Down-hole mud actuated hammer

A down-hole mud actuated hammer for use in a drill string, said mud hammer comprising:

• a housing including an upper end with means for connecting to the drill string, and a lower end;
• a throat within the housing which includes a main flow passage to allow high pressure drilling mud to pass from the upper end of the housing to the lower end thereof;
• a shank slidably fitting within the lower end of the housing, the shank including a lower end with means for connecting to a drill string or drill bit, and having an upper end with impact surfaces;
• a piston adapted to move axially within the housing to thereby reciprocate between an up position and a down position, the piston including a lower end having impact surfaces adapted to strike the impact surfaces of the shank when the piston is in the down position;
• an upstroke chamber adapted so that when high pressure mud flows into the upstroke chamber, the high pressure mud contacts an upward actuating surface of the piston and thereby exerts an upward force on the piston;
• a down stroke chamber adapted so that when high pressure mud flows into the downstroke chamber, the high pressure mud contacts a downward actuating surface of the piston to thereby push the piston downward to the down position wherein the impact surfaces of the piston strike the impact surfaces of the shank;
• and
• a sliding valve adapted to slide between a first position wherein high pressure mud from the main flow passage is allowed to flow into the downstroke chamber, and a second position wherein the mud is exhausted from the downstroke chamber through an exhaust passage to a low pressure region out of the housing without being returned to the main flow passage.

A down-hole mud actuated hammer for use in a drill string, said mud hammer comprising:

• a housing including an upper end with means for connecting to the drill string, and a lower end;
• a throat within the housing which includes a main flow passage to allow high pressure drilling mud to pass therethrough;
• a shank slidably fitting within the lower end of the housing, the shank including a lower end with means for connecting to a drill string, and having an upper end with a plurality of impact surfaces;
• a piston disposed concentrically around the throat and adapted to move axially within the housing to thereby reciprocate between an up position and a down position, the piston including a lower end having a plurality of impact surfaces adapted to strike the impact surfaces of the shank when the piston is in the down position;
• an upstroke chamber adapted so that when a minor portion of the high pressure mud flows through a high pressure passage into the upstroke chamber, the high pressure mud contacts an upward actuating surface of the piston and thereby exerts an upward force on the piston;
• a downstroke chamber adapted so that when high pressure mud flows into the downstroke chamber, the high pressure mud contacts a downward actuating surface of the piston to thereby push the piston downward to the down position wherein the impact surfaces of the piston strike the impact surfaces of the shank;
• a sliding valve disposed concentrically around the piston with a gap therebetween to allow mud to flow between the upstroke chamber and the downstroke chamber, the sliding valve further comprising at least one high pressure supply port and at least one mud exhaust port;
• and
• a valve sleeve comprising high pressure mud supply passage and a mud exhaust passage;
• wherein the sliding valve is adapted to slide between a first position wherein high pressure mud is allowed to flow from the high pressure supply passage through the high pressure mud supply port into the downstroke chamber and wherein mud is not allowed to be exhausted from the downstroke chamber;
• and a second position wherein mud is allowed to flow from the downstroke chamber through the mud exhaust port, through the exhaust chamber to a low pressure region out of the housing without being returned to the main flow passage.