Impeller Foil Bearings for High-Speed Pump Shaft Stability
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Solution Overview
Problem
Centrifugal fluid pumps face challenges with shaft deflection and reduced efficiency due to unsupported impeller ends and eddy current losses in magnetic couplings, limiting rotational speed and output flow rate, which affects thermal energy transfer rates.
Innovation Solution
The introduction of impeller bearings, such as foil bearings or hydrodynamic bearings, positioned around the impeller to support the shaft and impeller, stabilizing rotations and allowing higher rotational speeds without deflection, thus increasing output flow rate and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If magnetic coupling is used to drive the impeller, then non-contact drive is achieved, but eddy current losses occur reducing efficiency
Solution Approach 1:
The patent extracts the impeller from the magnetic coupling system and supports it directly on foil bearings within the pump housing. This eliminates the magnetic coupling component entirely, removing the source of eddy current losses while maintaining the drive function through direct mechanical support and fluid coupling.
Solution Approach 2:
The patent replaces the magnetic coupling mechanism with a direct mechanical support system using foil bearings. The impeller is supported on foil bearings that provide contactless or near-contactless support, eliminating the need for magnetic fields and associated eddy current losses while maintaining rotational drive capability.
2Device complexity
If impeller is unsupported at ends, then simpler structure is achieved, but shaft deflection occurs reducing efficiency
Solution Approach 1:
The patent segments the support function by placing foil bearings at specific locations along the shaft-impeller assembly. The bearings are positioned to support both the shaft and impeller at critical points, dividing the support function into discrete bearing elements that prevent deflection without requiring a complex continuous support structure.
Solution Approach 2:
The foil bearings act as intermediaries between the shaft/impeller assembly and the pump housing. These bearings provide a compliant yet supportive interface that prevents shaft deflection and maintains impeller alignment while allowing for thermal expansion and operational variations, thereby increasing output flow rate without adding structural complexity.
3Strength
If rotational speed is limited by shaft deflection, then structural integrity is maintained, but output flow rate is reduced
Solution Approach 1:
The patent changes the support parameters by introducing foil bearings with specific material properties and geometric configurations. These bearings provide adequate support at lower rotational speeds, enabling the system to operate at higher speeds without excessive shaft deflection while maintaining structural integrity and increasing output flow rate.
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 impeller bearings enhance stability and efficiency by enabling higher rotational speeds, improving thermal energy transfer rates and reducing pump size and cost.
Implementation Method 1
The impeller bearing can be a foil bearing (e.g., a hydrostatic gas foil bearing, a foil-air bearing, a fluid bearing, etc.)
Implementation Method 2
The impeller bearing can be a foil bearing (e.g., a hydrostatic gas foil bearing, a foil-air bearing, a fluid bearing, etc.)
Data Source
AI summary
Impeller bearings for pumps are disclosed. An example fluid pump includes a motor, a shaft coupled to a rotor of the motor, an impeller coupled to the shaft forward of the motor, the impeller including expeller vanes, a first radial bearing positioned around the shaft aft of the motor, wherein the first radial bearing is a first foil bearing through which fluid flows in a first direction, and a second radial bearing positioned around the impeller, wherein the second radial bearing is a second foil bearing through which fluid flows in the first direction.