Uniaxial Eccentric Screw Pump Elliptical Stator Profile
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Solution Overview
Problem
Existing uniaxial eccentric screw pumps face challenges in adjusting sealing tightness and driving force for rotating the rotor, leading to inappropriate fluid delivery due to varying interference amounts between the rotor and stator.
Innovation Solution
A uniaxial eccentric screw pump design featuring a stator with an elliptical insertion hole profile, where the interference amount between the rotor and stator is smaller in the middle area than in the two end areas, allowing for adjustable sealing tightness and reduced driving force requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the interference amount between rotor and stator is increased to improve sealing tightness, then sealing tightness is improved, but the driving force required to rotate the rotor increases
Solution Approach 1:
The insertion hole is designed with non-uniform interference distribution: larger interference amount at the two end areas to ensure sealing tightness, and smaller interference amount at the middle area to reduce friction and driving force requirements. This local differentiation resolves the contradiction between sealing and ease of rotation.
2Ease of operation
If the interference amount is decreased to reduce driving force, then ease of rotation is improved, but sealing tightness deteriorates
Solution Approach 1:
The insertion hole profile is designed to provide larger interference at the end areas where sealing is critical, while providing smaller interference at the middle area where rotation ease is more important. This spatially differentiated interference distribution simultaneously achieves both sealing tightness and ease of rotation.
3Ease of operation
If the opening profile is made more circular (higher minor/major diameter ratio) to improve rotor movement, then ease of rotation is improved, but fluid delivery capability deteriorates
Solution Approach 1:
The opening is designed with an elliptical profile where the minor diameter to major diameter ratio is controlled at 0.83 to 0.96. This asymmetric shape creates the necessary interference amount variation between end areas and middle area, enabling both proper rotor movement and effective fluid delivery through the smaller-volume cavities.
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 adjustable sealing tightness and reduced driving force for rotor rotation, ensuring reliable fluid delivery while optimizing operational efficiency.
Implementation Method 1
An interference amount between an outer peripheral surface of the rotor and the inner peripheral surface of the insertion hole in the stator is smaller in the middle area than in the two end areas
Data Source
AI summary
A uniaxial eccentric screw pump includes a stator having an insertion hole with an inner peripheral surface being internally threaded, and a rotor including shaft placed through the insertion hole in the stator. The insertion hole is, in a cross section, an opening including a middle area and two end areas. An interference amount between an outer peripheral surface of the rotor and the inner peripheral surface of the insertion hole in the stator is smaller in the middle area than in the two end areas.