Research On Eccentric Load Problem Of Permanent Magnet Motor Direct-drive Submersible Progressive Cavity Pump

Because of the characteristics of structure,motion and cooperation of progressive cavity pump,the stator will produce the large deformation under high inner pressure,the deformation will be more serious under differential pressure,the large deformation of stator will aggravate the eccentric motion of progressive cavity pump.The eccentric motion of progressive cavity pump will lead to the stator of progressive cavity pump with submersible motor shaft can't coordinated concentric operation,at the same time,there is a certain eccentricity between the progressive cavity pump and submersible motor shaft,and the eccentricity is particularly harmful to the fatigue life of submersible motor shaft,the progressive cavity pump is equivalent to the eccentric load of submersible motor in submersible progressive cavity pump system.Therefor,researching the motion of progressive cavity pump,the deformation law and the stress and strain distribution of stator's inner-contour,the influence of eccentric motion of progressive cavity pump on the fatigue life of submersible motor shaft and the compensation measures of eccentric motion of progressive cavity pump have the vital practical significance,it can not only improve the fatigue life of submersible motor shaft,but also improve the efficiency and service life of submersible progressive cavity pump production system,which is beneficial to further promote the oil extraction technology of the submersible progressive cavity pump.In this paper,the progressive cavity pump and submersible motor shaft are taken as the object of study.Explored the eccentric mechanism of progressive cavity pump,included the principle of working,structure and cooperation,and calculated the profile equations of stator and rotor.And then,explored the motion of rotor in the stator,summarized the motion law of core of section and points on the surface of rotor in the stator.Made the parametric entity model of rotor and stator by the 3D modeling software,and completed the assembly and interference checking,verified the correctness of established model.And then made the static analysis of structures for progressive cavity pump's stator and contact analysis between the stator and rotor by the finite element software,summarized the deformation law,the stress and strain distribution of stator's inner-contour line under different working pressure.Made the finite element analysis for stress and fatigue cycle times of submersible motor shaft under different eccentricity by the finite element software,researched the influence of eccentric motion of progressive cavity pump on the fatigue life of submersible motor shaft,summarized the relationship between the eccentricity caused by eccentric motion of the progressive cavity pump and the stress and fatigue life of submersible motor shaft.In view of the eccentric motion of progressive cavity pump,put forward two kinds of compensation measures of eccentric motion.One was that made optimization design for progressive cavity pump's structure,changed the progressive cavity pump to the convex stator progressive cavity pump,and made the finite element analysis for improved progressive cavity pump,compared the results of the improved and the original one,explored whether the improved progressive cavity pump could compensate the eccentric motion of progressive cavity pump to some extent,reduced the eccentricity between the progressive cavity pump and submersible motor shaft,achieved the effect of compensation.The other was that installed a harmonic compensation device between the progressive cavity pump and submersible motor,compensated the eccentricity between the progressive cavity pump and submersible motor shaft,made the progressive cavity pump with submersible motor shaft can coordinated concentric operation.The end,compared and analysed the compensation device existing in the market,selected the most suitable compensation device for this paper.