Patent Application
20240254860
Virtually all hydraulic rock drilling tools use a piston for providing a mechanical impulse to a rock breaking tool and a control valve which redirects fluid flow to cause the piston to oscillate to and from the tool. The means with which to couple piston position to the control valve is a critical design feature. The most common prior art includes piston ports which direct fluid pressure to and from a valve control surface. This form of control can be problematic as porting surfaces are usually large in diameter to enclose the piston which causes excessive leakage, and mechanical shock from the impulse can cause lateral motion and component wear at the porting interfaces. Additionally, in downhole applications the piston and valve must fit within a confined diameter as determined by the hole being drilled. Valves which enclose the piston consume precious radial space.
According to an exemplary embodiment, the subject disclosure relates to a down-the-hole drill hammer including a drill bit about a distal end of the drill hammer and a piston for percussively contacting the drill bit. The down-the-hole drill hammer comprises: a drill bit; a piston for percussively contacting the drill bit; a valve assembly for controlling the supply of drive fluid to and from the piston, the valve assembly comprising: a piston follower valve moveable within the valve assembly independently from the piston.
According to another aspect, the valve assembly further includes: a valve housing; and a control valve moveable within the valve housing. The valve housing is mounted within a valve control area and the control valve and piston follower valve are each movable relative to the valve housing. The piston follower valve is moveable relative to the control valve. The valve housing includes galleries configured for fluid communication with supply ports, drive ports and/or exhaust ports. The valve housing includes a central through hole having a proximal end portion and a distal end portion, and wherein the distal end portion has a larger internal diameter than an internal diameter of the proximal end portion. The valve housing includes a plurality of galleries along its outer surface in fluid communication with an internal central through hole. The valve housing includes at least three through holes spaced apart in a longitudinal direction along a longitudinal length of the valve housing. The valve housing includes a proximal end portion having a substantially pentagram-shaped cross-section. The control valve includes galleries configured for fluid communication with the valve housing galleries. The control valve includes a first gallery and a second gallery spaced from the first gallery. The control valve includes a longitudinal through hole coaxial with a longitudinal axis of the control valve. The control valve includes a distal end face having an overall diameter larger than a proximal end face. The piston follower valve is movable relative to the piston. The piston follower valve is movable relative to the valve housing and the control valve. The piston follower valve is a cylindrical valve. The piston follower valve includes a first annular portion occluded at about a midportion via an occlusion and a second annular portion. The first annular portion includes a plurality of slots circumferentially spaced apart and in fluid communication with an interior of the first annular portion. The piston follower valve is movable between a first position wherein the plurality of slots is occluded and second position wherein the plurality of slots are not occlude and in fluid communication an external of the piston follower valve. The second annular portion includes a plurality of through holes circumferentially spaced apart and in fluid communication with an interior of the second annular portion. The piston follower valve is movable between a first position wherein the plurality of through holes is occluded and second position wherein the plurality of through holes are not occlude and in fluid communication an external of the piston follower valve.
In accordance with another exemplary embodiment, the present disclosure provides for a valve assembly for a down-the-hole drill hammer comprising: a valve housing; a control valve mounted within and movable relative to the valve housing; and a piston follower valve moveable relative to the valve housing and control valve.
Generally, the subject disclosure relates to a downhole drill having a piston follower design in which the valve porting is coupled to the piston position with a follower stem. This stem is also positioned axially above the piston and does not consume radial space beyond that required by the piston.
In an exemplary embodiment the piston follower valve (PFV) control is used in a hydraulic down-the-hole drill intended to operate on high pressure (e.g., 2000 psi) hydraulic fluid such as, e.g., water. The PFV is pressurized in a manner such that it follows piston motion and provides a small portion of a constant downward (toward impact) force. A control valve has two oppositely facing areas (a constant supply area and a larger control area) and volumes that control its motion. The control area is ported by the PFV along an inner bore of the valve cyclically between high pressure and low pressure as the PFV follows the piston motion up and down.
Other features and advantages of the subject disclosure will be apparent from the following more detailed description of the exemplary embodiments.
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.
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.
“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.
“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.
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.
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.
Referring to
As best shown in
The valve housing 24 is configured as best shown in
Referring to
The proximal end portion 36 includes a plurality of through holes 42a-e circumferentially spaced apart and in fluid communication with the central through hole 32 and external gallery 34a. In the present example, the proximal end portion includes 5 through holes, but can alternatively include more or less e.g., 1, 2, 3, 4, 6, 7, 8, 9, 10 or more through holes. The mid-portion 38 includes a plurality of through holes 44a-e circumferentially spaced apart and in fluid communication with the central through hole 32 and external gallery 34b. In the present example, the mid-portion includes 5 through holes, but can alternatively include more or less e.g., 1, 2, 3, 4, 6, 7, 8, 9, 10 or more through holes. The distal end portion 40 includes a plurality of through holes 46a-e circumferentially spaced apart and in fluid communication with the central through hole 32 and external gallery 34c. In the present example, the distal end portion includes 5 through holes, but can alternatively include more or less e.g., 1, 2, 3, 4, 6, 7, 8, 9, 10 or more through holes.
Referring to
The control valve 26 is configured as best shown in
The overall diameter of the control valve 26 is sized and configured to move or slide within the valve housing 24. The control valve itself has two end faces, a proximal end face 56 and a distal end face 58 which differ in overall diameter. The proximal end face 56 is proximally facing or supply facing (i.e., facing the supply fluid entering the drill hammer) and has an overall diameter B that is smaller than an overall diameter B′ of the distal end face 58 which is a distally facing end or alternatively referred to as a control face. The overall diameter B of the control valve remains constant throughout the length of the control valve except at the distal end face 58. In other words, the distal end face 58 includes a radially extending flange having an overall diameter B′ that is greater than the overall diameter of the remainder of the control valve. The overall length i.e., the overall axial length, of the control valve is smaller than an overall length of the valve housing. In other words, the overall length i.e., the overall axial length of the valve housing is larger than an overall length of the control valve.
The PFV 22 is configured as best shown in
Referring back to
The porting assembly 30 is a series of ports or fluid passageways for the passage of working fluids through the drill hammer to drive percussive operation thereof. In the present exemplary embodiment, the porting assembly includes a supply inlet 100, supply ports 102, drive ports 104, and exhaust ports 106 (
The valve assembly 20 is mounted within the drill hammer as best shown in
In the return stroke configuration (
In the drive stroke configuration (
In operation, working fluid is supplied to the drill hammer through supply inlet and the supply side or proximal end of the valve assembly is always pressurized to provide a force to push the control valve and PFV distally or downwardly towards the drill bit end of the hammer. The distal end or control side of the valve assembly is alternatingly supplied by supply or exhaust pressure fluid. When the piston moves downwardly, working fluid pressures pass through the supply ports and drive ports and through the valve housing. When the piston moves upwardly, exhaust pressures pass through the valve housing and the exhaust ports.
The PFV is free to move independently of the piston, i.e., the PFV is unconnected to the piston. However, owing to the supply pressures and motion of the piston, the PFV is moved in part by the piston and supply pressures during operation of the hammer and thereby “follows” the piston. The PFV is designed to allow valve porting based on piston position. Further, the volume at the proximal end of the piston where PFV contacts the piston is always exposed to exhaust pressure. The piston follower valve is movable relative to the piston and is moveable relative to the valve housing and the control valve. Additionally, the piston follower valve is movable between a first position wherein the plurality of slots is occluded and second position wherein the plurality of slots are not occlude and in fluid communication an external of the piston follower valve. Further, the piston follower valve is movable between a first position wherein the plurality of through holes is occluded and second position wherein the plurality of through holes are not occlude and in fluid communication an external of the piston follower valve.
In the drive stroke phase, supply pressure moves the control valve distally within the valve housing. Then, as the PFV moves downwardly, the PFV slots communicate with the valve control area thereby filling the valve control area with supply pressure and moving the control valve upwardly, and then the cycle repeats. The distally facing end of the control valve defining the valve control area is larger than the proximally facing end of the control valve. During the return phase, when the PFV moves upwardly the PFV slots become occluded by the control valve and the PFV through holes fluidly connect with the valve control area exhausting the pressures within the valve control area thereby allowing the supply pressure to move the control valve back downwardly. This movement of the PFV, which follows movement of the piston, thereby controls positioning of the control valve and pressures applied to the piston via the drive ports and exhaust ports.
Referring back to
In accordance with another exemplary embodiment, the present disclosure provides for a valve assembly for a down the a down-the-hole drill hammer that includes a valve housing, a control valve mounted within and movable relative to the valve housing, and a piston follower valve moveable relative to the valve housing and control valve. The valve assembly can be e.g., the valve assembly 20 as described above.
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.
This application claims the benefit under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 63/482,647, filed Feb. 1, 2023, and entitled “Down-The-Hole Drill Hammer Having A Piston Follower Valve,” the entire disclosure of which is hereby incorporated by reference for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 63482647 | Feb 2023 | US |
