BIASED LUBRICANT COMPENSATOR FOR AN EARTH BORING DRILL BIT

摘要

An improved pressure compensator for earth boring drill bits for minimizing the pressure differential between the lubricant and the well bore. A flexible diaphragm is located in the lubricant reservoir for separating the lubricant from the borehole fluid. The diaphragm is positioned in the reservoir so that a substantial void space exists on the borehole fluid side of the reservoir. A retainer holds the diaphragm in this position, requiring a positive lubricant pressure to stretch the diaphragm in order to fill the void space. For lubricating the bit, the lubricant is introduced under pressure sufficient to stretch the diaphragm. The lubricant pressure is then released, allowing the compensator to return to its original shape which in turn causes the excess lubricant to be expelled. This assures complete filling and a desired void space.