Thrust foil air bearing with downwardly displaceable top foil leading edge

Abstract

The present invention relates to a thrust foil air bearing, which can be used in a device having a stop part and a rotating part that rotates relatively to the stop part around a center line, and includes a lower plate that is connected to the stop part so as to be immovable relative to the stop part, an intermediate plate that is arranged on the upper surface of the lower plate and has an elastically deformable bump foil, and an upper plate that is arranged on the upper surface of the intermediate plate and faces the rotating part, and has a top foil that is arranged above the bump foil and can come into contact with the rotating part, the top foil being arranged on the upstream side based on the air flow and having a front edge that is provided so as to be displaced downward toward the lower plate by air pressure generated by the rotation of the rotating part. According to the present invention, when the rotating part rotates, the air pressure generated on the upper surface of the top foil is increased, which has the effect of being able to withstand a larger load.

Description

[Technical Field]

[0001] The present invention relates to a thrust foil air bearing, and more particularly to a thrust foil air bearing that increases the air pressure generated on the upper surface of a top foil and can withstand a larger load. [Background technology]

[0002] An air bearing is a bearing that supports a load by levitating a rotating shaft using compressed air pressure between the rotating shaft and the bearing.

[0003] Such air bearings utilize the principle that when a viscous gas such as air moves along a flow surface and comes into contact with a stop surface and is compressed, the pressure of the air trapped between the flow surface and the stop surface increases, lifting the flow surface.

[0004] There are two types of air bearings: thrust air bearings, which support loads applied along the longitudinal direction of the rotating shaft, and journal air bearings, which support loads applied along the radial direction of the rotating shaft.

[0005] One type of thrust air bearing is the thrust foil air bearing, which uses a thin foil of material to further favor pressure buildup and improve dynamic stability at high speeds.

[0006] 14 shows an example of a conventional thrust foil air bearing 1, which includes a lower plate 2, which is a plate-like member connected to a stop portion S, an elastically deformable bump foil 3 arranged on the upper surface of the lower plate 2, and a top foil 4 arranged above the bump foil 3 and capable of contacting a rotating portion R. Here, the rotating portion R is connected to a rotating shaft F that rotates in a predetermined rotation direction W around a center line C.

[0007] In a conventional thrust foil air bearing 1, the bump foil 3 and top foil 4 are welded to the upper surface of the lower plate 2. Welding the bump foil 3 and top foil 4 to the lower plate 2 simplifies the overall structure of the bearing and has some advantages, such as reducing the initial product development costs and mold manufacturing costs. However, it requires multiple manufacturing processes, such as pressing and welding, and requires efforts such as manufacturing a welding jig and controlling the welding quality. As a result, it is disadvantageous in terms of product cost management and quality control, and is not suitable for mass production.

[0008] To solve the problems of the welded thrust foil air bearing 1, a thrust foil air bearing was developed in which multiple plates such as a lower plate, an intermediate plate, and an upper plate are stacked, and then slots or holes are drilled near the bearing outer frame and fixed using pins.

[0009] However, while such pin-fixed thrust foil air bearings have advantages in terms of production cost and quality control, they have problems in that they require relatively high development costs. In addition, since the lower, middle, and upper plates formed using a mold are not perfectly flat, when these plates are stacked, gaps are created between them, which increases the overall thickness of the bearing.

[0010] In addition, pin-fixed thrust foil air bearings have multiple plates fixed by multiple pins connected near the outer diameter frame of the bearing, so the outer diameter portion of the bearing is fixed relatively firmly and the plates can be closely attached to each other, but the inner diameter portion of the bearing is not fixed and is bulged, which increases the contact force with the rotating part R. As a result, pin-fixed thrust foil air bearings have problems such as increased operating torque when starting up the machine, severe bearing wear, and poor maintenance and assembly because multiple plates must be stacked.

[0011] In order to solve the above-mentioned problems, a thrust foil air bearing 1a as shown in FIG. 15 has been devised. However, the thrust foil air bearing 1a is provided in a state where it protrudes from the lower plate. The connecting portion 12a of JPEG0007779588000001.jpg10170 has an assembly structure that connects the lower plate, the middle plate, and the upper plate 30 to each other.

[0012] However, in the conventional thrust foil air bearing 1a, friction may occur between the joint portion 12a and the rotating portion R when a load is applied, and problems remain in that the joint portion 12a located between adjacent top foils 34a interferes with the air flow between the top foils 34a. Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been devised to solve the problem, and its object is to provide a thrust foil air bearing with an improved structure that increases the air pressure generated on the upper surface of the top foil and can withstand even greater loads. [Means for solving the problem]

[0014] In order to achieve the object, the thrust foil air bearing of the present invention is a thrust foil air bearing that can be used in a device having a stop portion and a rotating portion that rotates relatively to the stop portion around a center line, and includes: a lower plate that is connected to the stop portion so as to be immovable relative to the stop portion; an intermediate plate that is arranged on the upper surface of the lower plate and has an elastically deformable bump foil; and an upper plate that is arranged on the upper surface of the intermediate plate, faces the rotating portion, is arranged above the bump foil and is capable of contacting the rotating portion, and is characterized in that the top foil is arranged upstream in terms of the air flow and has a leading edge that is displaceable downward toward the lower plate by the air pressure generated by the rotation of the rotating portion.

[0015] Here, the top foil preferably comprises a top foil body and a cantilever-shaped first blade that protrudes upstream from the top foil body and is capable of elastically deforming up and down, and the leading edge is preferably provided at the front end of the first blade.

[0016] Here, it is desirable that the shape of the first blade is determined by the cooperation of an inner through hole extending circumferentially about the center line and formed inside the top foil, an outer through hole extending circumferentially about the center line and formed outside the top foil, and an intermediate through hole extending radially about the center line and connecting the inner through hole and the outer through hole.

[0017] Here, it is desirable that the leading edge has a shape that is bent downward with a predetermined first curvature.

[0018] Here, it is desirable that the lower plate be provided with a stopper that restrains the leading edge so as to limit downward elastic deformation of the leading edge to a predetermined magnitude.

[0019] Here, it is desirable that the stopper is disposed below the leading edge while passing through the intermediate plate and is capable of supporting the lower surface of the leading edge.

[0020] Here, the stopper extends in a radial direction of the centerline, It is desirable that the cross-sectional shape bent at JPEG0007779588000002.jpg10170.

[0021] Here, the stopper may include a plurality of unit stoppers arranged spaced apart from one another in the radial direction of the centerline.

[0022] Here, it is desirable that the top foil is disposed downstream with respect to the air flow and has a trailing edge having a shape bent downward with a predetermined second curvature.

[0023] Here, it is desirable that the lower plate, the intermediate plate and the upper plate have bearing mounting holes through which the bearing mounting pins pass. [Effects of the Invention]

[0024] According to the present invention, there is provided a thrust foil air bearing that can be used in a device that has a stopping part and a rotating part that rotates relative to the stopping part around a center line, the bearing including: a lower plate that is connected to the stopping part so as to be immovable relative to the stopping part; an intermediate plate that is arranged on the upper surface of the lower plate and has an elastically deformable bump foil; and an upper plate that is arranged on the upper surface of the intermediate plate, faces the rotating part, is arranged above the bump foil and is capable of contacting the rotating part, the top foil being arranged upstream in terms of the air flow and having a leading edge that is capable of being displaced downward toward the lower plate by air pressure generated by rotation of the rotating part, so that when the rotating part rotates, the air pressure generated on the upper surface of the top foil is increased, thereby having the effect of being able to withstand even greater loads. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is an assembled perspective view of a thrust foil air bearing according to one embodiment of the present invention; [Figure 2] FIG. 2 is an exploded perspective view of the thrust foil air bearing shown in FIG. 1. [Figure 3] FIG. 2 is a partially enlarged view of part III of the thrust foil air bearing shown in FIG. 1. [Figure 4] 4 is a partially enlarged view of the thrust foil air bearing shown in FIG. 3 as viewed in the direction IV. [Figure 5] FIG. 3 is a plan view of the lower plate shown in FIG. 2. [Figure 6] FIG. 3 is a plan view of the intermediate plate shown in FIG. 2. [Figure 7] FIG. 2 is a plan view of the thrust foil air bearing shown in FIG. 1. [Figure 8] 8 is a cross-sectional view of the thrust foil air bearing shown in FIG. 7 taken along line VIII-VIII during low-speed driving. [Figure 9] 8 is a cross-sectional view of the thrust foil air bearing shown in FIG. 7 taken along line VIII-VIII during high-speed driving. [Figure 10]8 is a cross-sectional view of the thrust foil air bearing shown in FIG. 7 taken along line XX during low-speed driving. [Figure 11] 8 is a cross-sectional view of the thrust foil air bearing shown in FIG. 7 taken along line XX during high-speed driving. [Figure 12] 3A and 3B are diagrams illustrating another embodiment of the lower plate illustrated in FIG. 2. [Figure 13] 13 is a cross-sectional view of the thrust foil air bearing including the lower plate shown in FIG. 12 taken along line XX. [Figure 14] FIG. 1 is a cross-sectional view showing an example of a conventional foil air bearing. [Figure 15] FIG. 10 is a perspective view showing another example of a conventional foil air bearing. DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0027] Fig. 1 is a combined perspective view of a thrust foil air bearing according to one embodiment of the present invention, and Fig. 2 is an exploded perspective view of the thrust foil air bearing shown in Fig. 1. Fig. 3 is a partially enlarged view of part III of the thrust foil air bearing shown in Fig. 1.

[0028] 1 to 3, a thrust foil air bearing 100 according to a preferred embodiment of the present invention is an air bearing that supports a load with compressed air pressure, and is a thrust bearing that can be used in a variety of devices, having a stop portion S and a rotating portion R that rotates relatively to the stop portion S about a center line C. The thrust foil air bearing 100 includes a lower plate 10, an intermediate plate 20, and an upper plate 30.

[0029] Here, as shown in Figure 14, the stopping part S and the rotating part R are circular disk members with the center line C as the center of the circle, and the rotating part R is connected to a rotating shaft F that rotates in a predetermined rotation direction W around the center line C, and multiple bearing mounting pins (not shown), which are rod members with a circular cross section that protrude in the direction of the center line C, are arranged on the upper surface of the stopping part S.

[0030] The bearing mounting pins (not shown) function to couple the lower plate 10, the intermediate plate 20 and the upper plate 30 together so that they do not rotate relative to each other on an imaginary plane intersecting the center line C.

[0031] Meanwhile, since the rotating part R is a relative term determined in the sense that it rotates relative to the stopping part S, the terms rotating part R and stopping part S may be interchangeable. However, the following description will be given on the assumption that the stopping part S is a part that stops in absolute coordinates, and the rotating part R is a part that rotates in absolute coordinates.

[0032] As shown in Figure 2, the lower plate 10 is a circular disk member manufactured by pressing a thin metal plate, and is placed on the upper surface of the stop portion S. It has a lower plate body 11, a stopper 12, and a bearing mounting hole 13.

[0033] The lower plate body 11 is a circular disk portion with the center of the circle on the center line C, and its lower surface is placed on the upper surface of the stopper portion S.

[0034] In the center of the lower plate body 11, a hollow H is formed with the center line C as the center of a circle.

[0035] The stopper 12 is a part for restraining the leading edge 35 so as to limit the downward elastic deformation of the leading edge 35 to a predetermined extent, as shown in FIGS. JPEG0007779588000003.jpg10170It has a cross-sectional shape bent.

[0036] As shown in FIG. 4, the stopper 12 protrudes from the lower plate body 11 toward the intermediate plate 20.

[0037] The stopper 12 is positioned below the leading edge 35 while passing through the first through hole 22 of the intermediate plate 20 as shown in Figure 3, and in this embodiment is arranged to support the underside of the leading edge 35.

[0038] A plurality of stoppers 12 are provided and are arranged at predetermined intervals along the circumferential direction of the center line C as shown in FIG.

[0039] The stopper 12 is disposed between the inner peripheral surface of the hollow H of the lower plate body 11 and the outer peripheral surface of the lower plate body 11. JPEG0007779588000004.jpg10170 is formed by extending the cross section in the radial direction of the center line C.

[0040] In this embodiment, the stopper 12 has a radial length that can cover almost the entire radial distance between the inner peripheral surface of the lower plate body 11 and the outer peripheral surface of the lower plate body 11 .

[0041] The stopper 12 is formed by cutting and bending the thin metal plate that filled the cutout 14, which is a hole in the lower plate body 11, by press working. Here, the circumferential length of the stopper 12 can be adjusted by appropriately cutting it, if necessary.

[0042] In this embodiment, the circumferential length or the front-rear length of the stopper 12 is long enough to support the underside of the leading edge 35, as shown in FIG. 4, but not to support the underside of the trailing edge 36, which will be described later.

[0043] In this embodiment, the upper surface of the stopper 12 is located between the lower surface of the lower plate body 11 and the upper surface of the intermediate plate 20, as shown in FIG.

[0044] The bearing mounting holes 13 are holes through which bearing mounting pins (not shown) of the stopper portion S pass, and a plurality of bearing mounting holes 13 are arranged in the circumferential direction along the frame of the lower plate main body 11.

[0045] A plurality of cooling passages 15a formed for cooling the bearings are arranged in the circumferential direction on the frame of the lower plate body 11. In this embodiment, the cooling passages 15a are formed of square grooves.

[0046] The intermediate plate 20 is a circular disk member manufactured by pressing a thin metal plate, and as shown in Figure 2, is placed on the upper surface of the lower plate 10 and comprises an intermediate plate body 21, a first through hole 22, a bearing mounting hole 23, and a bump foil 24.

[0047] The intermediate plate body 21 is a circular disk portion with the center of the circle on the center line C, and its lower surface is placed on the upper surface of the lower plate body 11. Here, the intermediate plate body 21 has the same diameter as the lower plate body 11.

[0048] A hollow H is formed in the center of the intermediate plate body 21 with the center line C as the center of a circle. Here, the hollow H of the intermediate plate body 21 has the same diameter as the hollow H of the lower plate body 11.

[0049] The first through-hole 22 is a slot-shaped hole that extends long in the radial direction of the center line C, and has a length and width that allow the stopper 12 to pass through.

[0050] The bearing mounting holes 23 are holes through which bearing mounting pins (not shown) of the stop portions S pass, and a plurality of bearing mounting holes 23 are arranged in the circumferential direction along the frame of the intermediate plate body 21.

[0051] The bearing mounting holes 23 of the intermediate plate 20 are formed at positions corresponding to the bearing mounting holes 13 of the lower plate 10, and have the same shapes.

[0052] The bump foil 24 is a part having a trapezoidal planar shape, and is a wave-like part in which a plurality of peaks and valleys are alternately connected so as to be elastically deformable in the up and down direction along a center line C.

[0053] The bump foil 24, like the stopper 12, is formed by cutting and bending the thin metal plate that fills the cutout portion 28, which is a hole in the intermediate plate body 21, by press working.

[0054] A plurality of bump foils 24 are provided and arranged at predetermined intervals along the circumferential direction of the center line C.

[0055] Of the four sides of the trapezoid, the bump foil 24 has two sides 25, 26 that are opposed to each other and spaced apart along the circumferential direction of the center line C, and only one side 25 is connected to the intermediate plate body 21, while the remaining three sides are formed as free ends.

[0056] In this embodiment, the bump foil 24 has two opposing sides that are spaced apart from each other along the circumferential direction of the center line C with respect to the air flow relative to the bump foil 24, and only the upstream side 25 of the bump foil 24 is connected to the intermediate plate body 21. In other words, only the upstream side 25 of the bump foil 24 is connected to the intermediate plate body 21, and the downstream side 26 is formed in a blade shape that is free to move.

[0057] The bump foil 24 is formed long on the downstream side along the circumferential direction of the center line C.

[0058] In this embodiment, the first through hole 22 is formed near the downstream edge 26 of two opposing edges spaced apart from each other along the circumferential direction of the center line C, and the space between the downstream edge 26 of the bump foil 24 and the intermediate plate main body 21 functions as the first through hole 22.

[0059] In this embodiment, the first through-hole 22 has a position and shape corresponding to the cutout 14 of the lower plate 10 .

[0060] In this embodiment, the bump foil 24 is disposed on the underside of a second blade 343 of the upper plate 30 (described later), but is not disposed on the underside of a first blade 342 of the upper plate 30 .

[0061] A second through-hole 27 having a parallelogram shape is formed in the middle of the upstream side 25 of the bump foil 24 .

[0062] The second through-hole 27 is a hole formed for the purpose of adjusting the elastic force of the upstream side 25 corresponding to the fixed end of the bump foil 24 .

[0063] For example, if the radial length of the second through hole 27 is increased, the elastic force of the upstream side edge 25 is reduced, and if the radial length of the second through hole 27 is decreased, the elastic force of the upstream side edge 25 is increased.

[0064] A plurality of cooling passages 15b formed for cooling the bearings are arranged in the circumferential direction on the frame of the intermediate plate body 21. In this embodiment, the cooling passages 15b have the same size and position as the cooling passages 15a.

[0065] The upper plate 30 is a circular disk member manufactured by pressing a thin metal plate, and is arranged on the upper surface of the intermediate plate 20, facing the rotating part R, and is provided with an upper plate body 31, a bearing mounting hole 33, a top foil 34, a leading edge 35, and a trailing edge 36.

[0066] The lower plate 10, the intermediate plate 20, and the upper plate 30 are made of the same metal sheet, but have different thicknesses.

[0067] The upper plate body 31 is a circular disk portion with the center of the circle on the center line C, and its lower surface is placed on the upper surface of the intermediate plate body 21. Here, the upper plate body 31 has the same diameter as the lower plate body 11.

[0068] A hollow H is formed in the center of the upper plate body 31 with the center line C as the center of a circle. Here, the hollow H of the upper plate body 31 has the same diameter as the hollow H of the lower plate body 11.

[0069] The bearing mounting holes 33 are holes through which bearing mounting pins (not shown) of the stopper portions S pass, and a plurality of bearing mounting holes 33 are arranged in the circumferential direction along the frame of the upper plate main body 31.

[0070] The bearing mounting holes 33 of the upper plate 30 are formed at positions corresponding to the bearing mounting holes 13 of the lower plate 10 and the bearing mounting holes 23 of the intermediate plate 20, and have the same shapes.

[0071] In this embodiment, the bearing mounting holes 13, 23, 33 in the lower plate 10, intermediate plate 20, and upper plate 30 are arranged on the same imaginary circumference with the center line C as the center of the circle, and are formed as semicircular grooves as shown in Figure 2, but may also be formed as circular holes.

[0072] The top foil 34 is a portion having a trapezoidal planar shape, is disposed above the bump foil 24, and is a portion that can come into contact with the rotating portion R.

[0073] A plurality of top foils 34 are provided and arranged at predetermined intervals along the circumferential direction of the center line C, and are arranged at positions corresponding to the bump foils 24, respectively.

[0074] The top foil 34, like the bump foil 24, is formed by cutting and bending a metal sheet by press working.

[0075] In this embodiment, the top foil 34 includes a top foil body 341 , a first blade 342 , and a second blade 343 .

[0076] As shown in Figure 7, the top foil body 341 is a narrow strip-shaped region extending radially along the center line C, and its inner end and outer end are fixed to the upper plate body 31.

[0077] The first blade 342 is a part that protrudes forward from the top foil main body 341 on the upstream side.

[0078] The first blade 342 has a cantilever shape with the top foil body 341 as a fixed end and the opposite end as a free end.

[0079] Therefore, the first blade 342 can be elastically deformed in the vertical direction by the air pressure generated by the rotation of the rotating part R.

[0080] The second blade 343 is a portion that protrudes rearward from the top foil main body 341 on the downstream side.

[0081] Similar to the first blade 342, the second blade 343 has a cantilever shape with the top foil body 341 as a fixed end and the opposite end as a free end.

[0082] Therefore, like first blade 342, second blade 343 has a structure that can be elastically deformed in the vertical direction by air pressure generated by rotation of rotating portion R.

[0083] However, in this embodiment, since the bump foil 24 is disposed on the lower surface of the second blade 343, unlike the first blade 342, the second blade 343 cannot be elastically deformed downward completely freely.

[0084] In this embodiment, the planar shapes of the first blade 342 and the second blade 343 are determined by the cooperation of an intermediate through-hole 32a, an inner through-hole 32b, and an outer through-hole 32c, which will be described later.

[0085] The inner through-holes 32b are arc-shaped holes extending in the circumferential direction of the center line C, and are formed inside the top foil 34, with a plurality of inner through-holes 32b arranged in the circumferential direction of the center line C.

[0086] The outer through-holes 32c are arc-shaped holes extending in the circumferential direction of the center line C, and are formed on the outside of the top foil 34, with a plurality of outer through-holes 32c being arranged in the circumferential direction of the center line C.

[0087] The intermediate through-hole 32a is a slot-shaped linear hole extending along the radial direction of the center line C, and is a hole that connects the inner through-hole 32b and the outer through-hole 32c to each other.

[0088] The intermediate through-hole 32 a is formed at a position corresponding to the first through-hole 22 of the intermediate plate 20 and the cutout 14 of the lower plate 10 .

[0089] That is, in this embodiment, the "I"-shaped through holes formed by the inner through hole 32b, the outer through hole 32c, and the intermediate through hole 32a are arranged along the circumferential direction of the center line C, thereby forming multiple top foils 34 including first blades 342 and second blades 343.

[0090] As shown in FIG. 3, the leading edge 35 is a leading edge provided at the front end of the first blade 342, and is a portion similar to the leading edge of an airfoil.

[0091] In this embodiment, the leading edge 35 has a shape that is bent downward with a predetermined first curvature R1, as shown in Figure 4. Here, the center of curvature of the leading edge 35 is located below the upper plate 30.

[0092] 8, when the rotating part R rotates in the rotation direction W, air pressure P1 is generated on the upper surface of the top foil 34 due to the rotation, and the first blade 342 is elastically deformed downward by the air pressure P1, so that the leading edge 35 hangs down by a predetermined height h1 toward the lower plate 10. At this time, the stopper 12 and the lower surface of the leading edge 35 do not contact each other.

[0093] Furthermore, when the rotation speed of the rotating part R becomes higher than a predetermined value, the air pressure P2 generated on the upper surface of the top foil 34 also increases further, causing the leading edge 35 to hang down by an even greater height h2 toward the lower plate 10, as shown in Figure 9. At this time, the stopper 12 supports the lower surface of the leading edge 35, thereby restricting the leading edge 35 from moving downward beyond the predetermined height.

[0094] As shown in FIG. 3, the trailing edge 36 is a trailing edge provided at the trailing end of the second blade 343, and is a portion similar to the trailing edge of an airfoil.

[0095] In this embodiment, the trailing edge 36 has a shape that is bent downward with a predetermined second curvature R2, as shown in Figure 4. Here, the center of curvature of the trailing edge 36 is located below the upper plate 30.

[0096] However, in this embodiment, the bump foil 24 supports and restrains the underside of the second blade 343, so even if the rotation speed of the rotating part R becomes relatively high, the trailing edge 36 moves downward very little.

[0097] A plurality of cooling passages 15c formed for cooling the bearings are arranged in the circumferential direction on the frame of the upper plate body 31. In this embodiment, the cooling passages 15c have the same size and position as the cooling passages 15a and 15b.

[0098] In this embodiment, the cooling passages 15a, 15b, 15c of the lower plate 10, the intermediate plate 20 and the upper plate 30 cooperate to form the cooling passage 15 of the thrust foil air bearing 100 as shown in FIG.

[0099] An example of the principle of operation of the thrust foil air bearing 100 having the above-described configuration will now be described.

[0100] 8, when the rotating part R rotates at a relatively low speed, a relatively small amount of air pressure P1 is generated on the upper surface of the top foil 34 due to the rotation of the rotating part R, and the first blade 342 is elastically deformed downward by the air pressure P1 to a relatively small size, causing the leading edge 35 to sag slightly by a predetermined height h1. At this time, the stopper 12 and the lower surface of the leading edge 35 do not contact each other, and the elastic force of the first blade 342 and the air pressure P1 are balanced.

[0101] When the rotating part R is driven at a relatively low speed, a relatively small air pressure P1 is generated on the upper surface of the top foil 34, and the air pressure P3 generated on the upper surface of the leading edge 35 has a relatively uniform and small value, as shown in Figure 10.

[0102] 9, when the rotating part R rotates at a relatively high speed, a relatively large air pressure P2 is generated on the upper surface of the top foil 34 due to the rotation of the rotating part R, and the first blade 342 is elastically deformed downward by a relatively large size due to the air pressure P2, so that the leading edge 35 hangs down by a relatively large height h2. At this time, the stopper 12 supports the lower surface of the leading edge 35, thereby restricting the leading edge 35 from moving further downward.

[0103] When the rotating part R is driven at a relatively high speed, a relatively large air pressure P2 is generated on the upper surface of the top foil 34, and the air pressure P4 generated on the upper surface of the leading edge 35 has a relatively uniform and large value, as shown in Figure 11.

[0104] On the other hand, since the bump foil 24 firmly supports and restrains the lower surface of the second blade 343 as a whole, the trailing edge 36 hardly sags regardless of the rotation speed of the rotating part R.

[0105] The thrust foil air bearing 100 configured as described above is a thrust foil air bearing that can be used in a device that has a stop portion S and a rotating portion R that rotates relative to the stop portion S about a center line C, and includes a lower plate 10 that is connected to the stop portion S so as to be immovable relative to it, an intermediate plate 20 that is arranged on the upper surface of the lower plate 10 and has an elastically deformable bump foil 24, an upper plate 30 that is arranged on the upper surface of the intermediate plate 20, faces the rotating portion R, is arranged above the bump foil 24, and has a top foil 34 that can come into contact with the rotating portion R, and the top foil 34 is arranged upstream in terms of the air flow and has a leading edge 35 that is displaceable downward toward the lower plate 10 by the air pressure generated by the rotation of the rotating portion R. Therefore, when the rotating portion R rotates, the air pressures P1 and P2 generated on the upper surface of the top foil 34 increase, which has the advantage of being able to withstand even greater loads.

[0106] In the thrust foil air bearing 100, the top foil 34 comprises a top foil main body 341 and a cantilever-shaped first blade 342 that protrudes upstream from the top foil main body 341 and is elastically deformable up and down, and the leading edge 35 is provided at the front end of the first blade 342, which has the advantage that the elastic sagging of the leading edge 35 can be easily realized and the elastic coefficient of the first blade 342 can be easily adjusted taking into account the rotational speed of the rotating part R.

[0107] In addition, the thrust foil air bearing 100 has a first blade 342 that extends circumferentially about the center line C and whose shape is determined by the cooperation of the inner through hole 32b formed on the inside of the top foil 34, the outer through hole 32c that extends circumferentially about the center line C and is formed on the outside of the top foil 34, and the intermediate through hole 32a that extends radially about the center line C and connects the inner through hole 32b and the outer through hole 32c, so it has the advantage that the first blade 342 can be easily formed using press processing.

[0108] Furthermore, since the thrust foil air bearing 100 has a leading edge 35 that is bent downward at a predetermined first curvature R1, it has the advantage of further accelerating the formation of air pressures P1 and P2 on the upper surface of the top foil 34 compared to when the leading edge 35 does not have a curvature.

[0109] Furthermore, the thrust foil air bearing 100 has a lower plate 10 provided with a stopper 12 that restrains the leading edge 35 so as to limit the downward elastic deformation of the leading edge 35 to a predetermined amount. This prevents excessive sagging of the leading edge 35, thereby enabling efficient generation of air pressures P1 and P2 and preventing the leading edge 35 from colliding with other components and generating noise and wear.

[0110] Furthermore, in the thrust foil air bearing 100, the stopper 12 is positioned below the leading edge 35 while penetrating the intermediate plate 20, and is capable of supporting the underside of the leading edge 35, which has the advantage that the stopper 12 can be easily formed using press processing.

[0111] In addition, the thrust foil air bearing 100 has a stopper 12 extending in the radial direction of the center line C, JPEG0007779588000005.jpg10170 has a bent cross-sectional shape, which increases the contact area between the lower surface of the leading edge 35 and the stopper 12, thereby preventing the lower surface of the leading edge 35 from being damaged.

[0112] In addition, in the thrust foil air bearing 100, the top foil 34 is disposed downstream with respect to the air flow and has a trailing edge 36 that is bent downward at a predetermined second curvature R2, so that the air flowing over the upper surface of the top foil 34 is smoothly separated from the trailing edge 36 of the top foil 34, which has the advantage of preventing the generation of vortexes in the air flow. Such vortexes could have a negative aerodynamic effect in relation to the trailing top foil 34.

[0113] Furthermore, the thrust foil air bearing 100 has bearing mounting holes 13, 23, 33 through which bearing mounting pins (not shown) pass in the lower plate 10, intermediate plate 20, and upper plate 30, which are relatively easy to procure and have a high structural strength. This has the advantage that the bearing can be easily attached to the stopper S by simply stacking the lower plate 10, intermediate plate 20, and upper plate 30 in order using bearing mounting pins (not shown).

[0114] 12 shows a lower plate 10a, which is another embodiment of the lower plate 10. The lower plate 10a differs from the lower plate 10 in that, instead of having one long stopper 12, the lower plate 10a has a plurality of unit stoppers 121 spaced apart from one another in the radial direction of the center line C.

[0115] The width W1 and the separation distance L1 of the unit stopper 121 are appropriately determined in consideration of the thickness and elasticity of the top foil 34.

[0116] Use of the above-described lower plate 10a has the advantage that, assuming the rotational speed of the rotating part R is the same, the value of the air pressure P5 generated on the upper surface of the leading edge 35 as shown in Figure 13 is greater than the air pressure P4 as shown in Figure 11. This is because, unlike when the stopper 12 is used, the droop of the middle part of the leading edge 35 is slightly greater than the droop of both ends of the leading edge 35 as shown in Figure 13.

[0117] In the above-described embodiment, only one upper plate 30, one lower plate 10 and one intermediate plate 20 are attached, but it goes without saying that two or more of at least one of the upper plate 30, the lower plate 10 and the intermediate plate 20 can be attached.

[0118] In the above-described embodiment, the leading edge 35 and the trailing edge 36 are described as having one center of curvature, but the leading edge 35 and the trailing edge 36 may have multiple centers of curvature and may include curved surfaces with complex shapes.

[0119] Although the present invention has been described above, the technical scope of the present invention is not limited to the contents described in the above-mentioned embodiments, and it is clear that equivalent configurations modified or changed by a person having ordinary knowledge in the art do not depart from the technical idea of ​​the present invention.

Claims

1. 1. A thrust foil air bearing usable in an apparatus having a stop portion and a rotating portion that rotates relative to the stop portion about a centerline, a lower plate connected to the stop portion so as not to move relative to the stop portion; an intermediate plate disposed on an upper surface of the lower plate and having an elastically deformable bump foil; an upper plate disposed on an upper surface of the intermediate plate, facing the rotating portion, and including a top foil disposed above the bump foil and capable of contacting the rotating portion; the top foil is disposed upstream with respect to the air flow, and includes a leading edge that is displaceable downward toward the lower plate by air pressure generated by rotation of the rotating part, the top foil includes a top foil body and a cantilever-shaped first blade that protrudes from the top foil body toward the upstream side and is elastically deformable up and down, 2. A thrust foil air bearing, comprising: a first blade having a leading edge and a leading end portion, the ...

2. The first blade is an inner through hole extending along a circumferential direction of the center line and formed inside the top foil; an outer through hole extending along a circumferential direction of the center line and formed on the outer side of the top foil; 2. The thrust foil air bearing according to claim 1, wherein the shape is determined by cooperation with an intermediate through hole extending radially along the center line and connecting the inner through hole and the outer through hole.

3. The thrust foil air bearing of claim 1 , wherein the leading edge (12) has a downwardly folded shape with a first predetermined curvature.

4. 2. The thrust foil air bearing according to claim 1, wherein the lower plate is provided with a stopper that restrains the leading edge so as to limit downward elastic deformation of the leading edge to a predetermined magnitude.

5. 5. The thrust foil air bearing according to claim 4, wherein the stopper is disposed below the leading edge while passing through the intermediate plate, and is capable of supporting a lower surface of the leading edge.

6. The stopper extends in a radial direction of the centerline, 5. The thrust foil air bearing according to claim 4, wherein the bearing has a cross-sectional shape bent in a direction perpendicular to the axis of the foil.

7. 5. The thrust foil air bearing according to claim 4, wherein the stopper comprises a plurality of unit stoppers arranged spaced apart from one another in the radial direction of the centerline.

8. 2. The thrust foil air bearing according to claim 1, wherein the top foil is disposed downstream relative to the air flow and has a trailing edge having a shape bent downward with a predetermined second curvature.

9. 2. The thrust foil air bearing according to claim 1, wherein the lower plate, the intermediate plate, and the upper plate are provided with bearing mounting holes through which bearing mounting pins pass.

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