Dct-exhaust driven cooling

Abstract

Disclosed is a method and a rock drilling apparatus (10) arranged for cooling devices of the rock drilling apparatus (10). The method comprises, flushing a drill hole (52) with compressed air by flushing means, sucking at an opening (54) of the drill hole (52) by collecting means (16), for collecting an outgoing airstream (20) including drill cuttings (53) from the drill hole (52), leading the airstream (20) including drill cuttings (53) into a separating means (17), separating the drill cuttings (53) from the airstream (20) by leading the airstream (20) including drill cuttings (53) through the separating means (17), directing the airstream (20) into a first defined volume (14) by directing means (18), thereby entraining air (21) positioned at heat-generating devices (15) in the first defined volume (14), leading the directed airstream (20) and the entrained air (21) through an outlet means (19) out from the first defined volume (14).

Description

DCT-EXHAUST DRIVEN COOLINGTechnical field

[0001] The present disclosure relates generally to use exhaust air from a DCT- system (DCT=Dust Collecting Technique) to cool components / devices of a rock drilling apparatus, by directing an exhaust airstream from the DCT-system into a defined volume, in which heat-generating components / devices are arranged. By directing the exhaust airstream from the DCT-system into the defined volume, the DCT-airstream works as a propulsion force such that air from the defined volume is entrained, and by evacuating the DCT-airstream and the entrained airstream out from the defined volume, the components within the defined volume are cooled in a more efficient way and the DCT-system is used in a more efficient way.Background

[0002] Rock drilling machines used for example within the mining industry generate heat from different actuators and power sources and this heat needs to be removed. The heat-generating components / devices are typically arranged in one or several defined volumes, such as a volume limited by a chassis and an “engine casing” (hood) or the like. Typically, this heat is removed by pushing air over a radiator by a designated fan. Excessive heat may also be vented using an ejector propulsion, where a high velocity air stream is generated by a dedicated fan and which airstream will pull along surrounding air which is close to the high velocity airstream. Example of known solutions for ejector driven heat removal directs air so that it will pull along ambient air from the engine area and expel the warm air on the outside of the machine and replacing same air by cooler air. This is as mentioned handled by dedicated fans or the like, which task is to remove heat and cool heat-generating components of the machine.

[0003] Rock drilling machines within the mining industry may be equipped with dust collecting technique for collecting dust from the drill hole, which technique often is called DCT (Dust Collector Technique). Within the field of DCT, a combination of flushing air in combination with supplying liquid into a drilling hole isused for dust or drill cuttings removal from a drill hole. One example is presented in WO 2010 / 034889 A1.

[0004] Known solutions using DOT, flushes the drill hole with air or as mentioned above, a combination of flushing air and supplying liquid. The flushing of the drill hole with air may use compressed air, which causes an outgoing airstream from the drill hole, which airstream is substantially opposite the drill direction. The outgoing airstream is used for evacuating / removing drill cuttings out of the drill hole. The DCT-system includes collecting means which sucks close to the surface of the drill hole opening, to collect the outgoing airstream including drill cuttings. The airstream is led to a separating means of some kind, which may include a filter or the like, wherein the drill cuttings is removed from the airstream. The filtered DCT airstream is then let out into the ambient air outside the drill rig / the drilling machine.

[0005] Especially during the actual drilling operation by the drill rig, a lot of heat is generated in the components and for drill rigs using DCT for evacuating drill cuttings, a compressor is used for causing the flushing of the drill hole, wherein the compressor is one of the most intensive heat generators. Since the DCT- equipment is predominantly used in conjunction with drilling, the “vacuum ejection” of the outgoing airstream including drill cuttings is active during the highest need for heat removal of the drill rig components. A problem with the DCT is that the energy consumption is high during operation.

[0006] One problem within the field is that the removal of drill cuttings and heat costs installed power and energy, when using the DCT-equipment for removing drill cuttings and further that a dedicated fan for removing the heat caused by the drilling and the DCT-equipment must be used.

[0007] Thus, there is a need for a method and an improved rock drilling apparatus which method and apparatus take care of the above problems.Summary

[0008] It is an object of the disclosure to address at least some of the problems and issues outlined above. An object of aspects of the present disclosure is to provide a method for cooling parts / devices of a rock drilling apparatus. Another object of aspects of the present disclosure is to provide a rock drilling apparatus which is arranged to enable the method.

[0009] According to one aspect, a method for cooling heat-generating devices of a rock drilling apparatus is disclosed. The method comprises a number of activities which are performed during drilling of a drill hole in ground, from a ground surface in a drill direction. The method comprises flushing the drill hole with compressed air by flushing means, wherein an outgoing airstream from the drill hole is created by the flushing of the drill hole. The outgoing airstream is substantially opposite the drill direction and the airstream is thereby arranged for evacuating / removing drill cuttings out of the drill hole. The method further comprises sucking at the ground surface of the opening of the drill hole by collecting means, for collecting the outgoing airstream including drill cuttings from the drill hole. It is understood that the sucking may preferably be performed in close proximity of the drill hole, or at least close to the drill hole for having a good collecting effect. The collecting means may comprise means for covering a “suction area”, such as a hood or the like, and further a hose, a duct or the like. The method further comprises leading the airstream including drill cuttings, for example by the hose / duct of the collecting means, into a separating means, which separating means is arranged to separate drill cuttings from the airstream. The method further comprises separating the drill cuttings from the airstream by leading the airstream including drill cuttings through the separating means and the method further comprises directing the airstream that has been separated from the drill cuttings into a first defined volume of the rock drilling apparatus by directing means, thereby entraining air which is positioned at heat-generating devices arranged in the first defined volume. By entraining is meant that the airstream functions as a propulsion force in the defined volume, wherein surrounding air is drawn in, into the airstream / is drawn along the airstream, which by that “transports” the entrained air in the airflow direction. The directing means may be a pipe, a duct, or the like, which ends in thefirst defined volume, and which is arranged to lead the airstream further from the separating means and into the first defined volume and also to direct the airstream in the first defined volume (such that heat-generating parts are cooled down effectively). The method further comprises leading the directed airstream and the entrained air through an outlet means leading out from the first defined volume. The first defined volume is a volume in which at least one heat-generating device / component is arranged, and which defined volume has at least some entry openings arranged for letting ambient air (outside the first defined volume / the machine) in, when leading the directed airstream and the entrained air through the outlet means, out from the first defined volume. Otherwise, a vacuum would occur.

[0010] By such a method, an energy saving way for cooling devices of a drill rig by using an airstream of a DCT-system is achieved. By directing the exhaust air from the DCT-system and use it as a propulsion force within a defined volume in which heat-generating components are arranged, an effective and cost-efficient cooling is achieved. This, since air from the defined volume is entrained by the DCT-airstream and the evacuation of the DCT-airstream and the entrained airstream by leading it out from the defined volume, cools the components in an efficient way and the under-pressure within the defined volume causes cooler air from outside the machine to be drawn in into the defined volume. By the inventive method, no extra energy and equipment is needed to cool heat-generating components / devices of the drilling apparatus and the cooling is as most effective when the cooling need is great, that is during DCT-evacuation of drill cuttings.Known solutions let the DCT-airstream flow out from the separating means out into the free (to the air outside the first defined volume or outside the machine) and uses a separate fan for cooling the components in a defined volume, why the inventive method is far better concerning both energy consumption as well as cooling efficiency. The latter, since the DCT-airstream is directed into the first defined volume such that air near / close to the heat-generating components is effectively drawn into and along the directed DCT-airstream, and the leading of the total airstream (DCT + warm air) towards the outlet and out from the first defined volume evacuates the warm air effectively.

[0011] According to a disclosure, the method further comprises, before the step of directing the airstream into the first defined volume, directing the airstream that has been separated from the drill cuttings through a first contraction means. The first contraction means is arranged downstream the separating means and the first contraction means has a smaller cross-section compared to a cross-section of the separating means, in a flow direction of the airstream. By this, the DCT-airstream is accelerated to a higher speed than it has at least into the separating means (which normally has a large filtration area / separation area to separate drill cuttings effectively), and the higher speed of the airstream is used to direct the airstream in an effective ways and to get a strong propulsion force. The directed and strong propulsion force of the airstream gains a good result of entraining warm or hot air from the first defined volume and into the airstream, when the airstream is directed into the first defined volume. The leading of the total airstream towards the outlet of the first defined volume is also managed in a more effective way by a high speed of the airstream. The first contraction means may be a hose, a duct, a pipe or the like. Typically, the collecting means comprises some kind of hose or duct for leading the DCT-airstream from the opening of the drill hole to the separating means. This hose or duct typically has a smaller cross-section than the separating means, and the airstream is lead from the collecting means with a relatively high airspeed and when the DCT-airstream enters the separating means, the airspeed is reduced by that the separating means has a larger cross-section compared to the hose / duct of the collecting means. Thereby, the drill cuttings may be separated from the airstream, for example by a filter of other separation means. After this, the airstream is as mentioned led / directed through a first contraction means, which as mentioned may be a hose, a duct, a pipe or the like, wherein the speed of the DCT-airstream without drill cuttings increases. This to get an effective propulsion force which is possible to direct.

[0012] According to a disclosure, the method further comprises, after the step of directing the airstream through the first contraction means and before the step of directing the airstream into the first defined volume, directing the airstream through a second contraction means arranged downstream the first contraction means and upstream the first defined volume in a flow direction of the airstream, wherein thesecond contraction means has a smaller cross-section compared to a crosssection of the first contraction means. This alternative may be used gain an even more effective entraining of warm air from the first defined volume into the airstream, since the contraction means may be designed according to the Venturi effect or the like. The Venturi effect is the reduction in fluid pressure which is achieved when a fluid flows through a constricted section of a pipe or the like, wherein a more effective entraining of surrounding air is achieved, and by that a more effective cooling of the heat-generating components in the first defined volume, compared to known art.

[0013] According to a disclosure, the method further comprises, before the step of leading the directed airstream out from the first defined volume, directing the airstream through a third contraction means arranged at the outlet means of the first defined volume. The third contraction means may for example be arranged as funnel-like guiding means, which extends from the outlet of the first defined volume and into the first defined volume. This means that the third contraction means is arranged to better guide or lead the airstream out from the first defined volume wherein it tapers in direction from the first defined volume towards the outlet of the first defined volume. By that, the Venturi effect may be utilized also for the combined airstream (DCT + entrained air) out from the first defined volume, for higher efficiency of the cooling effect.

[0014] According to one aspect, a rock drilling apparatus is disclosed. The rock drilling apparatus comprises a drill rig, which comprises a drill for drilling a drill hole in ground, from a ground surface in a drill direction. The rock drilling apparatus comprises further comprises a chassis, which in turn comprises at least a first defined volume in which at least one heat-generating device / component of the rock drilling apparatus is arranged. The heat generating component may one or a plurality of heat-generating components. The rock drilling apparatus further comprises flushing means, arranged for flushing the drill hole by a compressed air stream. The flushing thereby creates an outgoing airstream, which is substantially opposite the drill direction, which is used for evacuating / removing drill cuttings out of the hole. This is normally called DCT-technique (Dust Collecting Technique)within the field of rock drilling. Further, the rock drilling apparatus comprises collecting means which are arranged for sucking at an opening of the drill hole and for collecting the outgoing airstream including drill cuttings from the drill hole. The rock drilling apparatus further comprises separating means, arranged for separating drill cuttings from the DCT-airstream, and directing means, arranged for directing the airstream from the separating means into the first defined volume of the rock drilling apparatus. The directing means comprises an outlet opening arranged to let the airstream out from the directing means and the rock drilling apparatus further comprises outlet means arranged for letting out the airstream from the first defined volume.

[0015] Such a rock drilling apparatus, arranged with a DCT-system for separating drill cuttings from the DCT-airstream, is arranged to use the DCT- airstream to cool heat-generating components arranged into a first defined volume (such as a motor compartment) of the rock drilling apparatus, in a very effective way. This, by that the apparatus is arranged to direct the DCT-airstream such that the airstream functions as a propulsion force which entrains warm air situated at (around) heat-generating components in the first volume, wherein the components are cooled down since the warm air is evacuated effectively from the first defined volume by being “carried” by the airstream through the first defined volume and out from the same, and replaced by cooler air from outside the first defined volume. The latter finds its way into the first defined area either through gaps, holes, vents or the like because of the under-pressure caused by the airstream leaving the first defined volume.

[0016] According to a disclosure, the directing means comprises a first contraction means arranged downstream the separating means, which first contraction means has a smaller cross-section compared to a cross-section of the separating means, in a flow direction of the airstream. By this, the DCT-airstream is accelerated to a higher speed than it has at least into the separating means and the higher speed of the airstream is used to direct the airstream in an effective ways and to get a strong propulsion force. The first contraction means may be a hose, a duct, a pipe or the like.

[0017] According to a disclosure, the directing means comprises a second contraction means, arranged downstream the first contraction means and upstream the first defined volume in a flow direction of the airstream, wherein the second contraction means has a smaller cross-section compared to the crosssection of the first contraction means. This gains an effective entraining of warm air from the first defined volume into the airstream, since the contraction means may be designed according to the Venturi effect or similar, which gains an effective use of the airstream for enabling under-pressure in the first defined volume and for an effective admixture of warm air into the passing airstream.

[0018] According to a disclosure, the outlet means of the first defined volume comprises a third contraction means. The third contraction means may be arranged as funnel-like guiding means for effective guiding of the airstream including the entrained air towards the opening and out from the first defined volume.

[0019] According to a disclosure, the third contraction means has an extension from an outlet of the outlet means and inwards into the first volume, such that a cross-section of the third contraction means decreases in direction towards the outlet of the first defined volume. The third contraction means may be arranged as mentioned above, a funnel-like guiding means, which extends from the outlet of the first defined volume and into the first defined volume. This means that the third contraction means is arranged to better guide or lead the airstream out from the first defined volume wherein it tapers in direction from the first defined volume towards the outlet of the first defined volume (in the airstream direction). By that, the Venturi effect may be utilized also for the combined airstream (DCT + entrained air) out from the first defined volume, for higher efficiency of the cooling effect.

[0020] According to a disclosure, the outlet opening of the directing means is arranged in the third contraction means. This means that the DCT-airstream enters the first defined volume “inside” the third contraction means, wherein an under-pressure is established in the third contraction. As mentioned, the third contraction may be a funnel-like guiding means, and for example it may bearranged as a “collecting cone”, and the under-pressure causes an even higher speed of the airstream why warm / hot air from the area of the heat-generating components is entrained into the airstream in an even more efficient way.

[0021] According to a disclosure, the rock drilling apparatus further comprises a heat exchanger arranged in the first defined volume, preferably near the heatgenerating components. The DCT-airstream may then be directed to entrain air from the area of the heat exchanger, or through the heat exchanger, wherein air is drawn from the heat-generating components, through the heat exchanger, by the propulsion force of the directed airstream from the DCT. By that, media inside the heat exchanger is warmed by the entrained air through the same and the media may be circulated and cooled elsewhere. This provides that cooling may be utilized around the heat exchanger. Other possibilities are also possible, for example if the heat exchanger is positioned such that outside air which enters the first volume due to the under-pressure caused by the DCT-airstream through into / through the first volume, may pass the heat exchanger, remote positions (volumes) of the rock drilling apparatus may be cooled by the DCT-airstream, indirectly so to speak.

[0022] Further possible features and benefits of this solution will become apparent from the detailed description below.Brief description of drawings

[0023] The invention is now described, by way of example, with reference to the accompanying drawings, in which:

[0024] Fig. 1 shows an illustration of a rock drilling apparatus according to the invention, which performs a rock drilling operation at a working site.

[0025] Fig. 2a-b show illustrations of the rock drilling apparatus of Fig.1 in a horizontal respective a vertical section view.Detailed description

[0026] In the following, different examples of a rock drilling apparatus 10 according to the present disclosure are described. The rock drilling apparatus 10 disclosed herein is illustrated by simplified illustration and may be realized in many different forms and should not be construed as being limited to the examples set forth herein. Like numbers in the drawings refer to like elements throughout.

[0027] Figs. 1 shows a simplified illustration of the rock drilling apparatus 10 when performing a rock drilling operation at a working site. The rock drilling apparatus comprises a drill rig 11 with a drill 12 and further a chassis 13. The chassis 13 of the rock drilling apparatus 10 comprises a first defined volume 14, typically an enclosed volume limited by a casing or hood. The first defined volume 14 comprises a number of heat generating devices 15 (see Fig.2a-b), for example compressor, engine, electrical devices etc. The rock drilling apparatus 10 further comprises a so-called dust collecting technique (DCT) for collecting dust / drill cuttings from a drill hole. The DCT-system of the rock drilling apparatus 10 thus comprises a flushing means (not visible) which normally is arranged at (near or close to) an end of the drill 12, and during drilling of a drill hole 52 in ground 50, from a ground surface 51 in a drill direction d, the flushing means flushes the drill hole 52 with compressed air, which causes an outgoing airstream 20 from the drill hole 52. The outgoing airstream 20 is substantially opposite the drill direction d. The outgoing airstream 20 is used for evacuating / removing drill cuttings 53 out of the drill hole 52. The DCT-system comprises collecting means 16, which sucks close to the ground surface 51 of the drill hole 52, near an opening 54 of the drill hole 52, to collect the outgoing airstream 20 including drill cuttings 53. The airstream 20 is led by the collecting means 16 to a separating means 17, which may include a filter or the like, wherein the drill cuttings 53 is removed from the airstream 20. The collecting means 16 may comprise means for covering a “suction area”, such as a hood or the like (not visible), and further a hose, a duct or the like for leading the airstream 20 to the separating means 17. The filtered DCT- airstream 20 is then directed into the first defined volume 14 by a directing means 18 and is further directed towards an outlet means 19 of the first defined volume 14, such that the air inside the first defined volume 14 is entrained by thepropulsion force of the airstream 20. By that, the warm air inside the first defined volume 14 including the air around the heat-generating components, leaves the first volume 14 together with the DCT-airstream 20 and is replaced by cooler air 22 from outside the first defined volume 14. This “outside air” 22 may enter the first defined volume 14 through normal leaks or vents, which leads from the outside into the first defined volume 14. Thus, an effective heat-removal is achieved, and the heat-generating components are cooled down.

[0028] Fig. 2a-b show simplified illustrations of the rock drilling apparatus 10 in a horizontal section view (Fig. 2a) respective a vertical section view (Fig. 2b). When the rock drilling apparatus 10 is drilling a hole, the DCT-system simultaneously flushes the drill hole with compressed air. The compressor and other heatgenerating devices 15 heats up air inside the first defined volume 14 and these components / devices need to be cooled down. By the inventive method and apparatus, the DCT-airstream including drill cuttings 53 is collected by the collecting means 16 at the opening 54 of the drill hole 52 (see Fig. 1 ) and lead to the separating means 17, where it is filtered or separated such that the drill cuttings 53 gets separated from the DCT-airstream 20. Typically, the separating means 17 has a larger cross section compared to the hose / duct of the collecting means 16, why the airstream 20, which travels in the collecting means 16 has rather high speed. When the airstream 20 enters the separating means 17, the airspeed is lowered due to the difference in cross-section (or large volume in the separating means 17), wherein the drill cuttings 53 “falls out” or is taken care of in some way. Then, the DCT-airstream 20 (without drill cuttings 53) is directed into the first defined volume 14 by the directing means 18, which in the preferred disclosure is a first contraction means 18b in the form of a duct, hose or pipe 18b, arranged downstream the separating means 17. The first contraction means 18b has a smaller cross-section compared to a cross-section of the separating means 17. This means that the speed of the DCT-airstream 20 gets high again in the directing means 18 / first contraction means 18b and the DCT-airstream 20 leaves the directing means 18 / contraction means 18b through an outlet opening 18a of the directing means 18 / contraction means 18b. By that, the warm air inside the first defined volume 14 including warm air 21 around the heat-generatingcomponents, leaves the first volume 14 together with the DCT-airstream 20 and is replaced by cooler air 22 from outside the first defined volume 14.

[0029] The directing means 18 may comprise a second contraction means (not visible in any figures), which then is arranged downstream the first contraction means 18b and upstream the first defined volume 14 in a flow direction of the airstream 20, wherein the second contraction means has a smaller cross-section compared to the cross-section of the first contraction means 18b. This gains an effective entraining of warm air 21 from the first defined volume 14 by the airstream 20, since the contraction means by that may be designed according to the Venturi effect or similar, which gains an effective use of the airstream 20 for enabling under-pressure in the first defined volume 14 and for an effective admixture of warm air 21 from the first defined volume 14 into the passing airstream 20.

[0030] According to an embodiment of the disclosure, the outlet means 19 of the first defined volume 14 comprises a third contraction means 19a. which may be arranged as funnel-like guiding means 19a, for effective guiding of the airstream 20 including the entrained air 21 towards an opening out from the first defined volume 14. The third contraction means 19a has an extension from an outlet 19b of the outlet means 19 and inwards into the first volume 14, such that a crosssection of the third contraction means 19a decreases in direction towards the outlet 19b of the first defined volume 14. This means that the third contraction means 19b is arranged to better guide or lead the combined / total airstream 20, 21 out from the first defined volume 14, in the airstream direction. By that, the Venturi effect may be utilized also for the combined airstream (DCT-airstream 20 + entrained air 21 ) out from the first defined volume 14, for higher efficiency of the cooling effect inside the first defined volume 14. As can be seen in Fig.2a-b, the outlet opening 18a of the directing means 18 is arranged in the third contraction means 19a, which means that it ends inside the third contraction means 19a (the cone or funnel-like guiding means). This means that when the DCT-airstream 20 enters the first defined volume 14 “inside” the third contraction means 19a, an under-pressure is established in the third contraction means 19a, which gains ahigher entraining of warm entrained air 21 from the first defined volume 14, wherein warm / hot air 21 from the area of the heat-generating components is entrained into the airstream 20 in an even more efficient way.

[0031] Although the description above contains a plurality of specificities, these should not be construed as limiting the scope of the concept described herein but as merely providing illustrations of some exemplifying embodiments of the described concept. It will be appreciated that the scope of the presently described concept fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the presently described concept is accordingly not to be limited. Reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more." All structural and functional equivalents to the elements of the abovedescribed embodiments that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed hereby. Moreover, it is not necessary for an apparatus or method to address each and every problem sought to be solved by the presently described concept, for it to be encompassed hereby. In the figures, a broken line generally signifies that the feature within the broken line is optional.

Claims

CLAIMS1 . Method for cooling devices of a rock drilling apparatus (10), the method comprising, during drilling of a drill hole (52) in ground (50), from a ground surface(52) in a drill direction (d),- flushing the drill hole (52) with compressed air by flushing means, thereby creating an outgoing airstream (20) from the drill hole (52), which airstream (20) is substantially opposite the drill direction (d), for evacuating / removing drill cuttings(53) out of the drill hole (52),- sucking at an opening (54) of the drill hole (52) by collecting means (16), for collecting the outgoing airstream (20) including drill cuttings (53) from the drill hole (52),- leading the airstream (20) including drill cuttings (53) into a separating means (17),- separating the drill cuttings (53) from the airstream (20) by leading the airstream (20) including drill cuttings (53) through the separating means (17), characterized in that the method further comprises- directing the airstream (20) that has been separated from the drill cuttings (53) into a first defined volume (14) of the rock drilling apparatus (10) by directing means (18), thereby entraining air (21 ) which is positioned at heat-generating devices (15) arranged in the first defined volume (14),- leading the directed airstream (20) and the entrained air (21 ) through an outlet means (19) leading out from the first defined volume (14).

2. Method according to claim 1 , wherein the method further comprises:- before the step of directing the airstream (20) into the first defined volume (14), directing the airstream (20) that has been separated from the drill cuttings (53) through a first contraction means (18b) arranged downstream the separating means (17), which first contraction means (18b) has a smaller cross-section compared to a cross-section of the separating means (17), in a flow direction of the airstream (20).

3. Method according to claim 2, wherein the method further comprises:- after the step of directing the airstream (20) through the first contraction means(18b) and before the step of directing the airstream (20) into the first defined volume (14), directing the airstream (20) through a second contraction means arranged downstream the first contraction means (18b) and upstream the first defined volume (14) in a flow direction of the airstream (20), wherein the second contraction means has a smaller cross-section compared to a cross-section of the first contraction means (18b).

4. Method according to any of the preceding claims, wherein the method further comprising:- before the step of leading the directed airstream (20) out from the first defined volume (14), directing the airstream (20) through a third contraction means (19a) arranged at the outlet means (19) of the first defined volume (14).

5. A rock drilling apparatus (10) comprising:- a drill rig (11 ), which comprises a drill (12) for drilling a drill hole (52) in ground (50), from a ground surface (51 ) in a drill direction (d),- a chassis (13), which comprises at least a first defined volume (14) in which heatgenerating components (15) of the rock drilling apparatus (10) are arranged,- flushing means for flushing the drill hole (52) by a compressed air stream, thereby creating an outgoing airstream (20), which is substantially opposite the drill direction (d), for evacuating / removing drill cuttings (53) out of the drill hole (52),- collecting means (16) arranged for sucking at an opening (54) of the drill hole (52), for collecting the outgoing airstream (20) including drill cuttings (53) from the drill hole (52),- separating means (17) arranged for separating drill cuttings (53) from the airstream (20),- directing means (18), arranged for directing the airstream (20) from the separating means (17) into the first defined volume (14) of the rock drilling apparatus (10), wherein the directing means (18) comprises an outlet opening (18a) arranged to let the airstream (20) out from the directing means (18),- outlet means (19) arranged for letting out the airstream (20) from the first defined volume (14).

6. Rock drilling apparatus according to claim 5, wherein the directing means(18) comprises a first contraction means (18b) arranged downstream the separating means (17), which first contraction means (18b) has a smaller crosssection compared to a cross-section of the separating means (17), in a flow direction of the airstream.

7. Rock drilling apparatus according to claim 6, wherein the directing means (18, 18b) comprises a second contraction means, arranged downstream the first contraction means (18b) and upstream the first defined volume (14) in a flow direction of the airstream (20), wherein the second contraction means has a smaller cross-section compared to the cross-section of the first contraction means (18b).

8. Rock drilling apparatus according to any of claims 5 - 7, wherein the outlet means (19) of the first defined volume (14) comprises a third contraction means (19a).

9. Rock drilling apparatus according to claim 8, wherein the third contraction means (19a) has an extension from an outlet (19b) of the outlet means (19) and inwards into the first volume (14), such that a cross-section of the third contraction means (19a) decreases in direction towards the outlet (19b) of the outlet means(19) of the first defined volume (14).

10. Rock drilling apparatus according to any of claims 8 - 9, wherein the outlet opening (18a) of the directing means (18) is arranged in the third contraction means (19a).

11. Rock drilling apparatus according to any of claims 5 - 10, further comprising a heat exchanger arranged in the first defined volume (14).

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