Patent ID: 9657528
Date: 2017-05-23
CPC Classifications: E21B

Claim:
1. An earth boring bit comprising: a bit body; at least one bearing shaft mounted to the bit body; a rotary cutter mounted for rotation on the bearing shaft, defining an intermediate space located there-between; a seal disposed between the bearing shaft and the rotary cutter for sealing the intermediate space from an exterior of the bit; a flow passage extending through said bit body, from an interior cavity of the bit body to said intermediate space located between the bearing shafts and the rotary cutters; a compensator having a first end disposed in communication with said flow passage and a second end disposed in communication with the interior cavity; at least one aperture extending between an interior of said compensator and said flow passage; and a moveable seal member disposed in said interior of said compensator for at least initially being disposed in a first position, biased to apply pressure to a lubricant disposed in said flow passage and prevent fluid flow through a flow path extending between said interior cavity of the bit body and said flow passage, and wherein said moveable seal member is disposed in a second position within said compensator when the lubricant is expelled from said compensator and when disposed in said second position said moveable seal member is located aside of said flow path for passing fluid flow from said interior cavity of the bit body to said flow passage below the compensator.