Liquid operated drilling device

Abstract

The present invention relates to a liquid operated drilling device (1) for drilling a hole (100), where the drilling device (1) comprises: a hammer (9) for forming a hole by a rotational and percussive movement; a rotating device (50) for rotating the hammer (9); and a hollow drill rod (46) for connecting the rotating device (50) with the hammer (9) and for delivering pressurized liquid to the hammer (9) in order to generate an impact movement of a drill bit (24) of the hammer (9) wherein the hammer (9) comprises: a tubular body (10) having a hollow interior (12), an upper portion of which receives working pressure (PT) liquid and a lower portion of which is open to a back pressure (P0); an actuator cylinder X having a piston rod (15) extending therethrough inside the body (10), where the piston rod (15) acts as an impact piston (52) that uses a drill bit (24) in its lower portion (60); an oscillating valve mechanism (Y) based on a mechanical slide (76), comprising a valve channel leading into a working pressure space and a back pressure space, which alternately leads a working pressure PT and a back pressure P0 into a second space portion (42) of the piston; and a channel (23, 34) formed in the piston rod (15) for continuously conducting the working pressure PT through the piston rod (22) into a space portion (40) below the piston (32). According to the invention, there is at least one yielding part (26) between the upper part (22) and the lower part (60) of the piston rod (15) and a movement limiter (28) which limits the movement path of the upper part (22) and the lower part (60) relative to each other.

Description

Technical Field

[0001] The present invention relates to a fluid-operated drilling apparatus for drilling, as described in the preamble of claim 1. Background Technology

[0002] According to existing technology, a liquid-operated impact hammer is rotated via a drill pipe, thereby delivering pressurized drilling fluid to the impact unit to generate impact motion for drilling in relatively hard formations or in mixed formations of hard and soft formations. Within the hammer, the same drilling fluid carries drill cuttings away from the surface of the drilling tool and at least partially cleans the borehole. The drill pipe is configured to generate rotational motion within the impact hammer, and includes a reciprocating piston that impacts a drill bit attached to the impact hammer, wherein the drill bit is capable of moving a given preselected length along the longitudinal direction of the impact hammer body. Water or drilling fluid may contain additives that enhance the ability to deliver drill cuttings out of the hole or help support the borehole. The hammer includes a tubular body with a hollow interior. The hammer has a rear end capable of connecting to a drill pipe, the rear end including at least a hydraulic supply channel for delivering pressurized fluid to the impact hammer. An impact piston is located inside the impact hammer and can impact the lower portion of the impact drill bit being drilled.

[0003] Water hammers, such as Wassara hammers, are known and include: a valve; a lower pressure chamber that causes a piston to rise to its upper load position; and an upper chamber that regulates the cycle of the drill bit striking the piston, the cycle being controlled by a valve system located in the upper part of the impact hammer.

[0004] Prior art document US20070261869A1 discloses a water hammer in which a valve system is primarily located in the upper portion of the water hammer. The water hammer has a valve section that forms first, second, and third spatial portions, which cause the impact motion of the water hammer. When this structure is used with a pressurized working fluid of high viscosity (e.g., mud or oil) or a pressurized working fluid containing solids, the pressurized fluid flows into these spatial portions through channels. The diameter of these channels is significantly smaller than the diameter of the hydraulic supply channels for the supplied fluid. As the fluid flows into these smaller diameter channels, the fluid velocity increases. A high-viscosity fluid or a fluid containing solids and with high velocity will cause significant friction on the channel walls, thus having an abrasive effect on the walls. This effect is even greater in cases where the fluid contains solid particles (e.g., mud). This abrasive effect leads to rapid wear of the internal components of the hammer and shortens the hammer's service life.

[0005] Moreover, when using this structure, especially with the piston having the largest possible diameter, it is difficult to provide flushing in a way that keeps the components inside the hammer clean, as flushing hardly occurs inside the hollow interior of the tubular body. The large piston also causes a relatively large amount of water to move back and forth, which reduces efficiency and makes sealing the hammer difficult. The back-and-forth movement of a large amount of water also contaminates the hammer with drill cuttings as well as small fragments of rock and sand. In this structure, there is a continuous hollow section extending through the piston from one end to the other, which effectively guides the working fluid away from the impact unit and makes it difficult to guide the fluid through the hammer to effectively lubricate other components of the system. Furthermore, in such a system, all external particles remain in the water hammer because the hammer rotates and the particles cannot be expelled (except through the sealing area), thus damaging the seal during the process. This problem also affects structures in which an adjustable pressure barrier is arranged in the lower part of the water hammer to accommodate the movement and suction of the oversized piston, as the piston also causes a suction effect and increases the intake of foreign matter into the water hammer.

[0006] US Patent 11,306,538B2 discloses the applicant's early attempts in developing a drilling device with a front section structure. However, the results showed that the performance of the drilling device was unsatisfactory. The internal components of the hammer were preferably assembled from two or more parts, the durability of the joints was unsatisfactory, and the actuator was subjected to impact loads.

[0007] Furthermore, neither the piston size nor leakage from the sliding mechanism was considered. In this case, the hammer rises slowly, and the clearance of the sliding mechanism is crucial. Too much clearance will lead to unstable operation, or even the sliding mechanism jamming.

[0008] Furthermore, the two-piece piston rod, which proved advantageous due to its assembly, presented new problems at the joint between the components. After a period of time, significant impacts damaged the pin joint, as the pin size could hardly be increased. Summary of the Invention

[0009] The object of this invention is to develop a fluid-operated drilling apparatus for drilling, which significantly improves the durability of the hammer, particularly the actuator. Another object of this invention is to provide a fluid-operated drilling apparatus that is easier to manufacture than drilling apparatuses according to the prior art. The distinctive features of the invention are set forth in the appended claim 1.

[0010] This objective is achieved by a fluid-operated drilling apparatus for drilling, comprising: a hammer for forming a hole by rotational and impact motion; a drill bit configured to strike the hammer; a rotating device for rotating the hammer; and a hollow drill rod for connecting the rotating device to the hammer and for delivering pressurized fluid to the hammer to generate the impact motion of the hammer and the drill bit. The hammer comprises: a tubular body having a hollow interior, an upper portion, and a lower portion, wherein the upper portion receives working-pressure fluid, and the lower portion opens to back pressure; and an actuator cylinder having a piston rod extending through the actuator cylinder within the body. The actuator cylinder further comprises: a cylinder barrel including a top end at the upper end and a bottom end at the lower end in the operating position of the drilling apparatus; and a piston having an annular surface region that axially divides the annular space between the top and bottom ends into a lower working space and an upper working space between the cylinder barrel and the piston rod. The piston rod is configured to function as an impact piston, thereby enabling the use of a drill bit in the lower portion of the piston rod. The piston rod has a cross-sectional surface area A in a channel passing through its bottom end. The piston rod includes an upper portion and a lower portion connected to each other. Furthermore, the hammer includes an attachment frame in the upper portion of the actuator cylinder, which attaches the actuator cylinder to the body. In the operating position, the attachment frame separates the upper working pressure space from the lower back pressure space. The upper portion of the piston rod extends into the working pressure space, and the lower portion of the piston rod transmits blows to the drill bit. The oscillating valve mechanism based on a mechanical slider includes valve channels leading to the working pressure space and the back pressure space, which alternately guide the working pressure and back pressure into the working space above the piston, and channels formed in the piston rod for continuously transmitting the working pressure through the upper portion of the piston rod to the working space below the annular piston. Between the upper and lower portions of the piston rod, there is at least one yielding member and a motion limiter located between the upper and lower portions.

[0011] Compared to rigid joints according to the prior art, the yield joint (which is flexible along the axial direction of the piston rod) between the piston rod sections in the drilling apparatus according to the invention allows for several advantages. When the piston's direction of movement changes, the yield joint reduces the stress acting on the locking components of the joint, thus reducing vibration in the hammer, i.e., acting as a shock absorber. This reduces hammer wear and lowers the precision requirements for manufacturing the piston components in terms of their axial dimensions. Furthermore, the hammer's piston can be driven very close to the calculated impact point because its yielding capacity can prevent highly abrasive impacts. Overall, the yield joint provides a favorable joint.

[0012] By manufacturing the piston rod in two separate parts, these parts are easier to manufacture and can be repaired individually. A single, long piston rod would be difficult to machine, especially difficult to harden to the correct dimensions, difficult to transport, and difficult to repair. Since most of the complex flow channels and valve structure are contained in the upper section of the piston rod, this upper section is prone to wear caused by the working fluid. The lower section, with its simpler structure, is less prone to wear and can be used for a longer period before replacement. When using separable upper and lower sections, the upper section can be decommissioned earlier while the lower section remains in use. In addition to the advantages mentioned above, the piston seal is easier to install because the lower section, with a diameter larger than the piston seal (which surrounds the upper section of the piston), can be removed from the upper section in conjunction with the installation of the piston seal. This allows for the use of more durable continuous annular seals.

[0013] At the end of the stroke, the kinetic energy of the upper part is reduced by the yielding component.

[0014] The embodiment using an auxiliary piston provides a longer yield distance, which ensures that the operation of the valve at the dead point is not affected by impact stress.

[0015] The auxiliary piston of the piston rod, located between the upper and lower portions, receives only the pressure difference because the yielding component is disposed between these portions, and the annular surface area below the piston rod is preferably effectively flushed by an opening formed in the back pressure space.

[0016] The static pressure difference between the pressure chamber and the lower back pressure pushes the auxiliary piston outward to its end position during impact and return motion. When the hammer encounters the drill bit, the auxiliary piston begins to move inward, thus the kinetic energy of the upper portion is reduced by the excessive pressure in the pressure chamber relative to the working pressure. This excessive pressure is mainly generated by flow resistance when the chamber is suddenly emptied through the supply channel, and to a lesser extent by the elasticity of water and the inertia of mass.

[0017] Similar excessive pressure can be generated when the pressure chamber covers the entire lower surface of the piston rod, but the yield distance is more difficult to adjust and can easily end up being too short.

[0018] The kinetic energy generated by the impact is only minimally reduced by the compression of the water, but it provides the force that propels the water. The pressure required to decelerate over the remaining distance is primarily generated by throttling the outlet channel. Therefore, the outlet / inlet channel contributes to the elastic effect by throttling the outflow.

[0019] The elasticity of water remains linear up to 1000 bar, so it does not change too much with increasing borehole depth.

[0020] The dimensions of the pressure chamber and flow passage in the drilling apparatus are preferably configured to achieve a yield distance that ensures trouble-free operation of the valve mechanism. Therefore, the dimensions of the pressure chamber and flow passage can vary significantly, as long as the operation of the valve mechanism remains undisturbed.

[0021] In this application, relative terms (e.g., "lower part," "uppermost side," and "lowermost side," "top" and "bottom") refer to the normal operating position of the hammer on a flat surface. For example, "lower part" refers to a position closer to the drill bit than "upper part."

[0022] The upper and lower portions of the piston rod are continuous along its longitudinal direction. This allows the piston to be manufactured from shorter components, making it easier to transport to the drilling site.

[0023] Preferably, the motion limiter is formed by a groove and a locking member, wherein the groove is tangent to both the upper and lower portions and substantially transverse to the longitudinal direction of the piston rod. In this embodiment, compressive force acts on the locking member, which can withstand even continuous loads.

[0024] Preferably, the groove is tangent to both the upper and lower portions and substantially transverses the longitudinal direction of the piston rod. Therefore, the groove and locking mechanism do not occupy the space in the middle of the piston rod, but rather...

[0025] Preferably, the cross-sectional length of a hole along the longitudinal direction of the piston (at least at the convex portion) is greater than the cross-sectional width of the hole along the transverse direction of the piston, thereby allowing the locking pin to have a degree of freedom of movement in the hole along the axial direction of the piston.

[0026] Preferably, the locking component is a locking pin arranged in a slot that limits the range of movement of the upper and lower portions relative to each other.

[0027] Preferably, the yield limiter is implemented in such a way that the groove has a gap relative to the locking member arranged in the hole so as to enable the yielding action.

[0028] The gap can be 0.5-15 mm, preferably 3-10 mm. When the locking member moves within the hole gap, this gap provides sufficient yielding movement when the yielding member is compressed. However, typically, the locking member cannot swing freely within the hole because the yielding member presses the locking member against the side of the hole.

[0029] Preferably, the yielding element is hydraulic. Hydraulic yielding elements withstand impacts well and are therefore very reliable.

[0030] Preferably, the cross-sectional length of a hole along the longitudinal direction of the piston (at least at the convex portion) is greater than the cross-sectional width of the hole along the transverse direction of the piston, thereby allowing the locking pin to have a degree of freedom of movement in the hole along the axial direction of the piston.

[0031] Preferably, the cylinder actuator includes a hydraulically auxiliary piston connected to a hydraulically yielding component. This hydraulically auxiliary piston is arranged between the upper and lower portions together with the upper portion of the piston rod, and is configured to transmit the impact force downwards to the heavy lower portion of the piston rod and to the drill bit, so that the actuator and other components belonging to the upper portion are not subjected to excessive mechanical stress. In the drilling apparatus according to the invention, the actuator generates a reciprocating impact motion transmitted to the lower portion, which weighs, for example, 200 kg, and impacts the drill bit. The upper portion can have a mass of, for example, 100 kg, so that when the auxiliary piston is used, the stress and gravity acting on the upper portion are not as high as when the lower portion is directly impacted by the upper portion.

[0032] When the diameter of the supply channel is 12mm, the upper part, which weighs 100kg, moves at a stroke rate of 150 strokes per minute, giving a speed of 15m / s. The upper part can be stopped by a hydraulic yielding element with a diameter of 60mm and a height of 10mm.

[0033] The actuator stroke speed is preferably increased to such an extent that even large gaps in the mechanical sliding parts are not a problem. The flow resistance in the gap formed by the gap increases to the fourth power of the speed. The actuator stroke frequency is set in the range of 100-400 strokes per minute, with 150-250 strokes per minute being the most preferred.

[0034] The hammer preferably includes a piston rod seal, which is a continuous annular seal located between the attachment frame and the upper portion of the piston rod.

[0035] The drilling depth does not affect the performance of the drilling device according to the invention in any way similar to the aforementioned Wassara drilling device. Regardless of the drilling depth, the piston force of the actuator remains constant in both directions. For example, at a depth of 1000 m, the back pressure is 100 bar, therefore the working pressure supplied by the 100 bar pump pressure is 200 bar, a difference of 100 bar. The same piston force acts in both directions when the annular surface area of ​​the piston is twice the surface area of ​​the piston rod. Attached Figure Description

[0036] The present invention will now be described in detail with reference to the accompanying drawings, which illustrate some embodiments of the invention. In the drawings:

[0037] Figure 1This is a side view of a drilling apparatus according to a first embodiment of the present invention.

[0038] Figure 2 This shows a cross-sectional view of the cylinder actuator components before assembly.

[0039] Figures 3a-3c This is a cross-sectional view showing the operation of the oscillating cylinder actuator.

[0040] Figure 4a and 4b This diagram illustrates a cross-sectional view of the actuator's operational phases.

[0041] Figure 5 A cross-sectional view showing details of the operation of the actuator's piston rod and slider.

[0042] Figure 6 This diagram shows a cross-sectional view of one embodiment of a hydraulic yielding component, which is coupled to a piston rod component joint.

[0043] Figure 7a and 7b This is a cross-sectional view of the two yielding ends of the yielding member according to the second preferred embodiment. Detailed Implementation

[0044] The following reference numerals are used in the accompanying drawings to indicate the features shown in the drawings:

[0045] 1 Drilling equipment

[0046] 1.2 Drilling tower

[0047] 9 impact hammers

[0048] 10 main bodies

[0049] 12 hollow interior,

[0050] 15 Piston Rod

[0051] 14 backends

[0052] 16. The upper part of the main body

[0053] 18 fluid pressure supply channels

[0054] 20 cylinder bottom end

[0055] Top of 20' cylinder

[0056] 22 Upper part of piston rod

[0057] 22.1 Pressure Channel

[0058] 22.2 Working space, i.e., pressure chamber

[0059] 22.3 Inclined Channel

[0060] 22.5 locking pin

[0061] 22.6 Auxiliary piston of hydraulic yielding component

[0062] 22.7 Circular Space

[0063] 22.8 Auxiliary Channel

[0064] 23. Second fluid pressure supply channel in the piston rod

[0065] 24 drill bits

[0066] 26 Yielding Components

[0067] 28 motion limiters

[0068] 32 pistons

[0069] 33 Second valve channel

[0070] 34 radial supply channels

[0071] 35 axial outlet channel

[0072] 36 slots

[0073] 37 Locking Components

[0074] 38 Lateral slots

[0075] 40 First Space Section

[0076] 42 Second Space Section

[0077] 44 fluid booster units

[0078] 45 Working pressure space

[0079] 46 drill pipe

[0080] 50 Rotary Device

[0081] 52 Impact Piston

[0082] 54. Passage through the bottom

[0083] 56 Annular Seal

[0084] Replacement design for 58 pressure channels

[0085] The lower part of the 60 piston rod

[0086] The upper plug of the 66 piston, i.e., the sliding guide.

[0087] 74 Blocking Zone

[0088] 76 valve sliding parts

[0089] The first working length of the 76a slider

[0090] The second working length of the 76b slider

[0091] 77 First Valve Channel

[0092] 80 cylinder barrel

[0093] 85-inch perforated attachment frame

[0094] 86 Attached frame bottom end

[0095] 86' top of the attachment frame

[0096] 100 holes

[0097] 102 Ground

[0098] Surface area of ​​piston rod 22

[0099] Surface area of ​​B-ring piston

[0100] Valve unit in Y actuator

[0101] X entire oscillating cylinder actuator

[0102] RR proposed threaded joints in impact pistons

[0103] P T Work pressure

[0104] P p Pump pressure

[0105] P o Back pressure below the drill bit

[0106] like Figure 1 As shown, the main components of the tracked drilling device 1 according to the present invention are a drill tower 1.2, a drill rod 46, a hammer 9 for forming a hole 100 in the ground 102, and a liquid-operated rotating device 50 for rotating the hammer 9.

[0107] Hammer 9 includes a specific oscillating actuator X for generating an impact and a drill bit 24.

[0108] Fluid pressure can be used to lubricate hammer components, flush boreholes, and eject debris from the hammer. The rotating mechanism can be driven by an electric motor, or it can be fluid-operated. Positioning tubes are typically located in the borehole behind the drill pipe. Figure 1 In the drilling apparatus 1 shown, the rotating device 50 rotates the drill rod 46, which in turn rotates the hammer body 10 (outer cylinder). The body 10 then rotates the drill bit, while the hammer actuator causes the drill head (i.e., the drill bit) to reciprocate.

[0109] The components of the oscillating cylinder actuator are Figure 2 The cylinder 80 shown has a top end 20' at its upper end and a bottom end 20 of the upper portion 22 that guides the piston rod 15. The bottom end 86 of the attachment frame 85 securely attaches the cylinder 80 to the outer cylinder, i.e., to the body 10. In other words, the perforated attachment frame 85 is attached to the bottom end 20. Although... Figure 2 This indicates a piston rod 15 without a yield joint, but it should be understood that the piston rod includes a yield joint.

[0110] like Figures 3a-3c As shown, the axial outlet channel 35 extends into the second valve channel 33 in the upper portion to provide back pressure to the actuator in a controlled manner. The second pressure supply channel 23 is inside the piston rod and leads to the supply channel 34, which continuously transmits the working pressure to the region below the annular piston 32.

[0111] The slider 76 moves around the piston rod 15 and closes the supply channel at both ends of its range of motion. This supply channel always leads to the first working pressure space portion 40, or preferably to the second back pressure space portion 42. The space portion can also be referred to as the working space. Working sections 76a and 76b, constructed in the piston 32 of the piston rod 15, are indicated in the slider 76. Preferably, the radial clearance of the slider 76 relative to the valve channel toward the cylinder 80 is eliminated by a single flexible seal. The clearance toward the annular piston is preferably 0.2-10 mm radially, and most preferably 0.5-3 mm.

[0112] Figure 4a and 4b To illustrate very illustratively, for example, at a depth of one kilometer, the back pressure is 100 bar. The pump pressure can be, for example, 80 bar. Therefore, according to formula P... T =P P +P0, the working pressure in this case is 180 bar. The working pressure at this depth is approximately the pump pressure, i.e., 80 bar (=180-100 bar).

[0113] The working pressure is continuously guided along the second pressure supply channel 23 and the radial supply channel 34 to the area below the piston 32. The valve mechanism Y alternately guides water at either back pressure or working pressure into the second space section 42 according to the selected cycle.

[0114] Figure 3a , 3b 3c illustrates the working principle of the oscillating actuator X. Figure 3a In the case shown, there is a working pressure P in the first space portion 40 below the piston 32. tA back pressure P0 exists in the second space portion 42 above the piston 32. When the surface area B of the annular piston 32 is twice the surface area A of the piston rod 15 (i.e., the opening in the bottom end 20 of the cylinder 80), the piston 32 begins to lift the upper portion 22 of the piston rod 15. Figure 3b In the middle, the piston 32 has risen, thus opening the first channel 33 opposite to the slider 76 (which is guided from the first space portion 40 to the second space portion 42), causing the lifting force to stop, and the remaining resultant force is only the working pressure P resisting the back pressure applied to the surface area A of the upper portion 22 of the piston rod. t .

[0115] Figure 2-4b The two-part structure of the piston rod is not shown, but it should be understood that the piston rod always has such a two-part design.

[0116] The surface region B (i.e., the annular surface region) of the piston 32 is preferably 110-400% of the cross-sectional surface region A of the lower portion 60 of the piston rod, and most preferably 150-300%.

[0117] like Figure 3c As shown, when the slider 76 opens the second valve channel 33 in the passage and closes the channel from the first space portion 40, the downward movement stops, causing the second space portion 42 to be filled with back pressure. The cycle begins from the start. The speed of the cycle is affected by the dimensions of the slider and its corresponding portion, particularly by the clearance used. As shown in Figure 4, the lower end of the slider 76 includes a blocking region 74, which closes the channel between the first space portion 40 and the second space portion 42 when the piston 32 (i.e., the annular piston) reaches its region. Preferably, the blocking region 74 is ribbed.

[0118] It is difficult to manufacture the entire upper portion and its heavy lower portion 60 of the piston rod as a single piece. Therefore, assembling them from two or more parts is technically advantageous in terms of manufacturing, but fixed joints introduce inconvenient structural problems. For example, rigid pin joints cannot withstand impact loads for extended periods. Figure 6In this design, the upper portion 22 of the piston rod is attached to the lower portion 60 of the piston rod by a transverse pin 22.5 that limits the range of motion, and a hydraulic yielding member 26 is located between the two portions. The lower surface of the upper portion 22 of the piston rod faces the working space 22.2, i.e., the pressure chamber, into which the working pressure is guided through pressure channels 22.1 and inclined channels 22.3. The diameter of the channels is 3.5-40% of the diameter of the upper portion 22 of the piston rod, preferably 10-30%. As the stroke speed increases, the flow resistance in the narrow channels becomes quite large. An impact piston 52 for impacting the drill bit 24 is formed in the lower portion of the piston rod 60. The yielding distance can be extended by widening the pressure channels (reference numeral 58).

[0119] exist Figure 7a and 7b A further developed version of the hydraulic yielding component 26 is shown in the figure. The rest of the structure is the same as described above, except that the auxiliary piston 22.6 in the lower end of the upper portion of the piston rod 22 is shown in a compressed state. The auxiliary piston 22.6 preferably includes an annular seal 56, which... Figure 7a and 7b The auxiliary piston 22.6 has a range of axial movement of a selected length. A motion limiter 28 is provided, which is preferably formed by a locking pin 22.5 and a groove 36 (as an offset lateral slot 38) formed between the upper portion 22 and the lower portion 60 of the piston rod 22, such that a larger pressure channel 22.1 can extend directly from the end of the radial supply channel 34 into the working space 22.2 arranged above the auxiliary piston 22.6. As shown, the motion limiter 22.5 is preferably formed by a locking member 26 (i.e., the preferred locking pin 22.5) in the groove 36 (i.e., the preferred lateral slot 38), such that the central portion is left open for the pressure channel 22.1.

[0120] The lower portion of the auxiliary piston 22.6 is surrounded by an annular space 22.7, which is connected to the back pressure space via an auxiliary channel 22.8.

[0121] In a drilling rig, the piston rod (working piston) has a diameter of 110 mm, and the auxiliary piston has a diameter of 60 mm. The total height of the chamber is 10 mm, and the yield distance is 8 mm. The hammer stroke is 50 mm, and the rate is set to 130 strokes / min by setting the working pressure, resulting in an average speed of 3.75 m / s at a working pressure of 50 bar. The calculated downward acceleration force with a working piston diameter of 110 mm is approximately 50 kN, of which 3 kN comes from the total weight of the hammer and its actuator (300 kg). When the 200 kg hammer strikes the drill bit, the upper part (i.e., the actuator) yields by the aforementioned 8 mm via the auxiliary piston, during which time the valve changes direction. This protects the actuator from a strong impact load. The resulting braking back pressure is mainly generated by the flow resistance in the inlet / outlet channels. The auxiliary piston also yields at top dead center, thus contributing to the stopping of the 200 kg hammer.

[0122] The outlet pipe is 350 mm long and leads to a large-diameter main supply channel inside the piston rod.

[0123] The movement of the hammer is primarily hydraulically driven by the yielding mechanism, without any impact load, because the yielding range spans the tolerances of the valve mechanism. Figure 2 The working lengths of the sliders 76 shown (especially 76a and 76b) are configured to operate within the yield range.

Claims

1. A liquid operated drilling device (1) for a borehole (100), wherein The drilling device (1) comprises a hammer (9) for forming a hole by means of a rotational and impact motion, a drill bit (24) configured to be struck by the hammer (9), a rotational device (50) for rotating the hammer (9), and a hollow drill rod (46) for connecting the rotational device (50) with the hammer (9) and for conveying pressurized liquid to the hammer (9) in order to generate the impact motion of the hammer (9) against the drill bit (24), wherein the hammer (9) comprises: A tubular body (10) having a hollow interior (12), an upper portion (10.1) and a lower portion (10.2), wherein the upper portion (10.1) receives a working fluid at a working pressure (P T ) and the lower portion is open to a back pressure (P0); and an actuator cylinder (X), wherein a piston rod (15) extends inside the main body (10) through the actuator cylinder, wherein the actuator cylinder (X) comprises: a cylinder barrel (80) comprising a top end (20') at an upper end and a bottom end (20) at a lower end in an operating position of the drilling device (1), a piston (32) having an annular surface area (B) which axially divides an annular space (ZZ) between the top and bottom ends (20', 20) into an upper and a lower space portion (42, 40) between the cylinder barrel (80) and the piston rod (15), wherein the piston rod (15) is configured to act as an impact piston (52) with a cross-sectional surface area (A) in a passage (54) through the bottom end (20) using the drill bit (24) in a lower portion (60) of the piston rod (15); wherein the piston rod (15) comprises an upper portion (22) and a lower portion (60) connected to each other; an attachment frame (85) in an upper portion of the actuator cylinder (X) which attaches the actuator cylinder (X) on the main body (10), which attachment frame (85) separates in the operating position an upper working pressure space into which the upper portion (22) of the piston rod (15) extends from a lower back pressure space to which the lower portion (60) of the piston rod delivers an impact to the drill bit; Based on a mechanical slide (76), an oscillating valve mechanism (Y) comprising valve channels to a working pressure space and a back pressure space, said valve channels alternately guiding a working pressure (P T ) and a back pressure (P0) into a second space portion (42) above the piston (32), and a channel (23, 34) formed in the piston rod (15) for conducting the working pressure P T continuously into the working pressure space portion (40) below the piston (32); characterized in that there is at least one yielding member (26) between the upper portion (22) and the lower portion (60) and a motion limiter (28) between the upper portion (22) and the lower portion (60).

2. The drilling apparatus of claim 1, wherein: The motion limiter is formed by a slot (36) and a locking member (37), wherein the slot (36) is tangential to both the upper portion (22) and the lower portion (60) and substantially transverse to the longitudinal direction of the piston rod (15).

3. The drilling apparatus of claim 2, wherein: The locking member (37) is a locking pin (22.5) arranged in the slot (36) which limits the range of motion of the upper portion (22) and the lower portion (60) relative to each other.

4. A drilling apparatus according to any one of claims 1-3, characterized in that: The yielding member (26) is a hydraulic yielding member and comprises a sealing sliding arrangement of the lower end of the piston rod in a cylindrical portion of the lower portion.

5. The drilling apparatus of claim 4, wherein: The yielding member (26) comprises a hydraulic auxiliary piston (22.6) arranged in the lower end of the upper portion (22) of the piston rod (15), wherein the diameter of the hydraulic auxiliary piston is smaller than the upper portion (22) and a working space (22.2) which receives the force of the upper portion (22).

6. The drilling apparatus of claim 5, wherein: The upper portion (22) of the piston rod (15) comprises a pressure channel (22.1) which leads from the working pressure space (45) into the working space (22.2) of the hydraulic auxiliary piston (22.6).

7. A drilling apparatus according to any one of claims 1-6, characterized in that: The surface area (B) of the piston (32), i.e. the annular surface area, is 110% to 400%, most preferably 150% to 300%, of the cross-sectional surface area (A) of the lower portion (60) of the piston rod (15).

8. A drilling apparatus according to any one of claims 1-7, characterized in that: The first valve channel (77) is formed to extend above the piston (32) and between the lower and upper space portions (40, 42), the second valve channel (33) is formed to pass through the cylinder between the second space portion (42) and the interior of the main body (10) which is open to the back pressure, the mechanical slide (76) is coaxially mounted inside the cylinder (80) for axial movement, thus always closing one valve channel (33, 77) at each end of its movement range.

9. The drilling apparatus of claim 8, wherein: The clearance of the mechanical slide (76) in the radial direction relative to the valve channels (33, 77) towards the cylinder (80) is eliminated by a single flexible seal.

10. A drilling apparatus according to any one of claims 1 to 9, wherein: The frequency of the stroke of the actuator cylinder (X) is in the range of 100-1000 strokes per minute, most preferably in the range of 120-500 strokes per minute.

11. The drilling apparatus of claim 8, wherein: The first space portion (40) for lifting the piston (32) and the second space portion (42) for impacting the piston (32) form together with the valve mechanism a reciprocating movement assembly (94) of the piston (32).

12. The drilling apparatus of claims 1-3, wherein: The yielding member (26) is an elastic element.

13. The drilling apparatus of claim 12, wherein: The material of the elastic element is one of the following: nylon, hard rubber.

14. The drilling apparatus of any one of claims 1-13, wherein: The yielding distance is 8-30%, preferably 12-20%, of the stroke length.

15. A drilling apparatus according to any one of claims 4 to 14, wherein: The diameter of the auxiliary piston (22.6) is 35-80%, preferably 40-70%, of the diameter of the piston rod (15). The diameter of the auxiliary piston (22.6) is 35-80%, preferably 40-70%, of the diameter of the piston rod (15).

Images