Self compensating adjustable fit progressing cavity pump for oil-well applications with varying temperatures
AssigneeWeatherford/Lamb, Inc.
InventorLonnie Dunn
Life of this patent
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Abstract
The present invention provides an adjustable rotor and/or stator, so that the interference fit and/or clearance can be adjusted. The rotor and/or stator are tapered to provide a difference in fit between the rotor and stator by longitudinal adjustment of their relative position. The relative longitudinal adjustment is achieved in response to a change in temperature and is matched to the taper angle of the stator/rotor to maintain a desired interference fit.
Claims45
A progressive cavity pump having a inlet and an outlet, comprising:
- a) a stator defining a bore tapered at an angle θ1 at least partially between the inlet and the outlet;
- and
- b) a rotor slidably disposed in the bore and tapered at an angle θ2 least partially between the inlet and the outlet;
- and
- c) a rod string connected to the rotor and having a length changing with temperature;
- wherein θ1 and θ2 are selected to maintain a predetermined fit between the stator and the rotor during the change in the length.
A progressive cavity pump having a inlet and an outlet, comprising:
- a) a stator carrying an elastomeric member on an inner surface, wherein the elastomeric member has a thickness and a thermal expansion coefficient and wherein a surface of the elastomeric member defines a bore having an increasing diameter along at least a portion of its length;
- and
- b) a rotor slidably disposed in the bore, wherein at least a portion of the rotor increases diametrically along its length and has an outer surface defining a taper angle θ, wherein the taper angle θ is selected to maintain a predetermined interference fit between the stator and the rotor during relative axial movement therebetween;
- and
- c) a rod string connected to the rotor and having a length that increases with an increasing temperature, whereby the rotor is axially moved relative to the stator when the stator is fixed in position;
- wherein the taper angle θ is determined according to at least the thermal expansion coefficient of the elastomeric member, the thickness of the elastomeric member, the length of the rod string and a thermal expansion coefficient of the rod string.
A progressive cavity pump, comprising:
- a) a stator defining a bore having a inlet and an outlet;
- and
- b) a rotor disposed in the bore and wherein the stator and the rotor define interfacing inclining surfaces adapted to move over one another and wherein the interfacing inclining surfaces are selected to define an interference fit that is maintained while the rotor is axially reciprocating within the bore in response to a change in an ambient temperature.
A method of adjusting a progressive cavity pump, comprising:
- a) providing a rotor slidably disposed in an opening of a stator, wherein the stator and rotor comprise interfacing inclined surfaces;
- and
- b) axially moving the rotor and the stator relative to one another as a function of temperature;
- and
- c) maintaining a desired interference fit between the interfacing inclined surfaces while performing step b).
Dependencies are inferred from the claim text.