Baffle valve for percussion drilling tool

Abstract

This invention relates to a baffle valve for an impact drill tool. The valve includes a first side that engages with a flat surface of an element of the impact drill tool to alternately close a first fluid flow passage and a second fluid flow passage of the impact drill tool. The flat surface includes a first orifice and a second orifice, respectively in fluid communication with the first and second fluid flow passages. The first side of the baffle valve includes a first planar portion and a second planar portion, and a first curved tip portion intermediate between the first and second planar portions. The baffle valve is pivotable about the first curved tip portion between a first position and a second position, in which the first planar portion of the baffle valve is in sealing contact with the flat surface to close the first orifice, and in a second position, the second planar portion of the baffle valve is in sealing contact with the flat surface to close the second orifice.

Description

Technical Field

[0001] This invention relates to fluid-operated impact drilling tools, and more particularly to baffle valves for controlling air distribution in pneumatic drilling tools. Background Technology

[0002] Traditional downhole hammer and fluid-operated percussion drilling tools (e.g.) Figure 1 The impact drill tool shown typically includes an outer cylinder or outer wear-resistant sleeve 2, with an inner cylinder 21 mounted inside the outer cylinder or outer wear-resistant sleeve 2, which in turn engages with a rear assembly 3. A sliding reciprocating piston 1 cooperates with the inner cylinder 21 and the rear assembly 3 such that when air pressure is supplied through the rear assembly, the piston acts on the drill bit 13 with an impact effect, which is held within a chuck 22 on the outer wear-resistant sleeve.

[0003] Pressurized air is alternately supplied from the rear end 3 to the upper and lower chambers 11 and 12 to cause the piston to reciprocate. This can be achieved using a flat baffle valve 4 and an air distributor 16 having an upper surface 5 with three flat portions 6, 7, and 8, such as... Figure 1 As shown. Flat sections 7 and 8 are angled downwards relative to the central flat section 6. One side 9 of the distributor supplies air to the upper chamber 11 above the piston, and the other side 10 of the distributor assembly supplies air to the lower chamber 12 below the piston. Baffle valve 4 (in Figure 1The valve (indicated in the middle position) is arranged to pivot around the edge of the central flat portion 6 of the air distributor. When the baffle valve pivots to one side 9, it contacts the flat portion 8, thereby sealing the orifice 14 in the distributor, allowing air to pass through the orifice 15 on the other side 10 of the distributor assembly and into the channel 24 between the wear-resistant sleeve 2 and the inner cylinder 21, so as to exit below the piston, where it pressurizes the lower chamber 12, causing the piston to move upward away from the drill bit 13. At this point in the cycle, the upper chamber 11 exhausts through the piston orifice 18 and the drill bit orifice 23. As the piston moves upward, the piston orifice 18 engages with and seals the extension 17 of the air distributor, so that the upper chamber can no longer exhaust through the piston orifice. As the piston moves upward, the volume of the upper chamber 11 also decreases, thereby increasing the pressure in the upper chamber. When the piston reaches the piston nose 19 and moves away from the point of sealing engagement with the aligner 20, the lower chamber 12 begins to exhaust through the drill bit orifice 23, thereby decreasing the pressure in the lower chamber. When the pressure in the lower chamber drops below that in the upper chamber, the pressure difference causes the baffle valve 4 to reposition itself so that it contacts the flat portion 7, thereby sealing the orifice 15 in the air distributor 16. Air is then allowed to flow through the orifice 14 on the other side 9 of the distributor assembly to further pressurize the upper chamber, thereby pushing the piston downwards toward the drill bit. As the piston moves downwards, the piston nose 19 moves back into a sealing engagement with the aligner 20, preventing the lower chamber from venting through the drill bit orifice 23, and the distributor extension 17 moves out of engagement with the piston orifice 18, allowing the upper chamber to begin venting again. Thus, the volume of the lower chamber decreases, and the pressure in the lower chamber begins to increase again, restarting the cycle. Therefore, the baffle valve "oscillates" or swings back and forth around the edge of the flat portion 6, thereby alternately contacting the flat portions 7 and 8 of the distributor.

[0004] While this type of arrangement is advantageous due to its simplicity, it has several disadvantages. In particular, the damper valve will fail due to fatigue once the operating pressure exceeds the upper threshold due to the greater cyclic load on the valve. The damper valve also has a relatively short lifespan. Because the valve's oscillating motion is not smooth, the valve is subjected to relatively high stress. Therefore, it is desirable to provide a damper valve arrangement that can increase its lifespan and operate over a wider pressure range. Summary of the Invention

[0005] According to one aspect of the present invention, a baffle valve for an impact drilling tool is provided, comprising:

[0006] A first side is engageable with a flat surface of an element of an impact drill tool to alternately close a first fluid flow passage and a second fluid flow passage of the impact drill tool. The flat surface includes a first hole and a second hole that are respectively in fluid communication with the first fluid flow passage and the second fluid flow passage.

[0007] The first side of the baffle valve includes a first planar portion and a second planar portion, and a first curved tip portion between the first planar portion and the second planar portion, such that the baffle valve can pivot about the first curved tip portion between a first position and a second position. In the first position, the first planar portion of the baffle valve is in sealing contact with a flat surface to close a first orifice, and in the second position, the second planar portion of the baffle valve is in sealing contact with a flat surface of the distributor to close a second orifice.

[0008] Preferably, the first planar portion, the second planar portion, and the first curved tip portion are arranged to form a single continuous surface, with no edges, corners, or discontinuities between them. This arrangement has the advantage that the baffle valve can rotate (or rock or pivot) about the curved tip portion of the valve, thus enabling smoother operation than existing arrangements. Furthermore, this increases valve life and enhances tolerance to higher operating pressures due to reduced stress on the valve.

[0009] In one embodiment, the flat surface is the flat proximal (or rear or upper) surface of an intermediate plate disposed proximal (or rear or upper) to the fluid distributor of the impact drilling tool. In other embodiments, the flat surface may be integrally formed with the fluid distributor to form the flat proximal (or rear or upper) surface of the fluid distributor of the impact drilling tool. A baffle valve assembly may include a baffle valve and an intermediate plate and / or a fluid distributor.

[0010] The first curved tip portion of the baffle valve preferably has a radius of curvature between 10 mm and 10,000 mm. The selection of the radius of curvature of the first curved tip portion can adjust the valve's performance. For example, a larger radius of curvature of the first curved tip portion can provide improved high-power, low-frequency performance, while a smaller radius of curvature can provide improved performance at low power and high frequencies. For some applications, a radius of curvature of approximately 500 mm can be particularly advantageous.

[0011] The first curved tip portion is positioned between the first and second planar portions such that the angle between the first and second planar portions is greater than 180 degrees. When the baffle valve moves from the first or second position to the intermediate position (between the first and second positions), it moves through a stroke angle. The angle between the first and second planar portions is 180 degrees plus twice the stroke angle. Generally, a higher stroke angle results in a more responsive valve, which increases the operating frequency but reduces power. Conversely, a lower stroke angle may not provide sufficient flow area on the "open" side of the distributor to allow enough air to be supplied to the chamber, which may cause the valve to switch prematurely due to the pressure differential across the valve. Therefore, a suitable stroke angle needs to be selected so that the valve can operate effectively. Preferably, the stroke angle is between 1 and 10 degrees. Ideally, the stroke angle is approximately 3 degrees, so that when the baffle valve oscillates back and forth, it moves an angle of approximately 6 degrees.

[0012] In one embodiment, the first and second planar portions on the first side of the baffle valve are of equal length, such that the curved tip portion is positioned along the valve's centerline. The valve operates symmetrically in this embodiment.

[0013] In another embodiment, the curved tip portion is offset from the valve's centerline so that the first and second planar portions have different lengths. This offset biases the valve, causing the longer planar portion to contact the flat surface due to the increased force generated by the pressurized fluid on a larger portion (due to its larger surface area). In this embodiment, the valve is still pivotable about the curved tip portion so that the smaller planar portion contacts the flat surface, but the default position closes the larger side. The pressure difference between the upper and lower chambers of the impact drill tool (which can be connected to the first and second fluid flow passages, respectively) causes the valve to flip or swing back and forth during use. When the areas of the first and second fluid orifices are the same, a higher pressure is required to flip the valve when the larger planar portion contacts the distributor, thus biasing the larger portion closed. The position of the tip portion relative to the centerline of the baffle valve affects the degree to which the valve is biased in one direction.

[0014] In some embodiments, the second side of the baffle valve (opposite to the first side) is planar. However, in other embodiments, the second side of the baffle valve includes a third planar portion and a fourth planar portion, and a second curved tip portion between the third and fourth planar portions. Therefore, the baffle valve can be flipped so that the second side of the valve can engage with a flat surface to alternately close the first and second fluid flow passages of the impact drill tool. In this arrangement, the baffle valve is pivotable about the second curved tip portion between a third and a fourth position, in which the third planar portion of the baffle valve is in sealing contact with the flat surface to close the first orifice, and in the fourth position, the fourth planar portion of the baffle valve is in sealing contact with the flat surface to close the second orifice.

[0015] In some embodiments, the radius of curvature of the first bent tip portion is the same as the radius of curvature of the second bent tip portion. This can extend the valve's lifespan by flipping the baffle valve.

[0016] However, in other embodiments, the radius of curvature of the first bent tip portion differs from that of the second bent tip portion. This allows the different sides of the baffle valve to have different operating characteristics. As mentioned above, the radius of curvature can be used to adjust the valve's performance. Providing two different radii of curvature on the same valve allows the operator to adjust the hammer's performance by switching the baffle valve to the other side.

[0017] The first and second curved tip portions can each be located on or off the centerline of the baffle valve. One tip portion can be located on the centerline of the baffle valve while the other can be off-center, or the two tip portions can be off-center from the centerline by the same or different amounts in the same or different directions. This allows selection of the direction of valve bias and / or the degree of valve bias in one direction by choosing the appropriate side of the valve.

[0018] Preferably, the baffle valve is made of steel. In other embodiments, the valve may be made of engineering plastic material.

[0019] According to a second aspect of the invention, a baffle valve assembly is provided, comprising: a baffle valve as described above, wherein a first end and a second end of the baffle valve have convex profiles; and a baffle valve guide having at least one internal recess sized to receive the baffle valve and restrict lateral movement of the baffle valve when the valve pivots between a first position and a second position. In an embodiment, the baffle valve guide includes a pair of internal recesses, each internal recess sized to receive one end of the baffle valve. Preferably, each internal recess includes an angled inner surface configured to engage with the convex end of the baffle valve to restrict lateral movement of the baffle valve.

[0020] The advantage of the baffle valve guide is that it minimizes the lateral movement of the baffle valve when the baffle valve pivots from the first position to the second position.

[0021] According to another aspect of the invention, a downhole hammer is provided, comprising: an outer cylindrical outer wear-resistant sleeve; a sliding piston mounted to reciprocate within the outer wear-resistant sleeve to impact a drill bit of a drill bit assembly located at the front end of the outer wear-resistant sleeve; and a baffle valve or baffle valve assembly as described above, the baffle valve or baffle valve assembly being configured to control airflow to cause the piston to reciprocate. Attached Figure Description

[0022] Figure 1 It is a longitudinal section view of an impact drilling tool including a conventional baffle valve device;

[0023] Figure 2 This is a perspective view of the baffle valve according to the present invention;

[0024] Figure 3 This is a side view of a baffle valve according to a first embodiment of the present invention, showing its use with the intermediate plate of an impact drill tool;

[0025] Figure 4 yes Figure 3 A top-view perspective view of the device;

[0026] Figure 5 yes Figure 3 A side view of the device, showing the baffle valve in the first position;

[0027] Figure 6A This is a side view of a baffle valve according to a second embodiment of the present invention;

[0028] Figure 6B yes Figure 6A Top view of the baffle valve;

[0029] Figure 7 This is a side view of a baffle valve according to a third embodiment of the present invention;

[0030] Figure 8 This is a cross-sectional view of a baffle valve assembly according to a second aspect of the present invention; and

[0031] Figure 9 This is a longitudinal sectional view of a downhole hammer including the baffle valve assembly according to the present invention. Detailed Implementation

[0032] Figure 2 The diagram illustrates a baffle valve 100 according to a first embodiment of the present invention. The valve includes a first side 101 that can engage with a flat surface 102 of a middle base plate 103 of an impact drill tool, such as... Figure 3 and4 As shown, this is to alternately close the first fluid flow passage and the second fluid flow passage of the impact drill tool. The flat surface 102 includes a first hole 104 and a second hole 105 that are in fluid communication with the first fluid flow passage and the second fluid flow passage, respectively.

[0033] The first side 101 of the baffle valve 100 includes a first planar portion 106, a second planar portion 107, and a first curved tip portion 108 located between the first and second planar portions. As shown, the first planar portion, the second planar portion, and the first curved tip portion form a single continuous surface without edges, corners, or discontinuities between them. The first planar portion 106 and the second planar portion 107 of the first side 101 of the baffle valve are of equal length, such that the curved tip portion 108 is positioned along the valve's centerline 109. Therefore, the valve operation in this embodiment is symmetrical.

[0034] Figure 5 The diagram shows a baffle valve 100 in a first position, wherein a first planar portion 106 of the baffle valve is in sealing contact with a flat surface 102 to close a first orifice 104. The valve is pivotable about a first curved tip portion 108 from the first position to a second position, in which a second planar portion 107 of the baffle valve is in sealing contact with the flat surface 102 to close a second orifice 105.

[0035] exist Figures 2 to 5 In the illustrated embodiment, the baffle valve has a tip radius of 500 mm. In other embodiments, the radius of curvature of the first curved tip portion can be between 10 mm and 10,000 mm.

[0036] exist Figures 2 to 5 In the illustrated embodiment, the angle between the first planar portion and the second planar portion is approximately 186 degrees. When the baffle valve 100... Figure 5 The first position shown moves to Figure 3 When it reaches the middle position shown, it moves through approximately a three-degree stroke angle. Therefore, when the baffle valve completes its swing and returns, it has moved approximately a six-degree angle.

[0037] exist Figure 6A and 6B The diagram illustrates a baffle valve 200 according to another embodiment of the present invention. In this embodiment, the first curved tip portion 208 is offset from the centerline of the valve, such that the first planar portion 206 and the second planar portion 207 have different lengths L1 and L2, as shown below. Figure 6AAs shown. A bias valve is used such that the larger planar portion 206 of the valve contacts the flat surface due to the increased force generated by the fluid pressure of the booster fluid supplied by the rear assembly (indicated by the arrow). In this embodiment, the valve can still pivot about the curved tip portion 208 so that the smaller planar portion of the valve contacts the flat surface, but the default position will be such that the larger portion is closed.

[0038] Figure 7 The diagram illustrates a baffle valve 300 according to a third embodiment of the present invention. The baffle valve 300 includes a first side 301, which includes a first planar portion 306 and a second planar portion 307 connected by a first curved tip portion 308. The baffle valve also includes a second side 310 opposite to the first side 301. The second side 310 includes a third planar portion 311 and a fourth planar portion 312, and a second curved tip portion 313 intermediate between the third and fourth planar portions. Therefore, the baffle valve 310 can be flipped so that the second side of the valve can engage with the flat surface 102 to alternately close the first and second fluid flow passages of the impact drill tool.

[0039] exist Figure 7 In the illustrated embodiment, the radius of curvature of the first bent tip portion 308 is the same as the radius of curvature of the second bent tip portion 313. This allows for an extension of valve life by flipping the baffle valve. In an alternative embodiment, the radius of curvature of the first bent tip portion 308 may be different from the radius of curvature of the second bent end portion 313. Providing two different radii of curvature on the same valve allows the operator to adjust the hammer's performance by switching the baffle valve to the other side.

[0040] exist Figure 7 In the illustrated embodiment, the first curved tip portion 308 is located on the centerline of the baffle valve, and the second curved tip portion 313 is offset from this centerline. This allows the degree of valve bias in one direction to be selected by choosing the appropriate side of the valve. In an alternative embodiment, both tip portions may be located on the centerline of the baffle valve, or each tip portion may be offset from the centerline by the same or different amounts.

[0041] Figure 8 The diagram illustrates a baffle valve assembly according to an embodiment of the present invention. Assembly 820 includes components similar to those referenced above. Figures 2 to 5The similar baffle valve 800 has a first side 801, which includes a first planar portion 806, a second planar portion 807, and a first curved tip portion 808. In this embodiment, each end 821, 822 of the baffle valve has a convex profile. The assembly also includes a baffle valve guide 823 having a pair of internal recesses 824, each internal recess 824 being sized to receive one end of the baffle valve 800. Each internal recess includes angled inner surfaces 825, 826 at its end, which are configured to mate with the convex ends 821, 822 of the baffle valve to restrict lateral movement of the baffle valve when the valve pivots between a first position and a second position.

[0042] Figure 9 This illustrates a downhole hammer including a baffle valve assembly 920 according to an embodiment of the invention. The tool 900 includes a piston 1 mounted for reciprocating motion within an outer wear-resistant sleeve 2. When air is supplied through a rear end assembly 3, the piston acts with an impact effect on the drill bit 13 at the front end of the wear-resistant sleeve.

[0043] Pressurized air is alternately supplied from the rear end 3 to the upper chamber 11 and the lower chamber 12 to cause the piston to reciprocate. This is achieved using a baffle valve assembly 920, which includes a baffle valve 900 having a first side 901 that engages with a flat surface 902 of an intermediate base plate 903 to alternately close a first fluid flow passage 17 and a second fluid flow passage 18 of the impact drill tool. The flat surface 902 includes a first hole 904 and a second hole 905 that are in fluid communication with the first and second fluid flow passages, respectively. The first side 901 of the baffle valve 900 includes a first planar portion 906 and a second planar portion 907, and a first curved tip portion 908 located between the first and second planar portions. As shown, the first planar portion, the second planar portion, and the first curved tip portion form a single continuous surface without intermediate edges, corners, or discontinuities. The first planar portion 906 and the second planar portion 907 of the first side 901 of the baffle valve 900 are of equal length, such that the curved tip portion 908 is positioned along the centerline of the valve and the hammer. The valve 900 is pivotable about the first curved tip portion 908 between a first position and a second position, in which the first planar portion 906 of the baffle valve is in sealing contact with the flat surface 902 to close the first orifice 904, and in the second position, the second planar portion 907 of the baffle valve is in sealing contact with the flat surface 902 to close the second orifice 905.

[0044] Each end 921, 922 of the baffle valve has a convex profile. Assembly 920 also includes a baffle valve guide 923 having a pair of internal recesses 924 sized to receive the baffle valve 900. Each internal recess includes angled inner surfaces 925, 926 at its end, which are configured to mate with the convex ends 921, 922 of the baffle valve to restrict lateral movement of the baffle valve when it pivots between a first position and a second position.

[0045] An intermediate substrate 903 is disposed above the air distributor 16. In other embodiments, the substrate 903 may be integrally formed with the air distributor 16. One side 9 of the air distributor supplies air to the upper chamber 11 above the piston, and the other side 10 of the distributor supplies air to the lower chamber 12 below the piston. Figure 9 The baffle valve 900, positioned in the middle, is arranged to pivot about its first curved tip portion 908, as described above. When the baffle valve pivots to one side 9, the first flat portion 906 of the baffle valve seals against the flat surface 902 to close the first orifice 904, allowing air to pass through the orifice 905 in the other side 10 of the substrate and into a channel within the wall of the wear-resistant sleeve 2 to exit below the piston, where it pressurizes the lower chamber 12, causing the piston to move upward away from the drill bit 13. The upper chamber 11 is opened through a flow passage 927 for venting. As the piston moves upward, the flow passage 928 opens to allow venting from the lower chamber. Simultaneously, the flow passage 927 for venting from the upper chamber 11 is sealed by the piston, thus the pressure in the upper chamber increases as the volume of the upper chamber decreases. When the pressure in the lower chamber drops below the pressure in the upper chamber, the pressure difference causes the baffle valve 903 to switch positions so that the second flat portion 907 makes sealing contact with the flat surface 902, thereby sealing the hole 905 in the substrate 903. Air can then flow through the hole 904 in the other side 9 of the substrate and through the air distributor to further pressurize the upper chamber, thereby pushing the piston downwards toward the drill bit. As the piston moves downwards, the pressure in the top chamber decreases, and the pressure in the lower chamber begins to increase again, thus restarting the cycle. Therefore, the baffle valve smoothly oscillates back and forth continuously around the first curved tip portion 908, causing the first flat portion 906 and the second flat portion 907 to alternately contact the substrate 903. The lateral movement of the baffle valve 900 is limited by the guide 923.

[0046] When used herein with reference to the present invention, the terms “comprising / including” and “having / including” are used to specify the presence of the said feature, integer, step, or component, but do not exclude the presence or addition of one or more other features, integers, steps, components, or groups thereof.

[0047] It should be understood that, for clarity, certain features of the invention described in a single embodiment may also be provided in combination in a single embodiment. Conversely, for simplicity, various features of the invention described in a single embodiment may also be provided individually or in any suitable sub-combination.

Claims

1. A baffle valve for an impact drilling tool, comprising: A first side, which can engage with a flat surface of an element of an impact drill tool, to alternately close a first fluid flow passage and a second fluid flow passage of the impact drill tool, the flat surface including a first hole and a second hole respectively in fluid communication with the first fluid flow passage and the second fluid flow passage. The first side of the baffle valve includes a first flat portion, a second flat portion, and a first curved tip portion. The first curved tip portion is located between the first flat portion and the second flat portion, allowing the baffle valve to pivot about the first curved tip portion between a first position and a second position. In the first position, the first flat portion of the baffle valve is in sealing contact with the flat surface to close the first orifice. In the second position, the second flat portion of the baffle valve is in sealing contact with the flat surface to close the second orifice.

2. The baffle valve according to claim 1, wherein: The first curved tip portion is exactly between the first planar portion and the second planar portion.

3. The baffle valve according to claim 1 or 2, wherein: The first planar portion, the second planar portion, and the first curved tip portion are configured to form a single continuous surface.

4. The baffle valve according to claim 3, wherein: The single continuous surface is configured such that no edges, corners, or discontinuities are formed between the first planar portion, the second planar portion, and the first curved tip portion.

5. The baffle valve according to claim 1 or 2, wherein: The radius of curvature of the first curved tip portion is in the range of 10 mm to 10,000 mm.

6. The baffle valve according to claim 1 or 2, wherein: The lengths of the first planar portion and the second planar portion on the first side of the baffle valve are equal, such that the first curved tip portion is positioned along the centerline of the baffle valve.

7. The baffle valve according to claim 1 or 2, wherein: The first curved tip portion deviates from the centerline of the baffle valve, causing the first planar portion and the second planar portion to have different lengths.

8. The baffle valve according to claim 1, wherein: The baffle valve includes a second side opposite to the first side. The second side of the baffle valve includes a third planar portion and a fourth planar portion, and a second curved tip portion between the third planar portion and the fourth planar portion. The baffle valve is flip-up so that a second side of the baffle valve can engage with the flat surface to alternately close the first and second fluid flow passages of the impact drill tool.

9. The baffle valve according to claim 8, wherein: The radius of curvature of the first curved tip portion is the same as the radius of curvature of the second curved tip portion.

10. The baffle valve according to claim 8, wherein: The radius of curvature of the first curved tip portion is different from that of the second curved tip portion.

11. The baffle valve according to any one of claims 8 to 10, wherein: The first and second curved tip portions are each located on the center line of the baffle valve.

12. The baffle valve according to any one of claims 8 to 10, wherein: At least one of the first curved tip portion and the second curved tip portion deviates from the centerline of the baffle valve.

13. The baffle valve according to claim 12, wherein: The first and second curved tip portions deviate from the centerline of the baffle valve by different amounts.

14. A baffle valve assembly, the baffle valve assembly comprising: The baffle valve according to any one of claims 1 to 7, wherein the first end and the second end of the baffle valve have a convex profile; and A baffle valve guide having at least one internal recess sized to receive a baffle valve and restrict lateral movement of the baffle valve when the baffle valve pivots between a first position and a second position.

15. The baffle valve assembly according to claim 14, wherein: The baffle valve guide includes a pair of internal recesses, each sized to receive one end of the baffle valve.

16. A downhole hammer, the downhole hammer comprising: Outer cylindrical wear-resistant sleeve; slide A piston, the sliding piston being mounted to reciprocate within an outer wear-resistant sleeve to impact a drill bit of a drill bit assembly located at the front end of the outer wear-resistant sleeve; and a baffle valve according to any one of claims 1 to 13, the baffle valve being configured to control airflow to cause the sliding piston to reciprocate.

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