Downhole percussion drilling apparatus

摘要

A downhole percussion drilling apparatus includes a housing and a piston rotatably supported within an interior bore of the housing. A first engagement surface serves as a cam surface. A second engagement surface serves as a follower surface. The cam surface has a plurality of inclined planes each of which terminates in a drop off. With each rotation of the piston, the follower surface rises up each of the inclined planes and then falls down each of the drop offs of the cam surface thereby imparting a series of percussive hammering impacts to the piston.