Down-hole air hammer

Claim 2

In percussion drilling apparatus: an outer housing structure connectible to a drill string; an anvil in the lower portion of said housing structure and connectible to a drill bit; said housing structure including a first cylinder and a second cylinder therebelow of greater internal diameter than the internal diameter of said first cylinder; a hammer piston reciprocable in said cylinders for intermittently impacting against said anvil, said piston having an upper portion slidably reciprocable in said first cylinder and in sealed relation thereto and a lower portion of greater diameter than said upper portion slidably reciprocable in said second cylinder and in sealed relation thereto; said upper portion having an effective cross-sectional area substantially equal to the internal crosssectional area of said first cylinder; means for directing a fluid medium under pressure into said first cylinder above said upper piston portion for action upon the full effective crosssectional area of said upper piston portion and into said second cylinder above said lower piston portion for driving said hammer piston downwardly toward said anvil; and means for directing the fluid medium under pressure into a lower portion of said housing structure for action upon said hammer piston to elevate said hammer piston in said housing structure.

Claim 3

In apparatus as defined in claim 1; said structure having discharge ports communicating with the interior of said second cylinder through which fluid medium exhausts directly to the exterior of said structure after downward movement of said hammer piston along said first and second cylinders.

Claim 4

In apparatus as defined in claim 1; said second cylinder having discharge ports controlled by said lower piston portion through which fluid medium in said first cylinder above said upper piston portion and fluid medium in said second cylinder exhaust after downward movement of said hammer piston along said first and second cylinders.

Claim 5

In apparatus as defined in claim 1; said hammer piston shifting in said first and second cylinders to alternately control flow of the fluid medium into said lower portion of said housing structure and said first and second cylinders.

Claim 6

In apparatus as defined in claim 1; said hammer piston shifting in said first and second cylinders to alternately control flow of the fluid medium into said first and second cylinders and said lower portion of said housing structure; and means for alternately exhausting the fluid medium from said first and second cylinders and said lower portion of said housing structure.

Claim 7

In apparatus as defined in claim 1; said hammer piston shifting in said first and second cylinders to alternatively control flow of the fluid medium into said first and second cylinders and said lower portion of said housing structure; said housing structure having discharge ports communicating with the interior of said second cylinder through which fluid medium exhausts after downward movement of said hammer piston along said first and second cylinders; and means for exhausting the fluid medium from said lower portion of said housing structure after upward movement of said hammer piston in said housing structure.

Claim 8

In apparatus as defined in claim 1; said hammer piston shifting in said first and second cylinders to alternately control flow of the fluid medium into said lower portion of said housing structure and said first and second cylinders; said second cylinder having discharge ports controlled by said lower piston portion through which fluid medium in said first cylinder above said upper piston portion and fluid medium in said second cylinder exhaust after downward movement of said hammer piston along said first and second cylinders; and means for exhausting the fluid medium from said lower portion of said housing structure after upward movement of said hammer piston in said housing structure.

Claim 9

In percussion drilling apparatus: a housing structure connectible to a drill string; an anvil in the lower portion of said housing structure and connectible to a drill bit; said housing structure including an upper cylinder, a lower cylinder, and an intermediate cylinder therebetween of greater internal diameter than the diameters of said upper and lower cylinders; a hammer piston reciprocable in all of said cylinders for intermittently impacting against said anvil, said piston having upper and lower portions slidably reciprocable in said upper and lower cylinders, respectively, in sealed relation thereto to and an intermediate portion of greater diameter than said upper and lower piston portions slidably reciprocable in said intermediate cylinder in sealed relation thereto; said upper piston portion having an effective cross-sectional area substantially equal to the internal cross-sectional area of said upper cylinder; means for directing a fluid medium under pressure into said upper cylinder above said upper piston portion for action upon the full effective cross-sectional area of said upper piston portion and into said intermediate cylinder above said intermediate piston portion for driving said hammer piston downwardly toward said anvil, and means for directing the fluid medium under pressure into a lower portion of said housing structure for action upon said hammer piston to elevate said hammer piston in said housing structure.

Claim 10

In percussion drilling apparatus: a housing structure connectible to a drill string; an anvil in the lower portion of said housing structure and connectible to a drill bit; said housing structure including an upper cylinder, a lower cylinder, and an intermediate cylinder therebetween of greater internal diameter than the diameters of said upper and lower cylinders; a hammer piston reciprocable in all of said cylinders for intermittently impacting against said anvil, said piston having upper and lower portions slidably reciprocable in said upper and lower cylinders, respectively, in sealed relation thereto to and an intermediate portion of greater diameter than said upper and lower piston portions slidably reciprocable in said intermediate cylinder in sealed relation thereto; said upper piston portion having an effective cross-sectional area substantially equal to the internal cross-sectional area of said upper cylinder; means for directing a fluid medium under pressure into said upper cylinder above said upper piston portion for action upon the full effective cross-sectional area of said upper piston portion and into said intermediate cylinder above said intermediate piston portion for driving said hammer piston downwardly toward said anvil, and means for directing the fluid medium under pressure into a lower portion of said housing structure for action upon said hammer piston to elevate said hammer piston in said housing structure.

Claim 11

In apparatus as defined in claim 8; said last-mentioned means directing the fluid medium under pressure into said lower cylinder below said lower piston portion.

Claim 12

In apparatus as defined in claim 8; said last-mentioned means directing the fluid medium under pressure into said lower cylinder below said lower piston portion and into said intermediate cylinder below said intermediate piston portion.

Claim 13

In apparatus as defined in claim 8; said intermediate cylinder having discharge ports controlled by said intermediate piston portion through which fluid medium in said upper cylinder above said upper portion and fluid medium in said intermediate cylinder Exhaust after downward movement of said hammer piston along said upper, intermediate and lower cylinders.

Claim 14

In apparatus as defined in claim 8; said hammer piston shifting in said cylinders to alternately control flow of the fluid medium into said upper and intermediate cylinders and said lower portion of said housing structure.

Claim 15

In apparatus as defined in claim 8; said last-mentioned means directing the fluid medium under pressure into said lower cylinder below said lower piston portion; said hammer piston shifting in said cylinders to alternately control flow of the fluid medium into said upper and intermediate cylinders and lower cylinder.

Claim 16

In apparatus as defined in claim 8; said last-mentioned means directing the fluid medium under pressure into said lower cylinder below said lower piston portion; said hammer piston shifting in said cylinders to alternately control flow of the fluid medium into said upper and intermediate cylinders and lower cylinder; said intermediate cylinder having discharge ports controlled by said intermediate piston portion through which fluid medium in said upper cylinder above said upper piston portion and fluid medium in said intermediate cylinder exhaust after downward movement of said hammer piston along said upper, intermediate and lower cylinders; and means controlled by said lower piston portion for exhausting the fluid medium from said lower cylinder after upward movement of said hammer piston in said upper, intermediate and lower cylinders.

Claim 17

In percussion drilling apparatus: an outer housing structure connectible to a drill string; an upper cylinder in said housing structure and forming therewith an upper high fluid pressure passage; a lower cylinder in said housing structure spaced longitudinally below said upper cylinder and forming with said structure a lower fluid pressure passage; said housing structure providing an intermediate cylinder between said upper and lower cylinders of a substantially greater internal diameter than the internal diameters of said upper and lower cylinders; an anvil extending into the lower portion of said lower cylinder to close the same; a hammer piston reciprocable in all of said cylinders for intermittently impacting against said anvil; said upper cylinder having an inlet port through which fluid may flow from said upper passage into said upper cylinder; said lower cylinder having an exhaust port through which fluid may flow from said lower cylinder to said lower passage; said piston including upper and lower small diameter piston portions reciprocable in said upper and lower cylinders, respectively, and an intermediate large diameter piston portion reciprocable in said intermediate cylinder; said intermediate cylinder having discharge ports communicating the interior of said intermediate cylinder with the exterior of the housing structure; said piston having an impact passage communicating with said upper cylinder above said upper piston and intermediate cylinder and its discharge ports when said piston is in a lower position in said cylinders, said impact passage communicating with said upper cylinder above said upper piston and with said upper passage when said piston is in an upper position in said cylinders, at which time said intermediate portion closes said discharge ports; said piston having a return passage communicating with said lower cylinder below said lower piston portion and with said upper passage when said piston is in a lower position in said cylinder; said lower piston portion closing said lower passage when said piston is in a lower position in said cylinders and opening said lower passage to the interior of said lower cylinder when said piston is in an upper position in said cylinders.

Claim 18

In percussion drilling apparatus: an outer housing structure connectible to a drill string; an upper cylinder in said housing structure and forming therewith an upper high fluid pressure passage; a lower cylinder in said housing structure spaced longitudinally below said upper cylinder and forming with said structure a lower fluid pressure passage; said housing structure providing an intermediate cylinder between said upper and lower cylinders of a substantially greater internal diameter than the internal diameters of said upper and lower cylinders; an anvil extending into the lower portion of said lower cylinder to close the same; a hammer piston reciprocable in all of said cylinders for intermittently impacting against said anvil; said upper cylinder having an inlet port through which fluid may flow from said upper passage into said upper cylinder; said lower cylinder having an exhaust port through which fluid may flow from said lower cylinder to said lower passage; said piston including upper and lower small diameter piston portions reciprocable in said upper and lower cylinders, respectively, and an intermediate large diameter piston portion reciprocable in said intermediate cylinder; said intermediate cylinder having discharge ports communicating the interior of said intermediate cylinder with the exterior of the housing structure; said piston having an impact passage communicating with said upper cylinder above said upper piston and intermediate cylinder and its discharge ports when said piston is in a lower position in said cylinders, said impact passage communicating with said upper cylinder above said upper piston and with said upper passage when said piston is in an upper position in said cylinders, at which time said intermediate portion closes said discharge ports; said piston having a return passage communicating with said lower cylinder below said lower piston portion and with said upper passage when said piston is in a lower position in said cylinder; said lower piston portion closing said lower passage when said piston is in a lower position in said cylinders and opening said lower passage to the interior of said lower cylinder when said piston is in an upper position in said cylinders.

Claim 19

In apparatus as defined in claim 15; said lower piston portion having a side port establishing fluid communication between said return passage and intermediate cylinder below said large piston portion.

Claim 20

In apparatus as defined in claim 15; and passage means in said aNvil communicating with said lower passage to conduct fluid medium to the drill bit.