Hammer drills for making boreholes

A valveless-type down-the-hole hammer drill which has an inner tube extending from the upper end of the hammer body into a central opening in a cutter bit reciprocably mounted in a chuck on the opposite end of the hammer body. High pressure fluid is supplied to the interior of the inner tube and a piston surrounding the inner tube has internal surfaces controlling connection of a port to chambers above and below the piston. The external surface of the piston controls connection of these chambers to an exhaust port. A valve sleeve on the chuck coacts with the piston in this respect.

I claim:

1. A valveless down-the-hole hammer drill for use with a drill string supplying high pressure fluid to the hammer drill, comprising:

a body tube having an upper end for attachment to a drill string;

a chuck secured to said body tube at a lower end thereof;

a cutter bit carried by said chuck;

cooperating means on said chuck and said cutter bit mounting said cutter bit for limited axial movement relative to said chuck;

a piston within said body tube reciprocable axially therein into percussive contact with said cutter bit and defining with said body tube upper and lower chambers at opposite ends of said piston;

supply control means cooperable with said piston and responsive to axial movement thereof for selectively connecting said upper and lower chambers and the pressure fluid supply from the drill string according to the axial position of said piston in said body tube;

an exhaust port;

exhaust control means cooperable with said piston and responsive to axial movement thereof for selectively connecting said upper and lower chambers to said exhaust port according to the axial position of the piston in said body tube;

said exhaust control means including a foot valve sleeve mounted on said chuck surrounded by an annular space in communication with said exhaust port;

said piston being reciprocable between a raised position in which pressure fluid is supplied to the upper chamber, the lower end of the piston is clear of the foot valve sleeve, and said lower chamber is connected to said exhaust port through said annular space whereby the piston is urged downwardly and a lower position in which pressure fluid is supplied to the lower chamber, the lower end of the piston is sealingly engaged in the foot valve sleeve to seal the lower chamber from the exhaust port, and the upper chamber is connected to the exhaust port whereby the piston is urged upwardly.

2. A hammer drill according to claim 1 wherein said foot valve sleeve extends axially upwardly from said chuck into said lower chamber, said supply control means including means for supplying pressure fluid into said sleeve when said piston lies in said lower position thereof in sealing engagement with the foot valve sleeve.

3. A hammer drill according to claim 1 wherein said cutter bit includes means defining a central passageway, an inner tube carried by the drill string, a sample tube within said inner tube and defining with said inner tube an annular space therebetween in communication with the pressure fluid supply from the drill string, means defining with said sample tube an annular nozzle disposed within said central passageway and arranged to direct fluid flowing through said annular space between said inner tube and said sample tube upwardly into the lower end of said sample tube.

4. A hammer drill according to claim 3 wherein said nozzle is formed by a fluid flow reversing device carried by said cutting bit and including a tubular portion extending into the lower end of said sample tube.

5. A hammer drill according to claim 4 in which said tubular portion extends into the lower end of said sample tube a distance greater than the width of the annular space formed between the tubular portion and the sample tube.

6. A valveless down-the-hole hammer drill for use with a dual-wall drill string, comprising:

a body tube for attachment at one end to the drill string;

a lining tube mounted co-axially in the body tube, said lining tube having supply ports therein;

an annular hammer piston mounted between the body tube and the lining tube for axial reciprocation relative thereto and in part defining upper and lower chambers;

a cutter bit;

means mounted said cutter bit on the opposite end of the body tube for limited axial displacement relative thereto;

means including said lining tube defining a high pressure fluid supply passage for conveying pressure fluid for driving the hammer piston from the drill string to said supply ports in the lining tube and alternatively to said upper and lower chambers in response to axial reciprocation of said piston;

an annular foot valve sleeve fixedly mounted in the body tube adjacent said opposite end thereof;

means defining an exhaust port adjacent said opposite end of the body tube and alternately in communication with said upper and lower chambers in response to axial reciprocation of said piston;

said hammer piston being reciprocable between a raised position in which pressure fluid is applied to said upper chamber via said supply ports, said piston is axially spaced from said foot valve sleeve, and communication between the supply ports and the exhaust port is blocked by engagement between the piston and said lining tube, and a lowered position in which fluid pressure is applied to said lower chamber via said supply ports and the lower end of the piston is in engagement with said foot valve sleeve to block communication between said supply ports and said exhaust port;

whereby said piston is caused to reciprocate and deliver repeated blows to the cutter bit.

7. A hammer drill according to claim 6 wherein said cutter bit has a axial passageway, a sample tube within said lining tube and defining with said lining tube an annular space therebetween, means defining with said lining tube an annular nozzle disposed within said axial passageway and arranged to direct pressure fluid flowing through said annular space between said sample tube and said lining tube upwardly into the lower end of said sample tube.

8. A hammer drill according to claim 7 wherein said nozzle is formed by a fluid flow reversing device carried by said cutting bit and including a tubular portion extending into the lower end of said sample tube.

9. A hammer drill according to claim 8 in which said tubular portion extends into the lower end of said sample tube a distance greater than the width of the annular space formed between the tubular portion and the sample tube.

10. A waveless down-the-hole hammer drill for use with a dual-wall drill string, comprising:

a body tube for attachment at one end to the drill string,

a lining tube mounted co-axially in the body tube, said lining tube having supply ports therein;

a sample tube mounted in the lining tube;

an annular hammer piston carried by the drill between the body tube and the lining tube for axial reciprocation relative thereto and, in part, defining upper and lower chambers in alternate communication with said supply ports in response to axial reciprocation of said piston;

a cutter bit;

means mounting said cutter bit adjacent the opposite end of said body tube for limited axial displacement relative thereto;

said lining tube and said sample tube being shaped and dimensioned to define between them a high pressure fluid supply passage for conveying pressure fluid for driving the hammer piston from the drill string to said supply ports in the lining tube and alternately to said upper and lower chambers;

an annular foot valve sleeve fixedly mounted in said body tube adjacent said opposite end thereof; an exhaust port located at said opposite end of the body tube;

said hammer piston being reciprocable between a raised position in which pressure fluid is applied to said upper chamber via said supply ports, said piston is axially spaced from said foot valve sleeve, and communication between the supply ports and the exhaust port is blocked by engagement between the piston and said lining tube, and a lowered position in which fluid pressure is applied to said lower chamber via said supply ports and the lower end of the piston is in engagement with said foot valve sleeve to block communication between said supply ports and said exhaust port;

whereby said piston is caused to reciprocate and deliver repeated blows to the cutter bit;

an annular flushing nozzle located within said passageway of the cutter bit for directing flushing fluid upwardly into the sample tube;

said lining tube and said sample tube being further shaped and dimensioned to provide passageway connecting said pressure fluid supply passage to the flushing nozzle for supplying pressure fluid to said flushing nozzle.

11. A valveless down-the-hole hammer drill for use with a drill string supplying high pressure fluid to the hammer drill, comprising:

a body tube having an upper end for attachment to a drill string;

a chuck secured to said body tube at a lower end thereof;

a cutter bit carried by said chuck;

cooperating means on said chuck and said cutter bit mounting said cutter bit for limited axial movement relative to said chuck;

a piston within said body tube reciprocable axially therein into percussive contact with said cutter bit and defining with said body tube upper and lower chambers at opposite ends of said piston;

supply control means cooperable with said piston and responsive to axial movement thereof for selectively connecting said upper and lower chambers and the pressure fluid supply from the drill string according to the axial position of said piston in said body tube;

an exhaust port;

exhaust control means cooperable with said piston and responsive to axial movement thereof for selectively connecting said upper and lower chambers to said exhaust port according to the axial position of the piston in said body tube;

said exhaust control means including a foot valve sleeve fixedly mounted in said body tube adjacent the lower end thereof;

said piston being reciprocable between a raised position in which pressure fluid is supplied to the upper chamber, the lower end of the piston is clear of the foot valve sleeve, and said lower chamber is connected to said exhaust port whereby the piston is urged downwardly and a lower position in which pressure fluid is supplied to the lower chamber, the lower end of the piston is sealingly engaged in the foot valve sleeve to seal the lower chamber from the exhaust port, and the upper chamber is connected to the exhaust port whereby the piston is urged upwardly.