Wet-Running Pump Bearing Retainer With Circular Bypass Flow
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Solution Overview
Problem
Wet-running centrifugal pumps face issues with limescale precipitation and magnetite accumulation due to fluid flow, leading to increased frictional losses and wear, as well as the risk of rotor shaft blockage from temperature differences and thermal expansion when not in operation.
Innovation Solution
A pump bearing retainer design with first and second axial fluid channels that facilitate a circular flow between the rotor chamber and impeller chamber, driven by a Tesla pump effect, reducing magnetite accumulation and minimizing fluid flow along the lubrication film when the pump is not running, thereby preventing limescale precipitation and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluid flows axially along the lubrication film between the rotor shaft and the radial bearing when the pump is not running, then temperature differences and thermal expansion cause fluid breathing, but this leads to precipitation and sedimentation of limescale between the rotor shaft and the radial bearing
Solution Approach 1:
The invention extracts the fluid flow path from the lubrication film area by providing dedicated axial fluid channels in the bearing retainer. The fluid is diverted to flow through these channels instead of along the lubrication film, preventing limescale precipitation while maintaining necessary fluid circulation for thermal management.
Solution Approach 2:
The axial fluid channels act as an intermediary structure that mediates between the rotor chamber and impeller chamber. This intermediary flow path allows fluid to bypass the lubrication film area, preventing harmful limescale deposition while still enabling thermal equilibrium between components.
2Productivity
If significant fluid flow occurs from the impeller chamber through the bearing retainer holes into the rotor chamber during pump operation, then pressure differences drive the flow, but this introduces magnetite into the rotor chamber which accumulates at the rotor
Solution Approach 1:
The invention extracts the fluid flow path from the traditional bearing retainer holes configuration and reconfigures it into axial fluid channels with controlled flow directions. This allows the fluid to circulate between chambers without introducing magnetite-laden fluid into the rotor chamber, eliminating magnetite accumulation while maintaining pump productivity.
Solution Approach 2:
The invention inverts the traditional flow direction concept by creating opposite axial flow directions in different channels. One channel directs fluid from rotor to impeller chamber, while another directs fluid from impeller to rotor chamber, creating a balanced circulation that prevents magnetite accumulation.
3Temperature
If fluid flows along the lubrication film between the rotor shaft and the radial bearing, then thermal expansion is accommodated, but frictional losses increase due to magnetite accumulation
Solution Approach 1:
The invention extracts the fluid flow function from the lubrication film path and relocates it to dedicated axial fluid channels. This separation allows the lubrication film to maintain its primary function of accommodating thermal expansion while preventing the introduction of magnetite that would increase frictional losses.
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 design significantly reduces the risk of pump blockage and frictional losses by minimizing magnetite accumulation and limescale precipitation, ensuring efficient operation and extended pump lifespan by providing an alternative flow path of low resistance.
Implementation Method 1
there is a significant fluid flow caused by significant pressure differences from the impeller chamber through the bearing retainer holes into the rotor chamber
Implementation Method 2
allows for a circular flow out of a rotor chamber of the pump into an impeller chamber of the pump through the first axial fluid channel(s) and back from the impeller chamber into the rotor chamber through the second axial fluid channel(s)
Implementation Method 3
a radial bearing with an inner sliding surface configured to allow a lubrication film between the inner sliding surface and a rotor shaft of a pump
Implementation Method 4
The magnetite is magnetically attracted by the permanent magnets of the rotor and accumulates at the rotor over time
Implementation Method 5
when the pump is not running, due to temperature differences and thermal expansion of the fluid, fluid flows axially along the lubrication film between the rotor shaft and the radial bearing
Data Source
AI summary
A wet-running pump bearing retainer (29) includes a radial bearing configured for a lubrication film between an inner sliding surface (41) and a rotor shaft (13) of a pump (1). The radial bearing is fitted into a radially inner section (49) that defines an axial fluid channel (45), located at a first radial distance (D1) to a rotor axis (R) and providing a fluid flow path (F1) in a first axial flow direction. The first radial distance is larger than a radius (D0) of the inner sliding surface. A radially outer section (51) extends from the inner section and defines a second axial fluid channel (47) for a flow path (F2) in a second axial flow direction, opposite to the first flow direction. The second axial fluid channel is located at a second radial distance (D2) to the rotor axis, which is larger than the first radial distance.