JP2012092969A - Foil bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of a foil bearing by providing a single foil member with a bearing surface and a spring that supports elastically the bearing surface.SOLUTION: The foil bearing includes a cylindrical outer member 11, a shaft 6 inserted into the inner periphery of the outer member 11, and a foil member 13 interposed between an inner peripheral surface 11b of the outer member 11 and an outer peripheral surface 6a of the shaft 6. A single foil member 13 which is cylindrical and has an end has a bearing surface 15 and a spring 16 for elastically supporting the bearing surface 15. One end of the foil member 13 is fixed to the outer member 11, and the spring 16 is protruded toward the contour side of the bearing surface 15 to slidably contact with the inner peripheral surface 11b of the outer member 11.

Description

  The present invention relates to a foil bearing in which a thin film foil member is interposed between an inner peripheral surface of an outer member and an outer peripheral surface of a shaft.

  The main shaft of a gas turbine or turbocharger is driven to rotate at high speed. Moreover, the turbine blade attached to the main shaft is exposed to high temperature. Therefore, bearings that support these main shafts are required to be able to withstand severe environments such as high temperature and high speed rotation. Oil lubricated rolling bearings and hydrodynamic pressure bearings may be used as bearings for this type of application, but if lubrication with a liquid such as lubricating oil is difficult, the auxiliary equipment of the lubricating oil circulation system from the viewpoint of energy efficiency The use of these bearings is restricted under conditions such as when it is difficult to provide a separate or when resistance due to liquid shear becomes a problem. Therefore, an air dynamic pressure bearing has attracted attention as a bearing suitable for use under such 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 radial bearing clearance formed between the rotating and stationary bearing surfaces is insufficiently managed, a self-excited so-called whirl is called when the stability limit is exceeded. It is easy for the spindle to run out. Therefore, gap management according to the rotation speed used is important. In particular, in an environment where the temperature changes drastically, such as a gas turbine or a turbocharger, the width of the radial bearing gap fluctuates due to the effect of thermal expansion, so that accurate gap management becomes extremely difficult.

  A foil bearing is known as a bearing that is less likely to cause a whirl and can easily manage a gap even in an environment with a large temperature change. 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. Normally, the inner peripheral surface of the bearing is composed of a thin plate called a top foil, and a spring-like member called a back foil is arranged on the outer diameter side to elastically support the load received by the top foil with the back foil. Yes. In this case, when the shaft rotates, an air film is formed between the outer peripheral surface of the shaft and the inner peripheral surface of the top foil, and the shaft is supported in a non-contact manner.

  Foil bearings are characterized by excellent stability because of the flexibility of the foil, an appropriate radial bearing gap is formed according to the operating conditions such as shaft rotation speed, load, and ambient temperature. It can be used at a higher speed than an air dynamic pressure bearing. In addition, the radial bearing clearance of a general dynamic pressure bearing needs to be managed in the order of 1/1000 of the shaft diameter. For example, a radial bearing clearance of about several μm needs to be always secured for a shaft having a diameter of about several millimeters. . Therefore, when taking into account manufacturing tolerances, and even thermal expansion when the temperature change is severe, strict gap management is difficult. On the other hand, in the case of a foil bearing, it is sufficient to manage a radial bearing gap of about several tens of μm, and there is an advantage that its manufacture and gap management become easy.

  As the foil bearing, a top foil is elastically supported by a cut and raised provided in a back foil (Patent Document 1), and a bearing foil is elastically supported by an elastic body formed by meshing strands (Patent Document). 2) and those having a back foil provided with a support portion that contacts the inner surface of the outer ring and does not move in the circumferential direction and an elastic portion that is elastically bent by the surface pressure from the top foil (Patent Document 3), etc. are known. is there.

  As a type of foil bearing, the back foil is not provided, the top foil is divided in the circumferential direction to form a leaf foil, and the leaf foils are provided in multiple places in the circumferential direction while overlapping the parts, and the leaf foils overlap. There is also a so-called leaf type that obtains springiness at a portion. In this leaf type foil bearing, the fixed bearing ring is divided into a plurality of arc-shaped ring members in the circumferential direction, one end of the foil is welded to the joining end of each arc-shaped ring member, and a Rayleigh step is bent on the foil. One formed (Patent Document 4), one formed by a piezo bimorph (Patent Document 5), one formed by a bimetal made of two types of metals having different linear expansion coefficients (Patent Document 6), etc. It is known.

JP 2002-364463 A JP 2003-262222 A JP 2009-299748 A Japanese Examined Patent Publication No. 2-20851 JP-A-4-54309 JP 2002-295467 A

  Among the conventional foil bearings, the foil bearings disclosed in Patent Documents 1 to 3 require two types of foils, a top foil and a back foil, and increase the number of parts. In addition, the assembly process is complicated, which is a factor that hinders further cost reduction of the foil bearing. In particular, the back foil often has a complicated shape, and the manufacturing process tends to be complicated, and therefore, improvement is desired.

  In the leaf type foil bearings shown in Patent Documents 4 to 6, it is necessary to individually attach a plurality of leaves to the inner periphery of the outer member. Therefore, a complicated assembly process is required, and the cost is similarly high.

  Therefore, an object of the present invention is to reduce the cost of a foil bearing.

  In order to achieve the above object, the present invention is interposed between a cylindrical outer member, a shaft inserted in the inner periphery of the outer member, and an inner peripheral surface of the outer member and an outer peripheral surface of the shaft. In a foil bearing comprising a cylindrical foil member, provided with a bearing surface that forms a radial bearing gap on the foil member, and supporting relative rotation of the shaft and the outer member by a fluid film formed in the radial bearing gap. The foil member is provided with a bearing surface and a spring portion that elastically supports the bearing surface.

  Thus, by providing both the bearing surface and the spring portion that elastically supports the bearing surface in one foil member, a flexible bearing surface can be formed by one foil member. Therefore, the cost of the foil bearing can be reduced through the reduction in the number of parts and the number of assembly steps.

  The spring portion can be configured by forming a tongue piece on the foil member and plastically deforming the tongue piece. The tongue piece can be formed by subjecting the strip-like foil to wire cutting or pressing. In this case, the spring portion can be formed in any one of a planar shape, a curved surface shape, and a cylindrical surface shape. Furthermore, the spring portion can be formed by bending the tongue piece portion a plurality of times along the axial fold line.

  By folding the tongue piece part along the circumferential folding line, the spring part and the bearing surface can be overlapped in the radial direction. In this case, the spring portion is arranged behind the bearing surface, and the bearing surface is directly supported by the elastic force in the radial direction. Therefore, the allowable deformation amount of the bearing surface is increased, the self-adjusting ability of the radial bearing gap width is enhanced, and the vibration damping effect is enhanced.

  When the tongue piece is folded back along the circumferential folding line, if this folding line exists only on one side in the axial direction of the bearing surface, an elastic force is generated at the folding line, so a slight inclination (misalignment) occurs on the bearing surface. May occur. This inclination can be eliminated by providing the folding line of the tongue piece on both axial sides of the bearing surface.

  In addition to overlapping in the radial direction as described above, the spring portion and the bearing surface may be formed at different positions in the axial direction.

  By forming the spring parts apart at a plurality of positions in the axial direction and arranging the bearing surfaces between the adjacent spring parts in the axial direction, both axial sides of the bearing surface can be elastically supported. The bending deformation of is stabilized. In particular, if the spring portions are formed at two axial positions, a single-row foil bearing can be configured. Further, if the spring portions are formed at three positions in the axial direction, a double-row foil bearing can be formed, and the bearing rigidity against moment load can be improved.

  By providing the spring portions at a plurality of locations in the circumferential direction, the elastic supporting force acting on the bearing surface can be made uniform in the circumferential direction.

  The foil member can be formed in a cylindrical shape with ends. One end of the foil member is fixed to the outer member or the shaft. In the former case, the spring part is arranged on the outer diameter side of the bearing surface so as to be slidably contacted with the inner peripheral surface of the outer member, and in the latter case, the spring part is arranged on the inner diameter side of the bearing surface. It is desirable that the outer peripheral surface is slidably contacted. As a result, the flexibility of the bearing surface can be increased, and the vibration damping action by the foil member can be enhanced.

  A member facing the bearing surface is slidably contacted with the bearing surface of the foil member via a radial bearing gap in a low-speed rotation state immediately after starting or immediately after stopping. By forming a coating on the bearing surface, the bearing surface can be protected and wear of the bearing surface during sliding contact can be suppressed.

  As described above, when the spring portion is arranged on the outer diameter side of the bearing surface and is slidably contacted with the inner peripheral surface of the outer member, the spring portion sliding with each other and the inner peripheral surface of the outer member Of these, it is desirable to form a film on either one or both. The frictional characteristics of the sliding part influence the vibration damping property of the foil member. For this reason, by forming the coating film, it is possible to obtain an optimum frictional force at the sliding portion. When the spring part is arranged on the inner diameter side of the bearing surface and is slidably contacted with the outer peripheral surface of the shaft, for the same reason, either one of the spring part sliding with each other and the outer peripheral surface of the shaft Alternatively, it is desirable to form a film on both sides.

  As each of the above-mentioned coatings, particularly the coating on the bearing surface, it is desirable to use a coating that reduces the surface friction. As a result, it is possible to reduce the torque by reducing the friction torque immediately after starting and immediately after stopping.

  As the low friction coating, any of a DLC coating, a titanium aluminum nitride coating, and a diverted molybdenum coating can be used. Since the DLC coating and the titanium aluminum nitride coating are hard coatings, the use of these can not only reduce friction but also increase the bearing life by improving wear resistance.

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

  According to the present invention, the number of parts can be reduced, and the cost of the foil bearing can be reduced through the reduction of parts cost and assembly cost.

It is a figure which shows notionally the structure of a micro gas turbine. It is sectional drawing which shows the support structure of the rotor in the said micro gas turbine. It is a front view which shows one Embodiment of the foil bearing concerning this invention. It is a perspective view of the foil member used for the foil bearing shown in FIG. It is a top view which shows the metal raw material for forming a foil member. It is sectional drawing which shows the various forms of the tongue piece part formed in the metal raw material. It is a perspective view which shows the foil member for double row foil bearings. It is a top view which shows the manufacturing process of the foil member concerning other embodiment. It is a perspective view which shows the manufacturing process of the foil member concerning other embodiment. It is a perspective view which shows the manufacturing process of the foil member concerning other embodiment. It is sectional drawing of the foil bearing which uses the foil member concerning other embodiment. It is the top view which developed the foil member concerning other embodiments. It is a perspective view which shows the manufacturing process of the foil member concerning other embodiment. It is the top view which developed the foil member concerning other embodiments. It is a perspective view which shows the manufacturing process of the foil member concerning other embodiment. It is the top view which developed the foil member concerning other embodiments. It is a front view which shows other embodiment of a foil bearing. It is a figure which shows notionally the structure of a supercharger.

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

  FIG. 1 conceptually shows the 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. Fuel is mixed with this compressed air and burned, and the turbine 1 is rotated by high-temperature and high-pressure gas. 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. The gas that has been subjected to heat exchange in the regenerator 5 is discharged as exhaust gas after passing through the exhaust heat recovery device 9.

  FIG. 2 shows an example of a rotor support structure in the micro gas turbine. In this support structure, the radial bearings 10 are arranged at two locations in the axial direction, and the thrust bearings 20 and 20 are arranged on both axial sides of the flange portion 6b of the shaft 6, so that the shaft 6 is in the radial direction and both thrust directions. It is supported.

  In this support structure, the region between the turbine 1 and the compressor 2 is adjacent to the turbine 1 that is rotated by high-temperature, high-pressure gas, and therefore has a high-temperature atmosphere. In this high temperature atmosphere, the lubricant composed of lubricating oil, grease and the like is altered and evaporated, so it is difficult to apply a normal bearing (such as a rolling bearing) using these lubricants. Therefore, as the bearings 10 and 20 used in this type of support structure, an air dynamic pressure bearing, particularly a foil bearing is suitable.

  Hereinafter, the structure of the foil bearing 10 suitable for the radial bearing 10 for the micro gas turbine will be described with reference to FIGS. As shown in FIG. 3, the foil bearing 10 includes a cylindrical outer member 11 fixed to the inner periphery of a housing (not shown), a shaft 6 inserted into the inner periphery of the outer member 11, and an outer member. 11 and an end-cylindrical foil member 13 interposed between the inner peripheral surface of 11 and the outer peripheral surface of the shaft 6.

  As shown in FIG. 4, the bearing surface 15 and the spring portion 16 are integrally formed on one foil member 13. The bearing surface 15 is formed on the inner peripheral surface of the foil member 13 and has a smooth cylindrical surface shape without holes or steps. The spring portion 16 is a region that is elastically deformable in the radial direction and is provided by partially plastically deforming the foil member 13. In the illustrated example, the spring portion 16 is formed by a cut and raised projecting toward the outer diameter side of the bearing surface 15. 16 is configured. The spring parts 16 are provided at a plurality of positions in the circumferential direction at equal pitches, and are disposed on both axial sides of the bearing surface 15.

  The foil member 13 is formed of a belt-like foil having a thickness of about 20 μm to 200 μm made of a metal having a good 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.

  Hereinafter, the manufacturing procedure of the foil member 13 shown in FIG. 4 will be described. In addition, the terms “axial direction”, “radial direction”, and “circumferential direction” described below are the axial direction, radial direction in a state in which the manufactured foil member 13 is incorporated in the inner periphery of the outer member 11, And circumferential direction. Specifically, the direction along the short side of the strip-shaped foil 30 is the “axial direction”, the direction along the long side is the “circumferential direction”, and the thickness direction is the “radial direction”.

  As shown in FIG. 5, the metal strip foil 30 is prepared, and L-shaped cuts 31 are formed at a plurality of locations on both side edges by wire cutting or pressing. The notch 31 includes an axial notch 31a and a circumferential notch 31b connected to the end of the notch 31a. By the cuts 31, a plurality of tongue pieces 60 having a flap shape are formed on both axial sides of the belt-like foil 30. Next, each tongue piece 60 is bent at the root axial fold line (shown by a broken line) and raised in the radial direction, and cut up at each tongue piece 60 as shown in FIG. Form. Then, the foil member 13 shown in FIG. 4 is obtained by rolling the belt-like foil 30 in a cylindrical shape with each tongue piece 60 as the outer diameter side.

  The tongue piece 60 may be bent at a small angle θ as shown in FIG. 6 (a), or may be bent at a large angle θ exceeding 90 ° as shown in FIG. 6 (b). Alternatively, the tongue piece 60 may be bent into an arc shape as shown in FIG. 5C, or rounded into a circle as shown in FIG. 6 (a) and 6 (b) can form the flat spring portion 16, and the tongue portion 60 in FIG. 6 (c) can form the curved spring portion 16. If it is the tongue piece part 60 of the same figure (d), the cylindrical surface-shaped spring part 16 can be formed. Thus, the spring constant of the spring part 16 can be adjusted to the optimum value by adjusting the bending angle θ of the tongue piece part 60 or changing the bending form of the tongue piece part 60.

  The foil member 13 is fixed to the outer member 11 by attaching one end of the foil member 13 to the inner periphery of the outer member 11 in a state of being disposed on the inner diameter side of the outer member 11. For example, in the manufacturing process of the foil member 13 described above, an attachment portion 13a standing in the outer diameter direction is formed at one end of the belt-like foil 30, and the fitting groove 11a formed on the inner periphery of the outer member 11 is formed. The foil member 13 can be fixed to the outer member 11 by being fitted and fixed to the outer member 11. The fixing method of the attachment part 13a to the fitting groove 11a is arbitrary, and can also be fixed by adhesion or welding. Then, the foil bearing shown in FIG. 3 is completed by inserting the shaft 6 into the inner periphery of the foil member 13.

  The other end portion of the foil member 13 extends to a position close to the attachment portion 13a, and a circumferential gap t exists between the other end portion and the attachment portion 13a. Further, as shown in FIG. 3, the tips of the spring portions 16 are in elastic contact with the inner peripheral surface 11 b of the outer member 11. Each spring portion 16 functions as a leaf spring, whereby the bearing surface 15 is elastically supported by the outer member 11 via the spring portion 16. The distal end portion 16a of each spring portion 16 is not fixed to the inner peripheral surface 11b of the outer member 11, and can slide on the inner peripheral surface 11b.

  In the above configuration, when the shaft 6 is rotated in the direction of the arrow in FIG. 3, an air film is formed between the bearing surface 15 of the foil member 13 and the outer peripheral surface 6 a of the shaft 6. Thereby, an annular radial bearing gap C is formed around the shaft 6, and the shaft 6 is rotatably supported in the radial direction in a non-contact state with respect to the foil member 13. The actual radial bearing gap 7 has a very small width of about several tens of μm, but in FIG. 3, the width is exaggerated. On the inner diameter side of the region of the foil member 13 in which the circumferential row of the spring portions 16 is formed, air leaks from the gap generated by the bending of the tongue piece portion 60, so that pressure is generated on the inner diameter side of the region. There is nothing. Therefore, the inner peripheral surface of the foil member 13 in this region does not function as the bearing surface 15.

  Further, because the flexibility of the foil member 13 causes the bearing surface 15 to be arbitrarily deformed according to the operating conditions such as the load, the rotational speed of the shaft 6 and the ambient temperature, the radial bearing gap C is appropriately set according to the operating conditions. Automatically adjusted to the width. In addition, the bearing surface 15 is elastically supported by the spring portion 16, there is a gap t between both end portions of the foil member 13, the foil member 13 can be expanded and contracted, and the spring portion 16. The self-adjusting ability of the radial bearing gap width is enhanced for the reason that the tip end portion 6a of the outer member 11 is slidable with respect to the inner peripheral surface 1b of the outer member 11, or the combination of these, etc. A damping effect is also obtained. Therefore, the radial bearing gap can be managed to the optimum width even under severe operating conditions such as high temperature and high speed rotation, and the shaft 6 can be stably supported.

  In particular, in the foil bearing 10, the above functions can be obtained with only one foil member 13. Therefore, it is possible to reduce component costs and assembly costs, and to reduce the cost of the foil bearing.

  In the foil bearing 10, the formation of an air film having a thickness greater than the surface roughness of the bearing surface 15 and the outer peripheral surface 6 a of the shaft 6 cannot be expected during the low-speed rotation immediately before the shaft 6 is stopped or immediately after the shaft 6 is started. Therefore, a metal contact is produced between the foil member 13 and the outer peripheral surface 6a of the shaft 6 and the torque is increased. In order to reduce the torque by reducing the friction force at this time, it is desirable to form a low friction coating on the bearing surface 15. 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, the wear resistance of the bearing surface 15 can be improved and the bearing life can be increased by forming these films. Such film formation can be efficiently performed because the foil member 13 may be composed of only one sheet.

  During the operation of the bearing, a minute slide occurs between the tip 16a of the spring part 16 and the inner peripheral surface 11b of the outer member 11, so that this sliding part, that is, the tip 16a of the spring part 16 and this. Wear resistance may be improved by forming the above-mentioned film on the inner peripheral surface 11b of the outer member 11 that is in contact. 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.

  FIG. 7 shows another embodiment of the present invention. In this embodiment, the spring portions 16 are formed at three positions in the axial direction of the foil member 13, and the bearing surfaces 15 are formed between the adjacent spring portions 16 in the axial direction, thereby having the double-row bearing surfaces 15. It is the example which comprised the double row foil bearing. Thus, by making double the foil bearing 10, the bearing rigidity with respect to moment load can be improved, and the application expansion of a foil bearing can be aimed at. For example, in the micro gas turbine shown in FIG. 2, the two radial bearings 10 can be replaced with one bearing. If it is the structure of this invention, a double row bearing can be comprised with the foil member 13 of 1 sheet, and cost increase of a double row foil bearing does not increase a number of parts and an assembly man-hour with a double row. Can be prevented. Note that when the foil member 13 is manufactured, if the cut 31 is formed in the strip-shaped foil 30 shown in FIG. 5 by wire cutting, the number of steps is increased and the cost is increased. Therefore, the cut 31 is formed by pressing. Is desirable.

  In the above embodiment, the foil member 13 in which the bearing surface 15 and the spring portion 16 are formed at different positions in the axial direction is illustrated, but the bearing surface 15 and the spring portion 16 can be overlapped in the radial direction. Hereinafter, the manufacturing process of this type of foil member 13 will be described with reference to FIGS.

  As shown in FIG. 8, first, a plurality of L-shaped cuts 31 (similar to FIG. 5, an axial cut 31 a and a circumferential cut 31 b are formed on one side edge of the metal belt-like foil 30. ) And the tongue piece 60 is formed. At this time, the width dimension Wa of the strip-shaped portion 32 not having a cut is made equal to the width dimension Wb of the tongue piece 60 (Wa = Wb).

  Next, a plurality of tongue pieces 60 formed by the cuts 31 are folded back along the axial folding line to form a folded tongue piece 60 as shown in FIG. In FIG. 8, the mountain fold line in each tongue piece part 60 is shown with the broken line, and the valley fold line is shown with the dashed-two dotted line. Further, one end of the belt-like portion 32 is bent to form the attachment portion 13a.

  Next, as shown by the arrows in FIG. 9, the folded tongue piece 60 is folded at the root circumferential fold line 33, the tongue piece 60 is folded back, and as shown in FIG. The tongue piece 60 is overlapped behind the belt-like portion 32. Thereafter, the belt-like foil 30 is rolled into a cylindrical shape with each tongue piece 60 as the outer diameter side. As a result, the foil member 13 having the surface (inner peripheral surface) of the belt-like portion 32 as the bearing surface 15 and integrally including the spring portion 16 formed of the folded tongue piece 60 on the outer diameter side thereof is obtained. As shown in FIG. 11, the foil member 13 is arranged on the inner periphery of the outer member 11, the attachment portion 13 a is fitted and fixed in the fitting groove 11 a of the outer member 11, and further, on the inner periphery of the foil member 13. The foil bearing 10 is completed by inserting the shaft 6. Even in this configuration, the distal end portion 16 a of the spring portion 16 is slidably in contact with the inner peripheral surface 11 b of the outer member 11.

  In the foil bearing 10 shown in FIG. 11, the bearing surface 15 and the outer diameter side spring portion 16 completely overlap in the radial direction. In this case, since the bearing surface 15 is directly supported by the elastic force in the radial direction, the allowable deformation amount of the bearing surface is increased. Therefore, the self-adjusting ability of the radial bearing gap width can be enhanced, and the vibration damping effect can be further enhanced.

  FIG. 12 is a development view of the foil member 13 manufactured by the manufacturing procedure of FIGS. In the foil member 13, since the folded tongue piece 60 is folded back by the circumferential folding line 33, an elastic force is generated in the peripheral region S of the folding line 33. Since the folding line 33 is unevenly distributed on one side in the axial direction of the foil member 13, a slight misalignment may occur in the bearing surface 15 when the foil member 13 is incorporated in the outer member 11.

  When this misalignment becomes a problem, in the manufacturing process of the foil member 13 shown in FIG. 10, as shown in FIG. 13, the tongue pieces 60 are formed on both sides in the axial direction of the belt-like portion 32 of the belt-like foil 30. Is desirable. Thereafter, when the folded tongue piece 60 is folded back along the circumferential folding line 33 to roll the belt-like foil 30, the number of circumferential folding lines 33 on both axial sides of the foil member 13 is shown in FIG. Are the same (or the difference in number is small). Therefore, the elastic force generated in the peripheral region of the folding line 33 can be canceled on both sides in the axial direction, and misalignment of the bearing surface 15 can be prevented.

  In the embodiment of FIGS. 13 and 14, the circumferential position of each tongue piece 60 is matched on both sides in the axial direction, and the width dimension Wb of each tongue piece 60 is set to the width dimension Wa of the belt-like portion 32 (bearing surface 15). The case where it is set to 1/2 (Wb = Wa / 2) is illustrated. Similar effects can also be obtained when the circumferential position of each tongue piece 60 is shifted on both axial sides as shown in FIG. In this case, as shown in FIG. 16, the width dimension Wa of the belt-like portion 32 (bearing surface 15) and the width dimension Wb of each tongue piece 60 can be made equal.

  In the above description, the case where the shaft 6 is the rotation side member and the outer member 11 is the fixed side member is illustrated. On the contrary, the shaft 6 is the fixed side member and the outer member 11 is the rotation side member. Even in this case, the configuration of each of the above embodiments can be applied as it is. However, in this case, since the foil member 13 serves as the rotation side member, it is necessary to design the foil member 13 in consideration of the deformation of the entire foil member 13 due to the centrifugal force.

  Further, in each of the embodiments described above, the spring portion 16 of the foil member 13 is protruded to the outer diameter side and the tip end portion 16a is brought into contact with the inner peripheral surface 11b of the outer member 11, but FIG. As shown, the spring portion 16 of the foil member 13 may be protruded toward the inner diameter side of the bearing surface 15, and the tip end portion 16 a may be brought into contact with the outer peripheral surface 6 a of the shaft 6. In this case, the bearing surface 15 is formed on the outer peripheral surface of the foil member 13, and a radial bearing gap C is formed between the bearing surface 15 and the inner peripheral surface 11 b of the outer member 11. An attachment portion 13 a at one end of the foil member 13 is projected to the inner diameter side of the bearing surface 15, and is fitted and fixed in a fitting groove 6 b provided in the shaft 6, for example. In addition to this, the attachment portion 3a may be fixed to the shaft 6 by adhesion or welding. In FIG. 17, the outer member 11 is the rotating side, but the outer member 11 may be the fixed side. However, if the outer member 11 is on the fixed side, the foil member 13 is on the rotating side. Therefore, when designing the foil member 13, it is necessary to consider deformation of the foil member 13 due to centrifugal force. With the above configuration, the same effects as those of the above embodiments can be obtained.

  The application target of the foil bearing 10 according to the present invention is not limited to the above-described micro gas turbine, and can be used as, for example, a bearing that supports a rotor of a supercharger. As shown in FIG. 18, the supercharger drives the turbine 51 with exhaust gas generated in the engine 53, rotates the compressor 52 with the driving force to compress the intake air, and increases the torque and efficiency of the engine 53. It is intended to improve. The rotor is constituted by the turbine 51, the compressor 52, and the shaft 6, and the foil bearing 10 of each of the above embodiments can be used as the radial bearing 10 that supports the shaft 6.

  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.

6 shaft 6a outer peripheral surface 11 outer member 11a fitting groove 11b inner peripheral surface 13 foil member 13a mounting portion 15 bearing surface 16 spring portion 16a tip portion 30 belt-like foil 60 tongue piece portion C radial bearing gap

Claims (20)

And a cylindrical outer member, a shaft inserted in the inner periphery of the outer member, and a cylindrical foil member interposed between the inner peripheral surface of the outer member and the outer peripheral surface of the shaft. In a foil bearing that provides a bearing surface that forms a radial bearing gap on the member and supports relative rotation of the shaft and the outer member with a fluid film generated in the radial bearing gap.
A foil bearing comprising a single foil member provided with a bearing surface and a spring portion that elastically supports the bearing surface.   The foil bearing according to claim 1, wherein a tongue piece is formed on the foil member, and the tongue piece is plastically deformed to constitute a spring portion.   The foil bearing according to claim 2, wherein the tongue piece part is folded back along a circumferential folding line so that the spring part and the bearing surface overlap in the radial direction.   The foil bearing according to claim 3, wherein the folding line of the tongue piece is provided on both axial sides of the bearing surface.   The foil bearing according to claim 1 or 2, wherein the spring portion and the bearing surface are formed at different positions in the axial direction.   The foil bearing according to any one of claims 1 to 5, wherein the spring portions are spaced apart at a plurality of locations in the axial direction, and a bearing surface is disposed between the adjacent spring portions in the axial direction.   The foil bearing of Claim 6 which formed the spring part in two places of the axial direction.   The foil bearing of Claim 6 which formed the spring part in three places of the axial direction.   The foil bearing of any one of Claims 1-8 which provided the spring part in the several places of the circumferential direction.   The foil bearing according to any one of claims 1 to 9, wherein the foil member is formed in a cylindrical shape with an end, and one end of the foil member is fixed to the outer member.   The foil bearing according to any one of claims 1 to 9, wherein the foil member is formed in an end-cylinder shape, and one end of the foil member is fixed to the shaft.   The foil bearing according to claim 10, wherein the spring portion is disposed on the outer diameter side of the bearing surface and slidably contacts the inner peripheral surface of the outer member.   The foil bearing according to claim 11, wherein the spring portion is disposed on the inner diameter side of the bearing surface and is slidably brought into contact with the outer peripheral surface of the shaft.   The foil bearing according to claim 1, wherein a coating is formed on the bearing surface.   The foil bearing according to claim 12, wherein a coating is formed on one or both of the spring part sliding with each other and the inner peripheral surface of the outer member.   The foil bearing according to claim 13, wherein a coating is formed on one or both of the spring portion and the outer peripheral surface of the shaft that slide relative to each other.   The foil bearing according to any one of claims 14 to 16, wherein the coating reduces friction on the surface.   The foil bearing according to claim 17, wherein the film is formed of any one of a DLC film, a titanium aluminum nitride film, and a disulfide molybdenum film.   The foil bearing of any one of Claims 1-18 used for support of the rotor of a gas turbine.   The foil bearing of any one of Claims 1-18 used for support of the rotor of a supercharger.

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