TORQUE LIMITER FOR DRILL STRING IN WELL Russian patent published in 2017 - IPC E21B17/04 E21B17/06 E21B17/07 

FIELD: mining.

SUBSTANCE: group of inventions relates to a device and a method of protecting a downhole tool connected to the drill string located in the well, where there are unfavourable conditions impeding rotational movement of the drilling assembly in the well. Torque limiter comprises a rotary inlet element having an inner cavity, herewith the inner cavity has a surface with multiple thrust seats, a rotary outlet element arranged inside the rotary inlet element inner cavity, multiple radial ratchet elements arranged radially between the rotary inlet element and the rotary outlet element, multiple bearings arranged radially between the multiple radial ratchet elements and the rotary outlet element, and a holding unit. Rotary outlet element contains multiple radial ledges and radial recesses. Each radial ratchet element has a radially inner surface and a radial outer surface containing at least one radially projecting thrust. Holding unit comprises a flexible element having sufficient flexibility force to maintain contact between the multiple ratchet elements, the multiple bearings and the second rotary element. Herewith each bearing, at least partially, is located between one of the radial ratchet elements and the rotary outlet element, and each thrust, at least partially, is located in an appropriate thrust seat. Second object is a method of limiting the torque in a rotary device including the torque limiter.

EFFECT: protection of a downhole tool from damages and breakages.

14 cl, 9 dwg