Center Bushing Pockets Balance Axial Thrust in Multi-Stage Pumps
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Solution Overview
Problem
Multi-stage pumps face inefficiencies due to complex assembly and serviceability issues, as well as increased power consumption from larger bearing systems required to manage uneven axial forces, which are not effectively balanced by existing center bushing designs.
Innovation Solution
A new center bushing design with pockets on the high-pressure side to increase local pressure and balance axial forces, reducing the need for additional balance holes and O-rings, thereby minimizing leakage and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If balance holes or pump out vanes are introduced to balance axial forces, then axial thrust is reduced, but leakage between stages increases which negatively affects efficiency
Solution Approach 1:
The center bushing is designed with a specific local geometry feature - a reduced diameter section - that creates a localized pressure differential. This local modification allows axial force balancing without requiring extensive leakage paths through the entire bushing length, thus maintaining efficiency while reducing thrust.
Solution Approach 2:
Instead of balancing axial forces by creating radial leakage paths (balance holes) or modifying the impeller geometry (pump out vanes), the invention uses the axial dimension by creating a tapered or reduced diameter section along the axial length of the center bushing. This dimensional approach allows pressure differential to develop in the axial direction, providing thrust balancing with minimal radial leakage.
2Reliability
If larger bearing systems are used to handle unbalanced axial forces, then reliability is improved, but power consumption increases and overall efficiency decreases
Solution Approach 1:
The center bushing design proactively counteracts the generation of axial thrust forces by creating a pressure differential that opposes the thrust before it reaches the bearing system. This preliminary anti-action reduces the net force on the bearing, allowing for a smaller, more efficient bearing system that consumes less power while maintaining reliability.
3Force
If multiple components are assembled to reduce axial forces, then axial thrust balancing is achieved, but assembly and serviceability complexity increases
Solution Approach 1:
The invention merges the axial force balancing function directly into the center bushing component by incorporating a reduced diameter section. This integration eliminates the need for separate balancing components, vanes, or holes, reducing the total part count while achieving the same thrust reduction effect. The simplified structure improves assembly and serviceability.
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 new center bushing effectively balances axial forces, reducing thrust on the bearing system, improving efficiency and reliability by minimizing leakage and power usage, while simplifying assembly and serviceability.
Implementation Method 1
The velocity that is on the backside of the high pressure stage is reduced, which will increase the pressure locally on the backside of the respective stage
Data Source
Figure 1
Figure 2
Figure 3~3B
AI summary
A multi-stage pump featuring different stages configured to pump a fluid from a pump suction and to a pump discharge; and a center bushing configured between the different stages, having a center bushing side configured with pockets to balance axial forces between the different stages of the multistage pump. The pockets are configured as curved rib pockets, extruded circle or circular pockets, or full length rib pockets.