Abstract:
A construction machine according to the disclosure comprises a primary drive configured to generate waste heat and one or a plurality of machine components, the machine components being arranged in the area of the primary drive of the construction machine. At least one of the machine components is arranged in a housing including at least one flow passage through which ambient air is sucked using underpressure or which can have ambient air supplied thereto using overpressure so that an air current is created.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims foreign priority benefits under 35 U.S.C. §119(a)-(d) to European patent application number EP 12 007 422.4, filed Oct. 30, 2012, which is incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The disclosure relates to a construction machine with a drive and a machine component. 
     BACKGROUND 
     Arranging components of a construction machine in housings is known in practice. They are provided for protecting the respective component accommodated therein against environmental influences. Conventional housings protect their contents primarily against ingress of dust, dirt, water and other liquids or objects which may damage the content mechanically. EP 2 397 611 A1, JP 2007-063876 A, JP 2004-225429 A, JP 2004-351967 A, JP 2000-096609 A and JP 2003-013469 A are here cited exemplarily. All these references disclose housings for electric or electronic components for construction machines. US 2003/127137 A1 represents another example. This reference discloses a housing for hydraulic components of a snowplow. 
     In particular in the case of electronic and electric components, the housings are frequently arranged in the area of the operator&#39;s cab so that they can easily be accessed by the driver or operator. In some construction machines, e.g., in road finishers, the operator&#39;s cab is located close to the primary drive of the construction machine so that it may happen that the housing and the machine component accommodated therein are exposed to the waste heat of the primary drive. This may entail problems, especially in the case of heat sensitive machine components and high ambient temperatures on a construction site. 
     SUMMARY 
     Considering that construction machines are increasingly used in comparatively hot regions of the world and must withstand the environmental conditions prevailing there, it is therefore an object of the present invention to ensure trouble-free operation of the construction machine even at high ambient temperatures. 
     A construction machine according to the present disclosure is characterized in that at least one of the machine components arranged in the area of the primary drive is accommodated in a housing including at least one flow passage through which ambient air can be sucked using underpressure or which can have ambient air supplied thereto using overpressure so that an air current is created. In this way, heat is dissipated from the interior of the housing and the content of the housing is protected against overheating. An arrangement in the area of the primary drive within the meaning of the present disclosure is given when the machine component is positioned directly adjacent to the primary drive or located in an area in which it is influenced by the waste heat of the primary drive. The at least one machine component may be electric or electronic components, hydraulic components, tanks or arbitrary other components. Furthermore, the housing may be tightly closed or it may include units allowing easy opening on the part of the operator, such as one or a plurality of lids, flaps, doors or the like. The primary drive may e.g., be an internal combustion engine. 
     It may be of advantage when the pressure difference creating the air current is generated by a fan. The fan may be arranged directly in or at the flow passage or it may be arranged in a duct provided for supplying air to or for discharging it from the housing. The duct may e.g., be a tube or a hose. 
     It may be particularly advantageous when the pressure difference creating the air current is generated by a cooling device of the primary drive. In this way, an additional fan may possibly be dispensed with. 
     According to a preferred variant, the air current is variably adjustable, e.g., with respect to its flow rate. It can thus be adapted to the prevailing conditions according to requirements. This can be done manually through user inputs or automatically, e.g., on the basis of parameters measured by sensors. 
     It may be of advantage when the air current can be controlled depending on the temperature of the respective machine component accommodated in the housing or depending on the temperature of the primary drive. The temperature of the respective machine component as well as the temperature of the primary drive may here also be used simultaneously in a closed loop control process. This will facilitate the work of the operating staff and also ensure at any time that the temperature of the machine component does not increase to undesirable values. 
     In addition, it is conceivable that cooling fins extend from a wall of the flow passage into the flow passage. Heat transport from the component into the flow passage could thus be further improved. In addition, the air current flowing through the flow passage can thus be deflected in a targeted way, if necessary. 
     It may also be expedient when a heat exchanger, which conducts heat from the internal space of the housing, is arranged in the flow passage. In this way, components requiring particularly intensive cooling could also be protected against overheating. In addition, a heat pump may be provided, if necessary. 
     According to a further advantageous variant, the flow passage is shaped such that when air flows therethrough a turbulent or a laminar air current will be created. This can have a positive influence on heat transport as well or on other factors, e.g., noise development or the air pressure that builds up in the space in question. 
     It may be particularly advantageous when an air inlet and an air outlet are arranged on opposite sides of the flow passage and/or of the housing, respectively. This ensures that the air current flows across the largest possible area of the inner wall of the flow passage, whereby improved heat exchange is accomplished. An equivalent result can also be achieved by a juxtaposed arrangement of the air inlet and the air outlet by extending the path along which the air current flows between air inlet and air outlet using a long flow passage. 
     It is conceivable that the flow passage is configured as a double wall. This is particularly advantageous when those wall elements of the housing that face the primary drive are configured as a double wall. In this way, the waste heat of the primary drive does not even arrive at the internal space of the housing. Additional protection against overheating is thus obtained for the components in the housing. 
     It may also be expedient when the thermal conductivity of an inner wall of the housing is higher than the thermal conductivity of an outer wall. This improves heat transport from the internal space of the housing into the flow passage defined by the double wall, while the transport of heat from outside into the same flow passage is reduced. In this way it is ensured that the highest possible percentage of the heat dissipated by the air current is removed from the machine component accommodated in the housing. This can be accomplished by various measures. For example, different materials with different thermal conductivities may be provided for the inner wall and the outer wall. Furthermore, different wall thicknesses, various kinds of heat insulation, multilayered walls and the like are conceivable. 
     In addition, it may be of advantage when only the wall elements facing the primary drive are configured as double-walled elements. If the space available is restricted, installation space can be saved in this way. 
     According to a further advantageous variant, all the wall elements of the housing may be configured as double-walled elements. The machine component accommodated in the housing is thus protected against thermal loads from all sides. 
     It may be particularly advantageous when the housing is thermally decoupled at its fastening units e.g., from a machine frame or an engine case. Thermal bridges counteracting the cooling effect can be eliminated in this way. 
     The construction machine is preferably a road finisher or a feeder. 
     In the following, an advantageous embodiment of the disclosure will be explained in more detail with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective view of a construction machine, which is a road finisher in the case of this example. The disclosure may, however, also be some other construction machine; 
         FIG. 2  shows in a schematic view the primary drive of the construction machine shown in  FIG. 1 , a cooling device of the primary drive as well as a housing for accommodating a machine component; 
         FIG. 3  shows a schematic sectional view of a housing for a machine component according to an embodiment of the present disclosure; 
         FIG. 4  shows a schematic sectional view of a housing for accommodating a machine component according to a further embodiment of the present disclosure; 
         FIG. 5  shows a schematic sectional view of a housing for a machine component according to a further embodiment of the present disclosure; and 
         FIG. 6  shows a schematic sectional view of a housing for a machine component according to a further embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a construction machine  1 , in this case a road finisher, including a primary drive  2  positioned here behind a body part provided with cooling slots. Above the primary drive  2 , an operator&#39;s cab  3  is arranged, the bottom of this operator&#39;s cab  3  having embedded therein a machine component  4 . This place of installation is representative of all the places of installation of machine components which are located in the area of the primary drive, i.e., which are exposed to waste heat of the primary drive. 
       FIG. 2  schematically shows how the primary drive  2  of the construction machine  1 , a cooling device  5  of the primary drive  2  as well as a housing  6  for accommodating a machine component  7  are arranged relative to one another. The machine component  7  may be one or a plurality of electric or electronic components, hydraulic components, a tank or arbitrary other components. In the present embodiment, the cooling device  5  is arranged directly adjacent to the primary drive  2 . It may, however, also be arranged further away from the primary drive  2  and connected thereto through cooling ducts  8 . The housing  6  and the machine component  7  accommodated therein are arranged in the area of the primary drive  2 , which is frequently implemented as an internal combustion engine. This means that they are located either directly adjacent to the primary drive  2  or in an area in which they are influenced by the waste heat of the primary drive  2 . The cooling device  5  and the housing  6  are interconnected by a hose  9 . Alternatively to a hose, a tube or some arbitrary other duct element may also be used. 
     The housing  6  is composed of various wall elements. Wall element  10  is located on the housing side facing the primary drive  2  and wall element  11  is located on the housing side facing away from the primary drive  2 . The housing  6  has provided thereon an air inlet  12  through which air can be sucked in either directly or through additional duct elements (not shown). The pressure difference required therefor is generated by the cooling device  5  in the embodiment shown. A fan or an arbitrary other unit may, however, be used for this purpose as well. 
       FIG. 3  is a sectional view of the housing  6  according to a first embodiment of the construction machine  1 . The wall elements  10  facing the primary drive  2  are configured as double-walled elements, i.e., they comprise an outer wall  13  as well as an inner wall  14 . The inner wall  14  defines an internal space  15  that accommodates the machine component  7 . A flow passage  16  is defined by the inner wall  14  and the outer wall  13 . In the present embodiment, the wall elements  11  facing away from the primary drive are configured such that they comprise only one wall. 
     Through the air inlet  12 , ambient air is sucked-in in an air current S. The air current S flows through the flow passage  16 , past the inner wall  14 , where it takes up heat, and leaves the flow passage  16  through the air outlet  17 . In this embodiment, the air inlet  12  and the air outlet  17  are arranged on the outer wall  13  at the maximum possible distance from one another. This ensures that the air current S will flow across the largest possible area of the inner wall  14 . 
       FIG. 4  shows the housing  6  according to a further embodiment of the present disclosure. The air inlet  12  and the air outlet  17  are here arranged directly adjacent to one another. A dividing wall  18  ensures that the air current S will not take the shortest route from the air inlet  12  to the air outlet  17 , but will flow through the entire flow passage  16  and, in so doing, take up the maximum possible amount of heat from the inner wall  14 , and leave the flow passage  16  then through the air outlet  17 . In addition, all wall elements  10 ,  11  are configured as double-walled elements in this embodiment. 
     In the embodiment shown in  FIG. 5 , all wall elements  10 ,  11  are configured as double-walled elements as well. A dividing wall  18  is not provided here. Instead, the air inlet  12  and the air outlet  17  are arranged on opposite sides of the housing  6  and/or the flow passage  16 , respectively. Thus, it is again ensured that the air current S will flow across the largest possible area of the inner wall  14 . In this embodiment, a fan  19  is provided for generating the pressure difference required for the air current S. A fan  19  may be used in all the embodiments. 
     According to a further variant, the air current S may be variably adjustable. This can be done manually or automatically. In the event that the pressure difference required for the air current S is generated by a fan  19 , the adjustment of the air current can be accomplished by adapting the rotational speed of the fan  19 . Alternatively, controllable valves may be used. The latter would be the preferred variant for enabling adjustability, when the underpressure required for the air current S is exclusively generated by the cooling device  5  of the primary drive  2 . Just as the fan, such control valves may be provided at an arbitrary location at which the air current S flows through, e.g., the flow passage  16 , the air inlet  12 , the air outlet  17 , the duct element  9  or a further duct element that may possibly be connected to the air inlet  12 . The control of the fan speed or of the valve opening times (duty cycle) may be automatically controllable according to a further variant. Input parameters may here be the temperature of the machine component  7 , the temperature of the primary drive  2  or both said values. 
     A further modification may be so conceived that cooling fins  20  extend from the inner wall  14  into the flow passage  16 . This would improve heat dissipation from the internal space  15  on the one hand and the air current S could be influenced in a targeted way by such cooling fins on the other. 
     According to a further variant, a heat exchanger  21  can be provided in the flow passage  16 , as can be seen from  FIG. 6 , the heat exchanger  21  transporting with the aid of a medium heat from the internal space  15  into the flow passage  16 . Such a variant may also include a heat pump  22  for machine components  7  requiring particularly intensive cooling. 
     According to a further modification, the flow passage  16  may be shaped such that a turbulent or a laminar air current S is formed. In this way, the transport of heat as well as other factors, such as noise development or the pressure in the flow passage  16 , could be influenced. 
     A further variant is so conceived that the thermal conductivity of the inner wall  14  can be higher than the thermal conductivity of the outer wall  13 . This would ensure that the smallest possible amount of heat is transferred from the primary drive into the flow passage  16 , whereas the highest possible amount of heat is dissipated from the internal space  15  of the housing into the flow passage  16 . For example, different materials having different thermal conductivities may be provided for the respective inner and outer walls. In addition, different wall thicknesses, various kinds of thermal insulation, multilayered walls or the like are conceivable. 
     Furthermore, the housing  6  may, according to a further variant, be thermally decoupled at fastening units  23  by which the housing  6  is fastened to or in the construction machine  1 , as can be seen from  FIG. 6 . Undesired thermal bridges would be avoided in this way. 
     The embodiments described show the flow passage  16  as a double wall. It may, however, also extend in an arbitrary way or form through or in the internal space  15  of the housing  6 . For example, a flow path having the greatest possible length and reaching the highest possible number of areas of the internal space may be provided. In addition, a helical or wavelike shape of the flow passage  16  is conceivable. The flow passage  16  may additionally have openings at various points, the openings allowing the cooling ambient air to flow directly across the machine component  7  or parts thereof. 
     The flow passage  16  may have any suitable cross-section, it may e.g., be circular, elliptical, square or rectangular. 
     According to a preferred variant, the construction machine  1  may be a road finisher or feeder. 
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.