Earth boring bit lubricant chamber barrier member with dispersed fibers

Abstract

An earth boring bit has a body with a depending bearing pin. A cone mounts rotatably on the bearing pin, the cone having cutting elements on its exterior. A lubricant chamber supplies lubricant to the bearing surfaces between the bearing pin and the cone. A barrier in the lubricant chamber has one side exposed to the exterior of the bit for contact by drilling fluid. The barrier member is elastomeric and contains chopped organic polymer fibers. The barrier member may be a seal ring between the cone and bearing pin, or it may be a lubricant compensator.

1 . An earth boring bit, comprising: 
 a bit body having a threaded upper end for connection to a drill string and at least one depending bearing pin;    a cone mounted on the bearing pin for rolling engagement with a bottom of a well bore as the body rotates;    a lubricant chamber in the body and the bearing pin for containing a lubricant; and    a barrier in the lubricant chamber having one side exposed to the exterior of the bit for contact by drilling fluid in the well bore for preventing entry of drilling fluid into the lubricant chamber, the barrier comprising an elastomeric material containing non-woven, non-cellulose fibers dispersed therein.    
   
   
       2 . The bit according to  claim 1 , wherein the barrier comprises a seal ring deformed between an inner diameter portion of the cone and an outer diameter portion of the bearing pin.  
   
   
       3 . The bit according to  claim 1 , wherein the barrier comprises a pressure compensator diaphragm that flexes to reduce pressure differential between the drilling fluid in the well bore and the lubricant in the lubricant chamber.  
   
   
       4 . The bit according to  claim 1 , wherein the bit has a seal assembly between the bearing pin and the cone comprising: 
 a rigid ring that engages an annular seal surface in dynamic sliding contact;    an elastomeric energizer ring that is deformed between an outer diameter portion of the bearing pin and the rigid ring to urge the rigid ring into contact with the annular seal surface, and wherein the barrier comprises:    an excluder ring deformed between a portion of the bearing pin and the rigid ring.    
   
   
       5 . The bit according to  claim 1 , wherein the fibers are formed of a material from the group consisting essentially of aromatic polyamide, polyimide, non-aromatic polyamide, polyurethane and polyester.  
   
   
       6 . The bit according to  claim 1 , wherein the fibers comprise less than five percent of the elastomeric material, by volume, of the barrier.  
   
   
       7 . The bit according to  claim 1 , wherein the fibers are dispersed uniformly throughout the barrier.  
   
   
       8 . The bit according to  claim 1 , wherein the fibers are randomly oriented in the barrier.  
   
   
       9 . In an earth boring bit having at least one cone rotatably mounted to a bearing pin and a seal assembly located between the bearing pin and the cone, the seal assembly comprising: 
 a barrier ring formed of a rubber compound and having randomly oriented, uniformly dispersed chopped fibers therein, the fibers being formed of a material from the group consisting essentially of aromatic polyamide, polyimide, non-aromatic polyamide, polyurethane and polyester.    
   
   
       10 . The bit according to  claim 9 , wherein the barrier ring comprises a seal ring having a surface in dynamic sliding contact as the cone rotates on the bearing pin.  
   
   
       11 . The bit according to  claim 9 , wherein the seal assembly comprises: 
 a metal ring that has an end face in dynamic engagement with an annular seal surface;    an elastomeric energizer ring that urges the metal ring into engagement with the annular seal surface; and wherein the barrier ring comprises:    an excluder ring deformed against the metal ring and having one side exposed to the exterior of the bit.    
   
   
       12 . The bit according to  claim 9 , wherein the barrier ring has a hardness in the range from 40-90 Shore A.  
   
   
       13 . The bit according to  claim 9 , wherein the fibers comprises less than five percent of the volume of the barrier ring.  
   
   
       14 . The bit according to  claim 9 , wherein the fibers are randomly oriented.  
   
   
       15 . An earth boring bit, comprising: 
 a bit body having at least one bearing pin depending thereform;    a cone rotatably mounted on the bearing pin;    a lubricant chamber containing a lubricant and defined by a cavity in the bit body, clearances between the cone and the bearing pin, and a passage between the cavity and the clearances; and    a barrier that blocks drilling fluid surrounding the bit body from entry into the lubricant chamber, the barrier being a rubber compound containing chopped polymeric fibers randomly dispersed throughout the barrier.    
   
   
       16 . The bit according to  claim 15 , wherein the polymeric fibers are formed from a material selected from the group consisting essentially of aromatic polyamide, polyimide, non-aromatic polyamide, polyurethane and polyester.  
   
   
       17 . The bit according to  claim 15 , wherein the barrier comprises a seal ring deformed between an inner diameter portion of the cone and an outer diameter portion of the bearing pin.  
   
   
       18 . The bit according to  claim 15 , wherein the barrier comprises a pressure compensator diaphragm that flexes to reduce pressure differential between the drilling fluid in the well and the lubricant in the lubricant chamber.  
   
   
       19 . The bit according to  claim 15 , wherein the bit has a seal assembly between the bearing pin and the cone comprising: 
 a rigid ring that engages an annular seal surface;    an energizer ring that is deformed between an outer diameter portion of the bearing pin and the rigid ring to urge the rigid ring into contact with the annular seal surface, and wherein the barrier comprises:    an excluder ring deformed between a portion of the bearing pin and the rigid ring.