JP2013032797A - Foil bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of components and reduce relative movement tolerance in a thrust direction of a shaft, in a foil bearing relatively supporting the shaft in a radial direction and the thrust direction.SOLUTION: A pair of tapered surfaces (a tapered outer peripheral surface 21a and a tapered inner peripheral surface 22a) facing to each other are provided on an outer peripheral surface of a protrusion 21 and an inner peripheral surface of an outside member 22 in the shaft 6. A foil member 23 is attached on the tapered inner peripheral surface 22a of the outside member 22, and a bearing gap S is formed between the tapered outer peripheral surface 21a of the protrusion 21 and a bearing surface A of the foil member 23.

Description

  The present invention relates to a foil bearing in which a bearing gap is formed by a bearing surface formed in a thin film foil, and a rotating member is supported by a fluid film generated in the bearing gap.

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

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

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

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

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

  However, if a foil bearing that supports the rotating member in the radial direction and a foil bearing that supports the rotating member in the thrust direction are provided separately, the number of parts increases and the cost increases.

  Further, as described above, the foil bearing can set a bearing gap larger than that of a rolling bearing or a general air dynamic pressure bearing. However, the relative movement allowance of the shaft is increased by increasing the bearing gap. In particular, when a foil bearing is used as a thrust bearing for supporting a shaft of a gas turbine or a turbocharger, if the movement allowance in the thrust direction of the shaft is large, the blade (turbine, compressor) attached to the shaft in the thrust direction Since the allowable movement amount increases, it is necessary to set a large gap in advance between the blade and the casing so that the blade does not interfere with the casing. When the gap between the blades and the casing is increased, air leaks from the gap, so that the compression rate in the compressor or the conversion efficiency in the turbine is lowered.

  SUMMARY OF THE INVENTION An object of the present invention is to reduce the number of components and reduce the relative movement allowance of a shaft in the thrust direction in a foil bearing that relatively supports the shaft in the radial direction and the thrust direction.

  In order to achieve the above object, the present invention has a flexible structure that is disposed between a shaft, an outer member having a shaft inserted into the inner periphery thereof, and an outer peripheral surface of the shaft and an inner peripheral surface of the outer member. A foil member having a bearing surface, wherein a bearing gap is formed on the bearing surface of the foil member, and a fluid film generated in the bearing gap supports a relative rotation between the shaft member and the outer member, and the outer periphery of the shaft A pair of tapered surfaces facing each other are provided on the inner peripheral surface of the surface and the outer member, a foil member is attached to one of the tapered surfaces, and a bearing gap is formed between the other tapered surface and the bearing surface.

  Thus, in the foil bearing according to the present invention, a bearing gap is formed between the bearing surface of the foil member attached to one tapered surface and the other tapered surface. In this case, since a support force is generated in the normal direction of the tapered surface, the shaft can be relatively supported in the radial direction and the thrust direction by the radial direction component and the thrust direction component of the support force. Therefore, if the above-described foil bearing is used, the number of parts can be reduced as compared with the case where the radial support bearing and the thrust support bearing are provided separately.

  Further, in the above-described foil bearing, since the bearing gap is formed in the direction inclined with respect to the thrust direction (the normal direction of the tapered surface), it is possible to suppress the allowable movement of the shaft in the thrust direction with respect to the outer member. That is, for example, as shown in FIG. 8, when a thrust bearing gap is formed between the bearing surface 102 a of the foil 102 attached to the fixing member 101 and the end surface 104 a of the flange portion 104 of the rotating shaft 103, The size X ′ of the thrust bearing gap is the allowable movement amount x ′ of the rotating shaft 103 in the thrust direction (x ′ = X ′). On the other hand, in the example shown in FIG. 9, the end surface 201a of the fixing member 201 and the end surface 204a of the flange portion 204 of the rotating shaft 203 are tapered surfaces inclined by an angle θ with respect to the axial direction. A bearing gap is formed between the bearing surface 202 a of the foil 202 attached to the end surface 204 a and the end surface 204 a of the flange portion 204. In this case, the thrust direction component of the bearing gap size X is the allowable movement amount x of the rotating shaft 203 in the thrust direction (x = X · sin θ). Therefore, when the size X ′ of the thrust bearing gap shown in FIG. 8 is equal to the size X of the bearing gap shown in FIG. 9, the example shown in FIG. Can be reduced (x <x ′). 8 and 9, the size of the bearing gaps X and X 'is exaggerated for easy understanding.

  In the foil bearing described above, the pair of first tapered surfaces facing each other on the outer peripheral surface of the shaft and the inner peripheral surface of the outer member and having a large diameter portion disposed on one axial side are opposed to each other and the other axial side If a pair of 2nd taper surfaces which arranged a large diameter part in are provided, a shaft can be supported to both thrust directions with respect to an outside member by these 1st taper surfaces and 2nd taper surfaces.

  When the shaft and the outer member rotate relative to each other, the relative peripheral speed of the pair of tapered surfaces increases toward the larger diameter side, so that the pressure generated in the bearing gap at the large diameter portion of the tapered surface is maximized. Therefore, if the first taper surface and the second taper surface are arranged side by side in the axial direction so that the respective large diameter portions are arranged on the outside in the axial direction, the axial distance (bearing span) of the large diameter portion having a high supporting force can be obtained. ) Can be increased, and the moment rigidity of the foil bearing can be increased.

  If the foil bearing as described above is used for supporting a rotor of a gas turbine or a supercharger, the allowable movement amount of the shaft in the thrust direction can be reduced. Thereby, it becomes possible to set the clearance gap between the blade | wing and casing of a turbine or a compressor small, and the compression rate in a compressor or the conversion efficiency in a turbine can be improved.

  As described above, according to the present invention, in the foil bearing that relatively supports the shaft in the radial direction and the thrust direction, the number of parts can be reduced and the relative movement allowable amount of the shaft in the thrust direction can be reduced. .

It is a figure which shows a micro gas turbine notionally. It is an axial sectional view of a foil bearing according to an embodiment of the present invention incorporated in the micro gas turbine. It is a disassembled perspective view which notched a part of said foil bearing. It is an axial orthogonal direction sectional view of the foil bearing. It is an axial sectional view of a foil bearing according to another embodiment. It is an axial orthogonal direction sectional view of the foil bearing which concerns on other embodiment. It is a figure which shows a supercharger notionally. It is sectional drawing of the foil bearing which formed the bearing clearance gap in the thrust direction. It is sectional drawing of the foil bearing which formed the bearing clearance in the direction inclined with respect to the thrust direction.

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

  FIG. 1 conceptually shows the configuration of the micro gas turbine. The micro gas turbine mainly includes a turbine 1 and a compressor 2 that form blade rows, a generator 3, a combustor 4, and a regenerator 5. The turbine 1, the compressor 2, and the generator 3 are provided with a common shaft 6 that extends in the horizontal direction, and the shaft 6, the turbine 1, and the compressor 2 constitute a rotor that can rotate integrally. Air sucked from the intake port 7 is compressed by the compressor 2, heated by the regenerator 5, and then sent to the combustor 4. The compressed air is mixed with fuel and burned, and the turbine 1 is rotated by the high-temperature and high-pressure gas at this time. The rotational force of the turbine 1 is transmitted to the generator 3 via the shaft 6, and the generator 3 rotates to generate electric power, and this electric power is output via the inverter 8. Since the gas after rotating the turbine 1 is at a relatively high temperature, the heat of the gas after combustion is regenerated by sending this gas to the regenerator 5 and exchanging heat with the compressed air before combustion. Use. 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 support structure of the rotor, particularly a support structure between the turbine 1 and the compressor 2 in the axial direction. Since this region is adjacent to the turbine 1 rotated by high-temperature and high-pressure gas, an air dynamic pressure bearing, particularly a foil bearing 10 is applied.

  The foil bearing 10 of the present embodiment includes a first bearing portion 20 and a second bearing portion 20 ′ arranged side by side in the axial direction. As shown in the exploded view of FIG. 3, the first bearing portion 20 includes an annular protrusion 21 provided to protrude from the shaft 6 to the outer periphery, an annular outer member 22 provided on the outer periphery of the protrusion 21, A foil member 23 provided between the protruding portion 21 and the outer member 22 is provided. The second bearing portion 20 has a configuration in which the first bearing portion 20 is inverted in the axial direction, and includes a protruding portion 21 ′, an outer member 22 ′, and a foil member 23 ′. In FIG. 3, a part of the foil bearing 10 in the circumferential direction is notched, but actually, as shown in FIG. 4, the protrusions 21, 21 ′ and the outer members 22, 22 ′ are all around. A continuous ring shape is formed, and the foil members 23 and 23 'are provided almost all around.

  The protruding portion 21 of the first bearing portion 20 is fixed to the outer peripheral surface 6a of the shaft 6, and the outer member 22 is fixed to the inner periphery of the casing 30 (see FIG. 2). The first bearing portion 20 has a pair of first tapered surfaces opposed to each other. In the illustrated example, the first tapered outer peripheral surface 21 a formed on the protruding portion 21 and the first tapered surface formed on the outer member 22. The inner peripheral surface 22a has a shape. The first tapered outer peripheral surface 21a and the first tapered inner peripheral surface 22a have the same inclination angle with respect to the axial direction.

  The foil member 23 has a flexible bearing surface A, and is formed in a tapered space between the first tapered outer peripheral surface 21 a of the protruding portion 21 and the first tapered inner peripheral surface 22 a of the outer member 22. Be placed. In the present embodiment, as shown in FIG. 4, the foil member 23 is fixed to the first tapered inner peripheral surface 22 a of the outer member 22 provided on the fixed side, and the first protrusion 21 provided on the rotating side is first. A bearing gap S is formed between the tapered outer peripheral surface 21 a and the bearing surface A of the foil member 23. Note that the actual width of the bearing gap S is as small as several tens of μm, but the width is exaggerated in FIG.

  The foil member 23 of this embodiment is a so-called bump foil type composed of a metal top foil 23a having a bearing surface A and a metal back foil 23b that elastically supports the top foil 23a (see FIG. 3). . The top foil 23a is formed of a single taper-shaped foil, and a bearing surface A is provided on the inner peripheral surface (see FIG. 4). The bearing surface A has a smooth tapered surface shape without holes or steps. One end 23 a 1 of the top foil 23 a is fitted and fixed in a groove 22 b formed on the inner peripheral surface 22 a of the outer member 22. The back foil 23 b is formed of a single foil having a taper shape as a whole, and is disposed between the top foil 23 a and the outer member 22. The back foil 23b is provided with a bent portion 23b1 projecting from a plurality of locations in the circumferential direction toward the outer diameter. One end 23 b 3 of the back foil 23 b is fitted and fixed in the groove 22 b of the inner peripheral surface 22 a of the outer member 22. The outer diameter end of the bent portion 23b1 of the back foil 23b is in contact with the first tapered inner peripheral surface 22a of the outer member 22, and the inner peripheral surface 23b2 of the back foil 23b is in contact with the outer peripheral surface of the top foil 23a. The top foil 23a is elastically supported from the outer periphery by the back foil 23b.

  The top foil 23a and the back foil 23b are formed of a thin film foil 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.

  The second bearing portion 20 ′ has a pair of second tapered surfaces facing each other. In the present embodiment, as shown in FIG. 2, a second tapered outer peripheral surface 21a ′ formed on the protruding portion 21 ′, and The outer member 22 ′ has a second tapered inner peripheral surface 22a ′. The first taper surface of the first bearing portion 20 has a large-diameter portion on one axial side (the turbine 1 side, the right side in the figure), and the second taper surface of the second bearing portion 20 ′ is the other axial side (compressed). A large diameter part is arranged on the machine 2 side (left side in the figure). As a result, as for the 1st taper surface and the 2nd taper surface, the large diameter part is distribute | arranged to the axial direction inner side, and the small diameter part is distribute | arranged to the axial direction outer side. Each configuration of the second bearing portion 20 ′ is obtained by inverting each configuration of the first bearing portion 20 in the axial direction. Is omitted.

  When the shaft 6 rotates in one circumferential direction, the bearing surfaces A and A ′ of the first bearing portion 20 and the second bearing portion 20 ′ of the foil bearing 10 and the tapered outer peripheral surfaces 21a and 21a ′ of the protruding portions 21 and 21 ′. The bearing gaps S and S ′ are formed between the shaft 6 and the shaft 6 is supported in a non-contact manner in both the radial direction and the thrust direction by the fluid film generated in the bearing gaps S and S ′ (see FIG. 2). In particular, when the shaft 6 is rotated parallel to the ground as shown in FIG. 2, the shaft 6 is decentered downward by its own weight with respect to the outer members 22 and 22 ′. Narrow wedge-shaped bearing gaps S and S ′ are formed. As the shaft 6 rotates, the fluid in the wedge-shaped bearing gaps S and S 'is pushed toward the narrow side, whereby the pressure of the fluid film is increased.

  At this time, due to the flexibility of the top foils 23a and 23a ′ and the back foils 23b and 23b ′, the bearing surfaces A and A ′ of the top foils 23a and 23a ′ can be used for the load, the rotational speed of the shaft 6 and the ambient temperature. Since the bearing gap S is arbitrarily deformed according to the operating conditions, the bearing gap S is automatically adjusted to an appropriate width according to the operating conditions. Therefore, the bearing gap S 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.

  Thus, by forming the bearing gaps S and S ′ between the tapered bearing surfaces A and A ′ and the tapered outer peripheral surfaces 21a and 21a ′, a fluid film generated in each bearing gap S and S ′. The shaft 6 can be supported in the radial direction and the thrust direction. Moreover, the shaft 6 can be supported in both thrust directions by providing the first taper surface and the second taper surface symmetrically in the axial direction.

  Further, since the bearing gaps S and S ′ are formed in a direction inclined with respect to the thrust direction (the normal direction of the tapered bearing surfaces A and A ′), the bearing gap is formed in the thrust direction. Thus, the allowable movement amount of the shaft 6 in the thrust direction can be reduced (see FIGS. 8 and 9). As a result, as shown in FIG. 2, the thrust direction gap T1 between the turbine 1 and the housing 31 that accommodates it in the inner periphery, and the compressor 2 and the housing 32 that accommodates it in the inner periphery. The thrust direction gap T2 can be set small, and the conversion efficiency by the turbine 1 and the compression rate by the compressor 2 can be increased.

  The foil bearing 10 has a surface on the bearing surfaces A and A ′ of the top foils 23 a and 23 a ′ and the tapered outer peripheral surfaces 21 a and 21 a ′ of the protrusions 21 and 21 ′ during low-speed rotation immediately before the shaft 6 stops and immediately after the shaft 6 starts. It becomes difficult to form an air film having a thickness greater than the roughness. Therefore, metal contact occurs between the bearing surfaces A and A 'and the tapered outer peripheral surfaces 21a and 21a', resulting in an increase in torque. In order to reduce the torque by reducing the friction force at this time, it is desirable to form a coating on the bearing surfaces A and A 'that reduces the friction of the surface. 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 surfaces A and A ′ can be improved and the bearing life can be increased by forming a film with these films. . In addition to or in addition to forming the coating film as described above on the bearing surfaces A and A ′, the coating films are formed on the tapered outer peripheral surfaces 21a and 21a ′ of the projecting portions 21 and 21 ′ facing these surfaces. May be.

  Further, during the operation of the bearing, between the back surface of the top foil 23a (the surface opposite to the bearing surface A) and the inner peripheral surface 23b2 of the back foil 23b, the bent portion 23b1 of the back foil 23b and the outer members 22, 22 Since micro-sliding occurs between the tapered inner peripheral surfaces 22a and 22a ', the wear resistance may be improved by forming the coating on the sliding part. In order to improve the vibration damping action, it may be more convenient that a certain amount of frictional force exists in the sliding portion. Therefore, the low friction property is not required for the coating of this portion. Therefore, it is preferable to use a DLC film, titanium, or an aluminum nitride film as the coating of this portion.

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

  For example, in the embodiment shown in FIG. 5, the first bearing portion 20 and the second bearing portion 20 ′ are arranged so that the large diameter portions of the first tapered surface and the second tapered surface are arranged on the outside in the axial direction. Yes. Thereby, the axial distance between the large diameter portions of the bearing gaps S and S ′ can be made larger than that in the embodiment shown in FIG. 2. Since the peripheral speed of the shaft 6 (protruding portions 21, 21 ′) with respect to the outer members 22, 22 ′ increases as the diameter of the first taper surface and the second taper surface increases, the fluid film generated in the bearing gaps S, S ′. Is the highest at the large diameter portions of the first tapered surface and the second tapered surface. Therefore, as shown in FIG. 5, by increasing the axial distance (bearing span) between the large diameter portions of the bearing gaps S and S ′, the bearing rigidity, particularly the moment rigidity of the foil bearing 10 can be increased.

  Moreover, although the case where the 1st taper surface and the 2nd taper surface were symmetrical shapes in the axial direction was shown in the above embodiment, it is not restricted to this, You may vary these inclination angles.

  Moreover, although the case where the 1st bearing part 20 and 2nd bearing part 20 'of the foil bearing 10 were comprised by the bump foil type foil bearing was shown in the above embodiment, it is not restricted to this, The 1st bearing part 20 is shown. Further, either one or both of the second bearing portion 20 ′ may be constituted by a so-called leaf type foil bearing in which a plurality of leaf foils are arranged in the circumferential direction.

  Specifically, for example, as shown in FIG. 6, a plurality of leaf foils (leafs 24) as foil members can be arranged in the circumferential direction on the tapered inner peripheral surface 22 a of the outer member 22. Each leaf 24 is formed of a metal thin film foil, with one end 24a in the circumferential direction (the rotation side of the shaft 6 (see arrow) leading side) being a free end and the other end 24b in the circumferential direction being It is fixed to the outer member 22. The fixed end 24 b of the leaf 24 is fitted and fixed in a groove 22 c formed on the inner peripheral surface 22 a of the outer member 22. A partial region on the free end 24 a side of the leaf 24 is arranged so as to overlap with the other leaf 24 in the radial direction. The surfaces on the inner diameter side of the plurality of leaves 12 constitute a smooth bearing surface A having no holes or steps, and between the bearing surface A of each leaf 24 and the outer peripheral surface 21a of the projecting portion 21 in one circumferential direction. A wedge-shaped bearing gap S having a narrower radial width is formed.

  By the way, in the bump foil type foil bearing, when the shaft 6 is rotated in parallel with the ground (see FIG. 2), the shaft 6 is decentered downward by its own weight as described above with respect to the outer members 22 and 22 ′. A wedge-shaped bearing gap is formed between them. However, for example, when the shaft 6 is rotated perpendicularly to the ground, the shaft 6 is centered on the bearing center along the tapered surface by its own weight, so that a wedge-shaped bearing gap is not formed, and the pressure of the fluid film increases. Hateful. On the other hand, in the leaf type foil bearing shown in FIG. 6, since the wedge-shaped bearing gap S is formed even when the shaft 6 is arranged at the center of the bearing, a high pressure is generated regardless of the eccentric state of the shaft 6. be able to. Therefore, it is preferable to employ a bump foil type foil bearing from the viewpoint that the number of parts can be reduced and the spring property of the back foil can be easily adjusted. On the other hand, when the shaft 6 is perpendicular to the ground or when the thrust load is larger than the radial load, it is preferable to employ a leaf type foil bearing.

  Moreover, in the above embodiment, although the foil bearing 10 was comprised with the 1st bearing part 20 which supports the axis | shaft 6 to one thrust direction, and the 2nd bearing part 20 'which supports the thrust direction other side, it showed. However, the present invention is not limited to this, and the foil bearing 10 may be configured by only one of the bearing portions.

  Moreover, although the case where foil member 23, 23 'was fixed to the member (outside member 22, 22') on the fixed side was shown in the above embodiment, contrary to this, foil member 23, 23 'is rotated. You may fix to the side member (projection part 21,21 'of the axis | shaft 6). In this case, bearing gaps S and S 'are formed between the bearing surface A of the foil members 23 and 23' and the tapered inner peripheral surfaces 22a and 22a 'of the outer members 22 and 22'. However, when the foil member is fixed to the rotating member, the foil member rotates at a high speed, and thus the foil may be deformed by centrifugal force. Therefore, from the viewpoint of avoiding deformation of the foil, it is preferable to attach the foil member to the member on the fixed side as in the above embodiment.

  Moreover, although the case where the thrust foil bearing 20 which concerns on this invention was applied to the gas turbine was shown in the above embodiment, you may apply not only to this but to a supercharger as shown, for example in FIG. This supercharger is a so-called turbocharger that sends air to the engine 63, and includes a compressor 61 and a turbine 62. The compressor 61 and the turbine 62 are connected by a shaft 6. The shaft 6 is supported by the radial foil bearing 10 and the thrust foil bearing 20 in the radial direction and in both thrust directions. In the illustrated example, the radial foil bearings 10 are provided at two locations separated in the axial direction. Air sucked from an intake port (not shown) is compressed by the compressor 61, mixed with fuel, and supplied to the engine 63. The compressed air mixed with fuel is burned by the engine 63, and the turbine 62 is rotated by the high-temperature and high-pressure gas exhausted from the engine 63. The rotational force of the turbine 62 at this time is transmitted to the compressor 61 via the shaft 6. The gas after rotating the turbine 62 is discharged to the outside as exhaust gas.

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

  The foil bearing described above can be used not only as an air dynamic pressure bearing using air as a pressure generating fluid but also as an oil dynamic pressure bearing using lubricating oil as a pressure generating fluid.

DESCRIPTION OF SYMBOLS 1 Turbine 2 Compressor 3 Generator 4 Combustor 5 Regenerator 6 Shaft 7 Intake port 8 Inverter 9 Waste heat recovery device 10 Foil bearing 20 First bearing part 20 'Second bearing part 21, 21' Protruding part 21a First taper Outer peripheral surface (first taper surface)
21a '2nd taper-shaped outer peripheral surface (2nd taper surface)
22, 22 'Outer member 22a First tapered inner peripheral surface (first tapered surface)
22a '2nd taper-shaped inner peripheral surface (2nd taper surface)
23, 23 'Foil member 23a Top foil 23b Back foil 23b1 Bending part 23b2 Connecting part A, A' Bearing surface S, S 'Bearing gap

Claims (5)

A foil member comprising: a shaft; an outer member having an inner shaft inserted therein; and a foil member having a flexible bearing surface disposed between the outer peripheral surface of the shaft and the inner peripheral surface of the outer member. Forming a bearing gap on the bearing surface, and supporting a relative rotation between the shaft member and the outer member by a fluid film generated in the bearing gap,
A pair of tapered surfaces facing each other are provided on the outer peripheral surface of the shaft and the inner peripheral surface of the outer member, and the foil member is attached to one tapered surface, and the bearing gap is provided between the other tapered surface and the bearing surface. Forming foil bearing.   A pair of first tapered surfaces facing each other on the outer peripheral surface of the shaft and the inner peripheral surface of the outer member and having a large diameter portion disposed on one side in the axial direction, and a large diameter portion disposed on the other side in the axial direction. The foil bearing according to claim 1, further comprising a pair of second tapered surfaces.   The foil bearing according to claim 2, wherein the first tapered surface and the second tapered surface are arranged side by side in the axial direction so that the respective large diameter portions are arranged on the outer side in the axial direction.   A gas turbine having the thrust foil bearing according to claim 1.   The supercharger which has a thrust foil bearing in any one of Claims 1-3.

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