JP2013047555A - Foil bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the pressure of fluid generated in a bearing clearance to thereby increase a load capacity by a foil bearing.SOLUTION: A free end 31 of a leaf foil (leaf 30) is alternately provided with a plurality of notches 31a and a plurality of lands 31b consecutive to bearing surfaces 33. The fluid is made to flow through the notches 31a, so that the fluid in a large clearance part T2 of a thrust bearing clearance T is made to flow dynamically, thereby increasing the fluid sent to a small clearance part T1 and increasing the pressure of the fluid.

Description

  The present invention relates to a foil bearing that supports a rotating member with a bearing surface formed on a thin-film leaf foil and a fluid film pressure generated in a wedge-shaped bearing gap formed on the bearing surface.

  The shafts of gas turbines and superchargers (such as turbochargers) are driven to rotate at high speed. Further, the turbine blade attached to the shaft is exposed to high temperature. For this reason, bearings that support these shafts are required to withstand harsh environments such as high temperature and high speed rotation. An oil-lubricated rolling bearing or an oil dynamic pressure bearing may be used as a bearing for this type of application. However, when lubrication with a liquid such as lubricating oil is difficult, when it is difficult to separately provide an auxiliary machine for the lubricating oil circulation system from the viewpoint of energy efficiency, or when resistance due to liquid shear becomes a problem, etc. Below, the use of bearings with oil is restricted. Therefore, an air dynamic pressure bearing has attracted attention as a bearing suitable for use under the above conditions.

  As an air dynamic pressure bearing, one in which both the rotating side and the fixed side bearing surfaces are made of a rigid body is generally used. However, in this type of air dynamic pressure bearing, if the bearing clearance formed between the rotating and stationary bearing surfaces is insufficiently controlled, a self-excited shaft called a whirl when the stability limit is exceeded. It is easy to produce the touch around. Therefore, gap management according to the rotation speed used is important. However, since the width of the bearing gap fluctuates under the influence of thermal expansion in an environment where the temperature changes rapidly, such as a gas turbine or a supercharger, accurate gap management becomes extremely difficult.

  Foil bearings are known as bearings that can easily manage clearances even in environments with large temperature changes. In the foil bearing, a bearing surface is constituted by a thin film (foil) having low rigidity with respect to bending, and the load is supported by allowing the bearing surface to bend. In the foil bearing, an appropriate bearing gap is formed according to operating conditions such as the rotational speed and load of the shaft and the ambient temperature due to the flexibility of the foil. For this reason, a foil bearing has the characteristic that it is excellent in stability, and it can be used at high speed compared with a general air dynamic pressure bearing. In addition, in general dynamic pressure bearings, it is necessary to always maintain a bearing gap of about several μm. Therefore, it is difficult to strictly manage the gap considering tolerances during manufacturing and thermal expansion when temperature changes are severe. It is. On the other hand, in the case of a foil bearing, it is sufficient to manage the bearing gap of about several tens of μm, and there is an advantage that its manufacture and gap management are easy.

  Further, since the reaction force in the thrust direction of the air flow generated by the high-speed rotation of the turbine is applied to the shaft of the gas turbine or the supercharger, it is necessary to support the shaft not only in the radial direction but also in the thrust direction. For example, Patent Documents 1 to 3 show a foil bearing that supports a rotating shaft in a radial direction. Patent Documents 4 to 6 show foil bearings that support the rotating shaft in the thrust direction.

JP 2002-364463 A JP 2003-262222 A JP 2009-299748 A JP 61-36725 A Japanese Utility Model Publication No. 61-38321 Japanese Unexamined Patent Publication No. 63-195212

  For example, a foil bearing 100 shown in FIG. 20 is used for supporting in the thrust direction, and is a so-called leaf type foil bearing having a plurality (eight in the illustrated example) of leaf foils 110. Each leaf foil 110 is fixed to the end surface of the disc-shaped thrust member 120 with one end in the circumferential direction as a free end 111 and the other end in the circumferential direction as a fixed end 112. Each leaf foil 110 is formed with a thrust bearing surface 113. As shown in FIG. 21, a wedge-shaped thrust bearing gap 140 is formed between the end surface 131 of the rotating member 130 and the thrust bearing surface 113 of the leaf foil 110. A small gap portion 141 of the thrust bearing gap 140 is formed in the vicinity of the free end 111 of the leaf foil 110, and a large gap portion 142 of the thrust bearing gap 140 is formed immediately after exceeding the free end 111 (near the fixed end 112 in the illustrated example). Is done. When the rotating member 130 rotates in the direction of arrow C, the fluid film in the thrust bearing gap 140 flows. At this time, the fluid flowing through the small gap portion 141 has a high pressure, and the fluid flowing through the large gap portion 142 has a relatively low pressure. Therefore, as shown in FIG. 22, a high pressure region H is formed near the free end 111 of the leaf foil 110, and a low pressure region L is formed near the fixed end 112 of the leaf foil 110. Note that the spring 150 in FIG. 21 schematically represents the spring property of the leaf foil 110.

At this time, the flow velocity of the fluid flowing through the large gap 142 is not uniform. That is, in the vicinity of the end face of the rotating member 130 (the upper portion in the illustrated example) in the large gap 142, the flow rate increases due to the flow of high-pressure fluid from the small gap 141 (the high pressure region H) (see FIG. 21). Arrow v ₁ '). On the other hand, the fluid in the vicinity of the thrust bearing surface 113 (the lower portion in the illustrated example) in the large gap 142 is not easily affected by the high-pressure fluid flowing from the small gap 141, so the flow velocity is slow (arrow in FIG. 21). v ₂ '). For this reason, the fluid in the lower part of the large gap 142 in the figure hardly flows into the small gap 141, and the pressure of the fluid in the small gap 141 is difficult to increase.

  The above problems are problems that occur in leaf-type foil bearings, and similarly occur not only in foil bearings that are used for support in the thrust direction but also in foil bearings that are used for support in the radial direction.

  Accordingly, an object of the present invention is to increase the pressure of fluid generated in the bearing gap and increase the load capacity of the leaf type foil bearing.

  The present invention made to achieve the above object comprises a fixing member, a rotating member, and a plurality of leaf foils arranged between the fixing member and the rotating member and having one circumferential end as a free end, A foil bearing that forms a wedge-shaped bearing gap on the bearing surface provided on the leaf foil and supports the rotating member with a fluid film generated in the bearing gap, and a plurality of notches at the free end of the leaf foil, A plurality of continuous land portions are alternately provided on the bearing surface.

Thus, by providing a plurality of notches and lands alternately at the free end of the leaf foil, the fluid in the bearing gap can be made to flow dynamically, and the pressure of the fluid in the bearing gap can be increased. The reason is as follows. For example, as shown in FIG. 6, when the free end 31 of the leaf foil 30 is formed in a zigzag shape and a plurality of cutout portions 31a and land portions 31b are alternately provided, as shown in FIG. When the small gap portion T1 of the thrust bearing gap T is formed in the shaft and the rotating member (flange portion 40) rotates in the direction of arrow D, the fluid pressure in the small gap portion T1 is increased. A part of this high-pressure fluid escapes to the back side (the opposite side to the bearing surface 33) of the leaf foil 30 through the notch 31a (see arrow A in FIG. 4), so that a large gap portion of the thrust bearing gap T is obtained. fluid T2 thrust member 21 side portion (in the figure the lower part) to flow (see the arrow v ₂ in FIG. 4). As a result, the momentum of the fluid in the large gap portion T2 of the thrust bearing gap T increases, and the amount of fluid flowing from the large gap portion T2 into the small gap portion T1 is increased compared to the case shown in FIG. The pressure in the part T1 is increased.

  The free end of the leaf foil can be formed, for example, in a zigzag shape (see FIGS. 5 and 6) or in a waveform (see FIG. 7).

  In the foil bearing described above, for example, a plurality of leaf foils and a connecting portion that connects the plurality of leaf foils can be integrally provided on one foil. Thereby, several leaf foil can be attached to a fixed member or a rotation member at once. Moreover, if a foil member is constituted by combining a plurality of such foils, more leaf foils can be attached to the fixed member or the rotating member at a time.

  In the foil bearing as described above, a fluid film is formed between the bearing surface of the leaf foil and the surface facing it during high-speed operation, and these surfaces are in a non-contact state. In the rotating state, it becomes difficult to form a fluid film having a surface roughness higher than the surface roughness of the bearing surface of the leaf foil and the surface facing the bearing surface. Therefore, there is a possibility that the rotating member and the fixed member are in contact with each other with the leaf foil interposed therebetween, and the surface of the leaf foil is damaged. For this reason, it is preferable to provide a coating on the bearing surface of the leaf foil to prevent damage.

  In addition, a slight displacement slide occurs between a plurality of leaf foils or between the leaf foil and a surface to which the leaf foil is fixed, due to load fluctuation or vibration. For this reason, it is preferable to provide a film on the surface opposite to the bearing surface of the leaf foil to prevent damage due to sliding.

  Since the foil bearing is often used in a place where it is difficult to lubricate with a liquid, a DLC film, a titanium aluminum nitride film, or a molybdenum disulfide film can be used for the coating as described above. DLC films and titanium aluminum nitride films are hard, have a low coefficient of friction, and are excellent in strength. On the other hand, since the molybdenum disulfide film can be sprayed by spraying or the like, a film can be easily formed.

  The configuration as described above can be applied not only to the foil bearing used for supporting in the thrust direction but also to the foil bearing used for supporting in the radial direction.

  The foil bearing as described above can be suitably used for supporting a rotor of a gas turbine or a supercharger.

  As described above, according to the present invention, by increasing the momentum of the fluid in the bearing gap, the pressure of the fluid film generated in the bearing gap can be increased, and the load capacity of the foil bearing can be increased.

It is a figure which shows a micro gas turbine notionally. It is sectional drawing which shows the support structure of the rotor of the said micro gas turbine. It is sectional drawing of the radial foil bearing integrated in the said rotor support structure. It is a thrust foil bearing integrated in the said rotor support structure, Comprising: It is a side view of the thrust foil bearing which concerns on embodiment of this invention. It is a perspective view of the bearing member of the said thrust foil bearing. It is a top view of the leaf foil of the said thrust foil bearing. It is a top view of the leaf foil of the thrust foil bearing which concerns on other embodiment. It is a top view of the leaf foil of the thrust foil bearing which concerns on other embodiment. It is a top view of the bearing member of the thrust foil bearing which concerns on other embodiment. It is a top view of the bearing member of the thrust foil bearing which concerns on other embodiment. It is a perspective view of the bearing member of the thrust foil bearing which concerns on other embodiment. It is a top view of the foil of the thrust foil bearing of FIG. (A)-(c) is a perspective view which shows a mode that two foils of the thrust foil bearing of FIG. 11 are assembled | attached. It is a top view of the foil of the radial foil bearing which concerns on embodiment of this invention. It is sectional drawing of the said radial foil bearing. It is sectional drawing of the radial foil bearing which concerns on other embodiment. It is a perspective view of the foil member of the said radial foil bearing. (A) is a top view explaining the assembly method of the said foil member, (b) is the same side view. It is a figure which shows a supercharger notionally. It is a perspective view of the conventional foil bearing. It is a side view of the foil bearing of FIG. It is a top view of the leaf foil of the foil bearing of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a configuration of a gas turbine device called a micro gas turbine. The micro gas turbine mainly includes a turbine 1 and a compressor 2 that form blade rows, a generator 3, a combustor 4, and a regenerator 5. The turbine 1, the compressor 2, and the generator 3 are provided with a common shaft 6 that extends in the horizontal direction, and the shaft 6, the turbine 1, and the compressor 2 constitute a rotor that can rotate integrally. Air sucked from the intake port 7 is compressed by the compressor 2, heated by the regenerator 5, and then sent to the combustor 4. The compressed air is mixed with fuel and burned, and the turbine 1 is rotated by the high-temperature and high-pressure gas at this time. The rotational force of the turbine 1 is transmitted to the generator 3 via the shaft 6, and the generator 3 rotates to generate electric power, and this electric power is output via the inverter 8. Since the gas after rotating the turbine 1 is at a relatively high temperature, the heat of the gas after combustion is regenerated by sending this gas to the regenerator 5 and exchanging heat with the compressed air before combustion. Use. After the heat exchange in the regenerator 5 passes through the exhaust heat recovery device 9, it is discharged as exhaust gas.

  FIG. 2 shows a support structure of the rotor, in particular, a support structure of the shaft 6 in the axial direction between the turbine 1 and the compressor 2. Since this region is adjacent to the turbine 1 rotated by high-temperature and high-pressure gas, an air dynamic pressure bearing, particularly a foil bearing is preferably used here. Specifically, the rotor is rotatably supported by a radial foil bearing 10 that supports the shaft 6 in the radial direction and a thrust foil bearing 20 that supports the flange portion 40 provided on the shaft 6 in both thrust directions. . In the present embodiment, a case where the foil bearing according to one embodiment of the present invention is applied to the thrust foil bearing 20 will be described.

  As shown in FIG. 3, the radial foil bearing 10 includes a cylindrical outer member 11 in which a shaft 6 is inserted on the inner periphery and fixed to a casing 42 (see FIG. 2), and an inner peripheral surface of the outer member 11. It consists of a plurality of leaf foils (leafs 12) fixed to 11a and arranged side by side in the circumferential direction.

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

  Each leaf 12 is formed of a metal foil, one end 12a in the circumferential direction (the rotation side of the shaft 6 (see the arrow) leading side) is a free end, and the other end 12b in the circumferential direction is an outer end. It is fixed to the direction member 11. The fixed end 12 b of the leaf 12 is fitted and fixed to an axial groove 11 b formed on the inner peripheral surface 11 a of the outer member 11. A partial region on the free end 12 a side of the leaf 12 is arranged so as to overlap with the other leaf 12 in the radial direction. The surfaces on the inner diameter side of the plurality of leaves 12 constitute a radial bearing surface 12 c having a smooth curved surface without holes or steps, and between the radial bearing surface 12 c of each leaf 12 and the outer peripheral surface 6 a of the shaft 6. A wedge-shaped radial bearing gap R having a narrow radial width toward one circumferential direction is formed.

  As shown in FIG. 4, the thrust foil bearing 20 has a disc-like shape fixed to a flange portion 40 (rotating member, see FIG. 2) provided to protrude from the outer peripheral surface 6 a of the shaft 6 to the outer diameter, and a casing 42. A thrust member 21 (fixing member, see FIG. 5) and a plurality of leaf foils (leafs 30) disposed between the flange portion 40 and the thrust member 21 are provided. In the present embodiment, bearing members 20a are provided on both axial sides of the flange portion 40 (see FIG. 2), and the bearing member 20a includes a disc-shaped thrust member 21 (fixing member) and a thrust as shown in FIG. It is comprised with the some leaf 30 fixed to the end surface 21a of the member 21 in the state arranged in the circumferential direction at equal intervals.

  The leaf 30 is made of a single metal foil having the same material and thickness as the leaf 12 described above, and forms a fan shape along the circumferential direction of the thrust member 21. One end of the leaf 30 in the circumferential direction (the leading side in the rotational direction of the shaft 6, the left side in the figure) is a free end 31, and the other end in the circumferential direction is a fixed end 32 fixed to the thrust member 21. The Of each leaf 30, a curved thrust bearing surface 33 is provided on the surface opposite to the thrust member 21. The curved thrust bearing surface 33 projects from the flange portion 40 side. The thrust bearing surface 33 has a smooth curved surface with no holes or steps. The spring 30a schematically represents the spring property of the leaf 30 and is not actually provided.

  As shown in FIG. 6, a plurality of notch portions 31 a and a land portion 31 b continuous with the thrust bearing surface 33 are provided at the free end 31 of each leaf 30, in the extending direction of the free end 31 (in this embodiment, In the radial direction). In the illustrated example, by forming the free ends 31 in a zigzag shape, triangular cut portions 31a and land portions 31b are alternately formed.

  When the shaft 6 rotates in one circumferential direction, between the radial bearing surface 12c of each leaf 12 of the radial foil bearing 10 and the outer peripheral surface 6a of the shaft 6, a wedge shape with a radial width narrowing toward the circumferential direction one side. The radial bearing gap R is formed (see FIG. 3). The fluid film (air film) generated in the radial bearing gap R supports the shaft 6 in a non-contact manner in the radial direction. At the same time, between the thrust bearing surface 33 of each leaf 30 of the thrust foil bearing 10 and the end surfaces 41 on both axial sides of the flange portion 40, the thrust bearing gap T narrowed in the axial direction toward one circumferential direction. Is formed (see FIG. 4). The shaft 6 is supported in a non-contact manner in both thrust directions by a fluid film (air film) generated in the thrust bearing gap T. Note that the actual radial bearing gap R and thrust bearing gap T are as small as several tens of μm, but the widths are exaggerated in FIGS.

At this time, as shown in FIG. 4, a part of the high-pressure fluid in the small gap portion T1 of the thrust bearing gap T passes to the leading side in the rotational direction of the shaft 6 as a result, thereby the vicinity of the flange portion 40 of the large gap portion T2. The fluid in (the upper part in the figure) flows (see arrow v _{1 in} FIG. 4). At the same time, a part of the fluid in the small gap portion T1 escapes to the back side (lower side in the figure) of the leaf 30 through the notch portion 31a, thereby the vicinity of the thrust bearing surface 33 (lower part in the figure) of the large gap portion T2. ) fluid flow (see arrows v ₂ in FIG. 4). As a result, the fluid in the entire large gap portion T2 dynamically flows and the amount of fluid flowing from the large gap portion T2 into the next small gap portion T1 increases, so the pressure generated in the small gap portion T1 is increased to increase the thrust direction. The load capacity can be increased.

  At this time, due to the flexibility of the leaf 12 of the radial foil bearing 10 and the leaf 30 of the thrust foil bearing 20, the bearing surfaces 12 c and 33 of each leaf 12, 30 cause the load, the rotational speed of the shaft 6, and the ambient temperature. Therefore, the radial bearing gap R and the thrust bearing gap T are automatically adjusted to appropriate widths according to the operating conditions. Therefore, the radial bearing gap R and the thrust bearing gap T can be managed to the optimum width even under severe conditions such as high temperature and high speed rotation, and the shaft 6 can be stably supported.

  In the foil bearings 10 and 20, the radial bearing surface 12 c of the leaf 12 and the thrust bearing surface 33 of the leaf 30, the outer peripheral surface 6 a of the shaft 6, and the end surface of the flange portion 40 are rotated at a low speed immediately before the shaft 6 is stopped or immediately after starting. It becomes difficult to form an air film having a thickness greater than the surface roughness on 41. Therefore, metal contact is generated between the radial bearing surface 12 c and the outer peripheral surface 6 a of the shaft 6 and between the thrust bearing surface 33 and the flange portion 40. In order to reduce the frictional force due to the metal contact and to damage the leaves 12 and 30 and reduce the torque, it is desirable to form a coating that reduces the friction on the radial bearing surface 12c and the thrust bearing surface 33. As this type of coating, for example, a DLC film, a titanium aluminum nitride film, or a molybdenum disulfide film can be used. The DLC film, titanium or aluminum nitride film can be formed by CVD or PVD, and the molybdenum disulfide film can be easily formed by spraying. In particular, since the DLC film and the titanium aluminum nitride film are hard, by forming a film with them, the wear resistance of the radial bearing surface 12c and the thrust bearing surface 33 can be improved, and the bearing life is increased. be able to. The coating as described above is formed on the outer peripheral surface 6a of the shaft 6 and the end surface 41 of the flange portion 40 opposed to these surfaces instead of or in addition to the radial bearing surface 12c and the thrust bearing surface 33. It may be formed.

  During the operation of the bearing, the back surface of the leaf 12 (surface opposite to the radial bearing surface 12c) and the inner peripheral surface 11a of the outer member 11, or the back surface of the leaf 30 (surface opposite to the thrust bearing surface 33). ) And the end surface 21 a of the thrust member 21, so that the sliding portion, that is, the rear surfaces of the leaves 12 and 30, the inner peripheral surface 11 a of the outer member 11 in contact with this, and the thrust member 21 Wear resistance may be improved by forming the above-mentioned film on one or both of the end faces 21a. In order to improve the vibration damping action, it may be more convenient that a certain amount of frictional force exists in the sliding portion. Therefore, the low friction property is not required for the coating of this portion. Therefore, it is preferable to use a DLC film, titanium, or an aluminum nitride film as the coating of this portion.

  The present invention is not limited to the above embodiment. In the following description, portions having the same functions as those of the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.

  The shape of the free end 31 of the leaf 30 is not limited to the above. For example, as shown in FIG. 7, the free end 31 of the leaf 30 may be formed in a corrugated shape. Alternatively, as shown in FIG. 8, the free end 31 of the leaf 30 may be provided with a plurality of cuts 31 a at a plurality of locations separated in the radial direction. Further, the shape of the cut 31a and the land portion 31b may be a rectangle (see FIG. 6), a waveform (see FIG. 7), an arc shape (see FIG. 8), a rectangle or a trapezoid (not shown).

  In the above embodiment, the case where the free end 31 of the leaf 30 extends along the radial direction has been shown. However, the present invention is not limited to this, and for example, as shown in FIGS. The outer diameter end of the free end 31 may be inclined toward the rotation direction leading side of the shaft 6 toward the inner diameter side. Thereby, as the shaft 6 rotates, the air on the outer diameter side of the bearing member 20a of the thrust foil bearing 20 is sent along the leaf 30 to the inner diameter side (see the dotted arrow in FIG. 9), so that the thrust bearing gap T A large amount of air can be fed to the thrust bearing gap T, and the pressure in the thrust bearing gap T is further increased. Specifically, for example, as shown in FIG. 9, the free ends 31 of the leaves 30 can be arranged in a pump-in type spiral shape. Alternatively, as shown in FIG. 10, the free end 31 of the leaf 30 may have a herringbone shape. Here, the herringbone shape means a substantially V shape in which the outer diameter end and the inner diameter end of the free end 31 are inclined toward the rotation direction leading side of the shaft 6 toward the radial center.

  In the above-described embodiment, a case where a plurality of leaf foils are formed separately one by one has been described. However, the present invention is not limited to this. For example, a plurality of leaf foils may be formed in one foil. For example, in the embodiment shown in FIG. 11, the foil member 50 is configured by combining two foils 60 and 60 ′ having a plurality of leaf foils, and the foil member 50 is fixed to the thrust member 21.

  Here, the configuration of the foils 60 and 60 'will be described. Since the foils 60 and 60 'have exactly the same configuration, only the configuration of one foil 60 will be described, and the description of the other foil 60' will be omitted (in FIGS. 11 and 13, the other foil 60 'is omitted). Of these, a portion corresponding to one of the foils 60 is indicated with “′”).

  The foil 60 has a circular shape, and a circular hole 63 through which the shaft 6 is inserted is provided at the center thereof. In the present embodiment, a plurality of (four in the illustrated example) leaves 61 arranged at equal intervals in the circumferential direction by making a substantially L-shaped cut into one foil 60 by wire cutting or pressing. And the connection part 62 is formed. Specifically, the circular foil 60 extends in a zigzag shape from the hole 63 toward the outer diameter at a plurality of equally spaced circumferential positions (four in the illustrated example), and ends in front of the outer diameter end of the foil 60. A radial cut 64 is provided. A circumferential cut 65 extends from the outer diameter end of each cut 64 to the other circumferential direction (the rear side in the rotational direction of the shaft 6, the counterclockwise direction in FIG. 12). By forming these incisions 64 and 65 in the foil 60, a plurality of leaves 61 having one end 61a in the circumferential direction as a free end that can freely move up and down in the axial direction, and a connecting portion 62 that connects them are provided. It can be formed integrally. The connecting portion 62 includes an annular portion 62a surrounding the outer periphery of the plurality of leaves 61, and a plurality (four in the illustrated example) of extending portions 62b extending from the annular portion 62a toward the inner diameter. The leaf 61 is continuous with the other circumferential end 61b (shown by a dotted line in FIG. 12). In the example of illustration, the extension part 62b of the connection part 62 and the leaf 61 are the same lengths in the circumferential direction, and these are provided alternately in the circumferential direction. The free end 61a of the leaf 61 is formed in a zigzag shape having a plurality of cutout portions 61a1 and land portions 61a2.

  The two foils 60, 60 'are assembled by the method shown in FIG. The two foils 60 and 60 'are completely the same in material and shape, but in FIG. 13, one foil 60' is dotted to facilitate understanding. Here, the description will be made assuming that the central axis direction of the foils 60, 60 'is the vertical direction.

  First, the two foils 60, 60 'shown in FIG. 13A are arranged one above the other as shown in FIG. 13B, and the lower side of the foil 60 is lowered from the radial cut 64 of the upper foil 60. Insert the free end 61a 'of the leaf 61' of the foil 60 '. As a result, the free end 61a 'of the leaf 61' of the lower foil 60 'is disposed above the connecting portion 62 (extending portion 62b) of the upper foil 60. Then, by rotating the two foils 60, 60 ′ relatively, as shown in FIG. 13C, the free end 61a ′ of the leaf 61 ′ of the lower foil 60 ′ is moved to the upper foil 60. It reaches above the end 61b of the leaf 61. Thus, the foil member 50 in which the leaves 61 of the upper foil 60 and the leaves 61 'of the lower foil 60' are alternately arranged in the circumferential direction is obtained. At this time, the thrust bearing surfaces 61c and 61c 'provided on the upper surfaces of the leaves 61 and 61' are alternately arranged in the circumferential direction and are arranged without interruption in the circumferential direction. By fixing the foil member 50 to the thrust member 21, the bearing member 20a shown in FIG. 11 is completed.

  In the above embodiment, the present invention is applied to the thrust foil bearing that supports the rotor in the thrust direction. However, the present invention is not limited to this, and the present invention is applied to the radial foil bearing that supports the rotor in the radial direction. You can also For example, as shown in FIG. 14, at the free end 12a of the leaf 12 attached to the outer member 11 (fixing member), a plurality of notches 12a1 and a plurality of land portions 12b continuous to the radial bearing surface 12c Can be provided alternately. Thereby, as shown in FIG. 15, among the radial bearing clearance R between the radial bearing surface 12c and the outer peripheral surface 6a of the shaft 6, the small clearance R1 formed in the vicinity of the free end 12a of the radial bearing surface 12c. The fluid flows to the outer diameter side through the notch 12a1 (see arrow B). Accordingly, the fluid in the large gap portion R2 can be dynamically flowed, and the amount of fluid flowing into the small gap portion R1 from the large gap portion R2 can be increased to increase the pressure in the small gap portion R1.

  Moreover, in said radial foil bearing 10, a some leaf can also be comprised with one foil. For example, the foil member 70 shown in FIGS. 16 and 17 has a spiral shape in which foils are overlapped in the radial direction by rotating one strip-like foil around the axis 6. In this embodiment, the case where the number of turns is two and the both ends 70b and 70c of the foil are arranged at substantially the same position in the circumferential direction is illustrated. Thereby, the double foil part W which overlapped two foils on the radial direction over substantially the perimeter of the foil member 70 is formed. Of the double foil portion W, the outer foil is partially raised to the inner diameter side to form the first leaf 71 having the inner diameter end as a free end, and the inner foil is partially raised to the inner diameter side. Thus, the second leaf 72 having the inner diameter end as a free end is formed. The first leaf 71 and the second leaf 72 are alternately arranged in the circumferential direction except for the vicinity of both end portions 70b and 70c of the foil.

  The inner peripheral surfaces of the first leaf 71 and the second leaf 72 constitute a curved bearing surface 70 d that is convex on the outer diameter side, and between the bearing surface 70 d and the outer peripheral surface 6 a of the shaft 6, A wedge-shaped radial bearing gap R that decreases in the rotational direction is formed. The free ends of the leaves 71 and 72 overlap in a radial direction with other leaves adjacent to the leading side in the rotational direction.

  When manufacturing the foil member 70 shown in FIG. 18, first, as shown in FIG. 18 (a), one side edge portion of the flat metal foil 70 made of metal is cut at an appropriate interval by wire cutting or pressing. A plurality of L-shaped cuts 73 are formed. At this time, the region 77 between the other side edge portion 76 and the adjacent notch 73 is left in an integral state without being divided. Next, as shown in FIG. 4B, the tongue piece portions 74 formed by the cuts 73 are bent in the same direction, and then the flat foil 70 is double-vortexed with each tongue piece portion 74 as the inner diameter side. Roll to shape. When rolling the foil of the second roll, the tongue piece 74 of the second roll is disposed between the tongue pieces 74 adjacent to the first roll. At this time, the second tongue piece 74 is introduced between the first tongue piece 74 through the opening 75 formed in the first foil 70 by cutting and raising the tongue piece 74. By the above procedure, the first leaf 71 and the second leaf 72 are formed at each tongue piece 74. These leaves 71 and 72 are held by an annular portion 70e integrally having a side edge portion 76 and a region 77 between adjacent notches so as to be elastically deformable.

  The foil member 70 manufactured by the above procedure is fixed to the outer member 11 by attaching one end of the foil member 70 to the outer member 11 in a state of being arranged on the inner diameter side of the outer member 11. For example, in the manufacturing process of the foil member 70 described above, an attachment portion 70a standing in the outer diameter direction is formed at one end portion of the belt-like foil, and this attachment portion 70a is formed in the axial groove 11b formed on the inner periphery of the outer member 11. By fitting and fixing, the foil member 70 can be fixed to the outer member 11.

  In the above embodiment, the case where the leaf foil is attached to the fixing member (the thrust member 21, the outer member 11) has been described, but the leaf foil may be attached to the rotating member (the shaft 6, the flange portion 40). In this case, a wedge-shaped thrust bearing gap is formed between the bearing surface provided on the leaf foil and the fixing member. However, in this case, since the leaf foil rotates at a high speed together with the shaft 6, the leaf foil may be deformed by centrifugal force. In particular, when the leaf foil of the thrust foil bearing 20 is rotated, there is a high possibility that the leaf foil is deformed by centrifugal force. Therefore, from the viewpoint of avoiding the deformation of the leaf foil, it is preferable to attach the leaf foil to the fixing member.

  In the above embodiment, the thrust foil bearing 20 has the bearing member 20a on both axial sides of the flange portion 40 and supports the flange portion 40 in both thrust directions. It is good also as a structure which provides the bearing member 20a only in the axial direction one side of the flange part 40, and supports only to a thrust direction one side. Such a configuration can be applied to the case where the other support in the thrust direction is unnecessary or the case where the other support in the thrust direction is achieved by another configuration.

  Moreover, although the case where the foil bearing which concerns on this invention was applied to the gas turbine was shown in the above embodiment, you may apply not only to this but to a supercharger as shown, for example in FIG. This supercharger is a so-called turbocharger that sends air to the engine 83 and includes a compressor 81 and a turbine 82. The compressor 81 and the turbine 82 are connected by a shaft 6. The shaft 6 is supported by the radial foil bearing 10 and the thrust foil bearing 20 in the radial direction and in both thrust directions. In the illustrated example, the radial foil bearings 10 are provided at two locations separated in the axial direction. Air sucked from an intake port (not shown) is compressed by the compressor 81, mixed with fuel, and supplied to the engine 83. The engine 83 burns compressed air mixed with fuel, and the turbine 82 is rotated by the high-temperature and high-pressure gas exhausted from the engine 83. The rotational force of the turbine 82 at this time is transmitted to the compressor 81 via the shaft 6. The gas after rotating the turbine 82 is discharged to the outside as exhaust gas.

  The foil bearing according to the present invention is not limited to a micro turbine or a supercharger, and it is difficult to lubricate with a liquid such as a lubricating oil. From the viewpoint of energy efficiency, it is difficult to separately provide an auxiliary machine for a lubricating oil circulation system. In addition, it can be widely used as a bearing for a vehicle such as an automobile used under a restriction that resistance due to liquid shear becomes a problem, and further as a bearing for industrial equipment.

  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.

DESCRIPTION OF SYMBOLS 1 Turbine 2 Compressor 3 Generator 6 Shaft 10 Radial foil bearing 11 Outer member 12 Leaf 12c Radial bearing surface 20 Thrust foil bearing 21 Thrust member (fixing member)
30 Leaf (leaf foil)
31 Free end 31a Notch portion 31b Land portion 32 Fixed end 33 Thrust bearing surface 40 Flange portion (rotating member)
H High pressure region L Low pressure region R Radial bearing clearance T Thrust bearing clearance T1 Small clearance T2 Large clearance

Claims (12)

A fixed member, a rotating member, and a plurality of leaf foils arranged between the fixing member and the rotating member and having one end in the circumferential direction as a free end, and a wedge-shaped bearing gap formed on a bearing surface provided on the leaf foil A foil bearing that supports the rotating member with a fluid film formed in the bearing gap,
A foil bearing characterized in that a plurality of cutout portions and a plurality of land portions continuous with the bearing surface are alternately provided at a free end of a leaf foil.   2. The foil bearing according to claim 1, wherein the free end of the leaf foil is formed in a zigzag shape.   The foil bearing according to claim 1, wherein the free end of the leaf foil is formed in a corrugated shape.   The foil bearing in any one of Claims 1-3 which integrally provided the several leaf foil and the connection part which connects several leaf foil to one foil.   The foil bearing according to claim 4, wherein a foil member is formed by combining a plurality of the foils.   The foil bearing in any one of Claims 1-5 which provided the film in the bearing surface of the leaf foil.   The foil bearing in any one of Claims 1-6 which provided the film in the surface on the opposite side to the bearing surface of a leaf foil.   The foil bearing according to claim 6 or 7, wherein the coating is any one of a DLC film, a titanium aluminum nitride film, and a molybdenum disulfide film.   The foil bearing in any one of Claims 1-8 which support a rotation member in a thrust direction.   The foil bearing in any one of Claims 1-8 which support a rotating member in a radial direction.   The foil bearing in any one of Claims 1-10 used for the rotor support of a gas turbine.   The foil bearing in any one of Claims 1-10 used for the rotor support of a supercharger.

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