Patent ID: 6401843
Filing Date: 2002-06-11
Classification: E21B,F16C,F16J

Abstract:
A drilling head, comprising:a cone rock bit, each cone including: a stationary part including a pressure-compensating system configured to deliver a lubricating product at a desired back pressure to compensate for apressure of a drilling matter; a rotary part configured to rotate about an axis of rotation; and a dynamic sealing device borne by the rotary part and being disposed between the stationary part and the rotary part, and configured to avoid an ingress of drilling matter under said pressure of the drilling matter, and said sealing device including: a first sealing lip having an outer face facing toward said drilling matter and an inner face facing toward a cavity which forms a reservoir of the lubricating product; and a second sealing lip having an outer face facing toward an outlet of the pressure compensating system at said back pressure and an inner face facing toward said cavity, wherein the first and second lips form a surface of revolution about said axis of rotation, and respectively bear against a first bearing face and a second bearing face secured to the stationary part, wherein the first lip is oriented in such a way that it presses against the first bearing face under the action of the pressure of the drilling matter, and wherein the second lip is oriented in such a way that it moves away from the second bearing face under the action of said back pressure of the lubricating product, so as to allow the lubricating product to fill the cavity at said back pressure thereby compensating for the pressure in the cavity.