Foil air bearing with herringbone pattern

Abstract

The present invention relates to a foil air bearing having a herringbone pattern and corresponding to a foil air bearing for supporting the weight of a rotating part rotating in a predetermined rotational direction about a center line, the foil air bearing including: an upper top foil disposed to face a surface of the rotating part; a middle top foil disposed below the upper top foil; a lower top foil disposed below the middle top foil; a wave foil as an elastically deformable member and disposed below the lower top foil; and a plurality of slots extending through an upper surface of the middle top foil to a lower surface of the middle top foil and extending in a longitudinal direction having a predetermined angle with respect to the rotational direction of the rotating part, wherein the upper top foil is concavely deformed downward at positions corresponding to the slots by aerodynamic pressure generated by rotation of the rotating part, so that a herringbone pattern is formed.

Description

Technical Field

[0001] This invention relates to a foil air bearing, and more particularly to a foil air bearing capable of easily forming a herringbone pattern to meet design requirements and reducing overall manufacturing costs by forming slots through stamping without the use of etching or welding. Background Technology

[0002] Air bearings are bearings used to maintain load by increasing the pressure of the rotor using compressed air between the rotor and the bearing.

[0003] Air bearings are used when a viscous gas, such as air, moves along with a moving surface and then compresses upon encountering a stationary surface. The pressure of the air trapped between the moving and stationary surfaces increases, thereby lifting the moving surface.

[0004] Air bearings include thrust air bearings for maintaining loads applied along the longitudinal direction of the rotor, and journal air bearings for maintaining loads applied along the radial direction of the rotor.

[0005] As a type of journal air bearing, journal foil air bearings use thin foil to easily generate pressure and increase dynamic stability at high speeds.

[0006] Figure 12 An example of a journal foil air bearing 1 is shown. The journal foil air bearing 1 includes a top foil 2, disposed facing the outer circumferential surface of a rotor F having a circular rotating shaft shape that rotates in a predetermined rotational direction W and surrounds the rotor F; and a corrugated foil 3, configured as an elastically deformable corrugated member and disposed to surround the top foil 2, with one end of the top foil 2 and the corrugated foil 3 welded to a welded portion 4 inside the bearing housing S.

[0007] At the same time, such as Figure 15 As shown, the existing thrust foil air bearing 1a includes: a lower plate 2a, which is provided as a plate-shaped member connected to a stop member S; a corrugated foil 3a, which is disposed on the upper surface of the lower plate 2a and is elastically deformable; and a top foil 4a, which is disposed on the corrugated foil 3a and is capable of contacting a rotor R having a circular rotating plate shape. In this document, the rotor R is connected to a rotor F having a circular rotating shaft shape that rotates about a centerline C in a predetermined rotational direction W.

[0008] Air bearing 1 or air bearing 1a lifts rotor F or rotor R in a non-contact manner by using pressure generated inside the bearing due to the rotational speed of rotor F or rotor R, and in this case, the value of the pressure generated inside the bearing is reduced due to the outflow U generated towards both sides of the bearing, such as Figure 13 As shown in the text. Figure 13 This is a development view of the top foil 2 of the journal foil air bearing 1 when it is unfolded in the rotational direction W.

[0009] like Figure 14 The pressure leakage observed at the bearing ends (e.g., x = 0 and x = L) reduces the internal pressure of the bearing and thus decreases its load capacity and performance. In this paper, Figure 14 A diagram showing the air pressure distribution inside the journal foil air bearing 1 based on the location of the top foil 2 in the lateral direction (e.g., the x direction) when the top foil 2 is unfolded in the rotational direction W.

[0010] To address the above problems, U.S. Patent Publication No. 20150362012, published on December 17, 2015, discloses a foil air bearing that utilizes an additional foil inserted between a top foil and a corrugated foil; forms a groove with a bottom by etching or machining the upper surface of the additional foil; and deforms the upper surface of the top foil due to air pressure (e.g., ...). Figure 6 As shown, a so-called herringbone pattern is formed to achieve a herringbone effect, creating an inflow U on the upper surface of the top foil, such as... Figure 7 As shown in the figure.

[0011] However, according to existing foil air bearings, the overall manufacturing cost increases and the product quality decreases because the etching or machining process used to form grooves on the upper surface of the additional foil is technically extremely difficult.

[0012] In addition, according to existing foil air bearings, since the bottom groove is formed on the additional foil, when the groove does not have sufficient depth, the bottom of the groove hinders the deformation of the top foil and therefore does not form a herringbone pattern that meets the design requirements. Summary of the Invention

[0013] Technical difficulties

[0014] The present invention provides a foil air bearing that can be easily formed into a herringbone pattern to meet design requirements and reduces overall manufacturing costs by forming slots by stamping without using etching or welding.

[0015] Technical solutions

[0016] According to an aspect of the invention, a foil air bearing is provided for maintaining a load on a rotor rotating about a centerline in a predetermined rotational direction. The foil air bearing comprises: an upper top foil disposed facing the rotor; a middle top foil disposed below the upper top foil; a lower top foil disposed below the middle top foil; a corrugated foil disposed as an elastically deformable member below the lower top foil; and a plurality of slots; and holes provided as holes extending from the upper surface of the middle top foil to the lower surface and along a longitudinal direction forming a predetermined angle with the rotational direction of the rotor, wherein the upper top foil deforms into a downwardly concave shape at locations corresponding to the slots due to air pressure generated by the rotation of the rotor, thereby forming a herringbone pattern.

[0017] Multiple slots can be spaced apart by a predetermined distance and arranged symmetrically with respect to a virtual symmetry line parallel to the direction of rotation.

[0018] Top foil and corrugated foil can have shapes that can be mass-produced by automatically cutting and bending through stamping without the use of etching or welding.

[0019] The lower surface of the middle top foil and the upper surface of the lower top foil can be stacked on top of each other in a separable state.

[0020] The foil air bearing may include a journal foil air bearing, wherein the rotor is arranged in the form of a rotating shaft, and the journal foil air bearing may include: a base foil arranged to surround a corrugated foil; and a coupling for connecting one end of a plurality of top foils, one end of the corrugated foil and two ends of the base foil to each other.

[0021] The foil air bearing may include a journal foil air bearing, wherein the rotor is configured as a rotating shaft, and as the rotor rotates, the slots are more densely packed near the upper top foil than at other locations.

[0022] The foil air bearing may include a thrust foil air bearing, wherein the rotor is arranged in the form of a rotating plate, the central top foil is arranged in the form of a circular plate, and the slot is arranged along a virtual circle having a center line as the center of the circle.

[0023] Beneficial effects

[0024] According to the present invention, a foil air bearing for maintaining a load on a rotor rotating about a centerline in a predetermined rotational direction comprises: an upper top foil disposed facing the rotor; a middle top foil disposed below the upper top foil; a lower top foil disposed below the middle top foil; a corrugated foil disposed as an elastically deformable member below the lower top foil; and a plurality of slots; and holes provided as penetrations from the upper surface of the middle top foil to the lower surface and extending along a longitudinal direction forming a predetermined angle with the rotational direction of the rotor, wherein the upper top foil deforms into a downwardly concave shape at locations corresponding to the slots due to air pressure generated by the rotation of the rotor, thereby forming a herringbone pattern. Therefore, a herringbone pattern meeting design requirements can be easily formed, and the overall manufacturing cost can be reduced by forming the slots by stamping without etching or welding. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view of a journal foil air bearing according to an embodiment of the present invention.

[0026] Figure 2 yes Figure 1 The exploded perspective view of the journal foil air bearing shown.

[0027] Figure 3 yes Figure 1 A magnified view of part A.

[0028] Figure 4 yes Figure 2 The development view of the central top foil is shown.

[0029] Figure 5 yes Figure 1 The diagram shows the development of the journal foil air bearing.

[0030] Figure 6 It is along Figure 5 A cross-sectional view taken from line VI-VI.

[0031] Figure 7 It is shown that it is attributed to Figure 1 The development view shown depicts the flow pattern on the top foil of the journal foil air bearing, where a herringbone effect appears.

[0032] Figure 8 Different types of center top foil are shown.

[0033] Figure 9 This is an exploded perspective view of a thrust foil air bearing according to another embodiment of the present invention.

[0034] Figure 10 yes Figure 9 The diagram shows a plan view of the thrust foil air bearing.

[0035] Figure 11 It is along Figure 10 A cross-sectional view taken by line XI-XI.

[0036] Figure 12 This is a cross-sectional view of an existing journal foil air bearing.

[0037] Figure 13 It is used to describe air pressure attributed to direction. Figure 12 The development view shown is of the reduced flow U generated on both sides of the top foil of the journal foil air bearing.

[0038] Figure 14 It is shown Figure 12 The diagram shows the air pressure distribution inside the journal foil air bearing.

[0039] Figure 15 This is a cross-sectional view of an existing thrust foil air bearing.

[0040] Explanation of icon numbers

[0041] 1. 100: Journal foil air bearing;

[0042] 1a, 200: Thrust foil air bearing;

[0043] 2, 4a: Top foil;

[0044] 2a: Lower plate;

[0045] 3, 3a, 20, 220: Corrugated foil;

[0046] 4: Welding parts;

[0047] 10, 210: Substrate foil;

[0048] 30, 230: upper top foil;

[0049] 40, 40a, 40b, 40c, 40d, 40e, 240: Middle top foil;

[0050] 41: Slot;

[0051] 50, 250: lower top foil;

[0052] 60: Connecting component;

[0053] A: Partial;

[0054] C: Centerline;

[0055] d: width;

[0056] F: Rotor;

[0057] H: Hollow;

[0058] M: Air guide groove;

[0059] R: Rotor / rotating plate;

[0060] S: Bearing housing;

[0061] U: Outflow / Inflow;

[0062] VI-VI, XI-XI: lines;

[0063] W: Predetermined rotation direction;

[0064] Y: Line of symmetry;

[0065] θ: Predetermined angle. Detailed Implementation

[0066] The present invention will be described in detail below by referring to the accompanying drawings and explaining embodiments thereof.

[0067] Figure 1 This is a cross-sectional view of the journal foil air bearing 100 according to an embodiment of the present invention, and Figure 2 yes Figure 1 The exploded perspective view of the journal foil air bearing 100 shown. Figure 3 yes Figure 1 An enlarged view of part A shown in the image.

[0068] refer to Figures 1 to 3 According to an embodiment of the present invention, the journal foil air bearing 100 is used to maintain a position along the axis as shown in the figure. Figure 12 The rotor shown is in the form of a rotating shaft F with a circular cross-section, subjected to a radial load via a journal foil air bearing, and includes a base foil 10, a corrugated foil 20, an upper top foil 30, a middle top foil 40, a lower top foil 50, and a connecting member 60. The following description assumes the rotor rotates around... Figure 1 The centerline C shown rotates in a predetermined rotation direction W.

[0069] The base foil 10 is a circular pipe component formed by stamping a flexible and elastic metal sheet, such as... Figure 2 As shown in the figure.

[0070] In the current embodiment, the substrate foil 10 is produced in the form of a tube with a “C” shaped cross-section by rolling a stamped rectangular metal sheet around a center line C.

[0071] The base foil 10 is a circular pipe member extending a predetermined length along the center line C, and includes a hollow H with the center line C as the center of the circle.

[0072] The substrate foil 10 is arranged to surround the corrugated foil 20, which will be described below, such that the corrugated foil 20 is contained within the hollow H of the substrate foil 10.

[0073] The two ends of the base foil 10 are bent in an "L" shape and protrude upwards, such as Figure 3 As shown in the figure, it can be connected to the connector 60.

[0074] Corrugated foil 20 is a circular pipe component formed by stamping flexible and elastic metal sheets, such as... Figure 2 As shown in the figure.

[0075] The corrugated foil 20 is a circular pipe component extending a predetermined length along the center line C, and includes a hollow H with the center line C as the center of the circle.

[0076] In the current embodiment, the corrugated foil 20 is made in the form of a tube with a "C" shaped cross-section by rolling a stamped rectangular metal sheet around a center line C.

[0077] The corrugated foil 20 is arranged to surround the lower top foil 50 and is contained within the hollow H of the base foil 10.

[0078] The corrugated foil 20 includes a wavy section in which multiple peaks and valleys are alternately connected, thereby enabling it to elastically deform in the radial direction of the centerline C.

[0079] The right end of the corrugated foil 20 is curved in an "L" shape and protrudes upward, as shown in the image. Figure 3 As shown in the figure, it can be connected to the connector 60.

[0080] The left end of the corrugated foil 20 is a freely movable end, such as... Figure 1 As shown in the figure.

[0081] In the current embodiment, a pair of corrugated foils 20 are provided and stacked one on top of the other, such as Figure 3 As shown in the figure.

[0082] The upper top foil 30 is a circular pipe component formed by stamping a flexible and elastic metal sheet, such as... Figure 2 As shown, and placed at the innermost position (e.g.) Figure 3 As shown in the figure, so that it faces the outer circumferential surface of the rotation axis F.

[0083] The upper foil 30 is a circular pipe member extending a predetermined length along the center line C, and includes a hollow H with the center line C as the center of the circle.

[0084] In the current embodiment, each of the upper top foil 30, the middle top foil 40, and the lower top foil 50 is formed into a tube with a "C" shaped cross-section by rolling a stamped rectangular metal sheet around the center line C.

[0085] The upper foil 30 is arranged to surround the rotating shaft F and is also housed in the hollow H of the corrugated foil 20.

[0086] A connecting piece 60, which is bent in the shape of a "∩", is provided at the left end of the upper top foil 30.

[0087] The right end of the upper top foil 30 is a freely movable end, such as... Figure 3 As shown in the figure.

[0088] The outer circumferential surface of the upper top foil 30 facing the rotation axis F is coated with a coating material containing polytetrafluoroethylene (PTFE) (not shown). PTFE is also known as Teflon.

[0089] The upper top foil 30 has a pressure that allows the upper top foil 30 to be attributed to the air pressure generated by the rotation of the rotating shaft F, and in accordance with... Figure 6 The location of the slot 41 shown is deformed into a downward concave shape, thereby forming a shape as shown in the figure. Figure 5 The material and thickness shown are those of a herringbone pattern with multiple air guide grooves M.

[0090] When the thickness of the upper foil 30 is too large, the herringbone pattern may not form a sufficient depth.

[0091] Similar to the upper top foil 30, the middle top foil 40 is a circular pipe member extending a predetermined length along the center line C, and includes a hollow H with the center line C as the center of the circle.

[0092] The middle top foil 40 is arranged to surround the upper top foil 30 and is also contained in the hollow H of the lower top foil 50, which will be described below.

[0093] The right end of the central top foil 40 is curved in an "L" shape and protrudes upwards, as... Figure 3 As shown in the figure, it can be connected to the connector 60.

[0094] The left end of the central top foil 40 is a freely movable end, such as... Figure 3 As shown in the figure.

[0095] In the central top foil 40, multiple slots 41 are provided, such as Figure 4 As shown in the figure.

[0096] The slot 41 is a hole penetrating from the upper surface of the central top foil 40 to the lower surface, and is symmetrically arranged with respect to the imaginary line of symmetry Y parallel to the rotation direction W of the rotation axis F, such as... Figure 4 As shown in the figure.

[0097] Slot 41 is as follows Figure 4 The planar parallelogram shape shown has the following characteristics: Figure 5 The diagram shows a strip-shaped hole of a certain width d that extends along the longitudinal direction.

[0098] The slot 41 extends along a longitudinal direction that forms a predetermined angle θ with respect to the line of symmetry Y of the rotation direction W parallel to the rotation axis F.

[0099] Angle θ is an acute angle less than 90°, and its value can vary as needed. In the current embodiment, angle θ is 45°.

[0100] Multiple slots 41 are spaced apart from each other by a predetermined distance along the line of symmetry Y.

[0101] Ultimately, due to the slot 41, the central top foil 40 has such Figure 4 The herringbone pattern shown is illustrated.

[0102] In this article, "herringbone" refers to the skeleton of a fish called a herring, and a herring pattern is a design or pattern in which multiple fishbone or arrow shapes are arranged close together.

[0103] The central top foil 40 can be processed by wire cutting, drilling, or water jet cutting.

[0104] In the current embodiment, the central top foil 40 has a thickness of less than or equal to 0.2 mm.

[0105] at the same time, Figure 8 The central top foil 40a to central top foil 40e are shown, each with a different herringbone pattern.

[0106] The middle top foil 40a and the middle top foil 40b include slots 41 with closed ends, and the middle top foil 40c, the middle top foil 40d and the middle top foil 40e include slots 41 with open ends.

[0107] In particular, the central top foil 40c has a shape in which the width d of a certain portion of the slot 41 is smaller than the width of the other slots 41 and the distance between the slots 41 in a certain portion is smaller than the distance between the other slots 41.

[0108] Generally, in a journal foil air bearing 100, when the rotating shaft F rotates, the distance between the rotating shaft F and the upper top foil 30 depends on, for example... Figure 12 The location varies as shown. That is, the lower part of the rotation axis F is very close to the upper top foil 30, and the upper part of the rotation axis F is very far away from the upper top foil 30.

[0109] Therefore, when using the middle top foil 40c, at a location where the rotation axis F is relatively close to the upper top foil 30, that is, at Figure 8In the middle portion of the top foil 40c, the slots 41 can be arranged more closely together or with a smaller spacing to have a smaller width d of the slots 41 and a smaller distance between the slots 41 compared to other locations. Therefore, the lubrication effect can be improved by increasing the air flow U at the lower portion of the rotating shaft F.

[0110] In the current embodiment, the central top foil 40 has a similar shape to... Figure 8 The structure of the central top foil 40d shown is illustrated.

[0111] Slot 41 can be set in such a way as Figure 4 The central top foil 40 shown is positioned above or above the entire length of the foil. Figure 8 Above only a portion of the length of the middle top foil 40c and the middle top foil 40d.

[0112] Similar to the upper top foil 30, the lower top foil 50 is a circular pipe component extending a predetermined length along the center line C, and includes a hollow H with the center line C as the center of the circle.

[0113] The lower top foil 50 is arranged to surround the middle top foil 40 and is contained in the hollow H of the corrugated foil 20.

[0114] The left end of the lower top foil 50 is curved in an "L" shape and protrudes upwards, as shown in the image. Figure 3 As shown in the figure, it can be connected to the connector 60.

[0115] The right end of the lower top foil 50 is a freely movable end, such as... Figure 3 As shown in the figure.

[0116] Since the lower top foil 50 is used to support the middle top foil 40, the thickness of the lower top foil 50 can be greater than the thickness of the middle top foil 40.

[0117] In the current embodiment, the lower surface of the middle top foil 40 and the upper surface of the lower top foil 50 are not joined to each other by welding or the like, and are simply stacked on top of each other in a separable state.

[0118] Therefore, as Figure 6 As shown in the cross-sectional view of the journal foil air bearing 100, a stacked structure is formed in which a middle top foil 40 is disposed below an upper top foil 30, a lower top foil 50 is disposed below a middle top foil 40, a corrugated foil 20 is disposed below a lower top foil 50, and a base foil 10 is disposed below a corrugated foil 20.

[0119] The base foil 10, the corrugated foil 20, and the top foil 30, top foil 40, and top foil 50 can be formed from metal sheets made of the same material but with different thicknesses.

[0120] In the current embodiment, the top foil 30, top foil 40, and top foil 50, the corrugated foil 20, and the base foil 10 have shapes that can be mass-produced by automatically cutting and bending by stamping without the use of etching or welding.

[0121] Connector 60 is a component used to connect one end of a plurality of top foils 30, 40, and 50, one end of the corrugated foil 20, and both ends of the base foil 10 to each other, such as Figure 3 As shown in the figure.

[0122] Although not shown in detail, but as Figure 3 As shown, the connector 60 includes connector holes (not shown) disposed at both ends of the base foil 10 and at one end of the corrugated foil 20, top foil 30, top foil 40 and top foil 50, and connector members (not shown) fixed through the connector holes (not shown).

[0123] In the current embodiment, the connecting member (not shown) is inserted into the connecting hole (not shown) and then bent and plastically deformed at both ends to secure the top foil 30, top foil 40, and top foil 50, the corrugated foil 20, and the base foil 10 to each other. Shaped sheet components.

[0124] An example describing the operating principle of the aforementioned journal foil air bearing 100 will now be presented.

[0125] Initially, when the rotating shaft F begins to rotate, a portion of the upper top foil 30 deforms into a downward concave shape due to the air pressure generated by the rotation of the rotating shaft F, such as... Figure 6 As shown, and thus a herringbone pattern with multiple air guiding grooves M is formed on the upper surface of the upper top foil 30, such as... Figure 5 As shown in the figure.

[0126] When the air guiding groove M described above is formed, air flows into U from the symmetrical line Y in the middle of the upper surface of the upper top foil 30, diagonally from both sides of the upper top foil 30. Figure 7 As shown, and thus prevents pressure leakage on both sides of the bearing, a herringbone effect occurs, such as... Figure 14 As shown in the figure.

[0127] The aforementioned journal foil air bearing 100 is a foil air bearing used to maintain the load of a rotor F rotating about a centerline C in a predetermined rotational direction. It includes an upper top foil 30, positioned facing the rotor F; a middle top foil 40, positioned below the upper top foil 30; a lower top foil 50, positioned below the middle top foil 40; a corrugated foil 20, configured as an elastically deformable member and positioned below the lower top foil 50; and a plurality of slots 41, configured as holes extending from the upper surface of the middle top foil 40 to the lower surface and along a longitudinal direction forming a predetermined angle θ with the rotational direction W of the rotor F. Due to the air pressure generated by the rotation of the rotor F, the upper top foil 30 deforms into a downwardly concave shape at locations corresponding to the slots 41, thereby forming a herringbone pattern. Therefore, a herringbone pattern meeting design requirements can be easily formed, and the overall manufacturing cost can be reduced by forming the slots 41 by stamping without etching or welding.

[0128] According to the journal foil air bearing 100, since the plurality of slots 41 are spaced apart from each other by a predetermined distance and are arranged symmetrically with respect to the imaginary symmetry line Y parallel to the rotation direction W, pressure leakage from both sides of the bearing can be reduced and thus the load capacity and performance of the bearing can be improved.

[0129] According to the journal foil air bearing 100, since the top foil 30, top foil 40, and top foil 50 and the corrugated foil 20 have shapes that can be mass-produced by automatically cutting and bending by stamping without using etching or welding, the overall manufacturing cost and manufacturing time can be reduced.

[0130] According to the journal foil air bearing 100, since the lower surface of the middle top foil 40 and the upper surface of the lower top foil 50 are stacked on each other in a separable state, unlike general journal foil air bearings that include a groove with a bottom, the middle top foil 40 can be selectively repaired or replaced after long-term use.

[0131] According to the journal foil air bearing 100, since it includes a connector 60 for connecting one end of a plurality of top foils 30, top foil 40 and top foil 50, one end of corrugated foil 20 and two ends of base foil 10 to each other, the journal foil air bearing 100 can be configured as a “modular” bearing that can be easily inserted into a bearing housing.

[0132] In the current embodiment, the connector 60 includes a configuration as... The sheet member includes connecting members (not shown) and connecting holes (not shown) provided at both ends of the base foil 10 and at one end of the corrugated foil 20, top foil 30, top foil 40 and top foil 50, but may also include any connecting device.

[0133] at the same time, Figure 9A thrust foil air bearing 200 according to another embodiment of the present invention is shown. The thrust foil air bearing 200 is in which a rotor rotating about a centerline C is arranged as follows: Figure 15 The circular rotating plate R shown is in the form of a base foil 210, a bottom foil 210, a foil 220, a wave foil 220, an upper foil 230, a top foil 230, a middle foil 240, a top foil 240, and a lower foil 250, a top foil 250, and a thrust foil air bearing.

[0134] The configuration and effect of the thrust foil air bearing 200 and the journal foil air bearing 100 are largely similar, and therefore only the differences between the two will be described here.

[0135] The thrust foil air bearing 200 differs from the journal foil air bearing 100 in that foils 210, 220, 230, 240, and 250 are arranged in the form of hollow circular plates.

[0136] The difference between the thrust foil air bearing 200 and the journal foil air bearing 100 is that the middle foil 240 and the top foil 240 are arranged in the form of a circular plate and the slot 41 is arranged along a virtual circle Y with the center line C as the center of the circle.

[0137] However, as Figure 11 As shown, the cross-sectional structure of the thrust foil air bearing 200 is similar to... Figure 6 The cross-sectional structure of the journal foil air bearing 100 shown is almost identical.

[0138] Therefore, according to the thrust foil air bearing 200, due to the air pressure generated by the rotation of the rotating plate R, the upper foil 230 can deform into a downward concave shape at the location corresponding to the slot 41, such as... Figure 11 As shown, this forms a herringbone pattern with multiple air guide grooves M.

[0139] Although the invention has been shown and described with specific reference to embodiments thereof, those skilled in the art will understand that various changes to the form and details of the invention may be made without departing from the scope of the invention as defined by the appended claims.

Claims

1. A foil air bearing for maintaining a load on a rotor rotating about a centerline in a predetermined rotational direction, the foil air bearing comprising: The upper top foil is positioned to face the surface of the rotor; The middle top foil is positioned below the upper top foil; The lower top foil is positioned below the middle top foil; A corrugated foil is provided as an elastically deformable member and is disposed below the lower top foil; as well as Multiple slots are provided as holes extending from the upper surface of the middle top foil to the lower surface and along a longitudinal direction forming a predetermined angle with the rotation direction of the rotor. The lower top foil does not have a hole extending from the upper surface to the lower surface at the same position corresponding to the slot of the middle top foil, and the upper top foil does not have a hole extending from the upper surface to the lower surface at the same position corresponding to the slot of the middle top foil. The upper top foil is deformed into a downward concave shape at the location corresponding to the slot due to the air pressure generated by the rotation of the rotor, thereby forming a herringbone pattern. The foil air bearing includes the journal foil air bearing in which the rotor is configured as a rotating shaft, and As the rotor rotates, at locations where the distance between the rotor and the upper top foil is relatively small compared to other locations, the spacing between the slots is set to be denser than at other locations. The journal foil air bearing comprises: A base foil is arranged to surround the wave foil; as well as A connector is used to connect one end of the upper top foil, one end of the middle top foil, one end of the lower top foil, one end of the corrugated foil, and two ends of the base foil to each other, wherein the other end of the upper top foil, the other end of the middle top foil, the other end of the lower top foil, and the other end of the corrugated foil are free ends that can move freely.

2. The foil air bearing according to claim 1, wherein the plurality of slots are spaced apart from each other by a predetermined distance and are arranged symmetrically with respect to a virtual symmetry line parallel to the direction of rotation.

3. The foil air bearing of claim 1, wherein the top foil and the wave foil have shapes that can be mass-produced by automatically cutting and bending by stamping without etching or welding.

4. The foil air bearing according to claim 1, wherein the lower surface of the central top foil and the upper surface of the lower top foil are stacked on top of each other in a separable state.

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