Patent GB-991460-A (GB)
Title: Torque-transmitting rotary drive fluid conduit connection
IPC: F16D3/76
Filed: 1961-08-21
Abstract: 991,460. Securing together rotary parts; resilient couplings; pipe joints. DRILCO OIL TOOLS Inc. Aug. 21, 1961 [Aug. 31, 1960; Aug. 9, 1961], No. 30122/61. Headings F2G and F2U. In drill strings for rotary drilling of oil and gas wells, a resilient rotary drive fluid conduit connection between a drill bit 11 and a collar member 12 comprises a rubber insert, such as 16, Fig. 1, bonded by vulcanization to a pipe, such as 14, Fig. 1, secured to the collar member or, as shown, the bit, and to a tube, such as 15, Fig. 1, secured to the bit or, as shown, the collar member, and facial dog clutch teeth, such as 19a, 19b, Fig. 1, are provided on the pipe and tube respectively so that in the event of failure of the rubber insert the tube (or pipe) may be lowered to effect engagement of the teeth 19a, 19b and enable drilling torque to be transmitted between the pipe and the tube. In Fig. 1, the rubber insert 16 moulded in situ comprises circumferentially spaced arcuate portions extending axially from an annular portion which latter provides a seal against axial fluid flow. The teeth 19b are formed internally on a nipple 17a which is screwed inside the tube 15 and engages the periphery of a pipe enlargement 17b to provide transverse locating means, similar locating means, not shown, being provided at the upper end of the connection. Relative axial travel of the pipe and tube is limited by engagement of the teeth 19a, 19b at one end and abutment shoulders, not shown, adjacent the upper locating means. In Figs. 3A, 3B, a rubber sleeve 24, preferably of neoprene rubber, bonded to a pipe 23 and a tube 45, comprises rectangular, trapezoidal or circular cross-section, substantially axial holes 47 formed by core-rods held in place during injection of the rubber, and fillets 51, 51<SP>1</SP> to prevent excessive shrinkage stresses. The outer and inner peripheries of the pipe and tube respectively are correspondingly coned (e.g. “ in. per foot), the rubber sleeve being of constant wall thickness. At the upper end of the connection, transverse location is provided by a ring 58 screwed into the tube 45 which ring has a bore 62 making a sliding fit with the periphery 30 of a nipple 20 screwed into the pipe 23. A stop comprised by the upper edge 61 of the ring and an abutment 32 on the nipple 20 limit relative axial travel in one direction between the pipe and tube. Alternatively separate location and stop rings may be provided. Sealing means preventing axial fluid flow comprises a seal ring 36 of rubber compound reinforced with canvas which is held against an abutment 34 on the nipple 20 by a spring clip-retained dished plate 37. The seal ring 36 engages a liner 71 pressed or shrunk into a connecting member 46 which is screwed into the tube 45 and has a recess or, as shown, a spigot 70 for screw connection with the collar member. The seal ring and liner are replaceable or the seal ring may be moulded in situ. At the lower end of the connection transverse location is provided by a nipple 52 screwed into the tube 45 which nipple has a bore 53<SP>1</SP> making a sliding fit with a pipe enlargement surface 26 which, together with the periphery 30 may have wear resistant hard metal bands. Venting of spaces 63, 56 between the pipe and tube is respectively through the holes 47 and a hole 55. Facial dog clutch teeth 80, 83, which also serve to limit relative axial travel in the other direction, are provided respectively on the nipple 52 and on a pipe enlargement 82 which latter has a spigoted or, as shown, recessed portion 22 for screw connection with the drill bit. The fluid seal and transverse location means permit relative axial movement between the pipe and tube to enable clutch engagement whilst maintaining the fluid seal and the stability of the connection in the event of failure of the rubber sleeve. In both embodiments, the downwardly acting fluid (mud) pressure axially pre-loads the rubber insert so that if the bit rises due to a hard spot in the hole the sleeve relaxes instead of the shock being transmitted to the collar member.