A DAMPENED BEARING COMPONENT, BEARING INCLUDING SAID COMPONENT, AND ROTARY MACHINE INCLUDING SAID BEARING

Abstract

The bearing component comprises an external cylindrical member having an outer bearing surface and an inner cavity, and internal cylindrical member, arranged in the inner cavity of the external cylindrical member and substantially coaxial thereto. The external cylindrical member and the internal cylindrical member form a gap therebetween. A resilient damping feature is arranged in the gap.

Claims

1. A bearing component comprising: an external cylindrical member having an outer bearing surface and an inner cavity; an internal cylindrical member, arranged in the inner cavity of the external cylindrical member and substantially coaxial thereto; wherein the external cylindrical member and the internal cylindrical member form a gap therebetween; and wherein a resilient damping feature is arranged in the gap.

2. The bearing component of claim 1, wherein the resilient damping feature is adapted to allow at least one of a dampened radial displacements and dampened tangential displacements of the external cylindrical member with respect to the internal cylindrical member.

3. The bearing component of claim 1, further comprising bearing pads on the outer bearing surface of the external cylindrical member.

4. The bearing component of claim 3, wherein the bearing pads are polycrystalline diamond pads.

5. The bearing component of claim 1, wherein the resilient damping feature includes a corrugated tubular sheet arranged in the gap between the external cylindrical member and the internal cylindrical member.

6. The bearing component of claim 5, wherein the corrugated tubular sheet is made of metal.

7. The bearing component of claim 5, wherein the corrugated tubular sheet comprises corrugations extending parallel to an axis of the external cylindrical member and of the internal cylindrical member.

8. The bearing component of claim 7, further comprising displacement limiting devices, adapted to limit the displacement of the external cylindrical member and of the internal cylindrical member, one with respect to the other.

9. The bearing component of claim 7, wherein: the inner cavity of the external cylindrical member has first radial projections extending inwardly from a surface of the inner cavity towards the corrugated tubular sheet; the internal cylindrical member has second radial projections extending outwardly towards the external cylindrical member; the first radial projections and the second radial projections co-acting with the corrugations of the corrugated tubular sheet to limit angular displacements of the external cylindrical member with respect to the internal cylindrical member.

10. The bearing component of claim 1, wherein the resilient damping feature includes one of: a set of annular resilient damping members arranged around an axis of the external cylindrical member and internal cylindrical member, distanced from one another along said axis; a set of linear resilient damping members extending in a direction parallel to the axis of the external cylindrical member and internal cylindrical member and distanced from one another around said axis.

11. The bearing component of claim 1, wherein the gap is filled with a liquid, preferably with a lubricant liquid.

12. A bearing comprising an inner bearing component according to claim 1, and an outer bearing component, said outer bearing component and said inner bearing component being arranged coaxially to one another and adapted to rotate one with respect to the other around an axis of the bearing.

13. The bearing of claim 12, wherein the outer bearing component has an inner cylindrical bearing surface provided with a plurality of bearing pads co-acting with bearing pads on the outer bearing surface of the inner bearing component.

14. A rotary machine comprising a stationary shaft and a rotor supported for rotation on the stationary shaft; wherein the rotor is supported on the stationary shaft by at least one bearing according to claim 12.

15. A rotodynamic pump comprising a casing, a stationary shaft arranged in the casing and at least one rotary impeller arranged for rotation on the stationary shaft by at least one bearing according to claim 12.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A more complete appreciation of the disclosed embodiments of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

[0013] FIG. 1 shows a cross-sectional view of a multi-stage rotodynamic pump including embedded electric motors to drive the pump impellers;

[0014] FIG. 2 shows an enlargement of the bearing of one impeller of the pump of FIG. 1 and relevant lubrication circuit;

[0015] FIG. 3 shows a schematic cross-sectional view of an internal bearing component according to line of FIG. 2;

[0016] FIG. 4 shows a schematic cross-sectional view of a second embodiment of a bearing according to the present disclosure;

[0017] FIG. 5 shows a cross-sectional view according to line V-V of FIG. 4; and

[0018] FIG. 6 shows a schematic cross-sectional view of a third embodiment of a bearing according to the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

[0019] A novel and useful bearing structure has been developed, to improve the dynamic behavior of bearings, such as in particular, but not exclusively, PCD bearings and other bearings characterized by high stiffness. The novel bearings include two components, arranged coaxial to one another. One component rotates integrally with a rotary machine part, such as an impeller of a rotodynamic pump. The other component is stationarily housed in the machine housing. The stationary component includes damping features, which prevent or reduce the propagation of vibrations between the rotary machine component and the stationary structure of the machine.

[0020] In embodiments disclosed herein, the stationary component of the bearing includes two co-axial substantially cylindrical members, namely an internal one and an external one. The internal and external members form a gap therebetween. In the gap a resilient damping feature is arranged, which is adapted to allow dampened displacements of the external cylindrical member with respect to the internal cylindrical member. Displacements can be in a radial direction and/or in a tangential direction. Displacements can be provoked by vibrations of a rotary machine component, mounted for integral rotation with the external bearing component. The vibrations propagate through bearing pads from the outer component to the inner component and are dampened by the resilient damping feature arranged in the gap formed in the inner component, between the external cylindrical member and the internal cylindrical member thereof. This results in efficient damping of vibrations and reduced propagation of the vibrations generated by the rotary machine component towards the stationary structure of the machine.

[0021] The novel bearing structure will now be described in combination with a rotodynamic pump, and specifically with a multi-phase rotodynamic pump. Those skilled in the art will nevertheless appreciate that the bearing structure of the present disclosure can be used with advantage also in other applications, for instance whenever a relatively stiff bearing is used to support a rotary machine part subject to vibrations and damping of the vibrations is desired.

[0022] Referring now to FIG. 1, a rotodynamic pump 1 comprises a casing 3 and a stationary shaft 5 arranged therein. The stationary shaft can be formed by a beam extending longitudinally through the pump casing. In other embodiments, the stationary shaft 5 can be comprised of stacked shaft sections connected to one another by an axial tie rod. The pump can comprise a plurality of stages 7. Each pump stage 7 comprises a respective impeller 9, which is supported for rotation on the shaft 5 and coacts with a statoric part 11, i.e. with a non-rotating, stationary component of the pump 1. If the stationary shaft 5 is formed by stacked sections, each impeller 9 can be supported by a separate section of the stationary shaft 5.

[0023] Referring now to FIG. 2, with continuing reference to FIG. 1, each impeller 9 comprises a disc-shaped body 12 and a plurality of blades 13 distributed annularly around a rotation axis A-A. A process fluid path 15 extends across the bladed portion of each impeller 9. Mechanical power generated by embedded electric motors, to be described, rotate the impellers 9, which transfer the power to the process fluid along the process fluid path 15 to boost the pressure of the fluid.

[0024] In the exemplary embodiment of FIGS. 1 and 2, each impeller 9 comprises a shroud 17. Each impeller 9 is driven into rotation by a respective electric motor 18 housed in the casing 3. Each electric motor 18 includes a rotor 19, arranged around the shroud 17 and rotating with the impeller 9, as well as a stator 21 developing around the rotor 19 and stationarily housed in the casing 3.

[0025] Each impeller 9 is supported on the stationary shaft 5 by means of a respective bearing 31. In the embodiment of FIGS. 1 and 2 each bearing 31 comprises a stationary inner bearing component 31B and an outer rotary bearing component 31A. The two components 31A, 31B are substantially co-axial.

[0026] In presently preferred embodiments the bearing 31 is a PCD (Poly-Crystalline Diamond) bearing comprised of radial bearing pads 51A on the rotary outer bearing component 31A and radial bearing pads 51B on the stationary inner component 31B. Each bearing 31 can further include axial bearing pads 53A on the rotary outer bearing component 31A and axial bearing pads 53B on the stationary inner bearing component 31B or on the statoric part 11 of the pump 1.

[0027] According to embodiments disclosed herein, the inner bearing component 31B is configured to provide a vibration damping effect, such that vibrations generated by the rotating impeller 9, for instance, are dampened and not propagated, or propagated only in a dampened manner, through the respective bearing 31 towards the stationary structure 11 of the pump 1.

[0028] Referring now to FIG. 3, with continuing reference to FIG. 2, the inner stationary bearing component 31B comprises an external cylindrical member 61 and an internal cylindrical member 63. The internal and external cylindrical members 61, 63 are substantially co-axial to one another and to the stationary shaft 5, on which the internal cylindrical member 63 can be mounted. The bearing pads 51B are integral with the external cylindrical member 61.

[0029] The external cylindrical member 61 and the internal cylindrical member 63 can be coupled to one another by a ferrule 65, see FIG. 2, which can be screwed on one end of the internal cylindrical member 63. The opposite end of the internal cylindrical member 63 can form a flange 67. The external cylindrical member 61 can be pressed by screwing the ferrule 65, between the flange 67 and the ferrule 65. O-ring or similar seals 71, 73 can be arranged between the internal cylindrical member 63 and the external cylindrical member 61.

[0030] A cylindrical gap 75 is formed between the external cylindrical member 61 and the internal cylindrical member 63. The cylindrical gap 75 extends in an axial direction, i.e. parallel to the rotation axis A-A. In the cylindrical gap 75 a resilient damping feature is arranged. As used herein, the term “resilient damping feature” can be understood as any mechanical device or combination of devices arranged between the external cylindrical member 61 and the internal cylindrical member 63 and coacting therewith, such that the vibration of one said internal and external cylindrical members 63, 61 is not transmitted to the other of said internal and external cylindrical members 63, 61, or a dampened vibration is transmitted thereto.

[0031] A lubricant fluid, preferably a lubricant liquid, such as oil or other preferably high-viscosity fluid can fill the gap 75.

[0032] In some embodiments, as shown in FIG. 3, the resilient damping feature includes a corrugated tubular sheet 77. The corrugated tubular sheet 77 comprises corrugations 77A extending axially, i.e. parallel to the rotation axis A-A of the bearing 31. Due to the corrugated tubular sheet 77 arranged in the gap 75, the external cylindrical member 61 and the internal cylindrical member 63 can move one with respect to the other to a limited extent in a radial direction, for instance due to oscillations induced by vibrations of the rotary impeller 9. The radial displacement of the external cylindrical member 61 with respect to the internal cylindrical member 63 is obtained through the compliance of the corrugations 77A under a radial load applied thereto. The oscillation in radial direction is dampened by the resilient damping feature, provided by the corrugated tubular sheet 77.

[0033] In addition to a radial displacement, the external cylindrical member 61 can also move tangentially with respect to the internal cylindrical member 63, i.e. the two members 61, 63 can rotate with respect to one another by a limited angle. The tangential displacement (arrow f61, FIG. 3) can be limited by tangential displacement limiting devices. For instance said devices can include at least one, and preferably a set of first radial projections 81 extending radially inwardly from an inner surface of the external cylindrical member 61 towards the outer surface of the internal cylindrical member 63. The tangential displacement limiting devices can further include at least one, and preferably a set of second radial projections 83 extending radially outwardly from the outer surface of the internal cylindrical member 63 towards the external cylindrical member 61. The first radial projections 81 and the second radial projections 83 extend between adjacent corrugations 77A, such that the tangential displacement of the internal and external cylindrical members 63, 61 is limited by co-action of the first and second radial projections 81, 83 with the corrugations 77A.

[0034] A tangential displacement provoked by vibrations or oscillations induced by the rotary impeller causes flexural deformation of the corrugations 77A of the corrugated tubular sheet 77, which therefore dampens the oscillations.

[0035] The damping effect of the resilient damping feature can be improved by high-viscosity lubrication liquid contained in the gap 75 and/or by friction between the resilient damping feature 77 and the surfaces of the external and internal cylindrical members 61, 63 in contact with the corrugations 77A of the resilient damping feature 77.

[0036] Referring now to FIGS. 4 and 5, with continuing reference to FIG. 2, in other, currently less preferred embodiments, the resilient damping feature can include a set of compressible inserts arranged in the gap between the external cylindrical member 61 and the internal cylindrical member 63. In FIGS. 4 and 5 the same or equivalent parts or elements already shown in FIGS. 2 and 3 and described above are labeled with the same reference numbers and are not described again. In the embodiment of FIGS. 4 and 5 the resilient damping feature includes a set of O-rings 78 housed in the gap 75. Annular grooves on the inner cylindrical surface 61A of the external cylindrical member 61 and annular grooves in the outer cylindrical surface 63A of the internal cylindrical member 63 can be provided, to retain the O-rings 78 in the correct position.

[0037] Referring to FIG. 6, with continuing reference to FIG. 2, in yet further, currently less preferred embodiments, the resilient damping feature can include a set of longitudinally extending resilient members 79. In FIG. 6 the same or equivalent parts or elements already shown in FIGS. 2 and 3 and described above are labeled with the same reference numbers and are not described again. The resilient members 79 are housed in the gap 75 and can be retained in position by longitudinal grooves provided in the inner cylindrical surface 61A of the external cylindrical member 61 and longitudinal grooves in the outer cylindrical surface 63A of the internal cylindrical member 63.

[0038] While the invention has been described in terms of various specific embodiments, it will be apparent to those of ordinary skill in the art that many modifications, changes, and omissions are possible without departing form the spirit and scope of the claims. In addition, unless specified otherwise herein, the order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments.