Pneumatic drill hammer comprising a boost chamber and a drilling rig comprising such a drill hammer

A drilling rig comprising a drill line, at least one drill pipe, a source of drive gas, and at least one pump to control the drive gas,

• wherein the drill line comprises a drill hammer, the drill hammer comprises a piston and a distributor that are axially arranged relative to each other in a housing, the piston being arranged to be moved axially between a first position and a second position,
• wherein 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 the drive system, the return chamber being arranged at a lower side of the piston and the drive chamber being arranged at an upper side of the piston, wherein the drive chamber is positioned between the piston and the distributor, wherein the drive chamber is defined by a variable space enclosed by at least the housing, the piston, and the distributor, the drive chamber comprising 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 by means of the alternating pressurization of the drive chamber and return chamber,
• wherein the piston comprises a first inner surface, and the distributor comprises a second inner surface, the first inner surface and the second inner surface are arranged to align adjacent to each other in an event the piston moves towards the first position, wherein the alignment divides the drive chamber into a sub-drive chamber and at least one boost chamber, the at least one boost chamber being separated from the inlet port and the exhaust port, and
• wherein:
• at least one of the first inner surface and the second inner surface comprises a bevelled edge, arranged at a side of one of the at least first inner surface and the second inner surface, and
• the side is aligned with another of the at least first inner surface and the second inner surface to form a boost chamber in the event the piston moves towards the first position.

A pneumatically operated drill hammer comprising a piston and a distributor that are axially arranged relative to each other in a housing, the piston being arranged to be moved axially between a first position and a second position,

• wherein 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 the drive system, the return chamber being arranged at a lower side of the piston and the drive chamber being arranged at an upper side of the piston, wherein the drive chamber is positioned between the piston and the distributor, wherein the drive chamber is defined by a variable space enclosed by at least the housing, the piston, and the distributor, the drive chamber comprising 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 by means of the alternating pressurization of the drive chamber and return chamber,
• wherein the piston comprises a first inner surface, and the distributor comprises a second inner surface, the first inner surface and the second inner surface are arranged to align adjacent to each other in an event the piston moves towards the first position, wherein the alignment divides the drive chamber into a sub-drive chamber and at least one boost chamber, the at least one boost chamber being separated from the inlet port and the exhaust port, wherein a sidewall of the boost chamber comprises a hole in which an adjustable element is arranged to be selectively movable to adjust a volume of the hole, and wherein positioning of the adjustable element in the hole regulates an internal volume of the boost chamber, and
• wherein:
• at least one of the first inner surface and the second inner surface comprises a bevelled edge, arranged at a side of one of the at least first inner surface and the second inner surface, and
• the side is aligned with another of the at least first inner surface and the second inner surface to form a boost chamber in the event the piston moves towards the first position.