Wet Rotor Pump Assembly Centring via Bearing Retainer
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Solution Overview
Problem
Existing wet rotor pumps in house heating systems face challenges in achieving a compact design while maintaining precise coaxial alignment of the rotor axis with the pump housing, leading to inefficiencies due to manufacturing tolerances and increased fluid leakage.
Innovation Solution
The pump assembly incorporates a rotor can flange with a radial distance to the pump housing, utilizing a bearing retainer for sliding contact and centring, along with radial projections for exact alignment, and a resilient bearing retainer flange for axial positioning, minimizing the gap between the impeller and neck ring to enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the rotor can is directly centred by the pump housing using circumferentially distributed trunnions, then the alignment precision is improved, but the lateral space requirement increases due to the large rotor can flange
Solution Approach 1:
The patent introduces a bearing retainer as an intermediary component between the pump housing and the rotor can. The bearing retainer has a bearing retainer flange that abuts against the pump housing and provides centring surfaces that radially centre the rotor can with respect to the pump housing. This intermediary structure enables precise coaxial alignment without requiring a large rotor can flange, thus resolving the contradiction between alignment precision and lateral space requirement
Solution Approach 2:
The patent segments the centring function into separate components: the bearing retainer handles the centring of the rotor can, while the pump housing provides structural support. This segmentation allows the rotor can flange to be smaller since it only needs to accommodate the bearing retainer interface, not direct mounting to the pump housing, thereby reducing lateral space while maintaining alignment precision
2Reliability
If the gap between the impeller and neck ring is increased to accommodate manufacturing tolerances, then the reliability of rotation is improved, but the pumping efficiency decreases due to fluid leakage
Solution Approach 1:
The bearing retainer acts as an intermediary centring mechanism that reduces the impact of manufacturing tolerances on the gap between the impeller and neck ring. By providing precise radial centring surfaces, the bearing retainer ensures that the rotor axis remains accurately positioned, allowing the gap to be minimized for high pumping efficiency while still accommodating normal manufacturing variations. This resolves the contradiction by enabling reliable rotation with a smaller gap through improved centring precision
3Area of stationary object
If the rotor can flange is made smaller for compact design, then the lateral space is reduced, but the alignment capability with respect to the pump housing is worsened
Solution Approach 1:
The bearing retainer serves as a mediating component that transfers the centring function from the pump housing to a dedicated structure. The bearing retainer flange provides mounting surfaces for the bearing rings and centring surfaces for the rotor can, enabling accurate coaxial alignment even with a smaller rotor can flange. This intermediary structure resolves the contradiction by decoupling the alignment capability from the size of the rotor can flange
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 design achieves a more compact and efficient pump assembly by reducing manufacturing tolerances and fluid leakage, improving the alignment and resilience to pressure shocks, thereby increasing pumping efficiency.
Implementation Method 1
a first radial bearing ring (47) being in sliding contact with the rotor axle (45)
Data Source
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AI summary
The present disclosure is directed to a pump assembly (1) comprising - a rotor axle (45) extending along a rotor axis (R), - an impeller (12) fixed to the rotor axle (45), - a pump housing (11) accommodating the impeller (12), wherein the pump housing (11) defines a first radial inner reference surface (71), - a drive motor comprising a stator (17) and a rotor (51), wherein the rotor (51) is fixed to the rotor axle (45) for driving the impeller (12), - a rotor can (57) accommodating the rotor (51), wherein the rotor can (57) comprises a rotor can flange (63), - a stator housing (13) accommodating the stator (17), - a first radial bearing ring (47) being in sliding contact with the rotor axle (45), and - a bearing retainer (41) embracing the first radial bearing ring (47) and centring the first radial bearing ring (47) with respect to the first radial inner reference surface (71) of the pump housing (11). The rotor can flange (63) has a radial distance to the pump housing (11) and the rotor can (57) comprises a radial inner centring surface (65) being centred by radially abutting against a radial outer centring surface (67) of the bearing retainer (41).