Down-the-hole drill hammer having a coaxial accumulator

Abstract

A down-the-hole drill hammer comprising a housing, a backhead connected to the housing, an accumulator housed within the housing and downstream the backhead, and a piston reciprocally mounted within the housing. The accumulator includes an accumulator housing, a liner within the accumulator housing, and a flexible diaphragm circumscribing the liner and within the accumulator housing.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims the benefit under 35 U.S.C. § 119 (e) to U.S. Provisional Application No. 63 / 587,525, filed Oct. 3, 2023, and entitled “Down-The-Hole Drill Hammer Having an Accumulator,” the disclosure of which is hereby incorporated by reference in its entirety for all purposes.FIELD OF THE INVENTION

[0002] The subject disclosure relates generally to a down-the-hole (“DTH”) drill hammer for drilling earth, including rock. In particular, the present disclosure relates to a DTH drill hammer having an accumulator.BACKGROUND OF THE DISCLOSURE

[0003] During operation of a DTH drill hammer, a working fluid is pumped through a drill string connection into a supply inlet of the DTH drill hammer to allow the working fluid to flow through a control valve assembly and the various drive and return chambers of the hammer. Within the DTH drill hammer a percussive piston moves between a first position in contact with a shank of the drill bit and a second position out of contact with the drill bit shank. To maximize efficiency of the piston during movement, a pressure rise in the working fluid is desirable. Conventional DTH drill hammers use a control valve assembly to pull more working fluid from the attached surface pump. However, as the pump may be a considerable distance (e.g., 50 feet or more) from the control valve assembly, the pump has a delayed response, which can detrimentally affect piston movement efficiency.

[0004] Additionally, liquid hammering, sometimes called water-hammering, is a phenomenon common to DTH drill hammers that results from sudden increases in working fluid pressures. Water hammering is damaging to equipment such as control valves and piping joints due to intense and short-lived pressure pulses.

[0005] A need exists therefore for an improved DTH drill hammer which maximizes piston movement efficiency and reduces the detrimental effects of water hammering during operation.BRIEF SUMMARY OF THE DISCLOSURE

[0006] In accordance with an exemplary embodiment of the subject disclosure there is provided a DTH drill hammer comprising a housing, and an accumulator housed within the housing. The accumulator includes a liner, and a diaphragm circumscribing the liner. According to an aspect, the accumulator is completely housed within the housing. According to another aspect, the accumulator is completely housed within a proximal end of the housing. According to another aspect, the accumulator further comprises an accumulator housing for housing the liner and diaphragm.

[0007] According to an aspect, the diaphragm is a flexible diaphragm. According to another aspect, the diaphragm hermetically seals the liner. According to another aspect, the diaphragm is cylindrical. According to another aspect, the diaphragm includes annular protrusions operable to seal against the liner. According to another aspect, the liner includes a plurality of radially directed apertures.

[0008] According to an aspect, the DTH drill hammer further comprises supply ports housed within the housing and wherein the accumulator is adjacent the supply ports. According to an aspect, the DTH drill hammer further comprises a piston housed within the housing and wherein the accumulator is upstream the piston. According to an aspect, the DTH drill hammer further comprises a backhead connected to the housing and wherein the accumulator is downstream the backhead. According to an aspect, the DTH drill hammer further comprises a charge valve housed within the housing for supplying a compressible fluid to the accumulator.

[0009] In accordance with another exemplary embodiment of the subject disclosure there is provided a DTH drill hammer comprising a housing, a backhead connected to the housing, an accumulator housed within the housing and downstream the backhead, and a piston reciprocally mounted within the housing. The accumulator includes an accumulator housing, a liner within the accumulator housing, and a flexible diaphragm circumscribing the liner and within the accumulator housing.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0010] The foregoing summary, as well as the following detailed description of the exemplary embodiments of the subject disclosure, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, there are shown in the drawings exemplary embodiments. It should be understood, however, that the subject application is not limited to the precise arrangements and instrumentalities shown.

[0011] FIG. 1 is an elevation view of a DTH drill hammer in accordance with an exemplary embodiment of the subject disclosure;

[0012] FIG. 2 is a longitudinal cross-sectional view of the DTH hammer of FIG. 1;

[0013] FIG. 3 is an enlarged longitudinal cross-sectional view of a portion of the DTH hammer of FIG. 1;

[0014] FIG. 4 is a further enlarged longitudinal cross-sectional view of a portion of the DTH hammer of FIG. 1;

[0015] FIG. 5 is a proximal perspective view of an accumulator housing of an accumulator of the DTH hammer of FIG. 1;

[0016] FIG. 6 is a longitudinal cross-sectional view of the accumulator housing of FIG. 5;

[0017] FIG. 7 is an elevation view of a diaphragm of the accumulator of the DTH hammer of FIG. 1;

[0018] FIG. 8 is a longitudinal cross-sectional view of the diaphragm of FIG. 7;

[0019] FIG. 9 is an elevation view of a liner of the accumulator of the DTH hammer of FIG. 1;

[0020] FIG. 10 is a longitudinal cross-sectional view of the liner of FIG. 9;

[0021] FIG. 11 is an elevation view of a charge valve of the accumulator of the DTH hammer of FIG. 1;

[0022] FIG. 12 is a proximal end view of the charge valve of FIG. 11;

[0023] FIG. 13 is a longitudinal cross-sectional view of the charge valve of FIG. 11;

[0024] FIG. 14 is a side view of a charge valve closure plug of the accumulator of the DTH hammer of FIG. 1; and

[0025] FIG. 15 is a proximal end view of the charge valve closure plug of FIG. 14.

[0026] Other features and advantages of the subject disclosure will be apparent from the following more detailed description of the exemplary embodiments.DETAILED DESCRIPTION

[0027] Reference will now be made in detail to the various exemplary embodiments of the subject disclosure illustrated in the accompanying drawings. Wherever possible, the same or like reference numbers will be used throughout the drawings to refer to the same or like features. It should be noted that the drawings are in simplified form and are not drawn to precise scale. Certain terminology is used in the following description for convenience only and is not limiting. Directional terms such as top, bottom, left, right, above, below and diagonal, are used with respect to the accompanying drawings. The term “distal” shall mean away from the center of a body. The term “proximal” shall mean closer towards the center of a body and / or away from the “distal” end. The words “inwardly” and “outwardly” refer to directions toward and away from, respectively, the geometric center of the identified element and designated parts thereof. Such directional terms used in conjunction with the following description of the drawings should not be construed to limit the scope of the subject disclosure in any manner not explicitly set forth. Additionally, the term “a,” as used in the specification, means “at least one.” The terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import.

[0028] “About” as used herein when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass variations of ±20%, ±10%, ±5%, ±1%, or ±0.1% from the specified value, as such variations are appropriate.

[0029] “Substantially” as used herein shall mean considerable in extent, largely but not wholly that which is specified, or an appropriate variation therefrom as is acceptable within the field of art. “Exemplary” as used herein shall mean serving as an example.

[0030] Throughout this disclosure, various aspects of the subject disclosure can be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the subject disclosure. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 2.7, 3, 4, 5, 5.3, and 6. This applies regardless of the breadth of the range.

[0031] Furthermore, the described features, advantages and characteristics of the exemplary embodiments of the subject disclosure may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize, in light of the description herein, that the present disclosure can be practiced without one or more of the specific features or advantages of a particular exemplary embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all exemplary embodiments of the subject disclosure.

[0032] Referring now to an exemplary embodiment shown in the figures, the subject disclosure provides a DTH drill hammer 10. As shown in FIG. 1, the DTH drill hammer 10 comprises a backhead 12, a housing 14 threadedly connectable to the backhead, a chuck 16 threadedly connectable to the housing, and a drill bit 18. Referring to FIG. 2, the DTH drill hammer 10 further comprises a check valve or poppet valve 20, an accumulator 22, a porting assembly 24 and a piston 26.

[0033] The backhead is configured as generally shown inFIGS. 2 and 3. The backhead 12 is connected to the housing 14 and includes a supply inlet 28 that receives working fluid from a drill string (not shown) attachable to the backhead 12. Working fluid passes through the supply inlet 28 into the internals of the DTH drill hammer 10. However, before passing to the internals of the DTH hammer, the flow of working fluid first encounters the poppet valve 20, as further described below. In some examples, the backhead 12 is threaded at its proximal end for coupling to the drill string; however, various other coupling mechanisms are contemplated to be within the scope of the subject disclosure. In some examples, the backhead includes one or more planar surfaces 30 configured to be engaged by an unillustrated wrench or similar tool used for connecting and disconnecting the backhead to and from the drill string.

[0034] The drill bit 18 is disposed at the distal end of the DTH drill hammer 10 and is generally configured as shown in FIG. 2. According to the subject disclosure, the drill bit 18 can be a single integral piece configured with a head 32 and a shank 34. The head 32 is generally configured similarly to conventional heads used in DTH drill hammers and includes a plurality of inserts (also known as cutting inserts). In some examples, the cutting inserts are comprised of diamond or other high strength cutting material and are designed to cut into earth. The shank 34 is on the proximal end of the drill bit 18 and includes an impact surface 36 configured to be engaged by the piston 26. In some examples, the drill bit 18 also defines one or more bores 38 which allow for working fluid to flow therethrough.

[0035] The housing 14 is configured as shown in FIGS. 1 and 2 and comprises a generally cylindrical hollow body that at least partially houses the backhead 12 and the drill bit 14, as well as additional components described below. The housing fully and completely houses the accumulator 22, the porting assembly 24 and the piston 26, with the accumulator completely housed within a proximal end of the housing upstream the piston.

[0036] The poppet valve 20 is generally configured as best shown in FIG. 3. The poppet valve 20 is mounted within the housing 14 adjacent the backhead 12 and controls the flow of working fluid through the backhead. The check valve 20 includes a poppet valve housing 40 with a chamfered proximal end 42 and an open distal end. The poppet valve housing 40 further defines at least one lateral opening 44 in fluid communication with a passageway 46 extending therethrough for allowing passage of working fluid to the internals of the DTH drill hammer 10. The chamfered end 42 may include an annular groove for receiving a seal, such as an elastomeric O-ring seal 48. The poppet valve 20 is configured to receive a biasing member 50 which may be positioned internally of the poppet valve housing 40 for biasing the poppet valve towards a closed position against the backhead 12. The biasing member 50 can be any biasing member suitable for the intended purposes described above, such as a compression spring, leaf spring, an elastomer, and the like.

[0037] In operation, the poppet valve 20 is movable between a first closed position and a second open position. In the first position, the chamfered end 42 sealingly engages a correspondingly chamfered internal wall of the backhead 12 to seal off the flow of working fluid from entering the internals of the DTH drill hammer 10 from the supply inlet 28. In the second position, the poppet valve 20 is spaced from the backhead 12 thereby allowing a flow of working fluid from the backhead 12 to flow through the accumulator 18 and other internal components of the DTH drill hammer. The poppet valve 20 is moved from the first position to the second position when a supply pressure of working fluid exceeds the biasing force of the biasing member 50 which biases the chamfered end 42 of the poppet valve into contact with the chamfered internal wall of the backhead 12.

[0038] As best shown in FIGS. 3 and 4, the accumulator 22 is housed within the housing 14 downstream the backhead 12. According to an exemplary embodiment, the accumulator 22 includes a diaphragm 52, a liner 54, an accumulator housing 56, and a charge valve 58. The diaphragm 52 circumscribes the liner 54 and the accumulator housing 56 circumscribes the diaphragm. In other words, the accumulator housing houses the liner and the diaphragm. The diaphragm 52 is generally configured as shown in FIGS. 7 and 8. The diaphragm includes a generally cylindrical body comprised of a flexible material that creates a barrier between the incompressible working fluid and a compressible fluid contained in an annular volume 60 (FIGS. 3 and 4) provided within the accumulator housing 56. The exterior of the diaphragm 52 includes a plurality of annular protrusions 62 disposed on its distal and proximal ends to establish a hermetic seal between the diaphragm and the accumulator housing 56. An inner surface of the diaphragm 40 also includes one or more interior annular protrusions 64 (FIG. 8) configured to be engaged with corresponding annular grooves 66 (FIGS. 9 and 10) provided the liner 54 to establish a hermetic seal between the diaphragm and the liner.

[0039] The liner 54 is generally configured as shown in FIGS. 9 and 10. The liner 54 includes a generally cylindrical body and includes a plurality of small, radially-directed apertures 68 therein to allow working fluid to flow in and out of the inner diameter of the liner 54 and within the interior of the diaphragm 52. The apertures 68 are sized such that they are large enough to allow passage of working fluid but small enough to prevent extrusion and cutting of the diaphragm 52 when only gas pressure is present. In some examples, the apertures 68 are arranged evenly in rows and columns about the liner 54. However, it is also contemplated that the apertures 68 could be disposed in other arrangements, as desired.

[0040] The accumulator housing 56 is configured as shown in FIGS. 5 and 6 and includes a generally cylindrical body. The accumulator housing 56 is the outermost portion of the accumulator 22 and houses the liner 54 and diaphragm 52. The accumulator housing 56 is housed within the housing 14 and is disposed adjacent the backhead 12. In other words, the accumulator 22 is completely housed within the housing 14. The accumulator housing 56 includes a threaded bore 70 for receiving the charge valve 58 therein as described below. As best shown in FIG. 4, the threaded bore 70 includes an unthreaded distal portion 71 which is in fluid communication with the annular volume 60 provided within the accumulator housing 56 and defined as a space or volume between the accumulator housing and the diaphragm. The annular volume 60 surrounds or circumscribes the diaphragm.

[0041] The charge valve 58 is generally configured as shown in FIGS. 11-13. The charge valve is housed within the housing 14 and the accumulator housing 56 and comprises a charge valve body 72 including a proximal threaded portion that threadedly engages with the threaded bore 70 of the accumulator housing. The charge valve 58 further includes an unthreaded portion distal to the threaded portion and a pointed distal tip 74. In an exemplary embodiment, the pointed distal tip 74 has an approximately 60-degree chamfering for sealing against a correspondingly chamfered recess distal to the threaded bore 70 of the accumulator housing 56; however, various other sealing configurations are contemplated to be within the scope of the subject disclosure. The charge valve 58 also includes an axially extending bore 76 that is in fluid communication with a radially extending through hole 78 disposed adjacent the pointed distal tip 74. The through hole 78 permits pressurized compressible fluid to enter the annular volume 60 when the pointed distal tip is separated from the accumulator housing 56 such as when filling the annular volume. In other words, the charge valve 58 supplies a compressible fluid, e.g., a gas, to the annular volume 60 defined as a space or volume between the accumulator housing 56 and the diaphragm 52. A proximal end of the charge valve 58 desirably includes a polygonal, e.g., hexagonal, socket 80 for receiving an unillustrated tool such as a wrench or the like for threading and unthreading the charge valve 58 into and out of the threaded bore 70 of the accumulator housing 56.

[0042] FIGS. 14 and 15 best show the general construction of an exemplary embodiment of a charge valve closure plug 82 for selectively permitting access to and sealingly enclosing the charge valve 58 in the treaded bore 70 of the accumulator housing 56. The charge valve closure plug 82 includes a threaded body 84 having threads configured to threadedly engage the threaded bore 70. At its proximal end the charge valve closure plug 82 includes a radially enlarged head 86 provided with a polygonal, e.g., hexagonal, socket 88 for receiving an unillustrated tool such as a wrench or the like for threading and unthreading the charge valve closure plug 82 into and out of the threaded bore 70. Immediately beneath the radially enlarged head 86 the charge valve closure plug 82 desirably includes an annular seal member 90 such as an O-ring or the like. The annular seal member 90 operates to create a fluid-tight seal with the threaded bore 70 when the plug is fully threaded thereinto in order to prevent leakage of compressible fluid from the annular volume 60 during operation of the DTH drill hammer 10.

[0043] As noted above, the annular volume 60 may be filled with a compressible fluid such as a gas. When pressure from the working fluid is applied to the inner surface of the diaphragm 52, the diaphragm flexes outwardly until pressure is equal outside and inside the diaphragm. For example, the compressible fluid may be pressurized to a pressure of roughly 50% of the anticipated pressure of the working fluid such that during normal operation the accumulator 22 is configured to store additional working fluid between the liner 54 and the diaphragm 52. Thus, when liquid pressure is applied by the working fluid, the gas volume in the annular volume 60 is reduced by roughly 50% to equalize the working fluid liquid pressure on the inner side of the diaphragm with the gas pressure in the annular volume. In other words, the pressurized liquid working fluid expands the flexible diaphragm which, in turn, compresses the gas in the annular volume 60.

[0044] In operation, when a sudden demand for working fluid is created by operation of the DTH drill hammer, liquid pressure in the accumulator 22 drops. Responsive to the reduced liquid pressure, the compressed gas in the annular volume 60 expands and thereby constricts the flexible diaphragm and nearly instantly supplies additional working fluid from the accumulator 22 within inches of the demand versus a pump which could be 50 or more feet away.

[0045] The piston 26 is generally configured as shown in FIG. 2. The piston 22 is reciprocally housed within the housing 14 and includes a proximal end 92 in fluid communication with the accumulator 22 and the porting assembly 24. The piston further includes a distal end 94 configured to engage the impact surface 36 of the drill bit shank 34 during operation. The piston 26 is configured to reciprocatively and percussively move within the housing 14 between a first position and a second position in a well-known manner for impacting the drill bit 18. In the first position, the piston 26 is disposed away from the drill bit 18 and in the second position the piston is engaged with the drill bit to provide an impact force to the drill bit. The percussive movement of the piston 26 is powered by a power source that supplies the working fluid to the DTH drill hammer 10 via the drill string and which flows through the poppet valve 20, the accumulator 22, and the porting assembly 24 to drive percussive action.

[0046] The porting assembly 24 is generally configured as shown in FIG. 3. The porting assembly is disposed within the housing 14 adjacent to and downstream of the accumulator 22 and adjacent to and upstream the piston 26. The porting assembly 24 controls operation of the piston during use by porting working fluid to the piston and exhausting working fluid from the piston. When working fluid is ported to the piston, the piston moves distally and strikes the drill bit shank. Conversely, when working fluid is ported away from the piston, the piston moves proximally and away from the drill bit shank.

[0047] Referring again to FIG. 3, the DTH drill hammer 10 includes supply ports 100, drive ports 102 and exhaust ports 104. According to an exemplary embodiment, the accumulator 22 is adjacent the supply ports 100. The porting assembly 24 operates to selectively distribute working fluid to the drive ports 102 and exhaust ports 104 depending on the position of the piston 26 within the housing 14.

[0048] In operation, working fluid is pumped through the drill string connection into the supply inlet 28 which in turn opens the poppet valve 20 to allow the working fluid to flow through the accumulator 22, through the porting assembly 24, and into the various drive and exhaust chambers to drive percussive movement of the piston 26. During operation, the piston 26 moves percussively between the first position and the second position. To maximize efficiency of the piston 26 during movement, a pressure rise in the working fluid is desirable. Conventional DTH drill hammers use a control valve assembly to pull more working fluid from the attached ground surface pump. However, since the pump may be a far distance (e.g., 50 feet or more away) from the control valve assembly, the pump has a delayed response. The reason for this is a pressure wave must travel to and from the control valve assembly and the ground surface hydraulic pump supplying fluid to the system. The wave can only travel at the speed of sound in the liquid (4700 ft / s in water) and the pump can be 50 or more feet away. For example, at 50 feet the pressure wave will not respond to a demand for 21 ms—the round trip time to travel 50 feet. That delay represents more than 80% of the entire piston strike cycle when operating at 40 hz.

[0049] To overcome this operational deficiency, the DTH drill hammer 10 as described herein uses the accumulator 22 to quickly provide additional fluid volume to the porting assembly 24, as the accumulator is disposed adjacent thereto, thereby eliminating the working fluid delay essentially entirely. As noted above, the accumulator 22 uses the diaphragm 52 which seals compressible fluid, e.g., gas, in the annular volume 60 from the working fluid. Therefore, when a sudden demand for working fluid is created by the piston 26, the compressible fluid in the annular volume 60 expands, thereby constricting the diaphragm 52 and pushing additional working fluid to the porting assembly 24. In other words, the accumulator 22 nearly instantly supplies additional working fluid to the adjacent control valve assembly 24.

[0050] Additionally, the elastic nature of the diaphragm within the accumulator 22 substantially reduces liquid hammering caused by the cyclical opening and closing of the porting assembly 24. Liquid hammering, sometimes called water-hammering, is damaging to equipment and piping joints due to its intense and short-lived pressure pulses. As such, the DTH drill hammer 10 as described herein has increased control valve life in addition to improved performance.

[0051] It will be appreciated by those skilled in the art that changes could be made to the various aspects described above without departing from the broad inventive concept thereof. It is to be understood, therefore, that the subject application is not limited to the particular aspects disclosed, but it is intended to cover modifications within the spirit and scope of the subject application as defined by the appended claims.

Claims

1. A down-the-hole drill hammer comprising:a housing; andan accumulator housed within the housing, the accumulator including:a liner, anda diaphragm circumscribing the liner.

2. The down-the-hole drill hammer of claim 1, wherein the diaphragm is a flexible diaphragm.

3. The down-the-hole drill hammer of claim 1, wherein the diaphragm hermetically seals the liner.

4. The down-the-hole drill hammer of claim 1, wherein the diaphragm is cylindrical.

5. The down-the-hole drill hammer of claim 1, wherein the diaphragm includes annular protrusions operable to seal against the liner.

6. The down-the-hole drill hammer of claim 1, wherein the accumulator further comprises an accumulator housing for housing the liner and diaphragm.

7. The down-the-hole drill hammer of claim 1, wherein the accumulator is completely housed within the housing.

8. The down-the-hole drill hammer of claim 1, wherein the accumulator is completely housed within a proximal end of the housing.

9. The down-the-hole drill hammer of claim 1, further comprising supply ports housed within the housing and wherein the accumulator is adjacent the supply ports.

10. The down-the-hole drill hammer of claim 1, further comprising a piston housed within the housing and wherein the accumulator is upstream the piston.

11. The down-the-hole drill hammer of claim 1, further comprising a backhead connected to the housing and wherein the accumulator is downstream the backhead.

12. The down-the-hole drill hammer of claim 1, wherein the liner includes a plurality of radially-directed apertures.

13. The down-the-hole drill hammer of claim 1, further comprising a charge valve housed within the housing for supplying a compressible fluid to the accumulator.

14. A down-the-hole drill hammer comprising:a housing;a backhead connected to the housing;an accumulator housed within the housing and downstream the backhead, the accumulator including:an accumulator housing,a liner within the accumulator housing, anda flexible diaphragm circumscribing the liner and within the accumulator housing; anda piston reciprocally mounted within the housing.

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