Thrust face lubrication system for a rolling cutter drill bit

(19)

(11)

EP 0 699 816 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	07.05.1997 Bulletin 1997/19

(43)	Date of publication A2:
	06.03.1996 Bulletin 1996/10

(21)	Application number: 95305970.6

(22)	Date of filing: 25.08.1995

(51)	International Patent Classification (IPC)⁶: E21B 10/24

(84)	Designated Contracting States:
	DE GB IT NL

(30)

Priority:

31.08.1994 GB 9417496

(71)	Applicant: CAMCO INTERNATIONAL INC.
	Houston, Texas 77054 (US)

(72)	Inventor:
	Daly, Jeffery E. Cypress, Texas 77429 (US)

(74)	Representative: Carter, Gerald
	Arthur R. Davies & Co. 27 Imperial Square Cheltenham, Gloucestershire GL50 1RQ Cheltenham, Gloucestershire GL50 1RQ (GB)

(54)	Thrust face lubrication system for a rolling cutter drill bit

(57) A rolling cutter drill bit comprises a main body (12) and three depending legs (14), each leg having a cantilevered bearing spindle (16) on which a rolling cutter (18) is rotatably mounted. Bearings located between the cutter and spindle include a radial bearing (36), and a thrust bearing (44) configured to carry onward thrust loads from the cutter onto the spindle. A bearing seal (32) defines an enclosed region between the cutter and the spindle in which the bearings are located, and a pressure balanced lubricant delivery system (22,24,26) within the spindle delivers lubricant to the bearings. The lubricant delivery system includes a non-return valve (50,52) to allow lubricant to flow into the area of the enclosed region containing the thrust bearing (44) and the area is bounded by a tortuous flow path (56) which allows a more restricted flow of lubricant out of the thrust bearing area and into another area of the enclosed region, without pressurising the bearing seal (32). The non-return valve (50,52) may be replaced by a flexible barrier ring (62) in the tortuous path which deflects to allow a greater flow of lubricant into the thrust bearing area.

Search report