A self-lubricating bearing for use in submersible oil-filled motors is disclosed. The bearing comprises a bearing housing and is fixed against rotation. A bearing sleeve is disposed in the bearing housing. The bearing sleeve is fixed in the bearing housing, and has a slot disposed therethrough. The bearing housing has an inlet and an outlet defined therethrough that intersect the slot in the bearing sleeve. The bearing is disposed about a rotatable shaft in the motor. Rotation of the shaft will cause oil to be drawn in through the inlet so that the shaft and the bearing surface of the bearing sleeve are lubricated. Rotation will also cause oil drawn in through the inlet to be expelled through the outlet back into the motor so that there is a constant circulation of oil through the bearing to provide lubrication.

BACKGROUND OF THE INVENTION
 This invention relates to a self-lubricating bearing for oil-filled
 machines, and more particularly to a rotor bearing for use in submersible
 oil-filled motors.
 Submersible pumps are typically centrifugal pumps that are driven by
 submersible motors which rotate a shaft extending from the motor to the
 pump. Motors utilized to drive such pumps for oil and water production may
 vary in length from approximately six to over thirty feet in length. Such
 motors typically have a stator secured within a tubular outer housing and
 a rotor secured to the shaft which rotates within the stator.
 Because of the length of the motor, rotors are generally made up of a
 number of rotor sections that may comprise a large number of flat disks,
 or laminations, that are secured to one another and to the shaft in any
 way known in the art. For example, the rotors may be keyed to the shaft
 and have retaining rings at the upper and lower ends thereof to prevent
 axial movement. The rotor sections are spaced apart longitudinally from
 one another in the motor. Rotor bearings are utilized in the motor to
 stabilize the shaft, and are typically located between rotor sections and
 at the upper and lower ends of the rotor. The rotor bearing generally
 includes a bearing housing having a sleeve disposed therein. The bearing
 housing is adapted to engage the inner wall of the stator to prevent
 rotation of the bearing housing in the motor, and the sleeve is in most
 instances keyed to the shaft so that the sleeve will rotate with the shaft
 inside the bearing housing. The bearings must be lubricated so as to
 prevent overheating and/or premature failure. Therefore, shafts in such
 motors are typically hollow tubular shafts with axial bores therethrough.
 The axial bore extends upwardly from the lower end of the shaft and is
 plugged at the top. A radial port will extend through the shaft and the
 bearing sleeve at each bearing location and will intersect the axial bore
 so that oil can be communicated from the axial bore in the shaft to be
 inner surface of the bearing housing to lubricate the sleeve rotating
 therein. While such a configuration works adequately, reliable lubrication
 of bearings is a concern. There is some question as to whether the oil is
 adequately distributed, so that the bearings at the top of the motor
 receive the same amount of oil as those near the bottom, and whether or
 not such bearings are adequately lubricated. Furthermore, if the axial
 bore or one of the radial bores becomes plugged one or more bearings may
 receive restricted oil flow, or no flow at all, which will cause
 overheating and failure. Bearings that become worn must be replaced, which
 is time-consuming and costly. There is therefore a need for an apparatus
 which can create a reliable, constant oil flow rate through a rotor
 bearing which will allow the bearing to run cooler and which will allow
 for a longer bearing life.
 SUMMARY OF THE INVENTION
 The present invention meets the foregoing needs by providing a
 self-lubricating rotor bearing. The rotor bearing is configured to allow a
 high oil flow rate through the bearing to lubricate the bearing surface so
 that the bearing runs cooler and has a longer life than prior art rotor
 bearings. The rotor bearing of the present invention may be used in
 machines that are at least partially filled with oil and are specifically
 adapted for use in oil-filled, submersible motors used in the production
 of water and/or oil from a wellbore.
 The bearing is adapted to be disposed in an oil-filled motor housing and to
 be fixed to a stator that has been secured in the motor. The rotor bearing
 will engage the stator so that as the shaft extending through the motor
 rotates, the rotor bearing is fixed against rotation. The bearing has an
 inner surface and an outer surface, and has first and second ports
 extending through the bearing from the outer surface to the inner surface
 thereof A groove is defined in the inner surface of the bearing, and
 preferably extends around about 180.degree. of the inner diameter of the
 bearing. The first and second ports comprise an inlet and an outlet, which
 provide for the intake of the oil from the motor housing through the
 bearing and the discharge of oil from the interior of the bearing into the
 motor housing. Oil is therefore communicated through the bearing to the
 inner or bearing surface of the bearing to lubricate the shaft, or a shaft
 sleeve keyed to the shaft, as the shaft rotates in the bearing.
 The bearing of the present invention preferably comprises an outer housing,
 which may be referred to as a bearing housing, and an inner or bearing
 sleeve. The outer surface of the bearing is defined on the bearing
 housing, and the inner surface of the bearing is defined on the bearing
 sleeve. The bearing sleeve is a generally cylindrical sleeve having a slot
 defined therethrough extending around a portion of the periphery thereof
 The slot preferably extends through at least about 180.degree. and defines
 the groove in the inner surface of the bearing. The first and second ports
 extending through the bearing from the outer surface thereof to the inner
 surface thereof intersect the slot. The first and second ports therefore
 define a flow path through the bearing. Rotation of the shaft will cause
 oil from the motor housing to be drawn into the bearing through one of the
 first or second ports to provide lubrication to the bearing surface so
 that the shaft extending therethrough can rotate freely. A continuous flow
 of oil is provided since the oil drawn in through one port will be
 expelled through the other of the ports thus allowing the bearing to run
 cooler and last longer than prior art bearings.
 The bearing housing is preferably generally cylindrically shaped with a
 pair of notches defined in the outer surface thereof The first and second
 ports intersect the notches and have first and second longitudinal axes
 respectively. The first and second longitudinal axes of the first and
 second ports are preferably parallel to one another. The notches defined
 in the outer surface of the bearing create oil reservoirs in the motor
 housing adjacent the first and second ports so that a constant supply of
 oil to lubricate the bearing is readily available and so that a reservoir
 is readily available for oil discharged from the bearing.
 The bearing of the present invention thus meets a number of needs and
 provides a number of advantages over the prior art bearings. These and
 other objects and advantages of the present invention will become apparent
 after studying the detailed description of the invention in view of the
 accompanying drawings and appended claims.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
 Referring now to the drawings and more particularly to FIGS. 1A-1C, a motor
 10 having a plurality of bearings 15 disposed therein is shown. A tool
 string 20 including motor 10 is schematically depicted in FIG. 7. As shown
 therein, tool string 20 is disposed in a wellbore 25 which is drilled for
 the production of a production fluid such as water or oil. Tool string 20
 includes motor 10, a seal section 30, an intake section 35, and a
 submersible pump 36. Tubing 40 is communicated with pump 36 and extends to
 a wellhead 41.
 Referring now back to FIGS. 1A-1C, motor 10 includes a motor housing 50
 which has an upper end or head 55 and a lower end or base 57. Motor
 housing 50 is at least partially filled with oil, or other lubricating
 fluid known in the art. Motor 10 has a shaft 60 extending therethrough.
 Shaft 60 may have a coupling 64 at the upper end 62 thereof, to connect
 shaft 60 to a shaft 65 which extends upwardly from motor 10 to pump 36.
 The motor will thus drive pump 36 so that production fluid in the wellbore
 can be pumped to the wellhead. Shaft 60 disposed in motor housing 50 may
 have a longitudinal or axial passage 63 extending therethrough. Shaft 60
 has a lower end 66 which may have an oil filter 68 connected thereto and
 has an outer surface 69. The oil in motor housing 50 may be communicated
 with passage 63 through filter 68.
 Motor 10 further includes a stator 70 rigidly mounted to housing 50. Stator
 70 will normally be made up of a number of flat laminations 73 as depicted
 in FIG. 8. Stator 70 defines an inner diameter 72 having a plurality of
 slots 74 uniformly spaced therein in a circular pattern. Motor 10 has a
 rotor 76 fixed to shaft 60 and is comprised of a plurality of spaced rotor
 sections 78. An electrical current is directed into stator 70 through a
 lead cable 80 which is connected to a power source (not shown). The
 electrical current which passes through stator 70 will cause rotor 76 to
 rotate thus rotating shaft 60.
 As is apparent from FIGS. 1A-1C, motor 10 may include a plurality of
 bearings 15 disposed about shaft 60 to stabilize the shaft over the length
 of the motor. Motor 10 may also include a plurality of shaft sleeves 82
 disposed about and fixed to shaft 60. Shaft sleeves 82 may be keyed, or
 otherwise affixed to shaft 60 in any manner known in the art so that shaft
 sleeve 82 will rotate with shaft 60. A shaft sleeve 82 may be disposed
 about shaft 60 at each location where a bearing 15 is located, and will be
 positioned between shaft 60 and bearings 15 so that bearings 15 are
 disposed about shaft sleeves 82. Shaft sleeves 82 have an outer surface
 83.
 Bearings 15 are positioned between rotor sections 78 and at the upper and
 lower ends 84 and 86 thereof. Because the length of motor 10 can vary, the
 number of rotor sections 78 required to make up rotor 76, along with the
 number of bearings 15, will vary with the length of the motor. In other
 words, the greater the length, the greater the number of bearings and
 rotor sections.
 Referring now to FIGS. 2-6, bearing 15 comprises an outer surface 90 and an
 inner surface 92, which defines an inner diameter 94. Inner surface 92
 comprises the bearing surface of the bearing 15. A groove 96 having a
 first end 98 and a second end 100 is defined in inner surface 92 of
 bearing 15. First and second ports 102 and 104, respectively, extend
 through bearing 15 from the outer surface 90 to the inner surface 92
 thereof, so that oil in motor housing 50 may be communicated therethrough
 between outer surface 90 and bearing surface 92 through first and second
 ports 102 and 104. Thus, first and second ports 102 and 104 comprise an
 inlet and an outlet for the flow of fluid from the motor housing through
 bearing 15. First port 102 has a longitudinal axis 103, and second port
 104 has a longitudinal axis 105. Axes 103 and 105 are preferably parallel.
 Bearing 15 comprises an outer or bearing housing 106 and an inner or
 bearing sleeve 108. Outer surface 90 is defined on bearing housing 106 and
 inner or bearing surface 92 is defined on bearing sleeve 108. Bearing
 sleeve 108 is fixed in housing 106 to prevent rotation of the bearing
 sleeve therein. A slot 110, which comprises groove 96, is defined through
 sleeve 108 and has first and second ends 112 and 114. Slot 110 preferably
 extends between about 170.degree. and 190.degree., the periphery of sleeve
 110 and more preferably extends through about 180.degree.. First and
 second ports 102 and 104 intersect slot 110, so that ports 102 and 104 and
 slot 110 comprise a continuous flow path for oil or other lubricating
 fluid in motor housing 50. Bearing 15 is a generally cylindrically shaped
 bearing and thus bearing housing 106 is generally cylindrically shaped and
 has a pair of notches 112 and 114 defined thereon. Port 102 has a first
 end 120 intersecting flat 116 of notch 112, and has a second end 122. Port
 104 has a first end 124 intersecting flat 118 of notch 114, and has a
 second end 126. Ports 102 and 104 are preferably spaced so that ends 122
 and 124 intersect inner diameter 94 about 180.degree. apart. Outer surface
 90 has a plurality of outwardly extending ridges 128 defined thereon,
 which will be received in slots 74 defined in stator 70. Because ridges
 128 are received in slots 74, bearing 15 will not rotate in motor housing
 50 as shaft 60 rotates.
 Ports 102 and 104 will act as an inlet and an outlet through bearing 15.
 When shaft 60 rotates counterclockwise, port 104 will act as an inlet and
 port 102 will act as an outlet. Notches 112 and 114 formed in the outer
 surface of the bearing provide natural reservoirs in motor housing 50. As
 fluid is drawn into port 104, rotation of the shaft will cause the fluid
 to flow into slot 110 and to spread out over bearing surface 94 to provide
 lubrication between shaft sleeve 82 and bearing 15. Oil will be expelled
 through port 102 so that there is a continuous flow of oil or other fluid
 into and through the bearing to provide constant lubrication. The
 continuous flow of oil through bearing 15 results in longer bearing life
 and provides an economic advantage since the motor housing will have to be
 disassembled less frequently than motors using prior art bearings.
 Rotation in a clockwise direction simply changes 102 from an outlet to an
 inlet and 104 from an inlet to an outlet, and the bearing operates in the
 manner described herein.
 The invention is described as including a shaft sleeve 82, such that the
 outer surface 83 of sleeve 82 runs on the lubricated inner surface of
 bearing 15. If desired, the shaft sleeve can be eliminated so that the
 shaft itself runs on the bearing surface.
 The bearing of the present invention may be made of any number of materials
 used for such components, but is preferably comprised of a stainless steel
 housing with a bronze inner sleeve. The present invention thus provides
 for a higher oil flow rate through the bearing than is capable with prior
 art bearings. The bearing virtually insures a continuous flow of oil and
 almost eliminates the possibility that a bearing will be starved of oil.
 Thus, a more efficient, reliable and longer-lasting bearing is provided.
 The bearing of the present invention is well adapted to be used in any
 oil-filled material but a preferred application is for use in submersible
 water well pump and submersible oil pump motors.
 Although the invention has been described with reference to a specific
 embodiment, the foregoing description is not intended to be construed in a
 limiting sense. Various modifications as well as alternative applications
 will be suggested to persons skilled in the art by the foregoing
 specification and illustrations. It is therefore contemplated that the
 appended claims will cover any such modifications, applications or
 embodiments that fall within the true scope of the invention.