Sleeve element and a rock drilling machine comprising such a sleeve element

Abstract

The disclosure relates to a sleeve element (10) and a hydraulic rock drilling machine comprising such a sleeve element. The sleeve element (10) is configured to be arranged around a cylindrical element (20) in a cylindrical space (26) inside a housing (2) of the rock drilling machine. The sleeve element (10) comprises one or more conduits (11), configured to convey hydraulic fluid between a fluid line in the housing of the rock drilling machine and a chamber (12) formed between the sleeve element and the cylindrical element (20). A recess (13) is provided in the outer surface (23) of the sleeve element (10) for conveying pressurised hydraulic fluid trapped between the sleeve element (10) and the housing (2), the recess (13) being arranged in communication with a drain outlet line (22) in communication with the cylindrical space (26).

Description

[0001] SLEEVE ELEMENT AND A ROCK DRILLING MACHINE COMPRISING SUCH A

[0002] SLEEVE ELEMENT

[0003] TECHNICAL FIELD

[0004] The present disclosure relates to a sleeve element for a rock drilling machine and a rock drilling machine comprising such a sleeve element. Specifically, the present disclosure relates to a sleeve element of a tubular shape configured to be arranged around a cylindrical element in a cylindrical space inside a housing of the rock drilling machine.

[0005] BACKGROUND

[0006] In the technical field of percussive rock drilling the percussion is conventionally achieved by a hydraulic arrangement where a piston is arranged in a rock drilling cylinder.

[0007] The piston is arranged to provide a percussive action to a shank adapter, which is connected to a drill rod of a drill string carrying a drill bit. The rock drilling machine and specifically the rock drilling cylinder needs to be configured to withstand the pulsating pressures that are provided to put the piston in motion. In addition to the immediate forces from the pulsating pressures the fatigue stress from them could also damage the housing.

[0008] In order to minimise wear on the housing it is conventional to provide a metal liner, in the form of sleeve element, between the moving piston and the housing. The relatively cheap sleeve element can be replaced if damaged and it can also be configured with material properties for a good sliding contact between the piston and the sleeve element in a manner that would not be possible if the piston were arranged directly in the housing. A sleeve element may also be beneficial from a flow distribution point of view.

[0009] Today’s typical design of a rock drilling cylinder includes a sleeve element and a housing where different active pressures inside the rock drilling cylinder are separated with radial soft seals such as O-rings between the sleeve element and the housing. As an alternative to the soft seals the existing small gap between the sleeve element and the housing may be made tight enough to achieve a sealing effect.

[0010] The flow in a gap is proportional to the gap height to the power of 3, such that a tight gap can be very limiting with respect to the flow. However, it will not be limiting with respect to the pressure. Instead, even in a very tight gap the pressure between the sleeve element and the housing can be very high. Also, with a conventional sleeve element, the volume of the pressurized hydraulic fluid will be greater than if no sleeve element were used. The greater volume in combination with the high pressures will in turn imply higher forces on the housing, which may lead to fatigue failure on the housing.

[0011] In order to withstand such high forces, it is conventional to use a forged housing as opposed to a casted housing. Forged housing parts are more expensive to produce than cast products, and in addition, forging is less adapted to the complex geometry of the housing of the rock drilling cylinder.

[0012] It would be advantageous to find a solution of a rock drilling machine overcoming, or at least alleviating, at least one or some of the drawbacks of the prior art.

[0013] SUMMARY

[0014] It is an object of the present disclosure to provide a percussion rock drilling machine, which is well adapted to withstand the pulsating pressures provided during operation of the rock drilling machine and which is configured to withstand the fatigue stress provided over time. Specifically, an object is to provide a solution that enables the use of casted housing for the rock drilling cylinder of the rock drilling machine.

[0015] The above and further objects are solved by the subject matter of the appended independent claims. Further advantageous embodiments can be found in the dependent claims.

[0016] According to a first aspect, the disclosure relates to a sleeve element in a hydraulic rock drilling machine, the sleeve element having a tubular shape and being configured to be arranged around a cylindrical element in a cylindrical space inside a housing of the rock drilling machine.

[0017] The housing of the rock drilling machine typically comprises one or more fluid lines and a drain outlet line opening into the cylindrical space.

[0018] The sleeve element comprises one or more conduits, configured to convey hydraulic fluid between the fluid line in the housing of the rock drilling machine and a chamber formed between the sleeve element and the cylindrical element.

[0019] A first recess is provided in an outer surface of the sleeve element for draining occurring pressurised hydraulic fluid trapped in a gap between the sleeve element and the housing to a drain position located opposite the drain outlet line. As a consequence of the first recess, the pressure acting on the housing of the rock drill surrounding the sleeve will be reduced to almost nothing except for a very limited area around the conduit through the sleeve. Thereby, the forces acting on the housing will also be very limited, and in particular they will be limited to a small area around the conduit which will effectively reduce fatigue on the housing parts, especially in view of that the area surrounding the fluid line needs to be configured to withstand the pressure from the fluid passing through it already as it is.

[0020] In embodiments, the first recess is formed as a track along the outer surface of the sleeve element leading to the drain position for draining hydraulic fluid from the cylindrical space.

[0021] The track shaped recess may be configured to effectively convey pressurised hydraulic fluid to the drain position.

[0022] In embodiments, the first recess extends in an axial direction along the outer surface of the sleeve element.

[0023] This allows for the drain outlet line opening to be positioned axially spaced from the fluid line(s).

[0024] In embodiments, a second recess is arranged in the outer surface around the conduit, said second recess being connected to the first recess to convey occurring fluid from the second recess, via the first recess to the drain outlet line.

[0025] The second recess is arranged to capture pressurised hydraulic fluid from close to the fluid line opening to restrict the area that will we exposed to an elevated pressure.

[0026] In embodiments, said second recess fully encloses the conduit to effectively limit the area that will we exposed to an elevated pressure, and in embodiments, said second recess is ring-shaped.

[0027] In embodiments, a third recess is formed at the drain position, the third recess being formed as a circumferential track radially around the outer surface of the sleeve element and being connected to the first recess.

[0028] The circumferential orientation of the third drain recess allows for a connection to the opening to the drain outlet line irrespective of radial position thereof. In embodiments, a first and a second sealing are arranged around a first and a second axial end of the sleeve, respectively, the drain position being positioned on the outer surface of the sleeve element adjacent one of the first and a second sealings.

[0029] As an alternative, a sleeve arrangement may be provided, which comprises a first separate sealing unit and a second separate sealing unit, which are arranged to be positioned adjacent the first and a second axial ends of the sleeve, respectively. The sealing elements may be totally separated from the sleeve element to facilitate replacement of them, when needed, for instance when their sealing function appears to have been decreased.

[0030] In embodiments, the sleeve element comprises a rotation inhibiting element in the form of a recess or protrusion configured to interact with a complementary rotation inhibiting element of the housing.

[0031] This mutual rotation inhibiting elements are useful to align the opening with the fluid line(s) and the drain outlet line.

[0032] In embodiments, the sleeve element is configured to be provided in a cylindrical space in a rock drill cylinder of the rock drilling machine outside a cylindrical element in the form of a piston for providing a percussive hydraulic pressure to a shank adapter that is configured to be connected to a drill rod during drilling operation.

[0033] In embodiments, the sleeve element is configured to be provided in a cylindrical space in a valve housing of the rock drilling machine outside a cylindrical element in the form of a valve slide for controlling a hydraulic fluid in the rock drilling machine.

[0034] In embodiments, the sleeve element is made of metal. It may also be made from a ceramic, a composite or possibly a high-density plastic material.

[0035] According to a second aspect, the disclosure relates to a housing enclosing a cylindrical space, the housing comprising a fluid line and a drain outlet line leading into and out from, respectively, the cylindrical space, the housing forming part of a rock drilling machine and being configured to house a sleeve element as described above. The fluid line is arranged to open into a conduit of the one or more conduits of the sleeve element and the drain outlet line is arranged to open to the drain position.

[0036] According to a third aspect, the disclosure relates to a rock drilling machine comprising a housing enclosing a cylindrical space, the housing comprising a fluid line and a drain outlet line, wherein the rock drilling machine further comprises a piston arranged in a rock drill cylinder of the rock drilling machine for providing a percussive hydraulic pressure to a shank adapter that is configured to be connected to a drill rod during operation.

[0037] The rock drilling machine comprises at least one sleeve element in accordance with any one of the preceding claims provided around the piston.

[0038] In embodiments, the rock drilling machine comprises a valve slide for controlling the hydraulic fluid provided to the rock drill cylinder.

[0039] Further, the rock drilling machine according to this embodiment comprises at least one sleeve element as described above provided around the valve slide.

[0040] In embodiments, the drain outlet line is arranged at an axial end of the cylindrical space of the housing.

[0041] In embodiments, the rock drill cylinder of the rock drilling machine is made of a casted metal or alloy.

[0042] The use of a casted rock drill cylinder is made possible by the pressure relief provided by the current disclosure. Casting is beneficial in that is cost efficient and allows for complex geometries of the rock drill cylinder to be achieved.

[0043] Other embodiments of the disclosure according to the three aspects and advantages thereof will be apparent from the detailed description and the appended drawings.

[0044] BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Below, specific embodiments of the disclosure will be described with reference to the appended drawings, of which:

[0046] Fig. 1 is a very schematic view of a rock drilling machine according to possible embodiment of the disclosure,

[0047] Fig. 2 is a schematic view of a rock drill cylinder of a rock drilling machine,

[0048] Fig. 3 is an exploded view of the rock drill cylinder in Fig. 2,

[0049] Fig. 4 is an exploded view of a cylindrical element, a sleeve element and a housing,

[0050] Fig. 5 is a top view of a housing comprising a cylindrical element and a sleeve element, Fig. 6 is a sectional view of a cylindrical element, a sleeve element and a housing taken along the line VI-VI in Fig. 5,

[0051] Fig. 7 is a longitudinal sectional view of a housing comprising a cylindrical element and a sleeve element according to a second embodiment.

[0052] Fig. 8 is a cross-sectional view of a cylindrical element, a sleeve element and a housing taken along the line VIII-VIII in Fig. 7,

[0053] Fig. 9 is top view of a conduit in a sleeve element, and

[0054] Fig. 10 illustrates the pressure profile around the conduit in Fig. 9 in a sectional view taken along the line X-X in Fig. 9.

[0055] DETAILED DESCRIPTION

[0056] In Fig. 1 , a hydraulic rock drilling machine 1 according to an exemplary embodiment of the disclosure is illustrated in a very schematic manner.

[0057] The rock drilling machine 1 may be said to be comprised of three main parts arranged inside a housing portion 2 of the rock drilling machine 1 , from the right in the drawing:

[0058] • A percussion unit comprising a drill piston 6 for providing a percussive motion to a drill string by repeated hammering on a shank adapter 3, which is configured to be connected to such a drill string. The drill piston 6 is arranged in a rock drill cylinder 7, which may form an integrated housing part of the housing portion 2 of the rock drilling machine 1.

[0059] • A damper unit, comprising a damper 4 arranged to dampen the recoil effect from the drill string during drilling, and

[0060] • An extractor unit comprising an extractor 5 arranged to assist when the drill string is retracted from the drill hole by affecting the shank adapter 3, after a completed drilling operation or when the drill string has become stuck inside a drill hole.

[0061] The function of these details is well known to a person skilled in the art and will not be described in detail except for details concerning the embodiments of the disclosure.

[0062] Fig. 2 is perspective view of a rock drill cylinder 7, and Fig. 3 is a partly exploded view of the same rock drill cylinder 7. The rock drill cylinder 7 houses the drill piston 6 and a valve slide 8 for controlling the pulsating pressure to the drill piston 6. The valve slide 8 is arranged inside a valve housing 9 that forms part of the housing portion 2 of the rock drill cylinder 7. The valve slide 8 is not visible in the drawings but reference “8” has been added in Fig. 3 to illustrate a possible position of the housing 2 inside which the valve slide may be positioned. The valve slide is arranged to control the hydraulic fluid to and from a piston chamber.

[0063] In accordance with the present disclosure the drill piston 6 is arranged in a sleeve element 10 and the valve slide 8 is arranged in another sleeve element (not shown).

[0064] These sleeve elements are used to minimise wear on the moving piston or valve slide, respectively, and on the housing portions surrounding them.

[0065] Exemplary embodiments of a sleeve element 10 in accordance with the disclosure is illustrated in Figs. 4 - 8.

[0066] As is best illustrated in the exploded view in Fig. 4, the sleeve element 10 has a tubular shape configured to be arranged around a cylindrical element 20 in a cylindrical space 26 inside a housing portion 2 of the rock drilling machine 1.

[0067] In this context the terms “tubular” and “cylindrical” indicates that the shape is mainly tubular and cylindrical, respectively but that minor portions of the shapes may differ from the main shape, e.g. for functional reasons.

[0068] As is suggested in Fig. 2 and 3, the cylindrical element 20 may be any element that is actuatable by means of a hydraulic fluid, such as a drill piston 6, or it may may be an element arranged to control a hydraulic flow such as a valve slide 8.

[0069] The sleeve element 10 illustrated in Figs. 4 and 6 comprises a conduit 11 , configured to convey hydraulic fluid between a fluid line 24 in the housing portion 2 of the rock drilling machine 1 and a chamber 12 formed inside the sleeve element 10.

[0070] In the shown embodiment, the cylindrical element 20 is a piston that may be pushed outwards to the left in Fig. 6, by providing pressurised hydraulic fluid through the fluid line 24 and the conduit 11 of the sleeve element 10 into the chamber 12. This is a simplified construction intended to illustrate the functionality of the sleeve 10, which is a main feature of this disclosure.

[0071] Typically, the sleeve element 10 may be used in a double acting hydraulic cylinder with two opposed chambers arranged to push the cylindrical element 20 in opposite directions. In such a construction at least two fluid lines 24 need to be arranged and the sleeve would have at least two conduits 11 , one for each fluid line 24, configured to convey hydraulic fluid between the fluid lines 24 and the respective chambers inside the sleeve element 10.

[0072] As is best visible in Fig. 4, a first drain recess 13 is provided in the outer surface 23 of the sleeve element 10. The first drain recess 13 is arranged to drain away pressurised hydraulic fluid trapped in a gap 25 (shown in Fig. 6) between the sleeve element 10 and the inside of the housing portion 2, the first drain recess 13 being configured to be in communication with a drain outlet line 22 opening into the generally cylindrical space 26. The first drain recess 13 extends in an axial direction of the sleeve element 10.

[0073] In addition to this first drain recess 13, a second drain recess 14 may be arranged on the outer surface of the sleeve element 10, enclosing the conduit 11 , said second drain recess 14 being connected to the first drain recess 13 for conveying occurring fluid from the second drain recess 14 to a drain position PD in the cylindrical space 26, opposite the drain outlet line 22. The second drain recess 14 may be ring-shaped so as to enclose the conduit 11 with a uniform distance from the edge of the conduit 11 .

[0074] Also visible in Fig. 4 is a third drain recess 29, which is provided at the drain position PD as a circumferential track running radially around the outer surface 23 of the sleeve 10 element and being connected to the first recess 13.

[0075] The idea of the first drain recess 13 and the second drain recess 14 is to relieve the pressure between sleeve element 10 and the surrounding housing portion 2. This is illustrated in Figs. 9 and 10, where Fig. 10 is sectional view taken along the line X-X in Fig. 9.

[0076] In Fig. 10 a pressure profile PP in the gap 25 between the sleeve element 10 and the surrounding housing portion 2 is illustrated over the geometry at and around the conduit 11 . At the conduit 11 a working pressure provided from the fluid line 24 is prevailing, while in the first drain recess 13 and the thereto connected second drain recess 14 the pressure is at a minimum as the first drain recess 13 stands in communication with the drain outlet line 22, which preferably is leading to tank.

[0077] As is apparent from the pressure profile PP there will be no raised pressure levels in the gap 25 outside of the immediate area around the conduit 11 . Of course, the pressure drop from the conduit 11 to the second drain recess 14 will give rise to a certain efficiency loss. However, if the gap 25 may be made sufficiently tight this loss will be close to negligible. The relatively low pressure acting on the housing portion 2 of the rock drill 1 surrounding the sleeve element 10 will of course relieve the housing from the high pressures that are normal when a sleeve element is used. Thereby, the rock drill cylinder 7 may be made of a less expensive material, such as casted metal, metal alloy or a ceramic.

[0078] In the shown embodiments the drain outlet line 22 is arranged at a first axial end 27 of the cylindrical space 26 of the housing portion 2.

[0079] A first and a second sealing 15, 16 are arranged around a first and a second axial end 17, 18 of the sleeve 10, respectively. The first drain recess 13 is provided between the first and the second sealings 15, 16, as is the drain outlet line 22, which in the shown embodiment is arranged close to the first sealing 15, at the first end 17 of the sleeve element 10.

[0080] In Figs. 7 and 8 a sleeve arrangement according to a second embodiment is shown. This arrangement is similar to the arrangement illustrated in Figs. 5 and 6 but differ in two major ways. Firstly, instead of sealings that are arranged around the sleeve element, separate sealing elements 30 and 31 are arranged on opposite sides of the sleeve element 10.

[0081] Further, in order to align the conduit 11 with the drain outlet line 22, the sleeve element 10 may be provided with a rotation inhibiting element 19 in the form of a recess or protrusion configured to interact with a complementary rotation inhibiting element 21 of the housing portion 2. In the shown embodiment the rotation inhibiting element 19 of the sleeve element 10 is a recess and the complementary rotation inhibiting element 21 of the housing portion 2 is a protrusion, but it may also be vice versa. Also, the protrusion may be a separate part to be positioned in two recesses, one in the sleeve element 10 and one in the housing portion 2.

[0082] As is illustrated in Fig 2 and 3, the sleeve element may be configured to be provided in a generally cylindrical space 26 in a rock drill cylinder 7 of the rock drilling machine 1 outside a cylindrical element in the form of a drill piston 6 arranged for providing a percussive hydraulic pressure to a shank adapter 3 that is configured to be connected to a drill rod during drilling operation.

[0083] Also, the sleeve element 10 may be configured to be provided in another generally cylindrical space in a valve housing 9 of the rock drilling machine 1 , outside a cylindrical element in the form of a valve slide 8. Such a valve slide 8 is arranged to control a hydraulic fluid in the rock drilling machine 1 , specifically the percussive hydraulic pressure provided to the drill piston 6. The sleeve element is preferably made of metal, a metal alloy or a ceramic.

[0084] The rock drilling machine 1 may comprises at least one sleeve element, but preferably it comprises two sleeve elements.

[0085] Above, the disclosure has been described with reference to specific embodiments. The disclosure is however not limited to these embodiments. It is obvious to a person skilled in the art that other embodiments are possible within the scope of the following claims.

Claims

CLAIMS1. A sleeve element (10) in a hydraulic rock drilling machine (1), the sleeve element (10) having a tubular shape and being configured to be arranged around a cylindrical element (20) in a cylindrical space (26) inside a housing (2) of the rock drilling machine (1), wherein the sleeve element (10) comprises one or more conduits (11), configured to convey hydraulic fluid to a chamber (12) formed inside the sleeve element (10), and wherein a first recess (13) is provided in an outer surface (23) of the sleeve element (10) for draining occurring pressurised hydraulic fluid trapped in a gap (25) between the sleeve element (10) and the housing (2) to a drain position (PD).

2. The sleeve element (10) according to claim 1, wherein the first recess (13) is formed as a track along the outer surface (23) of the sleeve element (10) leading to the drain position (PD) for draining hydraulic fluid from the cylindrical space (26).

3. The sleeve element (10) according to claim 1 or 2, wherein the first recess (13) extends in an axial direction along the outer surface of the sleeve element.

4. The sleeve element (10) according to claim 1, 2 or 3, wherein a second recess (14) is arranged in the outer surface (23) around the conduit (11), said second recess (14) being connected to the first recess (13) to convey occurring fluid from the second recess (14), via the first recess (13) to the drain outlet line (22).

5. The sleeve element (10) according to claim 4, wherein said second recess (14) fully encloses the conduit (11).

6. The sleeve element (10) according to claim 5, wherein said second recess (14) is ring-shaped.

7. The sleeve element (10) according to any one of the preceding claims, wherein a third recess (29) is formed at the drain position (PD), the third recess (29) being formed as a circumferential track radially around the outer surface (23) of the sleeve element (10) and being connected to the first recess (13).

8. The sleeve element (10) according to any one of the preceding claims, wherein a first sealing (15) and a second sealing (16) are arranged around a first and a second axialend (17, 18) of the sleeve (10), respectively, the drain position (PD) being positioned on the outer surface (23) of the sleeve element (10) adjacent one of the first and second sealings (15, 16).

9. The sleeve element (10) according to any one of the preceding claims, wherein the sleeve element (10) comprises a rotation inhibiting element (19) in the form of a recess or protrusion configured to interact with a complementary rotation inhibiting element (21) of the housing (2).

10. The sleeve element (10) according to any one of the preceding claims, wherein the sleeve element (10) is configured to be provided in a cylindrical space (26) in a rock drill cylinder (7) of the rock drilling machine (1) outside a cylindrical element (20) in the form of a piston (6) for providing a percussive hydraulic pressure to a shank adapter (3) that is configured to be connected to a drill rod during drilling operation.

11. The sleeve element (10) according to any one of the claims 1 - 9, wherein the sleeve element (10) is configured to be provided in a cylindrical space (26) in a valve housing (9) of the rock drilling machine (1) outside a cylindrical element (20) in the form of a valve slide (8) for controlling a hydraulic fluid in the rock drilling machine (1).

12. The sleeve element (10) according to any one of the preceding claims, wherein the sleeve element (10) is made of metal.

13. A sleeve arrangement, comprising the sleeve element (10) according to any one of the claims 1 - 7 or 9 - 12 when not dependent on claim 8, the sleeve arrangement further comprising a first separate sealing unit (30) and a second separate sealing unit (31), which are arranged to be positioned adjacent a first and a second axial end (17, 18) of the sleeve (10), respectively.

14. A housing (2) enclosing a cylindrical space (26), the housing (2) comprising a fluid line (24) and a drain outlet line (22) leading in to and out from, respectively, the cylindrical space (26), the housing (2) forming part of rock drilling machine (1) and being configured to house a sleeve element (10) according to any one of the claims 1 - 12 or a sleeve arrangement according to claim 13, the fluid line (24) being arranged to open into a conduit of the one or more conduits (11) of the sleeve element (10) and the drain outlet line (22) being arranged to open into the drain position (PD).

15. A rock drilling machine (1) comprising a housing (2) enclosing a cylindrical space (26), the housing (2) comprising a fluid line (24) and a drain outlet line (22), wherein the rock drilling machine (1) further comprises a piston (6) arranged in a rock drill cylinder (7) of the rock drilling machine (1) for providing a percussive hydraulic pressure to a shank adapter (3) that is configured to be connected to a drill rod during operation, wherein the rock drilling machine (1) comprises at least one sleeve element (10) in accordance with any one of the claims 1 - 12 or a sleeve arrangement according to claim 13, of which the sleeve element (10) is provided around the piston (6) inside the cylindrical space (26).

16. A rock drilling machine (1) comprising a housing (2) enclosing a cylindrical space (26), the housing (2) comprising a fluid line (24) and a drain outlet line (22), wherein the rock drilling machine (1) further comprises a valve slide (8) for controlling the hydraulic fluid provided to the rock drill cylinder (7), wherein the rock drilling machine (1) comprises at least one sleeve element (10) in accordance with any one of the preceding claims or a sleeve arrangement according to claim 13, of which the sleeve element (10) is provided around the valve slide (8) inside the cylindrical space (26).

17. The rock drilling machine (1) according to claim 15 or 16, wherein the drain outlet line (22) is arranged at an axial end (27, 28) of the cylindrical space (26) of the housing (2).

18. The rock drilling machine (1) according to claim 15, 16 or 17, wherein the rock drill cylinder (7) is made of a casted metal or alloy.

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