PNEUMATIC DRILL HAMMER COMPRISING A BOOST CHAMBER AND A DRILLING RIG COMPRISING SUCH A DRILL HAMMER

摘要

The invention relates to a pneumatically operated drill hammer, comprising a piston and a distributor axially arranged relative each other in a housing, the piston being arranged to be moved axially between a first position and a second position. The drill hammer further comprises a pneumatic drive system, comprising a drive chamber, a return chamber and a plurality of channels for distribution of drive gas in said drive system. The return chamber is arranged at a lower side of the piston and the drive chamber is arranged at an upper side of the piston, wherein the drive chamber is defined by a variable space enclosed by at least the housing, the piston and the distributor. The drive chamber comprises at least one inlet port and at least one exhaust port arranged at a circumference of the drive chamber, wherein pressurization of the pneumatic drive system alternates pressurization of the drive chamber and the return chamber, wherein the piston moves back and forth between the first and second position. Furthermore, the piston comprises a first inner surface, and the distributor comprises a second inner surface, said first and second inner surfaces being arranged to align adjacent each other when the piston moves towards the first position, wherein said alignment divides the drive chamber into a sub-drive chamber and at least one boost chamber, said at least one boost chamber being separated from the inlet and the exhaust port. The invention further relates to a drill hammer in the form of a Down-The-Hole-, DTH-, hammer, and a drilling rig, comprising such a drill hammer.