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 for a dart plunger wherein the dart includes a shaft having a first end, a second end, and where the shaft has a diameter that varies between the first end and the second end. 
     
     
         2 . The dart of  claim 1  wherein the shaft further includes an intervening region between the first end and the second end, where the intervening region has a larger diameter than the diameter of the shaft toward its first and second end. 
     
     
         3 . The dart of  claim 2  further including a head at a terminal end of the first end for preventing flow through a dart plunger when the dart is in a closed position and for allowing flow through the dart plunger when the dart is in an open position. 
     
     
         4 . The dart of  claim 3  wherein the head has a diameter greater than the diameter of the intervening region. 
     
     
         5 . The dart of  claim 4  further including a tail at a terminal end of the second end, where the tail has a diameter substantially equal to the diameter of the intervening region. 
     
     
         6 . The dart of  claim 5  wherein the diameter of the shaft at the first end, the intervening region, and the second end is sized to allow the first end, the intervening region, and the second end to pass through a clutch in a dart plunger. 
     
     
         7 . The dart of  claim 6  wherein the diameter of the head is sized to not allow the head to pass through a clutch in a dart plunger. 
     
     
         8 . The dart of  claim 7  wherein the diameter of the shaft at the first end is sized to create less frictional force when passing through a clutch in a dart plunger than when the intervening region passes through the clutch in the dart plunger. 
     
     
         9 . The dart of  claim 8  wherein the diameter of the shaft at the second end is sized to create less frictional force when passing through a clutch in a dart plunger than when the intervening region passes through the clutch in the dart plunger. 
     
     
         10 . The dart of  claim 9  wherein the diameter of the shaft at the first end is substantially equal to the diameter of the shaft at the second end. 
     
     
         11 . The dart of  claim 10  wherein the dart is a single piece forged from a single component.