Enhanced PDM performance testing device

Abstract

A method for evaluating load performance of a rotor/stator test coupon, advantageously within a sealable test chamber comprising test fluid. In some embodiments, the test coupon comprises at least a partial length of a PDM stage, and in others the test coupon comprises a splined rotor/stator. The method includes rotating either the rotor section or the stator section, wherein such rotation actuates corresponding rotation of the other of the rotor section and the stator section. A braking torque is applied to the actuated one of the rotor section and the stator section such that load performance of the test coupon may be evaluated. Embodiments include selectively applying non-linear torque to load the test coupon, and evaluating load performance of the test coupon with reference to relative angular positions of the rotor section and the stator section over time.

We claim: 
     
       1. A method for evaluating load performance of a rotor/stator test coupon, the method comprising the steps of:
 (a) providing a test coupon, the test coupon including a splined rotor section received inside a splined stator section, wherein an exterior of the splined rotor section provides a plurality of rotor splines and an interior of the stator section provides a plurality of splined stator cutouts for receiving rotor splines; 
 (b) rotating a rotated first one of the splined rotor section and the splined stator section, wherein rotation of the rotated first one of the splined rotor section and the splined stator section actuates corresponding rotation of an actuated second one of the splined rotor section and the splined stator section; 
 (c) applying a braking torque to the actuated second one of the splined rotor section and the splined stator section; and 
 (d) responsive to step (c), evaluating load performance of the test coupon. 
 
     
     
       2. The method of  claim 1 , in which the splined rotor section rotates about a longitudinal rotor rotation axis and the splined stator section rotates about a longitudinal stator rotation axis, and in which step (b) includes setting a preselected offset distance between the rotor rotation axis and the stator rotation axis. 
     
     
       3. The method of  claim 1 , in which the splined rotor section rotates about a longitudinal rotor rotation axis and the splined stator section rotates about a longitudinal stator rotation axis, and in which the rotor splines are disposed parallel to the longitudinal rotor rotation axis and the splined stator section cutouts are disposed parallel to the longitudinal stator rotation axis. 
     
     
       4. The method of  claim 1 , in which step (d) includes at least one substep selected from the group consisting of:
 (d1) controlling torque across the splined rotor section and the splined stator section; 
 (d2) counting, through to failure of the test coupon, at least one of (1) splined rotor section rotation cycles and (2) splined stator section rotation cycles; and 
 (d3) examining at least one of (1) the splined rotor section and (2) the splined stator section for wear. 
 
     
     
       5. The method of  claim 1 , further comprising, after step (a) and before step (b), the substeps of:
 (a1) receiving the test coupon inside a sealable test chamber; 
 (a2) filling the test chamber with test fluid; and 
 (a3) sealing the test chamber. 
 
     
     
       6. The method of  claim 5 , in which step (d) further includes the substep of monitoring temperature change over time in the test chamber. 
     
     
       7. The method of  claim 1 , in which the splined stator section provides an elastomer interface at a contact surface with the splined rotor section inside the test coupon, and in which step (d) includes at least one substep selected from the group consisting of:
 (d1) controlling torque across the splined rotor section and the splined stator section; 
 (d2) counting, through to failure of the test coupon, at least one of (1) splined rotor section rotation cycles and (2) splined stator section rotation cycles; 
 (d3) examining at least one of (1) the splined rotor section and (2) the splined stator section for wear; and 
 (d4) monitoring temperature change over time in the elastomer interface. 
 
     
     
       8. The method of  claim 5 , in which the splined stator section provides an elastomer interface at a contact surface with the splined rotor section inside the test coupon, and in which step (d) further includes the substep of monitoring temperature change over time in the test chamber. 
     
     
       9. A method for evaluating load performance of a rotor/stator test coupon, the method comprising the steps of:
 (a) providing a test coupon, the test coupon including a rotor section received inside a stator section; 
 (b) rotating a rotated first one of the rotor section and the stator section with non-linear torque, wherein rotation of the rotated first one of the rotor section and the stator section actuates corresponding rotation of an actuated second one of the rotor section and the stator section; 
 (c) applying a braking torque to the actuated second one of the rotor section and the stator section; and 
 (d) responsive to step (c), evaluating load performance of the test coupon. 
 
     
     
       10. The method of  claim 9 , in which the non-linear torque in step (b) is delivered by at least one technique selected from the group consisting of:
 (1) engaging an impact hammer-pin clutch when rotating the rotated first one of the rotor section and the stator section; 
 (2) deploying a variable frequency drive motor to vary rotation speed of the rotated first one of the rotor section and the stator section; and 
 (3) variably applying a braking torque to the actuated second one of the rotor section and the stator section. 
 
     
     
       11. The method of  claim 9 , in which the rotor section rotates about a longitudinal rotor rotation axis and the stator section rotates about a longitudinal stator rotation axis, and in which step (b) includes setting a preselected offset distance between the rotor rotation axis and the stator rotation axis. 
     
     
       12. The method of  claim 9 , in which step (d) includes at least one substep selected from the group consisting of:
 (d1) controlling torque across the rotor section and the stator section; 
 (d2) counting, through to failure of the test coupon, at least one of (1) rotor section rotation cycles and (2) stator section rotation cycles; and 
 (d3) examining at least one of (1) the rotor section and (2) the stator section for wear. 
 
     
     
       13. The method of  claim 9 , in which the test coupon comprises at least a partial length of a positive displacement motor (PDM) stage. 
     
     
       14. The method of  claim 9 , in which, in step (a), at least one progressing gap on a helical pathway is formed between the rotor section and the stator section when the rotor section and the stator section are differentially rotated. 
     
     
       15. The method of  claim 9 , further comprising, after step (a) and before step (b), the substeps of:
 (a1) receiving the test coupon inside a sealable test chamber; 
 (a2) filling the test chamber with test fluid; and 
 (a3) sealing the test chamber. 
 
     
     
       16. The method of  claim 15 , in which step (d) further includes the substep of monitoring temperature change over time in the test chamber. 
     
     
       17. The method of  claim 9 , in which the stator section provides an elastomer interface at a contact surface with the rotor section inside the test coupon, and in which step (d) includes at least one substep selected from the group consisting of:
 (d1) controlling torque across the rotor section and the stator section; 
 (d2) counting, through to failure of the test coupon, at least one of (1) rotor section rotation cycles and (2) stator section rotation cycles; 
 (d3) examining at least one of (1) the rotor section and (2) the stator section for wear, and 
 (d4) monitoring temperature change over time in the elastomer interface. 
 
     
     
       18. The method of  claim 15 , in which the stator section provides an elastomer interface at a contact surface with the rotor section inside the test coupon, and in which step (d) further includes the substep of monitoring temperature change over time in the test chamber. 
     
     
       19. A method for evaluating load performance of a rotor/stator test coupon, the method comprising the steps of:
 (a) providing a test coupon, the test coupon including a rotor section received inside a stator section; 
 (b) rotating a rotated first one of the rotor section and the stator section, wherein rotation of the rotated first one of the rotor section and the stator section actuates corresponding rotation of an actuated second one of the rotor section and the stator section; 
 (c) applying a braking torque to the actuated second one of the rotor section and the stator section; 
 (d) during steps (b) and (c), independently monitoring at least one of (1) an angular position of the rotor section over time, and (2) an angular position of the stator section over time; and 
 (e) responsive to steps (b) through (d), evaluating load performance of the test coupon with reference to angular position as monitored in step (d) over time. 
 
     
     
       20. The method of  claim 19 , in which angular position in step (d) is monitored using at least one rotary encoder. 
     
     
       21. The method of  claim 19 , in which the rotor section rotates about a longitudinal rotor rotation axis and the stator section rotates about a longitudinal stator rotation axis, and in which step (b) includes setting a preselected offset distance between the rotor rotation axis and the stator rotation axis. 
     
     
       22. The method of  claim 19 , in which step (e) includes at least one substep selected from the group consisting of:
 (e1) controlling torque across the rotor section and the stator section; 
 (2) counting, through to failure of the test coupon, at least one of (1) rotor section rotation cycles and (2) stator section rotation cycles; and 
 (e3) examining at least one of (1) the rotor section and (2) the stator section for wear. 
 
     
     
       23. The method of  claim 19 , in which the test coupon comprises at least a partial length of a positive displacement motor (PDM) stage. 
     
     
       24. The method of  claim 19 , in which, in step (a), at least one progressing gap on a helical pathway is formed between the rotor section and the stator section when the rotor section and the stator section are differentially rotated. 
     
     
       25. The method of  claim 19 , further comprising, after step (a) and before step (b), the substeps of:
 (a1) receiving the test coupon inside a sealable test chamber; 
 (a2) filling the test chamber with test fluid; and 
 (a3) sealing the test chamber. 
 
     
     
       26. The method of  claim 25 , in which step (e) further includes the substep of monitoring temperature change over time in the test chamber. 
     
     
       27. The method of  claim 19 , in which the stator section provides an elastomer interface at a contact surface with the rotor section inside the test coupon, and in which step (e) includes at least one substep selected from the group consisting of:
 (e1) controlling torque across the rotor section and the stator section; 
 (e2) counting, through to failure of the test coupon, at least one of (1) rotor section rotation cycles and (2) stator section rotation cycles; 
 (e3) examining at least one of (1) the rotor section and (2) the stator section for wear; and 
 (e4) monitoring temperature change over time in the elastomer interface. 
 
     
     
       28. The method of  claim 25 , in which the stator section provides an elastomer interface at a contact surface with the rotor section inside the test coupon, and in which step (e) further includes the substep of monitoring temperature change over time in the test chamber.