Wet-Rotor Motor Pump Particle Management
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Solution Overview
Problem
Existing glandless motor pumps with separated stator and rotor designs face challenges in preventing abrasive particles and chemical agents from entering the rotor space, especially when the medium is contaminated, leading to potential wear and reduced service life.
Innovation Solution
A coaxial annular element is introduced on the rear side of the impeller to create an inner annular space around the motor shaft, with conveying elements like blades to guide particles to the pump suction side, and permanent magnets on a support disc to redirect magnetizable particles, ensuring they are conveyed out of the rotor space without sticking to the magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotor is flushed with the pumped medium to lubricate bearings, then the bearings are lubricated and cooled, but abrasive particles in the medium can enter the rotor space and cause wear
Solution Approach 1:
The pump chamber is divided into two separate spaces: a outer pump chamber and an inner rotor space separated by a can. This segmentation allows the pumped medium to lubricate the can exterior while preventing particle-laden medium from directly contacting the rotor bearings, thus resolving the contradiction between needing lubrication and avoiding particle contamination.
Solution Approach 2:
The can acts as an intermediary barrier between the pumped medium and the rotor space. It allows the medium to pass by for lubrication purposes while blocking direct access to the rotor bearings, thereby protecting them from abrasive particles while still enabling cooling and lubrication functions.
2Object-affected harmful factors
If blades are arranged on the impeller rear to prevent particle accumulation, then particle accumulation is reduced, but particles still penetrate the rotor space depending on pump performance
Solution Approach 1:
The invention adds a radial dimension to particle control by creating an annular space between the can and the impeller rear. This new spatial dimension allows particles to be directed radially outward by the impeller blades toward discharge openings in the can, preventing them from penetrating axially into the rotor space, thus enhancing particle prevention effectiveness.
Solution Approach 2:
The can is designed with discharge openings positioned to intercept particles before they can reach the rotor space. The impeller blades are configured to redirect particles toward these pre-positioned openings, performing preliminary particle removal action before particles could cause harm to the rotor bearings.
3Reliability
If a can separates the stator from the rotor, then the stator is protected from the medium, but particles can still accumulate in the annular space behind the impeller and potentially enter the rotor space
Solution Approach 1:
The invention extracts the particle accumulation problem from the sealed annular space by providing dedicated discharge openings in the can. These openings allow particles that accumulate in the annular space to be extracted and discharged to the pump suction side, preventing their migration into the rotor space while maintaining the protective separation function of the can.
Solution Approach 2:
Particles that accumulate in the annular space are discarded through discharge openings in the can to the pump suction side. This discarding mechanism prevents particles from being recovered or retained in the rotor space, thereby protecting the rotor bearings from wear while maintaining the can's protective separation function.
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 minimizes the entry of particles and chemical agents into the rotor space, enhancing the pump's service life and maintaining efficiency by ensuring particles are pumped away and not accumulating, thus preventing wear and maintaining performance.
Implementation Method 1
permanent magnets being attached to the rear of the support disc for capturing particles contained in the pumped liquid
Implementation Method 2
the side of the magnet that faces the conveying flow on the rear side of the carrier disc is covered by a layer of material. The layer of material covering the magnets ensures that the magnetisable particles do not stick to the magnets of the impeller, but are conveyed into the pump chamber by the centrifugal forces acting on the back of the impeller
Implementation Method 3
the rear side of the impeller carries conveying elements, in particular in the form of blades, which circulate the liquid in the annular space
Implementation Method 4
The hollow motor shaft has at least one radial opening, bore or groove at the level of the ring element, through which liquid flows from the inner ring space surrounded by the ring element into the shaft cavity, so that particles are also discharged to the suction side
Data Source
Figure 1
AI summary
The invention relates to a wet-rotor motor pump comprising a can which separates the motor stator from the rotor mounted in the can on a motor shaft, said motor shaft projecting into the pump chamber and carrying, in said pump chamber, the impeller. A coaxial annular space, which is open towards the pump chamber, is provided on the rear of the impeller, the pumped liquid flowing from the annular space into the rotor space through at least one flow passage in the separating wall, and flowing back to the pump chamber once it has permeated the rotor space. The rear of the impeller has a throttled throughflow opening in the region of the annular space, said throughflow opening connecting the annular space to the interior of the impeller, especially to the pump intake side.