JP2012092967A - Foil bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the manufacturing cost and assembling cost of a component so as to reduce the cost of a foil bearing.SOLUTION: A foil bearing 10 includes a cylindrical outward member 11, a shaft 6 inserted into the inner periphery of the outward member 11, and leaves 14 arranged at a plurality of points along a circumferential direction between an inner peripheral surface 11b of the outward member 11 and an outer peripheral surface 6a of the shaft 6. A fluid film generated in a radial bearing gap supports a relative rotation between the shaft 6 and the outward member 11. At each of leaves 14, a tip end 14a constituting a free end, a base end 14b constituting a fixed end, and a bearing surface 14c forming the radial bearing gap between the tip end 14a and the base end 14b are provided. The leaves 14 are connected to one another at a connection part 15, and the leaves 14 and the connection part 15 are formed integrally by using a single foil member 13.

Description

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

  The main shaft of a gas turbine or turbocharger is driven to rotate at high speed. Moreover, the turbine blade attached to the main shaft is exposed to high temperature. Therefore, bearings that support these main shafts are required to be able to withstand severe environments such as high temperature and high speed rotation. Oil lubricated rolling bearings and hydrodynamic pressure bearings may be used as bearings for this type of application, but if lubrication with a liquid such as lubricating oil is difficult, the auxiliary equipment of the lubricating oil circulation system from the viewpoint of energy efficiency The use of these bearings is restricted under conditions such as when it is difficult to provide a separate or when resistance due to liquid shear becomes a problem. Therefore, an air dynamic pressure bearing has attracted attention as a bearing suitable for use under such conditions.

  As an air dynamic pressure bearing, one in which both the rotating side and the fixed side bearing surfaces are made of a rigid body is generally used. However, in this type of air dynamic pressure bearing, if the radial bearing clearance formed between the rotating and stationary bearing surfaces is insufficiently managed, a self-excited so-called whirl is called when the stability limit is exceeded. Easy to touch around the spindle. 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.

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

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

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

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

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

  In order to achieve the above object, the present invention provides a cylindrical outer member, a shaft inserted into the inner periphery of the outer member, a tip disposed at a plurality of locations in the circumferential direction, and a fixed end. A plurality of leaves including a base end constituting the end and a bearing surface that forms a radial bearing gap between the front end and the base end, and either the shaft or the outer member is a rotation side member, the other In the foil bearing that supports the relative rotation of the shaft and the outer member with the fluid film generated in the radial bearing gap, a plurality of gaps are provided between the inner peripheral surface of the outer member and the outer peripheral surface of the shaft. The foil member which integrally has the leaf and the connection part which connects each leaf is arrange | positioned, It is characterized by the above-mentioned.

  In this way, by connecting a plurality of leaves at the connecting portion and integrally forming the plurality of leaves and the connecting portion on the foil member, the foil member can be manufactured from a single strip-like foil. Further, if one portion of the foil member is fixed to the outer member or the shaft, each leaf can be disposed at a predetermined position between the inner peripheral surface of the outer member and the outer peripheral surface of the shaft. Therefore, compared to the case where individual leaves are attached to the outer member as in the prior art, the production cost and assembly cost of the parts can be reduced, and the cost of the foil bearing can be reduced.

  The foil member has a cylindrical shape with ends, one end side in the circumferential direction of the foil member is attached to the outer member or the shaft, the other end is a free end, and the circumferential direction of the foil member from the one end to the other end is If the direction is opposite to the direction from the proximal end of the leaf to the distal end, the foil member is not drawn by the rotation of the rotation-side member, and the foil member can be prevented from being wound around the rotation-side member.

  The integration of the plurality of leaves and the connecting portion is, for example, (1) by connecting the base ends of the plurality of leaves with the connecting portion, or (2) of two adjacent leaves, the tip of one leaf and the other This can be done by connecting the base end of the leaf with a connecting portion.

  The foil bearing having the configuration (1) includes, for example, a double foil portion including a first foil and a second foil that are overlapped in the radial direction. The first foil is formed on the first foil, and the second foil is formed on the second foil. What formed the 2nd leaf can be considered. In this case, the first leaf and the second leaf are formed by the notches provided in the first foil and the second foil, respectively, and the first leaf is adjacent to the first leaf through the opening of the second foil formed by the notch. If it arrange | positions between two leaves, a 1st leaf and a 2nd leaf can be partially overlapped in radial direction. Therefore, it is possible to form a radial bearing gap that is continuous in the circumferential direction, and it is possible to elastically support the bearing surface of each leaf with another leaf.

  The double foil portion can be formed by rotating one foil member twice around the axis. Alternatively, the double foil portion may be formed by overlapping two cylindrical foil members in the radial direction.

  In the foil bearing having the configuration (2), the leaf and the connecting portion can be formed by mountain fold and valley fold of the foil member.

  By making the foil member slidable in the circumferential direction with respect to the member on the fixed side, the degree of freedom of deformation of the bearing surface is increased, and the vibration damping effect can be enhanced. In this case, considering the vibration damping effect of the foil member, it is desirable to increase the friction coefficient to some extent at this sliding portion. If the first coating is formed on either one or both of the sliding portion of the foil member relative to the stationary member and the sliding portion of the stationary member relative to the foil member, by appropriately selecting the coating material, Regardless of the material of the foil member or the outer member, it is possible to obtain an optimum frictional force at both sliding portions, and the degree of freedom in bearing design is increased.

  In a low-speed rotation state immediately after starting or immediately after stopping, a member that faces the bearing surface of each leaf through a radial bearing gap comes into sliding contact. By forming a second coating on the bearing surface that reduces the friction of the surface, it is possible to reduce the torque by reducing the friction torque immediately after starting and immediately after stopping. Further, the bearing surface can be protected and wear of the bearing surface during sliding contact can be suppressed.

  The first film and the second film are preferably formed of materials having different friction coefficients. As the first film and the second film, any one of a DLC film, a titanium aluminum nitride film, and a diverted molybdenum film can be selected. Since the DLC coating and the titanium aluminum nitride coating are hard coatings, if they are used, in addition to reducing friction, it is possible to increase the bearing life by improving wear resistance.

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

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

It is a figure which shows notionally the structure of a micro gas turbine. It is sectional drawing which shows the support structure of the rotor in the said micro gas turbine. It is a front view which shows one Embodiment of the foil bearing concerning this invention. It is a perspective view of the foil member used with the foil bearing shown in FIG. (A) The figure is a top view of the strip | belt-shaped foil which formed the notch | incision, (b) The figure is a side view of the foil which bent the tongue piece part after the notch formation. (A) The figure is sectional drawing which expands and shows the area | region X in FIG. 3, (b) The figure is sectional drawing which expands and shows the area | region Y in FIG. It is a front view which shows other embodiment of the foil bearing concerning this invention. FIG. 8 is a perspective view of a foil assembly used in the foil bearing shown in FIG. 7. It is a perspective view which shows the 1st foil member of the foil assembly shown in FIG. It is a perspective view which shows the 2nd foil member of the foil assembly shown in FIG. It is a front view which shows other embodiment of the foil bearing concerning this invention. It is a front view which shows other embodiment of the foil bearing concerning this invention. It is a perspective view of the foil bearing shown in FIG. (A) A figure is a top view which shows the folding process of a strip | belt-shaped foil, (b) A figure is the same side view. It is a front view which shows other embodiment of the foil bearing concerning this invention. It is a front view which shows schematic structure of a foil bearing, (a) A figure shows the case where the action direction of sliding force P and the rotation direction of a foil member are made into the same direction, (b) A figure shows the case where it reverses. It is a perspective view which shows other embodiment of a foil member. It is a front view of the foil member shown in FIG. FIG. 6 is a perspective view showing another embodiment of a foil assembly. FIG. 20 is a front view of the foil assembly shown in FIG. 19. It is a perspective view which shows the assembly process of the foil assembly shown in FIG. It is a perspective view which shows other embodiment of a foil member. It is a front view of the foil member shown in FIG. It is a figure which shows notionally the structure of a supercharger.

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

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

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

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

  Hereinafter, the structure of the leaf type foil bearing 10 suitable for the radial bearing 10 for the micro gas turbine will be described with reference to FIGS.

  As shown in FIG. 3, the leaf type foil bearing 10 includes a cylindrical outer member 11 fixed to an inner periphery of a housing (not shown), a shaft 6 inserted into the inner periphery of the outer member 11, The cylindrical foil member 13 is interposed between the inner peripheral surface of the side member 11 and the outer peripheral surface of the shaft 6.

  The foil member 13 has a cylindrical shape in which one strip-shaped foil is made to circulate around the axis 6 and has a plurality of leaves 14 at a plurality of locations in the circumferential direction. Both ends 13b and 13c of the foil member 13 are at substantially the same position in the circumferential direction, one end 13b is attached to the outer member 11, and the other end 13c constitutes a free end.

  The foil member 13 is formed with a double foil portion W in which the foils are doubled in the radial direction over substantially the entire circumference. In the foil bearing of this embodiment, as shown in FIGS. 3 and 4, the foil member 13 is rotated twice around the shaft 6, whereby the double foil portion W is formed by one foil member 13. Of the double foil portions W, the outer foil F1 (first foil) is partially raised to the inner diameter side to form the first leaf 141 constituting one of the two types of leaves 14, and the inner foil. A second leaf 142 constituting another leaf 14 is formed by partially raising F2 (second foil) toward the inner diameter side. The first leaf 141 and the second leaf 142 are alternately arranged in the circumferential direction except for the vicinity of both end portions 13b and 13c of the foil member 13.

  Each leaf 14 has a distal end 14a constituting a free end and a proximal end 14b constituting a fixed end. A bearing surface 14c is formed on the inner peripheral surface between the distal end 14a and the base end 14b of each leaf 14 so that the outer diameter side is convex. The bearing surface 14c and the outer peripheral surface 6a of the shaft 6 are A wedge-shaped radial bearing gap C that decreases in the rotational direction of the shaft 6 is formed therebetween. The distal end 14a side of each leaf 14 is on the inner diameter side of another leaf 14 adjacent to the leading side in the rotational direction, and overlaps with the proximal end 14b side of the other leaf 14 in the radial direction.

  The foil member 13 is formed of a belt-like foil having a thickness of about 20 μm to 200 μm made of a metal having a good spring property and good workability, such as a steel material or a copper alloy. In an air dynamic pressure bearing using air as a fluid film as in the present embodiment, since no lubricating oil exists in the atmosphere, the antirust effect by the oil cannot be expected. Typical examples of steel materials and copper alloys include carbon steel and brass, but general carbon steel is susceptible to corrosion due to rust, and brass may cause cracks due to processing strain (in brass) This tendency increases as the Zn content increases.) Therefore, it is preferable to use a stainless steel or bronze foil as the belt-like foil.

  Hereinafter, the manufacturing procedure of the foil member 13 shown in FIG. 4 will be described. Note that the terms “axial direction”, “radial direction”, and “circumferential direction” described in the following production procedure are the axial direction in a state in which the foil member 13 after production is incorporated in the inner circumference of the outer member 11, It means radial direction and circumferential direction. Specifically, the direction along the short side of the strip-shaped foil 30 that is a material is the “axial direction”, the direction along the long side is the “circumferential direction”, and the thickness direction is the “radial direction”.

  As shown in FIG. 5A, a belt-like foil 30 made of the metal exemplified above is prepared, and an L-shape is formed at appropriate intervals by wire cutting or pressing at a plurality of locations on one side edge thereof. A cut 38 is formed. The notch 38 includes an axial notch 38a and a circumferential notch 38b connected to the end of the axial notch 38a. By the cuts 38, a plurality of tongue pieces 34 having a flap shape are formed on one side in the axial direction of the belt-like foil 30. The region 37 between the other side edge 36 and the adjacent tongue piece 34 is left in an integrated state.

  Next, as shown in FIG. 5 (b), each tongue piece 34 is bent in the same direction along an axial fold line (shown by a broken line). Thereafter, the strip-shaped foil 30 is rolled into a double spiral shape with each tongue piece 34 being radially inward. When rolling the second roll of foil, the second roll tongue 34 is disposed between adjacent tongues 34 of the first roll. The second winding tongue 34 is inserted into the opening 35 (see FIGS. 3 and 4) formed by the first foil cut 38 and introduced between the first winding tongue 34. To do.

  The foil member 13 shown in FIG. 4 is formed by the above procedure. In the foil member 13, the second foil member 13 of the second winding becomes the first foil F <b> 1 on the outer diameter side, and the first leaf 141 is configured by the tongue pieces 34 formed on the first foil F <b> 1. Moreover, the foil member 13 of the first roll becomes the second foil F2 on the inner diameter side, and the second leaf 142 is formed by each tongue piece portion 34 formed on the second foil F2. The 1st leaf 141 protrudes between the adjacent 2nd leaf 142 through the opening part 35 of the 2nd foil F2, except the both ends 13b and 13c vicinity of the foil member 13. FIG. Therefore, the first leaf 141 and the second leaf 142 are alternately arranged in the circumferential direction except for the vicinity of both end portions 13b and 13c of the foil member 13. A region 37 between the side edge portion 36 of the belt-like foil 30 and the adjacent tongue piece portion 34 constitutes a connecting portion 15 that connects the base ends 14b of the leaves 14, and each leaf 14 is elastically deformed by the connecting portion 15. Held possible.

  The foil member 13 manufactured by the above procedure is fixed to the outer member 11 by attaching one end 13 b to the outer member 11 in a state where the foil member 13 is disposed on the inner diameter side of the outer member 1. For example, in the manufacturing process of the foil member 13 described above, an attachment portion 13a (see FIGS. 5A and 5B) standing up in the outer diameter direction is formed at one end portion of the strip-like foil 30, and this attachment portion 13a is used as the outer member. The foil member 13 can be fixed to the outer member 11 by being fitted and fixed in the fitting groove 11 a formed on the inner periphery of the outer peripheral member 11. The fixing method of the attachment part 13a to the fitting groove 11a is arbitrary, and can also be fixed by adhesion or welding. Thereafter, the shaft 6 is inserted into the inner periphery of the foil member 13 to obtain the foil bearing shown in FIG.

  In the above configuration, when the shaft 6 is rotated in the reduction direction of the wedge-shaped radial bearing gap C, an air film is formed between the bearing surface 14c of each leaf 14 and the outer peripheral surface 6a of the shaft 6. Thereby, wedge-shaped radial bearing gaps C are formed at a plurality of locations around the shaft 6 in the circumferential direction, and the shaft 6 is rotatably supported in the radial direction in a non-contact state with respect to the foil member 13 (note that The actual radial bearing gap 7 has a very small width of about several tens of μm, but the width is exaggerated in Fig. 3. Also, the inner peripheral surface 11b of the outer member 11 and the first foil F1 are drawn. And the gap between the first foil F1 and the second foil F2 is also exaggerated). Further, since the bearing surface 14c of each leaf 14 is arbitrarily deformed according to the operating conditions such as the load, the rotational speed of the shaft 6, the ambient temperature, etc. due to the flexibility of the foil member 13, the radial bearing gap C is set to the operating condition. It is automatically adjusted to an appropriate width according to the Therefore, the radial bearing gap 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 according to the present invention, each leaf 14 is connected by the connecting portion 15, and each leaf 14 and the connecting portion 15 are integrally formed by the foil member 13, so that the foil member 13 is formed from one strip-like foil 30. Can be produced. Moreover, a foil bearing can be assembled only by attaching one place of the foil member 13 to the outer member 11. Therefore, compared to the case where individual leaves are attached to the outer member as in the prior art, the production cost and assembly cost of the parts can be reduced, and the cost of the foil bearing can be reduced.

  Further, since the first leaf 141 is introduced between the adjacent second leaves 142 through the opening 35 of the second foil F2, the tip 14a side of each leaf 14 is connected to another leaf adjacent to the rotation direction leading side. It is possible to overlap with the base end 14b side in the radial direction, and it is possible to form a radial bearing gap C which is continuous in the circumferential direction. By simply rotating the foil member once and cutting and raising a plurality of portions in the circumferential direction to form a leaf (the form shown in FIG. 9 or FIG. 10), the overlap between the leaves 14 cannot be formed.

  In the foil bearing, it is difficult to form an air film having a thickness greater than the surface roughness on the bearing surface 14c of each leaf 14 and the outer peripheral surface 6a of each shaft 6 at the time of low-speed rotation immediately before the shaft 6 is stopped or immediately after starting. . For this reason, metal contact occurs between the bearing surface 14c of each leaf 14 and the outer peripheral surface 6a of the shaft 6, thereby increasing torque. In order to reduce the torque by reducing the friction force at this time, as shown in FIG. 6A, it is desirable to form a coating 17 (second coating) on each bearing surface 14c to reduce the friction of the surface. . As the second film 17, for example, a DLC film, a titanium aluminum nitride film, or a molybdenum disulfide film can be used. The DLC film, titanium or aluminum nitride film can be formed by CVD or PVD, and the molybdenum disulfide film can be easily formed by spraying. In particular, since the DLC film and the titanium aluminum nitride film are hard, the wear resistance of the bearing surface 14c can be improved and the bearing life can be increased by forming a film with these films.

  Further, during the operation of the bearing, the foil member 13 is expanded in diameter as a whole due to the influence of the air film formed in the radial bearing gap, and the first foil F1 outside the double foil portion W is inside the outer member 1. It contacts the peripheral surface 11b, and a minute sliding in the circumferential direction occurs at this contact portion. As shown in FIG. 6 (b), either the outer peripheral surface of the sliding portion, that is, the first foil F1 of the double foil portion W, and the inner peripheral surface 11b of the outer member 1 in contact therewith, By forming the coating film 16 (first coating film) on both sides (in the drawing, the case where the first coating film 16 is formed on the outer peripheral surface of the first foil F1 is illustrated), the wear resistance at this sliding portion is improved. Can be planned.

  In addition, in order to improve the vibration damping action, a certain amount of frictional force may be required at the sliding portion, and the first coating 16 is not required to have a very low frictional property. Accordingly, as the first coating 16, it is preferable to use a DLC film, titanium, or aluminum nitride film that has a friction coefficient larger than that of the diverted molybdenum film but is excellent in wear resistance. For example, while using a disulfide molybdenum film as the second film 17 formed on the bearing surface 14c, a DLC film or the like is used as the first film 16 formed on the sliding portion of the foil member 13 and the outer member 11, By making the friction coefficients of the films 16 and 17 different, it is possible to achieve both a reduction in torque and an improvement in vibration damping.

  In the above description, the case where the shaft 6 is the rotation side member and the outer member 11 is the fixed side member is illustrated. On the contrary, the shaft 6 is the fixed side member and the outer member 11 is the rotation side member. 3 can also be applied as it is. However, in this case, since the foil member 13 serves as a rotation side member, it is necessary to design the foil member 13 in consideration of deformation of the entire foil member 13 due to centrifugal force.

  3 illustrates the case where the foil member 13 is fixed to the outer member 1, but the foil 13 can also be fixed to the shaft 6. FIG. 11 shows an example in which the attachment portion 13 a at one end of the foil member 13 protrudes toward the inner diameter side and is fitted and fixed to the fitting groove 6 b provided on the shaft 6. In addition to this, the attachment portion 13a may be fixed to the shaft 6 by adhesion or welding.

  In the foil bearing 10 of the embodiment shown in FIG. 11, as in the embodiment shown in FIGS. 3 and 4, two foils F <b> 1 and F <b> 2 are overlapped in the radial direction by rotating one foil member 13 twice. A double foil portion W is formed. The tongue piece 34 provided on the first foil F1 outside the double foil W is formed with a first leaf 141 having an outer diameter side distal end 14a as a free end and an inner diameter side proximal end 14b as a fixed end. The second leaf 142 having the outer diameter side distal end 14a as a free end and the inner diameter side proximal end 14b as a fixed end is formed by the tongue piece portion 34 provided on the inner second foil F2.

  The bearing surface 14 c is formed on the outer peripheral surface of each leaf 14 (the first leaf 141 and the second leaf 142), and a wedge-shaped radial bearing gap C is formed between the bearing surface 14 c and the inner peripheral surface 11 b of the outer member 11. Is formed. During the operation of the bearing, the foil member 13 is reduced in diameter due to the air film formed in the radial bearing gap C, and the second foil F2 inside the double foil portion W contacts the outer peripheral surface 6a of the shaft 6. To do. In this contact portion, minute sliding in the circumferential direction occurs during the operation of the bearing, and therefore, either or both of the sliding portion of the inner peripheral surface of the second foil F2 and the outer peripheral surface 6a of the shaft 6 are shown in FIG. The first coating film 16 shown in (b) is formed. A second coating 17 shown in FIG. 6A can also be formed on each bearing surface 14c.

  In FIG. 11, the outer member 11 is the rotating side, but the outer member 11 may be the fixed side. However, if the outer member 11 is on the fixed side, the foil member 13 is on the rotating side. Therefore, it is necessary to consider the deformation of the first leaf 141 and the second leaf 142 due to centrifugal force when designing the foil member 13.

  In each of the embodiments described above, the double foil portion W is formed by rotating the single foil member 13 twice, but in the embodiment described below, two foils rolled in a cylindrical shape are formed. The double foil part W is formed by fitting the foil member 13 coaxially. Hereinafter, this embodiment will be described with reference to FIGS.

  In the leaf type foil bearing 10 shown in FIG. 7, a foil assembly including two cylindrical foil members 131 and 132 is disposed between the inner peripheral surface 11 b of the outer member 11 and the outer peripheral surface 6 a of the shaft 6. . The first foil member 131 and the second foil member 132 are formed with a cut 38 in the metal belt-like foil 30 (see FIG. 5 (a)), like the foil member 13 shown in FIGS. It is manufactured through a series of processes of bending the portion 34 (see FIG. 5B) and rolling the strip-like foil 30. Both foils 131 and 132 have the same shape, and an attachment portion 13a is formed at one end. The number of turns for rolling the belt-like foil 30 is one, and both end portions 13b and 13c are arranged at substantially the same position in the circumferential direction.

  Through the above steps, a first foil member 131 shown in FIG. 9 and a second foil member 132 shown in FIG. 10 are obtained. The tongue piece portion 34 of the first foil member 131 constitutes the first leaf 141, and the tongue piece portion 34 of the second foil member 132 constitutes the second leaf 142. Further, in both foil members 131 and 132, the connecting portion 15 is formed by the region 37 between the side edge portion 36 of the belt-like foil 30 and the adjacent tongue piece portion 34. In the 1st foil member 131, the base end 14b of the 1st leaf 141 is connected by the connection part 15, and each 1st leaf 141 and the connection part 15 are integrally formed. In the second foil member 132, the base end 14 b of the second leaf 142 is connected by the connecting portion 15, and each second leaf 142 and the connecting portion 15 are integrally formed.

  As shown in FIGS. 9 and 10, the other end 13 c of the first foil member 131 and the second foil member 132 is not provided with the notch 38, but the end portion thereof is bent so that the first leaf 141 and A second leaf 142 can also be formed.

  The foil assembly shown in FIG. 8 has the second foil member 132 in a state where the circumferential phase between the first foil member 131 and the second foil member 132 is shifted by ½ of the leaf pitch of one foil member. Is fitted to the inner periphery of the first foil member 131. At this time, the first leaf 141 and the second leaf 142 are circularly introduced by introducing the first leaf 141 of the first foil member 131 between the adjacent second leaves 142 through the opening 35 of the second foil member 132. They can be arranged alternately in the circumferential direction. The double foil part W is comprised by the 1st foil member 131 and the 2nd foil member 132 which overlapped in the radial direction.

  The foil assembly is attached to the outer member 1 by, for example, fitting and fixing the attachment portions 13a of the foil members 131 and 132 into two fitting grooves 11a formed on the inner periphery of the outer member 11, respectively. .

  When the shaft 6 inserted in the inner periphery of the foil assembly is rotated in the reduction direction of the wedge-shaped radial bearing gap C, the bearing surface 14c of each leaf 14 (first leaf 141 and second leaf 142) and the outer peripheral surface 6a of the shaft 6 An air film is formed between them, and wedge-shaped radial bearing gaps C are formed at a plurality of locations around the shaft 6 in the circumferential direction. As described above, the shaft 6 may be the rotation side member and the outer member 11 may be the fixed side member. Conversely, the shaft 6 may be the fixed side member and the outer member 11 may be the rotation side member. Moreover, you may attach the foil assembly shown in FIG. 8 to the axis | shaft 6 by employ | adopting the structure according to embodiment shown in FIG.

  This leaf type foil bearing can be assembled by simply manufacturing two foil members 131 and 132 and attaching each of them to the outer member 11, so that each leaf is attached to the outer member as in the prior art. Compared to the case, the production cost and assembly cost of the parts can be reduced, and the cost of the foil bearing can be reduced. Other functions and effects are also common to the embodiment shown in FIGS.

  In each embodiment described above, the base end 14b of each leaf 14 is connected by the connecting portion 15 so that each leaf 14 and the connecting portion 15 are integrally formed. In addition, of the two adjacent leaves, the leaf tip 14a of one leaf and the leaf base end 14b of the other leaf are connected by the connecting portion 15 so that each leaf 14 and the connecting portion 15 are integrally formed. You can also Hereinafter, the configuration of this embodiment will be described with reference to FIGS.

  As shown in FIGS. 12 and 13, in the foil bearing 10 of this embodiment, the foil member 13 is formed in a cylindrical shape by repeating mountain folding and valley folding a plurality of times in the circumferential direction. Between the mountain fold portion and the valley fold portion of the foil member 13, a long portion 133 having a long circumferential length and a short portion 134 having a short circumferential length are provided. The inner diameter end of the long portion 133 is mountain-folded when viewed from the inner diameter side, and the outer diameter end of the long portion 133 is valley-folded when viewed from the inner diameter side. Adjacent long portions 133 partially overlap in the radial direction, and a short portion 134 that connects them is interposed in the overlapping portion. The long portion 133 includes a bearing surface 14 c that faces the outer peripheral surface 6 a of the shaft 6, and a wedge-shaped radial bearing gap is formed between the bearing surface 14 c and the outer peripheral surface 6 a of the shaft 6. The long portion 133 having the bearing surface 14 c functions as the leaf 14. In this case, the inner diameter end of the long portion 133 constitutes the distal end 14a, and the outer diameter end of the long portion 133 constitutes the proximal end 14b. The short portion 134 constitutes the connecting portion 15 that connects the distal end 14 a of the leaf 14 and the proximal end 14 b of the adjacent leaf 14.

  As shown in FIG. 14 (a), the foil member 13 shown in FIGS. 12 and 13 is formed by alternately forming a metal strip-like foil 30 with a mountain fold 135 and a valley fold 136 in the longitudinal direction. It is manufactured by folding and then bending the belt-like foil 30 into a cylindrical shape in the direction of the arrow in the figure. Thereby, the several leaf 14 and the connection part 15 can be integrally formed by the foil member 13 of 1 sheet.

  The foil member 13 is fixed to the outer member 11 by attaching one end 13 b to the inner periphery of the outer member 11 in a state of being disposed on the inner diameter side of the outer member 11. For example, in the manufacturing process of the foil member 13 described above, an attachment portion 13a standing in the outer diameter direction is formed at one end portion of the belt-like foil 30 (see FIGS. 14A and 14B), and this attachment portion 13a is used as the outer member. The foil member 13 can be fixed to the outer member 11 by being fitted and fixed in the fitting groove 11 a formed on the inner periphery of the outer peripheral member 11. The fixing method of the attachment part 13a to the fitting groove 11a is arbitrary, and can also be fixed by adhesion or welding. Then, the foil bearing shown in FIG. 12 is obtained by inserting the shaft 6 into the inner periphery of the foil member 13.

  The other end 13c in the circumferential direction of the foil member 13 extends to the vicinity of one end 13b in the circumferential direction, and slidably contacts the inner peripheral surface of the one end 13b (this contact portion is represented by reference numeral S). Further, the base end 14b of each leaf 14 is not fixed to the inner peripheral surface 11b of the outer member 11, and can slide on the inner peripheral surface 11b in the circumferential direction. Thereby, the bearing surface 14 c of each leaf 14 is elastically supported with respect to the outer member 11.

  In the above configuration, when the shaft 6 is rotated in the reduction direction of the wedge-shaped radial bearing gap C, an air film is formed between the bearing surface 14c of each leaf 14 and the outer peripheral surface 6a of the shaft 6. As a result, as shown in FIG. 12, wedge-shaped radial bearing gaps C are formed at a plurality of circumferential positions around the shaft 6, and the shaft 6 can rotate in the radial direction in a non-contact state with respect to the foil member 13. Supported by Further, since the bearing surface 14c of each leaf 14 is arbitrarily deformed according to the operating conditions such as the load, the rotational speed of the shaft 6, the ambient temperature, etc. due to the flexibility of the foil member 13, the radial bearing gap C is set to the operating condition. It is automatically adjusted to an appropriate width according to the Therefore, the radial bearing gap can be managed to the optimum width, and the shaft 6 can be supported stably.

  In the present invention, since a plurality of leaves 14 and connecting portions 15 are formed from a single foil member 13, the manufacturing cost and assembly cost of parts are compared to the case where individual leaves are attached to the outer member as in the prior art. The cost of the foil bearing can be reduced.

  In addition, the bearing surface 14 c is elastically supported by the connecting portion 15, the other end 13 c of the foil member 13 is slidable with respect to the one end 13 b at the contact portion S, and the expansion and contraction deformation of the foil member 13 is performed. The ability to self-adjust the width of the radial bearing gap C is enhanced because the base end 14b of each leaf 14 is slidable with respect to the inner peripheral surface 11b of the outer member 11 and the like. In addition, a vibration damping effect can be obtained. Therefore, the radial bearing gap can be managed to the optimum width even under severe operating conditions such as high temperature and high speed rotation, and the shaft 6 can be stably supported. The elastic support force of the bearing surface 14c can be arbitrarily adjusted by changing the length and inclination of the connecting portion 15, and the degree of freedom in bearing design is expanded.

  In the foil bearing described above, as in the embodiment shown in FIGS. 3 and 4, the second coating 17 (see FIG. 6A) for reducing the friction surface is formed on the bearing surface 14c. By forming the first coating 16 (see FIG. 6B) on either or both sliding portions of the base end 14b of the leaf 14 and the inner peripheral surface 11b of the outer member 11 in contact therewith, Similar effects can be obtained.

  The foil member 13 having the coatings 16 and 17 on the sliding portions of the bearing surface 14c and the base end 14b of the leaf 14 forms a coating on the entire surface of one or both of the front and back surfaces in the state of the strip-like foil 30 before folding. Then, as shown in FIGS. 14A and 14B, the belt-like foil 30 can be folded at a low cost. When folded, the coating may peel off or drop off at the top end portion of the mountain fold portion 135 or the valley fold portion 136 in particular, but these top end portions are not portions that slide directly with the counterpart member. There is no problem in function. In addition, if the increase in production cost is not a problem, the first coating 16 and the second coating 17 can be formed after the strip-like foil 30 is folded.

  Further, in the embodiment shown in FIG. 12, 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 can also be made into a rotation side member. However, in this case, since the foil member 13 serves as a rotation side member, it is necessary to design the foil member 13 in consideration of deformation of the entire foil member 13 due to centrifugal force.

  In the embodiment shown in FIGS. 12 and 13, the foil member 13 is fixed to the outer member 11. However, the foil member 13 can be fixed to the shaft 6. FIG. 15 shows an example in which the attachment portion 13 a at one end of the foil member 13 protrudes toward the inner diameter side of the bearing surface 14 c and is fitted and fixed in a fitting groove 6 b provided in the shaft 6, for example. In addition to this, the attaching portion 13a may be fixed to the shaft 6 by adhesion or welding. In the foil member 13, the leaf 14 and the connecting portion 15 are integrally formed by repeating the mountain fold and the valley fold. The outer diameter end of each leaf 14 becomes the distal end 14a, and the inner diameter end of each leaf 14 becomes the proximal end 14b. The other end 13c in the circumferential direction of the foil member 13 is slidably in contact with the outer diameter side of the one end 13b of the foil member 13 (the contact portion is represented by a symbol S). The bearing surface 14 c is formed on the outer peripheral surface of each leaf 14, and a wedge-shaped radial bearing gap C is formed between the bearing surface 14 c and the inner peripheral surface 11 b of the outer member 11. The inner diameter side of the base end 14 b of each leaf 14 is slidably in contact with the outer peripheral surface 6 a of the shaft 6. In this case, the second coating 17 shown in FIG. 6A is formed on the bearing surface 14c of each leaf 14, and the first coating 16 shown in FIG. 6B is formed on the base end 14b of the leaf 14 and the outer peripheral surface of the shaft 6. 6a is formed on one or both sliding portions.

  In FIG. 15, the outer member 11 is the rotating side, but the outer member 11 may be the fixed side. However, if the outer member 11 is on the fixed side, the foil member 13 is on the rotating side. Therefore, when designing the foil member 13, it is necessary to consider deformation of the foil member 13 due to centrifugal force.

  In the foil bearing of each embodiment described above, as schematically shown in FIGS. 16 (a) and 16 (b), each leaf 14 is connected to a rotation-side member (shaft member 6 in the drawing) at the time of starting and stopping. The sliding force P in the direction from the leaf proximal end 14b to the leaf distal end 14a is received. FIGS. 16A and 16B show a case where the foil member 13 is circulated only once in order to facilitate understanding.

  In the configuration in which each leaf 14 and the connecting portion 15 are integrated as in the present invention, the sliding force P acting on each leaf 14 acts on the same foil member 13. In this case, as shown in FIG. 16A, when the circumferential direction Q from the one end 13b to the other end 13c of the foil member 13 is the same as the direction of the sliding force P, the foil member 13 rotates the shaft 6. The foil member 13 may be wound around the outer peripheral surface 6a of the shaft 6 depending on the use conditions and design conditions of the bearing.

  On the other hand, as shown in FIG. 16 (b), if the circumferential direction Q of the foil member 13 is opposite to the direction of action of the sliding force P, the foil member 13 is not caught in the rotation of the shaft. 6 can be prevented from being wound around the outer peripheral surface 6a. Therefore, it is desirable that the direction P from the leaf base end 14b of each leaf 14 to the leaf tip 14a and the circumferential direction Q from the one end 13b to the other end 13c of the foil member 13 are opposite to each other.

  FIGS. 17 to 23 show specific configurations in the case where the direction of the sliding force P and the rotating direction Q of the foil member 13 are reversed as described above in the foil bearings of the embodiments described above. It is shown. Of these, FIGS. 17 and 18 correspond to the embodiment shown in FIGS. 3 and 4 and show a case where the double foil portion W is formed by rotating one foil member 13 twice. FIGS. 19 to 21 correspond to the embodiment shown in FIGS. 7 and 8, and the double foil portion W is formed by fitting two foil members 131 and 132 coaxially (see FIG. 21). Indicates. FIGS. 22 and 23 correspond to the embodiment shown in FIGS. 12 and 13, and the base of the leaf 14 adjacent to the tip 14 a of each leaf 14 is obtained by performing multiple folds and valley folds on the foil member 13. The foil bearing which connected the end 14b with the connection part 15 is shown. In any configuration, the direction P from the base end 14b to the tip end 14a of each leaf 14 and the circumferential direction Q from the one end 13b to the other end 13c of the foil member 13 are opposite to each other. Further, it is possible to prevent the foil member 13 from being wound around the outer peripheral surface 6a of the shaft 6 at the time of stopping.

  The application target of the foil bearing 10 according to the present invention is not limited to the above-described micro gas turbine, and can be used as, for example, a bearing that supports a rotor of a supercharger. As shown in FIG. 24, the supercharger drives the turbine 51 with the exhaust gas generated in the engine 53, rotates the compressor 52 with the driving force to compress the intake air, and increases the torque and efficiency of the engine 53. It is intended to improve. The rotor is constituted by the turbine 51, the compressor 52, and the shaft 6, and the foil bearing 10 of each of the above embodiments can be used as the radial bearing 10 that supports the shaft 6.

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

  The present invention is not limited to the embodiments described above, and various modifications are possible. For example, in the above description, the case where all the leaves 14 and the connecting portions 15 are formed by one foil member 13 is illustrated, but at least two leaves 14 and the connecting portions 15 are formed by one foil member 13. Each leaf 14 may be formed by connecting a plurality of foil members 13 in the circumferential direction into a cylindrical shape.

  Each of the foil bearings described above is an air dynamic pressure bearing that uses air as a pressure generating fluid, but is not limited thereto, and may be used as an oil dynamic pressure bearing that uses lubricating oil as a pressure generating fluid. it can.

6 shaft 6a outer peripheral surface 10 foil bearing 11 outer member 11a fitting groove 11b inner peripheral surface 13 foil member 13a mounting portion 13b one end 13c other end 14 leaf 14a front end 14b base end 14c bearing surface 15 connecting portion 16 first coating 17 first coating 17 Double coating 131 Foil member 132 Foil member F1 First foil F2 Second foil 141 First leaf 142 Second leaf C Radial bearing gap P Sliding force Q Circumferential direction W Double foil portion

Claims (17)

A cylindrical outer member, a shaft inserted in the inner periphery of the outer member, and a distal end constituting a free end, a proximal end constituting a fixed end, and a distal end and a base disposed at a plurality of locations in the circumferential direction A plurality of leaves having a bearing surface that forms a radial bearing gap between the ends. In the foil bearing that supports the relative rotation of the shaft and the outer member by the generated fluid film,
A foil bearing comprising a foil member integrally including a plurality of leaves and a connecting portion for connecting the leaves between an inner peripheral surface of the outer member and an outer peripheral surface of the shaft.   The foil member has a cylindrical shape with an end, the one end side in the circumferential direction of the foil member is attached to the outer member or the shaft, the other end is a free end, and the circumferential direction of the foil member from the one end to the other end is The foil bearing according to claim 1, wherein the direction is opposite to the direction from the proximal end to the distal end of each leaf.   The foil bearing of Claim 1 or 2 which connected the base end of these leaves with the connection part.   The foil according to claim 3, comprising a double foil portion comprising a first foil and a second foil that are overlapped in the radial direction, wherein the first leaf is formed on the first foil and the second leaf is formed on the second foil. bearing.   The first leaf and the second leaf are formed by a cut provided in each of the first foil and the second foil, and the first leaf is formed in the adjacent second leaf through the opening of the second foil formed by the cut. The foil bearing of Claim 4 arrange | positioned between.   6. A foil bearing according to claim 5, wherein the double foil portion is formed by rotating one foil member twice around an axis.   The foil bearing according to claim 5, wherein the double foil portion is formed by overlapping two cylindrical foil members in the radial direction.   The foil bearing of Claim 1 or 2 which connected the front-end | tip of one leaf and the base end of the other leaf among two adjacent leaves by the connection part.   The foil bearing according to claim 8, wherein the leaf and the connecting portion are formed by a mountain fold and a valley fold of the foil member.   The foil bearing according to any one of claims 1 to 9, wherein the foil member is slidable in a circumferential direction with respect to a member on the fixed side.   The foil bearing according to claim 10, wherein a first film is formed on one or both of a sliding portion of the foil member with respect to the fixed member and a sliding portion of the fixed member with respect to the foil member.   The foil bearing of any one of Claims 1-10 which formed the 2nd film which makes the surface low friction on the bearing surface of a leaf.   The foil bearing according to claim 11, wherein a second coating for reducing friction of the surface is formed on the bearing surface of the leaf.   The foil bearing according to claim 13, wherein the first coating and the second coating are formed of materials having different friction coefficients.   The foil bearing according to claim 13 or 14, wherein any one of a DLC film, a titanium aluminum nitride film, and a diverted molybdenum film is selected as the first film and the second film.   The foil bearing of any one of Claims 1-15 used for support of the rotor of a gas turbine.   The foil bearing of any one of Claims 1-15 used for support of the rotor of a supercharger.

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