Rock bit lubrication system

摘要

A sealed, pressure-equalizing lubrication system for a rotary rock bit is shown. The system includes a lubricant-filled container having an outlet and a portion of the container includes a flexible diaphragm. The container is mounted in a chamber in the journal axle portion of the bit, immediately adjacent and open to the sealed bearing cavity of the bit cutter, with the outlet disposed adjacent the cavity. A bleed hole is provided from the back face of the bit to the chamber adjacent the diaphragm causing the diaphragm to be responsive to the pressure of the external downhole fluid. The adjacency of the reservoir to the sealed bearing cavity permits the pressure of the lubricant adjacent the seal to be immediately responsive to the pressure of the downhole fluid at the diaphragm to prevent pressure differentials between the lubricant and the fluid at the seal.