DOWNHOLE AIR HAMMER Russian patent published in 1996 - IPC

FIELD: hole drilling. SUBSTANCE: downhole hammer has body with adapter for connecting rod string on one end and adapting bushing with box for connecting drill bit on the other end. Body accommodates three-stage hollow piston-hammer which forms chambers of working and idle strokes and executes reciprocating motion. Stage diameter reduces towards striking end. Stage of small diameter has exhaust hole whose diameter equals 0.45-0.5 of the diameter of this stage. Middle stage has internal bore communicated with working stroke chamber. Diameter of stage with the largest diameter has internal bore communicated with idle stroke chamber. Diameter of bores equals 0.6-0.7 of diameter of respective stages of piston-hammer. EFFECT: higher efficiency. 1 dwg