Nozzle assembly for horizontal drilling operations

Abstract

An improved water nozzle (100, 200) for use in a horizontal drill string (14) to prevent clogging of the string when water flow is stopped so a new section of drill rod (12) can be added to the string. The nozzle includes a tapered passage (116, 216) in which a ball (20) is installed. The resulting ball valve allows water injected into the one end of the rod string to flow through the nozzle during drilling. However, when water flow stops for attachment of a new section of rod to the string, the valve blocks the flow path back through the nozzle so sand, gravel, and other particles are not sucked into the string causing it to clog and necessitating that the string be withdrawn from the hole and disassembled so the nozzle can be cleaned out and unclogged.

Description

BACKGROUND OF THE INVENTION

This invention relates drills used for horizontal drilling; and more particularly, to an improved nozzle assembly incorporating a ball check valve to prevent the suction of sand into a drill head when a new section of drill rod is added to a drill string.

Horizontal drilling is a commonplace procedure used to route drainage lines under streets and roadways without having to tear up the surface of the road, to route various types of cable (e.g., fiberoptic cable) underground, beneath the road. The drilling operation involves successively connecting together lengths of hollow rods which are commonly referred to as a “string”. At the outer end of this string is a drilling tool which cuts through the soil and allows the string to be pushed forward through the soil, forming a tunnel through which the cable is ultimately routed. A spray nozzle or spray head is also connected at the outer end of the string, the cutting tool and spray nozzle together forming a drill head.

In a drilling operation, the string of rods is continuously rotated and pushed forward through the ground. The rotary action allows the drilling tool to cut into the soil, loosening it, and allowing the drill string to be pushed forward. It will be appreciated that the friction between the drilling tool and the soil causes the drilling tool to become heated; particularly so, if the soil is compacted or rocky. During this drilling operation, water is fed through the string of rods to the spray nozzle. The nozzle includes a restriction which causes the water to leave the nozzle as a high pressure spray which is directed at the drilling tool to cool the tool so that it cuts through the soil more easily, and does not bind or break.

Each section of rod forming the string is of a standard length (10 feet), and the drilling operation involves pushing on the outer end of the last rod in the string to force the entire string through the soil as the drilling tool cuts into it. The water is injected into the outer end of the last (outermost) section of rod and forced, under pressure, through the entire length of the string until it reaches the spray head. When a new section of rod is added to the string, the injection of water into the string is stopped until the leading end of the next section of rod is coupled to the trailing end of the last section of rod in the string.

A problem arises when drilling is being done through sand or a sandy soil, or soil containing gravel. This is because when water flow is cut off through the string of rod, preparatory to attaching the next section of rod to the string, a suction is created at the water nozzle which draws sand and/or gravel into the nozzle causing it to clog. The result is that the entire string of rod must be withdrawn for the tunnel, all of the rod sections having to be disconnected from one another to do this, cleaning out the nozzle to unclog it, and then reassembling the string so the that the tunnel can be completed. This is a time consuming and expensive delay which needs to be avoided.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to an improved water nozzle for use in the drill head of a horizontal drill string to prevent clogging when water flow is stopped so a new section of drill rod can be added to the string. The improved nozzle includes a one-way valve such as a ball valve or the like installed on the water flow path through the nozzle. The valve allows water injected into the one end of the rod string to flow through the nozzle when drilling through soil. However, when water flow stops for attachment of a new section of rod through the string, the valve blocks the flow path back through the nozzle into the string so sand, gravel, and other particles are not sucked into the string causing it to clog and necessitating that the string be withdrawn from the hole being drilled, and disassembled so that the nozzle or string can be cleaned out and unclogged.

Other objects and features will be in part apparent, and in part pointed out hereafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The objects of the invention are achieved as set forth in the illustrative embodiments shown in the drawings which form a part of the specification.

FIG. 1 is a simplified representation of a drilling process in which the improved nozzle of the present invention is used; and,

FIGS. 2A is an elevation view of a first embodiment of the improved nozzle of the present invention, and FIG. 2B is a similar view of a second embodiment of the nozzle;

FIGS. 3A and 3B are respective sectional views of the nozzles respectively taken along lines 3A-3A and 3B-3B;

FIGS. 4A and 4B are respective bottom plan views of the nozzles;

FIG. 5A is an elevation of one embodiment of the nozzle with a spray unit attached to the water outlet thereof, and FIG. 5B is a sectional view of the nozzle with the spray unit attached; and,

FIG. 6 illustrates the spray unit attached to the second embodiment of the spray nozzle.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION OF INVENTION

The following detailed description illustrates the invention by way of example and not by way of limitation. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what I presently believe is the best mode of carrying out the invention. As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

As shown in FIG. 1, a drilling rig 10 is for drilling a hole or tunnel T under a roadway R or other obstacle. The drilling operation includes connecting together successive lengths of a drill rods 12 to form a drill string indicated generally 14. At the forward end of the string is a cutting tool 16 for cutting through the soil, together with a water spray nozzle 18 which sprays water, under pressure, out of the forward end of the drill string. Although not shown in the drawings, water is pumped from a source through conduits in each drill rod 12 to nozzle 18. The nozzle has an outlet by which a stream of water is ejected from the nozzle into the soil surrounding the outer end of the drill string. The force of the water on the soil helps break up or loosen the soil, so as the drill string rotates through the soil, it is easier for cutting tool 16 to cut into the soil and create a pathway for the drill string to be driven forward through the soil. The water also helps keep the temperature of the cutting tool down.

When a new section of drill rod is to be added to the string, pumping of water through the string is stopped. Next, the outer end of the last section of drill rod in the string is disconnected from the water source, so a new section of rod can be added end of Heretofore, if the pressure level built up within the string is not allowed to bleed off, the resultant suction would draw sand, gravel, or other particles into the nozzle, clogging it, and necessitating withdrawal of drill string 14 so the nozzle could be unclogged.

An improved spray nozzle of the present invention substantially eliminates this problem. Two embodiments of the nozzle are shown in the drawings. One nozzle is generally indicated 100, and the other nozzle is generally indicated 200. Those skilled in the art will understand that nozzle 100 is useful in one type of drilling assembly, and nozzle 200 with another type.

As shown in FIGS. 2A-4B, each nozzle 100 and 200 comprises a metal block generally rectangular in shape. The difference between the two is that the lower portion of the front face of block 202 is chamfered, as indicated at 202, creating a rearwardly sloping lower section of a front face 204 of the nozzle. Front face 104 of nozzle 100 is a vertical face and has no sloping section. Respective pairs of horizontal bores 106-108 and 206-208 extend parallel to each other from the respective front faces 104, 204 of the nozzles, through the length of nozzles, to respective rear faces 110, 210 thereof. These bores are counterbored as indicated at 112-114 and 212-214. The bores and counterbores are used for attaching the respective nozzles 100, 200 to the outer end of the outermost drill rod 12 in string 14 using threaded bolts (not shown).

Next, each nozzle includes a respective passage 116, 216 which slopes upwardly from the lower portion of the respective front faces 104, 204 of the nozzles to the rear faces 110, 210 thereof. The outer end of passage 216 is formed in section 202 of front face 204 of nozzle 200. Both passages 116, 216 are tapered passages which are reduced in diameter from their outer end to the inner end of the passages formed in respective rear faces 110, 210 of the nozzles. A ball bearing 20 is positioned in each passage 116, 216. The diameter of ball bearing 20 is slightly smaller than the diameter of the passages 116, 216, at their outer end, and slightly larger than the diameter of the passages at their inner end. Accordingly, when water is pumped through string 14 of the drill rods, the water pressure forces the ball bearing through the passage 116 or 216 and because the ball bearing is smaller in diameter than the outer end of each passage, the water can flow out through the nozzle.

Referring to FIGS. 5A, 5B and 6, a spray unit 300 attaches to outer face 104, 204 of nozzles 100, 200, as shown in the drawings, to direct flow of water from the nozzle. The spray unit is also a metal block whose width corresponds to the width of either nozzle 100, 200 and is attached to the nozzle by welding, for example. The spray unit includes a pair horizontal passages 302, 304 extending through the unit. The inner end of these passages open into the outer end of passages 116 or 216, when the spray unit is attached to a nozzle, for water pumped into nozzles 100 or 200 to be sprayed out. The passages 302, 304 are of a uniform diameter which smaller in diameter than the diameter of the outer end of passages 116, or 216 so water injected into passage 116 or 216 will flow out of the nozzle through both passages 302 and 304.

During a horizontal drilling operation, water is pumped through drill string 14 and into nozzle 100 or 200, whichever is attached to the outer end of the drill rod 12 at the outer end of the string. As the water pushes through the passage 116 or 216, it forces ball bearing 20 through the passage until it abuts against an inner face 306 of spray unit 300 as shown by the solid line bearing in FIG. 5B. Because the diameter of the ball bearing is smaller than the diameter of the outer end of the passage, water readily flows past the ball bearing, into and through the passages 302, 304 in spray unit 300, and out the spray unit.

Now, when a new section of drill rod is to be added to the string, the flow of water is stopped. The suction created by the resulting back pressure now forces bearing 20 back up the passage 116, 216. As this passage narrows, the ball bearing is sucked into a position, shown by the left hand bearing in FIG. 5B, where it effectively and completely blocks the passage. Any sand, gravel, dirt, or other matter, which would otherwise be drawn back into the string of drill rods, is now stopped by the blocking position of the bearing in the passage, and cannot cause harm to the drilling unit. When the new section of rod is attached, and the pumping of water is resumed, the water pressure forces the bearing back to the outer end of the passage and any sand, gravel, or dirt is readily flushed out of the nozzle assemble through the spray unit. The result is that the ball valve formed by bearing 20 and the tapered passage 116 or 216 prevents damage to the drill unit and reduces down time and repair costs.

Claims

1. An improved water nozzle for use in a drill string used in generally horizontal drilling operations to prevent clogging when water flow through the string is stopped so a new section of a drill rod can be added to the string, comprising:

a nozzle adapted for mounting to an outer end of the drill rod on an outer end of the string;

a tapered passage extending through the nozzle, the passage tapering in diameter from the outer end of the nozzle to the inner end thereof; and,

a ball installed in the passage and freely movable therein, the ball allowing water injected into the rod string to flow through the nozzle during drilling, but when water flow is stopped for attachment of a new section of rod to the string, pressure on the ball created when the flow is stopped drawing the ball into a position blocking the passage so sand, gravel, and other particles are not sucked through the nozzle into the drill string causing the string to clog and necessitating disassembly of the string so the nozzle can be cleaned out and unclogged.

2. The improved nozzle of claim 1 in which the passage is a sloping passage.

3. The improved nozzle of claim 1 further including a spray unit fitted onto the outer end of the nozzle to direct water injected through the nozzle at an area surrounding the outer end of the string so to facilitate drilling.

4. The improved nozzle of claim 3 in which the spray unit includes at least one passage therethrough for water injected into the nozzle passage to be sprayed out of the spray unit.

5. The improved nozzle of claim 4 in which the spray unit includes a pair of passages.