Abstract:
A tonneau cover is provided that is attached at its most forward end to an adjustable tensioning rail which spans the front end of a pickup truck box. The tensioning rail is adjustably attached at its outside edges to two side rails which are attached to the inside of a pickup box. The adjustable attachment of the tensioning rail to the side rails is accomplished by the use of a tensioning screw and two attachment blocks. As the tensioning screw is moved forwards and backwards by the use of the adjustment knob, the tensioning rail is moved in a corresponding manner. This adjustment is preformed when the tonneau cover is in the open position, and thus, allows a user to obtain the desired amount if tightness when the tonneau cover is subsequently placed in the closed position.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an improvement in the manner in which a tonneau cover is attached to a pickup truck box. More specifically, a method of attachment which allows for the adjustment of the tonneau cover in order to provide the user with a means by which the tension placed upon the tonneau cover can be varied to provide a tight seal in varying conditions and as the cover ages or stretches. 
     In the past, tonneau covers have been used to cover box openings of pickup trucks to protect the contents from wind, rain and snow, or simply for cosmetic reasons. The types of tonneau covers and methods of fastening the covers have varied greatly over the years. In recent years, one type of cover that has been commonly used is a tonneau cover that attaches at one end, typically the front end nearest the cab of the vehicle, in a permanent fashion. The sides and tailgate area are fastened to box of the pickup when closed. In the open position, the cover may be rolled forward toward the cab of the pickup and the attached end of the tonneau cover. 
     The problem with this type of arrangement is that tonneau covers may stretch over time. This can be greatly affected by the weather and use or stress placed upon the tarp. As the tarp sags, it may begin to look aesthetically poor and cause problems such as puddling of water. This can be especially dangerous when the puddles freeze, resulting in chunks or sheets of ice that fly off during travel and create hazards for other drivers on the road. A second problem caused by sagging tonneau covers is wind flap. This occurs during travel of the vehicle when the tonneau cover flaps in the wind causing noise and creating undue wear and greater stretching of the cover. 
     In order to deal with this problem, tonneau cover makers have developed ways of adjusting the position of the front portion of tonneau cover. Typically, the front portion may be bolted on rail or brace system with clamps and thus, the bolts may be loosened and moved on the rail to adjust the position of the front portion of the cover, in turn affecting the tension of the cover when in the attached position. This type of system requires the use of tools and trial and error to get the correct tension of the tonneau cover. It may also be very difficult to adjust each side accurately and evenly with the other. Due to the difficulty in making these adjustments many tonneau cover owners ignore the problem of improperly adjusting the cover after installation and thus, creating undue stress and wear on the cover as well as posing a potentially dangerous condition for others on the road. 
     From this discussion it can be seen that it would be desirable to create a means of easily adjusting the tension and position of tonneau covers used on pickups today. It can also be seen that it would be advantageous to make this adjustment as easy as possible to make and to insure that users keep their covers in taught arrangement to prevent the problems listed above and to keep the tonneau cover as aesthetically pleasing as possible. 
     SUMMARY OF THE INVENTION 
     It is the primary objective of the present invention to provide a method of tightening tonneau covers that are commonly used to protect the contents of pickup truck boxes from wind, rain and snow. 
     It is an additional objective of the present invention to provide such a method that allows for the adjustment of the tightening apparatus in order to compensate for varying conditions or wear on the tonneau cover. 
     It is still a further objective of the present invention to provide a such a method that can be employed in an inexpensive and effective manner. 
     These objectives are accomplished by the use of a tonneau cover that is attached at its most forward end to an adjustable tensioning rail which spans the front end of a pickup truck box. The attachment of the tonneau cover is accomplished by the use of small diameter rope, rod or the like, that is sewn into a loop along the entire forward edge of the cover. The rope and tonneau cover loop are then slid into a receptor channel located along the front lower edge of the tensioning rail which securely holds the leading edge of the tonneau cover in place. This design allows the amount of tension placed on the tonneau cover to be varied by adjusting the location of the tensioning rail, thereby, allowing the user to obtain the desired degree of tension on the installed tonneau cover, when latched. 
     The tensioning rail is adjustably attached at its outside edges to two side rails which are attached to the inside of a pickup box by the use of a plurality of C-type clamps bolts or the like. The adjustable attachment of the tensioning rail to the side rails is accomplished by the use a tensioning screw and two attachment blocks. The side rails have fixedly mounted blocks through which one end of the tensioning screws pass. The portion of the block through which the screw passes is interrupted at its center by an open space which houses the screw adjustment knob which is in turn threaded over the tensioning screw. Therefore, as the adjustment knob is rotated, the tensioning screw will travel either forwards or backwards within the attachment block because the lateral travel of the adjustment knob is limited by the two sides of the attachment block. 
     The attachment of the tensioning rail to the tensioning screw is accomplished by using another fixedly mounted block that extends downward from the lower surface of the tensioning rail, just inside of where the tensioning rail sits on the side rail. The tensioning screw again passes through this block but is fixedly mounted to the block by a stop nut that is threaded down the length of the screw until it contacts the block, where it is tightened to hold the screw in place. Therefore, as the tensioning screw is moved forward and backward, with the cover in the open position by the use of the adjustment knob, the tensioning rail is moved in a corresponding manner which serves to adjust the tension placed upon the tonneau cover when subsequently placed in the closed and latched position. 
    
    
     
       For a better understanding of the present invention reference should be made to the drawings and the description in which there are illustrated and described preferred embodiments of the present invention. 
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the present invention showing the orientation of the invention when it is fitted to the box of a typical pickup box. 
         FIG. 2  is a top elevation view cut-away of the present invention showing the orientation of the tonneau cover and the location and method of construction of the tensioning rail apparatus. 
         FIG. 3  is a side elevation cut away view of the present invention showing the manner in which the tensioning screw is attached to and controls the positioning of the tensioning rail and the tonneau cover. 
         FIG. 4  is a bottom elevation cut-away view of the present invention again showing the manner in which the tensioning screw is attached to and controls the positioning of the tensioning rail and the tonneau cover. 
         FIG. 5  is a front elevation cut-away view of the present invention detailing the manner in which the side rails are attached to the pickup box and the orientation of its major components in relation to the side rails. 
         FIG. 6  is a side elevation cut-away view of the present invention showing the tensioning screw when the tonneau cover is in an unlocked state with no tension. 
         FIG. 7  is a side elevation cut-away view of the present invention showing the tensioning screw fully engaged, or with tension on the tonneau cover. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, and more specifically to  FIGS. 1 and 2 , the tonneau cover tension adjuster apparatus  10  is made up of a tonneau cover  12  which fits over and covers the opening of a pickup truck box  66  of a typical pickup truck  64 . The tonneau cover  12  extends from just behind the pickup cab  70  back to the tail gate  68  located at the most rearward portion of the truck box  66 . This is accomplished by the use of a pair of apparatus side rails  14  which are attached to and run down the entire length of the upper outside edges of the truck box  66 . The side rails  14  form the outside frame of the tonneau cover  12  and are the base upon which the cover tensioning rail  16  is attached. The side rails  14  also contain at their forward ends, a pair of graduated measuring scales  15  which give the user a point of reference to ensure that each side of the tensioning rail  16  places the same degree of tension on the tonneau cover  12 . 
     The tensioning rail  16  provides the forward attachment point for the front edge of the tonneau cover  12  and is mounted to the side rails  14  in a manner that allows it to slide forward and rearward to provide the tonneau cover  12  with the motion necessary to either be stretched tightly over the truck box  66  or to be loosened. The attachment and sliding motion of the tensioning rail  16  are both provided by the tensioning screw  18  and the adjustment block  22  located on the most forward underneath end of the side rails  14 . Thus, a user can vary the lateral tension placed on the tonneau cover  12  to ensure that it provides a tight seal in all conditions between the interior of the pickup box  66  and the outside elements even in high wind conditions, such as highway driving. 
     The construction of the mounting and adjustment portion of the tensioning rail  16  of the present invention are detailed in  FIGS. 3 and 4 . The tensioning rail  16  is perpendicularly mounted between the two side rails  14  at their most forward ends by the use of the adjustment block  22 , the tensioning screw  20  and the tensioning rail attachment block  30 . The adjustment block  22  is attached to the lower surface of the side rail component mount surface  44  which is the flat laterally extending portion of the side rails  14 . This attachment is accomplished by passing the adjustment block attachment bolt  24  downward through both the component mount surface  44  and the adjustment block  22  where it is secured by the attachment nut  26  located on the underneath surface of the adjustment block  22 . 
     The most outward portion of the adjustment block  22  forms two, side by side cylindrical members through the center of which the tensioning screw  18  is passed. In between these two members lies the screw adjustment knob  20 . The screw adjustment knob  20  is threaded onto the tensioning screw  18 . Its lateral travel is limited by the cylindrical members of the adjustment block  22 . Therefore, when the screw adjustment knob  20  is rotated, the tensioning screw  18  moves either forward or rearward, depending upon the direction of rotation of the tensioning screw  18 , which controls the orientation of the tensioning rail  16  in relation to the side rails  14 . 
     From the adjustment block  22 , the tensioning screw  18  extends forward to where it passes through the tensioning rail attachment block  30 . At its most forward end, the tensioning screw&#39;s  18  lateral travel is limited by the screw head, which rests against the outside forward edge of the rail block  30 . The most forward portion of the tensioning screw  18  is then held in a locked position within the tensioning rail attachment block  30  by the use of the tensioning screw stop nut  28 . The tensioning screw lock nut  28  is threaded down the length of the tensioning screw  18  until it comes in contact with the rearward surface of the rail block  30 . At this point, it is tightened into place so as to hold the tensioning screw  18  securely within the rail block  30 . In another embodiment (not shown) the tensioning screw stop nut  28  may be eliminated by molding the tensioning screw  18  and screw head directly into the rail back  30 . Thus, the tensioning screw  18  and the rail block  30  would be one piece. In both embodiments, when the tensioning screw  18  is moved forward or rearwardly by the use of the screw adjustment knob  20 , the rail block  30  is moved accordingly. 
     The tensioning rail attachment block  30  is held in place on the lower surface of the tensioning rail  16  by extending the rail block attachment bolt  32  upwards through the rail block  30 . The attachment bolt  32  extends beyond the upper surface of the rail block  30  to where it passes when the rail block  30  is placed against the lower surface of the tensioning rail  16 , into the tensioning rail attachment chamber  36 . The rail attachment chamber is an opening within the tensioning rail  16  which has a narrow downward facing opening through which the attachment bolt  32  passes. The interior of the attachment chamber  36  is therefore larger than the opening for the attachment bolt  32  which creates a flat surface on either side of the passage upon which the rail block attachment nut  34  rests. Thus, when the attachment nut  34  is placed within the attachment chamber  36 , the attachment bolt  32  is threaded and tightened into the attachment nut  34  which serves to hold the tensioning rail block  30  against the bottom surface of the tensioning rail  16 . This construction method serves both to secure the tensioning rail  16  to the side rails  14 , and to provide a means by which the tensioning rail  16  can be adjusted to vary the tension placed on the tonneau cover  12 , when latched. 
     The tonneau cover  12  is attached to the tensioning rail  16  by use of the tonneau cover attaching rope  40 . The attaching rope  40  is a length of small diameter rope that is sewn into a loop at the most forward edge of the tonneau cover  12 . The attaching rope  40  and the loop are inserted into the attaching rope channel  42  located on the lower most forward surface of the tensioning rail  16 . The tonneau cover  12  extends rearward from this point over the upper tensioning rail surface  38  and continues back to cover the pickup truck box  66  where it is anchored at a location above the tailgate  68 . This connection allows the adjustable tensioning rail  16  to vary the position of tonneau cover  12  in order to provide a tight seal over the truck box  66 . 
     The construction of the side rails  14  is illustrated in FIG.  5 . The side rails  14  are generally L-shaped components having the short portion of the “L” forming a vertical surface extending downward from the most outside edge of the side rail  14 . This vertical portion is the side rail to truck clamp surface  46  and has on its inner surface a series of ridges called clamp cleats  48 . The truck clamp surface  46  provides the point of attachment for securing the side rails  14 , and the present invention, to the upper and inner surface of the truck box  66 . This attachment is accomplished by the use of a plurality of attachment clamps  50 , which are generally C-shaped clamping devices, with one portion of the opened end of the “C” engaging the inner surface of the truck box  66  and the other engaging the clamp cleats  48  on the truck clamp surface  46  of the side rails  14 . The clamp cleats  48  provide a roughened surface for the attachment clamp  50  to engage ensuring a secure attachment of the present invention and the tonneau cover  12  to the pickup truck box  66 . 
     The longer portion of the L-shape of the side rails  14  forms the side rail component mount surfaces  44  to which the mounting apparatus for the tensioning rail  16  and the tensioning screw  18  are attached. Additionally, each of the side rails  14  also have an upwardly oriented diagonal surface  52  which serves as both the outward cosmetic edge of the side rails  14  and as guides or frames within which the tonneau cover  12  is stretched. Additionally, the tensioning rail  16  is also equipped with two tensioning rail end caps  54  which fit over each end of the tensioning rail  16  just inside of the side rail diagonal surface. 
     The method of operation of the tonneau cover tension adjuster apparatus  10  is further illustrated in  FIGS. 6 and 7 . To reduce the tension or loosen the tonneau cover  56  for either its removal or installation, the user rotates the screw adjustment knob  20  in a clockwise manner which serves to pull the tensioning rail  16  back through the tensioning screw  18  and the tensioning rail attachment block  30  (the loosening movement accomplished by this operation is illustrated by the directional arrows labeled as  60 ). Conversely, to obtain a tensioned or taught tonneau cover  58 , when latched one simply reverses this process by rotating the screw adjustment knob  20  in a counter-clockwise manner which serves to force the tensioning rail  16  forward through the tensioning screw  18  and tensioning rail attachment block  30  (the tensioning movement accomplished by this operation is illustrated by the directional arrows labeled as  62 ). 
     Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.