Rotor Orbit Control in Moving Cavity Motors
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Solution Overview
Problem
In moving cavity motors and pumps, the deformation of the flexible stator surface due to forces acting on the rotor leads to gap formation between the rotor and stator, reducing flow rate, pressure, and torque output.
Innovation Solution
The implementation of apparatuses such as wheel assemblies, fixed inserts, and precession devices to constrain and limit the movement of the rotor relative to the stator, minimizing deformation and gap formation by controlling the rotational and positional movement of the rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the flexible stator surface deforms under forces acting on the rotor, then the rotor can rotate within the stator, but gap formation occurs between rotor and stator reducing flow rate, pressure, and torque output
Solution Approach 1:
The patent applies preliminary anti-action by using spring-loaded pistons that continuously apply a counteracting force to maintain the stator surface in contact with the rotor. The springs are pre-loaded to exert a force that opposes the gap-forming forces, ensuring continuous contact and preventing leakage paths before they can form during operation.
Solution Approach 2:
The patent implements dynamics by using movable pistons with spring mechanisms that can dynamically adjust to varying operational conditions. The pistons move radially to maintain contact pressure between the stator and rotor regardless of changes in rotational speed, load, or thermal expansion, ensuring continuous adaptation to maintain seal integrity.
2Reliability
If the stator surface is made flexible to maintain seals, then sealing is improved, but rotor position control becomes difficult leading to orbit issues
Solution Approach 1:
The patent introduces an intermediary control system consisting of position-sensing devices that monitor rotor location and control mechanisms that adjust stator-rotor spacing. This intermediary system mediates between the flexible stator surface and the rotor, providing active position control while maintaining seal integrity through controlled compliance.
3Productivity
If apparatus are added to constrain rotor movement, then gap formation is reduced, but device complexity increases
Solution Approach 1:
The patent merges the gap-prevention function with the existing rotor support structure by integrating spring-loaded pistons into the rotor housing. The constraining apparatus is combined with the drive shaft assembly, eliminating the need for separate external constraint mechanisms and reducing overall device complexity while maintaining productivity.
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 solution enhances the performance of moving cavity motors and pumps by maintaining seal integrity, increasing flow rate, pressure, and torque output while reducing wear and leakage.
Implementation Method 1
at least one apparatus comprising a spring-loaded piston arranged to act on the stator to minimise a gap between the rotor and the stator
Implementation Method 2
There is also a centrifugal force generated by the orbital motion of the rotor
Data Source
AI summary
Techniques involve a motor assembly including a rotor and a stator. The stator includes a contact surface for contacting an outer surface of the rotor. The contact surface includes a rigid material. The motor assembly also includes at least one constraint disposed along a length of the motor assembly, where the constraint constrains a radial and/or tangential movement of the rotor relative to the stator. The at least one constraint may be disposed at one or more proximate ends of the motor assembly, and/or along the length of the motor assembly. The contact surface of the stator may have a profile including peaks and valleys, and in some embodiments, the contact surface may be treated to reduce friction and/or wear.