Bearing Radial Stiffness via Tolerance Rings for Rotor Stability
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Solution Overview
Problem
Small diameter, long rotary machines like well bore electric motors face challenges in maintaining rotor shaft stability at high speeds due to limited bearing radial stiffness and damping, which restricts their safe operating speed and power delivery.
Innovation Solution
The use of tolerance rings and elastomer rings to enhance radial stiffness, combined with controlled oil circulation, improves bearing performance by providing better retention and damping, allowing for higher operational speeds and increased power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the rotor shaft diameter is increased to improve shaft stiffness, then rotor shaft stability improves, but the electromagnetic design is compromised and the machine diameter increases
Solution Approach 1:
The patent applies local quality by enhancing the bearing radial stiffness specifically at critical locations along the rotor shaft, rather than increasing the overall shaft diameter. The improved bearing design with optimized clearance and damping characteristics provides localized support to improve rotor shaft stability without affecting the overall machine diameter or electromagnetic design.
2Stability of the object's composition
If the number of bearings is increased to improve rotor shaft stability, then bearing radial stiffness increases, but the cost, friction, drag, and manufacturing complexity increase
Solution Approach 1:
The patent applies parameter changes by modifying the bearing design parameters, specifically optimizing the radial clearance and damping characteristics of each bearing. This allows each bearing to provide enhanced support, reducing the need for additional bearings while maintaining rotor shaft stability. The parameter optimization enables fewer bearings to achieve the same or better stability performance.
3Speed
If the bearing radial stiffness is increased to maintain rotor shaft stability at high speeds, then safe operating speed improves, but the bearing design complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing the radial clearance and damping characteristics of the bearing to achieve higher safe operating speeds. By carefully selecting and adjusting these parameters, the bearing can maintain rotor shaft stability at high speeds without requiring overly complex design features, balancing performance with design simplicity.
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
This configuration enables small diameter, long rotary machines to operate safely at higher speeds, enhancing stability and power delivery while minimizing the number of bearings needed, thus reducing cost, friction, and manufacturing complexity.
Implementation Method 1
bearings that provide greater radial stiffness are desirable to maintain the rotor shaft stability at high rotational speeds
Implementation Method 2
bearing damping become limiting factors that determine the safe operating speed of the machine
Implementation Method 3
controlled oil circulation, improves bearing performance by providing better retention and damping
Data Source
AI summary
A bearing for a rotary machine includes an inner sleeve providing a first bearing surface and an outer sleeve circumscribing the inner sleeve and providing a second bearing surface in opposing relation to the first bearing surface. The bearing includes at least one tolerance ring for retaining the inner sleeve on a rotor shaft of the rotary machine and another tolerance ring for retaining the outer sleeve on a stator of the rotary machine.