Centrifugal Pump Impeller Magnet Covering for Particle Redirection
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Solution Overview
Problem
Existing centrifugal pump impellers with rear support discs and attached permanent magnets face issues where magnetizable particles stick to the magnets, reducing efficiency and potentially entering the bearings or motor rotor space, causing wear.
Innovation Solution
A disc or cap with a non-stick coating is attached to the rear of the impeller, covering the magnets, ensuring that magnetizable particles are redirected by centrifugal forces into the pump chamber rather than adhering to the magnets, using a low magnetic force and a non-magnetic material like plastic or a DLC coating to prevent sticking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If permanent magnets are attached to the back of the impeller to capture magnetizable particles, then particle capture capability is improved, but flow resistance increases and efficiency decreases due to particle adhesion to magnets
Solution Approach 1:
A non-magnetic covering layer (plastic, rubber, or coated surface) is introduced as an intermediary between the magnets and the magnetizable particles. This layer allows the magnets to exert magnetic force on particles while preventing direct contact and adhesion, thus maintaining particle capture capability without the efficiency penalty of particle sticking to the magnets themselves
Solution Approach 2:
The magnetic flux density is optimized to a specific range (0.02-0.2 Tesla) to ensure sufficient particle capture force while avoiding excessive magnetic attraction that would cause particle adhesion. The covering layer thickness is also optimized (0.4-2 mm) to provide adequate protection while maintaining magnetic effectiveness
2Reliability
If permanent magnets are attached to the back of the impeller to capture particles, then particle removal from flow path is improved, but particles may still enter bearings and motor rotor chamber causing wear
Solution Approach 1:
The non-magnetic covering layer serves as a protective intermediary that redirects captured particles toward the pump outlet rather than allowing them to enter the bearing and motor rotor chamber. The layer's smooth, non-stick surface ensures particles are conveyed away safely after being deflected by the magnetic field
Solution Approach 2:
The magnetic force that could potentially cause particle adhesion and efficiency loss is converted into a beneficial redirecting force. By optimizing the magnetic flux density and using a non-magnetic covering, the magnetic field successfully deflects particles toward the outlet while preventing harmful adhesion, turning a potential harm into a useful particle removal mechanism
3Productivity
If a covering layer is added to protect magnets from particle adhesion, then impeller efficiency is maintained, but device complexity increases
Solution Approach 1:
The covering layer is integrated directly into the impeller structure, merging the protective function with the existing impeller design. The layer can be formed as part of the impeller body or attached as a simple component, combining multiple functions (structural support, particle redirection, magnetic field protection) into a unified design that minimizes additional complexity
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
This solution effectively prevents magnetizable particles from adhering to the impeller, maintaining efficiency by ensuring they are conveyed to the pump outlet, reducing wear and flow resistance, with optimal results achieved through specific magnetic flux density and distance configurations.
Implementation Method 1
permanent magnets are attached to the rear of the support disc for capturing particles contained in the pumped fluid
Implementation Method 2
The magnets therefore have a diverting effect on the magnetizable particles, ensuring that they do not stick to the magnets
Implementation Method 3
The material layer covering the outer surface of the disc or cap ensures that the magnetizable particles do not adhere to the magnets of the impeller, but are instead conveyed into the pump chamber by the centrifugal forces acting on the back of the impeller
Data Source
Figure 1
Figure 2
AI summary
The impeller has a rear-side support plate (7) on which several runner blades (8) are arranged by which rear side of the permanent magnets (12) are secured. Permanent magnets are arranged within the extrusion-coated plastic side of the rear-side support plate for trapping the feed liquid particles present in the impeller main portion. A material layer is arranged on the side of the magnets which are faced on the rear-side support plate for covering the magnet and rear-side support plate, such that the coverage of injection-molded portion is formed.