Replaceable Thermoplastic Stator for Positive Displacement Motor
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Solution Overview
Problem
Existing Positive Displacement Motors (PDMs) have limited service range due to stator materials being degraded by high temperatures, acids, solvents, gases, and entrained solids, and are often disposable once worn, lacking reusability and compatibility in harsh environments.
Innovation Solution
A PDM design featuring a thermoplastic stator, such as polyether ether ketone (PEEK), that is resistant to high temperatures, acids, gases, and solvents, and can be easily removed and replaced, allowing for prolonged use and improved reusability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional stator materials are used in PDMs, then the motor can operate in standard conditions, but the service range is severely limited due to degradation from high temperatures, acids, solvents, gases, and entrained solids
Solution Approach 1:
The patent applies composite materials by combining a thermoplastic matrix (such as PEEK, polypropylene, or nylon) with reinforcing fibers (such as carbon fiber, glass fiber, or aramid fiber). This composite structure provides both the chemical resistance and mechanical strength required for harsh downhole environments, resolving the contradiction between adaptability to various corrosive conditions and reliability under stress.
Solution Approach 2:
The patent changes the material parameters by selecting thermoplastics with specific glass transition temperatures (Tg) and melting points suitable for different temperature ranges. By adjusting material composition and cross-linking density, the stator maintains flexibility and sealing properties across a wide temperature range from -50°C to 200°C, expanding service range while maintaining reliability.
2Duration of action of stationary object
If the stator is made from wear-resistant materials, then the tool life can be extended, but the stator becomes difficult to replace and the device is often disposable once worn
Solution Approach 1:
The patent segments the stator into a removable component that can be independently replaced from the motor housing. The stator is designed as a separate insert with retention features (such as O-rings, snap-fits, or threaded connections) that allow it to be easily removed and replaced without disposing of the entire motor assembly, thereby extending tool life through component reuse while maintaining ease of repair.
Solution Approach 2:
The patent implements a dynamic retention system where the stator can be securely held during operation but easily removed when needed. Retention mechanisms such as elastomeric O-rings, spring-loaded clips, or threaded fasteners allow the stator to remain fixed under operational stresses while enabling simple replacement by loosening retention features, resolving the contradiction between durability and replaceability.
3Adaptability or versatility
If the stator material is made compatible with harsh chemicals and high temperatures, then the service range is improved, but the material selection and manufacturing complexity increases
Solution Approach 1:
The patent achieves universality by selecting thermoplastic materials (such as PEEK, polypropylene, or nylon) that provide broad-spectrum resistance to multiple corrosive agents including acids, solvents, and bases, while also withstanding high temperatures. These multi-functional materials eliminate the need for different stator materials for different chemical environments, simplifying manufacturing and material selection while maintaining wide chemical compatibility.
Data Source
AI summary
A positive displacement motor (PDM) is provided comprising an outer housing, a thermoplastic stator and a rotor. The PDM may additionally include a mechanism that allows the stator to be removable from the PDM when the PDM is not in operation and resists rotational movement of the stator with reference to a longitudinal axis of the stator and axial movement of the stator along the longitudinal axis of the stator when the PDM is operating, and a rotor disposed within the stator and configured to rotate within the stator when a fluid flows through the stator.