JP6219489B2 - Foil bearing - Google Patents

Description

  The present invention relates to a foil bearing.

  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 such as a gas turbine or a turbocharger where the temperature changes drastically, the radial bearing gap varies due to the effect of thermal expansion, so 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. Patent Documents 4 and 5 show so-called multi-arc type foil bearings in which a plurality of foils are arranged side by side in the circumferential direction, and both circumferential ends of each foil are attached to an outer member.

JP 2002-364463 A JP 2003-262222 A JP 2009-299748 A JP 2009-216239 A JP 2006-57828 A

  In the foil bearings of Patent Documents 4 and 5 above, both ends in the circumferential direction of each foil are provided on the projecting parts (the shift restraining part 62 of Patent Document 4 and the peak 70 of Patent Document 5) projecting from the inner peripheral surface of the outer member to the inner diameter. The both ends of each foil in the circumferential direction are held by the foil holder.

  An object of the present invention is to enhance the vibration damping effect of a shaft by a multi-arc type foil bearing.

In order to achieve the above object, the present invention provides a foil bearing including an outer member and a plurality of foils attached to the inner peripheral surface of the outer member, wherein each foil has one end in the circumferential direction. One holding portion that is provided in the portion and held in contact with the outer member, and the other holding portion that is provided in the other end portion in the circumferential direction and held in contact with the outer member; A body portion having a bearing surface, which is provided between the two holding portions in the circumferential direction, and the one holding portion of each foil has a gap in one fixing groove formed on the inner peripheral surface of the outer member. The connection portion between the main body portion and the one holding portion of each foil is smoothly continuous without bending, and the one holding portion of each foil is circumferentially directed toward the outer diameter. Monodea in a state where the other hand is inclined is inserted into the one fixing groove .

  As described above, according to the foil bearing of the present invention, the vibration damping effect of the shaft due to the sliding of the foil can be enhanced by sliding the foil holding portion and the fixing groove.

It is a figure which shows notionally the structure of a gas turbine. It is sectional drawing which shows the support structure of the rotor in the said gas turbine. It is the front view which looked at the foil bearing concerning one Embodiment of this invention from the axial direction. (A) is a perspective view of the foil used with the said foil bearing, (b) is a perspective view which shows the state which combined multiple foils. It is an expanded sectional view of the foil bearing. It is an expanded view which converts the circumferential direction into the linear direction, and shows the said foil bearing. It is a figure which shows the state which the axis | shaft and foil contacted, (a) shows the case where the friction coefficient of the sliding surface of foil and an outer member is enlarged, (b) shows the case where the same friction coefficient is made small. It is an expanded sectional view of the foil bearing which concerns on other embodiment. FIG. 9 is a development view showing the foil bearing of FIG. 8 by converting the circumferential direction into a linear direction. (A) is a perspective view of the foil used with the foil bearing which concerns on other embodiment, (b) is a perspective view which shows the state which combined multiple foils. It is an expanded sectional view of the foil bearing which concerns on other embodiment. FIG. 12 is a development view showing the foil bearing shown in FIG. 11 by converting the circumferential direction into a linear direction. (A) is a perspective view of the foil used with the foil bearing which concerns on other embodiment, (b) is a perspective view which shows the state which combined multiple foils. It is a side view 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 gas turbine. This gas turbine mainly includes a turbine 1 and a compressor 2 that form blade cascades, 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 support structure for the rotor in the gas turbine. In this support structure, radial bearings 10 are disposed at two axial positions, and thrust bearings 20 and 20 are disposed on both axial sides of the flange portion 6 b of the shaft 6. The shaft 6 is supported by the radial bearing 10 and the thrust bearing 20 so as to be rotatable in the radial direction and in both thrust directions.

  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 for the gas turbine will be described with reference to the drawings.

  As shown in FIG. 3, the foil bearing 10 is fixed to an inner periphery of a housing (not shown), and an outer member 11 into which the shaft 6 is inserted and an inner peripheral surface 11 a of the outer member 11. It consists of a plurality of attached foils 13. The foil bearing 10 is a so-called multi-arc type foil bearing in which the inner peripheral surface 11a of the outer member 11 has a cylindrical surface shape, and three foils 13 are arranged in the circumferential direction on the inner peripheral surface 11a. is there. A member (for example, a back foil) for imparting elasticity to the foil 13 is not provided between the inner peripheral surface 11 a of the outer member 11 and the foil 13, and the outer diameter surface 13 c 1 of the foil 13 and the outer side are not provided. The inner peripheral surface 11a of the member 11 is directly opposed in the radial direction.

  Each foil 13 includes a holding portion 13a, 13b provided at both ends in the circumferential direction and a main body portion 13c provided between the holding portions 13a, 13b in the circumferential direction. Each foil 13 including the holding portions 13a and 13b and the main body portion 13c is integrally formed from a single foil by pressing or the like. The holding portions 13 a and 13 b are held in contact with the outer member 11. The holding portions 13a and 13b of the adjacent foils 10 are provided so as to intersect each other when viewed in the axial direction (see FIG. 3), and the holding portions 13a and 13b of the respective foils 10 are the outer diameters of the main body portions 13c of the adjacent foils 10. Arranged on the side. In the illustrated example, the holding portions 13 a and 13 b are inserted into the fixing grooves 11 b and 11 c provided on the inner peripheral surface 11 a of the outer member 11. The fixing grooves 11b and 11c are formed by wire cutting, for example, and are formed over the entire axial length of the outer member 11. At least one of the holding portions 13a and 13b is not completely fixed to the fixing grooves 11b and 11c, and is held in a slidable state. The fixed groove 11b is inclined in one circumferential direction toward the outer diameter (see the arrow in FIG. 3), and the fixed groove 11c is inclined in the other circumferential direction toward the outer diameter. The fixing grooves 11b and 11c are opened at the same circumferential position. The body 13c of the foil 13 is formed by bending a rectangular flat plate into a substantially arc shape, and has a bearing surface A on the inner diameter surface 13c2.

  As shown in FIG. 4 (a), one holding portion 13a in the circumferential direction of each foil 13 extends a partial region in the axial direction of the main body portion 13c (in the illustrated example, the central portion in the axial direction) to one circumferential direction. Consists of convex parts. On the other hand, the other holding portion 13b in the circumferential direction of each foil 13 is formed by a convex portion in which a part in the axial direction of the main body portion 13c extends in the other circumferential direction. The other holding portion 13b in the circumferential direction is composed of a plurality of (two in the illustrated example) convex portions that are spaced apart in the axial direction, and a concave portion 13b1 is provided between these axial directions. By inserting the holding portion 13a provided at one end of the foil 13 into the recess 13b1 between the holding portions 13b provided at the other end of the adjacent foil, the holding portions 13a and 13b intersect in the axial direction (see FIG. 4 (b)).

  As shown in FIG. 4 (b), one holding portion 13a of the foil 13 is inserted into the recess 13b1 provided between the axial directions of the other holding portion 13b of the foil 13 adjacent thereto, and a plurality of (illustrated examples) are inserted. The three foils 13 are attached to the inner peripheral surface 11a of the outer member 11 by inserting the holding portions 13a and 13b into the fixing grooves 11b and 11c, respectively, in a state where the three foils 10 are integrated. In this way, by holding the holding portions 13a and 13b of the adjacent foils 13 and inserting them into the fixing grooves 11b and 11c on the outer diameter side (back side) of the foil 13, the entire circumference of the inner peripheral surface 11a of the outer member 11 is obtained. Can be covered with the main body 13c of the foil 13, the area of the bearing surface can be ensured to the maximum. Further, since the circumferential end portions (holding portions 13a and 13b) of the foil 13 are not exposed on the sliding surface with the shaft 6, it is possible to reliably prevent the circumferential end portion of the foil 13 from turning to the inner diameter side.

  As shown in FIG. 5, both ends in the circumferential direction of the body portion 13c of each foil 13 (boundary portions with the holding portions 13a and 13b) do not extend along the inner peripheral surface 11a of the outer member 11, With respect to the inner peripheral surface 11a, the main body portion 13c rises toward the inner diameter side toward the center in the circumferential direction. In the illustrated example, the boundary between the circumferential ends of the main body portion 13c and the holding portions 13a and 13b is smoothly continuous without being bent, and the circumferential end portion of the main body portion 13c is curved so as to protrude toward the inner diameter. doing. As a result, a radial gap δ is formed between the outer diameter surface 13c1 of each foil 13 and the inner peripheral surface 11a of the outer member 11 at both circumferential ends of the main body 13c of each foil 13. Each foil 13 can be elastically deformed in a direction to reduce the radial gap δ. That is, the shaft 6 rotates to increase the pressure in the radial bearing gap R between the outer peripheral surface 6a of the shaft 6 and the bearing surface A of the foil 13, and the foil 13 is pushed toward the outer diameter side, so that the radial gap δ is reduced. When it becomes, it is designed so that the deformation of the foil 13 remains within the elastic range (not plastically deformed). Thus, the elastic force in the inner diameter direction is applied to the foil 13 by elastically deforming the vicinity of the end of the main body 13c of the foil 13. The elastic force applied to the foil 13 can be adjusted by the axial dimensions and number of the holding portions 13a and 13b, the arrangement location, or rising angles θ1 and θ2 at both ends of the main body portion 13c described later.

  In the present embodiment, the rising angles of both ends of the main body 13c of each foil 13 with respect to the inner peripheral surface 11a of the outer member 11 are different. The rising angle of the end portion of the main body portion 13c is a tangent at the end portion of the main body portion 13c and a point that intersects the foil 13 (that is, the opening portion of the fixing groove 11b) on the inner peripheral surface 11a of the outer member 11. Says the angle between tangents. In the present embodiment, as shown in FIG. 5, the rising angle θ1 at one end (the holding portion 13a side) of the main body 13c is larger than the rising angle θ2 at the other end (the holding portion 13b side). As described above, since the rising angles at both ends of the main body 13c are θ1> θ2, as shown in the development view of FIG. The main body 13c of each foil 13 is provided on one end side (the holding portion 13a side) with respect to the central portion O in the circumferential direction. When the shaft 6 rotates to one side in the circumferential direction (see the arrow in FIG. 6), the radial bearing gradually narrows toward the leading side in the rotational direction between the outer peripheral surface 6a of the shaft 6 and the bearing surface A of the foil 13. A gap R is formed. At this time, as described above, since the peak position P of each foil 13 is unevenly distributed on one end side, the bearing surface A that generates positive pressure is formed in a wide region on the other end side of the peak position P. The circumferential region of the bearing gap R can be made large, and the supporting force in the radial direction can be increased. In the present embodiment, since the connecting portions between the holding portions 13a and 13b of the foil 13 and the main body portion 13c are smoothly continuous, the rising angles θ1 and θ2 of the main body portion 13c are the inclination angles of the fixing grooves 11b and 11c. Almost matches.

  If the rising angles θ1 and θ2 of the main body portion 13c of the foil 13 are too large, the foil 13 is greatly pushed out toward the inner diameter side, so that the possibility of bending due to interference with the shaft 6 increases. Therefore, it is desirable to set the rising angles θ1 and θ2 to 30 ° or less, preferably 20 ° or less.

  The foil 13 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.

  In the above configuration, when the shaft 6 is rotated in one circumferential direction (the direction of the arrow in FIG. 3), that is, in the reduction direction of the wedge-shaped radial bearing gap R, the bearing surface A of each foil 13 and the outer peripheral surface 6a of the shaft 6 An air film is formed between them. When the pressure of the air film increases, the end portion of the main body portion 13c of the foil 13 is pushed into the outer diameter side, and elastically deforms in the direction in which the radial gap δ decreases. When the main body portion 13c is pushed into the outer diameter side in this way, moment force is applied to the boundary portion between the main body portion 13c and the holding portions 13a and 13b. At this time, since the holding portions 13a and 13b are inserted into the fixing grooves 11b and 11c, both surfaces of the holding portions 13a and 13b are held by the inner walls of the fixing grooves 11b and 11c. Thereby, since the angle of the holding portions 13a and 13b does not change, the rising angle of the circumferential end portion of the main body portion 13c that is continuous with the holding portion 13a is maintained, and the elastic force is efficiently generated by curving the end portion of the main body portion 13c. Can be achieved.

  A wedge-shaped radial bearing gap R is formed at a plurality of circumferential locations around the shaft 6 (three locations in the illustrated example), and the shaft 6 is supported so as to be rotatable in the radial direction in a non-contact state with respect to the foil 13. The At this time, the shape of the foil 13 is maintained at a position where the elastic force of the foil 13 and the pressure of the air film formed in the radial bearing gap R are balanced. Note that the actual radial bearing gap R has a very small width of about several tens of μm, but the width is exaggerated in FIGS. Further, due to the flexibility of the foil 13, the bearing surface A of each foil 13 is arbitrarily deformed depending on the operating conditions such as the load, the rotational speed of the shaft 6, the ambient temperature, etc. It is automatically adjusted to the appropriate width. Therefore, the radial bearing gap R 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 bearing 10, it is difficult to form an air film having a thickness equal to or greater than the surface roughness on the bearing surface A of each foil 13 and the outer peripheral surface 6 a of the shaft 6 at the time of low-speed rotation immediately before the shaft 6 is stopped or immediately after starting. Become. Therefore, a metal contact is produced between the bearing surface A of each foil 13 and the outer peripheral surface 6a of the shaft 6, thereby causing an increase in torque. In order to reduce the torque by reducing the frictional force at this time, the bearing surface A (inner diameter surface 13c2) of each foil 13 and the surface of the sliding member (in this embodiment, the outer peripheral surface 6a of the shaft 6). It is desirable to form a coating (first coating) that reduces the surface friction on either or both. As this 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 bearing surface A can be improved, and the bearing life can be increased.

  Further, during the operation of the bearing, the foil 13 is expanded in diameter under the influence of an air film formed in the radial bearing gap and is pressed against the inner peripheral surface 11a of the outer member 11, and accordingly, the foil 13 Minute sliding in the circumferential direction occurs between the outer diameter surface 13c1 and the inner peripheral surface 11a of the outer member 11, and between the holding portions 13a and 13b of the foil 13 and the fixing grooves 11b and 11c. Accordingly, one or both of the outer diameter surface 13c1 of the foil 13 and the inner peripheral surface 11a of the outer member 11 that contacts the outer diameter surface 13c1, or the holding portions 13a and 13b of the foil 13 and the fixing groove that contacts the outer surface 11c. By forming a coating (second coating) on one or both of 11b and 11c, it is possible to improve the wear resistance at these sliding portions. In the foil bearing 10 described above, since both ends in the circumferential direction of the main body portion 13c of the foil 13 are raised on the inner diameter side with respect to the inner peripheral surface 11a of the outer member 11, the outer peripheral surface 13c1 of the main body portion 13c and the outer The contact with the inner peripheral surface 11a of the side member 11 is slight. Therefore, it is effective to provide the second coating in the holding portions 13a and 13b of the foil 13 and the fixing grooves 11b and 11c in contact therewith.

  Further, the bearing characteristics can be adjusted by controlling the friction coefficient of the sliding surface between the foil 13 and the outer member 11. For example, when the friction coefficient of at least one of the sliding surfaces of the foil 13 and the outer member 11 (for example, the surfaces of the holding portions 13a and 13b of the foil 13) is increased, the outer member 11 (for example, the fixing grooves 11b and 11c) Since frictional energy due to sliding with the inner surface increases, the vibration damping effect due to rotation of the shaft 6 can be improved. In this case, as the second coating, it is preferable to use a DLC film or a titanium aluminum nitride film that has a friction coefficient larger than that of the diverted molybdenum film but is excellent in wear resistance. For example, a molybdenum disulfide film is used as the first coating formed on the bearing surface A, while a titanium aluminum nitride or DLC film is used as the second coating formed on the sliding portion between the foil 13 and the outer member 11. By making the friction coefficients of the two coatings different, it is possible to achieve both a reduction in torque and an improvement in vibration damping.

  On the other hand, when the friction coefficient of at least one of the sliding surfaces of the foil 13 and the outer member 11 (for example, the surfaces of the holding portions 13a and 13b of the foil 13) is reduced, the wear resistance of the foil 13 against contact sliding with the shaft 6 is reduced. Can increase the sex. That is, when the shaft 6 and the foil 13 come into contact with each other at the time of low speed rotation such as immediately after the rotation of the shaft 6 or just before stopping, the holding portions 13a and 13b of the foils 13 are fixed to the fixing grooves 11b and 11c of the outer member 11 by the contact pressure. Each foil 13 is deformed following the outer peripheral surface 6 a of the shaft 6. At this time, if the friction coefficient of the sliding surface between the foil 13 and the outer member 11 is large, the holding portions 13a and 13b of the foil 13 slide against the fixing grooves 11b and 11c as shown in FIG. Therefore, it is difficult for the foil 13 to follow the outer peripheral surface 6 a of the shaft 6. In this case, since the contact region T1 between the foil 13 and the outer peripheral surface 6a of the shaft 6 is reduced, the contact pressure per unit area is increased, and the foil 13 and the shaft 6 are easily worn. On the other hand, when the wear coefficient of the sliding surface between the foil 13 and the outer member 11 is small, as shown in FIG. 7B, the holding portions 13a and 13b of the foil 13 are fixed to the fixing grooves 11b and 11c. Since it is slippery, the foil 13 can easily follow the outer peripheral surface 6 a of the shaft 6. In this case, since the contact region T2 between the foil 13 and the outer peripheral surface 6a of the shaft 6 is increased, the contact pressure per unit area is reduced, and the foil 13 and the shaft 6 are not easily worn.

  The present invention is not limited to the above embodiment. In the above-described embodiment, the case where the rising angles θ1 and θ2 at the both ends of the main body portion 13c of the foil 13 are made different is shown, but the rising angles θ1 and θ2 may be made equal as shown in FIG. θ1 = θ2). In this case, as shown in FIG. 9, the peak position P is arranged at the circumferential center O of each foil 13. At this time, the foil 13 has a symmetrical shape in the circumferential direction with respect to the peak position P, and bearing surfaces A and A ′ having the same area are formed on both sides of the peak position P in the circumferential direction. Thus, when the shaft 6 rotates in one direction (see the solid line arrow in FIG. 9), the rotation direction precedes between the bearing surface A provided on the other circumferential side of the peak position P and the outer peripheral surface 6a of the shaft 6. A radial bearing gap R that is reduced toward the side is formed. On the other hand, when the shaft 6 rotates in the other direction (see the dotted arrow in FIG. 9), the rotation direction precedes between the bearing surface A ′ provided on one side in the circumferential direction of the peak position P and the outer peripheral surface 6a of the shaft 6. A radial bearing gap R ′ reduced toward the side is formed. Thus, by making the rising angles θ1 and θ2 equal, the same supporting force can be exhibited regardless of the direction in which the shaft 6 rotates.

  The embodiment shown in FIG. 10 differs from the above-described embodiment in that a slit 13d is provided at the boundary between the main body portion 13c of the foil 13 and the holding portion 13b on the other end side. The slit 13d is provided at the same axial position as the holding portion 13a on one end side of the foil 13, and the holding portion 13a can be inserted (see FIG. 10B). The holding portion 13a is inserted into the slit 13d of the adjacent foil 13, and the holding portions 13a and 13b of each foil 13 are inserted into the fixing grooves 11b and 11c of the outer member 11 in a state where the plurality of foils 13 are connected in a ring shape. Thus, the foil 13 is attached to the inner peripheral surface 11 a of the outer member 11. The axial view of the foil bearing 10 is the same as in FIG. In this case, since the holding portion 13a of the foil 13 passes through the slit 13d of the adjacent foil 13 and is inserted into the fixing groove 11b, the holding portion 13a and the slit 13d are engaged in the circumferential direction so that Movement of the end (holding portion 13b) in the circumferential direction is reliably restricted.

  In the embodiment shown in FIG. 11, the fixing groove 11 c is not provided in the outer member 11, and the holding portion 13 b on the other end side of the foil 13 is provided along the inner peripheral surface 11 a of the outer member 11. , Different from the above embodiment. Specifically, the holding portions 13a and 13b of the adjacent foils 13 are crossed in the axial direction (see FIG. 4B or FIG. 9B), and in this state, the holding portion 13a on one end side is moved outward. While being inserted into the fixing groove 11 b of the member 11, the holding portion 13 b on the other end side of the foil 13 is inserted between the adjacent foil 13 and the inner peripheral surface 11 a of the outer member 11. As a result, the holding portion 13 b on the other end side of the foil 13 is held from the inner diameter side by the adjacent foil 13 and is held in contact with the inner peripheral surface 11 a of the outer member 11. Even in this case, the bearing characteristics can be adjusted by controlling the friction coefficient of the sliding surface between the holding portion 13b of the foil 13 and the inner peripheral surface 11a of the outer member 11 as in the above embodiment. (See FIG. 7).

  In this case, the movement of the foil 13 in one circumferential direction (the direction indicated by the solid line in FIG. 11) is restricted by the holding portion 13a hitting the back of the fixing groove 11b or by the slit hitting the holding portion 13a. The On the other hand, since the foil 13 is movable in the other circumferential direction (indicated by the dotted arrow in the figure), when the shaft 6 rotates in the other circumferential direction (in the direction indicated by the dotted arrow), the foil 13 is slid by sliding with the shaft 6. May move to the other circumferential direction, and the holding portion 13a on one end side of the foil 13 may come out of the fixing groove 11b. Further, in the foil bearing 10, since the holding portion 13b on the other end side of the foil 13 is provided along the inner peripheral surface 11a of the outer member 11, as shown in FIG. 12, the other end side of the main body portion 13c is provided. The rising angle θ2 is substantially 0, and the peak position P of the foil 13 is provided at a position unevenly distributed on one end side (left side in the drawing) from the circumferential center O of the main body 13c. For this reason, when the shaft 6 rotates in one circumferential direction (in the direction of the solid line arrow), a wide area on the other end side (right side in the figure) of the outer diameter surface 13c1 of the main body portion 13c becomes the bearing surface A. Function. As described above, the foil bearing 10 is used for the purpose of supporting the shaft 6 that relatively rotates only in one circumferential direction (the direction of the solid line arrow).

  The embodiment shown in FIG. 13 is different from the above-described embodiment in that one holding portion 13a in the circumferential direction of the foil 13 is configured by a plurality of convex portions spaced apart in the axial direction. In this way, by inserting a plurality of convex portions (holding portions 13a) spaced apart in the axial direction into the fixed grooves 11b of the outer member 11, the end portions of the foil 13 are formed in the fixed grooves 11b at two locations separated in the axial direction. Since it is held, the foil 13 can be held in a balanced manner in the axial direction. In the present embodiment, similarly to the embodiment shown in FIG. 10, a slit 13d is provided at the other end of the foil 13, and the holding portion 13a is inserted into the slit 13d. Not only this but illustration is omitted, but similarly to the embodiment shown in FIG. 4, a holding portion 13 b composed of a plurality of convex portions extending from the main body portion 13 c is provided at the other end of the foil 13, and this holding is performed. One holding portion 13a may be inserted into the recess between the portions 13b. Further, the attachment of the foil 13 to the outer member 11 may be performed by inserting the holding portions 13a and 13b into the fixing grooves 11b and 11c as shown in FIG. 3, or only one holding portion 13a as shown in FIG. May be inserted into the fixing groove 11b, and the other holding portion 13b may be along the inner peripheral surface 11a of the outer member 11. Further, in FIG. 13, the convex portion constituting the holding portion 13 a is constituted by two convex portions, but not limited to this, the number of convex portions constituting the holding portion 13 a may be three or more. In this case, the same number of slits 13d as the convex portions of the holding portion 13a are provided.

  Although the case where three foils 13 are provided on the foil bearing 10 has been described above, the present invention is not limited thereto, and two or four or more foils 13 may be provided.

  Further, in the above description, the case where the shaft 6 is a rotation side member and the outer member 11 is a fixed side member is illustrated, but conversely, the shaft 6 is a fixed side member and the outer member 11 is rotated. Even in the case of the side member, the configuration of FIG. 3 can be applied as it is. However, in this case, since the foil 13 serves as a rotating member, it is necessary to design the foil 13 in consideration of deformation of the entire foil 13 due to centrifugal force.

  The application object of the foil bearing 10 according to the present invention is not limited to the gas turbine described above, and can be used as a bearing for supporting a rotor of a supercharger, for example. As shown in FIG. 14, 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 turbo machine such as a gas turbine or a supercharger, and a lubricating oil circulation system auxiliary machine is provided separately from the viewpoint of energy efficiency, which is difficult to lubricate with a liquid such as lubricating oil. Therefore, it can be used widely as a bearing for vehicles such as automobiles, which is used under the restriction that resistance due to shearing of liquid becomes a problem, and for industrial equipment.

  Each of the foil bearings described above is an air dynamic pressure bearing that uses air as a pressure generating fluid. However, the present invention is not limited to this, and other gases can be used as the pressure generating fluid, or water or oil can be used. A liquid such as can also be used. Furthermore, although the case where either one of the shaft 6 or the outer member 11 is used as a rotation-side member and the other as a fixed-side member is illustrated, both members should be used as a rotation-side member having a speed difference. You can also.

DESCRIPTION OF SYMBOLS 10 Foil bearing 11 Outer member 11b, 11c Fixing groove 13 Foil 13a, 13b Holding | maintenance part 13c Main-body part A Bearing surface O The circumferential center part P of the main-body part of a foil P Position R Radial bearing clearance delta Radial clearance (theta) 1, (theta) 2 Foil Rising angle

Claims (3)

A foil bearing comprising an outer member and a plurality of foils attached to the inner peripheral surface of the outer member,
Each foil is provided at one end in the circumferential direction and held in contact with the outer member, and is provided at the other end in the circumferential direction and in contact with the outer member The other holding part held in the circumferential direction of both holding parts, and a main body part having a bearing surface,
The one holding portion of each foil is inserted with a gap in one fixing groove formed on the inner peripheral surface of the outer member,
The connection part of the main body part and the one holding part of each foil is smoothly continuous without bending,
A foil bearing inserted into the one fixed groove in a state where the one holding portion of each foil is inclined in one circumferential direction toward the outer diameter. The foil bearing according to claim 1, wherein the other holding portion of each foil is inserted in a state having a gap in the other fixing groove formed on the inner peripheral surface of the outer member. The foil bearing according to claim 1, wherein the other holding portion of each foil is disposed between an adjacent foil and an inner peripheral surface of the outer member.

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