Dart and clutch assembly

Abstract

Described herein are embodiments of systems and apparatuses that include a dart and/or a clutch for a dart plunger. In an exemplary embodiment, the clutch consists of a one-piece unit having a length, an outside diameter, and an inside diameter where at least a portion of the inside diameter is sized to create a frictional interface with a dart. The clutch may also include a gap, a slot, and/or a spiral cut. The dart may include a shaft having opposite ends and a shaft diameter that varies between the opposite ends.

1 . A dart plunger, comprising:
 a dart having a first position in the dart plunger and a second position in the dart plunger, wherein the dart is configured in the dart plunger to move between its first and second position;   a clutch retarding movement of the dart between its first and second position, wherein the clutch is a one-piece unit having a length, an outside diameter, and an inside diameter, where at least a portion of the inside diameter is sized to create a frictional interface with the dart; and   wherein the clutch further includes a gap extending from the outside diameter to the inside diameter along the entire length of the clutch.   
     
     
         2 . The dart plunger of  claim 1  wherein the first position of the dart is an open position. 
     
     
         3 . The dart plunger of  claim 2  wherein the second position of the dart is a closed position. 
     
     
         4 . The dart plunger of  claim 3  wherein the gap extending from the outside diameter to the inside diameter along the entire length of the clutch gives the clutch a c-shape. 
     
     
         5 . The dart plunger of  claim 4  wherein the inside diameter of the clutch is shaped so the entire inside diameter does not create the same frictional interface with the dart. 
     
     
         6 . The dart plunger of  claim 5  wherein the inside diameter of the clutch includes an undulating surface so the entire inside diameter does not create the same frictional interface with the dart. 
     
     
         7 . The dart plunger of  claim 6  wherein the inside diameter of the clutch includes at least one groove. 
     
     
         8 . The dart plunger of  claim 7  wherein the inside diameter of the clutch includes at least two grooves. 
     
     
         9 . The dart plunger of  claim 8  wherein the inside diameter of the clutch includes a surface between the at least two grooves for creating at least a portion of the frictional interface with the dart. 
     
     
         10 . The dart plunger of  claim 9  wherein the surface between the at least two grooves of the clutch has a radial curvature substantially equal to a radius of the dart. 
     
     
         11 . The dart plunger of  claim 10  wherein at least one of the grooves of the clutch extends along the entire length of the clutch. 
     
     
         12 . The dart plunger of  claim 11  wherein a center point of the outside diameter of the clutch is not the same as a center point of the inside diameter of the clutch. 
     
     
         13 . The dart plunger of  claim 12  wherein a center point of the outside diameter of the clutch is not the same as a center point of the inside diameter of the clutch, such that a sidewall of the clutch opposite the gap is thicker than a sidewall of the clutch near the gap. 
     
     
         14 . The dart plunger of  claim 13  where the outside diameter of the clutch is less than an inside diameter of a bore in the dart plunger. 
     
     
         15 . The dart plunger of  claim 14  wherein the outside diameter of the clutch is less than an inside diameter of a nut in the dart plunger. 
     
     
         16 . The dart plunger of  claim 4  wherein the inside diameter of the clutch is a variable inside diameter. 
     
     
         17 . The dart plunger of  claim 4  wherein the inside diameter of the clutch is shaped so the entire inside diameter does not create the same frictional interface with the dart. 
     
     
         18 . The dart plunger of  claim 4  wherein the inside diameter of the clutch includes an undulating surface so the entire inside diameter does not create the same frictional interface with the dart.