Down-the-hole hammer with adjustable air consumption

Abstract

A down-the-hole hammer (100) includes: a barrel (102) having a longitudinal axis (101) and defining an intermediate chamber (200, 204) and a bottom chamber (202); a piston (160) defining a top chamber (166) and slidable within the barrel (102) between the intermediate chamber (200, 204) and the bottom chamber (202); a control tube (140) having a distal port (149); and an air distributor (150) having a first distal port (156) and a second distal port (156 '). The control tube (140) is indexable between a plurality of rotational positions to regulate which of the first distal port (156) and the second distal port (156 ') of the air distributor (150) is aligned with the distal port (149) of the control tube (140).

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to a drill hammer, and more particularly, to a down-the-hole hammer having adjustable air consumption. BACKGROUND

[0002] Ground drilling is a necessary operation in many industries including mining, oil and gas extraction, construction, geothermal drilling, and the like. Various types of equipment can be used for ground drilling, including drill hammers to generate impact and percussive forces to break up the ground and advance a drill bit through rock and soil. One type of drill hammer, known as a down-the-hole hammer, is mounted to the bottom end of a drill string and includes (or is directly adjacent to) a drill bit. Down-the-hole hammers typically produce hammering action by pneumatic or hydraulic action, in which a motive fluid (e.g., air, water, or drilling mud) is supplied along the drill string to the hammer.

[0003] U.S. Patent No. 6,454,026 (“the ‘026 patent”), issued September 24, 2002, describes a down-the-hole percussion hammer that includes a cylindrical housing adapted to carry a drill bit, and a piston mounted in the housing for reciprocating movement to repeatedly strike the drill bit. A proximal subassembly is mounted at a proximal portion of the housing and includes a distal face extending toward the piston. A feed tube is mounted to the proximal subassembly and extends distally along a central axis of the housing and defines an air-conducting passageway. The piston includes an axial through-hole that slidably receives the feed tube. The distal face and the feed tube together define a recess that is open toward the piston. A removable volume transformer can be inserted into the recess to vary the volume of the space in which the piston slides, and thus control the pressure at which the piston operates. To access the volume transformer, much of the hammer must be disassembled, so setting the operating pressure of the hammer is both time-consuming and labor-intensive.

[0004] The down-the-hole hammer of the present disclosure can solve one or more of the problems described above and / or other problems in the art. However, the scope of the present disclosure is not limited by the ability to solve any particular problem. SUMMARY

[0005] In one aspect, the present disclosure relates to a down-the-hole hammer comprising a barrel having a longitudinal axis and defining a middle chamber and a bottom chamber, a piston defining a top chamber and slidable within the barrel between the middle chamber and the bottom chamber, a control tube having a distal port, and an air distributor having a first distal port and a second distal port. The control tube is indexable between a plurality of rotational positions to adjust which of the first and second distal ports of the air distributor is aligned with the distal port of the control tube.

[0006] In another aspect, this disclosure relates to a method for regulating air consumption in a down-the-hole hammer, the down-the-hole hammer including a control tube and an air distributor. The control tube includes a distal port, and the air distributor includes a first distal port and a second distal port. The first distal port of the air distributor corresponds to a first target airflow rate, and the second distal port of the air distributor corresponds to a second target airflow rate. The method includes rotating the control tube relative to the air distributor such that the distal port of the control tube is aligned with one of the first and second distal ports of the air distributor. Attached Figure Description

[0007] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments and, together with the description, serve to explain the principles of the disclosed embodiments.

[0008] Figure 1 This is a side view of a down-the-hole hammer according to various aspects of this disclosure.

[0009] Figure 2 yes Figure 1 A side view of a down-the-hole hammer, with its cylinder removed to show the internal components.

[0010] Figure 3 It is along Figure 1 Section line 3-3 shows the view of the first operating position. Figure 1 A cross-sectional side view of a down-the-hole hammer.

[0011] Figure 4 yes Figure 1 A partial side view of a down-the-hole hammer, with its cylinder removed to show the internal components.

[0012] Figure 5 It is along Figure 4 Observation of section line 5-5 Figure 1 A cross-sectional side view of a down-the-hole hammer.

[0013] Figure 6 yes Figure 1 A perspective view of a down-the-hole hammer check valve.

[0014] Figure 7 yes Figure 1 A perspective view of the proximal end of a down-the-hole hammer.

[0015] Figure 8 yes Figure 1 A perspective view of the check valve, control pipe, and air distributor of a down-the-hole hammer.

[0016] Figure 9 yes Figure 4 A perspective view of the air distributor and related components in detail 9.

[0017] Figure 10 is Figure 1 a perspective view of an air distributor and a retainer seat of a down-the-hole hammer.

[0018] Figure 11 is a cross-sectional front view of the retainer seat and associated components as viewed along section line 11-11 of Figure 9

[0019] Figure 12A is a cross-sectional side view of the down-the-hole hammer of Figure 1 as viewed along section line 3-3 in a second operating position. Figure 1

[0020] Figure 12B is a cross-sectional side view of the down-the-hole hammer of Figure 1 as viewed along section line 3-3 in a third operating position. Figure 1

[0021] Figure 12C is a cross-sectional side view of the down-the-hole hammer of Figure 1 as viewed along section line 3-3 in a fourth operating position. Figure 1

[0022] Figure 12D is a cross-sectional side view of the down-the-hole hammer of Figure 1 as viewed along section line 3-3 in a fourth operating position. Figure 1

[0023] Figure 12E is a cross-sectional side view of the down-the-hole hammer of Figure 1 as viewed along section line 3-3 in a fifth operating position. Figure 1

[0024] Figure 13 A flowchart depicting an exemplary method for regulating air consumption of a down-the-hole hammer according to aspects of the present disclosure is provided. DETAILED DESCRIPTION

[0025] ​​​​​​The foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the features claimed. As used herein, the terms "comprise", "comprising", "has", "having", "include", "including", or other variations thereof, are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. In this disclosure, unless otherwise stated, relative terms, such as, for example, "about", "substantially", and "approximately" are used to indicate a possible variation of ±10% of the stated value. Throughout the drawings, like reference numerals refer to like parts.

[0026] Referring now to Figures 1-3 , a downhole drilling hammer (hereinafter "hammer 100") in accordance with aspects of the present disclosure includes a barrel 102 that houses various other components of the hammer 100. The barrel 102 defines a longitudinal axis 101 that extends from a top (or proximal) end 104 to a bottom (or distal) end 106 of the barrel 102. The barrel 102 is generally cylindrical and includes an inner diameter that defines a bore 103 (see Figure 3 ) that extends from the proximal end 104 to the distal end 106. As will be described herein, the bore 103 of the barrel 102 includes an annular recess 108 (see Figure 3 ) that provides a flow path to selectively allow airflow between various regions of the barrel 102 during operation of the hammer 100.

[0027] The adapter 110 is connected to the proximal end 104 of the barrel 102, for example, by a threaded connection 113 (see Figure 3 ). The adapter 110 includes an interface 112 (e.g., a threaded fitting as shown) for connection to a drill string (not shown). (For the sake of clarity, the threaded connection of the adapter 110 is not shown in all of the figures.) The adapter 110 also includes a bore 114 that receives pressurized air supplied from the drill string (e.g., via a compressor).

[0028] A hammer drill bit (hereinafter “bit 120”) is disposed in the distal end 106 of the barrel 102 in a manner that allows limited sliding of the bit 120 along the longitudinal axis 101. In particular, a drive chuck 105 is threadably connected into the distal end 106 of the barrel 102. The drive chuck 105 includes an internal anti-rotation feature (e.g., splines) that interacts with a complementary feature on the bit 120 to allow the bit 120 to slide along the axis 101 but not rotate relative to the barrel 102. When threadably connected into the barrel 102, the drive chuck 105 holds a retaining ring 123 (which can be formed from two half-rings) within the barrel 102 adjacent to the guide sleeve 121. When the bit 120 is in the distal-most position, the retaining ring 123 limits the distal travel of the bit 120 by engaging a protrusion 125 (see Figure 3 ) of the bit 120, thereby preventing the bit 120 from sliding out of the barrel 102. (Note that the guide sleeve 121 and retaining ring 123 are only shown in Figure 3 to improve clarity of the other figures.) The bit 120 includes a distal end having one or more digging features 122 (e.g., tips, teeth, etc.) for cutting / breaking up ground and / or rock. The bit 120 is connected to or integrally formed with a foot valve 124. A bore 126 extends through the foot valve 124 and at least partially through the bit 120. One or more exhaust ports 128 extend from the bore 126 and open to an outer surface (e.g., distal end) of the bit 120. As will be described in greater detail herein, the bit 120 includes a strike face 129 that is struck by the piston 160 of the hammer 100 to cause the bit 120 to impact against a ground, rock face, etc.

[0029] A check valve 130 is disposed within the barrel 102 and / or the adapter 110 and is configured to open in response to air pressure supplied to the bore 114 of the adapter 110. The check valve 130 is configured to close when the pressure of the hammer 100 exceeds the pressure in the drill string (not shown). As such, the check valve 130 can occasionally close during operation of the hammer 100 depending on the relative air pressure between the hammer 100 and the drill string. The check valve 130 includes a plug 132 biased against the tapered section 116 of the adapter 110 of the hammer 100 by a spring 134. The spring 134 can be configured to compress when a predetermined air pressure acts on the plug 132, thereby allowing the plug 132 to slide distally within the bore 114 and allowing air to bypass the plug 132 toward the distal end 106 of the barrel 102.

[0030] Referring now to Figures 5-7 , the proximal end 135 of the plug 132 includes a tool interface 136 configured to receive a wrench or other tool to facilitate rotation of the plug 132. In the illustrated aspect, the tool interface 136 is a hex socket configured to receive a hex wrench, although other forms of tool interface 136 can be considered within the scope of the present disclosure. As Figure 7As shown in FIG. 1, the tool interface 136 is accessible via the adapter 110 without removing the adapter 110 from the barrel 102. To access the tool interface 136, it is only necessary to disconnect the drill string (not shown) from the adapter 110.

[0031] Referring now to Figures 4-9 , the distal end 137 of the plug 132 includes one or more rotational interlock surfaces 138 configured to engage a complementary rotational interlock surface 147 on a control tube 140 of the hammer 100. In some aspects, the one or more rotational interlock surfaces 138 include four substantially planar surfaces arranged in a square configuration about the longitudinal axis 101.

[0032] Referring now to Figures 2-5 and Figure 8 , the control tube 140 defining a hollow bore 142 extending coextensively with the longitudinal axis 101 is disposed within the barrel 102. The control tube 140 can extend at least partially into the bore 114 of the adapter 110. The spring 134 of the check valve 130 can be seated on a shoulder 143 (see Figure 5 ) of the bore 142 of the control tube 140. The control tube 140 includes a proximal end 145 extending into the bore 114 of the adapter 110, and a distal end 146 extending into a bore 151 of an air distributor 150 (see Figure 5 ). The bore 142 extends through the proximal end 145 and the distal end 146 of the control tube 140. As shown in Figure 3 and Figure 5 , the control tube 140 includes a plurality of proximal ports 144 arranged circumferentially about the control tube 140. The illustrated aspect includes six proximal ports 144, but in other aspects can include more or fewer proximal ports (including a single proximal port 144). The control tube 140 also includes a plurality of distal ports 149 extending radially through the distal end 146 into the bore 142. The illustrated aspect includes two distal ports 149, but in other aspects can include more or fewer distal ports (including a single distal port 149).

[0033] The proximal end 145 of the control tube 140 includes one or more rotational interlock surfaces 147 that are complementary to the rotational interlock surfaces 138 of the plug 132 of the check valve 130. In some aspects, the one or more rotational interlock surfaces 147 include four substantially flat surfaces arranged in a square configuration about the longitudinal axis 101. Thus, the rotational interlock surface(s) 147 of the control tube 140 engage the rotational interlock surface(s) 147 of the plug 132 to rotationally lock the plug 132 to the control tube 140. As such, torque applied to the plug 132 is transmitted to the control tube 140 via the connection between the rotational interlock surface(s) 147 and the rotational interlock surface(s) 138. The rotational interlock surface(s) 138 of the plug 132 and the rotational interlock surface(s) 147 of the control tube 140 are in a sliding fit engagement such that the plug 132 is slidable along the longitudinal axis 101, allowing the plug 132 to slide to open the check valve 130, while still being rotationally locked to the control tube 140. In particular, the rotational interlock surface(s) 138 of the plug 132 extend into the proximal end 145 of the control tube 140 to engage the rotational interlock surface(s) 147 of the control tube 140.

[0034] Still referring to Figure 8 , the control tube 140 can include one or more protrusions 148 that extend radially outward and are configured to engage a corresponding detent 184 (see Figure 10 ) to be discussed below. In the illustrated aspect, the control tube 140 includes two protrusions 148 spaced about 90° about the circumference of the control tube 140, although other arrangements are understood to be within the scope of the present disclosure.

[0035] Now referring to Figures 2-5 , Figure 8 and Figure 9 , an air distributor 150 having an aperture 151 (see Figure 5 ) is disposed about the control tube 140 and is pressed inside the barrel 102 during assembly of the hammer 100 due to the tightening torque. As such, the air distributor can not rotate relative to the barrel 102. The air distributor 150 includes a proximal flange 152 and a distal tube 153. The distal end 146 of the control tube 140 extends into the aperture 151 of the air distributor 150. At least one flange port 154 extends longitudinally through the proximal flange 152.

[0036] The air distributor 150 also includes a plurality of ports extending through the distal tube 153 and into the bore 151 to control airflow during operation of the hammer 100. That is, a plurality of proximal ports 155 extend radially through the distal tube 153 in respective alignment with the proximal ports 144 of the control tube 140. In some aspects, the plurality of proximal ports 155 can include eight ports, which, as in the illustrated aspect, are evenly spaced about the circumference of the distal tube 153. In other aspects, more or fewer proximal ports can be included, including a single proximal port 155.

[0037] A first plurality of distal ports 156 extends radially through the distal tube 153 at a location distal to the proximal port(s) 155. A second plurality of distal ports 156' extends through the distal tube 153 and distally beyond the first plurality of distal ports 156. The first plurality of distal ports 156 of the air distributor 150 is configured to align with a respective distal port 149 of the control tube 140 at at least one rotational position of the control tube 140. The second plurality of distal ports 156' of the air distributor 150 is configured to align with a distal port 149 of the control tube 140 at at least one rotational position of the control tube 140 that is different from the rotational position(s) at which the first plurality of distal ports 156 align with the distal port 149. In Figure 5 In the illustrated aspect, for example, the control tube 140 is rotated such that the second plurality of distal ports 156' align with the distal ports 149. In the illustrated aspect, the first plurality of distal ports 156 includes two ports positioned diametrically opposite one another on the distal tube 153 of the air distributor 150. Similarly, the second plurality of distal ports 156' includes two ports positioned diametrically opposite one another on the distal tube 153 of the air distributor 150 and 90° about the longitudinal axis 101 relative to the first plurality of distal ports 156. Thus, the first and second pluralities of distal ports 156, 156' are arranged in an alternating fashion about the circumference of the distal tube 153 of the air distributor 150. In other aspects, more or fewer first and second pluralities of distal ports 156, 156' can be included.

[0038] In the illustrated aspect, the second distal port 156’ is slot-shaped or oblong in shape such that the distal-most end of the second distal port 156’ extends distally beyond the first distal port 156. In the illustrated aspect, the proximal ends of the first distal port 156 and the second distal port 156’ are located at substantially the same longitudinal position along the air distributor 150 (i.e., the same distance from the proximal end of the air distributor 150), but this is not required. The longitudinal positions of the distal ports 156, 156’ can be selected to optimize operation of the hammer 100 for particular flow rates of air supplied to the hammer 100. In particular, the longitudinal position of the first distal port(s) 156 can be optimized for a first air flow rate, and the longitudinal position (i.e., the position of the distal-most end) of the second distal port(s) 156’ can be optimized for a second air flow rate. As mentioned, the second distal port 156’ extends distally beyond the first distal port 156, which means that the second distal port 156’ is optimized for a different air flow rate than the first distal port 156.

[0039] The air distributor 150 is disposed about the control tube 140 such that only the first distal port 156 or the second distal port 156’ is in fluid communication with a respective distal port 149 of the control tube 140 at a time. The distal end 146 (see Figure 5 ) of the control tube 140 is sealed against the aperture 151 of the air distributor 150, so air cannot flow through any distal ports 156, 156’ that are not aligned with a distal port 149. As described herein, the control tube 140 is rotatable relative to the air distributor 150 to control which of the distal ports 156, 156’ are aligned with the distal ports 149.

[0040] Referring now to Figures 2-5 and Figures 9-11 , the hammer 100 further includes a detent seat 180 that is rotationally and longitudinally secured to the barrel 102 by detents. The detent seat 180 is configured to bias the control tube 140 at a particular rotational position relative to the air distributor 150. In particular, the detent seat 180 includes at least one leaf spring 182 that is configured to engage a respective rotational interlock surface 147 of the control tube 140 to prevent rotation of the control tube 140 during operation of the hammer 100. In the illustrated aspect, the at least one leaf spring 182 includes four leaf springs, each of which engages a respective rotational interlock surface 147 of the control tube 140, but more or fewer leaf springs (including a single leaf spring) can be used. The leaf springs 182 are retained to tabs of the detent seat 180 by rivets, pegs, and / or pins 183.

[0041] The leaf springs 182 are oriented to exert an inwardly directed biasing force toward the longitudinal axis 101. The engagement between the leaf springs 182 and the rotational interlock surfaces 147 creates a limited rotational lock between the control tube 140 and the stop seat 180, and thus between the control tube 140 and the air distributor 150. However, if sufficient torque is applied to the control tube 140, the biasing force of the leaf springs 182 is overcome, thereby forcing the leaf springs 182 to deflect radially outward and allowing the control tube 140 to rotate relative to the stop seat 180. Continued rotation of the control tube 140 causes each leaf spring 182 to engage an adjacent rotational interlock surface 147. Thus, the control tube 140 has a plurality of indexable positions relative to the stop seat 180 and the air distributor 150.

[0042] Each of the indexable positions corresponds to the first distal port 156 or the second distal port 156' being in fluid communication with the distal port 149 of the control tube 140. That is, rotation of the control tube 140 relative to the air distributor 150 such that the leaf springs 182 engage the rotational interlock surface(s) 147 of the control tube 140 in different positions changes which set of distal ports 156, 156' is in fluid communication with the distal port 149 of the control tube 140. Thus, the relationship between the distal port 149 of the control tube 140 and the distal ports 156, 156' of the air distributor 150 facilitates adjustment of the air consumption of the hammer 100.

[0043] Reference is now made to Figure 10 The stop seat 180 also includes one or more stops 184 that are substantially coplanar with the protrusions 148 of the control tube 140 (as shown in Figure 8 The stop seat 180 can include two stops 184 spaced about 90° apart about the longitudinal axis of the stop seat 180, although other arrangements are understood to fall within the scope of the present disclosure. The stops 184 of the stop seat 180 are configured to limit rotation of the control tube 140 by engaging corresponding protrusions 148 of the control tube 140, thereby allowing the control tube 140 to rotate to an indexable position. In particular, rotation of the control tube 140 in a first direction (e.g., clockwise) is limited by engagement of at least one of the protrusions 148 of the control tube 140 with at least one of the stops 184. When such engagement occurs, the distal port 149 of the control tube 140 is placed in fluid communication with the first distal port 156 of the air distributor 150. Similarly, rotation of the control tube 140 in a second direction (e.g., counterclockwise) is limited by engagement of at least one of the protrusions 148 of the control tube 140 with at least one of the stops 184. When such engagement occurs, the distal port 149 of the control tube 140 is placed in fluid communication with the second distal port 156' of the air distributor 150.

[0044] Reference is now made to Figures 2-5Piston 160 is slidably disposed within barrel 102. In particular, piston 160 is arranged inside barrel 102 such that a first intermediate chamber 200 is defined between a proximal end of piston 160 and air distributor 150. Further, a bottom chamber 202 is defined between drill bit 120 and a distal end of piston 160. Piston 160 is configured to slide parallel to longitudinal axis 101 in response to a pressure differential between top chamber 166 and bottom chamber 202. Piston 160 defines a bore 164 that receives distal tube 153 of air distributor 150 at its proximal end and receives bottom valve 124 at its distal end. The proximal end of bore 164 includes a top chamber 166 and a proximal lip 168. Top chamber 166 has a larger inner diameter than the outer diameter of distal tube 153 of air distributor 150. Proximal lip 168 has an inner diameter that is substantially equal to the outer diameter of distal tube 153 such that proximal lip 168 forms a substantially air-tight seal with distal tube 153. The distal end of bore 164 has an inner diameter that is substantially equal to the outer diameter of bottom valve 124 so as to form a substantially air-tight seal with bottom valve 124. The portion of bore 164 distal of top chamber 166 has an inner diameter that is substantially equal to the outer diameter of distal tube 153 such that bore 164 forms a substantially air-tight seal with distal tube 153.

[0045] As shown in Figure 2 , piston 160 includes a sealing outer surface 161 having a diameter that is substantially equal to the inner diameter of bore 103 of barrel 102 so as to form a substantially air-tight seal with bore 103. The distal end of sealing outer surface 161 includes one or more flats 163 or other features that are radially recessed relative to sealing outer surface 161. Thus, when hammer 100 is assembled, flats 163 are spaced apart from the inner sidewall of bore 103, thereby allowing air to flow between flats 163 and the inner sidewall of bore 103 (see Figure 3 ). Piston 160 also includes an intermediate outer surface 165 proximal of sealing outer surface 161. Intermediate outer surface 165 has a reduced diameter relative to the sealing outer surface of the distal end of piston. Thus, when hammer 100 is assembled, intermediate outer surface 165 is spaced apart from the inner sidewall of bore 103 of barrel 102 (as shown in Figure 3 ), and intermediate outer surface 165 and bore 103 thereby define a second intermediate chamber 204 within barrel 102.

[0046] Still referring to Figure 2 , the proximal end of piston 160 includes one or more flats 167 or other features that are recessed inward from the outer diameter of piston 160. Flats 167 allow air to flow from first intermediate chamber 200 around the proximal end of piston 160 (i.e., between flats 167 and the inner sidewall of bore 103 of barrel 102) and into second intermediate chamber 204.

[0047] Industrial applicability

[0048] The disclosed aspects of the hammer 100 as set forth in this disclosure can be used to break and / or pulverize a ground surface, particularly a rock surface, during a drilling operation. In particular, the hammer 100 of the present disclosure generates repeated impact forces to break the ground surface to advance a drill string below the ground surface. The hammer 100 is configured to generate such impact forces with the drill bit 120 by cycling through various operating positions in response to the supply of pressurized air from a drill string (not shown) attached to the adapter 110. The hammer 100 generates these impact forces by reciprocating the piston 160 within the barrel 102 to impact the drill bit 120. In addition, the hammer 100 can be configured to rotate with the drill string attached to the adapter 110 to enhance drilling efficiency.

[0049] The hammer 100 can also be adjusted to be optimized for various air flow rates to enhance drilling efficiency.

[0050] Referring now to Figure 3 and Figures 12A-12E Operation of the hammer 100 during drilling proceeds generally as follows. Figure 3 and Figures 12A-12E depicts the rotational position of the control tube 140 in which the distal port 149 of the control tube 140 is aligned with the first distal port 156 of the air distributor 150. As will be appreciated from the following description, if the control tube 140 were instead aligned such that the distal port 149 of the control tube 140 is aligned with the second distal port 156' of the air distributor 150, the sequence of operation of the hammer 100 would be substantially the same as described herein, but the timing of the change in direction of the piston 160 would change. Starting with the position of the piston 160 shown in Figure 3 , air from the compressor opens the check valve 130 and flows into the first intermediate chamber 200. In addition, air from the compressor flows through the flat 167 of the piston 160 (see Figure 6 ), into the second intermediate chamber 204, through the recess 108 of the barrel 102, and into the bottom chamber 202. Air in the top chamber 166 of the piston can flow through the orifice 159 of the air distributor 150, into the bore 164 of the piston 160, through the bottom valve 124, through the bore 126, and finally out the exhaust port 128.

[0051] As air continues to flow into the bottom chamber 202 and out of the top chamber 166, a differential air pressure is created between the bottom chamber 202 and the top chamber 166. That is, the air pressure in the bottom chamber 202 exceeds the air pressure in the top chamber 166. As Figure 12AAs shown, this pressure difference causes piston 160 to slide proximally within cylinder 102. As piston 160 slides proximally, its opening 164 seals the orifice 159 of air distributor 150, thereby blocking the top chamber 166 of piston 160. Consequently, air can no longer flow from the top chamber 166 into the opening 164 towards the bottom valve 124. While piston 160 slides proximally, air from the first intermediate chamber 200 and the second intermediate chamber 204 (along with intake air from the compressor) can still flow through the recess 108 of cylinder 102 around the sealing outer surface 161 of piston 160 and into the bottom chamber 202.

[0052] like Figure 12B As shown, piston 160 continues to slide proximally until its sealing outer surface 161 engages the opening 103 of cylinder 102 near the recess 108. Consequently, air from the second intermediate chamber 204 can no longer flow around piston 160 into bottom chamber 202, blocking bottom chamber 202. Due to inertia, piston 160 continues to slide proximally, causing the air in the blocked bottom chamber 202 to expand and thus decrease in pressure. Simultaneously, the air in the first intermediate chamber 200 and the second intermediate chamber 204 becomes pressurized because the air in intermediate chambers 200 and 204, and the intake air from the compressor, can no longer flow around the sealing outer surface 161 of piston 160 into bottom chamber 202.

[0053] like Figure 12C As shown, piston 160 continues to slide proximally until bottom valve 124 is no longer sealed by opening 164 of piston 160. This allows air in bottom chamber 202 to flow through bottom valve 124, into opening 126, and out of exhaust port 128, as indicated by arrow 300. Piston 160's continued proximal sliding further increases the air pressure in the first intermediate chamber 202 and the second intermediate chamber 204.

[0054] like Figure 12D As shown, due to inertia, piston 160 continues to slide proximally until the first distal port 156 of air distributor 150 exits the proximal lip 168 of piston 160 and is in fluid communication with top chamber 166. Because of the fluid communication between the first distal port 156 and top chamber 166, air in the first intermediate chamber 200 can flow through the proximal port 155 of air distributor 150, into the opening 151 of air distributor 150, and exit through the first distal port 156 into top chamber 166. At the start of the power stroke, intake air from the compressor cannot flow to bottom chamber 202, but air can still be discharged from bottom chamber 202 via bottom valve 124. Intake air from the compressor flows into top chamber 166 via the first distal port 156. Consequently, the pressure in top chamber 166 increases.

[0055] likeFigure 12E As shown in FIG. 16B, as the air pressure in the top chamber 166 increases relative to the air pressure in the bottom chamber 202, the piston 160 stops moving proximally and begins moving distally. As shown in FIG. 16C, the piston 160 continues to move distally until the piston 160 contacts the bit 120, and the cycle repeats as long as the compressor continues to supply air to the hammer 100. As described above, the operational cycle of the hammer 100 is the same regardless of whether the control tube 140 is oriented such that the distal port 149 is aligned with the first distal port 156 or the second distal port 156’ of the air distributor 150. However, because the distal end of the second distal port 156’ of the air distributor 150 extends distally beyond the first distal port 156, the piston 160 does not need to travel as far proximally to place the second distal port 156’ of the air distributor 150 in fluid communication with the top chamber 166. Thus, the stroke of the piston 160 changes when the distal port 149 of the control tube is aligned with the second distal port 156’ of the air distributor 150. Figure 3 As shown in FIG. 16B, as the air pressure in the top chamber 166 increases relative to the air pressure in the bottom chamber 202, the piston 160 stops moving proximally and begins moving distally. As shown in FIG. 16C, the piston 160 continues to move distally until the piston 160 contacts the bit 120, and the cycle repeats as long as the compressor continues to supply air to the hammer 100. As described above, the operational cycle of the hammer 100 is the same regardless of whether the control tube 140 is oriented such that the distal port 149 is aligned with the first distal port 156 or the second distal port 156’ of the air distributor 150. However, because the distal end of the second distal port 156’ of the air distributor 150 extends distally beyond the first distal port 156, the piston 160 does not need to travel as far proximally to place the second distal port 156’ of the air distributor 150 in fluid communication with the top chamber 166. Thus, the stroke of the piston 160 changes when the distal port 149 of the control tube is aligned with the second distal port 156’ of the air distributor 150.

[0056] The hammer 100 is most effectively operated for certain air flow rates at the stroke timing associated with the second distal port 156’ being aligned with the distal port 149, and for different air flow rates at the timing associated with the first distal port 156 being aligned with the distal port 149. Thus, the operation of the hammer 100 can be optimized for a given air supply by aligning the distal port 149 of the control tube 140 with the appropriate one of the first distal port 156 and the second distal port 156’.

[0057] Figure 13 is a flowchart illustrating an example method 500 for adjusting the air consumption of the hammer 100. The method 500 can be performed as part of a setup operation prior to attaching the hammer 100 to a drill string in order to optimize hammer operation for a given air supply. The method 500 includes determining a target flow rate of air supplied to the hammer 100 at step 502. The target flow rate corresponds to the flow rate of air supplied by a compressor to which the hammer 100 and drill string are attached.

[0058] The method 500 also includes selecting a port in the air distributor 150 of the hammer 100 that corresponds to the target flow rate at step 504. Each of the set of distal ports 156, 156’ is optimal for a particular range of flow rates. That is, the first distal port 156 is optimal for a first range of flow rates, and the second distal port 156’ is optimal for a second range of flow rates. If the target flow rate determined at step 502 falls within the first range of flow rates, the first distal port 156 is selected. If the target flow rate determined at step 502 falls within the second range of flow rates, the second distal port 156’ is selected.

[0059] The method 500 further includes rotating the control tube 140 of the hammer 100 relative to the air distributor 150 at step 506 such that the distal port 149 of the control tube 140 is aligned with the port of the air distributor 150 selected at step 504. Rotating the control tube 140 is accomplished by rotating the plug 132 of the check valve 130 via the tool interface 136, which in turn rotates the control tube 140 via the connection of the rotating interlock surfaces 147, 138, as described herein. The control tube 140 is rotated in this manner until the distal port 149 of the control tube 140 is aligned with the port of the air distributor 150 selected at step 504. The leaf spring(s) 182 engage the rotating interlock surface(s) 147 of the control tube 140 to rotationally lock the control tube 140 relative to the detent seat 180 and the air distributor 150, thereby ensuring that the selected port of the air distributor 150 remains aligned with the distal port 149 of the control tube 140 during operation of the hammer 100. Once the selected port of the air distributor 150 is so aligned with the distal port 149 of the control tube 140, the adapter 110 can be connected to the drill string, and operation of the hammer 100 can begin. As described above, the engagement of the protrusions 148 of the control tube 140 with the detents 184 of the detent seat 180 provides a clear indication that the distal port 149 of the control tube 140 is aligned with the selected port of the air distributor 150. In particular, when the distal port 149 of the control tube 140 is aligned with the first distal port 156 of the air distributor 150, rotation of the control tube 140 (via the check valve plug 132) in a first direction (e.g., clockwise) causes at least one of the protrusions 148 to engage at least one of the detents 184. Thus, the operator receives tactile feedback that the distal port 149 and the first distal port 156 are aligned. Similarly, when the distal port 149 of the control tube 140 is aligned with the second distal port 156’ of the air distributor 150, rotation of the control tube 140 (via the check valve plug 132) in a second direction (e.g., counterclockwise) causes at least one of the protrusions 148 to engage at least one of the detents 184. Thus, the operator receives tactile feedback that the distal port 149 and the second distal port 156’ are aligned.

[0060] The hammer 100 and method of the present disclosure allow for adjustment of the control tube 140 to optimize actuation of the piston 160 for different flow rates of air supplied to the hammer 100. In particular, the air control tube 140 can be adjusted to control which of the distal ports 156, 156’ are in fluid communication with the distal port 149 of the control tube 140, thereby adjusting the timing of the piston stroke in which the piston 160 begins to travel distally toward the drill bit 120. Thus, the operating cycle of the hammer 100 can be tailored to the air supply, thereby improving the efficiency of the hammer over a range of air flow rates.

[0061] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed system without departing from the scope of the disclosure. Other embodiments of the system will be apparent to those skilled in the art from consideration of the specification and practice of the system disclosed herein. The specification and examples are intended to be exemplary only and the true scope of the disclosure is indicated by the following claims and their equivalents.

Claims

1. A hammer drill (100) comprising: a barrel (102) having a longitudinal axis (101) and defining a middle chamber (200, 204) and a bottom chamber (202); a piston (160) defining a top chamber (166) and slidable within the barrel (102) between the middle chamber (200, 204) and the bottom chamber (202), a control tube (140) having a distal port (149); and an air distributor (150) having a first distal port (156) and a second distal port (156'), wherein the control tube (140) is indexable between a plurality of rotational positions to adjust which of the first distal port (156) and the second distal port (156') of the air distributor (150) is aligned with the distal port (149) of the control tube (140).

2. The hammer drill (100) of claim 1, wherein the second distal port (156') of the air distributor (150) is distal of the first distal port (156) of the air distributor (150).

3. The hammer drill (100) of claim 1 or claim 2, further comprising a check valve plug (132) rotationally locked to the control tube (140).

4. The hammer drill (100) of any preceding claim, wherein the check valve (130) plug (132) comprises at least one rotational interlock surface, and wherein the control tube (140) comprises at least one rotational interlock surface (147) that engages the at least one rotational interlock surface (138) of the check valve plug (132) to rotationally lock the check valve plug (132) to the control tube (140).

5. The hammer drill (100) of any preceding claim, wherein the at least one rotational interlock surface (138) of the check valve plug (132) forms a sliding fit with the at least one rotational interlock surface (147) of the control tube (140) to allow the check valve plug (132) to longitudinally slide relative to the control tube (140).

6. The hammer drill (100) of any preceding claim, further comprising: a detent seat (180) fixed to the barrel (102), wherein the detent seat (180) comprises at least one leaf spring (182), wherein the control tube (140) comprises at least one rotational interlock surface (147), and wherein engagement of the at least one leaf spring (182) with the at least one rotational interlock surface (147) rotationally locks the control tube (140) in one of the plurality of rotational positions.

7. The hammer drill (100) of claim 6, wherein rotation of the control tube (140) relative to the air distributor (150) causes each of the at least one leaf spring (182) to deflect radially outward and engage an adjacent one of the at least one rotational interlock surface (147).

8. A hammer drill (100) according to any preceding claim, wherein the check valve plug (132) comprises a tool interface (136) for receiving a tool for rotating the check valve plug (132).

9. A hammer drill (100) according to any preceding claim, further comprising: an adapter (110) connected to the proximal end (104) of the barrel (102) for receiving inlet air, wherein the tool interface (136) of the check valve plug (132) is accessible via the adapter (110).

10. A hammer drill (100) according to any preceding claim, wherein the rotation interlock surface (147) of the control tube (140) is a substantially flat surface arranged in a square configuration about the longitudinal axis (101), and wherein the rotation interlock surface (138) of the check valve plug (132) is a substantially flat surface arranged in a square configuration about the longitudinal axis (101).

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