Wet Rotor Pump Hydraulic Balancing Without Axial Bearing
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Solution Overview
Problem
Wet rotor pumps face challenges with axial thrust bearings that require installation space, increase costs, cause friction losses, and are prone to wear and sticking, especially in multi-stage pumps where conventional bearings cannot accommodate large axial forces effectively.
Innovation Solution
A wet rotor pump design featuring a second annular wall that separates the impeller side space into two annular spaces, forming a radially flowable axial throttling gap with a variable width, combined with a radial sealing gap and a relief bore, allowing the impeller to adjust its axial position automatically to achieve equilibrium without a traditional axial bearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a thrust bearing is used to absorb axial force, then the axial force is compensated, but installation space increases, costs increase, system complexity increases, friction losses increase, and noise increases
Solution Approach 1:
The patent removes the thrust bearing from the system by using a relief bore that drains fluid from the impeller rear side to the suction side, creating a pressure imbalance that eliminates axial thrust without requiring a bearing to absorb it
Solution Approach 2:
The invention uses hydraulic principles by creating a pressure differential through the relief bore, where fluid flow from the high-pressure rear side to the low-pressure suction side generates a force that balances the axial thrust on the impeller
2Force
If a thrust bearing is used to absorb axial force, then the axial force is compensated, but friction losses increase
Solution Approach 1:
The thrust bearing is completely removed from the system, eliminating the source of friction losses while still achieving axial force compensation through the relief bore mechanism
Solution Approach 2:
Hydraulic pressure differential created by the relief bore replaces the mechanical friction-based thrust bearing, transferring the force balance mechanism from a contact-based mechanical system to a non-contact hydraulic system that avoids friction losses
3Force
If a relief system is used to reduce axial forces, then bearing load is decreased, but volumetric losses and frictional losses in the relief system increase
Solution Approach 1:
The relief bore is positioned and dimensioned to optimize the pressure differential and flow characteristics, minimizing the volumetric and frictional losses while still achieving effective axial force reduction
Solution Approach 2:
The relief system uses the pump's own fluid flow and pressure differential to automatically balance axial forces, with the relief bore passively utilizing the existing hydraulic conditions without requiring additional energy input or complex control mechanisms
4Force
If a thrust bearing is used to absorb axial force, then the axial force is compensated, but the system is subject to wear and sticking, and reliability decreases
Solution Approach 1:
The thrust bearing is removed entirely, eliminating the components that are subject to wear and sticking, thereby improving the reliability and maintenance-free operation of the pump system
Solution Approach 2:
The hydraulic pressure differential mechanism replaces the mechanical bearing system, using fluid pressure to balance axial forces without any moving parts or contact surfaces that would generate wear or sticking, thereby significantly improving reliability
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 eliminates the need for axial bearings, reduces friction and volumetric losses, ensures stable operation across varying conditions, and provides a compact, cost-effective solution with reduced maintenance needs.
Implementation Method 1
an axial throttling gap with a variable gap width on an inner diameter of the impeller. This sealing gap is traversed by radial inwards and forms an axial throttle, the effect of which depends on the gap width of the axial gap, which in turn depends on the axial position of the impeller
Implementation Method 2
a relief bore that opens between the inner diameter and the shaft into the wheel side chamber, thereby allowing flow through the wheel side chamber, thus enabling the radial and axial sealing gaps to become effective
Implementation Method 3
A radial sealing gap (radial gap) with a constant gap width on an outer diameter of the impeller. This sealing gap forms a radial pre-throttle and is traversed by axial flow
Data Source
Figure 1~3
Figure 4
AI summary
The invention relates to a wet rotor pump (1) with a permanent magnet rotor (2) and a pump chamber (4) bounded from the rotor (2) by a partition (5), in which an impeller (7) is arranged. The impeller is mounted non-rotatably on an axially displaceable shaft (3) and has a support disk (8), a cover disk (10), and blades (9) arranged between them. The cover disk (10) is radially sealed by means of a suction neck seal (11), and a first annular wall (12) projects from the support disk (8). This annular wall, together with an axial projection (6) of the partition (5), forms an axially flowable, radial throttle gap (13) of constant width. A relief bore (18) forms a fluid connection between the suction side (20) of the impeller (2) and an impeller side chamber located between the support disk (8) and the partition (5).The impeller (7) has a second annular wall (14) extending towards the partition (5), which divides the impeller side space between the first wall (12) and the shaft (3) into a radially outer annular space (16) and a radially inner annular space (17). Together with the partition (5), this annular wall forms a radially flowable axial throttling gap (15) that depends on the axial position of the impeller (7). The suction neck seal (11) is located on a diameter between the radial throttling gap (13) and the axial throttling gap (15). The relief bore (18) opens into the radially inner annular space (17). As a result of this design, the gap width of the axial throttling gap (15), and thus the axial position of the impeller, adjusts itself automatically. Therefore, a thrust bearing is not required in the wet rotor pump (1).