US 5,513,713 AGranted

Steerable drillhead

AssigneeThe United States of America as represented by the Secretary of the Navy

InventorFrank K. Groves

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Abstract

An apparatus for boring a continuous underground tunnel and located inside f the forward end of a continuously rotating, pushed drillstring includes a housing for receiving pressurized drilling fluid, a nozzle including bores, attached forwardly to the housing for discharging the pressurized drilling fluid from the nozzle, a rotatable valve located in said housing for receiving and forwardly directing pressurized drilling fluid from the housing to the nozzle. The valve may be rotated in a 1st position, thereby directing the pressurized drilling fluid to a first set of bores in the nozzle for boring straight ahead. The valve may also be rotated in a 2nd position, thereby directing the pressurized drilling fluid to a second set of bores. By maintaining the valve in the 1st position for 1/4 rotation of each revolution of the drillstring and then maintaining the valve in the 2nd position for the remaining 3/4 rotation of each revolution of the drillstring, an off axis (curved) tunnel may be bored.

Claims7

Dependent claims

An apparatus for boring a continuous underground tunnel, the apparatus located in the forward end of a continuously rotating, pushed drillstring, comprising:

a) a housing for receiving pressurized drilling fluid;
b) a nozzle attached forwardly to the housing, the nozzle having 1st, 2nd, 3rd and 4th bores for discharging the pressurized drilling fluid;
c) a valve located in said housing, the valve having 1st, 2nd, 3rd and 4th bores for receiving and forwardly directing said pressurized drilling fluid simultaneously to at least two bores in said nozzle, the valve rotatable to a first position to allow said pressurized drilling fluid to be discharged from said nozzle to bore a tunnel straight ahead or said valve rotatable to a first position during part of each revolution of said drillstring and rotatable to a second position during the remaining part of each revolution of said drillstring to allow said pressurized drilling fluid to be discharged from said nozzle to bore an off-axis tunnel, the 1st, 2nd and 3rd bores in said valve and in said nozzle communicate when said valve is in the first position and said 1st, 2nd and 4th bores in said valve and in said nozzle communicate when said valve is in the second position,
d) means for sealing said nozzle in said drillstring.

1 more element

Dependencies are inferred from the claim text.