Segmented Eccentric Screw Rotor Coupling Element
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Solution Overview
Problem
The existing coupling elements for helix-shaped eccentric screw pump rotors are complex and costly to produce due to the need for precise machining and tight tolerances, and they often require specialized sections for receiving the drive shaft end.
Innovation Solution
A coupling element with a hollow cylindrical design featuring inner circumferential surfaces of varying radii, including a larger radius surface section for increased tolerance, and radial bores for securing elements like grub screws, allowing for easier production and assembly without rework, and enabling secure attachment of the rotor end without precise machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the coupling element uses an uninterrupted helix-shaped inner wall surface complementary to the rotor end, then the rotor end can be properly guided and secured, but the manufacturing complexity and cost increase due to precision machining requirements
Solution Approach 1:
The uninterrupted helix-shaped inner wall surface is segmented into multiple discrete helical ridges or nubs. This segmentation maintains the guiding function by providing multiple contact points for the rotor end while significantly reducing manufacturing complexity, as the segmented structure can be produced by casting or simpler machining processes rather than requiring precision machining of a continuous surface.
Solution Approach 2:
Instead of providing a complete uninterrupted helical surface throughout the coupling element, the helical guiding surfaces are provided only at specific locations where contact with the rotor end is needed. This local quality approach maintains guiding precision at critical points while reducing overall manufacturing complexity and material requirements.
2Manufacturing precision
If the coupling element requires precision machining of the entire inner circumferential surface, then accurate rotor guidance is achieved, but production time and cost increase
Solution Approach 1:
The inner circumferential surface is segmented into discrete helical contact points rather than requiring a complete precision-machined surface. This segmentation allows the majority of the surface to be produced by faster casting or forming processes, while only small specific areas require precision machining, thereby significantly increasing production speed while maintaining adequate guiding accuracy.
3Reliability
If the coupling element uses a complex helical profile throughout, then proper rotor coupling is achieved, but material usage and manufacturing cost increase
Solution Approach 1:
The helical profile is segmented into discrete ridges or nubs rather than a continuous helical structure. This segmentation reduces material consumption by eliminating unnecessary material in non-contact areas while maintaining coupling reliability through the strategic placement of helical contact points that provide adequate guiding and securing functions.
Solution Approach 2:
The unnecessary portions of the helical profile are extracted or removed, leaving only the essential helical contact points needed for rotor guidance and securing. This extraction reduces material consumption while preserving the core functional requirements of the coupling element.
Data Source
AI summary
A coupling element for connecting a helix-shaped eccentric screw pump rotor to a drive shaft, with a drive shaft receiving portion and a rotor connecting portion arranged at an opposite end of the coupling element from the drive shaft receiving portion, the rotor connecting portion is constituted as a hollow cylinder for receiving a rotor end of the screw pump rotor, wherein the hollow cylinder has at least two inner circumferential surfaces which are complementary to the rotor and have a radius which is fixed with respect to the cross-sectional center of the hollow cylinder.