Compliant Bushing Design for Submersible Pump Thrust Bearings
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Solution Overview
Problem
In electrical submersible pumps, the press-fit installation of tungsten carbide bushings into diffuser receptacles can lead to misalignment, wear, and damage due to load concentrations and vibrations, especially in abrasive fluid environments, causing carbide chattering and heat generation at bearing surfaces.
Innovation Solution
A bushing with an axially movable design, supported by a stationarily mounted member of lesser hardness, utilizing a spring to bias the bushing axially and prevent rotation, combined with axial and radial coolant grooves for cooling, reduces axial and radial movement to mitigate damage and chattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard tungsten carbide bushing is press fit into the diffuser receptacle, then wear resistance is improved, but misalignment and damage occur due to load concentrations and vibrations
Solution Approach 1:
The bushing is designed to be axially movable relative to the diffuser receptacle, transitioning from a fixed rigid position to a dynamic compliant position. This allows the bushing to absorb axial movements and vibrations, preventing misalignment and damage while maintaining wear resistance through the hard tungsten carbide material.
Solution Approach 2:
A spring element is introduced between the bushing and the diffuser receptacle to provide beforehand cushioning. The spring absorbs shock and vibration before they can cause misalignment or damage to the rigid tungsten carbide bushing, protecting the alignment stability while preserving wear resistance.
2Duration of action of stationary object
If the bushing is made of carbide material for abrasion resistance, then durability in abrasive environments is improved, but carbide chattering occurs due to vibration
Solution Approach 1:
The axially movable bushing design introduces dynamic compliance that absorbs vibrations, preventing the carbide material from chattering. The movement capability allows the bushing to respond to vibrational forces rather than rigidly resisting them, eliminating chattering while preserving durability.
Solution Approach 2:
The vibration forces that previously caused harmful carbide chattering are converted into beneficial axial movement of the bushing. The compliant design allows vibrations to be absorbed and dissipated through controlled movement, transforming a harmful effect into a protective mechanism that maintains durability without chattering.
3Stability of the object's composition
If the bushing is rigidly fixed in the receptacle, then positioning stability is improved, but heat generation damages the bearing surfaces
Solution Approach 1:
The axially movable bushing design introduces dynamic compliance that reduces friction and heat generation at the bearing surfaces. By allowing controlled axial movement, the design prevents rigid contact and friction-induced heating while maintaining sufficient positioning stability for proper pump operation.
Solution Approach 2:
The spring element provides beforehand cushioning that reduces impact loads and friction between the bushing and bearing surfaces. This cushioning effect prevents excessive heat generation by distributing loads more evenly, while the bushing maintains adequate positioning stability through the spring's supportive action.
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 solution effectively reduces damage and misalignment by allowing axial compliance of the bushing, minimizing wear and chattering, and enhances cooling through coolant grooves, thereby improving the operational reliability and longevity of the pump components.
Implementation Method 1
A spring is located between and in engagement with the thrust transferring surface of the bushing and the thrust receiving shoulder of the receptacle. The spring biases the bushing axially in a direction opposite to the thrust.
Implementation Method 2
At least one axially extending pin extends between the supporting member and the bushing for preventing rotation of the bushing relative to the supporting member. The pin preferably extends from the thrust receiving shoulder of the supporting member and fits into mating profile in the bushing.
Data Source
AI summary
An electrical submersible pump assembly includes a centrifugal pump having impellers and diffusers. A thrust runner is coupled to a motor shaft for rotation along with the impellers. The runner receives thrust from at least one of the impellers and transfers the thrust to a bushing non rotatably mounted in one of the diffusers. The bushing has a thrust transferring end adjacent a thrust receiving shoulder in the diffuser. The bushing is axially movable in the receptacle. An annular spring located between the thrust receiving shoulder in the receptacle and the thrust transferring end of the bushing urges the bushing away from the thrust receiving shoulder.