Abstract:
Apparatus attached to the rear of a large box like vehicle for reducing rear drag, resulting from the movement of the vehicle includes an aerodynamically shaped structure rotatably mounted along at least one of the rear edges of said vehicle. The structure defines an enclosed space facing the rear of the vehicle which extends beyond the rear edges of the vehicle thereby increasing the length of the body of the vehicle and at the same time increasing the storage capacity of the vehicle. In one embodiment the structure includes two doors rotatably mounted along the vertical edges of the rear of the vehicle. The two doors, when closed, form an aerodynamic drag reducer. When access to the rear cargo doors is required the drag reducing doors are unlocked and/or unlatched and swung open to the sides of the vehicle.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to apparatus for reducing the drag associated with box-like vehicles when in motion. 
         [0002]    It is known that the box like configuration of the rear of vehicles such as trucks and trailers results in the creation of “drag” which is particularly noticeable at higher speeds. Drag present at the rear of a vehicle is basically the result of reduced air pressure created at the rear of the vehicle and becomes more pronounced as the vehicle is operated at higher speeds. Drag causes an increase in fuel consumption. It decreases the efficiency of the vehicle and increases the cost of operation. To reduce drag the attachment of various aerodynamic structures to the rear of a vehicle have been proposed. For example, U.S. Pat. Nos. 4,142,755, 4,257,641 and 4,741,569 are cited as some of the many attempts to deal with this problem 
         [0003]    However, known suggestions to deal with the rear drag of a vehicle have proven to be impractical and/or cumbersome. In particular, none of the known solutions provide an easy access to a vehicle&#39;s rear cargo doors. 
         [0004]    It is an object of the invention to provide a structure which can be attached to the rear of a vehicle for reducing the vehicle&#39;s drag while enabling easy access to the vehicle&#39;s cargo or cargo doors. 
       SUMMARY OF THE INVENTION 
       [0005]    Apparatus embodying the invention includes an aerodynamically shaped structure which can be attached to the rear of a box like vehicle in a manner which allows easy access to the cargo and/or the cargo doors. The aerodynamic shape of the structure ensures that the drag exhibited by, and on, the vehicle is substantially reduced. The aerodynamically shaped structure may be in the form of double doors rotatably mounted about opposite edges of the rear of the vehicle, or in the form of a single door which is rotatably mounted about one of the edges of the rear of the vehicle. The aerodynamically shaped structure increases the length of the vehicle. But, in accordance with the invention the additional length is used to provide additional storage space. Structures embodying the invention may be mounted on vehicles already having cargo doors to provide drag reduction while also providing additional storage capacity and be operable to enable easy access to the cargo via the pre-existing cargo doors. That is, the door or doors of a structure embodying the invention may first be opened to gain access to preexisting cargo doors, which then have to be opened. Alternatively, the structures embodying the invention may be used exclusively as the cargo doors of new vehicles or retrofitted to be the only cargo doors of previously built vehicles, thereby eliminating the need for another set of cargo doors. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    In the accompanying drawings like reference characters denote like components; and 
           [0007]      FIG. 1  is an isometric view of doors embodying the invention mounted on the rear of a truck in accordance with the invention; 
           [0008]      FIG. 1A  is a top view of two triangularly shaped doors formed and mounted in accordance with the invention; 
           [0009]      FIG. 1B  is a top view of two curved doors formed and mounted in accordance with the invention; 
           [0010]      FIG. 2  is a view of the doors shown in  FIG. 1 , in the open position; 
           [0011]      FIG. 3  is an isometric view of doors formed in accordance with the invention and mounted on the rear of a truck having existing vertical cargo doors; 
           [0012]      FIG. 4  is a drawing of doors suitable for use in the embodiment shown in  FIG. 3 , with the doors shown in the open position. 
           [0013]      FIG. 5  is an isometric drawing of a wedge shaped drag reducing door formed in accordance with the invention; 
           [0014]      FIG. 6  is a drawing of a side view of  FIG. 5  showing a door formed in accordance with the invention having sloped top and bottom surfaces; 
           [0015]      FIG. 7  is an isometric diagram of a door embodying the invention having a curved aerodynamic surface; 
           [0016]      FIG. 8  is a top view of the door shown in  FIG. 7 ; 
           [0017]      FIG. 9  is a side view of a door formed in accordance with the invention having sloped top and bottom surfaces; 
           [0018]      FIG. 10  is a view looking out from inside the truck showing the enclosed additional storage space formed by a structure embodying the invention; 
           [0019]      FIG. 11  is a diagram of a single triangular door formed to provide drag reduction and additional storage space in accordance with the invention; and 
           [0020]      FIG. 12  is a diagram of a single semi-circular (bowed) door formed to provide drag reduction and additional storage space in accordance with the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]      FIG. 1  shows two drag reducing doors A and B mounted on the rear of a truck  2 , in the closed, drag reducing, position.  FIG. 2 , shows the doors in the open position. The doors A and B are mounted by means of hinges  9  located at, and along, the outer, vertical, edges of the truck. In the closed position, the side walls  16   a ,  16   b  of the two doors face each other along a line (and plane) which corresponds generally to the center of the truck&#39;s rear. The outer walls  5  ( 5   a ,  5   b ) of the doors are shaped to provide aerodynamic air flow and decreased turbulence and drag. Some possible shapes are shown and discussed herein. However, it should be understand that this is by way of example only and that the doors may have numerous different shapes to provide improved aerodynamic air flow. 
         [0022]    By way of illustration, reference may be had to  FIGS. 1 ,  1 A,  2 ,  5 ,  6 , and  10  which show that the doors may have a wedge-like, or triangular, configuration extending rearwardly beyond the rectangular rear wall edges of truck  2 .  FIG. 1A  shows a top view of the doors of  FIG. 1 . Each one of the two doors has two solid sides or walls extending between solid upper and bottom sides to produce an open space (pocket) within the interior of the door while the exterior of the door is aerodynamically shaped to decrease turbulence and drag. In  FIG. 1A , the outer door panels  5   a ,  5   b , extend at a fixed angle from their respective mounting edges such that the thickness of the doors increases as their distance increases from their mounting edge; their thickness being maximum at the center of the rear of the truck  2 , where their facing sides  16   a ,  16   b  abut each other. When closed the internal storage space existing within the doors face the cargo doors (if present) or the rear of the truck if there are no cargo doors. A latch  11  is provided to lock the doors. This latch may be any mechanism for securely holding the two doors together, but which can be easily opened or closed. 
         [0023]    It should be appreciated that, in accordance with the invention, the exterior and side walls of doors A and B are made to provide an open space within the (triangular) extension which may be used as additional cargo space. The additional cargo space may include shelves as shown in  FIG. 10 . Alternatively, the space within the triangular extension may be left undefined to allow the contents of the main cargo space of truck  2  to extend within the triangular extension. Thus, the aerodynamically shaped doors embodying the invention reduce drag, thereby increasing the operating efficiency of the vehicle while providing additional storage space. 
         [0024]    The embodiment of  FIGS. 1 and 2  may be used with existing trucks having a pre-existing roll up cargo door. That is, existing trucks with roll up doors may be retrofitted with doors embodying the invention. Alternatively, cargo doors of existing trucks which do not provide drag reduction may be removed and replaced by doors embodying the invention. Still further, it is anticipated that new trucks may be manufactured with doors embodying the invention. 
         [0025]      FIG. 2  is a top view illustrating the drag reducing doors A and B in the open position. Note that the doors are rotated about hinges  9 . The mounting of the drag reducing doors with hinges along the rear vertical edges of the truck is suitable for a truck with roll-up cargo doors. When in the closed position, doors A and B form a drag reducing structure having a vertical outer edge  18 . In the closed position the inner door sides  16  ( 16   a ,  16   b ) face each other. The sides may be provided with a resilient type gasket material for an airtight seal. The resilient gasket material may also be provided along the edges of plane  13  (see edges  13   bu ,  13   bl ,  13   bi  and  13   bo  in  FIG. 10 ) and the rear edges of the rectangular outer walls of truck  2 . 
         [0026]      FIGS. 5 ,  6  and  10  are more detailed views of triangularly shaped doors suitable for forming the double doors embodying the invention. An examination of these figures shows that, in one embodiment, each one of the double doors may be generally wedge shaped and include two solid side walls ( 5  and  16 ) and two solid top and bottom wall panels  71  and  81 . Wall  5  is the outer panel/wall of door A or B. Sidewalls  16  ( 16   a  or  16   b ) extending in a generally perpendicular direction from an internal edge  13   i  to outer edge  18  of outer wall  5 . The width of the sidewall  16  may range from a few inches to more than one half the width of the rear of the vehicle. Upper door panel/wall  71  defines a plane extending horizontally from walls  5  and  16  to the top of horizontal inner edge  13   u . Bottom door panel/wall  81  defines a plane extending horizontally from walls  5  and  16  to the bottom horizontal inner edge  13   l.    
         [0027]      FIG. 6  illustrates that the upper panel  71  may slope down and that bottom panel  81  may slope up to reduce turbulence and drag exhibited by the vehicle when operated at high speeds. 
         [0028]      FIG. 1B  shows a top view of doors A and B whose exterior portions  51   a ,  51   b  have a generally concave shape. In  FIG. 1B , the outer door portions  51   a ,  51   b , curve (or bow) out such that the thickness of the doors is the least near the hinged (outer) edge of the door and increases as their distance increases from their mounting edge towards the inner edge of the doors. The thickness of the doors being greatest at or near the center of the truck, where their facing sides  16   a ,  16   b  abut each other. When the doors are closed, the internal surfaces  13   a ,  13   b  of the doors face the cargo doors (if present) or the rear of the truck&#39;s cargo space if there are no cargo doors. A latch  11  is provided to lock the doors. The doors of  FIG. 1B  may be used as discussed above for the doors of  FIGS. 1 and 1A . 
         [0029]      FIGS. 7 ,  8  and  9  illustrate in greater detail the formation of a door suitable for use in the embodiment shown in  FIG. 1B .  FIGS. 7 and 8  show that the door may have a curved outer wall  5  ( 5   a ,  5   b ) instead of the straight wall shown in  FIG. 5 . The outer wall  5  extends in a curve from the outer edge  29   a  towards the outer edge (apex)  18  of the door to provide a desired aerodynamic shape for reducing drag. The upper and bottom side walls  71  and  81  shown in  FIG. 9  may be sloped as shown in  FIGS. 6 and 9 . The double doors are made to close comfortably upon each other and to operate together. It should be evident that the hinged arrangement allows the doors to be opened and closed easily and to give easy access to the contents of the cargo within the box of the truck. 
         [0030]      FIGS. 3 and 4  shows drag reducing doors A and B mounted on the rear of a truck  4 , which is a truck having vertical cargo doors which swing open to the sides of the truck. This necessitates that doors embodying the invention be mounted on the truck differently than as shown in  FIGS. 1 and 2 .  FIGS. 3 and 4  are intended to show that drag reducing doors A and B are mounted to truck  4  via hinges  22  which are connected to the drag reducer doors A and B and slideably connected to tracks  15 , the tracks  15  being secured to the sides of truck  4 . Thus, the drag reducing doors can be opened and slid towards the front of the truck  4  a sufficient distance to allow access to the truck&#39;s pre-existing cargo doors so they can be easily and fully opened. 
         [0031]    Although the drawings show the invention mounted on existing vehicles, the drag reducing doors can also be provided as replacements doors on existing vehicles or as new doors for new vehicles; thereby, eliminating the need for additional cargo doors. 
         [0032]    The interior of the drag reducing doors as shown in  FIG. 10  can be provided with shelving  21  and/or means for storage; thus, the invention in addition to reducing a vehicle&#39;s drag provides an additional benefit in that it can increase the vehicle&#39;s storage capacity. It should also be noted that the shelving within the door space provides additional stiffening support to the doors. 
         [0033]      FIGS. 11 and 12  are intended to show that a single door  510  or  512  may be used to provide the desired aerodynamic air flow for reducing drag and turbulence and also provide additional storage capacity. The single door is mounted via a hinge  91  for rotatably (as in  FIGS. 1 and 2 ) or slidably (as in  FIGS. 3 ,  4 ) opening and closing the door. The single door structure may provide an advantage where undivided storage space is desired.