Down-the-hole hammer with ported piston and flow control valve

A method for operating a down-the-hole hammer, the method comprising:

• supplying pressurized inlet air to an adapter of the down-the-hole hammer;
• opening a check valve to allow pressurized inlet air to flow through a control tube, through a piston, and into a distal chamber of a barrel of the down-the-hole hammer;
• flowing air from a proximal chamber of the barrel through the piston and a bore of a bit;
• sliding the piston proximally in response to a first pressure differential between the proximal chamber and the distal chamber;
• in response to a pressure increase in the proximal chamber, sliding a valve member proximally to open a flow path between the adapter and the proximal chamber;
• flowing air from a valve chamber through an air distributor into piston, and flowing air from the distal chamber through the bore of the bit;
• in response to a second pressure differential between the proximal chamber and the distal chamber, sliding the piston distally within barrel to impact the bit;
• and
• in response to the piston sliding distally in the barrel, sliding the valve member distally within barrel.

A down-the-hole hammer comprising:

• a barrel having a longitudinal axis and defining a proximal chamber and a distal chamber;
• a piston slidable within the barrel along the longitudinal axis in response to a pressure differential between the proximal chamber and the distal chamber;
• and
• a flow control valve providing selective fluid communication into the proximal chamber of the barrel,
• wherein the piston comprises:
• a proximal internal cavity;
• a distal internal cavity;
• at least one first port extending from the proximal internal cavity to an intermediate outer surface of the piston;
• at least one second port extending from the proximal internal cavity to a distal outer surface of the piston;
• and
• at least one third port extending from the distal internal cavity to the intermediate outer surface of the piston.