of the top foil portion Tf of each foil member 422, as in the above embodiment. In the back foil portion Bf (indicated by a dotted pattern), support portions (for example, upward convex portions) are provided at a plurality of locations separated in the rotation orthogonal direction (axial direction). When the shaft 402 rotates, a bearing gap C is formed between the bearing surface X of the top foil portion Tf and the outer peripheral surface of the shaft 402.

In the above embodiment, the case where the foil bearing is fixed and the shaft 402 is rotated is shown. However, the present invention is not limited thereto, and the shaft 402 may be fixed and the foil bearing may be rotated. However, if the foil bearing is rotated, the foil may be damaged by centrifugal force. Therefore, it is preferable to fix the foil bearing as in the above embodiment.

Further, the configuration of the foil bearing shown as the embodiment of the first invention and the configuration of the foil bearing shown as the embodiment of the second invention may be applied in combination.

2 shaft 3 thrust collar 10 foil bearing 11 foil holder 12 top foil 12b1 notched portion 13 back foil 13b flat portion 13c upward convex portion (first projecting portion)
13d downward protrusion (second protrusion)
Bf Back foil part Tf Top foil part X Bearing surface C Bearing gap C1 Large gap part C2 Small gap part D Foil gap E Foil bottom gap

Claims

A top foil part having a bearing surface; a back foil part that elastically supports the top foil part from behind; a foil holder to which the top foil part and the back foil part are attached; In the foil bearing that supports the shaft in a non-contact manner with the fluid pressure generated in the bearing gap between the bearing surface,
A plurality of notches are provided at the downstream end of the top foil portion,
The foil bearing which the said back foil part contacts with the said top foil part in several places spaced apart in the direction orthogonal to the relative rotation direction of an axis | shaft.
The foil bearing according to claim 1, wherein the back foil portion is in contact with the foil holder at a plurality of locations separated in a direction orthogonal to a relative rotation direction of the shaft.
The back foil portion includes a flat portion, a plurality of first protrusions protruding from the flat portion toward the top foil portion, and a plurality of second protrusions protruding from the flat portion to the opposite side of the top foil portion. The foil bearing of Claim 1 or 2 which has these.
The foil bearing according to any one of claims 1 to 3, wherein a plurality of notches are provided at a downstream end portion of the back foil portion.
The foil bearing according to claim 4, wherein a downstream end portion of the back foil portion is arranged on the downstream side of the downstream end portion of the top foil portion in the relative rotation direction.
Rigidity imparting means for forming a weir continuously provided in a direction orthogonal to the relative rotational direction by increasing the rigidity against deformation toward the side away from the shaft near the downstream end of the top foil part. The foil bearing according to any one of claims 1 to 5, wherein:
The back foil portion is provided on the downstream side of the first support portion, a first support portion that contacts and supports the top foil portion at a plurality of locations separated in a direction orthogonal to the relative rotation direction of the shaft, The foil bearing of Claim 6 which has a 2nd support part which contacts and supports a top foil part continuously in the direction orthogonal to the said relative rotation direction.
The said top foil part has the bending part bent in the area | region adjacent to the downstream of the said bearing surface along the downstream edge part of the said bearing surface to the side away from the said axis | shaft. Foil bearing.