Sealed rotary blast hole drill bit utilizing air pressure for seal protection

Claim 1

In a sealed rotary drill bit suitable for use with a rotating drill pipe for drilling shallow holes in the absence of liquid drilling mud, said drill bit having a body with a plurality of cutting elements, each of the cutting elements comprising a leg member having a projecting, conical cutter receiving journal, a conical cutter having an axially extending recess open at one end, and friction reducing bearings interior to the cutting element for rotatably mounting the conical cutter on the journal in spaced relationship with the journal, the improvement comprising: (a) each cutting element having at least one annular seal at the open end of the respective recess; (b) each cutting element having a circumferential porous gas restrictor concentric with and exterior to the respective at least one annular seal, the circumferential porous gas restrictor being spaced from the respective at least one annular seal to form an annular gas chamber therebetween; and (c) each leg member having a gas passageway extending into the respective annular gas chamber to carry pressurized gas into the respective annular gas chamber, each circumferential porous gas restrictor being formed of metal particles fused together such that the circumferential porous gas restrictor is strong enough to withstand the stresses of operation of the drill bit while providing a porosity which is capable of maintaining the pressure of the gas in the respective annular gas chamber while permitting some pressurized gas to be dissipated through its pores evenly around the circumference of the respective annular chamber.

Claim 18

A method of lubricating a plurality of circumferential seal gaps, each circumferential seal gap being located between a respective pair, in a plurality of pairs, of annular seals wherein the two annular seals in a pair are positioned in coaxial relationship with each other, and of utilizing air pressure to protect the outer annular seal of the two seals in a pair, the pairs of annular seals being in a drill bit having a body with a plurality of cutting elements, each such cutting element comprising a leg member having a projecting, conical cutter receiving journal, a conical cutter having an axially extending recess open at one end, friction reducing bearings interior to the cutting element for rotatably mounting the conical cutter on the journal in spaced relationship with the journal, and at least one lubricating fluid carrying conduit interior to the leg member and extending into the bearings, each pair of seals being an outer annular seal and an inner annular seal positioned at the open end of the axially extending recess of a respective conical cutter in coaxial relationship with each other to form a circumferential seal gap between the respective outer annular seal and the respective inner annular seal, each such outer annular seal having less resistance to the flow of lubricating fluid in the direction from the respective circumferential seal gap to the open end of the respective conical cutter than the resistance to the flow of lubricating fluid in the respective inner annular seal, each cutting element having at least one lubricating fluid carrying conduit interior to the respective cutting element to carry lubricating fluid into the respective circumferential seal gap, each cutting element having a circumferential porous gas restrictor concentric and exterior to the respective outer annular seal with the respective circumferential porous gas restrictor being spaced from the respective outer annular seal to form an annular gas chamber therebetween, and each leg member having a gas passageway extending into the respective annular gas chamber to carry pressurized gas into the respective annular gas chamber, the respective circumferential porous gas restrictor maintaining the pressure of the gas in the respective annular gas chamber, comprising the steps of: (a) providing for each cutting element a body of lubricating fluid at a respective first pressure; (b) when a body of lubricating fluid is at said first pressure, passing lubricating fluid from the respective body of lubricating fluid into the respective bearings by the respective at least one lubricating fluid carrying conduit extending into the bearings; (c) operating the drill bit for a period of time such that the temperature of the lubricating fluid in the respective bearings increases, thereby causing the lubricating fluid to expand and increase the pressure of the lubricating fluid to a second pressure which is higher than said first pressure; (d) whenever such lubricating fluid is at said second pressure, passing lubricating fluid from the respective bearings to the respective circumferential seal gap by the respective at least one lubricating carrying conduit extending into the respective circumferential seal gap; (e) passing pressurized gas through each gas passageway into each annular gas chamber; (f) maintaining the pressure of the pressurized gas in each annular gas chamber by the use of the respective circumferential porous gas restrictor; and (g) permitting lubricant which has exited past each respective outer annular seal and some pressurized gas in each respective annular gas chamber to be dissipated through the pores of the respective porous gas restrictor.

Claim 19

A method of lubricating a plurality of circumferential seal gaps, each circumferential seal gap being located between a respective pair, in a plurality of pairs, of annular seals wherein the two annular seals in a pair are positioned in coaxial relationship with each other, and of utilizing air pressure to protect the outer annular seal of the two seals in a pair, the pairs of annular seals being in a drill bit having a body with a plurality of cutting elements, each such cutting element comprising a leg member having a projecting, conical cutter receiving journal, a conical cutter having an axially extending recess open at one end, friction reducing bearings interior to the cutting element for rotatably mounting the conical cutter on the journal in spaced relationship with the journal, and at least one lubricating fluid carrying conduit interior to the leg member and extending into the bearings, each pair of seals being an outer annular seal and an inner annular seal positioned at the open end of the axially extending recess of a respective conical cutter in coaxial relationship with each other to form a circumferential seal gap between the respective outer annular seal and the respective inner annular seal, each such outer annular seal having less resistance to the flow of lubricating fluid in the direction from the respective circumferential seal gap to the open end of the respective conical cutter than the resistance to the flow of lubricating fluid in the respective inner annular seal, each cutting element having at least one lubricating fluid carrying conduit interior to the respective cutting element to carry lubricating fluid into the respective circumferential seal gap, each cutting element having a circumferential porous gas restrictor concentric and exterior to the respective outer annular seal with the respective circumferential porous gas restrictor being spaced from the respective outer annular seal to form an annular gas chamber therebetween, and each leg member having a gas passageway extending into the respective annular gas chamber to carry pressurized gas into the respective annular gas chamber, the respective circumferential porous gas restrictor maintaining the pressure of the gas in the respective annular gas chamber, comprising the steps of: (a) providing for each cutting element a body of lubricating fluid at a respective first pressure; (b) when a body of lubricating fluid is at said first pressure, passing lubricating fluid from the respective body of lubricating fluid into the respective bearings by the respective at least one lubricating fluid carrying conduit extending into the bearings; (c) operating the drill bit for a period of time such that the temperature of the lubricating fluid in the respective bearings increases, thereby causing the lubricating fluid to expand and increase the pressure of the lubricating fluid to a second pressure which is higher than said first pressure; (d) whenever such lubricating fluid is at said second pressure, passing lubricating fluid from the respective bearings to the respective circumferential seal gap by the respective at least one lubricating carrying conduit extending into the respective circumferential seal gap; (e) passing pressurized gas through each gas passageway into each annular gas chamber; (f) maintaining the pressure of the pressurized gas in each annular gas chamber by the use of the respective circumferential porous gas restrictor; and (g) permitting lubricant which has exited past each respective outer annular seal and some pressurized gas in each respective annular gas chamber to be dissipated through the pores of the respective porous gas restrictor.

Claim 20

A method of lubricating a plurality of circumferential seal gaps, each circumferential seal gap being located between a respective pair, in a plurality of pairs, of annular seals wherein the two annular seals in a pair are positioned in coaxial relationship with each other, and of utilizing air pressure to protect the outer annular seal of the two seals in a pair, the pairs of annular seals being in a drill being having a body with a plurality of cutting elements, each such cutting element comprising a leg member having a projecting, conical cutter receiving journal, a conical cutter having an axially extending recess open at one end, friction reducing bearings interior to the cutting element for rotatably mounting the conical cutter on the journal in spaced relationship with the journal, and a first lubricating fluid carrying conduit interior to the cutting element and extending into the bearings, each pair of seals being an outer annular seal and an inner annular seal positioned at the open end of the axially extending recess of a respective conical cutter in coaxial relationship with each other to form a circumferential seal gap between the respective outer annular seal and the respective inner annular seal, each such outer annular seal having less resistance to the flow of lubricating fluid in the direction from the respective circumferential seal gap to the open end of the respective conical cutter than the resistance to the flow of lubricating fluid in the respective inner annular seal, each cutting element having second and third lubricating fluid carrying conduits interior to the respective cutting element extending into the respective circumferential seal gap, each cutting element having a circumferential porous gas restrictor concentric and exterior to the respective outer annular seal with the respective circumferential porous gas restrictor being spaced from the respective outer annular seal to form an annular gas chamber therebetween, and each leg member having a gas passageway extending into the respective annular gas chamber to carry pressurized gas into the respective annular gas chamber, comprising the steps of: (a) providing for each cutting element a first body of bearing lubricating fluid at a respective first pressure; (b) when a first body of bearing lubricating fluid is at the respective first pressure, passing bearing lubricating fluid from the respective first body of bearing lubricating fluid into the respective bearings by the respective first lubricating fluid carrying conduit; (c) providing for each cutting element a second body of seal gap lubricating fluid contained entirely within the drill bit at a respective second pressure which is less than or equal to the respective first pressure; (d) passing seal gap lubricating fluid at the respective second pressure from the respective second body of seal gap lubricating fluid to the respective circumferential seal gap at a first rate by the respective second lubricating fluid carrying conduit; (e) operating the drill bit for a period of time such that the temperature of the respective second body of seal gap lubricating fluid, including the seal gap lubricating fluid in the respective second lubricating fluid carrying conduit, increases, thereby causing the seal gap lubricating fluid to expand and increase the pressure of the seal gap lubricating fluid to a respective third pressure which is greater than the respective first or said second pressures, thereby causing said seal gap lubricating fluid to pass into the respective circumferential seal gap at a second rate greater than said first rate; (f) operating the drill bit for a period of time such that the temperature of the bearing lubricating fluid in the respective bearings increases, thereby causing the respective bearing lubricating fluid to expand and increase the pressure on the bearing lubricating fluid in the respective bearings to a fourth pressure which is greater than or equal to said third pressure; (g) passing bearing lubricating fluid at the respective fourth pressure from the respective bearings into the respective circumferential seal gap by the respective third lubricating fluid carrying conduit thereby further pressuring the seal gap lubricating fluid in the respective circumferential seal gap; (h) passing pressurized gas through each gas passageway into each annular gas chamber; (i) maintaining the pressure of the pressurized gas in each annular gas chamber by the use of the respective circumferential porous gas restrictor; and (j) permitting lubricant which has exited past each respective outer annular seal and some pressurized gas in each respective annular gas chamber to be dissipated through the pores of the respective porous gas restrictor.

Claim 21

A method of lubricating a plurality of circumferential seal gaps, each circumferential seal gap being located between a respective pair, in a plurality of pairs, of annular seals wherein the two annular seals in a pair are positioned in coaxial relationship with each other, and of utilizing air pressure to protect the outer annular seal of the two seals in a pair, the pairs of annular seals being in a drill being having a body with a plurality of cutting elements, each such cutting element comprising a leg member having a projecting, conical cutter receiving journal, a conical cutter having an axially extending recess open at one end, friction reducing bearings interior to the cutting element for rotatably mounting the conical cutter on the journal in spaced relationship with the journal, and a first lubricating fluid carrying conduit interior to the cutting element and extending into the bearings, each pair of seals being an outer annular seal and an inner annular seal positioned at the open end of the axially extending recess of a respective conical cutter in coaxial relationship with each other to form a circumferential seal gap between the respective outer annular seal and the respective inner annular seal, each such outer annular seal having less resistance to the flow of lubricating fluid in the direction from the respective circumferential seal gap to the open end of the respective conical cutter than the resistance to the flow of lubricating fluid in the respective inner annular seal, each cutting element having second and third lubricating fluid carrying conduits interior to the respective cutting element extending into the respective circumferential seal gap, each cutting element having a circumferential porous gas restrictor concentric and exterior to the respective outer annular seal with the respective circumferential porous gas restrictor being spaced from the respective outer annular seal to form an annular gas chamber therebetween, and each leg member having a gas passageway extending into the respective annular gas chamber to carry pressurized gas into the respective annular gas chamber, comprising the steps of: (a) providing for each cutting element a first body of bearing lubricating fluid at a respective first pressure; (b) when a first body of bearing lubricating fluid is at the respective first pressure, passing bearing lubricating fluid from the respective first body of bearing lubricating fluid into the respective bearings by the respective first lubricating fluid carrying conduit; (c) providing for each cutting element a second body of seal gap lubricating fluid contained entirely within the drill bit at a respective second pressure which is less than or equal to the respective first pressure; (d) passing seal gap lubricating fluid at the respective second pressure from the respective second body of seal gap lubricating fluid to the respective circumferential seal gap at a first rate by the respective second lubricating fluid carrying conduit; (e) operating the drill bit for a period of time such that the temperature of the respective second body of seal gap lubricating fluid, including the seal gap lubricating fluid in the respective second lubricating fluid carrying conduit, increases, thereby causing the seal gap lubricating fluid to expand and increase the pressure of the seal gap lubricating fluid to a respective third pressure which is greater than the respective first or said second pressures, thereby causing said seal gap lubricating fluid to pass into the respective circumferential seal gap at a second rate greater than said first rate; (f) operating the drill bit for a period of time such that the temperature of the bearing lubricating fluid in the respective bearings increases, thereby causing the respective bearing lubricating fluid to expand and increase the pressure on the bearing lubricating fluid in the respective bearings to a fourth pressure which is greater than or equal to said third pressure; (g) passing bearing lubricating fluid at the respective fourth pressure from the respective bearings into the respective circumferential seal gap by the respective third lubricating fluid carrying conduit thereby further pressuring the seal gap lubricating fluid in the respective circumferential seal gap; (h) passing pressurized gas through each gas passageway into each annular gas chamber; (i) maintaining the pressure of the pressurized gas in each annular gas chamber by the use of the respective circumferential porous gas restrictor; and (j) permitting lubricant which has exited past each respective outer annular seal and some pressurized gas in each respective annular gas chamber to be dissipated through the pores of the respective porous gas restrictor.