Patent ID: 8215419

Claim:
A variable frequency down hole drill, comprising: a supply of motive fluid in the form of a compressible fluid; an exhaust structure communicating with the atmosphere; a drill bit; a reciprocating piston supported for reciprocation with respect to the drill bit; a drive chamber above the piston; a return chamber below the piston; means for driving reciprocation of the piston by alternatingly placing the drive chamber in communication with the supply of motive fluid and the return chamber in communication with the exhaust structure in a first instance and placing the drive chamber in communication with the exhaust structure and the return chamber in communication with the supply of motive fluid in a second instance; means for generating a command signal; and means for changing, in response to the command signal, the frequency with which the piston delivers impact loading to the drill bit; wherein the drill bit, piston, drive chamber, return chamber, and means for driving reciprocation comprise a drilling assembly adapted for operation at the bottom of a hole being drilled; and wherein the means for generating a command signal and the means for changing the frequency physically reside on the drilling assembly and are functional while the drilling assembly is down the hole.