Eccentric Screw Pump Stator with Varying Wall Thickness
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Solution Overview
Problem
Eccentric screw pump stators with conical linings face increased wear and reduced durability when handling coarse materials, and struggle to maintain optimal conveying capacity and medium stabilization due to uneven elastic resilience and pressure distribution.
Innovation Solution
A stator design with a varying average wall thickness, starting from a cylindrical suction side, decreasing to a minimum and then increasing again to form a cylindrical widening at the pressure side, allowing for a flexible transition and reduced wear, while maintaining a constant connection via flanges and optimizing medium transfer and retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the lining is tapered conically from the suction side to the discharge side to adapt elastic compliance to increasing discharge pressure, then the pumping capacity is improved, but the forces acting on the lining are increased causing faster wear when handling coarse materials
Solution Approach 1:
The lining is designed with spatially varying wall thickness: thinner in the high-pressure discharge region to reduce forces and wear, and thicker in the suction region to provide structural support and accommodate coarse materials. This local differentiation of properties resolves the contradiction between pumping capacity and durability.
Solution Approach 2:
The wall thickness parameter of the lining is continuously varied along the axial direction according to a specific function, transitioning from a minimum thickness in the discharge area to a greater thickness in the suction area. This parameter change optimizes both the elastic compliance for pressure adaptation and the structural integrity for handling coarse materials.
2Adaptability or versatility
If the lining wall thickness is reduced in the discharge area to reduce wear, then the elastic compliance is improved, but the structural strength and ability to handle high pressure differentials is reduced
Solution Approach 1:
The lining structure is optimized locally: the discharge area has reduced wall thickness for high elastic compliance and pressure adaptation, while the suction area has increased wall thickness for structural strength. This local quality differentiation allows each region to perform its specific function optimally without compromising overall strength.
Solution Approach 2:
The solution moves from a uniform one-dimensional wall thickness to a two-dimensional gradient structure where thickness varies continuously along the axial direction. This dimensional change allows simultaneous optimization of compliance in the discharge region and strength in the suction region.
3Adaptability or versatility
If a conical taper is used to adapt the lining to increasing discharge pressure, then a transition piece with constant wall thickness requires a specially adapted design, but this increases manufacturing complexity
Solution Approach 1:
The wall thickness parameter is defined as a continuous function of the axial position, allowing the lining to be manufactured as a single integrated component with gradually varying thickness. This eliminates the need for separate transition pieces with constant wall thickness and simplifies the overall manufacturing process.
Solution Approach 2:
The transition piece functionality is merged into the lining itself through the continuous wall thickness variation. The lining directly provides the pressure adaptation and geometric transition without requiring a separate component, reducing the number of parts and simplifying assembly.
4Reliability
If the lining becomes harder in the axial direction to prevent backflow, then the retention is improved, but the flexibility and ability to stabilize high-pressure medium is reduced
Solution Approach 1:
The lining hardness is differentiated spatially: the discharge area has higher hardness (thinner wall) to prevent backflow under high pressure differentials, while the suction area has lower hardness (thicker wall) to provide flexibility for medium stabilization and accommodate coarse materials. Each region's local property matches its functional requirements.
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 enhances the stator's durability and conveying capacity by adapting to pressure changes, reducing wear, and stabilizing the medium through distinct zones for premixing, high-pressure, and stabilization, allowing for efficient medium transfer and reduced backflow.
Implementation Method 1
a continuous, helical pump cavity formed by an elastomer lining
Data Source
Figure 1~1a
Figure 2~2b
Figure 3
AI summary
The invention relates to a stator (1) for an eccentric screw pump having a rotor, wherein the stator (1) has an elastically compliant lining (3) with an outer surface (9), wherein the lining (3) is enclosed by a rigid shell (2), wherein an inner surface (4) of the lining (3) forms a double-start steep thread and defines an axially extending (X) pump cavity (5) for receiving the rotor of the eccentric screw pump, wherein the lining (3) of the stator (1) tapers in the axial direction (X), wherein for this purpose an average wall thickness (W) of the lining (3) decreases continuously in the axial direction (X) from an end wall thickness (WE) which is present in the region of a suction side (7) of the stator (1) until a minimum average wall thickness (WM) is reached.According to the invention, it is provided that the mean wall thickness (W) of the lining (3) increases again at least in certain areas after reaching the minimum mean wall thickness (WM), so that an expansion (10) forms in the lining (3) up to a pressure side (8) of the stator (1).