Abstract:
The present disclosure relates to a mobile work machine, in particular in the form of a dump truck or truck, comprising a diesel electric traction drive and a cooling system, wherein a common cooling circuit of the liquid cooling medium is provided for the parallel cooling of one or more components of the power electronics and for the cooling of one or more drive components in the region of the driven vehicle axle.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to German Patent Application No. 10 2014 008 345.4, entitled “Work Machine, in Particular Dump Truck or Truck” filed on Jun. 5, 2014, the entire contents of which is hereby incorporated by reference in its entirety for all purposes. 
       TECHNICAL FIELD 
       [0002]    The present disclosure relates to a mobile work machine, in particular in the form of a dump truck or of a truck, comprising a diesel electric traction drive and a cooling system. 
       BACKGROUND AND SUMMARY 
       [0003]    Dump trucks or so-called large dump trucks are predominantly used in coal mining operations or ore mining operations for the transport of the mined coal, minerals and ores. These bulk material dumpers are manufactured in sizes of more than 90 metric tons (t) up to several 100 t in weight and payload so that they have very large dimensions overall. 
         [0004]    A diesel electric drive is used as the traction drive, wherein the mechanical energy generated by a diesel engine is converted with the aid of a generator into electrical energy for the supply of the electric traction drives. The reason for this process is that diesel engines, like all internal combustion engines, can only be operated with ideal efficiency in a very restricted speed range and cannot be started under load. The AC motors for the driving axle which are used can also produce the desired torque in the lower speed range for starting. The internal combustion engine used can be operated continuously in the ideal speed range. 
         [0005]    Various components of the fraction drive requiring cooling were previously cooled by means of separate cooling systems, which results in a not insubstantial effort in the production of such dump trucks caused by the construction. 
         [0006]    To make matters worse, the cooler inlet of the mobile work machine is typically seated in the region of the vehicle front, but the components to be cooled in the diesel electric drives used are rather arranged in the rear region. The transmission oil to be cooled is currently conducted from the vehicle rear in the direction of the heat exchangers mounted at the vehicle front to utilize the cooling effect of the air stream. This would mean that hot oil is disadvantageously conducted past the combustion engine, whereby a huge risk of fire results. 
         [0007]    It is the object of the present disclosure to provide an improved cooling system of a mobile work machine of the category. 
         [0008]    This object is achieved by a mobile work machine, in particular by a dump truck or by a truck, having a common cooling circuit comprising a liquid cooling medium for the parallel cooling of one or more components of the power electronics of the diesel electric drive and for the cooling of one or more drive components in the region of the driven vehicle axle. The required circulation path of the liquid cooling medium is reduced to a minimum by the use of a common cooling circuit. An effective cooling effect can be achieved by the shortened flow paths. At the same time, the total complexity of the work machine is reduced since no separate cooling systems have to be provided and serviced. 
         [0009]    Water or glycol can be considered as the used cooling medium, for example. 
         [0010]    The one or more components of the driven vehicle axle to be driven are, for example, one or more electrical drive motors of the diesel electric drive which, for example, drive the tires of the driven axle in pairs. The rear axle is typically the driven axle of the mobile work machine. 
         [0011]    It is conceivable that the electrical drive motors drive their associated axial section or the wheel hubs of the driven vehicle axle in a speed transformed manner via suitable transmissions  75 . The transmission oil used can likewise be coolable by the common cooling circuit. One or more planetary transmissions which are each integrated into the wheel hubs and which transfer the output moment of the electric motors to the wheel axle or wheel hub are frequently used as such transmissions. 
         [0012]    The cooling of the transmission oil can be realized by means of one or more oil coolant heat exchangers. The required heat exchangers are, for example, arranged close to the transmission to keep the line path of the transmission oil as short as possible. An arrangement is conceivable in the region of the driven vehicle axle or in the region between the driven axle and the power electronics or, optionally, in the region between the generator and the power electronics. Cooling liquid of the common cooling circuit thus flows through the electric motors used, on the one hand, and through the one or more transmissions, in particular planetary transmissions, i.e. the heat exchangers used, on the other hand. 
         [0013]    The advantageous arrangement of the heat exchangers makes a supply of the hot transmission oil from the driven rear axle up to the front region of the vehicle superfluous; the risk that the conveyed oil ignites is reduced. 
         [0014]    One or more of the components of the power electronics to be cooled are, for example, one or more frequency converters for controlling the one or more electric motors of the driven vehicle axle. The generator of the diesel electric drive used is also understood as a component to be cooled in this connection. The one or more components of the power electronics are flowed through by the cooling liquid of the common cooling circuit in a known manner and are effectively cooled down. 
         [0015]    The circulation may take place within the coolant circuit such that components having a higher cooling requirement are cooled or flowed through with priority, whereas components having a smaller cooling requirement are arranged downstream in the cooling circuit. The components of the power electronics, for example, have to be cooled down a lot more or require a lower temperature of the coolant since the regular operating temperature of the component is lower. 
         [0016]    The transmission oil used of the one or more transmissions to be cooled is, in contrast, less demanding and less in need of cooling so that the temperature of the coolant can be higher for a sufficient cooling. It is proposed for this reason in accordance with an advantageous embodiment of the present disclosure that the cooling medium of the common cooling circuit first cools or flows through those components of the power electronics, such as the frequency converters, and/or the electric motors of the driven axle and is supplied subordinately to the one or more heat exchangers for cooling the transmission oil of the transmission types used in the driven vehicle axle. 
         [0017]    The common coolant circuit is optionally configured such that at least some of the components to be cooled having similar cooling demands are cooled or flowed through in parallel. Provision can be made, for example, that the components of the power electronics and/or at least one of the electric drive motors is/are cooled or flowed through in parallel by the cooling medium of the common cooling circuit, whereas the one or more transmissions of the driven vehicle axle are cooled or flowed through subordinately. 
         [0018]    In an example embodiment of the present disclosure, the cooling medium is conducted through a liquid cooler arranged as a heat sink in the front region of the work machine and is led from there via one or more pumps in the direction of the components to be cooled in the rear region. 
         [0019]    Further advantages and properties of the present disclosure result from the embodiment shown in the Figures. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0020]      FIG. 1  shows a representation of the dump truck in accordance with the present disclosure. 
           [0021]      FIG. 2  shows another representation of the dump truck of  FIG. 1 . 
           [0022]      FIG. 3  shows another representation of the dump truck of  FIG. 1 . 
           [0023]      FIG. 4  shows another representation of the dump truck of  FIG. 1 . 
           [0024]      FIG. 5  shows a perspective detailed view, drawing approximately to scale (although other relative dimensions may be used if desired) of the vehicle frame of the dump truck of  FIG. 1 . 
           [0025]      FIG. 6  shows a sketch-like circuit diagram illustration of the coolant circuit of the dump truck in of  FIG. 1 . 
           [0026]      FIG. 7  shows an illustration of the vehicle drive system in accordance with the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    A dump truck  10  is shown in  FIGS. 1 to 4 . It is here a so-called large dump truck such as is used in ore mines. Front wheels  14  and rear wheels  16 , driven via electric motors not shown in more detail, are supported at a rigid frame  12 . The rear wheels  16  are designed with dual tires. The truck is shown on level ground  101  with vertical being as illustrated with respect to gravity and the horizontal level ground on which the vehicle is positioned. A forward direction is shown to the left of  FIG. 1 , with rearward being opposite of forward. 
         [0028]    A skip  18  is pivotally connected to the frame  12  and is pivotable via hydraulic lifting cylinders  20  provided at both sides at the vehicle. The vehicle  10  is bounded by the bumper  22  in the region of the vehicle  10  at the front in the direction of travel. A cooler module  24  is arranged above the bumper  22 . An upper deck  26  on which an operator&#39;s cabin  28  is arranged in turn extends over the width of the dump truck  10  above the cooler module  24 . In the embodiment shown here, the operator&#39;s cabin  28  is positioned at the side of the upper deck  26  at the left in the direction of travel. The operator&#39;s cabin thus lies above the front left wheel  14 . 
         [0029]    The dump truck  10  comprises a dielectric drive which is easily recognizable in the perspective detailed view of the vehicle frame  12  in  FIG. 5 . The drive comprises the diesel engine  40  which is mounted in the vehicle frame  12  in the front region viewed in the direction of travel. The internal combustion engine  40  is in particular seated in the region of the front axle  14  beneath the upper deck  26  and the operator&#39;s cabin  28 . The cooler module  24  is seated directly in front of the internal combustion engine  40  at the vehicle front  30 . 
         [0030]    The internal combustion engine  40  drives the generator  60  mechanically to generate the required electrical energy for the electrical traction drives  80 . Two AC motors  80 , which are integrated to the left and right in the rear wheel axle  16  and sharing a common axle and motor axis  81 , serve as the traction drive. Power electronics  100  with the required power components such as frequency converters, etc. are available for the control or regulation of the electric motors  80  and of the generator  60 . 
         [0031]    The two electric motors  80  drive the left and right wheel hubs of the driven rear axle  16  independently of one another. The drive takes place via a planetary transmission not shown in  FIG. 5 . Each electric motor  80  is connected to the wheel hub of the driven rear wheel axle  16  via a planetary transmission. 
         [0032]    Both the power electronics  100  and the oil used of the planetary transmission have to be cooled during the operation of the dump truck  10 . The new coolant circuit in accordance with the present disclosure is used for this purpose. The coolant circuit uses a liquid cooling medium, for example water or glycol, which is cooled down accordingly by the cooler module  24  as a heat sink. The cooling medium is conveyed via the cooling lines by means of one or more hydraulic pumps  65  into the rear part of the vehicle frame  12 . 
         [0033]    The one or more hydraulic pumps  65  are served by a power takeoff of the pump transfer case  50  which is seated directly at the generator output in the embodiment shown. The pump transfer case  50  at which the hydraulic pumps  65  are arranged is integrated into the cooling circuit. The transfer case  50  can, however, alternatively be arranged directly at the internal combustion engine  40  or at the generator  60  or between the generator  60  and the internal combustion engine  40 . 
         [0034]    The pump  65  conveys the hydraulic medium from the front side of the dump truck  10  in the direction of the power electronics  100  so that these components, in particular the frequency converters, are cooled or flowed through by the conveyed cooling medium and are cooled down to the desired operating temperature level. In addition, the coolant is supplied to the one or more water-oil heat exchangers  90 , optionally one heat exchanger per planetary transmission, mounted in the region in front of the power electronics  100  viewed from the vehicle front  30  to cool the transmission oil used of the planetary transmissions in the driven rear wheel axle  16 . For this purpose, the oil is conducted from the rear wheel axle  16  up to the heat exchangers  90 . The coolant can furthermore be supplied to the electric motors  80  downstream of the transmission oil coolers. 
         [0035]    The present disclosure discloses a single cooling circuit for the named components which extends from the front side of the vehicle frame  12  up to the vehicle rear. The circulation of the cooling medium is restricted to the frame region, with the short line paths allowing an effective cooling. The pressure compensation vessel  70  is additionally provided to compensate the temperature fluctuations of the cooling medium. 
         [0036]      FIG. 6  shows a sketched illustration of the cooling circuit. The cooling medium used is conveyed from the cooling module  24  as a heat sink via the pump  65  in the direction of the power electronics  100  and of the heat exchangers  90 . Since the frequency converters of the power electronics  100  require a lower temperature level for operation, less than 65° here, the medium cooled down by the cooling module  24  (temperature less than 55°) is primarily conveyed to these components  100 . 
         [0037]    After flowing through these heat sources, the cooling medium now has a higher temperature in the range of 65° which is sufficient for the cooling of the transmission oil. The heat exchangers  90  are consequently connected downstream of the power electronics  100  in the circulation flow of the cooling medium. The heat exchangers  90  are likewise flowed through in parallel with one another. 
         [0038]    The design in accordance with the present disclosure allows a common cooling circuit for the components to be cooled so that the number of cooling circuit components, etc. is reduced and a sufficiently effective cooling is nevertheless provided. 
         [0039]    In one example, being in the region of a component may include within the component and/or adjacent to the component, and/or within a threshold distance of the component such as within an outer envelope defined by the component, and/or as specified above herein and/or as specified in the figures. 
         [0040]      FIG. 7  shows engine  40  mechanically driving generator  60 , which as noted above may have a power take off  50  to drive pump  65 . Electrical output from generator  60  is provided to power electronics  100  for conditioning and control of current and electrical power supplied to traction drive motor  80 . Mechanical power generated by motor  80  is fed through transmission  75  to axle  16 , and then to vehicle wheels to dive the vehicle, as described above herein.