Progressive Cavity Pump Rotor-Stator Eccentricity Design
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Solution Overview
Problem
Conventional rotor-stator assemblies in progressive cavity pumps and positive displacement motors experience failures due to high centrifugal forces and heat retention issues, leading to elastomer degradation and increased manufacturing costs, with limited design configuration flexibility.
Innovation Solution
A rotor-stator assembly design with a stator housing having a cylindrical inner surface and a reduced eccentricity ratio (SD/Sd) of 1.350 or less, allowing for various lobe configurations, and an optional thinner elastomeric liner to minimize heat generation and retention, while maintaining manufacturing cost efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional rotor-stator assembly with high eccentricity is used, then the pump can handle viscous fluids effectively, but centrifugal forces increase causing heat generation and elastomer degradation
Solution Approach 1:
The patent changes the geometric parameter of the stator by reducing the eccentricity ratio (SD/Sd) to 1.350 or less, which directly reduces centrifugal forces and heat generation while maintaining fluid pumping capability through optimized lobe configurations
Solution Approach 2:
The patent applies different lobe configurations to different regions of the stator, allowing optimization of local flow characteristics while maintaining overall reduced eccentricity, thus balancing productivity with reduced harmful thermal effects
2Strength
If a thick elastomeric liner is used in the stator, then wear resistance is improved, but heat retention increases leading to elastomer degradation
Solution Approach 1:
The patent optimizes the thickness parameter of the elastomeric liner to achieve a balance between wear resistance and heat dissipation, preventing thermal degradation while maintaining mechanical durability
Solution Approach 2:
The patent may apply varying liner thickness or material properties in different regions of the stator to locally optimize for either wear resistance or thermal management depending on the specific operational requirements
3Adaptability or versatility
If various lobe configurations are implemented, then design flexibility is improved, but manufacturing complexity increases
Solution Approach 1:
The patent designs a universal stator structure with reduced eccentricity that can accommodate multiple lobe configurations (such as 3-lobe, 4-lobe, 5-lobe arrangements) through standardized manufacturing processes, enabling design flexibility without proportionally increasing manufacturing complexity
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 reduces centrifugal forces, heat generation, and elastomer heat retention, extending the life of the elastomeric liner and lowering manufacturing costs while allowing for flexible lobe configurations.
Implementation Method 1
high centrifugal forces and heat retention issues, leading to elastomer degradation
Implementation Method 2
heat generation, and elastomer heat retention
Implementation Method 3
heat retention issues, leading to elastomer degradation
Data Source
AI summary
Disclosed is a progressive cavity device. In some embodiments, the device includes a stator with an inner surface having a number of lobes and a rotor disposed within the stator and having a different number of lobes. The stator lobes define a major diameter and a minor diameter, where the major diameter circumscribes the stator lobes and the minor diameter inscribes the stator lobes. A rotor-stator, defined as the major diameter divided by the minor diameter, is selected from the group consisting of 1.350 or less for a progressive cavity device with a stator having two lobes, 1.263 or less for three lobes, 1.300 or less for four lobes, 1.250 or less for five lobes, 1.180 or less for six lobes, 1.175 or less for seven lobes, 1.150 or for eight lobes, 1.125 or less for nine lobes, and 1.120 or less for ten lobes.