WO2017169676A1

WO2017169676A1 - Foil bearing

Info

Publication number: WO2017169676A1
Application number: PCT/JP2017/009866
Authority: WO
Inventors: 純御堂前; 真人吉野
Original assignee: Ntn株式会社
Priority date: 2016-03-30
Filing date: 2017-03-13
Publication date: 2017-10-05

Abstract

A foil bearing 10 is provided with: a cylindrical foil holder 11; and a foil 12 that is attached to the inner peripheral surface 11a of the foil holder 11. The foil 12 is provided with: a main section M that is curved along the inner peripheral surface 11a of the foil holder 11; a connection section 12e that is axially continuous with the main section M and curved in the same manner as the main section M; and an engagement section 12f that is circumferentially continuous with the connection section 12e, is disposed on the outer diameter side of the inner peripheral surface 11a of the foil holder 11, and can axially engage with the foil holder 11.

Description

Foil bearing

The present invention relates to a foil bearing.

The foil bearing is configured to support a load by forming a bearing surface with a metal thin plate (foil) having low rigidity with respect to bending and allowing the deflection of the bearing surface. The foil bearing has a feature that the bearing gap is automatically adjusted to an appropriate width according to the operating conditions such as the rotational speed, load, and ambient temperature of the shaft as the foil is bent.

¡Foil bearings generally have a foil attached to the inner peripheral surface of a cylindrical foil holder. When assembling or maintaining this foil bearing, the shaft is inserted into the inner periphery of the foil bearing or pulled out from the inner periphery of the foil bearing. At this time, the shaft and the foil slide, and the foil is in the foil holder. There is a risk of shifting in the axial direction. Further, when the shaft rotates at a low speed immediately before stopping or immediately after starting, a force due to sliding with the shaft acts on the foil, and when the shaft rotates at a high speed, a shearing force due to the viscosity of the fluid flowing through the bearing gap acts on the foil. If the force acting on these foils includes an axial component, the foil may be displaced in the axial direction with respect to the foil holder.

For example, if the foil is welded and fixed to the inner peripheral surface of the foil holder, the above-mentioned problems can be prevented, but the foil may be distorted by heat during welding. Since the bearing gap formed between the bearing surface of the foil and the outer peripheral surface of the shaft is usually a minimum width of about several tens of μm, any slight distortion in the foil will adversely affect the accuracy of the bearing gap. .

For example, in Patent Document 1 below, a locking member is attached to the foil holder, and the locking member and the foil are engaged in the axial direction, thereby preventing the axial displacement of the foil and the foil holder. .

Further, in Patent Document 2 below, as shown in FIG. 22, a protruding portion 110 protruding to the outer diameter side is provided on the foil 104, and the protruding portion 110 and the foil holder are engaged in the axial direction. Specifically, the projecting portion 110 is formed by bending an extending portion obtained by extending a partial region in the circumferential direction of the foil 104 in the axial direction to the outer diameter side.

Japanese Patent Laying-Open No. 2015-143572 JP 2012-197887 A

When the locking member is attached to the foil holder like the foil bearing shown in the above-mentioned Patent Document 1, the number of parts and the number of assembling steps increase, resulting in an increase in manufacturing cost.

On the other hand, as in the foil bearing shown in Patent Document 2 (see FIG. 22), if the protrusion 110, in which a part of the foil 104 is bent to the outer diameter side, is engaged with the foil holder, the number of parts increases. Can be avoided. However, when the protruding portion 110 is formed by bending a part of the foil 104, a bent portion along the circumferential direction is formed at the inner diameter end of the protruding portion 110, so that the rigidity of the circumferential region is increased. In this case, since the rigidity of the foil 104 differs in the circumferential direction, the design of the foil 104 is complicated. In particular, if the bent portion is provided in the top foil portion having the bearing surface, the bearing surface has different rigidity in the circumferential direction, which may adversely affect the bearing performance.

Therefore, an object of the present invention is to prevent axial displacement between the foil and the foil holder without incurring high costs due to an increase in the number of parts and man-hours, and complexity of the foil design.

In order to solve the above problems, the present invention includes a cylindrical foil holder and a foil attached to the inner peripheral surface of the foil holder, and supports a shaft inserted in the inner periphery so as to be relatively rotatable. A foil bearing, wherein the foil is curved along an inner peripheral surface of the foil holder, a connection portion that is continuous with the body portion in the axial direction and is curved in the same manner as the body portion, and the connection A foil bearing is provided that includes a locking portion that is continuous with the portion in the circumferential direction, is disposed on the outer diameter side of the inner circumferential surface of the foil holder, and is engageable with the foil holder in the axial direction.

Thus, in the present invention, the main body portion and the locking portion of the foil are connected via the connecting portion that is continuous with the main body portion in the axial direction and continuous with the locking portion in the circumferential direction. Thereby, since the latching | locking part and a main-body part can be made discontinuous in an axial direction, a latching | locking part is independent of the main-body part curved in the substantially cylindrical shape along the internal peripheral surface of a foil holder. Deformable. Therefore, the locking portion can be displaced to the outer diameter side from the main body portion without affecting the shape and rigidity of the main body portion, and can be arranged on the outer diameter side from the inner peripheral surface of the foil holder. By engaging the engaging portion with the foil holder in the axial direction, it is possible to prevent the axial displacement between the foil and the foil holder.

In the foil bearing described above, the main body portion of the foil is curved along the inner peripheral surface of the foil holder, and the connecting portion of the foil is curved following the main body portion. On the other hand, since the engaging portion of the foil is discontinuous with the main body portion in the axial direction, it does not bend following the main body portion, and tries to be elastically restored to a flat plate shape that is smoothly continuous with the connecting portion. Therefore, if there is a sufficient space on the outer diameter side of the locking portion, the locking portion is arranged on the outer diameter side of the inner peripheral surface of the foil holder in a state of being smoothly connected to the connection portion. Thus, the latching | locking part can be easily arrange | positioned rather than the inner peripheral surface of a foil holder on the outer-diameter side by utilizing the elastic restoring force of a latching | locking part.

In the foil bearing described above, if the locking portions are provided at both ends of the foil in the axial direction and the foil holder is disposed between the axial directions of the both locking portions, the both locking portions and the foil holder can be oriented in any axial direction. Because of the engagement, the movement of the foil relative to the foil holder in both axial directions can be restricted.

In the above foil bearing, if a concave portion is provided at the axial end of the inner peripheral surface of the foil holder and the foil locking portion is accommodated in the axial region of the concave portion, the foil locking portion contacts other members. Damage can be prevented.

Alternatively, a recess may be provided in the axially intermediate portion of the inner peripheral surface of the foil holder, and a foil locking portion may be disposed between the side walls on both sides in the axial direction of the recess. In this case, the movement of the foil to the both sides in the axial direction relative to the foil holder can be restricted by engaging the engaging portions of the foil with the side walls on both sides in the axial direction of the recess. This recessed part can be comprised by the through-hole of radial direction, for example. In this case, during relative rotation of the shaft, external air is drawn into the inner periphery of the foil bearing, particularly the bearing gap, through the through hole of the foil holder. As a result, the amount of fluid in the bearing gap increases, the fluid pressure generated in the bearing gap increases, and the load capacity of the foil bearing increases. Moreover, a bearing surface can be cooled by supplying external air to a bearing clearance via a through-hole. At this time, if the side walls on both sides in the circumferential direction of the through hole are concave curved surfaces parallel to the axial direction, outside air is likely to be drawn into the inner circumference of the foil bearing along the concave curved surface. The amount of fluid further increases, and the load capacity of the foil bearing further increases.

For example, the main body of the foil can be provided with a bearing surface that faces the outer peripheral surface of the shaft. In this case, if the main body of the foil is provided on both sides in the axial direction of the connecting portion, the bearing surfaces provided in each main body are provided at two locations separated in the axial direction, so that both bearing surfaces are continuous in the axial direction. The moment stiffness of the foil bearing increases more than in the case.

When the foil bearing further includes a top foil having a bearing surface, the foil may be a back foil that supports the top foil from behind.

As described above, according to the foil bearing according to the present invention, the foil and the foil holder can be engaged in the axial direction without increasing the cost due to the increase in the number of parts and man-hours or complicating the design of the foil. , It is possible to prevent the positional deviation between the two in the axial direction.

It is a front view of the foil bearing which concerns on 1st embodiment of this invention. It is a top view of foil. It is a perspective view of the foil bearing of FIG. FIG. 4 is an enlarged view of FIG. 3. It is a perspective view of the temporary assembly of foil. It is a perspective view which shows a mode that the temporary assembly of foil is inserted in the inner periphery of a foil holder. It is an enlarged plan view of the foil which concerns on 2nd embodiment of this invention. It is a top view of the foil which concerns on 3rd embodiment of this invention. FIG. 9 is a perspective view of a foil bearing having the foil of FIG. 8. It is a perspective view of the foil bearing which concerns on 4th embodiment of this invention. It is sectional drawing of the foil bearing of FIG. It is a perspective view of the foil bearing which concerns on 5th embodiment of this invention. It is a front view of the foil bearing of FIG. It is a top view of the foil of the foil bearing which concerns on 6th embodiment of this invention. It is a perspective view of the foil holder of the foil bearing which concerns on 6th embodiment. It is a cross-sectional perspective view of the foil holder of FIG. It is a perspective view of the temporary assembly using the foil of FIG. It is a perspective view which shows a mode that the temporary assembly of the foil of FIG. 17 is inserted in the inner periphery of the foil holder of FIG. It is a section perspective view of the foil bearing concerning a 6th embodiment. It is sectional drawing of the foil bearing which concerns on 6th embodiment. It is sectional drawing which shows the other example of the foil bearing which concerns on 6th embodiment. It is a perspective view which shows the foil of the conventional foil bearing.

Hereinafter, an embodiment of a foil bearing according to the present invention will be described with reference to the drawings.

FIG. 1 shows a foil bearing 10 according to a first embodiment of the present invention. The foil bearing 10 supports the shaft 2 inserted in the inner periphery in the radial direction. The foil bearing 10 is an air dynamic pressure bearing that uses air as a pressure generating fluid. The foil bearing 10 includes a foil holder 11 and one or more foils 12 attached to the inner peripheral surface 11 a of the foil holder 11. The foil bearing 10 in the illustrated example has three foils 12. Hereinafter, in the description of each foil 12, the downstream side in the fluid flow direction with respect to the foil 12 when the shaft 2 is relatively rotated is referred to as “downstream side”, and the opposite side is referred to as “upstream side”. The three foils 12 have the same shape, but for ease of understanding, the foils 12 are shaded (or hatched density difference) in the drawing.

The foil holder 11 is formed in a cylindrical shape with metal or resin. In the present embodiment, the inner peripheral surface 11a of the foil holder 11 is a cylindrical surface having a uniform diameter in the entire axial direction. The outer peripheral surface 11b of the foil holder 11 is fixed to a housing of a facility (for example, a turbo machine such as a gas turbine) in which the foil bearing 10 is incorporated. Grooves 11c into which the end portions of the foils 12 are inserted are formed at a plurality of locations (three locations in the illustrated example) spaced apart in the circumferential direction on the inner peripheral surface 11a of the foil holder 11. The groove 11 c extends in the axial direction, and both ends in the axial direction are open to both end surfaces 11 d of the foil holder 11. In addition, you may provide the groove | channel 11c in the axial direction partial area | region of the internal peripheral surface 11a of the foil holder 11, or may be provided in the direction inclined with respect to the axial direction.

The foil 12 is formed of a metal having a high spring property and good workability, for example, steel or copper alloy. The foil 12 is formed by pressing or electric discharge machining a metal foil having a thickness of about 20 μm to 200 μm. In the air dynamic pressure bearing using air as the pressure generating fluid as in the present embodiment, since there is no lubricating oil in the atmosphere, the foil 12 is preferably formed of stainless steel or bronze.

As shown in FIG. 2, the foil 12 includes a main body part M, and connection parts 12 e and locking parts 12 f provided on both axial sides of the main body part M. In a state before being attached to the foil holder 11, the foil 12 is provided on the same plane. As shown in FIG. 3, in the state where the foil 12 is attached to the inner peripheral surface 11a of the foil holder 11, the main body portion M of the foil 12 is provided in the axial region of the foil holder 11, and the connection portion 12e of the foil 12 and the engagement portion are connected. The stop portion 12f protrudes to both sides in the axial direction of the inner peripheral surface 11a of the foil holder 11. When attached to the foil holder 11, the entire area of the foil 12 is parallel to the axial direction.

As shown in FIG. 2, the body portion M of the foil 12 includes a top foil portion 12a, an insertion portion 12b provided on the downstream side (upper side in FIG. 2) of the top foil portion 12a, and an upstream side of the top foil portion 12a. And an underfoil portion 12c provided on the side (the lower side in FIG. 2).

The surface on the inner diameter side of the top foil portion 12a functions as a bearing surface facing the outer peripheral surface 2a of the shaft 2 (see FIG. 1). In the present embodiment, only the top foil portion 12a of the body portion M of each foil 12 is exposed on the inner peripheral side, and the insertion portion 12b and the underfoil portion 12c are behind the other foils 12 (outer diameter side). Arranged.

The insertion part 12b extends downstream from the top foil part 12a. The insertion part 12b and the top foil part 12a are smoothly continuous in the circumferential direction. In the present embodiment, as shown in FIG. 2, the insertion portions 12b are provided at a plurality of locations (three locations in the illustrated example) spaced apart in the axial direction. A recess 12d is provided between the plurality of insertion portions 12b in the axial direction. An axial cut 12d1 is provided at the corner of the recess 12d. Note that the cut 12d1 may be omitted unless particularly required.

The underfoil portion 12c extends upstream from the top foil portion 12a. The underfoil portion 12c and the top foil portion 12a are smoothly continuous in the circumferential direction. In the present embodiment, the underfoil portions 12c are provided at a plurality of locations (two locations in the illustrated example) separated in the axial direction. Each underfoil portion 12c is provided in the same axial region as the recess 12d (including the cut 12d1). Concave portions 12c1 are provided between the axial directions of the plurality of underfoil portions 12c and on the axially outer side.

As shown in FIG. 1, the underfoil portion 12 c of each foil 12 is disposed between the top foil portion 12 a of the foil 12 adjacent to the upstream side and the inner peripheral surface 11 a of the foil holder 11. Thereby, the top foil part 12a of each foil 12 is supported from the back by the underfoil part 12c of the foil 12 adjacent to the downstream. Further, edges (concave portions 12d and concave portions 12c1) of the end portions in the circumferential direction of the top foil portions 12a of the adjacent foils 12 are engaged with each other in the circumferential direction and stick to each other. Thereby, the top foil part 12a of each foil 12 protrudes to the outer diameter side, and is curved into a substantially cylindrical shape along the inner peripheral surface 11a of the foil holder 11.

As shown in FIG. 2, the foil 12 includes a connecting portion 12e smoothly connected to the main body M in the axial direction, and a locking portion 12f smoothly connected to the connecting portion 12e in the circumferential direction. The connection portion 12e and the locking portion 12f are provided in an axial region different from the main body portion M, and in the illustrated example, are provided on the outer side in the axial direction of the main body portion M, particularly on both sides in the axial direction of the main body portion M. The connecting portion 12e is continuous in the axial direction with, for example, a region including the downstream end portion of the main body M, specifically, the insertion portion 12b and the downstream region of the top foil portion 12a continuous on the upstream side. is doing. In FIG. 2, a conceptual boundary between the main body M and the connecting part 12e is indicated by a dotted line.

The locking portion 12f is connected to the main body portion M through the connection portion 12e, and is separated from the main body portion M in the axial direction. In the illustrated example, a circumferential slit 12g is provided between the locking portion 12f and the main body M in the axial direction to divide them in the axial direction. The locking portion 12f in the illustrated example extends upstream from the connection portion 12e, and its upstream end is a free end. The entire locking portion 12f in the illustrated example is provided in the circumferential region of the top foil portion 12a.

In addition, the intensity | strength of the latching | locking part 12f can be adjusted by changing the axial direction dimension and circumferential direction dimension of the latching | locking part 12f. Increasing the axial dimension of the locking part 12f improves the strength of the locking part 12f, but increases the axial dimension of the foil 12 as a whole. Further, when the circumferential dimension of the locking portion 12f is reduced, the strength (rigidity) of the locking portion 12f is improved, but the engagement area with the foil holder 11 is reduced. The dimensions of each part may be set in consideration of these.

As shown in FIG. 1, the top foil portion 12 a and the under foil portion 12 c of the foil 12 are curved in a substantially cylindrical shape along the inner peripheral surface 11 a of the foil holder 11. Further, as shown in FIG. 4, the connecting portion 12e of the foil 12 is continuous with the main body portion M (top foil portion 12a) in the axial direction. Yes.

On the other hand, since the locking portion 12f of the foil 12 is separated from the main body portion M in the axial direction, it does not deform following the main body portion M. Moreover, since the latching | locking part 12f is provided in the axial direction outer side rather than the internal peripheral surface 11a of the foil holder 11, it is not restrained by the foil holder 11 from an outer-diameter side. Accordingly, the locking portion 12f is not restricted by the main body portion M or the foil holder 11, and can be independently deformed. In the present embodiment, due to the elastic restoring force of the foil 12, the locking portion 12f has a flat plate shape that is smoothly continuous with the connecting portion 12e in the circumferential direction, and more specifically, the connection at the boundary between the connecting portion 12e and the locking portion 12f. It becomes flat form extended in the substantially tangential direction of the part 12e. As a result, the engaging portion 12f is displaced to the outer diameter side with respect to the inner peripheral surface 11a of the foil holder 11 as it goes upstream, and as a result, the engaging portion 12f is displaced from the inner peripheral surface 11a of the foil holder 11. Is also arranged on the outer diameter side (see FIGS. 1 and 4). As a result, the engaging portion 12f of the foil 12 and the end surface 11d of the foil holder 11 can be engaged in the axial direction, so that the foil 12 can be provided without providing a separate engaging member or bending the foil 12. And the axial displacement of the foil holder 11 can be prevented.

In the present embodiment, the rear locking portion 12f that is not visible in FIGS. 3 and 4 also has the same configuration as described above, and can be engaged with the rear end surface of the foil holder 11 in the axial direction. . That is, the foil holder 11 is arranged between the pair of locking portions 12f provided at both ends of the foil 12 in the axial direction, and the foil holder 11 is sandwiched by both locking portions 12f from both sides in the axial direction. Thereby, since both the latching | locking parts 12f can engage with the foil holder 11 from an axial direction both sides, the movement to the axial direction both sides with respect to the foil holder 11 of the foil 12 can be controlled.

Hereinafter, a method for assembling the foil bearing 10 will be described.

First, as shown in FIG. 5, a cylindrical temporary assembly X is formed by combining three flat foils 12. Specifically, the underfoil portion 12c and the insertion portion 12b of the adjacent foil 12 are fitted together. That is, the underfoil portion 12 c of each foil 12 is inserted into the recess 12 d on the downstream side of the adjacent foil 12, and the insertion portion 12 b of each foil 12 is inserted into the recess 12 c 1 on the upstream side of the adjacent foil 12. Thereby, the three foils 12 are connected, and the temporary assembly X is formed.

Next, as shown in FIG. 6, the temporary assembly X is inserted into the inner periphery of the foil holder 11 in a state of being rounded into a cylindrical shape. At this time, the locking portion 12f of each foil 12 does not deform following the main body portion M, and thus jumps out to the outer diameter side. Accordingly, the locking portion 12f (not visible in FIG. 6) on one axial side (the insertion direction leading side) of each foil 12 is elastically deformed to the inner diameter side with respect to the inner peripheral surface 11a of the foil holder 11 so that the foil is The temporary assembly X is inserted into the inner periphery of the foil holder 11 while avoiding interference with the holder 11. On the other hand, since the engaging portion 12f on the other axial side of each foil 12 is not inserted into the inner periphery of the foil holder 11, it is left protruding to the outer diameter side. In this state, the temporary assembly X is inserted into the inner periphery of the foil holder 11 while inserting the insertion portion 12b of each foil 12 into the groove 11c opened from the end surface of the foil holder 11 from the outside in the axial direction.

And if the latching | locking part 12f of the axial direction one side of each foil 12 passes the inner peripheral surface 11a of the foil holder 11, and will come out to an axial direction outer side, the locking part 12f of the axial direction one side will be elastically flat. It restores and is arranged on the outer diameter side from the inner peripheral surface 11a of the foil holder 11. On the other hand, the locking portion 12f on the other axial side of each foil 12 is arranged in the immediate vicinity of the other end surface 11d in the axial direction of the foil holder 11 while being arranged on the outer diameter side of the inner peripheral surface 11a of the foil holder 11. Is done. As described above, the foil holder 11 is disposed between the axial directions of the pair of locking portions 12f provided on both axial sides of each foil 12. In addition, each latching | locking part 12f and the end surface 11d of the foil holder 11 may be contact | abutted, and may be made to oppose via a micro axial direction clearance gap.

Thus, in this embodiment, the foil 12 is provided with a locking portion 12f that is separated from the main body portion M in the axial direction and can be deformed in the radial direction independently of the main body portion M. The foil holder 11 protrudes outward in the axial direction from the inner peripheral surface 11 a and is arranged at a position where the foil holder 11 is not restrained from the outer diameter side. Thereby, only by attaching the foil 12 to the inner peripheral surface 11a of the foil holder 11, the engaging portion 12f is arranged on the outer diameter side of the inner peripheral surface 11a of the foil holder 11 by the elastic restoring force of the engaging portion 12f. Can do.

When the shaft 2 rotates in the direction of the arrow in FIG. 1, a bearing gap R is formed between the inner diameter surface (bearing surface) of the top foil portion 12 a of each foil 12 of the foil bearing 10 and the outer peripheral surface 2 a of the shaft 2. At this time, the top foil part 12a of each foil 12 rides on the underfoil part 12c of the foil 12 adjacent to the downstream side. Moreover, the insertion part 12b provided in the downstream edge part of each foil 12 is inserted in the groove | channel 11c of the foil holder 11, Thereby, the downstream end vicinity of the top foil part 12a is the curve direction of the top foil part 12a whole. It tends to bend in a direction opposite to the bending direction of the inner peripheral surface 11a of the foil holder 11, that is, convex toward the inner diameter side. As described above, the wedge-shaped bearing gap R having the gap width gradually narrowed toward the downstream side is formed, and air is pushed into the narrow side of the wedge-shaped bearing gap R, so that the air film of the bearing gap R is reduced. The pressure is increased, and the shaft 2 is supported in a non-contact manner in the radial direction by this pressure. In FIG. 1, the width of the bearing gap R is exaggerated.

As described above, the top foil portion 12a of each foil 12 rides on the underfoil portion 12c of the other foil 12, and the vicinity of the downstream end of the top foil portion 12a is curved so as to protrude toward the inner diameter side. A spring property in the radial direction is imparted to the top foil portion 12a. As a result, the bearing surface of the top foil portion 12a of each foil 12 is arbitrarily deformed according to the operating conditions such as the load, the rotational speed of the shaft 2, the ambient temperature, etc., so the bearing gap R has an appropriate width according to the operating conditions. Automatically adjusted. Therefore, the bearing gap can be managed to the optimum width even under severe conditions such as high temperature and high speed rotation, and the shaft 2 can be stably supported.

Further, each foil 12 is not completely fixed to the foil holder 11 and can be moved minutely with respect to the foil holder 11. Therefore, while the shaft 2 is rotating, the foil 12 is pressed against the foil holder 11 due to the influence of the air film formed in the bearing gap, and accordingly, the foil 12 and the foil holder 11, particularly the underfoil of each foil 12, are pressed. Minute sliding occurs between the outer diameter surface of the portion 12 c and the inner peripheral surface 11 a of the foil holder 11, or between the insertion portion 12 b of each foil 12 and the groove 11 c of the foil holder 11. The vibration of the shaft 2 can be attenuated by the frictional energy generated by the minute sliding.

Note that the bearing surface of each foil 12 and the outer peripheral surface of the shaft 2 slide in contact with each other at the time of low-speed rotation immediately before the shaft 2 stops or immediately after the shaft 2 starts. At this time, if a coating made of PTFE, DLC, titanium aluminum nitride, or the like is provided on the bearing surface of each foil 12, the bearing surface can be prevented from being worn. Moreover, in order to adjust the frictional force caused by the minute sliding between the foil 12 and the foil holder 11, the above-described coating may be formed on one or both of them. In addition to the above, a tungsten disulfide film or a molybdenum disulfide film may be used as a film provided on the foil 12 or the foil holder 11.

The present invention is not limited to the above embodiment. Hereinafter, although other embodiment of this invention is described, description which abbreviate | omits the said embodiment is abbreviate | omitted.

In the second embodiment shown in FIG. 7, a region 12g1 having a wide axial width is provided at the downstream end of the slit 12g. In this case, stress concentration at the downstream end of the slit 12g is alleviated, and damage to the foil 12 can be prevented.

8 differs from the above embodiment in that the locking portion 12f of each foil 12 extends downstream from the connecting portion 12e, and the downstream end is a free end. The locking portion 12f is provided on the downstream side of the main body portion M. Specifically, a connecting portion 12e is provided continuously outside the insertion portion 12b of each foil 12 in the axial direction, and a locking portion 12f extends continuously downstream of the connecting portion 12e. When the foil 12 is attached to the inner peripheral surface 11a of the foil holder 11, as shown in FIG. 9, the locking portion 12f extends on the extension line of the connecting portion 12e, and the outer diameter is larger than the inner peripheral surface 11a of the foil holder 11. Arranged on the side.

In the above embodiment, the connection part 12e is connected to the downstream end of the main body part M of each foil 12, but the connection part is not limited to this, and is connected to the upstream end part or the circumferential intermediate part of the main body part M. 12e may be connected.

Further, in the fourth embodiment shown in FIG. 10, a recess 11 e is provided at the axial end of the inner peripheral surface 11 a of the foil holder 11. The recess 11e in the illustrated example is continuously provided on the entire circumference. The axial dimension of the recess 11e is slightly larger than the axial dimension of the connection part 12e and the locking part 12f of the foil 12. The connecting portion 12e and the locking portion 12f of the foil 12 are accommodated in the axial direction region of the recess 11e (see FIG. 11). Thereby, since the connection part 12e and the latching | locking part 12f of the foil 12 do not protrude to the axial direction outer side from the foil holder 11, when incorporating the foil bearing 10 in a turbomachine etc., the connection part 12e and the latching | locking part 12f of the foil 12 Can be prevented from being damaged by contact with the housing of the turbomachine. The locking portion 12f of the foil 12 can be engaged with an end surface 11e1 (shoulder surface) formed in the concave portion 11e of the foil holder 11 in the axial direction.

The recess 11e on the inner peripheral surface of the foil holder 11 is not necessarily formed on the entire periphery. For example, as in the fifth embodiment shown in FIGS. 12 and 13, the recesses 11e may be provided at a plurality of locations separated in the circumferential direction. The locking portion 12f of each foil 12 is accommodated in the axial region of each recess 11e. In addition, in said 4th and 5th embodiment, the latching | locking part 12f of the foil 12 may be separated from the bottom face (surface parallel to an axial direction) of the recessed part 11e of the foil holder 11, and may be extended in flat form. The locking portion 12f may be curved toward the inner diameter side by contacting the bottom surface of the recess 11e.

In the above embodiment, the case where the locking portions 12f and the connection portions 12e are provided on both sides in the axial direction of the main body portion M of the foil 12 has been described. If there is no particular need, any of the locking portions 12f and the connection portions 12e. May be omitted, and the locking portion 12f and the connecting portion 12e may be provided only on one side in the axial direction of the body portion M of the foil 12.

In the sixth embodiment shown in FIG. 14, the connecting portion 12e and the locking portion 12f of the foil 12 are provided in the axially intermediate portion of the foil 12 (in the illustrated example, the axially central portion). Different from form. Specifically, the main body portions M are continuously provided on both sides in the axial direction of the connecting portion 12e. In the example of illustration, the connection part 12e is following the area | region including the downstream end part of the top foil part 12a of each main-body part M, especially the top foil part 12a in the axial direction. The locking portion 12f extends upstream from the connection portion 12e. Between the latching | locking part 12f and each main-body part M, the slit 12g is each provided.

The foil 12 is attached to the foil holder 11 shown in FIG. A concave portion is provided in the axially intermediate portion of the inner peripheral surface 11 a of the foil holder 11. In the present embodiment, as shown in the cross-sectional view of FIG. 16, the concave portion is formed on the inner peripheral surface 11 a and the outer peripheral surface 11 b of the foil holder 11 as a concave portion in the axial direction intermediate portion (axial central portion in the illustrated example). An open through-hole 11f is provided. The same number of through holes 11f as the locking portions 12f of the foil 12 are provided, and in the illustrated example, the through holes 11f are provided at three locations at equal intervals in the circumferential direction. Side walls 11f1 on both sides in the circumferential direction of each through hole 11f are concave curved surfaces parallel to the axial direction. In the illustrated example, side walls 11f1 on both sides in the circumferential direction of each through hole 11f are provided on the same cylindrical surface.

The foil bearing 10 of the present embodiment is assembled in the same procedure as that of the first embodiment. Specifically, first, as shown in FIG. 17, the underfoil portion 12c and the insertion portion 12b of the three foils 12 are fitted together to form a cylindrical temporary assembly X.

Next, as shown in FIG. 18, the temporary assembly X is inserted into the inner circumference of the foil holder 11 in a state of being rounded into a cylindrical shape. At this time, the temporary assembly X is removed from the foil holder 11 while elastically deforming the locking portion 12f that protrudes from the cylindrical assembly X to the outer diameter side toward the inner diameter side of the inner peripheral surface 11a of the foil holder 11. 11 is inserted into the inner periphery. Then, when the locking portion 12f is fitted into the through hole 11f in the central portion in the axial direction of the foil holder 11, the locking portion 12f is elastically restored to a flat plate shape as shown in FIGS. 19 and 20, and the foil holder 11 is arranged closer to the outer diameter side than the inner peripheral surface 11a. Thus, the engaging portion 12f of the foil 12 is accommodated in the through hole 11f of the foil holder 11, and the side walls 11f2 on both sides in the axial direction of the through hole 11f (in FIGS. 19 and 20, only one side wall 11f2 in the axial direction is shown). The locking portion 12f is disposed between the axial directions. As a result, the locking portion 12f can be engaged with the side walls 11f2 on both axial sides of the through hole 11f, and the foil 12 is prevented from coming off from the foil holder 11 in the axial direction.

When the shaft 2 rotates in the direction of arrow P in FIG. 20, a bearing gap R is formed between the inner diameter surface (bearing surface) of the top foil portion 12 a of each foil 12 of the foil bearing 10 and the outer peripheral surface 2 a of the shaft 2. . At this time, by providing the main body part M on both axial sides of the connecting part 12e, the bearing surface (top foil part 12a) is formed at two locations separated in the axial direction. Thus, the moment rigidity of the foil bearing 10 increases because the bearing surfaces are clearly doubled.

Further, as the fluid (air) in the bearing gap R flows in the rotation direction of the shaft 2, as shown by the arrow Q direction in FIG. In particular, it flows into the bearing gap R. As a result, the amount of air in the bearing gap R increases and the pressure of the air film in the bearing gap R is further increased, so that the load capacity of the foil bearing 10 is increased. Further, the outside air flows into the bearing gap R, so that the bearing surface (top foil portion 12a) can be cooled. In particular, in FIG. 20, the side walls 11f1 on both sides in the circumferential direction of the through hole 11f of the foil holder 11 are concave curved surfaces parallel to the axial direction. As a result, for example, as shown in FIG. 21, compared with the case where the side walls 11f1 on both sides in the circumferential direction of the through-hole 11f of the foil holder 11 are flat surfaces, the external air is passed through the through-hole 11f when the shaft 2 is rotated. Since it tends to flow into the bearing gap R, it is easy to improve the bearing rigidity and cool the bearing surface. In addition, if the communication path (through-hole etc.) which connects said through-hole 11f and the exterior is provided in the housing to which the outer peripheral surface of the foil holder 11 is attached, external air will more easily flow into the bearing gap R. .

In addition, the circumferential position, the axial position, and the number of the locking portion 12f and the through hole 11f are not limited to the above, and may be increased or decreased.

The foil bearing to which the present invention is applied is not limited to the above. For example, the present invention may be applied to a bump-type foil bearing having a top foil having a bearing surface and a back foil that elastically supports the top foil from behind. In this case, the foil having the locking portion and the connecting portion, which is a characteristic configuration of the present invention, may be a top foil or a back foil.

In the above embodiment, the case where the foil bearing 10 is fixed and the shaft 2 is rotated is shown. However, the present invention is not limited to this, and the foil bearing 10 may be rotated while the shaft 2 is fixed. However, if the foil bearing 10 is rotated, the foil 12 may be damaged by centrifugal force. Therefore, the foil bearing 10 is preferably fixed.

The foil bearing 10 shown above can be used as a bearing for a vehicle such as an automobile or a bearing for industrial equipment, in addition to a turbo machine such as a gas turbine or a turbocharger (supercharger). .

Further, 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.

2 shaft 10 foil bearing 11 foil holder 11e recess 11f through hole (recess)
12 Foil 12a Top foil part

12b Insertion part

12c Underfoil part

12e Connection part 12f Locking part M Body part R Bearing gap X Temporary assembly

Claims

A foil bearing comprising a tubular foil holder and a foil attached to the inner peripheral surface of the foil holder, and supporting a shaft inserted in the inner periphery so as to be relatively rotatable,
The foil is continuous along the inner peripheral surface of the foil holder, the main body portion is continuous with the main body portion in the axial direction, and the connection portion is curved similarly to the main body portion, and is continuous with the connection portion in the circumferential direction. And the foil bearing provided with the latching | locking part which was distribute | arranged to the outer diameter side rather than the internal peripheral surface of the said foil holder, and can be engaged with the said foil holder in an axial direction.
The foil bearing according to claim 1, wherein the locking portion is smoothly continuous with the connecting portion.
The foil bearing according to claim 1 or 2, wherein the locking portions are provided at both axial ends of the foil, and the foil holder is disposed between the axial directions of both locking portions.
The foil bearing according to any one of claims 1 to 3, wherein a concave portion is provided at an axial end portion of the inner peripheral surface of the foil holder, and a locking portion of the foil is accommodated in an axial region of the concave portion.
The foil bearing according to claim 1 or 2, wherein a concave portion is provided in an axially intermediate portion of the inner peripheral surface of the foil holder, and a locking portion of the foil is arranged between side walls on both axial sides of the concave portion.
The foil bearing according to claim 5, wherein the concave portion is configured by a radial through hole.
The foil bearing according to claim 6, wherein side walls on both sides in the circumferential direction of the through hole are concave curved surfaces parallel to the axial direction.
The foil bearing according to any one of claims 1 to 7, wherein a bearing surface facing the outer peripheral surface of the shaft is provided on the main body portion of the foil.
The foil bearing according to claim 8, wherein the main body portion of the foil is provided on both axial sides of the connection portion.
The foil bearing according to any one of claims 1 to 7, further comprising a top foil having a bearing surface, wherein the foil is a back foil that supports the top foil from behind.
A foil that is attached to the inner peripheral surface of the tubular foil holder and constitutes a foil bearing,
A main body that is curved along an inner peripheral surface of the foil holder, a connecting portion that is continuous in the axial direction of the main body and the foil holder, and is curved in the same manner as the main body, and the connecting portion and the foil holder. A foil comprising a locking portion that is continuous in the circumferential direction, is disposed on the outer diameter side of the inner circumferential surface of the foil holder, and is engageable with the foil holder in the axial direction.