Uniaxial Eccentric Screw Pump Variable Interference Design
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Solution Overview
Problem
Existing uniaxial eccentric screw pumps face challenges in achieving tight sealing while reducing the driving force required to rotate the rotor, as excessive interference leads to high torque and sealing issues, while insufficient interference compromises sealing tightness.
Innovation Solution
The design incorporates a stator with an elongated insertion hole and a rotor that performs eccentric rotation, with a cross-sectional center displaceable in a reciprocating manner. The interference amount between the rotor and stator is greater in the end areas for sealing and smaller in the middle area to reduce rotational force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the interference amount between rotor and stator is increased to improve sealing tightness, then sealing performance is improved, but the driving force required to rotate the rotor increases
Solution Approach 1:
The patent applies different interference amounts at different axial positions of the rotor-stator interface. Specifically, the insertion hole has a first interference amount in the end areas (first and second axial directions) and a second interference amount in the middle area, where the first interference amount is greater than the second. This local differentiation ensures tight sealing at the ends where it is most critical while reducing friction and driving force requirements in the middle section.
2Force
If the interference amount is decreased to reduce driving force, then rotational efficiency is improved, but sealing tightness deteriorates
Solution Approach 1:
The patent implements variable interference distribution along the axial direction of the rotor. The insertion hole is designed with a first interference amount in the end areas and a second interference amount in the middle area, creating a gradient structure. This allows the system to maintain adequate sealing at the ends while reducing overall friction and driving force requirements through the reduced interference in the middle section.
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 configuration maintains tight sealing in the end areas while reducing the driving force needed to rotate the rotor in the middle area, effectively balancing sealing integrity and rotational efficiency.
Implementation Method 1
The rotor performs eccentric rotation about a central axis of the stator
Implementation Method 2
An interference amount between the rotor and the stator includes a first interference amount when the cross-sectional center is at one of the pair of turn positions and a second interference amount when the cross-sectional center is at the central axis
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 being externally threaded and placed through the insertion hole. In a cross section, the rotor has a cross-sectional center displaceable in a reciprocating manner in a longitudinal direction of the insertion hole between a pair of turn positions along a center line extending in the longitudinal direction during eccentric rotation of the rotor. The rotor comes in contact with the inner peripheral surface of the insertion hole in a lateral direction of the insertion hole. An interference amount between the rotor and the stator includes a first interference amount when the cross-sectional center is at one of the turn positions and a second interference amount when the cross-sectional center is at a central axis. The first interference amount is larger than the second interference amount.