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This application claims priority to and the benefit of the filing date of International Application No. PCT/EP2007/007287, filed Aug. 17, 2007, which application claims priority to and the benefit of the filing date of German Application No. 10 2006 038939.5, filed Aug. 18, 2006, both of which are hereby incorporated by reference into the specification of this application. 
     BACKGROUND 
     The invention relates to a shearer loader for underground mining, comprising a shearer loader body, comprising a respective cutting drum, fastened to a supporting arm, for each direction of travel of the shearer loader, comprising drive motors for moving the shearer loader and for moving the cutting drums, comprising at least one cooling water circuit for cooling the drive motors, comprising a spray system which comprises a spray water circuit having a respective feed line to the tools of the cutting drums, comprising a preferably common water connection for the water circuits, and comprising valves assigned to the water circuits for switching the water circuits on or off. 
     In the underground winning of minerals, in particular in underground coal winning, the spraying of spray water via nozzles onto the working face to be worked is prescribed for the suppression of dust. In this case, the longwall spraying is largely effected by means of the powered support assemblies, to which nozzles are attached at suitable points, such as the canopies for example, and these nozzles can be operated with high-pressure water at about 150-200 bar. Reference is made only by way of example to DE 195 37 448 A1. 
     With the increase in output effected in shearer loaders, the generation of dust and the risk of explosion in cutting operations increase. Whereas initially the cutting drums were sprayed from outside via water nozzles from the supporting arm, internal spraying, in which a water nozzle which can be supplied with spray water is assigned to each tool at the cutting drum, is also taking place in the meantime. The picks are sprayed at pressures of up to about 50 bar. 
     The lower water consumption of the spray systems which is achieved by the internal spraying in the meantime enables some of the cooling water to be directed away from longwall again in hoses via the cable trailing chain (cf. www.steinkohleportal.de). 
     DE 30 200 46 A1 discloses a shearer loader in which the water fed to the shearer loader is divided at a line branch point into a line branch for the cooling water circuit and a line branch for the spray water circuit, wherein both line branches are fed, downstream of the units to be cooled in the water circuit and downstream of volume regulating valves in both sub-circuits, to a 4/3-way directional valve in order to be able to carry out the spraying, as a function of the direction of travel of the shearer loader, at the respectively leading cutting drum solely with the water flowing in from the spray water circuit and at the trailing cutting drum solely with the water fed to the cooling water circuit. Since less dust to be controlled by means of the spraying collects at the trailing drum, the spraying at the trailing drum is to be effected only with the lower water volume from the cooling water circuit. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to improve the effectiveness of the water supply systems of shearer loaders. 
     To achieve this and other objects, it is proposed according to the invention that, in shearer loaders of the generic type, a respective control valve connected to one of the feed lines be arranged in return lines of the cooling water circuit, via which control valve the cooling water can be fed as spray water to the cutting drums as and when required. In the shearer loader according to the invention, the cooling water can therefore be fed, as and when required, to the spray nozzles at the cutting drums by opening the control valves and can be used there as spray water. An effective spray water supply which can be adapted to the respective ventilating conditions and mining conditions can therefore be provided at an overall lower requisite water flow rate for the shearer loader. Since the cooling water is fed to the cutting drums only as and when required, floor lift can at the same time be avoided to the greatest possible extent and it is no longer necessary to pump excess spray water away from the longwall. 
     In a preferred configuration according to the invention, a separate control valve is provided for each cutting drum. It is especially advantageous if both control valves are each connected via an intermediate line to the associated feed line for one of the cutting drums, each feed line preferably being provided, upstream of the inflow to the intermediate line, with a valve for separately switching the spray water circuit on and off and also preferably with a volume regulating valve. In this configuration, firstly the water volume fed to the cutting drums solely via the spray water circuit can be set via the volume regulating valve and secondly it is ensured that, if need be, in the event of excess accumulation of dust, both the spray water from the spray water circuit and the cooling water from the cooling circuit can be fed as spray water to the cutting drums. 
     Furthermore, a respective volume regulating valve can preferably be arranged in the intermediate lines and/or in the cooling water feed lines of some of or if need be of all the drive motors, to be cooled with the cooling water from the cooling water system, in order to be able to regulate in as optimum a manner as possible the water volume received and possibly delivered to the spray system. It is especially advantageous when some of or all the volume regulating valves can be activated or regulated for metered admission of spray water to the cutting drums. The activation can be effected, for example, via a primary activating unit, such as, for example, the longwall face control or the like. 
     A pressure limiting valve and/or a pressure regulating valve is expediently arranged downstream of the water connection in the common water feed to both water circuits in order to detect or avoid malfunctions due to the water volume, possibly established by the mines, and the water pressure for the spraying exceeding or falling below the threshold values. For example, in the event of a water supply that is too low, a limit value in relation to dust protection could be exceeded, for which reason the winning machine should be switched off or reduced in its output if this hazard situation is detected. Exceeding or falling below a threshold value may at the same time indicate obstruction of the nozzles or other malfunctions. In order to reliably detect this, it is also expedient if a volumetric flow sensor is arranged upstream of the pressure limiting valve. In order to avoid contamination of the circuits and clogging of the nozzles, it is also advantageous if a water filter, preferably a reversible flow filter, is arranged in the water feed upstream of the volumetric flow sensor. Furthermore, it is expedient if a branch point is formed downstream of the pressure limiting valve, said branch point opening with one branch into the cooling water circuit and with one or preferably two branch lines into separate spray water circuits for the individual cutting drums. 
     In a preferred configuration, the spray system has a first spray water circuit for the one cutting drum and a separate second spray water system for the other cutting drum, wherein the cooling water can be fed or is fed to the cutting drums, via the one respective or via the at least one respective control valve connected to the feed lines, as an additional volume of spray water with control valves open and valves open or solely as spray water with valves closed and control valves open. By the division of the fed water into separate spray water circuits for both cutting drums and by connecting the water from the cooling water circuits to the system as and when required, considerably more effective spraying optimized with regard to water consumption control can be realized. It may suffice to arrange in each case precisely one valve and one control valve for each sub-circuit in the spray water circuit and/or in the cooling water circuit in order to be able to carry out the spraying optionally only with cooling water, only with spray water or with the volumetric flows of cooling water and spray water. 
     According to a further configuration, at least two valves which can be activated independently of one another can be arranged between the water connection, in particular between the associated branch line of the spray water sub-circuit, and the respective feed line in the spray water circuit for each cutting drum, and/or at least two control valves which can be activated independently of one another can be arranged for each cutting drum between the return line and the respective feed line to the cutting drum in the cooling water circuit. By separate activation of the respective control valves and valves, not only can the volume of water for the spraying then actually fed to the cutting drums be set differently for the individual cutting drums, but the volume can also be adapted gradually to the requirements, with little outlay in terms of circuitry, in order to spray only the water volume required for dust control at the longwall, while the rest of the water is directed away from the longwall again via the return lines and a return hose. For further optimization and improvement in effectiveness, a volume regulating valve can be assigned to each valve in the spray water circuit. 
     Furthermore, in order to increase safety at the longwall, a branch to an extinguishing spray system which can preferably be switched on manually can preferably be arranged in the water circuit. Alternatively or additionally, a branch leading into a camera cleaning system which can be switched on and off and is intended for cleaning, for example, a monitoring camera for the longwall or the shearer loader can be arranged downstream of the pressure limiting valve. 
     These and other objects, aspects, features and advantages of the invention will become apparent to those skilled in the art upon a reading of the Detailed Description of embodiments set forth below taken together with the drawings which will be described in the next section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail and illustrated in the accompanying drawings which form a part hereof and wherein: 
         FIG. 1  shows a highly schematic simplified plan view of a shearer loader for underground mining; 
         FIG. 2  shows a diagram of the water circuits, provided in a shearer loader according to the invention in  FIG. 1 , for the cooling and spraying according a first exemplary embodiment; and 
         FIG. 3  shows a diagram of the water circuits for the cooling and spraying according to a second exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Referring now to the drawings wherein the showings are for the purpose of illustrating preferred and alternative embodiments of the invention only and not for the purpose of limiting same, 
     A shearer loader  1 , in particular for coal winning in underground mining, is shown in  FIG. 1  in a highly schematic simplified manner, said shearer loader  1  having a shearer loader body  2  which is movable on a rack laid parallel to the conveyor (not shown) at the longwall. Fastened to the shearer loader body  2  for both directions of travel of the shearer loader  1  are respective supporting arms  3 , on which in turn a cutting drum  4  is rotatably mounted for each direction of travel, said cutting drum  4  being fitted with a multiplicity of cutter picks (not shown) as processing tools, with which the minerals to be worked, such as coal in particular, are won at the working face. Water circulation systems (not shown in  FIG. 1 ) inter alia with a cooling water circuit for the drive systems of the individual units and motors of the shearer loader and also a spray system for the cutting drums  4  are integrated in the shearer loader body  2 , in the supporting arms  3  and in the cutting drums  4 , the construction of which water circulation systems will now be explained with reference to  FIG. 2 . 
     Of the shearer loader, only the two cutting drums  4  for the respective directions of travel are indicated in  FIG. 2 , where it can be seen in the schematic illustration according to  FIG. 2  that both cutting drums  4  are provided with a multiplicity of nozzles  5  which are preferably assigned directly to the processing tools and via which the spray water for dust suppression is sprayed out during the winning. In order to supply the nozzles  5  with spray water, water is fed to the shearer loader via at least one hose, which is preferably laid parallel to the trailing cable for the electrical power supply of all the units of the shearer loader, this water being fed via an inlet  11  common to all the water circuits  10 . This may preferably involve a low-pressure input for water at an average pressure of about 35-40 bar with a flow rate of, for example, about 300 l/min. Arranged downstream of the water inlet  11  in the water circuit  10  is a reversible flow filter  12 , via which impurities in the fed water can be filtered out in order to prevent contaminants in the water from leading to blockages in the sub-circuits or to blockages of the nozzles. Connected in turn downstream of the reversible flow filter  12  in the water circuit  10  is a combined flow-rate/water-pressure monitoring system  13  which comprises a flow sensor  14  and a pressure sensor  15  in order to determine the current pressure P and the current flow rate Q and to signal them via signal lines (not shown) to a primary controlling and evaluating device (likewise not shown). A pressure regulating valve  16  with downstream pressure limiting valve  17  with which the pressure of the water can be regulated to the desired range, here between 35 bar and 40 bar, are arranged downstream of the monitoring system  13 . 
     Arranged downstream of the two valves  16 ,  17  is a flow branch point or a flow divider  18 , from which a line branch  19  leads to a cooling circuit  30  and two further branch lines  20 A and  20 B lead to a respective control valve  21 A,  21 B, which can be connected to a common pilot control block  22  by actuating electromagnetic valves in order to feed the spray water as and when required either to the one cutting drum  4  via the branch line  20 A with valve  21 A open or to the other cutting drum  4  via the other branch line  20 B with valve  21 B open. Connected upstream of both valves  21 A,  21 B is a respective volume regulating valve  22 A,  22 B in order to be able to reduce to a suitable value the volume of spray water which is fed to the respective cutting drum  4  via the feed lines  23 A and  23 B, respectively, with control valve  21 A,  21 B open. Here, the volume can be limited to, for example, 45 liters/min at most. The branch point  18  therefore divides the water fed via the inlet  11  in each case into a separate spray water circuit  25 A for the one cutting drum and a separate spray water circuit  25 B for the other cutting drum  4 , wherein, depending on the ventilating direction or on account of other conditions, the flow rate of the spray water can be set differently via the spray circuits  25 A,  25 B. 
     The branch line  19  downstream of the branch point  18  opens into the cooling water circuit, which is designated overall by  30  and which may in turn comprise sub-circuits  30 A for the one cutting drum  4  and  30 B for the other cutting drum  4 . Each sub-circuit  30 A,  30 B can be provided with a plurality of cooling units, for example for cutting drum drive motors  31 , winch drive motors  32  for the respective direction of travel, driving motors  33  for the supporting arms and for other system components to be cooled  34 , such as pumps, etc. A volume regulating valve  35 , via which the respectively fed volume of cooling water can be set individually, can be assigned to every individual drive motor  31 ,  32 ,  33  or to every individual system component  34  to be cooled. The cooling water from the cooling water circuit  30 A can be fed via a return line  36 A and the cooling water of the cooling water circuit  30 B can be fed via a return line  36 B to a common return hose  41 , via which cooling water no longer required can be directed away from the longwall. Assigned to both return lines  36 A,  36 B is a respective control valve  37 A,  37 B which, via an intermediate line  39 A,  39 B protected by means of a check valve  38 , opens into one of the feed lines  23 A,  23 B to the cutting drums  4  in order to enable the cooling water to be fed from the respective cooling water circuit  30 A or  30 B to the associated cutting drum  4  as and when required. Therefore, by opening the control valves  37 A and  37 B, respectively, with valves  21 A,  21 B in the spray circuits  25 A,  25 B open, the volume of spray water fed to the respective cutting drums  4  can be increased by the volume of cooling water, or the spraying, by simultaneously closing the valves  21 A,  21 B, can be effected if need be solely with the cooling water used beforehand for the cooling. Metered feeding of spray water or cooling water to the cutting drums  4  can be achieved by suitable activation of the volume regulating valves and of the control valves. The additional water volume from the cooling water circuit  30 A or  30 B can be fed to the cutting drums  4  even when, for example, the pressure-difference measuring system  40  assigned to the respective cutting drums  4  indicate an increase in the differential pressure and thus clogging of the nozzles in the cutting drums  4 . 
     Furthermore, in the exemplary embodiment shown, the water circuit  10  comprises a camera cleaning system  50 , which can be actuated via a branch line  51  and a valve  52  in order to be able to clean, for example, the lenses of monitoring cameras, and a fire extinguishing spray system  60  having a plurality of nozzle groups  61  which are assigned to the cutting motors and the shearer loader body. The fire extinguishing system  60  is actuated manually via manual control valves  62  and a pilot-controlled valve  63 , and the extinguishing system  60  is connected directly to the water inlet  11  upstream of the reversible flow filter  12  via the branch line  64 . 
       FIG. 3  shows, in a second hydraulic plan, an alternative exemplary embodiment for the configuration of the water circuit for a combined spray and cooling system in a shearer loader according to  FIG. 1 . Of the shearer loader, only the two cutting drums  104  with the plurality of nozzles are shown in  FIG. 3 . The water is supplied to all the water circuits  110 , as in the previous exemplary embodiment, via a central water inlet  111 , of which a branch line  164  leads to a preferably manually actuable fire extinguishing system  160 , whereas the main volume of water here first flows to a flow-rate/water-pressure monitoring system  113  and then to a double reversible flow filter  112  and from there via a pressure regulating device  116  and a pressure limiting device  117 , as in the previous exemplary embodiment, to a main branch point  118 . As in the previous exemplary embodiment, the volume of water at the main branch point  118  is fed via a branch line  119  to a cooling water circuit which is designated overall by reference numeral  130  and which here again has two cooling water sub-circuits  130 A,  130 B. However, subgroups are in turn formed in each of the two sub-circuits  130 A and  130 B in order to feed the cooling water volumetric flow of the two cooling units  131 , e.g. drive motors, to a first control valve  137 A via a first return line  136 A and the cooling water volumetric flow of the units designated by reference numeral  132  to a second control valve  187 A via a return line  186 A. An identical construction is found in the second sub-circuit  1308  of the cooling water circuit having the control valve  137 B in the return line  136 B and the control valve  187 B in the return line  186 B. In the initial position, all the control valves  137 A,  137 B,  187 A,  187 B are operated in such a way that the water flows from the individual return lines  136 A,  136 B,  186 A,  186 B to the return hose  141  and can be conducted away from the shearer loader or the longwall. However, each individual control valve  137 A,  187 A,  137 B,  187 B can also be operated—if need be independently of all the other control valves and valves—in such a way that the respective water volumetric flow flows from the associated return line, e.g.  136 A at the control valve  137 A, not to the return hose  141  but rather to the feed line  123 A (or  123 B in the cooling water circuit  130 B) to one of the two cutting drums  104 . The inflow to the feed lines  123 A,  123 B is in this case effected downstream, i.e. downstream of the valves of the spray water circuits, via intermediate lines which are protected by means of check valves  138 . 
     In the exemplary embodiment shown, the spray water circuit is also divided into two separate spray water circuits, namely into the spray water circuit  125 A for the cutting drum  104  shown on the left in  FIG. 3  and into the spray water circuit  125 B for the cutting drum  104  shown on the right in  FIG. 3 . The volumetric flow is divided at the main branch point  118  via the branch lines  120 A and  120 B, respectively. In deviation from the first exemplary embodiment, two valves  121 A,  171  A which can be activated separately and have volume regulating valves  122 A,  172 A connected upstream are now arranged in the branch line  120 A for the spray water circuit  125 A, and two valves  121 B,  171 B having volume regulating valves  122 B,  1728  connected upstream are also arranged in the branch line  120 B for the spray water circuit  125 B, in order to be able to set the volume of spray water differently in each spray water circuit  125 A,  125 B by opening or closing one or both associated control valves  121 A,  171 A. The inflow from the cooling circuits is effected downstream, i.e. downstream of the valves  121 A,  121 B,  171 A,  171 B of the spray water circuits  125 A,  125 B, via the intermediate lines protected by means of check valves  138 . Since both the valves  121 A,  171 A and the control valves  137 A,  187 A can be operated independently of one another via a control device (not shown here), there are, in the exemplary embodiment according to  FIG. 3 , already various adjusting means for the volume of spray water for the cutting drum  104  in the left-hand sub-circuit  16  identified by “A” in each case. The same applies of course to the right-hand cutting drum  104  downstream of the spray water circuit  125 B and the cooling water sub-circuit  130 B. In the second exemplary embodiment, the spray water can originate solely or partly from the associated spray water circuit  125 A or  125 B, solely or partly from the cooling water circuit  130 A,  130 B or from both sub-circuits. The adjusting means for optimizing the spray water ultimately fed to the cutting drums  104  can be set even more precisely by the arrangement of further control valves or valves. Since the control valves of the cooling water circuit have a connection to the return line  141 , it can be ensured at the same time that water temporarily not required for spraying can be directed away from the shearer loader again and thus from the longwall. 
     For the person skilled in the art, numerous modifications which are to come within the scope of protection of the appended claims emerge from the above description. It goes without saying that the system can also work at other pressures and that there may also be additional volume regulating valves, for example, in the intermediate lines in order to be able to regulate the volume of spray water fed to the cutting drums in an even more optimum manner. The number of valves and control valves present in each circuit or sub-circuit may vary and separate control valves could also be provided, for example, for each line branch in the cooling water circuit, said control valves interacting with a single valve or even with more than two valves in the spray water circuit in order to be able to set, as and when required, the admission of water to the individual cutting drums by separate activation of the valves and control valves. 
     Further, while considerable emphasis has been placed on the preferred embodiments of the invention illustrated and described herein, it will be appreciated that other embodiments, and equivalences thereof, can be made and that many changes can be made in the preferred embodiments without departing from the principles of the invention. Furthermore, the embodiments described above can be combined to form yet other embodiments of the invention of this application. Accordingly, it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Summary:
A shearer loader for underground mining, the shear loader comprising a shearer loader body, at least one cutting drum fastened to a supporting arm joined to the loader body, a first drive motor for moving the shearer loader and a second drive motor for moving the cutting drums, a cooling water circuit for cooling the first and second drive motors, the cooling water circuit including an inlet and a return line, a spray system including at least one spray water circuit, the spray system including a feed line fluidly connecting a common water connection to the cutting drums, the spray system further including a valve in the feed line for switching the spray water circuits on and off, a control valve connected between the feed line of the spray water circuit and the return line of the cooling water circuit, the control valve allowing selective flow from the cooling water circuit to be directed to the cutting drums.