Patent ID: 8069934
Filing Date: 2011-12-06
Classification: E21B

Abstract:
1. A device including a drill bit, said drill bit comprising: a predetermined number N of lug members arranged at a 360/N degree angle to each other and joined by an upper support member, each said lug member includes a lower journal portion and has a through vertical hole in an upper portion thereof; N bearings each externally and rotatably mounted on the journal portion of each said lug member, said bearings each fixedly supports a cutter member, whose longitudinal axis is positioned at a predetermined tilt angle to a horizontal line; a sleeve containing lubrication liquid and having a base mounted upon said upper support member and a bottom region; a central channel disposed within the sleeve, said central channel includes a lower portion outstanding below the sleeve's base and terminated with an opening controllably closed or opened with a reciprocating valve-plate; an annular piston capable to reciprocate in the bottom region of the sleeve, snug-fitting between the sidewalls of said sleeve and said channel, said piston is furnished with at least one discharge valve outletting the lubrication liquid through said piston at a predetermined reverse pressure; a spring disposed at the bottom region of said sleeve below said piston; N rods mounted in the bottom region of said sleeve and inserted through the holes of said lug members, the upper ends of said rods are coupled to said piston, and the lower ends of said rods are coupled to said valve-plate; and lubrication channels arranged in said lug members and communicating the bottom region of said sleeve under the piston with said bearings.