JP6305748B2 - Foil bearing, foil bearing unit having the same, and turbomachine - Google Patents

Description

  The present invention relates to a foil bearing that rotatably supports a shaft inserted in an inner periphery, a foil bearing unit having the same, and a turbomachine.

  A bearing that supports a main shaft of a turbo machine such as a gas turbine or a turbocharger is required to withstand a severe environment such as high temperature and high speed rotation. As a bearing suitable for use under such conditions, a foil bearing has attracted attention. 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. When the shaft rotates, a fluid film (for example, an air film) is formed between the outer peripheral surface of the shaft and the bearing surface of the foil, and the shaft is supported in a non-contact manner.

  For example, the following Patent Documents 1 and 2 show so-called multi-arc type foil bearings in which a plurality of foils are arranged in the circumferential direction and both ends of each foil in the circumferential direction are attached to a foil holder (housing). Yes. In these foil bearings, by striking both ends in the circumferential direction of each foil against the protruding portion (the shift suppressing portion 62 of Patent Document 1 and the peak 70 of Patent Document 2) protruding from the inner peripheral surface of the foil holder to the inner diameter, Both ends in the circumferential direction of each foil are held by the foil holder.

JP 2009-216239 A JP 2006-57828 A

  In the foil bearing, an effect of attenuating the vibration of the shaft is obtained by the frictional energy of minute sliding between the foil and another member (back foil or foil holder). However, in the foil bearings of Patent Documents 1 and 2, each foil is constrained from both sides in the circumferential direction by the protrusion provided on the foil holder, and the movement of each foil in the circumferential direction on both sides is the protrusion of the foil holder. Be regulated. For this reason, the sliding amount between the foil and the other member becomes extremely small, and there is a possibility that the vibration damping effect of the shaft cannot be sufficiently obtained.

  The problem to be solved by the present invention is to increase the vibration damping effect of the shaft by the multi-arc type foil bearing.

  The present invention made to solve the above-mentioned problems includes a foil holder having a cylindrical shape, and a plurality of foils having a bearing surface and arranged side by side in the circumferential direction on the inner peripheral surface of the foil holder. A foil bearing that is supported by the foil holder at both ends in the circumferential direction and rotatably supports the shaft inserted in the inner periphery, and is provided with a recess on the inner peripheral surface of the foil holder, A partial region in the direction can be bent inside the concave portion.

  According to this foil bearing, when the shaft is rotated, a partial region in the circumferential direction of each foil is curved inside the concave portion provided on the inner peripheral surface of the foil holder. Other regions can be moved in the circumferential direction. Thereby, since the sliding amount of each foil and foil holder increases, the vibration damping effect of the shaft by the sliding of the foil can be enhanced.

  Said foil bearing can be set as the structure which inserted the edge part of the rotation direction preceding side of each foil in the said recessed part. In this case, the end of each foil in the rotational direction leading side and the concave portion are engaged in the circumferential direction, so that the movement of the foil in the rotational direction leading side can be restricted at a predetermined position. The “rotation direction” refers to the rotation direction of the shaft supported by the foil bearing (the same applies hereinafter).

  In the above foil bearing, it is preferable that the circumferential ends of adjacent foils intersect with each other in the axial direction to form an intersection, and the circumferential ends of each foil are disposed on the outer diameter side of the adjacent foil. Thereby, a bearing surface can be provided in the inner peripheral surface whole periphery of a foil holder.

  If the circumferential width of the recess formed on the inner peripheral surface of the foil holder is too small, there is a risk that the circumferential partial region of each foil cannot be curved inside the recess. Therefore, the concave portion needs to have a circumferential width that allows the bending of each foil inside. For example, when the circumferential ends of the foil are crossed as described above, the opening of the recess is arranged such that the end of the opening of the recess is on the rear side in the rotation direction with respect to the intersection. It is preferable to set the circumferential width of the part.

  In the foil bearing described above, it is preferable to provide a corner portion on the inner wall of the recess where the end portion of each foil in the rotation direction leading side abuts. In this case, the end of each foil in the rotation direction leading side abuts on the corner, so that the end of each foil in the rotation direction leading side can be disposed at a predetermined position. Thereby, since it becomes easy to control the deformation | transformation of the foil at the time of rotation of a axis | shaft, it becomes easy to obtain the bearing surface of a desired shape, and bearing performance can be stabilized.

  Each foil of the foil bearing described above is arranged approximately along the inner peripheral surface of the foil holder, and its end is inserted into the recess. At this time, in order to cause the end of the foil to abut against the corner, the corner is on or near the tangent L of the inner peripheral surface of the foil holder with the end on the rear side in the rotational direction of the opening of the groove as a contact. It is preferable to provide {see FIG. 5A}. Specifically, for example, a corner portion of the groove is provided in a region between a straight line L ′ obtained by rotating the tangent line L about the contact point by 10 ° toward the outer diameter side and the inner peripheral surface of the foil holder. Is preferred.

  If the above-mentioned foil bearing and the rotating member inserted in the inner periphery of the foil bearing are unitized as a foil bearing unit, these can be handled as a unit, and assembling to a turbomachine or the like is facilitated. The

  The above foil bearing can be suitably applied to, for example, a turbomachine.

  As described above, according to the foil bearing of the present invention, the amount of sliding between the foil and the foil holder can be increased by bending the circumferential partial region of each foil, thereby enhancing the vibration damping effect of the shaft.

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 sectional drawing of the foil bearing unit which concerns on one Embodiment of this invention integrated in the said support structure. It is sectional drawing of the radial foil bearing integrated in the said foil bearing unit. It is sectional drawing of the groove | channel vicinity of the foil holder of the said radial foil bearing, (A) shows a mode when the axis | shaft rotated when the axis | shaft has stopped. (A) is a perspective view of the foil of the radial foil bearing, and (B) is a perspective view of a state in which three foils are temporarily assembled. It is a top view of the foil of a 1st thrust foil bearing. (A) is a top view of a 1st thrust foil bearing, (B) is a top view of a 2nd thrust foil bearing. It is sectional drawing of a 1st thrust foil bearing. It is sectional drawing of a radial foil bearing, and it has converted and showed the circumferential direction to the linear direction. It is sectional drawing of the groove vicinity of the foil holder of the radial foil bearing which concerns on other embodiment, (A) shows a mode when the axis | shaft rotates, when (A) has stopped the axis | shaft. It is sectional drawing of the radial foil bearing which concerns on other embodiment. It is a top view which shows the other example of foil. It is a top view which shows the other example of foil. It is a top view which shows the other example of foil. It is a top view which shows the other example of foil. It is a top view which shows the other example of foil.

  FIG. 1 conceptually shows the configuration of a gas turbine that is a kind of turbomachine. 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 a foil bearing unit 10 that supports the rotor shaft 6 in the gas turbine. The foil bearing unit 10 includes a rotating member 20 fixed to the shaft 6, a radial foil bearing 30 that supports the shaft 6 and the rotating member 20 in the radial direction, and a first thrust that supports the shaft 6 and the rotating member 20 in the thrust direction. A foil bearing 40 and a second thrust foil bearing 50 are provided.

  As shown in FIG. 3, the rotating member 20 includes a sleeve portion 21 and a disk-like flange portion 22 that protrudes from the sleeve portion 21 to the outer diameter. The flange portion 22 is formed of, for example, a carbon fiber reinforced composite material, and the sleeve portion 21 is formed of, for example, a carbon sintered material.

  As shown in FIG. 4, a radial foil bearing 30 as a foil bearing according to an embodiment of the present invention is attached to a cylindrical (in the illustrated example, cylindrical) foil holder 31 and an inner peripheral surface of the foil holder 31. And a plurality of (three in the illustrated example) foils 32. The plurality of foils 32 are arranged on the inner peripheral surface of the foil holder 31 in the circumferential direction.

  A groove 31b as a recess is formed on the inner peripheral surface 31a of the foil holder 31. In this embodiment, the groove | channel 31b extended along an axial direction is provided in the multiple places (three places in the example of illustration) of the foil holder 31 at equal intervals in the circumferential direction. The groove 31b is provided at least in the axial region of the end (the convex part 32e described later) of the foil 32 in the rotational direction leading side. In the present embodiment, the groove 31 b is formed over the entire axial length of the foil holder 31.

  The groove 31b has a space that allows the foil 32 to bend inside. In the present embodiment, as shown in FIG. 5A, a space 31b3 is provided on the outer diameter side of the straight line connecting the end portion 31b2 and the corner portion 31b1 on the rear side in the rotation direction of the opening portion of the groove 31b. The inner wall of the groove 31b is provided with a corner portion 31b1 with which the end portion (convex portion 32e) on the leading side in the rotation direction of each foil 32 abuts. The corner 31b1 is provided on or near the tangent L of the inner peripheral surface 31a of the foil holder 31 at the end 31b2 on the rear side in the rotation direction of the opening of the groove 31b. Specifically, the corner portion 31b1 includes a straight line L ′ obtained by rotating the tangent line L by 10 ° (desirably 5 °) around the contact point (end portion 31b2), and the inner peripheral surface 31a of the foil holder 31. It is provided in the area between. In the illustrated example, the corner 31b1 is provided substantially on the tangent line L. In addition, you may provide the corner | angular part 31b1 in the area | region of the inner peripheral surface 31a side of the foil holder 31 rather than the tangent L. FIG. In this case, the angle of the end portion 31b4 on the leading side in the rotational direction of the groove 31b may be smaller than that in the illustrated example, and the end portion 31b4 may be damaged, so that the end portion 31b4 has sufficient strength. It is necessary to set the position of the corner 31b1.

  The foil holder 31 is integrally molded including the groove 31b. The foil holder 31 of this embodiment is integrally molded with a sintered metal. In this embodiment, since the circumferential dimension of the groove 31b is relatively large, the circumferential thickness of the molding die for molding the groove 31b is increased, and damage to the molding die can be prevented. When the foil bearing unit 10 is used in a relatively low temperature environment, the foil holder 31 may be molded with resin.

  As shown in FIG. 6A, each foil 32 includes a protrusion 32c provided at one end in the circumferential direction and a recess 32d provided at the other end in the circumferential direction. The convex portion 32c and the concave portion 32d of each foil 32 are provided at the same position in the axial direction. As shown in FIG. 6B, the three foils 32 can be temporarily assembled into a cylindrical shape by fitting the convex portions 32c of the respective foils 32 into the concave portions 32d of the adjacent foils 32. In this case, when viewed in the axial direction shown in FIG. 4, one end in the circumferential direction (convex portion 32c) of each foil 32 intersects with the other circumferential end of the adjacent foil 32 (convex portions 32e on both sides in the axial direction of the concave portion 32d). It will be in the state. In this state, both ends in the circumferential direction of each foil 32 are held by the foil holder 31. Specifically, the protrusion 32e at the other circumferential end of each foil 32 is inserted into the groove 31b of the foil holder 31, and the protrusion 32c at one circumferential end of each foil 32 is the outer diameter surface 32b of the adjacent foil 32. And the inner peripheral surface 31 a of the foil holder 31. In this case, the movement of the plurality of foils 32 in the rotational direction leading side is restricted by the protrusions 32e of the foils 32 striking the corners 31b1 of the grooves 31b. Movement is not regulated. Accordingly, the plurality of foils 32 can be moved in the circumferential direction with respect to the foil holder 31.

  The inner diameter surface 32a of each foil 32 functions as a radial bearing surface S1 (see FIG. 4). In the illustrated example, a multi-arc radial bearing surface S1 is formed by three foils 32. No member (back foil or the like) for imparting elasticity to the foil 32 is provided between the inner peripheral surface 31a of the foil holder 31 and each foil 32, and the outer diameter surface 32b of the foil 32 and the foil holder. The inner peripheral surface 31a of 31 can be slid. The convex portion 32c of each foil 32 is disposed on the outer diameter side of the radial bearing surface S1 of the adjacent foil 32 and functions as an underfoil portion.

  The ends of the adjacent foils 32 stick to each other in the circumferential direction. Specifically, at the intersection P {see FIG. 5B), the concave portion 32d of one foil 32 and the root portion of the convex portion 32c of the other foil 32 are engaged in the circumferential direction {FIG. B) See}. At this time, by appropriately setting the circumferential dimension A {refer to FIG. 6A) of the radial bearing surface S1 of each foil 32, a plurality of provisionally assembled foils 32 are projected to the outer diameter side to be substantially cylindrical. Each foil 32 is in a state along the inner peripheral surface 31 a of the foil holder 31.

  As shown in FIG. 3, the first thrust foil bearing 40 supports the flange portion 22 of the rotating member 20 from one side in the axial direction (right side in the figure), and includes a disc-shaped foil holder 41 and a foil holder 41. And a plurality of foils 42 fixed to the end face 41a. In the present embodiment, the foil holder 41 of the first thrust foil bearing 40 and the foil holder 31 of the radial foil bearing 30 are integrally formed.

  As shown in FIG. 7, each foil 42 of the first thrust foil bearing 40 includes a main body portion 42a, a fixing portion 42b provided on the outer diameter side of the main body portion 42a, a main body portion 42a, and a fixing portion 42b. A connecting portion 42c to be connected is integrally provided. Both the edge 42d on the rotation direction leading side and the edge 42e on the rear side in the rotation direction of the main body 42a are substantially V-shaped with the central portion protruding toward the rotation direction leading side. The central portions of the edges 42d and 42e of the main body 42a are rounded in an arc shape.

  The fixing portion 42b of each foil 42 is fixed to the outer diameter end of the end surface 41a of the foil holder 41 as shown in FIG. In the illustrated example, the fixing portions 42 b of the plurality of foils 42 are arranged on the same circumference, and the entire fixing portion 42 b is sandwiched and fixed by the ring-shaped fixing member 43 and the end surface 41 a of the foil holder 41. The plurality of foils 42 are arranged at equal pitches in the circumferential direction. In the illustrated example, the foils 42 are overlapped with a phase shifted by half of each foil 42. As shown in FIG. 9, the edge 42d on the rotational direction leading side of each foil 42 is disposed on the adjacent foil 42 (flange portion 22 side). That is, the rotation direction leading side portion of each foil 42 rides on the rotation direction rear side portion of the adjacent foil 42. Of the surface of the main body portion 42a of each foil 42, the portion that directly faces one end surface 22a of the flange portion 22 (the portion visible in FIG. 8A) functions as the thrust bearing surface S2. In addition, you may fix the fixing | fixed part 42b of each foil 42 to the foil holder 41 or the fixing member 43 by welding or adhesion | attachment.

  As shown in FIG. 3, the second thrust foil bearing 50 supports the flange portion 22 of the rotating member 20 from the other axial side (left side in the drawing). As shown in FIG. 8B, the second thrust foil bearing 50 includes a disc-shaped foil holder 51 and a plurality of foils 52 fixed to the end surface 51 a of the foil holder 51. Of the surface of the main body portion of each foil 52, the portion directly facing the other end surface 22b of the flange portion 22 (the portion visible in FIG. 8B) functions as the thrust bearing surface S3. Since the other structure of the 2nd thrust foil bearing 50 is the same as that of the 1st thrust foil bearing 40, duplication description is abbreviate | omitted.

  The foils 32, 42, 52 are formed by pressing a metal foil having a thickness of about 20 μm to 200 μm made of a metal having a high spring property and good workability, for example, a steel material or a copper alloy. In an air dynamic pressure bearing using air as a fluid film as in this embodiment, since there is no lubricating oil in the atmosphere, it is preferable to use a stainless steel or bronze metal foil.

  The foil bearing unit 10 having the above configuration is assembled in the following procedure. First, the sleeve portion 21 of the rotating member 20 is inserted into the inner periphery of the radial foil bearing 30. Then, the 2nd thrust foil bearing 50 is attached to a 1st thrust foil bearing so that the flange part 22 of the rotating member 20 may be inserted | pinched from the axial direction both sides. Specifically, the fixing member 43 attached to the foil holder 41 of the first foil bearing 40 and the fixing member 53 attached to the foil holder 51 of the second foil bearing 50 are brought into contact with each other in the axial direction. The foil holders 41 and 51 are fixed with bolts that are not used. Thus, the foil bearing unit 10 shown in FIG. 3 is completed.

  In the foil bearing unit 10 having the above-described configuration, the shaft 6 is press-fitted into the inner periphery of the rotating member 20, and part or all of the foil holders 31, 41, 51 of the foil bearings 30, 40, 50 are fixed to the housing of the gas turbine. By doing so, it is assembled to the gas turbine. In the foil bearing unit 10, the rotating member 20 is accommodated inside the bearing member constituted by the radial foil bearing 30 and the thrust foil bearings 40, 50, and these are in a state where separation between the bearing member and the rotating member 20 is restricted. Since they are integrated, the bearing member and the rotating member 20 can be handled integrally at the time of assembling to the gas turbine, and the assembling property is improved.

  When the shaft 6 rotates in one circumferential direction (the arrow direction in FIGS. 4 and 8), the radial bearing is located between the radial bearing surface S 1 of the foil 32 of the radial foil bearing 30 and the outer peripheral surface 21 a of the sleeve portion 21 of the rotating member 20. A gap is formed, and the rotary member 20 and the shaft 6 are supported in the radial direction by the pressure of the air film generated in the radial bearing gap. At the same time, between the thrust bearing surface S2 of the foil 42 of the first thrust foil bearing 40 and one end surface 22a of the flange portion 22 of the rotating member 20, and the thrust bearing surface of the foil 52 of the second thrust foil bearing 50. A thrust bearing gap is formed between S3 and the other end face 22b of the flange portion 22 of the rotating member 20, and the rotating member 20 and the shaft 6 are supported in both thrust directions by the pressure of the air film generated in each thrust bearing gap. Is done.

  At this time, due to the flexibility of the foils 32, 42, 52, the bearing surfaces S 1, S 2, S 3 of the foils 32, 42, 52 depend on the operating conditions such as the load, the rotational speed of the shaft 6, and the ambient temperature. In order to deform arbitrarily, the radial bearing gap and the thrust bearing gap are automatically adjusted to appropriate widths according to the operating conditions. Therefore, even under severe conditions such as high temperature and high speed rotation, the radial bearing gap and the thrust bearing gap can be managed to the optimum width, and the rotating member 20 and the shaft 6 can be stably supported.

  Further, in the present embodiment, the foils 32 are pushed into the rotation direction leading side by friction with the fluid (air) that flows along with the rotation of the shaft 6, and as shown in FIG. 10, each of the radial foil bearings 30. One end in the circumferential direction of the foil 32 rises from the inner peripheral surface 31 a of the foil holder 31. On the other hand, the other circumferential end of each foil 32 is disposed along the inner peripheral surface 31 a of the foil holder 31. For this reason, the top portion 32f of each foil 32 (the region closest to the outer peripheral surface of the shaft 6) is disposed on the leading side in the rotational direction with respect to the central portion of the region between the circumferential directions of the plurality of grooves 31b. As a result, the radial bearing gap formed between the foil 32 and the outer peripheral surface of the shaft 6 gradually becomes narrower toward the region where positive pressure is generated, that is, toward the leading side in the rotational direction (left side in FIG. 10). The wide area can be taken, and the supporting force in the radial direction is increased.

  In addition, the plurality of foils 32 incorporated in the foil holder 31 are adjacent to each other in the circumferential direction at the intersections, and the foils 32 are in a state along the inner peripheral surface 31 a of the foil holder 31. For this reason, the sliding contact between the foil 32 and the rotating member 20 is suppressed, and the rotational torque can be reduced.

  During operation of the bearing, the foils 32, 42, 52 are pressed against the foil holders 31, 41, 51 due to the influence of the air film formed in the bearing gap, and accordingly, a slight sliding occurs between them. The vibration of the shaft 6 can be attenuated by the frictional energy generated by the minute sliding. In the present embodiment, as shown in FIG. 5 (A), each foil 32 is actively surrounded by providing a recess (groove 31b) having a relatively wide circumferential width on the inner peripheral surface 31a of the foil holder 31. Can be moved in the direction. That is, when the shaft 6 rotates, as shown in FIG. 5B, the foil 32 is pushed to the front side in the rotational direction by friction with the fluid (air) that flows along with the rotation of the shaft 6. At this time, a circumferential partial region of each foil 32 is curved by being pushed into the groove 31b. Specifically, as the shaft 6 rotates, the tip of the convex portion 32e of the foil 32 abuts against the corner portion 31b1 of the groove 31b, and the end portion of the foil 32 including the convex portion 32e on the leading side in the rotational direction is curved. In the illustrated example, the end of each foil 32 on the leading side in the rotational direction is curved with a convex toward the outer diameter side. The end on the rotational direction leading side of each foil 32 is curved with a larger curvature than the other regions, for example, curved with a larger curvature than the inner peripheral surface 31 a of the foil holder 31. In this way, the other region of the foil 32 (circumferential region other than the convex portion 32e) moves toward the rotation direction leading side by the amount of curvature of the end of the foil 32. Thereby, since the sliding amount of the foil 32 and the foil holder 31 increases, the vibration damping effect of the shaft 6 is further enhanced.

  At this time, if the circumferential width of the groove 31b of the foil holder 31 is too small, the convex portion 32e of each foil 31 cannot be curved inside the groove 31b, and the vibration damping effect of the shaft 6 cannot be sufficiently obtained. There is a fear. Therefore, the circumferential width of the groove 31b, particularly the circumferential width of the opening of the groove 31b, needs to be set so as to allow the convex portion 32e to be curved. For example, the circumferential dimension A of the bearing surface S1 of each foil 32 It should be 5% or more of {see FIG. 6 (A)}. In the present embodiment, the circumferential width of the groove 31b is set so that the intersection P between the circumferential ends of the adjacent foils 32 is disposed in the circumferential region of the opening of the groove 31b. Specifically, the end 31b2 on the rear side in the rotation direction of the opening of the groove 31b is arranged on the rear side in the rotation direction (the left side in FIG. 5) with respect to the intersection P of the foil 32. Moreover, in this embodiment, the circumferential direction width | variety of the opening part of the groove | channel 31b is larger than the circumferential direction dimension of the convex part 32e of each foil 32. FIG. On the other hand, if the circumferential width of the groove 31b is too large, the circumferential area of the foil 32 entering the groove 31b becomes excessive, the contact area between the foil 32 and the foil holder 31 decreases, and the vibration of the shaft 6 due to these sliding movements. The attenuation effect may be reduced. Accordingly, the circumferential width of the groove 31b, in particular, the circumferential width of the opening of the groove 31b is set within a range in which the contact area of the foil 32 with the foil holder 31 can be sufficiently secured, for example, the bearing surface S1 of each foil 32. 30% or less of the circumferential dimension A.

  In the present embodiment, since the foil 32 of the radial foil bearing 30 is not fixed in the circumferential direction with respect to the foil holder 31, the sliding amount of both of them increases when the foil 32 moves in the circumferential direction with respect to the foil holder 31. Thus, the effect of damping the vibration of the shaft 6 is further enhanced. In the illustrated example, the end (convex portion 32 c) on the rear side in the rotation direction of each foil 32 is disposed between the adjacent foil 32 and the inner peripheral surface 31 a of the foil holder 31. Since it slides in the circumferential direction while being in surface contact with the peripheral surface 31a, the vibration damping effect of the shaft 6 is further enhanced.

  In addition, since the bearing surfaces S1 to S3 of the foils and the rotating member 20 are in sliding contact with each other at the time of low-speed rotation immediately before the shaft 6 is stopped or immediately after starting, a DLC film, titanium aluminum nitride is provided on one or both of them. A low friction coating such as a film, a tungsten disulfide film, or a molybdenum disulfide film may be formed. Further, in order to adjust the frictional force caused by the minute sliding between the foils 32, 42, 52 and the foil holders 31, 41, 51, either one or both of them is provided with the above-described low friction coating. It may be formed.

  The present invention is not limited to the above embodiment. Hereinafter, although other embodiment of this invention is described, the same code | symbol is attached | subjected to the location which has the same function as said embodiment, and duplication description is abbreviate | omitted.

  For example, in the above-described embodiment, the ends of the adjacent foils 32 are stuck together in the circumferential direction at the intersection P. For this reason, as shown in FIG. 5 (B), as the shaft 6 rotates, the end of each foil in the rotation direction leading side (the vicinity of the convex portion 32e) is pushed into the groove 31b to be adjacent. The end of the foil 32 on the rear side in the rotation direction (around the convex portion 32c) is also pushed into the groove 31b. As a result, the circumferential vicinity of the foil 32 (particularly the circumferential movement of the convex portion 32c) is hindered by the fact that the vicinity of the end portion on the rear side in the rotation direction of each foil 32 enters the groove 31b while curving, and the vibration of the shaft 6 is inhibited. The attenuation effect may be reduced.

  Therefore, in the embodiment shown in FIG. 11A, the end portions of the adjacent foils 32 are not engaged in the circumferential direction. Specifically, the circumferential dimension of the convex portion 32e of each foil 32 is made longer than that in the above embodiment, and the concave portion 32d is arranged behind the intersecting portion P in the rotational direction (left side in the figure). In this case, as shown in FIG. 11B, each end of the foil 32 in the rotational direction leading side (around the convex portion 32e) is pushed into the groove 31b as the shaft 6 rotates. The end of the foil 32 on the rear side in the rotation direction (periphery of the convex portion 32 c) is not pushed into the groove 31 b and is maintained in a shape along the inner peripheral surface 31 a of the foil holder 31. Thereby, the circumferential movement in the vicinity of the end portion on the rear side in the rotation direction of each foil 32 is not inhibited, and an excellent vibration damping effect can be obtained.

  The embodiment shown in FIG. 12 differs from the above-described embodiment in that both ends in the circumferential direction of each foil 32 are inserted into the grooves 31b of the foil holder 31. In this embodiment, the edge part (convex part 32e, convex part 32c) of the foil 32 which mutually cross | intersects is inserted in the common groove | channel 31b. The groove 31b is provided with a corner portion 31b1 with which one end in the circumferential direction (convex portion 32e) of each foil abuts and a corner portion 31b5 with which the other end in the circumferential direction (convex portion 32c) of each foil abuts. In this case, since the movement of each foil 32 to both sides in the circumferential direction can be restricted, the shaft 6 rotating in both directions can be supported. That is, when the shaft 6 rotates in one circumferential direction (the direction indicated by the solid line in FIG. 12), the convex portions 32e of the foils 32 abut against the corner portions 31b1 of the grooves 31b, and the convex portions 32e are curved inside the grooves 31b. {Same as FIG. 5B or FIG. 11B}. On the other hand, when the shaft 6 rotates in the other circumferential direction (in the direction of the dotted arrow in FIG. 12), the convex portions 32c of the foils 32 abut against the corner portions 31b5 of the grooves 31b, and the convex portions 32c are curved inside the grooves 31b. . As described above, the convex portion 32e or the convex portion 32c is curved inside the groove 31b, so that the sliding amount between the foil 32 and the foil holder 31 is increased similarly to the above embodiment, and the vibration damping effect of the shaft 6 is increased. can get.

  In the embodiment shown in FIG. 12, both ends in the circumferential direction of each foil 32 are in contact with the corners 31b1 and 31b5 of the groove 31b. However, the present invention is not limited to this, and the corners of the end of each foil 32 and the groove 31b. It is good also as a structure which provided the clearance gap between part 31b1, 31b5 (illustration omitted). In this case, each foil 32 is held by the foil holder 31 in a state in which the foil 32 can move in the circumferential direction, that is, in a state having play in the circumferential direction. Thereby, the sliding amount of the foil 32 and the foil holder 31 increases, and the vibration damping effect of the shaft 6 can be enhanced.

  The shape of the foil 32 of the radial foil bearing 30 is not limited to the above embodiment. The foil 32 shown in FIG. 13 is provided with a plurality (two in the illustrated example) of convex portions 32c at one end in the circumferential direction, and a plurality (two in the illustrated example) in which adjacent convex portions 32c are fitted. ) Recess 32d. The axial width of the concave portion 32d is slightly smaller than the axial width of the convex portion 32c. At the corners on both sides in the axial direction of the recess 32d, axial cuts 32f are provided. A plurality of foils 32 are formed into a cylindrical shape by inserting both ends in the axial direction of each convex portion 32c into the notches 32f of each concave portion 32d while fitting the convex portion 32c at one circumferential direction of the foil 32 into the concave portion 32d of the adjacent foil 32. Assembled.

  The foil 32 shown in FIG. 14 is obtained by extending a convex portion 32c at one end in the circumferential direction of the foil 32 of FIG. 13 in the circumferential direction. In the example of illustration, the convex part 32c is extended beyond the center of the circumferential direction of the main-body part (rectangular area | region between the circumferential directions of the convex parts 32c and 32e) of the foil 32 which adjoins. In addition, as shown in FIG. 10, the convex part 32c of the adjacent foil 32 is distribute | arranged to the outer-diameter side of radial bearing surface S1 of each foil 32 (refer dotted line). At this time, as each foil 32 rides on the convex portion 32c of the adjacent foil 32, each foil 32 has a first spring element Q1 that is convex on the outer diameter side and a first spring element Q1 that is convex on the inner diameter side. Two spring elements Q2 are formed. Therefore, by adjusting the circumferential length of the convex portion 32c of each foil 32, the position of the boundary (inflection point) between the first spring element Q1 and the second spring element Q2 of the foil 32 is adjusted. Various spring characteristics can be imparted to the bearing surface S1.

  By the way, in the foil 32 shown in FIG. 14, the part which rides on the edge (especially axial direction both ends edge) of the convex part 32c of the adjacent foil 32 swells, and there exists a possibility that this part may wear large. Therefore, as shown in FIG. 15, by providing the convex portion 32c of the foil 32 continuously over the entire axial length of the foil 32, the adjacent foil 32 does not run on the axial end edge of the convex portion 32c. The wear of the foil 32 can be suppressed. In this case, a slit 32g into which the convex portion 32e at the other circumferential end is inserted is formed at the base portion of the convex portion 32c of the foil 32.

  Further, in the foil 32 shown in FIG. 15, since the convex portion 32e is inserted into the groove 31b of the foil holder 31 and curved, the rigidity in the vicinity of the convex portion 32e is increased, so at the time of touchdown (at the time of contact with the shaft) There is a possibility that local contact (per one piece) may occur. Therefore, as shown in FIG. 16, the slit 32h is formed in the vicinity of the root portion of the convex portion 32e of the foil 32, thereby reducing the rigidity in the vicinity of the convex portion 32e and improving the one-sided contact. In the illustrated example, slits 32h extending in the circumferential direction are provided at both axial ends of the recess 32d.

  In the foil 32 shown in FIG. 17, a herringbone-shaped cut 32i is formed in the convex portion 32c of the foil 32 shown in FIG. As each foil 32 rides on the convex portion 32c of the adjacent foil 32, a step along the herringbone-shaped cut 32i is formed in the foil 32 (see the dotted line in FIG. 17). Air flows along the herringbone-shaped step and collects air toward the center in the axial direction of each cut 32i, thereby increasing the pressure of the air film (see the dotted line arrow in FIG. 17). In FIG. 17, the herringbone-shaped cuts 32i are formed in a double row, but the present invention is not limited to this and may be a single row.

  In the above embodiment, the radial foil bearing 30 and the thrust foil bearings 40 and 50 are integrated as the foil bearing unit 10 and then attached to the gas turbine. However, the present invention is not limited to this. 30, 40, and 50 may be separately attached to the gas turbine.

  The application object of the foil bearing 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. In addition, the foil bearing according to the present invention is not limited to a turbo machine such as a gas turbine or a turbocharger, and it is difficult to lubricate with a liquid such as a lubricating oil. It can be widely used as a bearing for a vehicle such as an automobile, which is used under a restriction that it is difficult to provide or resistance due to shearing of a liquid becomes a problem, and further, as a bearing 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.

6 shaft 10 foil bearing unit 20 rotating member 30 radial foil bearing (foil bearing)
31 Foil holder 31b Groove (concave)
31b1 Corner portion 32 Foil 40 First thrust foil bearing 41 Foil holder 42 Foil 43 Fixing member 50 Second thrust foil bearing 51 Foil holder 52 Foil 53 Fixing member P Intersection S1 Radial bearing surface S2 Thrust bearing surface S3 Thrust bearing surface

Claims (8)

A foil holder having a cylindrical shape and a plurality of foils having a bearing surface and arranged in the circumferential direction on the inner peripheral surface of the foil holder, and both ends in the circumferential direction of each foil are held by the foil holder. A foil bearing that rotatably supports a shaft inserted in the inner periphery,
A recess is provided on the inner peripheral surface of the foil holder, and the end of each foil in the rotation direction leading side is inserted into the recess, and the movement of the end of each foil in the rotation direction rear side to the rotation direction leading side is allowed. ,
A foil bearing characterized in that an end of each foil in the rotational direction leading side can be bent inside the recess. Adjacent foils are crossed with each other viewed in the axial direction of the cross section formed, the foil bearing according to claim 1, wherein the circumferential ends of each foil was placed on the outer diameter side of the other foil. The foil bearing according to claim 2 , wherein an end of the opening of the concave portion on the rear side in the rotational direction is arranged on the rear side in the rotational direction with respect to the intersecting portion. The foil bearing in any one of Claims 1-3 which provided the corner | angular part which the edge part of the rotation direction preceding side of each foil collided with the inner wall of the said recessed part. A straight line obtained by rotating a tangent line of the inner peripheral surface of the foil holder with the end on the rear side in the rotation direction of the opening of the concave portion as a contact point by 10 ° to the outer diameter side around the contact point, and the inner side of the foil holder The foil bearing of Claim 4 which provided the said corner | angular part in the area | region between peripheral surfaces. A foil bearing unit comprising: the foil bearing according to any one of claims 1 to 5 ; and a rotating member that is inserted into an inner periphery of the foil bearing and to which the shaft is fixed . The turbomachine provided with the foil bearing in any one of Claims 1-5 , and the axis | shaft inserted in the inner periphery of the said foil bearing. A foil bearing unit according to claim 6, and a said shaft that is fixed to an inner periphery of said rotary member, by the foil bearing, a turbomachine said rotary member and said shaft is rotatably supported.

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