Thrust bearing with tilting pad
A thrust bearing for an electric submersible pump includes a housing including an axial surface and an inner circumferential surface. Holes and bores are formed in the axial surface. The thrust bearing further includes sockets respectively disposed in the holes and pads each including a fluid interface surface. Two open counterbores are formed in each of the pads. The inner circumferential surface radially constrains the pads. The thrust bearing further includes balls each engaging one of the sockets and one of the pads and retaining bolts each including a head and a shaft extending from the head. Each of the shafts is disposed in one of the bores. The thrust bearing further includes biasing members each disposed between a bearing surface of one of the heads and bottom surfaces of two of the open counterbores. The pads are able to pivot on the ball.
1 . A thrust bearing for an electric submersible pump, comprising:
a housing comprising an axial surface and an inner circumferential surface, wherein holes and bores are formed in the axial surface;
sockets respectively disposed in the holes;
pads each comprising a fluid interface surface, wherein two open counterbores are formed in each of the pads, and wherein the inner circumferential surface radially constrains the pads;
balls each engaging one of the sockets and one of the pads;
retaining bolts each comprising a head and a shaft extending from the head, wherein each of the shafts is disposed in one of the bores; and
biasing members each disposed between a bearing surface of one of the heads and bottom surfaces of two of the open counterbores.
2 . The thrust bearing of claim 1 , wherein the sockets each comprise an inner frustoconical surface, the pads each comprise an inner conical surface, and each of the balls engages one of the inner frustoconical surfaces and one of the inner conical surfaces.
3 . The thrust bearing of claim 1 , wherein each of the pads is configured to tilt about the ball in a radial direction.
4 . The thrust bearing of claim 1 , wherein each of the pads is configured to tilt about the ball in a tangential direction.
5 . The thrust bearing of claim 1 , wherein there is clearance between the heads and the pads.
6 . The thrust bearing of claim 1 , further comprising lock washers disposed between the housing and the retaining bolts.
7 . The thrust bearing of claim 1 , further comprising shims disposed between the housing and the sockets, wherein the shims are configured to set positions of the faces of the pads.
8 . The thrust bearing of claim 1 , wherein the fluid interface surface comprises a first edge feature disposed at a first end of the pad, a second edge feature disposed at a second end of the pad, and a flat surface extending from the first edge feature to the second edge feature.
9 . The thrust bearing of claim 8 , wherein the first edge feature and the second edge feature each comprise a concavely curved surface.
10 . The thrust bearing of claim 8 , wherein the first edge feature and the second edge feature each comprise a convexly curved surface.
11 . The thrust bearing of claim 8 , wherein the first edge feature and the second edge feature each comprise a chamfer.
12 . The thrust bearing of claim 8 , wherein
each of the pads comprises a first chamfer proximate the first edge feature and a second chamfer proximate the second edge feature, and
the open counterbores are formed in the first chamfers and the second chamfers.
13 . The thrust bearing of claim 1 , wherein there are spaces between the pads.
14 . The thrust bearing of claim 1 , wherein the biasing members bias the pads in an axial direction.
15 . The thrust bearing of claim 1 , wherein the fluid interface surfaces are configured such that a fluid film is formed between the fluid interface surfaces and a thrust runner when there is relative motion between the fluid interface surfaces and the thrust runner.
16 . The thrust bearing of claim 1 , wherein each of the pads is configured to tilt with the ball about the socket in a radial direction.
17 . The thrust bearing of claim 1 , wherein each of the pads is configured to tilt with the ball about the socket in a tangential direction.
18 . A method of assembling the thrust bearing of claim 1 , comprising:
placing the sockets in the holes;
placing the balls on the sockets;
placing the pads on the balls;
constraining the pads from moving using fixtures mounted between the pads, wherein the fixtures are bolted to the housing using mounting bolts that extend into the bores;
lapping the fluid interface surfaces;
removing the fixtures from the pads;
placing the biasing members on the bottom surfaces of the open counterbores such that each of the biasing members contacts two of the bottom surfaces; and
bolting the retaining bolts to the housing, wherein the shafts extend through the biasing members.
19 . A method of assembling an electric submersible pump, comprising:
interfacing the thrust bearing of claim 1 with a thrust runner affixed to a shaft connected to an electric motor of an electric motor assembly;
connecting the electric motor assembly to a seal unit; and
connecting the seal unit to a centrifugal pump.
20 . A method of lifting fluid in a wellbore, comprising:
running the electric submersible pump assembled by the method of claim 19 into a wellbore; and
providing electric power to the electric motor.
21 . A thrust bearing for an electric submersible pump, comprising:
a housing comprising an axial surface, an inner circumferential surface, and first conical surfaces, wherein bores are formed in the axial surface;
pads each comprising fluid interface surfaces and second conical surfaces, wherein two open counterbores are formed in each of the pads, and wherein the inner circumferential surface radially constrains the pads;
balls each engaging one of the first conical surfaces and one of the second conical surfaces; and
retaining bolts extending through the bores and the open counterbores to retain the pads.
22 . The thrust bearing of claim 21 , further comprising biasing members, wherein the retaining bolts each comprise a head and a shaft extending from the head, wherein each of the shafts is disposed in one of the bores, and wherein the biasing members are each disposed between a bearing surface of one of the heads and bottom surfaces of two of the open counterbores.
23 . A thrust bearing for an electric submersible pump, comprising:
a housing comprising an axial surface and an inner circumferential surface, wherein holes and bores are formed in the axial surface;
sockets comprising first conical surfaces, wherein the sockets are disposed in the holes;
pads each comprising fluid interface surfaces and second conical surfaces, wherein two open counterbores are formed in each of the pads, and wherein the inner circumferential surface radially constrains the pads;
balls each engaging one of the first conical surfaces and one of the second conical surfaces; and
retaining bolts extending through the bores and the open counterbores to retain the pads.
24 . The thrust bearing of claim 23 , further comprising biasing members, wherein the retaining bolts each comprise a head and a shaft extending from the head, wherein each of the shafts is disposed in one of the bores, and wherein the biasing members are each disposed between a bearing surface of one of the heads and bottom surfaces of two of the open counterbores.