BUILT-IN MECHANISM FOR ATTENUATING TORSIONAL VIBRATIONS FOR OIL FIELD DRILLING TOOL Russian patent published in 2018 - IPC E21B17/04 E21B17/07 

FIELD: oil and gas industry.

SUBSTANCE: downhole tool for attenuating torsional vibrations comprises a free-wheeling coupling assembly adapted to connect the drill string to a drill bit and engage for transmitting torque from said drill string to said drill bit in a first rotation direction of the drill string and disconnecting to prevent torque transmission from said drill string to said drill bit in a second rotation direction of the drill string opposite to said first direction. Said free-wheeling coupling assembly comprises a coupling housing having a generally tubular shape and defining an inner wall with a groove of a tapered shape therein, a coupling mandrel, on one axle located inside said coupling housing and defining the outer wall with a recess made therein, a wedge-shaped element inserted into said recess and forced radially outward up to contact with said inner wall of said coupling housing. Said wedge-shaped element is being adapted to come into contact with said recess to prevent unrestricted rotation of said coupling body relative to said coupling mandrel in the first direction and disconnecting from said groove for providing unrestricted rotation of said coupling housing with respect to said coupling mandrel in the second direction opposite to the first direction.

EFFECT: providing torsional vibrations without the need to increase the bit rate or decrease the weight on the bit.

18 cl, 15 dwg