Bumper assembly having progressive rate spring

Abstract

A bumper assembly for down-hole use in a well. In one embodiment, the bumper assembly includes a fish neck, a cage, and a progressive rate spring disposed there-between. When a plunger strikes the top of the fish neck, the progressive rate spring dampens the force delivered by the plunger, thereby prolonging the useful life of the plunger and/or the bumper assembly.

What is claimed is: 
     
         1 . A bumper assembly, comprising:
 (a) a first end;   (b) a second end; and   (c) a progressive rate spring disposed between said first and said second end.   
     
     
         2 . The bumper assembly of  claim 1  further comprising a pull rod attached to said first end and engaged with said second end. 
     
     
         3 . The bumper assembly of  claim 2  wherein the pull rod is slideably engaged with said second end. 
     
     
         4 . The bumper assembly of  claim 3  wherein at least a portion of said pull rod is enclosed by said progressive rate spring. 
     
     
         5 . The bumper assembly of  claim 4  wherein said first end includes a fish neck. 
     
     
         6 . The bumper assembly of  claim 5  wherein said second end includes a cage. 
     
     
         7 . The bumper assembly of  claim 6  wherein a portion of the second end is attached to a well pipe. 
     
     
         8 . The bumper assembly of  claim 7  wherein said cage includes a device for dampening a force delivered to said device by said pull rod. 
     
     
         9 . The bumper assembly of  claim 8  wherein said device for dampening comprises a Belleville washer. 
     
     
         10 . A bumper assembly for use down-hole in a well, comprising:
 (a) a fish neck;   (b) a cage; and   (c) a progressive rate spring disposed between said fish neck and said cage.   
     
     
         11 . The bumper assembly of  claim 10  further comprising an extension for attaching to the cage, where said extension also attaches to a well pipe or the bottom of the well. 
     
     
         12 . The bumper assembly of  claim 11  further comprising a pull rod attached to said fish neck and engaged with said cage. 
     
     
         13 . The bumper assembly of  claim 12  wherein the pull rod is slideably engaged with said cage. 
     
     
         14 . The bumper assembly of  claim 13  wherein at least a portion of said pull rod is enclosed by said progressive rate spring. 
     
     
         15 . The bumper assembly of  claim 14  wherein said cage includes a device for dampening a force delivered to said device by said pull rod. 
     
     
         16 . The bumper assembly of  claim 15  wherein said device for dampening comprises a Belleville washer.