JP2016148368A - Thrust bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thrust bearing capable of resisting a high load by suppressing the contact of a top foil piece with a thrust collar.SOLUTION: A thrust bearing is equipped with a top foil; a back foil supporting the top foil; and a base plate supporting the back foil. The back foil is formed by a plurality of back foil pieces, and the top foil is formed by a plurality of top foil pieces arranged on the back foil pieces. The top foil piece is formed with a fixing portion fixed to the base plate, on a rotating direction upstream side of a rotary shaft, and by thinning a surface opposite to the back foil piece, on an inner peripheral end side and an outer peripheral end side, an inner peripheral end side thin wall portion and an outer peripheral end side thin wall portion formed to be thinner than an intermediate area between the inner peripheral end side and the outer peripheral end side are formed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a thrust bearing.

  Conventionally, as a bearing for a high-speed rotating body, a thrust bearing is known that is disposed to face a thrust collar provided on a rotating shaft. As such a thrust bearing, a foil-type thrust bearing, that is, a thrust foil bearing is well known. Thrust foil bearings are made of a flexible foil (thin metal plate) with a bearing surface that can absorb the movement of the rotating shaft (axial displacement and inclination of the thrust collar) caused by vibration and impact. A foil structure for flexibly supporting the bearing surface.

  As one form of such a thrust foil bearing, a bearing surface is formed by a plurality of annular (annular) foil pieces (top foil pieces) obtained by dividing an annular plate in the circumferential direction, and these top surfaces are formed. A structure is known in which each foil piece is supported by a corrugated foil piece (bump foil piece) (see, for example, Patent Document 1). Each top foil piece (having a thickness of about 100 μm) has an inclination angle with respect to the thrust collar, whereby a bearing gap between the thrust collar and the top foil piece is formed in a wedge shape in a side view. That is, the bearing gap is narrowed from the upstream side in the rotational direction of the thrust collar (rotating shaft) toward the downstream side. Therefore, when the thrust collar rotates from the side having the large bearing gap (upstream side) toward the side having the narrow bearing gap (downstream side), the lubricating fluid flows into the wedge and the load capacity is exhibited.

  The top foil piece is fixed to the base plate only at the upstream end of the thrust collar (rotating shaft) in the rotation direction. When the bearing load increases, the top foil is supported by the fixed side (upstream end) as a fulcrum. The maximum load capacity is generated when the inclination is relaxed to become horizontal and the inclination angle becomes about 0.1 °. On the other hand, the bump foil piece is arranged so that the ridge of the mountain is parallel to the downstream edge of the top foil piece, and only the edge of the bump foil piece on the downstream side in the rotation direction of the thrust collar (rotating shaft) is the base plate. It is fixed. That is, the upstream side edge is a free end.

  The bump foil pieces are arranged and fixed in this way because the pressure of the fluid lubricating film generated on the top foil pieces becomes higher on the narrow side (downstream side) of the bearing gap, and this part has high rigidity. This is because the load capacity is increased by supporting the above.

JP-A-10-331847

  By the way, in the thrust foil bearing structure described above, the bearing gap is narrowest on the downstream side end side of the top foil, and may reach submicron when the load is high. Therefore, contact with the thrust collar is likely to occur on the downstream end side. When contact occurs, the bearing life is reduced, and in the worst case, seizure occurs. In order to avoid this, it is desirable to always keep the downstream edge of the top foil and the thrust collar parallel.

  However, in general, in the thrust foil bearing, the circumferential speed of the thrust collar on the outer peripheral end side is higher than the peripheral speed on the inner peripheral end side, so that the pressure (film pressure) of the fluid lubricating film increases on the outer peripheral end side. The pressure (membrane pressure) is low because the peripheral speed is slow on the inner peripheral end side. For this reason, although the outer peripheral end side of the top foil is pushed toward the bump foil side and moves away from the thrust collar, the inner peripheral end side rises to the thrust collar side and approaches the thrust collar. As a result, on the downstream side edge side of the top foil, the thickness of the fluid lubricating film on the inner peripheral edge side becomes extremely thin and cannot withstand a high load.

  Therefore, in the conventional thrust bearing, for example, as shown in Patent Document 1, the bump foil is divided into a plurality of pieces in the radial direction. In the bump foil divided in this way, (a) a bump foil having low rigidity is arranged on the inner peripheral side, or (b) the height of the bump foil peak on the inner peripheral side is reduced, so that the top foil is reduced. It is considered that the supporting force on the inner peripheral side is weakened to suppress the rising on the inner peripheral end side.

  However, even when trying to manufacture a thrust bearing by dividing and adjusting the bump foil in this way, for example, in (a), it is difficult to appropriately control the rigidity on the inner and outer peripheral sides of the bump foil, Therefore, it is difficult to design the bump foil. Further, in (b), since it is necessary to control the height of the bump foil crest at a level of 10 μm, it is difficult to manufacture, and it is particularly difficult to ensure quality during mass production.

  Further, as described above, generally, the outer peripheral end side on the downstream side edge side of the top foil is pushed into the bump foil side and away from the thrust collar due to the difference in peripheral speed compared to the inner peripheral end side. Move. However, on the outer peripheral side of the top foil, the pressure of the fluid lubricating film is the same as the ambient pressure (for example, atmospheric pressure) at the outer peripheral end, so the film pressure of the fluid lubricating film at the outer peripheral end is It becomes low compared with the side (the place that entered inward from the outer peripheral edge). For this reason, the top foil rises not only at the inner peripheral end but also at the outer peripheral end, and the outer peripheral end may be locally worn.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thrust bearing capable of withstanding a high load by suppressing the top foil from contacting the thrust collar. .

  A thrust bearing according to the present invention is a thrust bearing disposed to face a thrust collar provided on a rotating shaft, and includes a top foil disposed to face the thrust collar, and the thrust collar of the top foil. The back foil is disposed opposite to the surface opposite to the surface opposite to the back foil and supports the top foil, and the back foil is disposed on the opposite side of the top foil to support the back foil. The back foil is formed by a plurality of back foil pieces arranged in the circumferential direction of the base plate, and the top foil is disposed on each of the back foil pieces. Formed on the top foil piece in the rotational direction of the rotating shaft. On the side, a fixed portion fixed to the base plate is formed, and the surface facing the back foil piece is thinned, so that the inner peripheral end side and the outer peripheral end side are arranged on the inner peripheral end side. An inner peripheral end side thin portion and an outer peripheral end side thin portion formed thinner than an intermediate region between the outer peripheral end side and the outer peripheral end side are formed.

According to this thrust bearing, since the surface facing the back foil piece is thinned, the inner peripheral end side formed thinner than the intermediate region on the inner peripheral end side and the outer peripheral end side of the top foil piece. Since the thin portion and the outer peripheral end side thin portion are formed, the inner peripheral end side and the outer peripheral end side are more easily bent than the intermediate region.
Further, since a gap is formed between the inner peripheral end side and the back foil piece by the inner peripheral end side thin portion, the inner peripheral end side is easily pushed into the back foil piece side. At that time, a force to push back the top foil piece back to the thrust collar side by the back foil piece due to the gap is less likely to be generated on the inner peripheral end side. Therefore, it is possible to prevent the inner peripheral end side from easily rising to the thrust collar side due to the lower peripheral speed of the thrust collar on the inner peripheral end side of the thrust bearing than the peripheral speed on the outer peripheral end side. The foil pieces are prevented from approaching and contacting the thrust collar.
Moreover, since a gap is formed between the outer peripheral end side and the back foil piece by the outer peripheral end side thin portion, the outer peripheral end side is easily pushed into the back foil piece side. At that time, it is difficult for the back foil piece to push back the top foil piece back to the thrust collar side due to the gap on the outer peripheral end side. Therefore, the pressure of the fluid lubrication film at the outer peripheral end of the top foil becomes the same as the ambient pressure (for example, atmospheric pressure), so that the outer peripheral end side is prevented from easily rising to the thrust collar side, and the top foil piece becomes the thrust collar. Is prevented from coming into contact with this.

Further, in the thrust bearing, it is preferable that the inner peripheral end side thin portion is wider in the radial direction than the outer peripheral end side thin portion.
Due to the fact that the peripheral speed of the thrust collar on the inner peripheral end side of the thrust bearing is slower than the peripheral speed on the outer peripheral end side, the portion on the inner peripheral end side of the top foil that easily rises to the thrust collar side is The pressure of the fluid lubricant film at the outer peripheral end is wider than the portion on the outer peripheral end side of the top foil that easily rises to the thrust collar side due to the same pressure as the ambient pressure (for example, atmospheric pressure). Therefore, by making the inner peripheral end side thin portion wider in the radial direction than the outer peripheral end side thin portion, it is more effectively prevented that the top foil piece approaches the thrust collar and comes into contact therewith.

In the thrust bearing, it is preferable that the inner peripheral end side thin portion is thinner than the outer peripheral end side thin portion.
As described above, the portion that is likely to rise to the thrust collar side is wider on the inner peripheral end side than on the outer peripheral end side. Therefore, by making the inner peripheral end side thin part thinner than the outer peripheral end side thin part, the gap between the inner peripheral end side thin part and the back foil piece becomes the outer peripheral end side thin part. Since it becomes larger than the gap, it is more effectively prevented that the top foil piece approaches and contacts the thrust collar.

In the thrust bearing, it is preferable that the back foil piece is divided into a plurality of parts in the radial direction in the circumferential direction and a continuous side in which the other side is continuous in the radial direction.
According to this thrust bearing, one side in the circumferential direction of the back foil piece is divided into a plurality of pieces in the radial direction, so that the divided piece on the inner peripheral side and the divided piece on the outer peripheral side are independent from each other. Accordingly, the deformation of the back foil piece that occurs when the top foil piece is pushed into the back foil piece side becomes smooth in the radial direction. Therefore, the support force by the back foil piece also changes more smoothly in the radial direction. In addition, since the divided pieces of the back foil piece are integrated by the continuous sides, the back foil piece can be easily fixed on the base plate.

Further, in the thrust bearing, the fixed portion side thin portion formed thinner than the intermediate region on the fixed portion of the top foil and in the vicinity of the fixed portion on the downstream side in the rotation direction of the rotating shaft from the fixed portion. Is preferably formed.
In this way, the rotation direction downstream side of the rotation axis of the top foil piece can be inclined easily and smoothly. Therefore, for example, when the thrust collar is sandwiched between the pair of top foils, the starting torque Is reduced. Further, even after the rotation shaft starts rotating, the top foil piece easily and smoothly inclines, so that the optimum inclination angle can be easily obtained and the load capacity is improved.

Further, in the thrust bearing, the top foil piece is formed in an arc plate shape obtained by dividing an annular plate in the circumferential direction, and a boundary line between the inner peripheral end side thin portion and the intermediate region is The top foil piece has an arc shape along the circumferential direction of the inner peripheral end, and the boundary line between the outer peripheral end side thin portion and the intermediate region is an arc shape along the circumferential direction of the outer peripheral end of the top foil piece. It is preferable that
In this way, it is possible to suppress that the inner peripheral end side and the outer peripheral end side of the top foil piece easily rise to the thrust collar side from the upstream side to the downstream side in the rotational direction of the rotating shaft, and therefore the top foil piece is suppressed. Is more reliably prevented from approaching and contacting the thrust collar.

Further, in the thrust bearing, the fixed portion of the top foil is formed including a linear fixed side located on the upstream side in the rotation direction of the rotating shaft, and the back foil piece includes a peak portion and a valley portion. Are formed by corrugated bump foil pieces that are alternately formed, and the arrangement direction of the peaks is arranged so as to intersect with the fixed sides, and the top foil piece is opposed to the bump foil pieces. It is preferable that a valley-side thin part formed thinner than a part facing the peak part is formed at a part facing the valley part because a part of the part is thinned.
When the pressure of the fluid lubrication film acts on the top foil piece, the deflection toward the back foil side increases at the radial center between the inner and outer peripheral ends of the top foil piece. The load capacity decreases as the pressure decreases.
Therefore, by forming the valley-side thin portion, the top foil piece tends to bend from the upstream side to the downstream side in the rotation direction of the rotating shaft, that is, in the circumferential direction, but maintains difficulty in bending (bending rigidity) in the radial direction. Is done. Therefore, by using a plate material that forms the top foil piece that is thicker than before, the same ease of bending in the circumferential direction as in the prior art is maintained, but in the radial direction, it is less likely to bend than in the conventional case. The bending to the back foil side can be suppressed.

  In the thrust bearing of the present invention, the inner peripheral end side thin portion and the outer peripheral end side thin portion formed thinner than the intermediate region are formed on the inner peripheral end side and the outer peripheral end side of the top foil piece. Therefore, it is possible to suppress the inner peripheral end side and the outer peripheral end side from easily rising to the thrust collar side. Therefore, according to the thrust bearing of the present invention, it is possible to prevent the top foil piece from approaching and coming into contact with the thrust collar and to be excellent in withstanding a high load.

It is a schematic diagram which shows an example of the turbomachine to which the thrust bearing which concerns on this invention is applied. It is a figure which shows 1st Embodiment of the thrust bearing which concerns on this invention, and is a side view of the thrust bearing of the state which pinched | interposed the thrust collar. 1 is a plan view of a first embodiment of a thrust bearing according to the present invention. It is a figure which shows 1st Embodiment of the thrust bearing which concerns on this invention, (a) is AA sectional view taken on the line in FIG. 3, (b) is the back surface in order to demonstrate the structure of a top foil piece. (C) is a plan view of a bump foil piece, (d) is a plan view and a side view for explaining the shapes of the top foil piece and the bump foil piece. It is explanatory drawing made to respond | correspond. It is a figure for demonstrating 2nd Embodiment of the thrust bearing which concerns on this invention, (a) is explanatory drawing which matched the top view and side view which show the back surface of a top foil piece, (b) is FIG. It is sectional drawing in the position corresponding to (a). It is a figure for demonstrating 3rd Embodiment of the thrust bearing which concerns on this invention, (a) is explanatory drawing which matched the top view and side view which show the back surface of a top foil piece, (b) is (a) ) Is a cross-sectional view taken along the line C-C of FIG. It is a figure which shows 4th Embodiment of the thrust bearing which concerns on this invention, (a) is a top view of a thrust bearing, (b) is DDA sectional view taken on the line of (a), (c) is top foil. It is explanatory drawing which matched the top view and the side view in order to demonstrate the shape of a piece and a bump foil piece.

Hereinafter, the thrust bearing of the present invention will be described in detail with reference to the drawings. In the following drawings, the scale of each member is appropriately changed to make each member a recognizable size.
FIG. 1 is a side view schematically showing an example of a turbo machine to which a thrust bearing of the present invention is applied. In FIG. 1, reference numeral 1 denotes a rotating shaft, 2 denotes an impeller provided at the tip of the rotating shaft, 3 Is a thrust bearing according to the present invention.

A thrust collar 4 is fixed to the rotary shaft 1 on the side where the impeller 2 is formed, and a pair of thrust bearings 3 is disposed on the thrust collar 4 so as to sandwich the thrust collar 4. .
The impeller 2 is disposed in a housing 5 on the stationary side, and has a tip clearance 6 between the impeller 2 and the housing 5.
The rotary shaft 1 is provided with a radial bearing 7 on the center side of the thrust collar 4.

“First Embodiment”
2, 3, and 4 (a) to 4 (d) are views showing a first embodiment of the thrust bearing 3 applied to the turbomachine having such a configuration, and FIG. 2 sandwiches the thrust collar 4. It is the side view of the thrust bearing 3 which looked at the principal part of the state in a cross section. 3 is a plan view of the thrust bearing 3, FIG. 4 (a) is a cross-sectional view taken along line AA in FIG. 3, and FIG. 4 (b) shows the back surface for explaining the configuration of the top foil piece. FIG. 4C is a plan view of the bump foil piece, FIG. 4D is a plan view for explaining the shapes of the top foil piece and the bump foil piece, and FIG. It is explanatory drawing which matched the side view.

  As shown in FIG. 2, in the first embodiment, the thrust bearing 3 </ b> A (3) is disposed on both sides of the thrust collar 4. The pair of thrust bearings 3 A (3) and the thrust bearing 3 A (3) have the same configuration, and have an annular shape (opposed to the disc-shaped thrust collar 4 fixed to the rotary shaft 1). (Cylindrical), and is provided by being extrapolated to the rotary shaft 1.

  The thrust bearing 3 </ b> A (3) includes a top foil 10 disposed to face the thrust collar 4, and a back foil disposed to face the surface of the top foil 10 opposite to the surface facing the thrust collar 4. 20 and an annular plate-like base plate 30 disposed on the back foil 20 on the side opposite to the top foil 10 side. In this embodiment, a cylindrical bearing spacer 40 indicated by a two-dot chain line is sandwiched between the base plate 30 and the base plate 30 of the pair of thrust bearings 3A (3) and thrust bearing 3A (3). 30 and the base plate 30 are connected via a bearing spacer 40 by fastening bolts 41. Further, the outer surface of one base plate 30 is fixed to the housing 5 by fastening bolts 41. Therefore, the pair of thrust bearings 3A (3) and 3A (3) are fastened with the thrust collar 4 sandwiched therebetween. It is fixed to the housing 5 by bolts 41.

  As shown in FIG. 3, the base plate 30 is an annular plate having a thickness of several millimeters and made of metal, and has a plurality of through holes 42 (in this embodiment) through which the fastening bolts 41 are inserted. 8). The base plate 30 is provided with a support region for supporting the back foil 20 and the top foil 10 on the surface on the thrust collar 4 side. In the present embodiment, as will be described later, the back foil 20 and the top foil 10 are both formed by a plurality (six) of the back foil pieces 21 and the top foil pieces 11, and therefore the base plate 30 has an inner peripheral portion. Are divided into six in the circumferential direction to form six support regions 31. In the present embodiment, these six support areas 31 are designed areas, and no boundary line or the like is provided between the adjacent support areas 31 and the support areas 31.

As shown in FIG. 2, the back foil piece 21 and the top foil piece 11 are arranged and supported in the respective support regions 31 in this order.
As shown in FIG. 3, the back foil 20 is formed by six back foil pieces 21 arranged in the circumferential direction of the base plate 30. These back foil pieces 21 are arranged on the respective support regions 31 of the base plate 30, and are thus arranged in the circumferential direction of the base plate 30. Further, these back foil pieces 21 are formed slightly smaller than the top foil pieces 11 to be described later. Therefore, the back foil pieces 21 are not exposed to the thrust collar 4 side on the base plate 30 as shown in FIG. It has been broken.

  The back foil 20 composed of these back foil pieces 21 is formed of a foil (thin plate) and elastically supports the top foil 10 (top foil piece 11). Examples of the back foil 20 include a bump foil, a spring foil described in Japanese Patent Application Laid-Open No. 2006-57652 and Japanese Patent Application Laid-Open No. 2004-270904, and Japanese Patent Application Laid-Open No. 2009-299748. A back foil or the like is used. Note that the spring foil described in JP 2006-57652 A and JP 2004-270904 A and the back foil described in JP 2009-299748 A are foils used for radial bearings. If these are developed in a planar shape and formed into an annular plate shape, a foil used for a thrust bearing is obtained.

  In the present embodiment, as shown in FIGS. 3, 4A, 4C, and 4D, the back foil 20 is made of a bump foil, and therefore the back foil piece 21 is made of a bump foil piece. The bump foil piece 21 (back foil piece) is a foil (metal thin plate) having a thickness of about several hundreds μm formed into a corrugated plate by press molding, and as shown in FIG. Is formed in a substantially trapezoidal shape (arc plate shape) in which the inner peripheral side and the outer peripheral side are each arcuate.

  As shown in FIGS. 4A and 4D, the bump foil pieces 21 formed in the corrugated plate shape in this way have valleys 22 in contact with the base plate 30 and peaks 23 in contact with the top foil pieces 11. It is arranged and formed. The trough 22 forms the bottom of the bump foil piece 21 (back foil piece 21), and the top (ridge line) of the peak 23 forms the top of the bump foil piece 21 (back foil piece 21). ing. Here, in the bump foil piece 21, the end side 21 a on the downstream side in the rotation direction of the rotating shaft 1 shown in FIG. 3 is a fixed side (bump foil fixed side) of the bump foil piece 21. The troughs 22 and the crests 23 are arranged in a direction orthogonal to the fixed side 21a (end side) of the bump foil piece 21 as shown in FIG. That is, the arrangement direction of the troughs 22 and the crests 23 is formed in a direction orthogonal to the fixed side 21a, so that the troughs 22 and the crests 23 extend in parallel with the fixed side 21a. Is formed.

  These valley portions 22 and peak portions 23 are formed at substantially equal pitches. Further, the height of the crest 23 is from the side opposite to the fixed side 21a toward the fixed side 21a, that is, on the downstream side in the rotation direction of the rotary shaft 1 (thrust collar 4) indicated by an arrow in FIG. As it goes, it is formed to increase by a predetermined height as shown in FIGS. 4 (a) and 4 (d).

  Further, as shown in FIG. 4C, the bump foil piece 21 has a radial direction on one side in the circumferential direction, in the present embodiment, on the opposite side to the end side 21a on the downstream side in the rotation direction of the rotary shaft 1. The end side 21a (fixed side) which is equally divided into four (plurality) and is on the other side is a continuous side continuous in the radial direction. Thus, the side opposite to the end side 21a is divided into four parts, so that the bump foil piece 21 is divided into four strip-like bump foil divided pieces 21b (back foil divided pieces) and fixed sides 21a (continuous sides). It is configured.

  Between the four strip-shaped bump foil division pieces 21b, slits 21c are respectively formed. In the present embodiment, the slits 21c are formed in an arc shape that forms a part of a circle concentric with the circle formed by the outer periphery of the bump foil 20. The widths of the slits 21c are set such that the bump foil divided pieces 21b adjacent in the radial direction can move independently without interfering with each other. Since one side of the bump foil piece 21 is divided into four strip-like bump foil divided pieces 21b by the slit 21c having such a width, the four strip-like bump foil divided pieces 21b move independently. It has become.

  The bump foil piece 21 may be divided into two, three, or five or more instead of four as long as the side opposite to the end side 21a (fixed side) is divided into a plurality of pieces. In addition, the divided pieces may be formed with different widths in the radial direction without being equally divided. For example, with respect to the bump foil divided pieces 21b arranged immediately below the inner peripheral end side thin portion 15 and the outer peripheral end side thin portion 16 of the top foil piece 11 described later, the corresponding inner peripheral end side thin portion 15 and outer peripheral end side are provided. You may form in the width | variety substantially equal to the width | variety in the radial direction of the thin part 16. FIG.

  Further, in the present embodiment, the bump foil piece 21 is formed with substantially uniform rigidity between the four bump foil divided pieces 21b without changing the rigidity particularly between the inner peripheral side and the outer peripheral side. . Moreover, the height of the top part of the peak part 23 on the same row | line | column is also formed substantially the same. Thereby, design and manufacture of the bump foil piece 21 are facilitated.

  Further, the bump foil piece 21 has an end side 21a on the downstream side in the rotation direction of the rotary shaft 1 substantially coincides with an end side 11a on the downstream side in the rotation direction of the rotary shaft 1 in the top foil piece 11 to be described later. Placed in position. The bump foil piece 21 is spot-welded (dot welding) to the base plate 30 and fixed along the direction of formation of the valley 22 that becomes the end side 21a.

At that time, since the end side 21a of the bump foil piece 21 is formed by one trough portion 22 that is continuous as a whole, the entire trough portion 22 can be easily welded. Therefore, the bump foil piece 21 can be easily fixed by welding.
The end side 21a can be fixed to the base plate 30 by, for example, screwing in addition to spot welding.

  The top foil 10 is also formed by six top foil pieces 11 arranged in the circumferential direction of the base plate 30 as shown in FIG. These top foil pieces 11 have an arc plate shape obtained by dividing an annular plate in the circumferential direction thereof, that is, a metal thin plate (foil) having a thickness of about several hundreds of μm, and the top side of the fan shape is cut off from the inner periphery. It is formed in a substantially trapezoidal shape in which the end side and the outer peripheral end side each have an arc shape. The circle formed by the arc on the inner peripheral end side of the top foil piece 11 is formed to be concentric with the circle formed by the arc on the outer peripheral end side of the top foil piece 11. The top foil pieces 11 having such shapes are arranged on the respective support regions 31 of the base plate 30 so as to cover the bump foil pieces 21 and are arranged at equal intervals in the circumferential direction of the base plate 30 so as to be substantially annular as a whole. The top foil 10 is formed by arrange | positioning at plate shape.

  The top foil piece 11 is formed slightly smaller than the support region 31 and slightly larger than the bump foil piece 21. Accordingly, the top foil pieces 11 are arranged in the respective support regions 31 so as to cover the upper surfaces thereof without interfering with each other and without exposing the bump foil pieces 21 to the thrust collar 4 side. However, the present invention is not limited to this, and the top foil piece 11 may be formed in the same size as the bump foil piece 21 or may be formed smaller than the bump foil piece 21.

  Further, the top foil piece 11 has a fixing portion 13 on the upstream side in the rotation direction of the rotary shaft 1 (thrust collar 4), and is fixed to the base plate 30 by the fixing portion 13. The fixing portion 13 is fixed to the base plate 30 by spot welding (dot welding) in the same manner as the end side 21 a of the bump foil piece 21. The fixing portion 13 can be fixed to the base plate 30 by, for example, screwing in addition to spot welding.

  The fixing portion 13 may be planar or linear as long as it is provided on the upstream side in the rotational direction of the rotating shaft 1 (thrust collar 4). However, in this embodiment, the fixing portion 13 is a straight line having a certain width. The fixed side 12 is formed in a shape.

  Further, as shown in FIG. 4A, the fixed side 12 side of the top foil piece 11 is bent so that a step corresponding to the height of the peak portion 23 of the bump foil piece 21 can be absorbed. The edge 11 a side of the fixed side 12 is placed on the peak portion 23. On the other hand, the end side 11a (trailing edge) side is merely a free end supported on the peak portion 23 of the bump foil piece 21 without being fixed.

  Further, the surface of the top foil piece 11 facing the back foil piece 21 is cut and etched by etching or the like, and as shown in FIG. An inner peripheral end side thin portion 15 and an outer peripheral end side thin portion 16 formed thinner than the intermediate region 14 between the inner peripheral end side and the outer peripheral end side are formed on the peripheral end side and the outer peripheral end side. ing. Accordingly, the top foil piece 11 is more easily bent at the inner peripheral end side and the outer peripheral end side than the intermediate region 14 between them.

  In the present embodiment, the boundary line 15 a between the inner peripheral end side thin portion 15 and the intermediate region 14 and the boundary line 16 a between the outer peripheral end side thin portion 16 and the intermediate region 14, that is, the stepped portions, are all the top foil pieces 11. It is circular arc shape along the circumferential direction of the inner peripheral end and outer peripheral end. That is, the boundary line 15a between the inner peripheral end side thin portion 15 and the intermediate region has an arc shape along the circumferential direction of the inner peripheral end of the top foil piece 11, and the outer peripheral end side thin portion 16 and the intermediate region 14 The boundary line 16 a has an arc shape along the circumferential direction of the outer peripheral end of the top foil piece 11.

  In the present embodiment, the fixed side 12 (fixed portion 13), the bent portion disposed adjacent to the fixed side 12, and the vicinity portion 17 of the processed portion include the inner peripheral end side thin portion 15 and The outer peripheral end side thin portion is not formed. This is because, on the fixed side 12 side, as shown in FIG. 2, there is no possibility that the top foil piece 11 contacts the thrust collar 4 because the height of the crest 23 of the bump foil piece 21 is low. And by manufacturing the top foil piece 11 by not forming a thin part in the vicinity part 17 in this way, when the fixed side 12 side is bent with a press, the vicinity part 17 that is in the vicinity of the processing part is grasped. Becomes easier and advantageous in terms of processing. For example, as shown in FIGS. 4 (a) and 4 (d), the formation range of the vicinity portion 17 that does not form the thin portion is a peak portion 23 closest to the fixed side 12 side at least from the fixed side 12 side. It is said that it takes about the top of

As shown in FIG. 4B, the radial width W2 of the top foil piece 11 of the inner peripheral end side thin portion 15 is 0.2 times to the radial width W1 of the entire top foil piece 11. 0.5 times, that is, W2 = 0.2W1 to 0.5W1, while suppressing the rising of the inner peripheral end side of the top foil piece 11 toward the thrust collar 4 side, as will be described later, The intermediate region 14 side of the piece 11 can be made to function as in the conventional case, which is preferable.
On the other hand, the radial width W3 of the top foil piece 11 of the outer peripheral end side thin portion 16 is 0.05 to 0.3 times the radial width W1 of the entire top foil piece 11, that is, W3. = 0.05W1 to 0.3W1, as described later, the intermediate region 14 side of the top foil piece 11 is conventionally controlled while suppressing the rising of the outer peripheral end side of the top foil piece 11 to the thrust collar 4 side. It can be made to function similarly to, and is preferable.

  However, with respect to the inner peripheral end side thin portion 15 and the outer peripheral end side thin portion 16, the radial width W2 of the inner peripheral end side thin portion 15 is larger than the radial width W3 of the outer peripheral end side thin portion 16. It is preferable to form wide (large). Since the peripheral speed of the thrust collar 4 on the inner peripheral end side of the thrust bearing 3 is slower than the peripheral speed on the outer peripheral end side, the portion on the inner peripheral end side of the top foil 10 that easily rises up to the thrust collar 4 side. The width of the portion on the outer peripheral end side of the top foil 10 that easily rises to the thrust collar 4 side due to the pressure of the fluid lubricating film being the same as the ambient pressure (for example, atmospheric pressure) at the outer peripheral end of the top foil 10. Wider than that. Therefore, by making the inner peripheral end side thin portion 15 wider in the radial direction than the outer peripheral end side thin portion 16, it is more effective that the top foil piece 11 approaches the thrust collar 4 and comes into contact therewith. Is prevented.

  Further, the amount of shaving of the inner peripheral end side thin portion 15 and the outer peripheral end side thin portion 16, that is, the thickness (thickness) of the inner peripheral end side thin portion 15 and the outer peripheral end side thin portion 16 and the thickness of the intermediate region 14. The difference may be about 10 to 30 μm. The thickness t2 of the inner peripheral end side thin portion 15 and the thickness t3 of the outer peripheral end side thin portion 16 are reduced by about 10 to 30 μm with respect to the thickness t1 of the intermediate region 14 by cutting such thickness. A gap corresponding to this difference can be formed between the apex of the crest portion 23 of the bump foil piece 21. This gap affects the fluid lubrication film formed between the thrust collar 4 and the top foil piece 11. Since this fluid lubrication film is also sufficiently thin, the gap is sufficient even if it is about 10 to 30 μm. Function. Further, with this amount of cutting, it is possible to satisfactorily suppress the rising to the thrust collar 4 side without making the inner peripheral end side and the outer peripheral end side of the top foil piece 11 extremely easy to bend. .

However, for the inner peripheral end side thin portion 15 and the outer peripheral end side thin portion 16, the thickness t2 of the inner peripheral end side thin portion 15 is formed to be thinner than the thickness t3 of the outer peripheral end side thin portion 16. Is preferred.
As described above, the area of the top foil piece 11 that easily rises to the thrust collar side is wider on the inner peripheral end side than on the outer peripheral end side. Therefore, by making the inner peripheral end side thin portion 15 thinner than the outer peripheral end side thin portion 16, the gap between the inner peripheral end side thin portion 15 and the bump foil piece 21 is changed to the outer peripheral end thin portion. Since it becomes larger than the said clearance gap of 16 direction, it is prevented more effectively that the top foil piece 11 approaches the thrust collar 4 and contacts this.

  In the present embodiment, as shown in FIG. 3, the bump foil pieces 21 are arranged so that the valley portions 22 and the mountain portions 23 of the bump foil pieces 21 are arranged in a direction intersecting with the fixed side 12 of the top foil pieces 11. ing. Accordingly, the valley portion 22 and the peak portion 23 extend in the length direction of the fixed side 12 and the end side 11a of the top foil piece 11, and in particular, extend in parallel to the end side 11a. Therefore, the top foil piece 11 is placed on the bump foil piece 21 so that the top foil piece 11 gradually moves from the fixed side 12 side toward the end side 11a along the arrangement direction of the peak portions 23. The bump foil piece 21 is disposed so as to be away from the inner surface at an initial inclination angle set by the peak portion 23 of the bump foil piece 21.

  Here, the initial inclination angle is an inclination angle of the top foil piece 11 with respect to the base plate 30 when the load is zero. Further, the inclination angle is an angle (inclination angle, gradient) θ determined by the height increase amount of the peak portion 23 of the bump foil piece 21 as shown in FIG. Therefore, when the load increases, the crest portion 23 of the bump foil piece 21 is pushed into the base plate 30 side and is flattened as a whole, so that the inclination angle θ becomes smaller than the initial inclination angle.

Next, the operation of the thrust bearing 3A (3) having such a configuration will be described.
In the present embodiment, the thrust bearing 3A is provided on both sides of the thrust collar 4 as shown in FIG. By providing the thrust collar 4 on both sides in this way, the amount of movement in the thrust direction can be suppressed as much as possible. That is, by reducing the amount of thrust movement, the tip clearance 6 shown in FIG. 1 can be narrowed, thereby improving the fluid performance as a turbomachine.

  In order to suppress the amount of movement in the thrust direction as much as possible, both thrust bearings 3A are installed close to the thrust collar 4 so that no large gap is generated. As a result, the top foil pieces 11 (top foil 10) of both thrust bearings 3A are slightly pressed against the thrust collar 4.

  When the rotary shaft 1 rotates in this state and the thrust collar 4 starts to rotate, the thrust collar 4 and the top foil piece 11 rub against each other and the surrounding fluid is pushed into the wedge-shaped space formed between the two. It is. When the thrust collar 4 reaches a certain rotational speed, a fluid lubricating film is formed between them. The top foil piece 11 (top foil 10) is pressed against the bump foil piece 21 (back foil 20) by the pressure of the fluid lubricating film, and the thrust collar 4 comes out of contact with the top foil piece 11 and rotates without contact. To come.

  When a thrust load is applied, the top foil piece 11 is further pushed to the bump foil piece 21 side, and the inclination angle θ of the top foil piece 11 becomes shallow (small). At this time, in the thrust bearing 3A (3), the peripheral speed of the thrust collar 4 on the outer peripheral end side is higher than the peripheral speed on the inner peripheral end side, so that the top foil piece 11 is on the inner peripheral end side where the peripheral speed is slow. Is easy to get up to the thrust collar 4 side. Further, on the outer peripheral side of the top foil piece 11, the pressure of the fluid lubricating film is the same as the ambient pressure (for example, atmospheric pressure) at the outer peripheral end. It is lower than the outer peripheral side (where it enters inward from the outer peripheral end). For this reason, the top foil piece 11 is easily raised not only at the inner peripheral end but also at the outer peripheral end.

  However, in the present embodiment, the inner peripheral end side thin portion 15 is formed on the inner peripheral end side of the top foil piece 11, and the outer peripheral end side thin portion 16 is formed on the outer peripheral end side. The outer peripheral end side is more easily bent than the intermediate region 14. Further, a gap is formed between the inner peripheral end side thin portion 15 and the bump foil piece 21 on the inner peripheral end side, and a gap is formed between the outer peripheral end side thin portion 16 and the bump foil piece 21 on the outer peripheral end side. Therefore, both the inner peripheral end side and the outer peripheral end side are easily pushed into the bump foil piece 21 side.

  At that time, on the inner peripheral end side, it is difficult for the bump foil piece 21 to generate a force to push the top foil piece 11 back to the thrust collar 4 side by the gap. Therefore, since the peripheral speed of the thrust collar 4 on the inner peripheral end side of the thrust bearing 3A (3) is slower than the peripheral speed on the outer peripheral end side, the inner peripheral end side can easily rise to the thrust collar 4 side. Is suppressed. That is, the inner peripheral end side is difficult to rise to the thrust collar 4 side. Further, even on the outer peripheral end side, the bump foil piece 21 is less likely to generate a force that pushes the top foil piece 11 back to the thrust collar 4 side due to the gap. Therefore, the pressure of the fluid lubricating film at the outer peripheral end of the top foil piece 11 is the same as the ambient pressure (for example, atmospheric pressure), thereby preventing the outer peripheral end side from easily rising to the thrust collar 4 side. That is, it is difficult for the outer peripheral end side to get up to the thrust collar 4 side.

Further, even if the inner peripheral end side is pushed into the bump foil piece 21 side and the gap disappears, the spring force of the bump foil piece 21 is weakened by the amount of the gap as compared with the intermediate region 14, so the inner peripheral end side. Is difficult to get up to the thrust collar 4 side as described above. Similarly, since the spring force of the bump foil piece 21 is weaker at the outer peripheral end side than at the intermediate region 14, the outer peripheral end side is also difficult to get up to the thrust collar 4 side as described above.
Therefore, even if the thrust load is further increased and the film thickness of the fluid lubricating film is further reduced, the top foil piece 11 becomes difficult to contact the thrust collar 4 and as a result, a higher thrust load can be received.

  In the thrust bearing 3A (3) of the present embodiment, the inner peripheral end side thin portion 15 thinner than the intermediate region 14 is formed on the inner peripheral end side of the top foil piece 11 so that the inner peripheral end side is easily bent. Further, the outer peripheral end side thin portion 16 which is thinner than the intermediate region 14 is also formed on the outer peripheral end side so that the outer peripheral end side is easily bent, and a gap is formed between the inner peripheral end side and the outer peripheral end side between the bump foil pieces 21. Therefore, it is possible to make it difficult for the bump foil piece 21 to push back the top foil piece 11 toward the thrust collar 4 side on both the inner peripheral end side and the outer peripheral end side.

  Therefore, it is possible to suppress the inner peripheral end side from easily rising to the thrust collar 4 side because the peripheral speed of the thrust collar 4 on the inner peripheral end side is slower than the peripheral speed on the outer peripheral end side. Further, since the pressure of the fluid lubricating film becomes the same as the ambient pressure (for example, atmospheric pressure) at the outer peripheral end of the top foil piece 11, it is possible to prevent the outer peripheral end side from easily rising to the thrust collar 4 side. Therefore, it is possible to prevent the top foil piece 11 from approaching the thrust collar 4 and coming into contact therewith, thereby preventing a reduction in bearing life and seizure. Moreover, since the film thickness of the fluid lubrication film on the inner peripheral end side and the outer peripheral end side does not become extremely thin, it is excellent to withstand a high load.

  In addition, since the inner peripheral end side thin portion 15 and the outer peripheral end side thin portion 16 are formed in this way to prevent a decrease in bearing life and seizure, the bump foil piece (back foil piece) 21 is used as the inner peripheral end side. And those having the same rigidity and the same peak height on the outer peripheral end side can be used. Thereby, the design and manufacture can be facilitated. For example, the bump foil piece 21 can be easily manufactured by press molding. Further, since the bump foil piece 21 having the same mountain height between the inner and outer circumferences can be used, dimensional management becomes easy. Therefore, the design and production of the bump foil piece 21 and the dimensional management are facilitated as described above, so that the production cost of the bump foil piece 21 can be reduced.

“Second Embodiment”
Next, a second embodiment of the thrust bearing of the present invention will be described.
The thrust bearing of the second embodiment is mainly different from the thrust bearing 3A (3) of the first embodiment in that a top foil piece having the structure shown in FIGS. 5A and 5B is used. is there. Here, FIG. 5A is an explanatory view in which a plan view showing the back surface of the top foil piece 50 and a side view are associated with each other, and FIG. 5B is a cross-sectional view taken along line AA in FIG. It is sectional drawing in the same position as 4 (a).

  The top foil piece 50 shown in FIGS. 5 (a) and 5 (b) is different from the top foil piece 11 shown in FIG. 4 (b) in that the fixed side 12 of the top foil piece 50 and its vicinity, that is, the fixed side. 12 and the vicinity located on the downstream side in the rotation direction of the rotary shaft 1 with respect to the fixed side 12 is a fixed portion side thin portion 18 formed thinner than the intermediate region 14 and the vicinity portion 17. It is in.

  The fixed portion side thin portion 18 is formed linearly along the length direction of the fixed side 12 and is formed by etching or the like, similarly to the inner peripheral end side thin portion 15 and the outer peripheral end side thin portion 16. Has been. The fixed portion side thin portion 18 can be formed at the same thickness as the inner peripheral end side thin portion 15 or the outer peripheral end side thin portion 16 by the same etching process. In addition, when it is desired to form a thickness (thinness) different from those of the inner peripheral end side thin portion 15 and the outer peripheral end side thin portion 16, the inner peripheral end side thin portion 15 and the outer peripheral end side thin portion 16 are etched. Is a separate process, and the fixed portion side thin portion 18 can also be formed.

  In the present embodiment, the fixed portion side thin portion 18 is made to be bent at the inner peripheral end side thin portion 15 or the outer peripheral end so that the fixed portion side thin portion 18 can bend the downstream side of the rotating shaft 1 more easily than the fixed portion side thin portion 18. It is preferable to form it thinner than the side thin part 16. Therefore, etching processing is performed a plurality of times on the plate material (thin plate) of the top foil piece 50, and the processing of the inner peripheral end side thin portion 15 and the outer peripheral end side thin portion 16 and the processing of the fixed portion side thin portion 18 are separately performed. Do. The thickness of the fixed portion side thin portion 18 is preferably about 50% to 70% of the thickness (about several hundred μm) of the intermediate region 14 or the like that is not etched by etching. By forming in such a thickness, the downstream side of the rotating shaft 1 can be more easily bent.

  Further, the fixed portion-side thin portion 18 does not reach the apex (ridge line) of the peak portion 23 closest to the fixed side 12 among the peak portions 23 with respect to the back foil piece 21 shown in FIG. Is formed. That is, the fixed portion side thin portion 18 includes the fixed side 12 and has a width set and formed so as to be positioned between the fixed side 12 and the apex (ridge line) of the peak portion 23 on the fixed side 12 side. Yes. As a result, the top foil piece 50 is placed on the peak portion 23 as a whole, and the portions other than the fixed portion side thin portion 18, the inner peripheral end side thin portion 15, and the outer peripheral end side thin portion 16 are equally supported by these. Thus, the inclination angle θ shown in FIG. 4D is maintained. Further, by forming the fixed portion side thin portion 18, the end side 11 a side can be inclined (inclined) more easily and smoothly than the fixed portion side thin portion 18. Furthermore, by forming such a fixed portion side thin portion 18, it is possible to increase the thickness of portions other than the fixed portion side thin portion 18 as compared with the conventional case.

  In the present embodiment, since the fixed portion side thin portion 18 is formed in the vicinity of the fixed side 12 and the downstream side in the rotation direction of the top foil piece 50, the end side 11a when a load is applied. The side can be inclined more easily and smoothly. Therefore, even after the rotation shaft 1 starts to rotate, the top foil piece 50 can be easily and smoothly inclined, so that the optimum inclination angle can be easily obtained and the load capacity is improved.

  Here, since the pressure of the fluid lubricating film is increased when receiving a high thrust load, the top foil piece 50 is positioned on a portion that is not directly supported by the bump foil piece 21, that is, on the valley portion 22 of the bump foil piece 21. There is a possibility that the part to be bent is deflected, the pressure escapes from here, and the load capacity decreases.

  However, in this embodiment, since the fixed portion side thin portion 18 is formed on the fixed side 12 side of the top foil piece 50, the top foil piece 50 is top compared to the conventional case without obstructing the tilting (bending) movement. It is possible to increase the thickness of the plate material of the foil piece 50 (the thickness of the intermediate region 14). Therefore, by thickening the plate thickness of the top foil piece 50 in this way, it is possible to reduce the bending at the portion not supported by the bump foil piece 21 and to suppress the load capacity from being lowered.

“Third Embodiment”
Next, a third embodiment of the thrust bearing of the present invention will be described.
The thrust bearing according to the third embodiment is mainly different from the thrust bearing according to the second embodiment in that a top foil piece having the configuration shown in FIGS. 6A to 6C is used. Here, FIG. 6A is an explanatory diagram in which a plan view showing the back surface of the top foil piece 60 and a side view (a cross-sectional view taken along the line B-B in the plan view) are associated with each other, and FIG. FIG. 6A is a cross-sectional view taken along the line CC of FIG. 6A, and FIG.

  The top foil piece 60 shown in FIGS. 6A to 6C is different from the top foil piece 50 shown in FIGS. 5A and 5B in that the bump foil piece 21 shown in FIG. It is the point which formed the trough side thin part 19 formed thinly in the location facing the trough part 22 compared with the location facing the peak part 23. As shown in FIG.

  As shown in FIG. 6A, the valley-side thin portion 19 is formed in a groove shape extending from the outer peripheral end of the top foil piece 60 to the inner peripheral end or the side end. Similarly to the portion 15, the outer peripheral end side thin portion 16, and the fixed portion side thin portion 18, it is formed by etching or the like. Moreover, it is preferable to make the valley side thin portion 19 as thin as the fixed portion thin portion 18. Therefore, when the top foil piece 60 is manufactured, the etching process is performed a plurality of times on the plate material of the top foil piece 60 in the present embodiment. For example, the valley-side thin portion 19 and the fixed portion-side thin portion 18 are formed by the same etching process, then the inner peripheral end-side thin portion 15 is formed by another etching process, and then the outer peripheral end-side thin wall The part 16 is formed by another etching process. In forming the inner peripheral end side thin portion 15 and the outer peripheral end side thin portion 16, the portion where the valley portion thin portion 19 is formed is not etched, and only at a position avoiding the valley portion thin portion 19. An etching process is selectively performed.

Here, the above-mentioned “location facing the valley 22 of the bump foil piece 21” is defined as follows, for example.
That is, as shown in FIG. 6C, the apex of the crest 23 of the bump foil piece 21 is H, and the position of the crest 23 on the trough 22 side, that is, the boundary between the crest 23 and the trough 22 is L. Furthermore, if the intermediate point on the base plate 30 between the vertex H and the boundary line L is M, the two intermediate points M and M sandwiching the valley 22 are defined as locations facing the valley 22. Therefore, as shown in FIG. 6C, the valley side thin portion 19 is formed at a location corresponding to the intermediate point M between the top foil pieces 60. Although FIG. 6C shows the case where the valley portion 22 has a width, when the valley portion 22 is merely a bent portion and does not have a width, the boundary line L is adjacent. The above-described definition can be used as it is only by being common between the matching ridges 23 and ridges 23.

In the present embodiment, since the fixed portion side thin portion 18 is formed as in the second embodiment, it is possible to increase the thickness of the plate material of the top foil piece 60 as compared with the conventional case.
Here, when the pressure of the fluid lubrication film acts on the top foil piece 60, the central portion in the radial direction sandwiched between the inner peripheral end and the outer peripheral end of the top foil piece 60 is easily bent (dented) toward the back foil piece 21. Become. When such bending increases, the pressure of the fluid lubricating film decreases at the same portion, and the load capacity decreases.

  That is, the pressure of the fluid lubricating film formed between the top foil piece 60 and the thrust collar 4 is the pressure of the fluid around the top foil piece 60 (ambient pressure) at the inner peripheral end and the outer peripheral end of the top foil piece 60. On the other hand, the pressure of the fluid lubricating film is higher than the ambient pressure at the radial center between the inner peripheral end and the outer peripheral end of the top foil piece 60. When the fluid lubricating film has such a pressure distribution, the center portion is greatly bent (depressed) toward the back foil piece 21 side as compared with the inner peripheral end side and the outer peripheral end side. At that time, the bearing gap (the thickness of the fluid lubrication film) increases in the central portion that is greatly bent, so that the pressure of the fluid lubrication film in the same portion decreases, and the load capacity decreases as described above.

Therefore, in the present embodiment, by forming the valley side thin portion 19, the top foil piece 60 is easily bent in the circumferential direction from the upstream side to the downstream side in the rotational direction of the rotating shaft 1, that is, in the radial direction. The bending difficulty (bending rigidity) is maintained at the same bending difficulty as before the formation of the valley-side thin portion 19. Therefore, by using a plate material forming the top foil piece 60 that is thicker than the conventional plate material, the same ease of bending in the circumferential direction as in the conventional case is maintained, but in the central portion, it is less likely to bend in the radial direction. The bending to the back foil piece 21 side can be suppressed.
Therefore, in this embodiment, it can suppress that the load capability becomes low by suppressing the pressure of the fluid lubricating film in the site | part by suppressing the bending in the radial direction center part.

“Fourth Embodiment”
Next, a fourth embodiment of the thrust bearing of the present invention will be described.
The thrust bearing 3B (3) of the fourth embodiment is mainly different from the thrust bearing 3A (3) of the first embodiment as shown in FIGS. 7 (a) to 7 (c). This is the point that the inclined surface 32 is formed on 31 and the height of the peak portion 23 of the bump foil piece 21 are all made the same. 7A is a plan view of the thrust bearing 3, FIG. 7B is a cross-sectional view taken along the line DD of FIG. 7A, and FIG. 7C is a top foil piece and a bump foil piece. It is explanatory drawing which matched the top view and the side view in order to demonstrate a shape.

  In the present embodiment, as shown in FIG. 7A, the entire region supporting the bump foil piece 21 and the top foil piece 11 in the support region 31 is the downstream end from the fixed side 12 side of the top foil piece 11. The inclined surface 32 has a height that increases toward the side 11a. That is, the inclined surface 32 is formed so as to be inclined in a direction orthogonal to the end side 11a as shown in FIG.

  Further, the bump foil pieces 21 are formed in a corrugated plate shape in which the valley portions 22 that contact the base plate 30 and the peak portions 23 that contact the top foil pieces 11 are alternately arranged, as in the first embodiment. . However, in this embodiment, as shown in FIGS. 7B and 7C, the heights of the peak portions 23 are all formed to be the same.

  Moreover, about the trough part 22 and the peak part 23, it arranges in the direction which cross | intersects the fixed side 12 of the top foil piece 11 similarly to the said embodiment. That is, the arrangement direction of the valley portions 22 and the mountain portions 23 is set to a direction intersecting with the fixed side 12 and coincides with the inclination direction of the inclined surface 32. As a result, the peak portion 23 of the bump foil piece 21 has a predetermined height along the inclination direction of the inclined surface 32 of the base plate 30, that is, toward the downstream side in the rotation direction of the rotary shaft 1. It is getting higher. That is, it is apparently the same as the first embodiment. Accordingly, the top foil piece 11 disposed on the bump foil piece 21 is formed in the same manner as the first embodiment in the inclination angle θ. In the present embodiment, the inclination angle θ is determined by the inclination angle θ of the inclined surface 32 as shown in FIG.

  Also in the thrust bearing 3B (3) of the present embodiment, the inner peripheral end side thin portion 15 and the outer peripheral end side thin portion 16 are formed on the top foil piece 11 similarly to the top foil piece 11 shown in FIG. The inner peripheral end side and the outer peripheral end side are easily bent, and a gap is formed between the inner peripheral end side and the outer peripheral end side with the bump foil piece 21. In any of the outer peripheral ends, it is possible to make it difficult for the bump foil piece 21 to generate a force that pushes the top foil piece 11 back to the thrust collar 4 side. Therefore, it is possible to suppress the inner peripheral end side from easily rising to the thrust collar 4 side because the peripheral speed of the thrust collar 4 on the inner peripheral end side is slower than the peripheral speed on the outer peripheral end side. Further, since the pressure of the fluid lubricating film becomes the same as the ambient pressure (for example, atmospheric pressure) at the outer peripheral end of the top foil piece 11, it is possible to prevent the outer peripheral end side from easily rising to the thrust collar 4 side. Therefore, it is possible to prevent the top foil piece 11 from approaching the thrust collar 4 and coming into contact therewith, thereby preventing a reduction in bearing life and seizure. Moreover, since the film thickness of the fluid lubrication film on the inner peripheral end side and the outer peripheral end side does not become extremely thin, it is excellent to withstand a high load.

  In addition, an inclined surface 32 is formed in each support region 31 of the base plate 30 so that the heights of the crests 23 of the bump foil pieces 21 are all the same, and the arrangement direction of the crests 23 is set to the inclination direction of the inclined surface 32. Therefore, by arranging the top foil piece 11 on the inclined surface 32 via the bump foil piece 21, the height of the top foil piece 11 can be accurately changed along the inclined surface 32. it can. That is, a predetermined inclination angle θ can be given to the top foil piece 11. Further, at this time, the bump foil piece 21 may be produced at a constant height without changing the height of the peak portion 23, and therefore the processing cost can be suppressed. Therefore, according to this thrust bearing 3B (3), processing can be facilitated, mass productivity can be improved, and cost can be reduced. Further, since machining becomes easy and variation is reduced, it is easy to obtain bearing performance (for example, bearing load capability) predicted at the time of design.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.
For example, in the above embodiment, the back foil 20 and the top foil 10 are each composed of six back foil pieces 21 (bump foil pieces 21) and top foil pieces 11, and accordingly, six support regions 31 of the base plate 30 are also provided. Although formed (set), the number of back foil pieces 21 (bump foil pieces 21) and top foil pieces 11 may be five or less or seven or more as long as there are a plurality of pieces. In this case, the number of support regions 31 is naturally adjusted to the number of back foil pieces 21 (bump foil pieces 21) and top foil pieces 11.

  Moreover, in the said 4th Embodiment, although the top foil piece 11 of 1st Embodiment is used as a top foil piece, it replaces with this and the top foil piece 50 of 2nd Embodiment, or the top of 3rd Embodiment. A foil piece 60 can also be used.

  Furthermore, when the inclined surface 32 is formed in the support region 31 of the base plate 30 in the fourth embodiment, instead of the entire surface on which the bump foil pieces 21 are placed being the inclined surface 32, a part of the surface is a flat surface. You may arrange | position a part of piece 21 on the inclined surface 32, and a remainder on a flat surface. In that case, the flat surface may be formed on the upper side (the end side 11a side) of the inclined surface, or may be formed on the lower side (the fixed side 12 side). Further, flat surfaces may be formed on both sides of the inclined surface.

Moreover, about the inner peripheral end side thin part 15 and the outer peripheral end side thin part 16, the boundary line 15a of these and the intermediate | middle area | region 14 and the boundary line 16a are shown in FIG. In addition to the arc shape along the circumferential direction of the inner peripheral end and the outer peripheral end, various forms such as a linear shape from the upstream side to the downstream side in the rotational direction of the rotating shaft 1 can be adopted.
Further, the thickness of the inner peripheral end side thin portion 15 and the outer peripheral end side thin portion 16 is not formed to a uniform thickness, for example, from the boundary line 15a side to the outer side (the inner peripheral end side or the outer peripheral end side). The surface of the inner peripheral end side thin portion 15 or the outer peripheral end side thin portion 16 that faces the back foil piece 21 may be inclined so that the wall thickness gradually decreases.
In addition to the above embodiments, various forms such as the shape of the top foil piece and the bump foil piece, the arrangement of the top foil piece and the bump foil piece on the support region, and the inclination direction of the inclined surface can be adopted. is there.

  Further, as described above, the bump foil piece 21 (back foil piece 21) may be divided into two or more pieces without being divided into four pieces as described above. Good. Further, when the divided pieces are formed, they may be formed in a completely independent form without forming continuous sides, and thus without connecting the divided pieces.

  In addition to the above embodiments, various forms such as the shape of the top foil piece and the bump foil piece, the arrangement of the top foil piece and the bump foil piece on the support region, and the inclination direction of the inclined surface can be adopted. is there.

DESCRIPTION OF SYMBOLS 1 ... Rotary shaft 3, 3A, 3B ... Thrust bearing, 4 ... Thrust collar, 10 ... Top foil, 11 ... Top foil piece, 11a ... End side, 12 ... Fixed side, 13 ... Fixed part, 14 ... Middle area | region, DESCRIPTION OF SYMBOLS 15 ... Inner peripheral edge side thin part, 15a ... Boundary line, 16 ... Outer peripheral edge side thin part, 16a ... Boundary line, 17 ... Neighborhood part, 18 ... Fixed part side thin part, 19 ... Valley part thin part, 20 ... Back foil, 21 ... Back foil piece (bump foil piece), 21a ... End side (continuous side), 21b ... Split piece, 22 ... Valley, 23 ... Mountain, 30 ... Base plate, 31 ... Support area, 32 ... Inclined 50, top foil piece, 60 ... top foil piece

Claims (7)

A thrust bearing disposed opposite to a thrust collar provided on a rotating shaft,
A top foil disposed opposite the thrust collar;
A back foil that is disposed to face a surface of the top foil opposite to the surface that faces the thrust collar and supports the top foil;
An annular plate-like base plate that is disposed on the side of the back foil opposite to the top foil and supports the back foil;
The back foil is formed by a plurality of back foil pieces arranged in the circumferential direction of the base plate,
The top foil is formed by a plurality of top foil pieces respectively disposed on the back foil pieces,
The top foil piece is formed with a fixed portion fixed to the base plate on the upstream side in the rotation direction of the rotating shaft, and a surface facing the back foil piece is thinned so that an inner periphery thereof is formed. The inner peripheral end side thin portion and the outer peripheral end side thin portion formed thinner than the intermediate region between the inner peripheral end side and the outer peripheral end side are formed on the end side and the outer peripheral end side. A featured thrust bearing.   The thrust bearing according to claim 1, wherein the inner peripheral end side thin portion has a larger radial width than the outer peripheral end side thin portion.   The thrust bearing according to claim 1, wherein the inner peripheral end side thin portion is thinner than the outer peripheral end side thin portion.   4. The back foil piece according to claim 1, wherein one side in the circumferential direction is divided into a plurality in the radial direction and the other side is a continuous side continuous in the radial direction. The thrust bearing according to any one of the above.   The fixed portion side thin portion formed thinner than the intermediate region is formed downstream of the fixed portion in the rotation direction of the rotation shaft at the fixed portion of the top foil and in the vicinity of the fixed portion. The thrust bearing according to any one of claims 1 to 4, characterized in that: The top foil piece is formed in an arc plate shape obtained by dividing an annular plate in its circumferential direction,
The boundary line between the inner peripheral end side thin portion and the intermediate region has an arc shape along the circumferential direction of the inner peripheral end of the top foil piece,
3. The thrust bearing according to claim 1, wherein a boundary line between the outer peripheral end-side thin portion and the intermediate region has an arc shape along a circumferential direction of the outer peripheral end of the top foil piece. The fixed portion of the top foil is formed including a linear fixed side located on the upstream side in the rotation direction of the rotating shaft,
The back foil piece is formed by corrugated bump foil pieces in which crests and troughs are alternately formed, and the arrangement direction of the crests is arranged to intersect the fixed side,
In the top foil piece, a part of the surface facing the bump foil piece was thinned, so that the top foil piece was formed thinner at a location facing the valley than at a location facing the peak. The thrust bearing according to any one of claims 1 to 3, wherein a valley-side thin portion is formed.

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