The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 28, 1996
Filed:
May. 31, 1995
John D Barr, Cheltenham, GB;
Richard E Thorp, Frampton-Cotterell, GB;
Robert A Russell, Barnwood, GB;
Camco Drilling Group Limited, Stonehouse, GB;
Abstract
A modulated bias unit, for controlling the direction of drilling of a rotary drill bit when drilling boreholes in subsurface formations, comprises a number of hydraulic actuators spaced apart around the periphery of the unit, each having a movable thrust member which is hydraulically displaceable outwardly for engagement with the formation of the borehole being drilled. A selector control valve modulates the fluid pressure supplied to each actuator in synchronism with rotation of the drill bit so that, as the drill bit rotates, each movable thrust member is displaced outwardly at the same selected rotational position so as to bias the drill bit laterally and thus control the direction of drilling. The control valve is a disc valve comprising two relatively rotating elements having contiguous surfaces formed of polycrystalline diamond. The elements are maintained in coaxial relation by a polycrystalline diamond bearing pin which extends axially from one element and engages in a central axial bearing aperture in the other element.