Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-11-16
2001-05-01
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C384S291000, C384S398000, C384S286000
Reexamination Certificate
active
06225720
ABSTRACT:
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° 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° 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.
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patent: 6109790 (2000-08-01), von Gynz-Rekowski et al.
Jones Judson H.
McAfee & Taft
Ramirez Nestor
Wood Group ESP, Inc.
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