WO2015041233A1 - スラスト軸受 - Google Patents
スラスト軸受 Download PDFInfo
- Publication number
- WO2015041233A1 WO2015041233A1 PCT/JP2014/074508 JP2014074508W WO2015041233A1 WO 2015041233 A1 WO2015041233 A1 WO 2015041233A1 JP 2014074508 W JP2014074508 W JP 2014074508W WO 2015041233 A1 WO2015041233 A1 WO 2015041233A1
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- WIPO (PCT)
- Prior art keywords
- foil piece
- top foil
- fixed
- thrust bearing
- piece
- Prior art date
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C17/00—Sliding-contact bearings for exclusively rotary movement
- F16C17/04—Sliding-contact bearings for exclusively rotary movement for axial load only
- F16C17/042—Sliding-contact bearings for exclusively rotary movement for axial load only with flexible leaves to create hydrodynamic wedge, e.g. axial foil bearings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C2240/00—Specified values or numerical ranges of parameters; Relations between them
- F16C2240/40—Linear dimensions, e.g. length, radius, thickness, gap
- F16C2240/46—Gap sizes or clearances
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C2360/00—Engines or pumps
Definitions
- the present invention relates to a thrust bearing.
- This application claims priority based on Japanese Patent Application No. 2013-194441 for which it applied to Japan on September 19, 2013, and uses the content here.
- a thrust bearing As a bearing for a high-speed rotating body, a thrust bearing is known that is disposed so as to face a thrust collar provided on a rotating shaft.
- a foil-type thrust bearing that is, a thrust foil bearing is well known.
- This thrust foil bearing is formed of a flexible foil (thin metal plate) on the bearing surface so that it can absorb the movement of the rotating shaft (axial displacement and inclination of the thrust collar) generated by vibration and impact.
- a foil structure for flexibly supporting the bearing surface is provided under the surface.
- an annular (annular) bearing surface is formed by a plurality of individual foil pieces (top foil pieces) obtained by dividing an annular plate in the circumferential direction.
- 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 (thickness of about 100 ⁇ m) is arranged with an inclination angle with respect to the thrust collar, whereby the bearing gap between the thrust collar and the top foil piece is formed in a wedge shape in side view. The 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.
- the top foil piece In the top foil piece, only the edge on the upstream side in the rotation direction of the thrust collar (rotating shaft) is fixed to the base plate, and this edge is configured as a fixed edge.
- the top foil When the bearing load increases, the top foil is displaced to be horizontal (parallel to the supported surface of the thrust collar) with this fixed side (upstream end side) as a fulcrum, and the inclination angle becomes smaller.
- the thrust bearing generates the maximum load capacity when it reaches about 0.1 °.
- the bump foil piece is arranged so that the ridgeline 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) It is fixed. That is, the upstream end of the bump foil piece is a free end.
- the bump foil piece Since the bump foil piece is arranged and fixed in this way, the pressure of the fluid lubricating film generated on the top foil piece is increased on the narrow side (downstream side) of the bearing gap. Therefore, the load capacity of the thrust bearing can be increased by supporting this portion with high rigidity.
- Patent Documents 2 to 4 disclose a thrust bearing having a top foil and a bump foil.
- Patent Document 5 discloses a thrust bearing having a bearing foil, and an introduction groove is formed on the bearing surface of the bearing foil.
- the pressure of the fluid lubricating film formed between the top foil piece and the thrust collar is close to the fluid pressure (ambient pressure) around the top foil piece.
- the pressure of the fluid lubricating film is higher than the ambient pressure at the radial center between the inner and outer peripheral ends of the top foil piece.
- 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 center portion decreases, and the load capacity of the bearing decreases as described above. There is a case.
- the thickness of the top foil piece for example, in order to reduce the deflection (dent) in the central portion in the radial direction.
- the slope deformability in the circumferential direction of the top foil piece is impaired, and there is a possibility that the inclination angle of the top foil piece becomes difficult to be about 0.1 ° which is close to the horizontal as described above. For this reason, since it becomes difficult to obtain the maximum load capacity of the bearing, the load capacity may also decrease.
- the present invention has been made in view of the above circumstances, and an object thereof is to provide an excellent thrust bearing capable of preventing a reduction in load capacity.
- the thrust bearing 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 top
- the foil is disposed opposite to the surface opposite to the surface facing the thrust collar and supports the top foil.
- the back foil is disposed on the side opposite to the side closer to the top foil. And an annular plate-like base plate that supports the back foil.
- the back foil has a plurality of back foil pieces arranged in the circumferential direction of the base plate.
- the top foil has a plurality of top foil pieces respectively disposed on the plurality of back foil pieces.
- the top foil piece is formed with a fixing portion fixed to the base plate on the upstream side in the rotation direction of the rotating shaft, and the surface facing the back foil piece is removed.
- a thin portion extending from the outer peripheral end of the piece to the inner peripheral end or the side end is formed.
- a thin portion extending from the outer peripheral end to the inner peripheral end or the side end of the top foil piece is formed by removing the surface facing the back foil piece.
- the top foil piece is easily bent at the thin portion, and thus is easily bent from the upstream side to the downstream side in the rotation direction of the rotating shaft, that is, in the circumferential direction.
- the bending difficulty bending rigidity
- the thin portion in the thrust bearing of the first aspect, is located downstream of the fixed portion and in the rotation direction of the rotating shaft from the fixed portion in the vicinity of the fixed portion and the fixed portion.
- the fixed part side thin part extended from the outer peripheral end of the top foil piece formed to the inner peripheral end is included.
- the thin-walled portion is formed from the outer peripheral end of the top foil piece formed on the fixed portion and in the vicinity of the fixed portion on the downstream side in the rotation direction of the rotating shaft from the fixed portion.
- the fixed part side thin part extended to the peripheral end is included.
- the portion on the downstream side in the rotation direction of the rotating shaft of the top foil piece can be easily and smoothly displaced by the thin portion on the fixed portion side, and therefore, for example, the thrust collar is sandwiched between the pair of top foils. In this case, the starting torque of the rotating shaft is reduced. Further, since the top foil piece is easily and smoothly displaced even after the rotation shaft starts to rotate, the optimum inclination angle of the top foil piece is easily obtained, and the load capacity of the bearing is improved.
- the fixing portion includes a linear fixed side located on the downstream side in the rotation direction of the rotating shaft.
- the back foil piece is formed of 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.
- the said thin part contains the trough part side thin part formed in the location facing the said trough part thinly compared with the location facing the said peak part.
- the thin portion includes the valley portion-side thin portion
- the diameter The bending toward the back foil at the center can be suppressed by making it difficult to bend in the direction.
- the top foil piece is easily bent by the valley-side thin portion, so that the inclination angle of the top foil piece easily becomes the optimum angle, and the bearing Increases load capacity.
- the height of the peak portion increases from the fixed side toward the downstream side in the rotational direction of the rotary shaft. It is formed as follows.
- the top foil piece can be elastically supported by the bump foil piece. Further, the height of the top foil piece can be changed in accordance with the peak portion of the bump foil piece whose height has changed.
- the base plate includes a top foil piece disposed in each support region that supports the back foil piece.
- An inclined surface whose height increases from the fixed side toward the end side on the downstream side in the rotation direction of the rotary shaft is formed.
- the back foil piece is formed by corrugated bump foil pieces in which peaks and valleys are alternately formed.
- the arrangement direction of the peaks is arranged so as to coincide with the inclination direction of the inclined surface.
- the top foil piece can be elastically supported by the bump foil piece.
- the ridgeline of the peak closest to the downstream edge of the bump foil can be parallel to the thrust collar supported surface, the downstream edge of the top foil supported by this peak is always parallel to the thrust collar. It becomes easy to.
- the bump foil piece is fixed to the base plate at an end on the downstream side in the rotation direction of the rotating shaft. ing.
- the top foil piece on the downstream side in the rotation direction in order to increase the pressure of the fluid lubrication film generated on the top foil piece on the narrow side of the bearing gap, that is, on the downstream side in the rotation direction of the rotating shaft, the top foil piece on the downstream side in the rotation direction.
- the side can be supported with high rigidity, thereby increasing the load capacity of the bearing.
- the top foil piece is easily bent at the thin portion, and the rotating shaft rotates. It can be easily bent from the upstream side to the downstream side, that is, in the circumferential direction.
- it since it is hardly affected by the thin portion in the radial direction, it is possible to maintain the same bending difficulty as before the formation of the thin portion without changing the bending difficulty (bending rigidity). Therefore, by using a thicker plate material than in the past to form the top foil piece, it is less likely to bend in the radial direction while maintaining the same ease of bending in the circumferential direction as in the conventional case. Bending toward the back foil can be suppressed. Thereby, the fall of the load capability of a thrust bearing can be prevented.
- FIG. 3C is a cross-sectional view taken along line 3C-3C in FIG. 3A.
- FIG. 4B is a cross-sectional view taken along line 4B-4B in FIG. 4A. It is explanatory drawing of a trough part side thin part. It is a figure for demonstrating the thrust bearing which concerns on 3rd Embodiment of this invention, and is the explanatory drawing which matched the top view and side view which show the back surface of a top foil piece.
- FIG. 5B is a cross-sectional view taken along line 5B-5B in FIG. 5A.
- FIG. 6C is a cross-sectional view taken along line 6C-6C in FIG. 6A. It is explanatory drawing which matched the top view and side view in order to demonstrate the shape of a bump foil piece.
- 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.
- reference numeral 1 denotes a rotating shaft
- reference numeral 2 denotes an impeller provided at a tip portion of the rotating shaft
- Reference numeral 3 denotes a thrust bearing according to the present invention.
- a thrust collar 4 is fixed to the rotary shaft 1 in the vicinity of the tip where the impeller 2 is formed, and a pair of thrust bearings 3 are arranged so as to sandwich the thrust collar 4. Further, the impeller 2 is disposed in the housing 5 on the stationary side, and a tip clearance 6 is formed between the impeller 2 and the housing 5. Further, the rotary shaft 1 is provided with a radial bearing 7 in a portion closer to the center than the thrust collar 4.
- FIG. 2 is a side view of the thrust bearing 3 with the thrust collar 4 interposed therebetween.
- FIG. 3A is a plan view of the thrust bearing 3 partially in cross section.
- FIG. 3B is a plan view showing the back surface (surface facing the back foil) of the top foil piece.
- 3C is a cross-sectional view taken along line 3C-3C in FIG. 3A.
- FIG. 3D is an explanatory diagram in which a plan view and a side view are associated with each other in order to explain the shape of the bump foil piece.
- the thrust bearings 3A (3) are disposed on both sides of the thrust collar 4, respectively.
- the pair of thrust bearings 3 ⁇ / b> A (3) has the same configuration, and is an annular (cylindrical) device disposed to face the disc-shaped thrust collar 4 fixed to the rotating shaft 1.
- the rotary shaft 1 is surrounded. Both surfaces of the thrust collar 4 (both surfaces in the axial direction of the rotary shaft 1) are configured as supported surfaces, and the pair of thrust bearings 3A (3) are supported so as to face both supported surfaces of the thrust collar 4, respectively.
- the thrust bearing 3A includes a top foil 10 disposed to face the thrust collar 4, and a back foil 20 disposed to face a surface of the top foil 10 opposite to the surface facing the thrust collar 4.
- the back foil 20 includes an annular plate-like base plate 30 disposed on the side opposite to the side closer to the top foil 10.
- a cylindrical bearing spacer 40 indicated by a two-dot chain line is sandwiched between the base plates 30 and 30 of the pair of thrust bearings 3A and 3A. They are connected via a spacer 40.
- 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 and 3A is fixed to the housing 5 by fastening bolts 41 with the thrust collar 4 sandwiched therebetween. ing.
- the base plate 30 is an annular plate-like metal member having a thickness of about several millimeters, and a plurality of through holes 42 for inserting the fastening bolts 41 into the outer periphery thereof (this embodiment). 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 facing the thrust collar 4.
- the back foil 20 has a plurality (six) of back foil pieces 21 and the top foil 10 has a plurality of (six) top foil pieces 11 as described later.
- the base plate 30 is formed with six support regions 31 whose surface is divided into six in the circumferential direction (equally divided into six).
- the six support regions 31 in the present embodiment are designed regions, and the surface of the base plate 30 including these support regions 31 is a uniform plane.
- the back foil piece 21 and the top foil piece 11 are arranged in this order in each support region 31 and supported by the support region 31.
- the base plate 30, the back foil piece 21, and the top foil piece 11 are stacked in the axial direction of the rotating shaft 1.
- 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 respectively arranged on a plurality of support regions 31 of the base plate 30, thereby being arranged in the circumferential direction of the base plate 30. Further, these back foil pieces 21 are formed slightly smaller in plan view than the top foil pieces 11 to be described later. Therefore, the top foil pieces 21 are not exposed to the thrust collar 4 on the base plate 30 as shown in FIG. 3A. Covered with a piece 11.
- 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).
- back foil 20 examples include a bump foil, a spring foil described in Japanese Patent Laid-Open No. 2006-57652, Japanese Patent Laid-Open No. 2004-270904, and Japanese Patent Laid-Open No. 2009-299748.
- the back foil etc. which are described in the gazette etc. are used.
- the spring foil described in Japanese Patent Laid-Open No. 2006-57652 and Japanese Patent Laid-Open No. 2004-270904 and the back foil described in Japanese Patent Laid-Open No. 2009-299748 are used for radial bearings.
- it is the foil used if these are developed in a flat shape and formed into an annular plate shape, it can be used for a thrust bearing.
- the back foil 20 is made of a bump foil, and therefore the back foil piece 21 is made of a bump foil piece.
- a back foil piece 21 (bump foil piece) has a foil (metal thin plate) having a thickness of several hundreds of ⁇ m formed into a corrugated shape by press molding, and the whole is substantially in plan view as shown in FIG. 3D. It is formed in a pentagon shape.
- the back foil piece 21 thus formed into a corrugated plate shape is formed by alternately arranging valley portions 22 that contact the base plate 30 and peak portions 23 that contact the top foil piece 11.
- the valley portions 22 and the mountain portions 23 are arranged in a direction orthogonal to the extending direction of an end side 11 a of the top foil piece 11 to be described later in plan view.
- the valley portion 22 and the mountain portion 23 are arranged in a direction intersecting with the extending direction of the fixed side 12 of the top foil piece 11. That is, the plurality of peak portions 23 are adjacent to each other in a direction intersecting the extending direction of the fixed side 12 in plan view.
- valley portions 22 and peak portions 23 are formed at substantially equal intervals. Further, the height of the peak portion 23 is constant from the fixed side 12 side toward the opposite side, that is, the downstream side in the rotational direction of the rotary shaft 1 (thrust collar 4) indicated by the arrow R in FIG. 3A. It is formed so as to increase in height (see FIG. 3C). Further, the back foil piece 21 substantially coincides with the end side 21a on the downstream side in the rotation direction of the rotating shaft 1 in a state viewed in plan view with the end side 11a on the downstream side in the rotation direction of the rotating shaft 1 in the top foil piece 11 described later. Placed in position. The back foil piece 21 is spot-welded (dot welded) to the base plate 30 and fixed along the direction of formation of the valley portion 22 that becomes the end side 21a.
- the end side 21a of the back 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 to the base plate 30. Therefore, the back 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. 3A.
- These top foil pieces 11 are circular plate shapes obtained by dividing an annular plate in the circumferential direction thereof, that is, a metal thin plate (foil) having a thickness of about several hundred ⁇ m, and a portion including the apex is cut from a sector shape. Except for this, it is an arc plate-like member in which the inner peripheral end (radial inner end) and the outer peripheral end (radial outer end) are arc-shaped.
- the top foil pieces 11 having such a shape are arranged on the respective support regions 31 of the base plate 30 so as to cover the back 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
- the top foil piece 11 is formed slightly smaller than the support region 31 in plan view and slightly larger than the back foil piece 21 in plan view. As a result, the plurality of top foil pieces 11 are arranged in the respective support regions 31 so as not to interfere with each other and without exposing the back foil pieces 21 to the thrust collar 4 so as to cover the upper surfaces thereof. .
- the present invention is not limited to this, and the top foil piece 11 may be formed in the same size as the back foil piece 21 in plan view, or may be formed smaller than the back foil piece 21 in plan view. Also good.
- the top foil piece 11 has a fixing portion 13 on the upstream side in the rotation direction of the rotating 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 21a of the back 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. In other words, the fixed portion 13 and the fixed side 12 of the present embodiment are arranged at substantially the same position, but the fixed side of the present invention is a side located on the downstream side of the rotating shaft 1 in the rotation direction of the rotating shaft 1. It is configured.
- the top foil piece 11 is bent in the vicinity of the fixed side 12 as shown in FIG. 3C, so that a height substantially equal to the height of the peak portion 23 of the back foil piece 21 can be secured.
- the portion closer to the end side 11 a than the fixed side 12 is placed on the peak portion 23.
- the end side 11a (trading edge) side is merely a free end supported on the peak portion 23 of the back foil piece 21 without being fixed to the base plate 30 or the like.
- the back foil piece 21 is arranged so that the valleys 22 and the crests 23 of the back foil piece 21 are arranged in a direction intersecting the fixed side 12 of the top foil piece 11. Therefore, these troughs 22 and crests 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 parallel to the end side 11a. Therefore, the top foil piece 11 is placed on the back foil piece 21 to gradually move the inner surface of the base plate 30 (from the fixed side 12 toward the end side 11 a along the arrangement direction of the peaks 23. It is arranged so as to be inclined at an initial inclination angle set by the peak portion 23 of the back foil piece 21 so as to be away from the surface on which the support region 31 is provided.
- 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.
- the inclination angle is an angle (gradient) ⁇ determined by the height increase amount of the peak portion 23 of the back foil piece 21 as shown in FIG. 3D.
- the inclination angle is an angle between the top foil piece 11 and the inner surface of the base plate 30. This inclination angle is equal to the angle between the top foil piece 11 and the supported surface of the thrust collar 4. Therefore, when the load increases, the peak portion 23 of the back foil piece 21 is pushed toward the base plate 30 and the entire back foil piece 21 is flattened, whereby the top foil piece 11 is also displaced toward the base plate 30 and is inclined.
- the angle ⁇ is smaller than the initial inclination angle.
- the top foil piece 11 has an end 11 a arranged in parallel with the extending direction of the valley portion 22 and the peak portion 23 of the back foil piece 21, and the back foil piece 21 has the peak portion 23.
- the arrangement direction is arranged orthogonal to the end side 11a. Therefore, the end side 11a which is the free end of the top foil piece 11 is applied with a load on the back foil piece 21 through the top foil piece 11 by the rotation of the thrust collar 4 even in the initial inclination angle state, and the inclination angle ⁇
- the height from the base plate 30 becomes substantially constant even when becomes smaller.
- the surface of the top foil piece 11 facing the back foil piece 21 is cut (removed) by etching or the like, and the fixed side 12 (fixing portion 13) of the top foil piece 11 as shown in FIG. 3B. And the vicinity thereof, that is, the fixed side 12 and the fixed part side thin part 14 (thin part) formed thinner than the other parts in the vicinity of the fixed side 12 and the vicinity located downstream of the fixed side 12 in the rotation direction of the rotary shaft 1. ) Is formed.
- fixed part side thin part 14 as long as a distortion etc. are not produced in the top foil piece 11, you may use electrolytic processing etc.
- the fixed portion side thin portion 14 is formed linearly along the length direction of the fixed side 12, that is, extends from the outer peripheral end to the inner peripheral end along the radial direction of the top foil piece 11. It is formed by etching or the like.
- the thickness of the fixed portion side thin portion 14 is preferably about 50% to 70% of the thickness of the portion of the top foil piece 11 that is not etched by etching (about several hundred ⁇ m). By forming the fixed portion side thin portion 14 with such a thickness, the downstream portion of the rotating shaft 1 can be more easily displaced.
- the fixed portion side thin portion 14 is formed so as not to 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. 3C. ing. That is, the fixed portion side thin portion 14 includes the fixed side 12 and the width is set and formed so as to be positioned between the fixed side 12 and the apex (ridge line) of the peak portion 23 closest to the fixed side 12. Yes. As a result, the top foil piece 11 is placed on all the crests 23 except for the fixed part-side thin part 14 and is evenly supported by them, so that the inclination angle ⁇ shown in FIG. 3D is maintained.
- the fixed portion side thin portion 14 by forming the fixed portion side thin portion 14, the portion closer to the end side 11a than the fixed portion side thin portion 14 can be displaced more easily and smoothly (its inclination angle is easily changed). Furthermore, since the top foil piece 11 can be easily rotated by forming such a fixed portion side thin portion 14, the thickness of portions other than the fixed portion side thin portion 14 is thicker than in the prior art. It is also possible to do.
- the thrust bearing 3A is provided on both sides of the thrust collar 4 as shown in FIG.
- the thrust bearings 3A are provided on both sides of the thrust collar 4 as shown in FIG.
- both thrust bearings 3A are installed close to the thrust collar 4 so that a large gap does not occur.
- the top foil pieces 11 (top foils 10) of the thrust bearings 3A are slightly pressed against the thrust collar 4.
- the portion near the end side 11a is easily inclined (displaceable). Therefore, the pressing force generated as compared with the pressing amount is small, and thereby the starting torque of the rotating shaft 1 is small.
- an inclination angle larger than the optimum angle is previously provided so that the inclination angle of the top foil piece becomes the optimum angle when the load applied to the bearing increases. Accordingly, when the rotation is stopped, the top foil piece is in a state where the thrust collar 4 is sandwiched from both sides and pressed (preloaded state). However, conventionally, since the thickness of the top foil piece is constant, the pressing force (preload) to the thrust collar 4 is strong, and the starting torque of the rotating shaft 1 may be increased. On the other hand, in this embodiment, since the fixed part side thin part 14 is formed in the top foil piece 11 as described above, the starting torque is reduced.
- the top foil piece 11 When a thrust load is applied, the top foil piece 11 is further pushed to the back foil piece 21, and the inclination angle ⁇ of the top foil piece 11 becomes small. At this time, the top foil piece 11 rotates (bends) around the fixed side 12 on the upstream side in the rotation direction of the rotary shaft 1, so that the fixed portion-side thin portion 14 causes the rotary shaft 1 on the downstream side in the rotational direction. The portion near the side 11a is easily and smoothly displaced. Therefore, even if the thrust load is further increased and the thickness of the fluid lubricating film is further reduced, the top foil piece 11 is difficult to contact the thrust collar 4 and an optimum inclination angle is easily obtained.
- the fixed portion side thin portion 14 is formed in the vicinity of the fixed side 12 and the downstream side in the rotation direction of the top foil piece 11, so that the load is reduced.
- the portion near the end 11a can be displaced more easily and smoothly, so that the starting torque of the rotating shaft 1 is reduced.
- the top foil piece 11 easily and smoothly rotates around the fixed portion side thin portion 14, so that the optimum inclination angle of the top foil piece 11 is easily obtained.
- the bearing load capacity is improved.
- the top foil piece 11 Since the pressure of the fluid lubrication film is increased when receiving a high thrust load, the top foil piece 11 is not directly supported by the back foil piece 21, that is, a portion located on the valley portion 22 of the back foil piece 21. There is a possibility that the pressure will escape from here and the load capacity will be reduced.
- the fixed portion side thin portion 14 is formed on the fixed side 12 (the fixed side 12 and the vicinity thereof) of the top foil piece 11, the movement of the top foil piece 11 being displaced (bent) is prevented.
- FIG. 4A is a plan view showing the back surface of the top foil piece 50.
- 4B is a cross-sectional view taken along line 4B-4B in FIG. 4A.
- FIG. 4C is an explanatory diagram of a valley-side thin portion.
- the top foil piece 50 shown in FIGS. 4A to 4C is different from the top foil piece 11 shown in FIGS. 3A to 3D in that the crest portion 23 is located at a position facing the valley portion 22 of the back foil piece 21 shown in FIG. 3D. It is that the valley side thin part 16 (thin part) formed thinner than the part opposite to is formed. Since a plurality of valley portions 22 are provided, a plurality of valley side thin portions 16 are also formed.
- the valley portion side thin portion 16 is formed in a groove shape extending from the outer peripheral end of the top foil piece 50 to the inner peripheral end or the side end, and is formed by etching or the like in the same manner as the fixed portion side thin portion 14. Yes.
- the side end is an edge portion on one side in the circumferential direction of the top foil piece 50.
- several valley-side thin portions 16 (three in the present embodiment) extend from the outer peripheral end of the top foil piece 50 to the inner peripheral end,
- the other trough side thin part 16 (three in this embodiment) is extended from the outer peripheral end of the top foil piece 50 to the side end (refer FIG. 4A).
- the valley side thin portion 16 is preferably made as thin as the fixed portion side thin portion 14. Therefore, in the present embodiment, the plate material of the top foil piece 50 is etched once to form the fixed portion side thin portion 14 and the valley portion thin portion 16 at the same time.
- the valley-side thin portion 16 may be formed to have a different thickness from the fixed portion-side thin portion 14, and in that case, etching processing for forming the fixed portion-side thin portion 14 and the valley-side thin portion are performed. Etching for forming 16 is performed separately.
- the above-mentioned “location facing the valley 22 of the back foil piece 21” is defined as follows, for example. That is, as shown in FIG. 4C, the peak of the peak portion 23 of the back foil piece 21 is H, and the position adjacent to the valley portion 22 of the peak portion 23, that is, the boundary line (connection portion) between the peak portion 23 and the valley portion 22. And L, and the intermediate point on the base plate 30 between the vertex H and the boundary line L is M, the top foil piece 50 corresponding to the vertical direction between the two intermediate points M and M across the valley portion 22. These locations are locations facing the valleys 22. Therefore, as shown in FIG. 4C, the valley side thin portion 16 is formed at a location corresponding to the intermediate point M between the top foil pieces 50.
- 4C shows the case where the valley portion 22 has a width, when the valley portion 22 is simply a bent portion and does not have a width, the boundary portion L is adjacent to the mountain portion. 23 and 23 only become common (the boundary line L becomes a connecting portion between the adjacent peak portions 23 and 23), and the above definition can be used as it is.
- the fixed portion side thin portion 14 is formed as in the first embodiment, it is possible to increase the plate thickness of the plate material constituting the top foil piece 50 as compared with the prior art. is there.
- the pressure of the fluid lubrication film acts on the top foil piece 50, it becomes easy to bend toward the back foil 20 at the radial central portion sandwiched between the inner peripheral end and the outer peripheral end of the top foil piece 50.
- the pressure of the fluid lubricating film in the central portion may decrease, and the load capacity of the bearing may be reduced.
- the top foil piece 50 is easily bent from the upstream side to the downstream side in the rotation direction of the rotating shaft 1, that is, in the circumferential direction (the surface of the top foil piece 50.
- the top foil piece 50 is easily bent from the upstream side to the downstream side in the rotation direction of the rotating shaft 1, that is, in the circumferential direction (the surface of the top foil piece 50.
- the radial direction difficult to bend in the radial direction (bending rigidity) (difficult to bend around the axis parallel to the surface of the top foil piece 50 and perpendicular to the radial direction) ) Is maintained at the same bending difficulty as before the formation of the valley side thin portion 16.
- the bending direction is less likely to bend in the radial direction while maintaining the ease of bending in the circumferential direction.
- the bending toward the back foil 20 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
- FIG. 5A 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 line AA in the plan view) are associated with each other.
- 5B is a cross-sectional view taken along line 5B-5B in FIG. 5A.
- the top foil piece 60 shown in FIGS. 5A and 5B is different from the top foil piece 50 shown in FIGS. 4A to 4C in that the surface facing the back foil piece 21 is cut (removed) by etching or the like. Accordingly, as shown in FIG. 5A with shading, the inner peripheral end side thin portion 15 formed thinner than the outer peripheral end side is formed on the inner peripheral end side. However, in this embodiment, the inner peripheral end side thin part 15 is formed at a position avoiding the valley part thin part 16, that is, between the adjacent valley part thin parts 16, 16.
- the “inner peripheral end side” indicates a portion near the inner peripheral end (or a portion including the inner peripheral end) in the top foil piece 60
- the “outer peripheral end side” indicates a portion near the outer peripheral end in the top foil piece 60. (Or a part including the outer peripheral edge).
- the top foil piece 60 is more easily bent on the inner peripheral end side than on the outer peripheral end side.
- the boundary line 15a between the inner peripheral end side thin portion 15 and the outer peripheral end side thereof, that is, the stepped portion has an arc shape along the circumferential direction of the inner peripheral end or outer peripheral end of the top foil piece 60.
- the width W1 of the inner peripheral end side thin portion 15 in the radial direction of the top foil piece 60 is 1 ⁇ 2 or less of the radial width W2 of the top foil piece 60 as a whole. It is preferable that the outer peripheral end side of the top foil piece 60 can function in the same manner as the conventional one while suppressing the rising toward the thrust collar 4 on the inner peripheral end side of the piece 60. In addition, it is preferable that the width W1 is 1/8 or more of the width W2 in order to surely suppress the rising toward the thrust collar 4 on the inner peripheral end side of the top foil piece 60.
- the shaving amount of the inner peripheral end side thin portion 15, that is, the difference in thickness between the inner peripheral end side thin portion 15 and the outer peripheral end side may be about 10 to 20 ⁇ m.
- the top foil piece 60 is shaved with such an amount, and the inner peripheral end side thin portion 15 is formed about 10 to 20 ⁇ m thinner than the portion on the outer peripheral end side excluding the fixed portion side thin portion 14 and the valley portion thin portion 16.
- a gap corresponding to this difference can be formed between the apex of the peak portion 23 of the back foil piece 21.
- This gap affects the fluid lubrication film formed between the thrust collar 4 and the top foil piece 60. Since this fluid lubrication film is also sufficiently thin, the gap functions sufficiently even at about 10 to 20 ⁇ m. Further, with this amount of cutting, it is possible to satisfactorily suppress the rising of the inner peripheral end toward the thrust collar 4 without making the inner peripheral end of the top foil piece 60 extremely easy to bend. .
- the inner peripheral end side thin portion 15 is also formed by etching or the like in the same manner as the fixed portion side thin portion 14 and the valley portion thin portion 16. However, as described above, it is preferable that the fixed portion side thin portion 14 and the valley portion thin portion 16 have the same thickness, and the inner peripheral end side thin portion 15 has the fixed portion side thin portion 14 and the valley portion side. Since it is preferable to reduce the amount of cutting as compared with the thin portion 16, the etching process is performed twice on the plate material of the top foil piece 60 in this embodiment. For example, the valley-side thin portion 16 and the fixed portion-side thin portion 14 are formed by the same etching process, and then the inner peripheral end-side thin portion 15 is formed by a separate etching process. When forming the inner peripheral end side thin portion 15, the portion where the valley portion thin portion 16 is formed is not subjected to etching, and is selectively etched only at a position avoiding the valley portion thin portion 16. Like that.
- the top foil piece 60 is pushed toward the back foil piece 21, and the inclination of the top foil piece 60 is performed.
- the angle ⁇ becomes smaller.
- 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.
- the pressure membrane pressure
- the inner peripheral end side thin portion 15 is formed on the inner peripheral end side of the top foil piece 60, the inner peripheral end side is more easily bent than the outer peripheral end side. Further, since a gap is formed between the inner peripheral end side thin portion 15 and the back foil piece 21 (bump foil piece) on the inner peripheral end side, the inner peripheral end side is pushed into the back foil piece 21. It is easy. At this time, a force to push back the top foil piece 60 toward the thrust collar 4 by the back foil piece 21 is less likely to be generated on the inner peripheral end side by the gap.
- the inner peripheral end side tends to rise toward the thrust collar 4 because the peripheral speed of the thrust collar 4 on the inner peripheral end side of the thrust bearing is slower than the peripheral speed on the outer peripheral end side. The That is, the inner peripheral end side is difficult to get up toward the thrust collar 4.
- the elastic force (back foil piece 21) of the back foil piece 21 is equivalent to the gap as compared with the outer peripheral end side. Since the reaction force received by the top foil piece 60 is weakened, the inner peripheral end side is difficult to get up toward the thrust collar 4 as described above. Therefore, even if the thrust load is further increased and the thickness of the fluid lubrication film is further reduced, the top foil piece 60 is less likely to contact the thrust collar 4, and as a result, a higher thrust load can be supported. .
- the inner peripheral end side thin portion 15 that is thinner than the outer peripheral end side is formed on the inner peripheral end side of the top foil piece 60, and the inner peripheral end side is easily bent. Since a gap is formed between the back foil piece 21 on the peripheral end side, it is difficult to generate a force by which the top foil piece 60 is pushed back to the thrust collar 4 side by the back foil piece 21 on the inner peripheral end side. it can. Therefore, it is possible to prevent the inner peripheral end side from being easily raised toward the thrust collar 4 due to the peripheral speed of the thrust collar 4 on the inner peripheral end side being slower than the peripheral speed on the outer peripheral end side.
- the fixed portion side thin portion 14, the inner peripheral end side thin portion 15 and the valley portion thin portion 16 are all formed, but the present invention is not limited to this, and the top of the first embodiment. You may form the inner peripheral end side thin part 15 of this embodiment in the foil piece 11. FIG. Further, only the inner peripheral end side thin portion 15 of the present embodiment and the valley side thin portion 16 of the second embodiment may be formed on the top foil piece.
- FIG. 6A is a plan view of the thrust bearing 3 partially in cross section.
- FIG. 6B is an explanatory diagram in which a plan view showing the back surface and a side view are associated with each other in order to explain the configuration of the top foil piece 50.
- 6C is a cross-sectional view taken along line 6C-6C in FIG. 6A.
- FIG. 6D is an explanatory diagram in which the plan view and the side view are associated with each other in order to explain the shape of the bump foil piece.
- the entire region supporting the back foil piece 21 and the top foil piece 50 used in the second embodiment in the support region 31 is arranged on the fixed side 12 side of the top foil piece 50. It is set as the inclined surface 32 from which height increases as it goes to the edge 50a side of a downstream side. That is, the inclined surface 32 is formed to be inclined in a direction orthogonal to the end side 50a as shown in FIG. 6C.
- the back foil piece 21 is formed in a corrugated plate shape in which trough portions 22 in contact with the base plate 30 and crest portions 23 in contact with the top foil pieces 50 are alternately arranged as in the first embodiment. .
- the heights of the peak portions 23 are all formed to be the same.
- the valley portion 22 and the mountain portion 23 are arranged in a direction intersecting with the fixed side 12 of the top foil piece 50 in plan view as in the above embodiment. That is, the arrangement direction of the valley portion 22 and the mountain portion 23 is set to a direction intersecting with the fixed side 12, and coincides with the inclination direction of the inclined surface 32.
- the peak portion 23 of the back foil piece 21 has a predetermined height as the position of the apex extends 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, the position of the apex of the peak portion 23 is apparently the same as that of the first embodiment or the second embodiment.
- the top foil piece 50 disposed on the back foil piece 21 is formed in the same manner as the first embodiment in the inclination angle ⁇ .
- the inclination angle ⁇ of the top foil piece 50 is determined by the inclination angle ⁇ of the inclined surface 32 as shown in FIG. 6D.
- the fixed portion side thin portion 14 is formed on the top foil piece 50 as shown in FIG. 6B, when the load is applied, it is closer to the end side 50a. The portion can be displaced more easily and smoothly. Therefore, the optimum inclination angle of the top foil piece 50 can be easily obtained even after the rotating shaft 1 starts to rotate, and the load capacity of the bearing is improved.
- the valley-side thin portion 16 is formed, the same ease of bending in the circumferential direction is maintained in the circumferential direction by using a thicker plate material than in the past to form the top foil piece 50.
- both the fixed part side thin part 14 and the trough part thin part 16 are formed, it is not limited to this, One of the fixed part side thin part 14 and the trough part thin part 16 You may combine the top foil piece in which this was formed with the base plate 30 of this embodiment which has the inclined surface 32. FIG. Moreover, you may form the inner peripheral end side thin part 15 of 3rd Embodiment in the top foil piece 50 of this embodiment.
- the back foil 20 and the top foil 10 are each composed of six back foil pieces 21 (bump foil pieces) and top foil pieces 11, and accordingly, six support regions 31 of the base plate 30 are formed accordingly. (Setting).
- the number of the back foil pieces 21 (bump foil pieces) and the top foil pieces 11 may be 5 or less or 7 or more as long as it is plural. In that case, the number of support regions 31 is also adjusted in accordance with the number of back foil pieces 21 (bump foil pieces) and top foil pieces 11.
- top foil piece used for this invention the structure which eliminated the fixing
- the top foil piece 50 of the second embodiment is used as the top foil piece.
- the top foil piece 11 of the first embodiment or the top of the third embodiment is used instead.
- a foil piece 60 can also be used.
- the entire surface on which the back foil piece 21 is placed is changed to the inclined surface 32, and the inclined surface and the flat surface ( A surface parallel to the supported surface of the thrust collar 4 may be formed, and a part of the back foil piece 21 may be disposed on the inclined surface and the remaining part may be disposed on the flat surface.
- the flat surface may be formed on the upper side of the inclined surface (position closer to the end side 11a, position closer to the thrust collar 4), or may be formed on the lower side (position closer to the fixed side 12).
- flat surfaces may be formed on both sides of the inclined surface in the circumferential direction.
- the present invention can be used for a thrust bearing that is disposed to face a thrust collar provided on a rotating shaft and supports the thrust collar.
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Abstract
Description
本願は、2013年9月19日に日本に出願された特願2013-194441号に基づき優先権を主張し、その内容をここに援用する。
本発明の第2の態様によれば、薄肉部が、固定部およびこの固定部の近傍部でこの固定部より前記回転軸の回転方向下流側に形成された、トップフォイル片の外周端から内周端にまで延びる固定部側薄肉部を含んでいる。このため、前記したようにトップフォイル片を形成するために従来に比べて厚い板材を用いることにより、特に径方向で従来より曲がり難くして中央部でのバックフォイルに向かう撓みを抑制することができる。
また、固定部側薄肉部によってトップフォイル片における回転軸の回転方向下流側の部分が容易にかつ円滑に変位できるようになり、したがって、例えばスラストカラーが一対のトップフォイルによって挟み込まれているような場合に、回転軸の始動トルクが低減する。また、回転軸が回転を開始した後も、トップフォイル片が容易にかつ円滑に変位するため、トップフォイル片の最適傾斜角が得られ易くなり、軸受の負荷能力が向上する。
本発明の第3の態様によれば、薄肉部が谷部側薄肉部を含んでいるので、前記したようにトップフォイル片を形成するために従来に比べて厚い板材を用いることにより、特に径方向で従来より曲がり難くして中央部でのバックフォイルに向かう撓みを抑制することができる。また、回転軸の回転方向上流側から下流側にかけて、すなわち周方向においては、谷部側薄肉部によってトップフォイル片が曲がり易くなるので、トップフォイル片の傾斜角が容易に最適角となり、軸受の負荷能力が高まる。
この第4の態様によれば、バンプフォイル片によってトップフォイル片を弾性的に支持することができる。また、高さが変化しているバンプフォイル片の山部に応じて、トップフォイル片の高さを変化させることができる。
この第5の態様によれば、この傾斜面上にバックフォイル片を介してトップフォイル片を配設することにより、トップフォイル片の高さを傾斜面に沿って精度よく変化させることができる。また、その際にバックフォイル片については、高さを変化させることなく一定の高さに作製すればよく、したがって加工コストを抑えることができる。
この第6の態様によれば、バンプフォイル片によってトップフォイル片を弾性的に支持することができる。また、バンプフォイルの下流側端辺に最も近い山部の稜線をスラストカラーの被支持面と平行にできるため、この山部に支持されるトップフォイルの下流側端辺とスラストカラーとを常に平行にし易くなる。
この第7の態様によれば、トップフォイル片に発生する流体潤滑膜の圧力が軸受隙間の狭い側、すなわち回転軸の回転方向下流側で高くなるようにするべく、トップフォイル片の回転方向下流側を高い剛性で支持することができ、これによって軸受の負荷能力を高めることができる。
図1は、本発明のスラスト軸受が適用されるターボ機械の一例を模式的に示す側面図であり、図1中符号1は回転軸、符号2は回転軸の先端部に設けられたインペラ、符号3は本発明に係るスラスト軸受を示している。
また、インペラ2は静止側となるハウジング5内に配置されており、インペラ2とハウジング5との間にチップクリアランス6が形成されている。
また、回転軸1には、スラストカラー4より中央寄りの部分に、ラジアル軸受7が設けられている。
本実施形態では、一対のスラスト軸受3A、3Aの、それぞれのベースプレート30、30間に、二点鎖線で示す円筒状の軸受スペーサ40が挟持されており、ベースプレート30、30は締結ボルト41によって軸受スペーサ40を介して連結されている。また、一方のベースプレート30は、その外面が締結ボルト41によってハウジング5に固定されており、したがって一対のスラスト軸受3A、3Aは、スラストカラー4を挟んだ状態で締結ボルト41によってハウジング5に固定されている。
図3A,3C,3Dに示すようにバックフォイル20は、ベースプレート30の周方向に配列された6枚のバックフォイル片21によって形成されている。これらバックフォイル片21は、ベースプレート30の複数の支持領域31上にそれぞれ配置され、これによってベースプレート30の周方向に配列されている。また、これらバックフォイル片21は、後述するトップフォイル片11より平面視で僅かに小さく形成され、したがって図3Aに示すようにベースプレート30上にてスラストカラー4に対して露出することなく、トップフォイル片11に覆われている。
また、バックフォイル片21は、回転軸1の回転方向下流側の端辺21aが、後述するトップフォイル片11における回転軸1の回転方向下流側の端辺11aと平面視した状態でほぼ一致する位置に配置されている。バックフォイル片21は、この端辺21aとなる谷部22の形成方向に沿って、ベースプレート30にスポット溶接(点付溶接)され、固定されている。
なお、ベースプレート30への端辺21aの固定については、スポット溶接以外にも、例えばネジ止めなどによって行うことができる。
このような形状のトップフォイル片11は、ベースプレート30の各支持領域31上にて前記バックフォイル片21を覆ってそれぞれ配置され、ベースプレート30の周方向に等間隔で配列されて全体として略円環板状に配置されたことにより、トップフォイル10を形成している。
一方、端辺11a(トレーディングエッジ)側は、ベースプレート30等に固定されることなく単にバックフォイル片21の山部23上に支持された自由端となっている。
本実施形態では、図2に示したようにスラスト軸受3Aをスラストカラー4の両側に設けている。このようにスラストカラー4の両側にスラスト軸受3Aを設けることにより、スラスト方向におけるスラストカラー4(回転軸1)の移動量を極力抑えることができる。すなわち、スラスト移動量を小さくすることにより、図1に示したチップクリアランス6を狭くした場合でもインペラ2等のハウジング5への接触を防止することができ、チップクリアランス6を狭くすることでターボ機械等のターボ機械としての流体性能を向上させることができる。
これに対して本実施形態では、前記したようにトップフォイル片11に固定部側薄肉部14を形成しているため、始動トルクが小さくなる。
したがって、このようにトップフォイル片11の板厚を厚くことにより、バックフォイル片21に支えられていない部分での撓みを少なくすることができ、負荷能力の低下を抑制することができる。
第2実施形態のスラスト軸受が第1実施形態のスラスト軸受3A(3)と主に異なるところは、トップフォイル片として、図4A~4Cに示す構成を用いた点である。図4Aはトップフォイル片50の裏面を示す平面図である。図4Bは図4Aの4B-4B線矢視断面図である。図4Cは谷部側薄肉部の説明図である。
ただし、谷部側薄肉部16を固定部側薄肉部14とは異なる薄さに形成してもよく、その場合には、固定部側薄肉部14形成のためのエッチング加工と谷部側薄肉部16形成のためのエッチング加工とを別に行う。
すなわち、図4Cに示すようにバックフォイル片21の山部23の頂点をHとし、山部23の谷部22と隣接する位置、つまり山部23と谷部22との境界線(接続部)をLとし、さらに頂点Hと境界線Lとのベースプレート30上での中間点をMとすると、谷部22を挟んだ二つの中間点M、M間に紙面上下方向で相当するトップフォイル片50の箇所を、谷部22に対向する箇所とする。したがって、図4Cに示すようにトップフォイル片50の中間点M、M間に対応する箇所に、谷部側薄肉部16を形成する。なお、図4Cでは谷部22が幅を有している場合について示したが、谷部22が単に折り曲げ部であり、幅を有していない場合には、前記境界線Lが隣り合う山部23、23間で共通になるだけで(境界線Lは隣り合う山部23、23の接続部となる)、前記した定義はそのまま用いることができる。
流体潤滑膜の圧力がトップフォイル片50に作用すると、トップフォイル片50の内周端と外周端に挟まれた径方向の中央部では、バックフォイル20に向けて撓み易くなる。このような撓みが大きくなると、前記中央部において流体潤滑膜の圧力が低下し、軸受の負荷能力が低くなる場合がある。
よって、本実施形態では、径方向中央部での撓みを抑制することにより、同部位において流体潤滑膜の圧力が低下して負荷能力が低くなることを抑制することができる。
第3実施形態のスラスト軸受が第2実施形態のスラスト軸受と主に異なるところは、トップフォイル片として、図5A,5Bに示す構成を用いた点である。図5Aはトップフォイル片60の裏面を示す平面図と側面図(前記平面図のA-A線矢視断面図)とを対応させた説明図である。図5Bは図5Aの5B-5B線矢視断面図である。
本実施形態では、この内周端側薄肉部15とその外周端側との境界線15a、すなわち段差部は、トップフォイル片60の内周端や外周端の周方向に沿う円弧状になっている。
よって、スラスト荷重がさらに増して流体潤滑膜の膜厚がさらに薄くなったとしても、トップフォイル片60はスラストカラー4に接触し難くなり、結果としてより高いスラスト荷重を支持することが可能になる。
なお、本実施形態では、固定部側薄肉部14、内周端側薄肉部15、及び谷部側薄肉部16をいずれも形成しているが、これに限定されず、第1実施形態のトップフォイル片11に本実施形態の内周端側薄肉部15を形成してもよい。また、本実施形態の内周端側薄肉部15及び第2実施形態の谷部側薄肉部16のみがトップフォイル片に形成されていてもよい。
第4実施形態のスラスト軸受3B(3)が第2実施形態のスラスト軸受と主に異なるところは、図6A~6Dに示すように、ベースプレート30の前記支持領域31に傾斜面32を形成した点と、バックフォイル片21の山部23の高さを、全て同一にした点である。なお、図6Aは一部を断面視したスラスト軸受3の平面図である。図6Bはトップフォイル片50の構成を説明するためにその裏面を示す平面図と側面図とを対応させた説明図である。図6Cは図6Aの6C-6C線矢視断面図である。図6Dはバンプフォイル片の形状を説明するためにその平面図と側面図とを対応させた説明図である。
また、谷部側薄肉部16を形成しているので、トップフォイル片50を形成するために従来に比べて厚い板材を用いることにより、周方向においては従来と同様の曲がり易さを維持しつつ、径方向では従来より曲がり難くして中央部でのバックフォイル20に向かう撓みを抑制することができる。よって、径方向中央部において流体潤滑膜の圧力が低下して負荷能力が低くなることを抑制することができる。
なお、本実施形態では、固定部側薄肉部14及び谷部側薄肉部16をいずれも形成しているが、これに限定されず、固定部側薄肉部14及び谷部側薄肉部16の一方を形成したトップフォイル片を、傾斜面32を有する本実施形態のベースプレート30に組み合わせてもよい。また、本実施形態のトップフォイル片50に、第3実施形態の内周端側薄肉部15を形成してもよい。
例えば、前記実施形態ではバックフォイル20やトップフォイル10をそれぞれ6つのバックフォイル片21(バンプフォイル片)、トップフォイル片11で構成し、したがってベースプレート30の支持領域31もこれに合わせて6つ形成(設定)している。しかし、バックフォイル片21(バンプフォイル片)やトップフォイル片11は、複数であれば5つ以下でも7つ以上であってもよい。その場合に、支持領域31の数についても、バックフォイル片21(バンプフォイル片)やトップフォイル片11の数に合わせて調整する。
また、前記第4実施形態では、トップフォイル片として第2実施形態のトップフォイル片50を用いているが、これに代えて、第1実施形態のトップフォイル片11、あるいは第3実施形態のトップフォイル片60を用いることもできる。
3,3A,3B スラスト軸受
4 スラストカラー
10 トップフォイル
11,50,60 トップフォイル片
11a 端辺
12 固定辺
13 固定部
14 固定部側薄肉部(薄肉部)
15 内周端側薄肉部
16 谷部側薄肉部(薄肉部)
20 バックフォイル
21 バックフォイル片(バンプフォイル片)
21a 端辺
22 谷部
23 山部
30 ベースプレート
31 支持領域
32 傾斜面
Claims (7)
- 回転軸に設けられたスラストカラーに対向して配置されるスラスト軸受であって、
前記スラストカラーに対向して配置されるトップフォイルと、
前記トップフォイルの、前記スラストカラーに対向する面と反対側の面に対向して配置されて、前記トップフォイルを支持するバックフォイルと、
前記バックフォイルの、前記トップフォイル寄りの側と反対の側に配置されて、前記バックフォイルを支持する円環板状のベースプレートと、を備え、
前記バックフォイルは、前記ベースプレートの周方向に配列された複数のバックフォイル片を有し、
前記トップフォイルは、前記複数のバックフォイル片の上にそれぞれ配設された複数のトップフォイル片を有し、
前記トップフォイル片には、前記回転軸の回転方向上流側に、前記ベースプレートに固定される固定部が形成されるとともに、前記バックフォイル片に対向する面が取り除かれてなる、前記トップフォイル片の外周端から内周端あるいは側端にまで延びる薄肉部が形成されているスラスト軸受。 - 前記薄肉部は、前記固定部および前記固定部の近傍部で前記固定部より前記回転軸の回転方向下流側に形成された、前記トップフォイル片の外周端から内周端にまで延びる固定部側薄肉部を含む請求項1に記載のスラスト軸受。
- 前記固定部は、前記回転軸の回転方向下流側に位置する直線状の固定辺を含んでおり、
前記バックフォイル片は、山部と谷部とを交互に形成した波板状のバンプフォイル片によって形成されるとともに、前記山部の配列方向が前記固定辺と交差して配置され、
前記薄肉部は、前記谷部に対向する箇所に形成された、前記山部に対向する箇所に比べて薄肉に形成された谷部側薄肉部を含む請求項1又は2に記載のスラスト軸受。 - 前記山部は、その高さが前記固定辺側から前記回転軸の回転方向下流側に向かうに連れて高くなるように形成されている請求項3に記載のスラスト軸受。
- 前記ベースプレートには、前記バックフォイル片を支持する各支持領域に、前記トップフォイル片の前記固定辺側から前記回転軸の回転方向下流側の端辺側に向かうに連れて高さが増加する傾斜面が形成されている請求項1~3のいずれか一項に記載のスラスト軸受。
- 前記バックフォイル片は、山部と谷部とを交互に形成した波板状のバンプフォイル片によって形成されるとともに、前記山部の配列方向が前記傾斜面の傾斜方向に一致するように配置されている請求項5に記載のスラスト軸受。
- 前記バンプフォイル片は、前記回転軸の回転方向下流側の端辺で前記ベースプレートに固定されている請求項3,4又は6に記載のスラスト軸受。
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CN201480051024.8A CN105683598B (zh) | 2013-09-19 | 2014-09-17 | 推力轴承 |
CA2924429A CA2924429C (en) | 2013-09-19 | 2014-09-17 | Thrust bearing |
EP14846602.2A EP3048317B1 (en) | 2013-09-19 | 2014-09-17 | Thrust bearing |
US15/070,258 US9903411B2 (en) | 2013-09-19 | 2016-03-15 | Thrust bearing |
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Also Published As
Publication number | Publication date |
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CN105683598B (zh) | 2018-06-15 |
US9903411B2 (en) | 2018-02-27 |
EP3048317A4 (en) | 2017-05-10 |
JP6372062B2 (ja) | 2018-08-15 |
CN105683598A (zh) | 2016-06-15 |
EP3048317B1 (en) | 2019-03-20 |
US20160195128A1 (en) | 2016-07-07 |
KR101903865B1 (ko) | 2018-10-02 |
KR20160054591A (ko) | 2016-05-16 |
EP3048317A1 (en) | 2016-07-27 |
CA2924429A1 (en) | 2015-03-26 |
JP2015059630A (ja) | 2015-03-30 |
CA2924429C (en) | 2017-12-12 |
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