Bypass dart and assembly

Abstract

A plunger assembly for down-hole use in a well. In one embodiment, the plunger assembly comprises a plunger having a first and second end, a cage attached to the second end of the plunger, and a dart disposed within the cage having a body with at least two surfaces, where one surface is a raised surface relative to the other, lower surface.

What is claimed is: 
     
         1 . A plunger assembly, comprising:
 (a) a plunger having a first and second end;   (b) a cage attached to the second end of the plunger; and   (c) a dart disposed within said cage having a body with at least two surfaces, where one surface is a raised surface relative to the other, lower surface.   
     
     
         2 . The plunger assembly of  claim 1  wherein the dart is slidably mounted in the cage so that the dart can be positioned in at least an open or closed position relative to the second end of the plunger. 
     
     
         3 . The plunger assembly of  claim 2  wherein the cage includes a clutch to retard movement of the dart between its open and its closed position. 
     
     
         4 . The plunger assembly of  claim 3  wherein the body of the dart is disposed between an upper end of the dart and a lower end of the dart. 
     
     
         5 . The plunger assembly of  claim 4  wherein the clutch exerts more force on the raised surface of the body of the dart than it does on the lower surface of the body of the dart. 
     
     
         6 . The plunger assembly of  claim 5  wherein the raised and lower surfaces of the body of the dart are positioned relative to one another so that the clutch exerts less force on the body of the dart when the dart is in its open and/or closed position. 
     
     
         7 . The plunger assembly of  claim 6  wherein the body of the dart has a circular cross-section and the diameter of the raised surface is greater than the diameter of the lower surface. 
     
     
         8 . The plunger assembly of  claim 7  wherein the clutch comprises one or more c-clips. 
     
     
         9 . The plunger assembly of  claim 7  wherein the clutch comprises one or more o-rings. 
     
     
         10 . The plunger assembly of  claim 9  wherein the cage includes only one set of threads, which connect the cage to the second end of the plunger. 
     
     
         11 . A plunger assembly, comprising:
 (a) a plunger having a first and second end;   (b) a cage attached to the second end of the plunger; and   (c) a dart disposed within said cage having a body with at least three surfaces, where two surfaces are raised surfaces relative to the third, lower surface.   
     
     
         12 . The plunger assembly of  claim 11  wherein the cage includes at least one channel that allows gases or liquids to pass from inside the cage to outside the cage. 
     
     
         13 . The plunger assembly of  claim 12  further comprising a gap between a lower end of the dart and a lower end of the cage that allows gases or liquids to flow through the gap and out the at least one channel in the cage. 
     
     
         14 . A dart for a plunger assembly wherein the dart comprises:
 (a) an upper end and a lower end;   (b) a main channel that runs from the lower end toward the upper end; and   (c) a diversion channel that intersects the main channel and provides a passage from an interior of the dart to an exterior.