Adjustable interference progressive cavity pump/motor for predictive wear

Abstract

Various examples are provided for progressive cavity pumps and motors. In one example, among others, a progressive cavity pump (or motor) includes a stator having a hyperboloidal internal bore including a plurality of spiral lobes, and a rotor comprising a plurality of spiral lobes positioned within the hyperboloidal internal bore of the stator. A longitudinal axis of the rotor is non-planar, non-parallel, and non-intersecting with a longitudinal axis of the stator. The stator can include an elastomeric material coating the hyperboloidal internal bore of the stator, which can reduce the effect of friction and abrasion during operation. The elastomeric material can include fluoro-based elastomers, other elastomeric materials or combinations thereof. For example, a fluoromonomer such as tetrafluoroethylene (TFE) or a fluoropolymer such as polytetrafluoroethylene (PTFE) can be used. The rotor can be configured to allow for displacement to adjust an interference fit between the rotor and the stator.

Therefore, at least the following is claimed: 
     
         1 . A progressive cavity pump, comprising:
 a stator having a hyperboloidal internal bore including a plurality of spiral lobes; and   a rotor comprising a plurality of spiral lobes positioned within the hyperboloidal internal bore of the stator, where a longitudinal axis of the rotor is non-planar, non-parallel, and non-intersecting with a longitudinal axis of the stator.   
     
     
         2 . The progressive cavity pump of  claim 1 , wherein the longitudinal axis of the rotor is offset from the longitudinal axis of the stator and rotated by a defined angle. 
     
     
         3 . The progressive cavity pump of  claim 2 , wherein the defined angle is in a range from about 0.001 degree to about 10 degrees. 
     
     
         4 . The progressive cavity pump of  claim 2 , wherein the longitudinal axis of the rotor is offset from the longitudinal axis of the stator by a defined distance. 
     
     
         5 . The progressive cavity pump of  claim 4 , wherein the defined distance is in a range from about 0.01 inch to about 10 inches. 
     
     
         6 . The progressive cavity pump of  claim 2 , wherein skew axes of the stator and rotor are non-planar, non-parallel, and non-intersecting. 
     
     
         7 . The progressive cavity pump of  claim 1 , wherein the rotor is tapered from a larger end to a smaller end. 
     
     
         8 . The progressive cavity pump of  claim 7 , wherein the taper of the rotor is hyperboloidal. 
     
     
         9 . The progressive cavity pump of  claim 1 , wherein the stator comprises an elastomeric material coating the hyperboloidal internal bore of the stator. 
     
     
         10 . The progressive cavity pump of  claim 9 , wherein the elastomeric material reduces the effect of friction and abrasion when operating under high temperature conditions. 
     
     
         11 . The progressive cavity pump of  claim 10 , wherein the elastomeric material comprises a fluoropolymer. 
     
     
         12 . The progressive cavity pump of  claim 11 , wherein the fluoropolymer is polytetrafluoroethylene (PTFE). 
     
     
         13 . The progressive cavity pump of  claim 10 , wherein the elastomeric material further comprises a filler component. 
     
     
         14 . The progressive cavity pump of  claim 13 , wherein the filler component comprises mullite, pyrophyllite, kyanite, dolomite, or a combination thereof. 
     
     
         15 . The progressive cavity pump of  claim 10 , wherein the elastomeric material has a coefficient of friction in the range of about 0.2 to about 0.4 and a wear rate of about 1×10 −7  mm 3 /Nm or less. 
     
     
         16 . The progressive cavity pump of  claim 1 , wherein the rotor is configured to allow for displacement to adjust an interference fit between the rotor and the stator. 
     
     
         17 . The progressive cavity pump of  claim 16 , wherein the rotor can be displaced along the longitudinal axis of the rotor.