ROCK DRILLING RIG AND METHOD FOR DRILLING

BACKGROUND OF THE INVENTION

[0001] The invention relates to a rock drilling rig comprising a movable carrier, on which at least one drilling boom provided with a drilling unit is arranged. The drilling unit comprises a rock drill machine and a tool connected to it for drilling a drill hole. The driving power required by the rock drilling rig is generated by means of a driving engine. The rock drilling rig further comprises a flushing system provided with a compressor generating compressed air that is conveyed along a flushing duct to the tool and further into the drill hole to be drilled. Between the driving engine and the compressor, there is a transmission device for transmitting rotation power. Further, the invention relates to a method of drilling rock with a rock drill machine.

[0002] The objects of the invention are defined in greater detail in the preambles of the independent claims.

[0003] When rock is drilled with a rock drill machine, the tool is pushed against rock by means of a feed device. Further, the tool is rotated by means of a rotating device around its longitudinal axis, and at the same time, the tool is given impact pulses by means of a percussion device, whereby the tool breaks rock. When rock is being broken, rock material, i.e. chippings, is detached from it, which material needs to be flushed out of the drill hole. Flushing is typically arranged in such a way that compressed air is fed through the tool to the bottom of the drill hole, whereby the compressed air pushes the chippings out of the drill hole. The compressed air required in the flushing is generated with a compressor the performance of which is dimensioned according to the maximum flushing amount. However, the drilling situations and conditions, such as the height of the drilling location relative to the sea level and the quality of the rock to be drilled, vary, whereby also the required flushing amount varies. The compressor is usually rather large in size, which causes problems to the layout of the carrier of the rock drilling rig. Further, the compressor is connected by means of fixed transmission of transmission members to the combustion engine of the rock drilling rig, which means that it is used unnecessarily also when the drilling is not performed and there is no need for flushing. In such a case, the compressor causes undue fuel consumption. Furthermore, a high-power compressor connected with fixed transmission to the

engine makes the cold start of the combustion engine significantly more difficult.

BRIEF DESCRIPTION OF THE INVENTION

[0004] An object of the invention is to provide a novel and improved rock drilling rig as well as a method of drilling rock.

[0005] The rock drilling rig according to the invention is characterized in that the flushing system comprises at least two compressors; and that at least one compressor is disconnectable from driving power obtained from the driving engine by means of the transmission device and, on the other hand, connectable by means of the transmission device, according to the need.

[0006] The method according to the invention is characterized by using at least two compressors in generating the compressed air required in the flushing, i.e. a first compressor and a second compressor; and by disconnecting transmission in at least one compressor in predetermined situations.

[0007] An idea of the invention is that the flushing system of the rock drilling rig comprises two or more compressors for generating the compressed air required in the flushing. The power and number of compressors is dimensioned in such a way that the maximum flushing required can be achieved in all conditions. Further, the transmission device comprises means for disconnecting one or more compressors from transmission in such a way that the compressor in question can be completely disconnected and reconnected, as required.

[0008] An advantage of the invention is that positioning two or more compressors on a carrier is easier than positioning one compressor with a high power and a large size. Thus, the layout of the carrier can be arranged more freely and there is no need to increase the size of the carrier. Further, when there are more compressors, they can be positioned in a space-saving way in connection with the driving engine and the transmission device, which may also contribute to providing a compact rock drilling rig. A further advantage is that starting the driving engine in particularly cold conditions is easier when one or more compressors or all compressors of the system can be disconnected from rotation of the driving engine for the duration of the starting. Further still, the energy consumption of the driving engine is significantly reduced because one or more compressors can be disconnected from transmission when the need for flushing air is small or when the flushing is not required at

all. Conventionally, a compressor has been disconnected by closing the suction duct of the compressor. Although the compressor is then rotated without pressure output, according to experience the compressor still takes approximately 70 % of the normal input power and causes energy and fuel consumption according to that. Further, the operating costs in the arrangement according to the invention may be lower, owing not only to said fuel-effectiveness but also because at least with some of the compressors the number of operating hours may be significantly smaller and thus the need for maintenance may be smaller and the service life longer. Yet another advantage is that a system provided with two or more compressors in accordance with the invention is surprisingly more inexpensive than one high-power compressor when taking into account the same maximum generation of compressed air.

[0009] The idea of an embodiment is that the compressor can be connected and disconnected while the driving engine is running, without having to stop the driving engine for the duration of connecting and disconnecting. The transmission device may comprise for instance a mechanical clutch between the driving engine and the compressor.

[0010] The idea of an embodiment is that the flushing system comprises two or more compressors with substantially equal powers. The control unit of the rock drilling rig may be arranged to prioritize one compressor as the main compressor and to connect and disconnect the auxiliary compressors, as required. The control unit may be arranged to vary the connecting order of the compressors, whereby the compressors are loaded evenly during their service life.

[0011] The idea of an embodiment is that the flushing system comprises two compressors with different powers. The compressor with a lower power has been connected by means of fixed transmission to be used by the driving engine. In contrast, the compressor with a higher power can be disconnected from transmission when the compressed air flow generated by it is not needed. An advantage of this solution is that when the compressor with a lower power is fixedly connected to be used by the driving engine, the compressed air generated by it can be continuously used for example for the cleaning of filters of the flushing system, maintenance work and the like. The compressor with a lower power does not, however, make the starting of the driving engine more difficult, and the increase in the energy and fuel consumption caused by it is not a significant factor. The compressor with a higher power

is connected only when it is needed and disconnected when not needed any more.

[0012] The idea of an embodiment is that the compressors have fixed displacement. Such compressors are structurally simple, inexpensive and durable in operation.

[0013] The idea of an embodiment is that the transmission device comprises a mechanical gear system, for example a gear box. Further, the transmission device comprises at least one mechanical clutch for disconnecting transmission between at least one compressor and the driving engine. An advantage of a mechanical gear system and a mechanical clutch is good efficiency compared with hydraulic transmission, for example. Further, mechanical transmission components are durable and inexpensive to manufacture.

[0014] The idea of an embodiment is that the transmission device comprises a mechanical transmission gear system and a mechanical clutch. The clutch is arranged to be used by means of a hydraulic actuator. Further, at least one hydraulic pump has been arranged to be operated by the transmission device to generate hydraulic pressure in the hydraulic circuit. The actuator of the clutch is connected to the hydraulic circuit. When the driving engine operates the hydraulic pump and generates a sufficient hydraulic pressure in the hydraulic circuit, the hydraulic actuator automatically connects the mechanical clutch. Thus, the power is transmitted via the clutch to the compressor. When the driving engine is stopped, no hydraulic pressure prevails in the hydraulic circuit, whereby the actuator moves the clutch into the open position. When the driving engine is started the next time, transmission has been disconnected in the compressor in question, which makes the starting easier.

[0015] The idea of an embodiment is that the rock drilling rig comprises a control unit, in which at least one control strategy is installable to control the operation of the compressors. The control unit is arranged to control the transmission device to disconnect at least one compressor in any of the following situations: starting of the driving engine, tramming of the rock drilling rig, cleaning and maintenance of the flushing system.

[0016] The idea of an embodiment is that the flushing agent duct or tank is provided with at least one sensor, and the measurement information obtained from this sensor is transmitted to the control unit. The control unit monitors the need for pressure medium by means of the sensor and controls the connecting and disconnecting of the compressor on the basis of it. Further,

the control unit may monitor automatic cycles or control commands given by the operator and control the compressors on the basis of them.

[0017] The idea of an embodiment is that the driving engine, transmission device and compressors are arranged one after the other, whereby they form an elongated unit. The compressors are arranged side by side, whereby the number of compressors does not affect the length of the power unit. Such a power unit formed of a driving engine, a transmission device, compressors and possibly one or more hydraulic pumps is positioned crosswise on the carrier of the rock drilling rig. When two or more compressors with lower powers are used instead of one high-power compressor, the length of the power unit may be smaller, owing to which the width of the carrier can be reasonable. A compressor with a lower power is typically shorter than a high- power compressor.

[0018] The idea of an embodiment is that the driving engine is a combustion engine.

BRIEF DESCRIPTION OF THE FIGURES

[0019] Some embodiments of the invention are explained in greater detail in the attached drawings, in which

Figure 1 shows schematically a rock drilling rig to which the arrangement according to the invention can be applied;

Figure 2 shows schematically an arrangement for operating compressors; and

Figure 3 further shows schematically and in perspective a power unit formed of a combustion engine, transmission device and two compressors.

[0020] For the sake of clarity, embodiments of the invention are shown simplified in the figures. Similar parts are denoted with the same reference numerals.

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

[0021] The rock drilling rig 1 shown in Figure 1 comprises a movable carrier 2 provided with one or more drilling booms 3 with a drilling unit 4. The drilling unit 4 comprises a rock drill machine 5, which can be moved on a feed beam 6 by means of a feed device 7. The rock drilling rig 1 is used by means of a combustion engine 8 arranged on the carrier 2. Typically, the combustion engine 8 is a diesel engine. The power obtained from the combustion

engine 8 is used as the power source for, for example, en electric generator and hydraulic pumps, which generate the required energy for, for example, drive transmission, drilling and booms. Compressors 9a, 9b are also operated with it. The compressor 9 is used to generate compressed air, with which a drill hole 10 to be drilled can be flushed. Compressed air is fed along a flushing duct 11 of the flushing system to the rock drill machine 5 and further through a duct in a tool 12 into a drill hole 10. The tool 12 may comprise one or more drill rods and a drill bit 13 arranged at the outermost end thereof. The drill rods may be tubular pieces and the drill bit may have the required flushing ducts. The compressed air conveyed into the drill hole 10 pushes the chippings detached from the rock during the drilling out of the drill hole. The rock drilling rig 1 may comprise a dust collection system, by means of which the chippings may be sucked out of the drill hole 10 along hoses or the like suction ducts 14 to a dust separator 15. Further, compressed air may be used in generating oil mist to be used in lubricating the shank of the rock drill machine 5, in cleaning filters of the dust separator and in cleaning in connection with maintenance work.

[0022] As seen from Figure 1 , there are two compressors, i.e. a first compressor 9a and a second compressor 9b, which are connected by means of a transmission device 16 to be operated by the combustion engine 8. There may be more than two compressors as well, for example three or four. Further, the compressors may have equal or different powers. The compressed air generated by the compressors 9a, 9b can be conveyed into one common compressed air tank 17, or alternatively each compressor may have a separate compressed air tank. The transmission device 16 may be a mechanical gear system, for instance a gear box, by means of which the rotation speed of the combustion engine 8 is converted to be suitable for the compressors 9. Further, the transmission device 16 may comprise a clutch with which either one compressor or both compressors can be disconnected from transmission and reconnected. The clutch allows the compressor to be connected and disconnected while the combustion engine is running. The clutch may be any clutch suitable for the purpose, such as a disc clutch or a multiple-disc clutch. Connecting and disconnecting the clutch may take place by means of one or more actuators.

[0023] Further, the rock drilling rig 1 comprises one or more control units 18, which may be arranged in a cabin positioned on the carrier. The control unit 18 may also be a computer, a programmable logic or any other device

suitable for the purpose, by means of which the operation of the rock drilling rig 1 can be controlled interactively with the operator. The control unit 18 may be arranged to control the operation of the compressors 9 in accordance with a predetermined control strategy. Alternatively, the operator may give commands manually to control the operation of the compressors. Yet another option is that the control unit does not control the compressors at all but that their control is arranged to be automatic in another way, as will be described later in the context of Figure 3.

[0024] Figure 2 is a greatly simplified view of an arrangement for controlling the operation of the compressors 9a, 9b. The control unit 18 may control actuators 19a, 19b, with which mechanical clutches 20a, 20b can be used in such a way that the compressors 9a, 9b can be connected to and disconnected from transmission in accordance with the desired control strategy. The clutches 20a, 20b may be between a gear system 21 and the compressors 9a, 9b. The actuator 19 may be, for example, a hydraulic cylinder or another pressure-medium-actuated or even electric power member, which provides the required movement for connecting and disconnecting the clutch 20. By means of the gear 21 , the rotation speed obtained from the combustion engine 8 can be converted to be suitable for the compressors 9a, 9b. If required, a suitable rotation speed can be transmitted from the gear system to each compressor, or there may be a separate reduction or increase gear in connection with the compressor. The control unit 18 may control the actuators 19a, 19b to disconnect the clutches 20a, 20b for instance for the duration of starting the combustion engine 8. Further, also in other situations according to the control strategy, one or more compressors can be connected to transmission or disconnected from transmission. The compressed air obtained from the compressors 9a, 9b is conveyed along the flushing duct 11 to the tank 17 and further to the rock drill machine. In connection with the flushing duct 11 and the compressor 9, there may be required control members 22, such as valves, which allow, if required, the flow of the compressed air and the pressure to be influenced and, further, the feed of the compressed air to be controlled.

[0025] Furthermore, the control unit 18 may monitor the need for compressed air in the flushing system and, accordingly, connect the compressors to and disconnect the compressors from transmission. For monitoring, the flushing duct 11 may comprise one or more sensors 27 to measure the pressure or flow of the compressed air.

[0026] Figure 3 shows a compact power unit 23, which comprises a combustion engine 8, a transmission device 16, two compressors 9a, 9b and at least one hydraulic pump 24. The power unit 23 is relatively short, whereby it can be arranged crosswise T in relation to the longitudinal direction L of the carrier of the rock drilling rig. The compressors 9a, 9b may be connected to the transmission device 16 side by side or on top of each other. The hydraulic pump 24 may be connected with fixed transmission to the transmission device 16, whereby it begins to generate hydraulic pressure in a hydraulic circuit 25 once the combustion engine 8 is started. The first compressor 9a is disconnected from transmission with the clutch 20a when the combustion engine 8 has been stopped. In connection with the clutch 20a, there may be a hydraulic actuator 19a, which is connected to the hydraulic circuit 25 and arranged to connect the clutch 20a when the pressure in the hydraulic circuit 25 is sufficient. Further, in connection with the clutch 20a, there may be for instance spring members or the like, which disconnect the clutch 20a when the pressure in the hydraulic circuit 25 is lower than predetermined. When the combustion engine 8 is started, the first compressor 9a is not connected to transmission and thus it does not make the starting more difficult. After the starting, the hydraulic pump 24 generates hydraulic pressure in the hydraulic circuit 25 and automatically causes the actuator 19a to operate and the first clutch 20a to be connected. The second compressor 9b may be continuously connected to transmission, or in some cases there may also be a clutch in connection with it, by means of which the connecting to transmission can be controlled. It is also seen from Figure 3 that between the compressor and the transmission device 16 there may be a compressor-specific reduction gear 26 or the like transmission member.

[0027] It is also feasible to utilize CVT (Continuously Variable Transmission) technology in connecting and disconnecting the compressors and in controlling the power. For example, the solution disclosed in EP- 1 499 818-B1 can be used, in which a compressor connected mechanically to a planetary gear system is stoppable.

[0028] The compressors may be connected and disconnected in accordance with several different control strategies and situations. In cold conditions, one single compressor may be connected, and the flushing system may be operated to the normal operating temperature by means of it, whereby the heating of the system is controlled. In this way, sudden extensive heat

generation and problems resulting from it are avoided. Further, one high-power compressor may be disconnected when the drill hole has been drilled and the output of one lower-output compressor is sufficient to implement the cleaning cycle of the dust separator filters. After the cleaning cycle, also the lower- output compressor can be disconnected. Further still, the compressors may be connected and disconnected according to how high the drilling location is relative to the sea level. In high-altitude climates, for example in mountains, the atmospheric pressure is lower, whereby several compressors may be connected to provide sufficient output. When the same rock drilling rig is used closer to the sea level, one or more compressors may be disconnected because the atmospheric pressure is higher, and sufficient output of compressed air can be achieved more easily. The same rock drilling rig may thus be used without any structural changes in different altitudes and climates. In addition, a low output auxiliary compressor may be connected when particularly large drill holes are drilled and the need for flushing air is great. In ordinary drilling, the basic compressor is sufficient and the low-output auxiliary compressor can be kept disconnected. Further, one or more compressors or all compressors may be disconnected for the duration of the drive and the cold start of the combustion engine. It is feasible that one or more compressors are connected only during the drilling and the cleaning cycle of the dust separator filters. Connecting and disconnecting may, of course, be carried out in accordance with other control strategies as well.

[0029] It is to be noted that the idea of the invention may be applied by using different clutches, transmission elements and other mechanical machine parts.

[0030] In some cases the driving engine may be, instead of a combustion engine, for example an electric engine. Also in such a case, advantages presented in this application are achieved, for instance with regard to easier starting, durability and energy economy.

[0031] In one solution deviating from the above ones, the rock drilling rig comprises only one compressor. Connecting and disconnecting of this compressor can be controlled in accordance with any of the control situations presented in this application and by using means presented in this application to carry out the connecting. For instance, the compressor may be connected only for the duration of the drilling and the cleaning of the dust separator filters,

and otherwise it can be kept disconnected. In this way, above advantages are achieved with regard to cold start and energy economy, for example.

[0032] In some cases, features presented in this application may be used as such, irrespective of other features. On the other hand, features presented in this application may, if required, be combined to form different combinations.

[0033] The drawings and the related description are only intended to illustrate the idea of the invention. The details of the invention may vary within the scope of the claims.