Abstract:
The present disclosure relates to a dump truck or to a truck, comprising a diesel electric traction drive and a cooling system, wherein two radiator fans and/or cooler blowers of the cooling system are hydraulically driven.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to German Patent Application No. 10 2014 008 477.9, entitled “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 procedure 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]    Previously, all auxiliary consumers of the vehicle have been electrically driven; thus, for example, all components for the operation of a cooling air-based cooling system of the work machine. The energy supply of the motorized components of the cooling system has previously been provided by the generator of the diesel electric drive. It is a disadvantage of this procedure that different voltage circuits have to be produced for the different auxiliary consumers. For this purpose, at least one further power electronics module is required in addition to the power electronics for the control of the electrical traction drive, the further power electronics providing a suitable DC voltage circuit for the feeding of any auxiliary consumers such as blower motors, etc. 
         [0006]    It is the object of the present disclosure to show an innovative concept for the energy supply of the auxiliary consumers of a mobile work machine of the category. 
         [0007]    This object is achieved by a mobile work machine having a diesel electric traction drive and a cooling system for the cooling of any system components. The required components for the provision of the cooling system will be termed auxiliary consumers in the following. 
         [0008]    In accordance with the present disclosure, at least the auxiliary consumers of the cooling system, i.e., at least two radiator fans and/or cooling blowers of the cooling system, which are configured as radial fans, are hydraulically driven. The radiator fans or cooling blowers accordingly each comprise hydraulic motors which are associated with them and which can be supplied by a hydraulic circuit having the required pressure. In accordance with the present disclosure, the radiator fans and/or cooler blowers are now no longer electrically supplied by the provided energy of the generator, but are instead hydraulically driven. 
         [0009]    The radiator fans serve the sucking in of the cooling air, while the cooling fans serve to control the cooling air flow within the flow passages. 
         [0010]    The present disclosure results in a simplification of the power electronics since previously necessary components of the power electronics for providing a separate DC voltage circuit for the supply of the electrical fan motors can be dispensed with. The manufacture and maintenance of the power electronics is simplified and less expensive. The hydraulic drive of the fan motors and/or blower motors is in contrast characterized by a higher stability and reliability, which proves to be a great advantage particularly with work machines in the form of dump trucks due to the extreme environmental conditions at the deployment site. In addition, an operation of the fan motors and/or blower motors can be ensured practically independently of the operating conditions of the internal combustion engine. 
         [0011]    In an example embodiment of the present disclosure, the generated electricity of the diesel electric traction drive serves only the feed of the one or more traction drive motors. The supply of all further auxiliary consumers, in particular each and every consumer of the cooling system, is implemented by the integration of one or more hydraulic circuits. 
         [0012]    The required hydraulic energy for feeding the hydraulic motors for the radiator fans or for the cooling blowers is provided by one or more hydraulic pumps. The drive of the hydraulic pumps advantageously takes place via at least one transfer case which can be flanged either directly to the internal combustion engine, for example via a belt connection, or alternately on the outgoing engine shaft at the internal combustion engine or at the incoming or outgoing side at the generator. It is important in this embodiment that the internal combustion engine drives the generator directly, in particular by a shaft passing through the transfer case, so that any transmission losses of the drive train between the internal combustion engine and the generator are very largely avoided. A defined portion of the engine torque is branched off via the transfer case to drive the hydraulic pumps. Alternatively, one or more hydraulic pumps can also be connected directly to the internal combustion engine via a belt connection. 
         [0013]    In an example embodiment of the present disclosure, the utilized hydraulic drive of the respectively associated radiator fan or cooling fan is operable at a fixed or variable speed. The setting of the required speed can in particular be set independently of the operating point of the internal combustion engine or of the generator. 
         [0014]    The respectively used radiator fan is a radial fan which is driven by at least one hydraulic motor. 
         [0015]    In an example embodiment of the present disclosure, one or more air guidance passages run in the direction of the one or more electric drives, i.e., in the direction of the electric motors of the driven vehicle axle, in particular, the rear axle, and/or in the direction of one or more components of the power electronics of the diesel electric drive, in particular frequency inverters, and/or to the generator of the diesel electric drive itself. Sufficient cooling air can be conveyed in the direction of the components to be cooled by means of one or more cooling fans within the air guidance passages so that a sufficient cooling is achieved. 
         [0016]    The radiator fans or the radial fans are in particular arranged, viewed in the direction of travel, behind an upper deck of the work machine and/or above or on the generator of the diesel electric drive. 
         [0017]    Further advantages and properties of the present disclosure will be explained in more detail with reference to an embodiment shown in the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0018]      FIG. 1  shows an example of the dump truck embodiment in accordance with the present disclosure. 
           [0019]      FIG. 2  shows further detail of the embodiment of  FIG. 1 . 
           [0020]      FIG. 3  shows further detail of the embodiment of  FIG. 1 . 
           [0021]      FIG. 4  shows further detail of the embodiment of  FIG. 1 . 
           [0022]      FIG. 5  shows a perspective detailed view of the vehicle frame of the dump truck in accordance with the present disclosure. 
           [0023]      FIG. 6  shows a sketched schematic representation of the hydraulic circuit for the energy supply of at least one fan of the cooling circuit. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    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. 
         [0025]    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 is bounded by the bumper  22  in the region of the vehicle  10  at the front in the direction of travel. A radiator 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 radiator 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 . 
         [0026]    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 front region of the vehicle frame  12  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 radiator module  24  is seated directly in front of the internal combustion engine  40  at the vehicle front. 
         [0027]    The internal combustion engine  40  drives the generator  60  mechanically to generate the required electrical energy for the electrical traction drives. Two AC motors  80 , which are integrated to the left and right in the rear axle  16 , serve as the traction drive. Power electronics  100  with the required power components such as, for example, frequency converters, etc. are available for the control or regulation of the electric motors  80  and of the generator  60 . 
         [0028]    An air cooling circuit inter alia serves the cooling of the generator  60 , of the power electronics  100  and of the electric motors  80 . The cooling air is sucked in by two radial fans  130  which are mounted, viewed in the direction of travel, behind the upper deck  26  above the generator  60  and are in particular arranged centrally in the transverse direction. The sucked-in air is supplied via air passages to the generator  60 , to the power electronics  100  and to the electric motors  80  and to the planetary gears of the driven rear axle  16 . The radial fans  130  are not fed electrically, but rather each comprise at least one hydraulic motor which is acted on by the required hydraulic pressure via a hydraulic circuit. 
         [0029]    For this purpose, one or more hydraulic pumps are driven as auxiliary consumers via the transfer case  50 . In the embodiment shown, a hydraulic pump  65  is additionally driven by the shaft passing through the generator  60 . 
         [0030]    A schematic representation of the hydraulic circuit can be seen from  FIG. 6 . The hydraulic pump  65  is driven mechanically, by way of example, via the transfer case  50 . It pumps the hydraulic oil from the hydraulic tank  32  to the hydraulic motor  120  which generates the rotary movement of the radial fan  130 . The hydraulic medium conveyed to the motor  120  is subsequently led back to the tank  32 . The hydraulic motor  120  is secured by the check valve  110 . 
         [0031]    The hydraulic pump  65  is designed as variable to control the blower speed so that the speed of the blower motor  120  can be set variably. An additional pump as well as a control valve can be connected upstream or downstream of the hydraulic pump  65 . 
         [0032]    Due to the use in accordance with the present disclosure of hydraulic motors as radiator fan motors, additional components of the power electronics  100  for the design of an electric circuit for the supply of electrical blower motors can be dispensed with. The power electronics  100  used thereby have a considerably simpler design. Furthermore, the speed of the blower motors  120  can be set independently of the operating point of the internal combustion engine  40  or of the generator  60 . 
         [0033]    In addition to the air cooling, a cooling liquid circuit, in particular a common cooling circuit for cooling the generator  60  and/or the power electronics  100  and/or the electric motors  80  and/or the transmission oil of the planetary gears can also be provided. Required hydraulic pumps are then likewise driven via the transfer case  50 . 
         [0034]    In one example, a method may comprise operating a dump truck having a diesel electric traction drive and a cooling system, wherein the cooling system includes a radiator blower with two radial fans each driven via a hydraulic motor. During vehicle operation, such as driving of the vehicle along the ground with the vehicle moving, the diesel engine drives the traction motor to generate electrical power via a generator to drive the traction motors, the traction motors driving wheels to propel the vehicle along the ground. Also during this same vehicle operation, the diesel engine also drives a hydraulic system to generate hydraulic pressure to drive the fans via the hydraulic motor. The fans may blow cooling air through the vehicle system, including cooling the engine and/or traction motors. The fans are not coupled to the electrical system nor do they utilize any electric power from the generator.