Abstract:
A drag reduction device secured to each of the top rails of a wheeled cargo van body or container which covers the recess formed in the outer side of the top rail.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a drag reduction apparatus for a trailer and more particularly to a drag reduction apparatus which is secured to each of the upper side rails of the body of the trailer. Even more particularly this invention relates to a cover member which is secured to each of the upper side rails so as to extend over the recesses in the upper side rails to prevent air flow from entering the recesses. 
     2. Description of the Related Art 
     Semi-trailer bodies have a floor with a forward end, a rearward end, a left side and a right side. A front wall extends upwardly from the forward end of the floor, a left wall extends upwardly from the left side of the floor, and a right wall extends upwardly from the right side of the floor. A rear wall including door supporting structure is provided at the rearward end of the floor for supporting one or more doors therein. An elongated left upper side rail is secured to the upper end of the left wall and an elongated right upper side rail is secured to the upper end of the right wall. A forward upper rail is secured to the upper end of the front wall. In some semi-trailer bodies, a rearward upper rail is secured to the upper end of the rear wall. In some cases, curved rail portions join the front ends of the upper side rails to the outer ends of the front upper rail. In some cases, curved rail portions join the rear ends of the upper side rails to the outer ends of the rear upper rail. A roof is secured to the upper rails and extends therebetween. 
     In many trailers, the upper side rails have a recess portion formed therein at the outer side thereof. Air flow impinging in the recessed portions of the upper rails will create an aerodynamic drag which will have an impact on the fuel consumption of the truck pulling the trailer. The recessed portion in the front upper rail does not pose any appreciable aerodynamic drag since drag reduction devices are commonly mounted on the roof of the truck to cause the airflow to pass upwardly over the front upper rail. However, in some cases, the drag reduction devices on the cab roof do not prevent air flow from impinging into the recessed portion of the front upper rail. Further, since most trucks and trailers are subjected to cross winds, air flow will be impinged into the side upper rails into the recessed areas thereby creating an aerodynamic drag having an impact on the fuel consumption of the truck. 
     SUMMARY OF THE INVENTION 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key aspects or essential aspects of the claimed subject matter. Moreover, this Summary is not intended for use as an aid in determining the scope of the claimed subject matter. 
     A drag reduction apparatus is disclosed for a trailer having an elongated, horizontally extending upper side rail at the upper end of each of the side walls of the trailer with the upper rail having an elongated, horizontally extending recess formed therein which receives a side edge of a roof member having upper and lower sides. In some trailer bodies, the edges of the roof do not extend into the recessed portions of the top rails. Those designs also suffer from the same drag problems as the upper rails wherein the roof edges extend into the recessed portions of the top rails. The drag reduction apparatus of this invention comprises an elongated, horizontally extending cover member having an upper inner end and a lower outer end. The upper inner end of the cover member is secured to the upper side of the roof member. The lower outer end of the cover member is secured to the upper rails so that the cover member extends over the recess in the upper rails to prevent air flow from entering the recesses thereof. 
     The cover member is preferably comprised of plastic, aluminum, fiberglass or other suitable material and preferably comes in 12-foot sections. The drag reduction apparatus may be factory installed or retrofitted onto existing trailers. 
     Therefore, it is a principal object of the invention to provide a drag reduction device for a trailer. 
     A further object of the invention is to provide a drag reduction device which covers the elongated horizontally extending recess in the upper rails of the trailer. 
     A further object of the invention is to provide a device of the type described which may be factory installed or which may be retrofitted onto an existing trailer. 
     A further object of the invention is to provide a device of the type described which is easily affixed to the trailer. 
     These and other objects will be apparent to those skilled in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. 
         FIG. 1  is a partial perspective view of a conventional semi-trailer having the top side rails covered with the drag reduction apparatus of this invention; 
         FIG. 2  is a partial perspective view of the drag reduction apparatus of this invention which illustrates two of the sections thereof and the manner in which they are connected together; 
         FIG. 3  is a sectional view of one form of the top upper rail commonly used on trailers; 
         FIG. 4  is a sectional view illustrating the drag reduction apparatus of this invention extending over the top side rail of  FIG. 3 ; 
         FIG. 5  is a partial perspective view illustrating the drag reduction apparatus of this invention extending over top side rail of  FIG. 3 ; 
         FIG. 6  is a sectional view similar to  FIG. 3  except that it shows a different form of a top side rail of a trailer; 
         FIG. 7  is a view similar to  FIG. 4  except that the drag reduction apparatus of this invention is attached to the top side rail in the configuration of  FIG. 6 ; and 
         FIG. 8  is a partial perspective view similar to  FIG. 5  except that the drag reduction apparatus of this invention is shown to be extending over the top side rail in the configuration of  FIG. 6 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Embodiments are described more fully below with reference to the accompanying figures, which form a part hereof and show, by way of illustration, specific exemplary embodiments. These embodiments are disclosed in sufficient detail to enable those skilled in the art to practice the invention. However, embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. The following detailed description is, therefore, not to be taken in a limiting sense in that the scope of the present invention is defined only by the appended claims. 
     In  FIG. 1 , the numeral  10  refers to a conventional semi-trailer having a forward end  12 , a rearward end  14 , a right side wall  16 , a left side wall  18 , a rear wall  20  having doors  22  and  24  mounted therein, a roof  26 , and a wheel assembly  28  which may be of the single axle style or the tandem axle style shown in  FIG. 1 . 
     Each of the side walls  16  and  18  have a top or upper rail secured thereto which connects the side wall to the roof.  FIGS. 3-5  illustrate one form of the top side rails such as found on trailers manufactured by Great Dane Limited Partnership with the top side rail being designated by the reference numeral  30 .  FIGS. 6-8  illustrate another style of the top side rail which is designated by the reference numeral  32 . 
     Top side rail  30  extends along the upper end of side wall  16  for the length thereof. Top side rail  30  includes an upper horizontally disposed member  34 , a vertically disposed member, a horizontally extended member  38 , which extends inwardly from the lower end of member  36 , a horizontally extending member  40  which extends outwardly from the lower end of member  36 , and a vertically extending member  42  which extends downwardly from the outer end of member  40 . As seen in  FIG. 3 , the side edge of roof  26  extends around the outer end of member  34 . A longitudinally extending row of rivets  44  extend through roof  26  and member  34  to connect the roof  26  to the top side rail  30 . A longitudinally extending row of rivets  46  extend through side wall  16  and member  42  to connect the side wall  16  to top side rail  30 . The ends of cross members  48  are supported upon the member  38  as seen in  FIG. 3 . The configuration of top side rail  30  creates a recess  50  which extends the length of the top rail  30 . As the trailer is pulled by a truck, cross winds create an air flow into the recess  50  thereby creating an aerodynamic drag which impacts the full consumption of the truck. If the truck is driving into a head wind, the air flow will enter the recess in the top front rail. 
     Top rail  32  is similar to top rail  34  except for the fact that the side wall  16 ′ is a double skin side wall. The rail  32  has a recess  52  at its outer side which presents the same drag as recess  50  in the top rail  30 . 
     A top side rail identical to top side rail  32  (not shown) is secured to the upper end of left side wall  18 . further, in most trailer designs, a front top rail is secured to the upper end of the front wall of the trailer. Also, in some cases, a top rear rail is secured to the upper end of the rear wall  20 . Additionally, the forward ends of the top side rails are joined to the outer ends of the front top rail by curved rail sections. The same is also true for the juncture of the outer ends of the rear top rail and the rear ends of the top side rails. 
     Applicant has designed a drag reduction apparatus or device  54  to prevent air flow from cross winds from impinging into the recess  50  of top rail  30  and from impinging into the recess  52  of top rail  32 . The device  54  will also be secured to the outer top rails as well as the curved corners thereof. Device  54  is elongated and arcuate or curved as seen in the drawings and is preferably constructed of plastic, aluminum, fiberglass or other suitable material. Preferably, device  54  is fabricated in 12-foot lengths so that four of the segments may be joined together for a 48-foot top rail. If the trailer is 53 feet long, four 12-foot lengths will be joined together with a 5-foot segment being cut from a 12-foot segment to create a length of 53 feet. 
     For purposes of description, device  54  will be described as having an upper inner edge  56  and a lower outer edge. If the device  54  is being used to cover the recess  50  of top rail  30 , the upper inner edge  56  is secured to the upper surface of roof  26  by a suitable adhesive  60  or the like. The lower outer edge  58  is secured to the outer surface of member  42  of top rail  30  by a suitable adhesive  62  or the like. When the device  54  is positioned as shown and described, the device  54  prevents cross-wind air flow into recess  50  thereby reducing the drag resistance of the top rail  30 . If desired, the lower outer edge  58  of device  54  could be secured to the outer surface of wall  16  below the lower end of top rail  30 . 
     When the device  54  is being used with a top side rail  32 , the lower outer edge  58  is secured to the top rail  32  as seen in  FIGS. 7 and 8  to cover the recess  52  to reduce the aerodynamic drag of the top rail  32 . If desired, the lower outer edge  58  of device  54  could be secured to the outer surface of wall  16  at the upper end thereof. The ends of the device  54  should be closed with caps  64 , as seen in  FIG. 2 , or with curved cover sections. 
     The device  54  of this invention may be factory installed or installed on existing trailers. The device  54  will work equally well with the upper side rails of a van or cargo body of a straight truck. Thus, it can be seen that the drag reduction device of this invention accomplishes at least all of its stated objectives. 
     Although the invention has been described in language that is specific to certain structures and methodological steps, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific structures and/or steps described. Rather, the specific aspects and steps are described as forms of implementing the claimed invention. Since many embodiments of the invention can be practiced without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.