Self-Aligning Radial Support Bearing for ESP Motor
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Solution Overview
Problem
Conventional electric submersible pump (ESP) assemblies have a limited bend tolerance of 10°/100 feet, which is insufficient for modern directional drilling applications, leading to potential motor failure due to side loading on stator bearings when encountering bends in downhole wells.
Innovation Solution
The development of a self-aligning radial support bearing with a rounded roller cage and outer race forming a spheroidal joint, allowing the bearing to pivot and rock as the motor shaft bends, increasing the bend tolerance to 15°/100 feet and reducing side loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional stator bearings with constant radius outer wall are used, then the bearing structure is simple and easy to manufacture, but the bend tolerance is limited to 10°/100 feet and side loading occurs when the shaft bends
Solution Approach 1:
The outer wall of the stator bearing is changed from a constant radius cylinder to a variable radius curved surface. The curvature varies along the axial direction, with the maximum curvature at the center and decreasing toward the ends. This spheroidal geometry allows the bearing to accommodate shaft bends up to 15°/100 feet by distributing the bending stresses across the curved surface, eliminating side loading while maintaining structural integrity.
Solution Approach 2:
The radius of the outer wall is changed from a constant parameter to a variable parameter that changes along the axial direction. This parameter variation allows the bearing to adapt to different bending conditions, increasing bend tolerance while managing the complexity through a systematic geometric progression rather than arbitrary shaping.
2Length of moving object
If the shaft is made long to accommodate ESP motor requirements (27-32 feet), then the motor can function properly, but the shaft becomes more susceptible to bending and misalignment
Solution Approach 1:
The variable radius outer wall creates a curved support surface that naturally guides the long shaft into proper alignment. The curvature distribution (maximum at center, decreasing at ends) provides progressive alignment correction along the shaft length, preventing misalignment issues that would otherwise occur in long shaft applications.
Solution Approach 2:
The bearing structure is designed to dynamically adapt to shaft position changes. The variable curvature allows the bearing to self-adjust and accommodate thermal expansion, vibration, and bending forces that occur during operation of long shaft motors, maintaining reliability without rigid constraints.
3Adaptability or versatility
If conventional cylindrical bearings are used, then the manufacturing process is simple, but the bearing cannot accommodate shaft thermal expansion and bending without causing misalignment
Solution Approach 1:
The variable radius outer wall geometry provides inherent accommodation for thermal expansion and bending. As the shaft expands or bends, the curved surface allows for natural adjustment without causing misalignment, while the systematic variation in radius (maximum at center, decreasing outward) provides predictable and manufacturable geometry.
Solution Approach 2:
The radius parameter is systematically varied along the axial direction to create the adaptive geometry. This parameter change approach allows for controlled manufacturing complexity while achieving the desired adaptability, as the variation follows a defined pattern rather than requiring complex free-form shaping.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The self-aligning radial support bearing enhances the ESP assembly's ability to navigate tighter bends without failure, increasing the motor's operational reliability and extending the life of the bearings by distributing loads more effectively.
Implementation Method 1
the roller cage and outer race forming a spheroidal joint as the roller cage pivots off the longitudinal axis of the stator bore as the motor shaft bends
Implementation Method 2
The motor is filled with high dielectric oil, which lubricates the bearings and transfers heat
Implementation Method 3
The motor is filled with high dielectric oil, which lubricates the bearings and transfers heat
Data Source
AI summary
An electric submersible motor radial support bearing is described. An electric submersible motor includes a motor shaft extending longitudinally through a stator bore, the motor shaft bendable out of alignment with a longitudinal axis of the stator bore, a carrier keyed the stator bore, each rotor section of the motor separated from an adjacent rotor section by a roller bearing including a rounded roller cage between a rotatable inner race and a non-rotatable outer race, the inner race inward of the roller cage and rotatably secured to the motor shaft, the outer race having a curved inner diameter (ID) forming a roller cage socket, an outer diameter (OD) of the outer race non-rotatably secured to an ID of the carrier, the roller cage and outer race forming a spheroidal joint as the roller cage pivots off the longitudinal axis of the stator bore as the motor shaft bends.