Bushing Anti-Rotation System for Electric Submersible Pumps
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Solution Overview
Problem
Conventional bushing anti-rotation systems in electric submersible pump (ESP) assemblies fail to prevent bushing rotation at high temperatures and high gas-to-liquid ratios, leading to pump misalignment and failure.
Innovation Solution
A bushing anti-rotation system that uses mechanical wedging mechanisms, such as keys, pins, and retaining rings, to lock the bushing against rotation within the diffuser, providing a secure fit and preventing rotation even under elevated temperature and high gas content conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bushing is tightly pressed into the diffuser bore with an interference fit, then the bushing should remain stationary, but at high temperatures the bushing material expands more slowly than the diffuser, causing the press-fit to loosen and the bushing to rotate
Solution Approach 1:
The patent applies preliminary anti-action by providing a mechanical key or protrusion that prevents bushing rotation before thermal expansion can occur. The key is positioned to engage with a corresponding feature in the diffuser, creating a pre-established mechanical lock that counteracts the loosening effect of thermal expansion at high temperatures.
Solution Approach 2:
The patent employs composite materials by combining the bushing material with a key or protrusion feature that has different thermal expansion characteristics. This composite structure ensures that even when the bushing material expands differently from the diffuser at high temperatures, the key provides a rigid mechanical connection that prevents rotation.
2Device complexity
If frictional forces between the bushing and diffuser are relied upon to prevent rotation, then the design is simple, but rotational loads overcome the frictional force, causing the bushing to spin
Solution Approach 1:
The patent applies segmentation by dividing the anti-rotation function into two parts: the interference fit provides basic positioning, while a separate key or protrusion feature provides the primary anti-rotation mechanism. This segmentation allows each component to be optimized for its specific function while maintaining overall system reliability under rotational loads.
Solution Approach 2:
The patent modifies the cylindrical geometry of the bushing by adding a key or protrusion feature that creates an asymmetric shape. This geometric modification transforms the simple cylindrical interface into a keyed connection that mechanically prevents rotation while maintaining the overall compact design.
3Ease of manufacture
If the bushing is made with a standard cylindrical shape, then manufacturing is simple, but the bushing can rotate under rotational loads
Solution Approach 1:
The patent applies asymmetry by adding a key or protrusion feature to the otherwise cylindrical bushing. This asymmetric feature creates a mechanical interlock with the diffuser that prevents rotation. The asymmetric geometry is simple to manufacture using standard machining or molding processes while effectively solving the rotation problem.
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 system effectively prevents bushing rotation, maintaining thrust and radial support to the pump, extending the operational life of ESP assemblies by providing a mechanical lock against rotational loads, even at high temperatures and high gas-to-liquid ratios.
Implementation Method 1
a key extending at least partially into an eccentric cavity in the inner diameter of the diffuser and at least partially into a notch in an outer diameter of the bushing
Implementation Method 2
a pin protruding inward from the inner diameter of the diffuser, a flattened portion on an outer diameter of the bushing, and the flattened portion of the bushing wedgeable against the pin
Implementation Method 3
the at least one bent end extending into the cratered portion and the stepped portion, and the at least one bent end wedgeable against the axially extending wall of the stepped portion
Implementation Method 4
a thin layer of fluid forms in between the rotating sleeve and stationary bushing, providing hydrodynamic lift
Implementation Method 5
Frictional forces between the bushing and the surrounding diffuser attempt to keep the bushing from rotating
Implementation Method 6
The outer diameter of the bushing is larger than the diffuser bore, typically by about 0.001-0.003 inches, and is inserted using a lead in chamfer
Data Source
AI summary
A bushing anti-rotation system and apparatus. A bushing anti-rotation system includes an impeller and diffuser stage including a rotatable shaft extending longitudinally through the stage, the diffuser having an inner diameter defining a bore, a bearing set including a bushing pressed into the inner diameter, and a rotatable sleeve inward of the bushing, and means for wedging the bushing against the inner diameter of the diffuser, wherein the means for wedging provides a mechanical lock against rotation of the bushing. The means for wedging the bushing against the diffuser includes one of a key wedged between an eccentric cavity in the diffuser and a notch in the bushing, a pin protruding from the diffuser against a flattened portion of the bushing, a square-shaped bushing secured into a square-shaped bore, a bent retaining ring having a bent end that wedges against a diffuser groove wall, or a combination thereof.