ESP Motor Rotor Balancing With In-Body Balance Mass Pockets
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Solution Overview
Problem
Existing rotor balancing techniques for electric submersible pump (ESP) motors face challenges due to subtle mass variations in permanent magnets and cage structures, leading to unbalanced rotors that cause increased vibration, reduced run life, and efficiency losses, which are difficult to correct with conventional balance planes and mass addition/subtraction methods.
Innovation Solution
The use of through-hole balance masses inserted into pockets within the active length of the rotor module, positioned in interpolar spaces or lamination structures, allows for precise balancing without extending the rotor length, thereby maintaining efficiency and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional balance planes and mass addition/subtraction methods are used, then rotor balancing can be attempted, but the rotor length must be extended and manufacturing complexity increases
Solution Approach 1:
The patent transitions from conventional end-plane balancing to three-dimensional balancing within the active rotor length by utilizing interpolar spaces and lamination structures. Balance masses are distributed throughout the rotor volume rather than concentrated at ends, enabling precise balancing without extending rotor length or complicating manufacturing.
Solution Approach 2:
Balance masses are nested within existing rotor structures - specifically within interpolar spaces between magnetic poles and within lamination structures. This nesting approach allows balancing components to be integrated into the rotor's internal geometry without adding external extensions or complex assembly procedures.
2Length of moving object
If through-hole balance masses are used inserted into pockets within active length, then rotor balancing precision is improved without extending rotor length, but manufacturing precision requirements increase
Solution Approach 1:
Pockets for balance masses are pre-formed during rotor manufacturing at predetermined locations within interpolar spaces and lamination structures. This preliminary action ensures precise positioning is built into the manufacturing process itself, eliminating the need for post-assembly balancing adjustments and reducing the impact of positioning tolerances.
Solution Approach 2:
The rotor structure is designed with different local qualities - interpolar spaces and lamination structures provide specific geometric features that naturally accommodate balance masses at precise locations. These localized structural variations enable accurate balance mass positioning without requiring high-precision machining across the entire rotor.
3Manufacturing precision
If balance masses are positioned in interpolar spaces or lamination structures, then rotor balancing is achieved without extending active length, but device complexity increases
Solution Approach 1:
The rotor structure serves multiple functions: the interpolar spaces and lamination structures simultaneously provide magnetic circuit pathways and serve as locations for balance mass placement. This multi-functionality eliminates the need for separate balancing components or structures, reducing overall device complexity while maintaining high balancing precision.
Solution Approach 2:
The balancing function is merged with the rotor's magnetic circuit structure. Balance masses are integrated into interpolar spaces and lamination structures that already exist for magnetic flux pathways, combining two functions (magnetic circuit and balancing) into a single unified structure rather than adding separate balancing mechanisms.
Data Source
AI summary
Improved rotor module balancing approaches are disclosed. For example, a rotor module may be configured to be concentrically disposed on a drive shaft of an ESP motor, and may include an active length, as well as a plurality of pockets which each can extend axially into the active length and be configured to retain one of a plurality of balance masses. Such exemplary rotor modules may be balanced by determining a direction and a mass amount representing unbalance of the rotor module; based on that determination, determining specific pockets for receiving the balance masses and the amount of each corresponding balance mass; and inserting the balance masses into the corresponding pockets. Such an approach may allow for quick and efficient rotor balancing, while minimizing length of the rotor module and/or maximizing the ratio of active length versus total length of the rotor module.