Abstract:
A system for reducing the air resistance of a truck, particularly an articulated vehicle, wherein the vehicle comprises a cargo space that is limited downward by a loading floor and in the height thereof by a roof wall spaced apart therefrom. The aim is to provide a system that minimizes the face area of the truck and thus the fuel consumption in dependence on the actual cargo space used. According to one embodiment, the roof wall is height-adjustable opposite the loading floor.

Description:
FIELD OF THE INVENTION 
     The invention relates to a system for reducing the air resistance of a truck, especially an articulated vehicle, wherein this comprises a cargo space that is bounded at the bottom by a loading floor and in its height by a roof wall spaced apart therefrom. 
     BACKGROUND OF THE INVENTION 
     Usually trucks are built with the largest possible cargo space. This generally means that the end surface is large, being in direct proportional relation to the air resistance, and hence the fuel consumption is high. On the other hand, the available cargo space is seldom utilized completely in practice, since oftentimes small freight units are transported or a free space is left on top of the cargo to provide sufficient freedom of movement when loading or unloading. 
     Accordingly, the problem on which the invention is based was to provide a system that minimizes the end surface of the truck and thus the fuel consumption in dependence on the cargo space actually utilized. 
     SUMMARY OF THE INVENTION 
     The problem is solved according to the invention with a system in which the roof wall is adjustable in height relative to the loading floor. This affords the advantage that the area of the end surface can be reduced by lowering the roof wall before starting the trip or during the trip, depending on the actually available cargo volume. For example, when the truck is not freighted or is only carrying low parcel units, it is possible to lower the roof wall to a level beneath the driver&#39;s cabin. 
     The height adjustment of the roof wall should occur in a plane preferably parallel to the originally adjusted orientation, basically parallel with the loading floor. Alternatively, the roof wall can also be oriented at a slant, in particular, descending toward the front. 
     Preferably, a height adjustment of the roof wall is possible by means of telescoping pillars. These can be coupled to each other at least in pairs with regard to their travel. The telescoping pillars should be arranged at the four corners of the cargo space for a uniform force bearing and for reasons of easy loading and unloading of cargo. 
     It has been found to be advantageous to outfit the pillars with a motorized drive unit. This enables an easy adjustment of the pillars for the driver: with one or more adequately dimensioned drive units, a simultaneous and thus fast lifting or lowering of the roof wall is possible. If several drive units are used it should be possible to actuate them via a common control unit. According to one particularly advantageous embodiment, the control unit is in remote control contact with an operating and display mechanism. 
     Advantageously, several motorized drive units are provided in the form of a spindle and/or a pneumatic cylinder and/or a rack. Alternatively or in addition, the motorized drive unit can also comprise a scissors linkage and/or a cable control. The aforementioned motorized drive units enable a continuous lateral repositioning of the pillars and thus a likewise continuous height adjustment of the roof wall. 
     Advantageously, the cargo space is bounded at the sides by height-adjustable side walls. These ensure an outwardly closed cargo space regardless of the position of retraction of the roof wall relative to the loading floor. A major benefit of the height-adjustable side walls is that, when the roof wall is lowered during driving operation, no excess material of the lateral side walls will hang down loosely from the truck and become damaged by flapping in the wind or endanger other traffic participants. The rear door should also be configured as a height-adjustable side wall. 
     When the side walls are of stable shape, these can be fashioned, e.g., as two-piece and overlapping in the vertical direction. 
     Alternatively, the height-adjustable side walls can also each be fashioned from a tarpaulin that can be rolled up about a horizontal axis. According to another embodiment, when the roof wall is lowered the tarpaulin can be laid in folds about a horizontal folding axis. The height-adjustable side walls should preferably be coupled to the motorized drive unit of the pillars. Instead of a tarpaulin, a roller shutter with several wall panels that are hinged together can be used. 
     According to an alternative embodiment, it is also possible to fashion the height-adjustable side walls from sliding or folding wall panels. They can be moved into or out from a magazine when the roof wall is being lowered or raised. Such a height adjustment of the lateral side walls is done advantageously without a special motorized drive unit provided for this. 
     The height adjustment can be set manually by the driver, preferably from the driver&#39;s cabin. 
     Preferably, the height adjustment comprises a preselector control unit in assignable stages, so that the driver at first inspects the cargo height in the cargo space. This can be facilitated, for example, by an optically readable measurement scale in the cargo space. Next, the driver enters the measurement value found in the preselector control unit, which sets in motion a movement of the roof wall and drives its in discrete steps to the next lower level. 
     Advantageously, however, instead of the visual determination of the cargo height, there is provided a cargo height recognition module, which recognizes the actual height of loading and automatically performs the height adjustment of the roof wall, if desired. This embodiment enables, in particular, a height adjustment remotely controlled from the driver&#39;s cabin, without the driver having to go inside the cargo space. 
     It has been found to be especially expedient for the cargo height recognition module to determine the height of loading by means of at least one laser and/or ultrasound sensor and/or infrared sensor. According to a first preferred embodiment, the laser and/or ultrasound sensor and/or infrared sensor are at the same time a transmitter and receiver and interact with reflectors arranged on the opposite side of the cargo space. Advantageously, two sender/receivers are arranged on the side wall next to the driver&#39;s cabin and two reflectors on the opposite side wall. An especially comprehensive surveying of the height of loading is accomplished when the signals emitted by the particular transmitter criss cross the cargo space. 
     In a second, especially preferred embodiment, the ultrasound sensor is configured as an ultrasound unit for 3D scanning of the cargo space. This involves a so-called three-dimensional scanner, which makes do without any additional reflectors. This embodiment minimizes the space requirement for the cargo height recognition module and at the same time lowers the risk of damage to the individual components by parts of the cargo during the loading and unloading process. 
     The height adjustment of the roof wall can also be done in dependence on the driving speed. If a control unit is used for the operation of the motorized drive units, this can communicate with the vehicle control unit, for example, and obtain a signal from the latter as to the driving speed. A height adjustment will then occur only when traveling on expressways or autobahns, where a reduction of the air resistance by a lowering of the roof wall is especially noticeable on account of the high speed of travel. 
     Advantageously, a spoiler is arranged on the roof of the truck, whose inclination can be adapted to the height of the roof wall. For this, the spoiler should also be outfitted with an adjustment motor. The adjustment motor according to an especially advantageous embodiment is connected to the control unit for the pillars of the roof wall and obtains a corresponding signal in dependence on its state of extension. This prevents the spoiler from being in an extended position when the roof wall has already been lowered and is situated, for example, in the wind shadow of the driver&#39;s cabin. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For better understanding, the invention will now be explained more closely by means of five figures. There are shown: 
         FIG. 1 : a schematic side view of an articulated vehicle at maximum height of the cargo space; 
         FIG. 2 : a view of the articulated vehicle of  FIG. 1  with roof wall lowered; 
         FIG. 3 : a top view of a trailer with a cargo height recognition module located inside according to a first embodiment; 
         FIG. 4 : a three-dimensional view of a trailer with a cargo height recognition module located inside according to a second embodiment; 
         FIG. 5   a : a partial longitudinal section along the plane A:A in  FIG. 3  with height-variable side walls made from folding wall panels; 
         FIG. 5   b : a partial longitudinal section along the plane A:A in  FIG. 3  with height-variable side walls made from a tarpaulin that can be folded for stowage; 
         FIG. 5   c : a partial longitudinal section along the plane A:A in  FIG. 3  with height-variable side walls made from roller shutters. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a truck  1 , comprising a tractor  1   a  and a trailer  1   b  that can be removably secured to it by a customary fifth wheel. The trailer  1   b  has a cargo space  2 , on whose loading floor  3  a total of four freight units  18  are placed. The freight units  18  are, for example, Euro pallets with piece goods located on them. 
     The cargo space  2  is surrounded on the sides by side walls  8   a ,  8   b ,  8   c ,  8   d  oriented perpendicular to the loading floor  3 , the side wall  8   d  in the schematic side views of  FIGS. 1 and 2  being configured as a rear door, and the side wall  8   b  has been left out for reasons of clarity. At the top, the cargo space  3  is closed by a roof wall  4  oriented parallel to it. 
     The roof wall  4  is supported relative to the loading floor  3  at the front and rear end of the trailer  1   b  by two pillars each  5   a ,  5   b ,  5   c ,  5   d . In the position depicted for the roof wall  4 , this towers above the driver&#39;s cabin  19  of the tractor  1   a  in the vertical direction, on the roof of which is arranged a spoiler  16  to reduce the air resistance. 
     The freight units  18  placed on the loading floor  3  only partly fill up the cargo space  2 , especially at the top, so that a lowering of the roof wall  4  according to the invention to the level sketched with broken line by the travel path h is possible. For this, the pillars  5   a ,  5   b ,  5   c ,  5   d  outfitted with a motorized drive unit  6  are retracted, using preferably a pneumatic cylinder  7  as the drive unit  6 . 
     After the adjustment of the roof wall  4  to a level corresponding to the actual freighting, the position of the spoiler  16  should also be adapted. This can be done, for example, with an adjustment motor  17  engaging with the spoiler  16 , advisedly carrying out the adjustment of the spoiler  16  and the roof wall  4  by a shared electronic control device, not shown here. 
     In  FIG. 2 , the roof wall  4  of the trailer  1   b  is reduced to a lower level corresponding to the height of the loaded freight units  18 . Its upper edge is detected by a cargo height recognition module  12 , which comprises in the area of the front pillars  5   a ,  5   b  (also see  FIG. 3 ) a combination transmitter/receiver  13  and in the rear area, near the pillars  5   c ,  5   d , a corresponding reflector  14 . After completion of the loading operation, the transmitter/receiver  13  emits a signal in the direction of the reflector  14 , which, if no freight units  18  block the beam path  20 , is reflected by it and detected by the transmitter/receiver  13 . Both the transmitter/receiver  13  and the reflector  14  should be arranged stationary to the roof wall  4 . A lowering of the roof wall  4  is then possible until the beam path  20  is interrupted by at least one freight unit  18  in the manner of a light barrier. 
     By lowering the roof wall  4  below the level of the driver&#39;s cabin  19 , there is a massive reduction in the air resistance. In this position of the roof wall  4 , the spoiler  16  can be used with the least possible inclination. 
       FIG. 3  shows in a top view the intersecting beam path  20  of two transmitter/receivers  13  and the two corresponding reflectors  14 . By arranging the interacting transmitter/receivers  13  and reflectors  14  on opposite sides of the trailer  1   b , an especially comprehensive monitoring of the cargo space  2  results. 
     An alternative embodiment of the cargo height recognition module  12  is shown in  FIG. 4 . Here, a 3D ultrasound unit  15  is located in the front side wall  8   a , at the end surface, which scans the cargo space  2  and thereby determines the loading height of any freight units  18 . This embodiment makes do without any additional reflectors  14 . Furthermore, it is possible to install the 3D ultrasound unit  15  stationary in the side wall  8   a , which further reduces the risk of damage or unintentional disturbance of the setting. 
     With the lowering of the roof wall  4  it is also advisable to adapt the height of the side walls  8   a ,  8   b ,  8   c ,  8   d  and thereby ensure a cargo space  2  constantly closed all around. In the following described  FIGS. 5   a ,  5   b ,  5   c , each time for reasons of better visibility the front side wall  8   a  at the end surface is depicted as being variably adjustable. The side walls  8   b ,  8   c ,  8   d  are likewise made height-adjustable in similar fashion. 
     According to the embodiment shown in  FIG. 5   a , the height adjustment of the side walls  8   a ,  8   b ,  8   c ,  8   d  occurs by horizontally oriented wall panels  11 , that are hinged together at their top and bottom lengthwise edge and come together like an accordion when the roof wall  4  is lowered. The side walls  8   a ,  8   b ,  8   c ,  8   d  here can be configured as elements of stable shape. 
       FIG. 5   b  shows a configuration for trucks  1  with a tarpaulin  10  covering the cargo space  2 . This has one or more folds  10   a  in the horizontal direction, running across the entire width of the particular side wall  8   a ,  8   b ,  8   c ,  8   d.    
     In  FIG. 5   c  one finds another embodiment in which the tarpaulin  10  or hinged wall panels  11  can be rolled up about a horizontal axis  9  and form a roller blind or a roller shutter. 
     LIST OF REFERENCE NUMBERS 
     
         
           1  truck 
           1   a  tractor 
           1   b  trailer 
           2  cargo space 
           3  loading floor 
           4  roof wall 
           5   a - d  pillars 
           6  motorized drive unit 
           7  pneumatic cylinder 
           8   a - d  side wall 
           9  horizontal axis 
           10  tarpaulin 
           10   a  tarpaulin fold 
           11  folding wall panels 
           12  cargo height recognition module 
           13  transmitter/receiver 
           14  reflectors 
           15  3D ultrasound unit 
           16  spoiler 
           17  spoiler adjustment motor 
           18  freight units 
           19  driver&#39;s cabin 
           20  beam path 
         h roof wall travel path