Abstract:
The cargo carrier is a monocoque hollow shell enclosure designed to carry cargo without substantially adding aerodynamic drag to an automobile. The carrier is installed on top of an appropriate motor vehicle and has a smooth outer surface and is in the shape of an airfoil, preferably a symmetrical airfoil, which minimizes aerodynamic drag. The top of the cargo carrier includes an access door attached by a hinge to the cargo carrier. The cargo carrier has two mounting members on either side, which sit in a support frame attached to factory installed roof rack rails, thus supporting the cargo carrier above the vehicle.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a cargo carrier that can be mounted on the top of an automobile and that is shaped to minimize aerodynamic drag. The cargo carrier is supported above the roof of an automobile and has a profile shape defining a nearly symmetrical airfoil.  
         [0003]     2. Description of the Related Art  
         [0004]     Drivers often need to transport luggage, sports equipment, and/or camping gear or the like, which cannot be stored in the interior or in the trunk of a vehicle. Rooftop cargo containers and rack systems have been used to transport these bulky items for drivers, but these bulky cargo carriers increase the air drag on the vehicle, thus reducing fuel efficiency.  
         [0005]     German Patent No. 1,939,154, published Feb. 11, 1972, discloses a bulky luggage box supported above an automobile. The luggage box has a non-airfoil shape with blunt front and rear ends, a flat bottom side, and a nearly flat upper side.  
         [0006]     The majority of luggage boxes for motor vehicles are adapted to sit directly against, or in close proximity to, the roof of an automobile. These bulky luggage boxes result in considerable aerodynamic drag and thus significantly reduce the fuel efficiency of the automobile. Patents disclosing such luggage boxes include U.S. Pat. No. 6,234,371, issued May 22, 2001 to J. Sinn; U.S. Pat. No. 5,713,498, issued Feb. 3, 1998 to C. Cucci; U.S. Pat. No. 4,974,766, issued Dec. 4, 1990 to DiPalma et al.; U.S. Pat. No. 3,095,129, issued Jun. 25, 1963 to R. W. Kerr; U.S. Design Pat. No. 326,634, issued Jun. 2, 1992 to J. Seaver; German Patent No. 2,048,462, published Apr. 6, 1972; and French Patent No. 2,695,890, published Mar. 25, 1994.  
         [0007]     Various roof rack systems have been used to help drivers store and transport items that will not fit within the interior or the truck of a vehicle. Patents disclosing such roof rack systems include U.S. Pat. No. 6,561,397, issued May 13, 2003 to Bauer et al.; U.S. Pat. No. 5,282,560, issued Feb. 1, 1994 to R. Ozog; U.S. Pat. No. 5,174,484, issued Dec. 29, 1992 to J. Bott; and U.S. Design Pat. No. 406,557, issued Mar. 9, 1999 to G. Bentley.  
         [0008]     None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus, a cargo carrier solving the aforementioned problems is desired.  
       SUMMARY OF THE INVENTION  
       [0009]     The cargo carrier is a monocoque hollow shell enclosure designed to carry cargo without substantially adding aerodynamic drag to an automobile. It is installed on top of an appropriate motor vehicle. The cargo carrier has a smooth outer surface and is in the shape of an airfoil, preferably a symmetric airfoil, which minimizes aerodynamic drag. The top of the cargo carrier includes an access door attached by a hinge to the cargo carrier. The cargo carrier has two mounting members extending to each side, which sit in a support frame attached to factory installed roof rack rails, thus supporting the cargo carrier above the vehicle.  
         [0010]     The support frame has four uprights having clamps at their base for attachment to the roof-mounted rack rails, and bearing members attached to the top of each upright journalled to receive the mounting members extending from the cargo carrier. When installed onto an automobile, the base of each upright is clamped onto the automobile&#39;s roof rack rails and carrier&#39;s support members are inserted through the bearing members. A crossbar connects a pair of uprights on each side of the vehicle, giving stability to the support frame.  
         [0011]     These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is an environmental, perspective view of a cargo carrier according to the present invention.  
         [0013]      FIG. 2  is an environmental side view of the cargo carrier of the present invention.  
         [0014]      FIG. 3  is an environmental rear view of the cargo carrier of the present invention.  
         [0015]      FIG. 4  is a top view of the cargo carrier of the present invention.  
         [0016]      FIG. 5  is a perspective view of a support structure for the cargo carrier of the present invention.  
         [0017]      FIG. 6  is a side view of the support structure of  FIG. 5 .  
         [0018]      FIG. 7  is an end view of the support structure of  FIG. 5 .  
     
    
       [0019]     Similar reference characters denote corresponding features consistently throughout the attached drawings.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     As depicted in  FIG. 1 , the present invention is a cargo carrier, generally indicated as  10 , adapted to be supported above the roof of an automobile A to carry luggage, sports equipment and/or camping gear while providing minimal aerodynamic drag to the automobile A. The cargo carrier  10  has a main body  12  having an airfoil cross-sectional shape. An airfoil shape is a shape designed to control stability, direction, lift, thrust, or propulsion. An airfoil generally has a blunt leading edge, smooth top and bottom surfaces, and a relatively sharp trailing edge. It is desired in the present invention to provide a cargo carrier  10  with an airfoil shaped and oriented to minimize the disruption of air flowing around the cargo carrier  10 , thus minimizing aerodynamic drag. The front end  14  (the leading edge) of the main body  12  has a larger radius of curvature than the rear end  16  (the trailing edge) of the main body  12 , or the rear end  16  may come to a point as viewed from the side. The front end  14  is oriented towards the front end of the automobile.  
         [0021]     A door  18  is attached to the main body  12  by a hinge  20 , permitting a user to access the hollow chamber defined within the main body  12  to insert or remove objects to be stored and transported within the cargo carrier  10 . The hinge  20  is preferably positioned at the portion of the door  18  that is nearest to the front end  14  of the main body  12 . The hinge  20  is positioned in or behind a plane (indicated by dashed line  26  in  FIG. 2 ) normal to the chord of the main body  12  that extends through the maximum height of the main body  12 .  
         [0022]     Each side of the cargo carrier  10  includes two mounting members  22  extending laterally from the main body  12 . The mounting members  22  fit into apertures journalled in the two side support assemblies  30 , which are each attached to the standard roof rails B of the automobile A. The mounting members  22  are depicted as cylindrical, but may be provided with a more aerodynamic shape. The apertures defined in the support assemblies  30  generally conform to the cross sectional shape of the mounting members  22 . The mounting members  22  are sufficiently long to allow the cargo carrier  10  to be placed on a variety of automobiles A with vertical roof rails B spaced at different standard intervals. It is also possible to adapt the side support assemblies  30  to support the cargo carrier  10  above an automobile A having different roof rail arrangements, including horizontal roof rails.  
         [0023]     As depicted in  FIG. 2 , the cargo carrier  10  preferably has a substantially symmetrical airfoil shape. An airfoil shape is based upon aircraft airfoil data, which define airfoil cross-sectional shapes. Airfoils may be designed and oriented to create lift or a downward force, but such up or down forces also create aerodynamic drag. It is thus the goal of this invention to provide a cargo carrier that provides negligible upward or downward force so that the aerodynamic drag is minimized. A symmetrical airfoil shape is one in which the bottom portion of the airfoil is the mirror image of the top portion of the airfoil. A symmetrical airfoil shape oriented at a zero degree angle of attack is the optimal shape and orientation for minimizing aerodynamic drag.  
         [0024]     Viewed from the side, an airfoil has a curved leading edge and pointed trailing edge. Airfoils are described by their chord, mean camber, thickness, and thickness distribution. The chord line is a straight line joining the leading edge to the trailing edge, designated as line  28  for the airfoil shape depicted in  FIG. 2 . In a symmetrical airfoil, the distance from the chord line  28  to the upper surface is the same as the distance from the chord to the lower surface at every point along the chord. The mean camber line is the curvature of the median line of the profile of the airfoil.  
         [0025]     An airfoil also has a stagnation point, which is the point on the airfoil body where an airstream directed at the leading edge of the wing has a velocity equal to zero, usually where the air stream divides to travel above and below the airfoil. The stagnation point is not fixed, but changes with the angle of attack, i.e., the angle between the chord and the velocity of the air stream. The shape of the airfoil and its orientation relative to airflow will determine the degree of lift or down force, which both create aerodynamic drag. The cargo carrier  10  has an airfoil shape designed to minimize aerodynamic drag and thus creates minimal lift or down force. Thus, the cargo carrier  10  is preferably designed to be oriented with a zero degree angle of attack, and therefore the chord  28  is oriented substantially parallel to the relative ground line.  
         [0026]     As depicted in  FIGS. 1-4 , the main body  12  may have a NACA0017 symmetrical airfoil shape, which has a maximum thickness that is seventeen percent of the chord length. (In the National Advisory Committee for Aeronautics (NACA) system of designation, the first digit is the maximum camber in percent of chord, the second digit is the location of the position of maximum camber in tenths of chord measured from the leading edge, and the last two figures represent the maximum thickness in percent of chord.) Alternatively, the main body  12  may have other symmetrical or near symmetrical airfoil shapes, such as the airfoil defined by the NACA 0018 airfoil or a symmetrical laminar airfoil shape, which has the point of maximum thickness (depicted by line  26  in  FIG. 3 ) closer to the rear end  16  of the airfoil.  
         [0027]      FIG. 3  shows a rear view of the cargo carrier  10  supported above an automobile A. The main body  12  is shown having a constant cross-sectional symmetrical airfoil shape with flat sides, but the main body  12  may vary in cross-sectional size, as long as every vertical cross section of the main body  12  has an airfoil shape, preferably a symmetric airfoil shape. For example, the main body  12  could have a larger cross-sectional symmetric airfoil shape in the middle and gradually decrease in size towards the sides.  
         [0028]      FIG. 4  shows a top view of the cargo carrier  10 . The hinge  20  of the door  18  is attached within the hollow cavity of the main body  12  towards the front end  14  of the main body  12 . The main body  12  defines an opening corresponding to the shape of the door  18  so that when the door  18  is in a closed position, the hollow cavity is completely encased. A shelf  24  is provided along the inside periphery of the aperture. The periphery of the door  18  rests on the shelf  24  such that the door  18  is flush with the upper surface of the main body  12 . The shelf  24  is preferably integral with the main body  12  of the cargo carrier  10 , and may have a seal attached thereto for watertight integrity.  
         [0029]     The cargo carrier  10  could be made in a variety of sizes, but one optimal design has a length of 84.34 inches, a main body  12  width of 28.12 inches, a maximum thickness of 14.72 inches, and mounting members  22  that each extend from the sides of the main body  12  by 7.94 inches. The distance between each mounting member  22  on each side is preferably about 30.1 inches. It has been found that this size cargo carrier  10  would fit on most automobiles and would accommodate a variety of luggage sizes and sports equipment, but smaller and larger sizes are also anticipated.  
         [0030]     The cargo carrier  10  is preferably made out of fiberglass, but may also be made of any sufficiently rigid material including aluminum, other metals, and various plastics.  
         [0031]      FIGS. 5-7  depict a side support assembly  30  in detail.  FIG. 5  is a perspective view,  FIG. 6  is a side view, and  FIG. 7  is an end view of the side support assembly  30 . The side support assembly  30  preferably includes two spaced uprights  32  each having a top end and a bottom end. The uprights  32  are preferably fixed in the desired spaced relationship by a crossbar  52 . The crossbar  52  adds stability to the support frame  30  and fixes the two uprights  32  in the exact spacing of the two carrier protrusions  22  on each side of the cargo carrier  10 . The crossbar  52  is attached to the uprights  32  at each end by two bolts  54 .  
         [0032]     Each upright  32  has a two-piece bearing block  34  attached to its upper end. The bearing blocks  34  are journalled to the cross-sectional shape of the mounting members  22 , defining circular apertures. Bolts  38  are used to secure the bearing blocks  34  to the upper end of each upright  32 . The bearing blocks  34  optionally include a front plate  36 . The bearing blocks  34  are sufficiently thick to properly support the cargo carrier  10  above the automobile. The bearing blocks  34  and front place  36  of the present invention are sold by ZSi Corporation under the trade name BETA CLAMP.  
         [0033]     An L-shaped bracket  40  is attached to the bottom end of each upright  32  by bolts  50 . The second leg of the L-shaped bracket  40  extends normal to the upright  32  and is approximately flush with the bottom end of the upright  32 . A lower clamping face  46  is attached below the second leg of the L-shaped bracket  40  by two clamping bolts  48 . The upper side of the lower clamping face  46  is provided with a bottom compression layer  42  and the lower side of the second leg of the L-shaped bracket  40  is provided with a top compression layer  44 . The compression layers  42  and  44 , or gaskets, are of a compressible semi-soft rubber or other suitable easily compressible layer of material that will securely grip the roof rail B, thereby clamping the support assembly  30  to the roof rail B. The top compression layer  44  is preferably thicker than the bottom compression layer  42  because roof rails B usually have substantially flat bottom surfaces and varying top surfaces. The top compression layer  44  is preferably two to four times thicker than the bottom compression layer  42 .  
         [0034]     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.