Patent Abstract:
A streamlined truck cab fairing (15) for use with a pickup truck which may be mounted on the truck cab (1) without interfering with the operation of a truck bed cover. The fairing (15) includes a left panel (17) a central member (16) and a right panel (18), the lower edges (20,22) of the fairing (15) being remotely spaced from the sidewalls (14) of the truck bed, thereby forming a gap (59) through which a sheetlike cover may pass to completely seal off the truck bed region. A plurality of air inlets (29,30,31) cost the relative wind to create a reaction force pressing the fairing (15) towards the truck. A side panel reinforcing member (48) is used to reduced vibration of the fairing side panels (17,18).

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to motor vehicle accessories and more particularly to an improved apparatus and method of providing an air spoiler or cab fairing which may be mounted over the cab, or passenger compartment, of a pickup truck. 
     2. Description of the Related Technology 
     The cab portion of a conventional pickup truck typically has a rectangular appearance and a depth sufficient only to accommodate the comfortable seating of passengers. In order to maximize the cargo capacity in the pickup truck bed or &#34;box&#34;, the cab typically terminates in a near vertical wall immediately behind the passenger seats. Although this arrangement tends to maximize the available cargo carrying space within the bed of the pickup truck, the rectangular cab structure projecting abruptly into the air stream tends to create a high drag force as the vehicle travels along the road. 
     In an effort to more smoothly direct the flow of air over the cab of the pickup truck, numerous streamlined fairing shapes have been proposed to reduce drag and improve vehicle mileage. These devices can also be decorative. Additional advantages include the reduction of air turbulence within the truck box, protection of the cargo carried within the box, and increased surface area of the vehicle roof so as to permit the mounting of lights, antennas or horns. Such fairings can also partially block the sun in order to keep the cab interior cooler and reduce glare. Unfortunately, such fairings or spoilers are seldom included in pickup trucks as they leave the factory, and so the device must be retrofitted to existing vehicles. 
     In the past, spoilers and fairings have typically been mounted by connecting the spoiler to both the cab and the truck box. This mounting arrangement presents several problems. First, mounting of the device is complicated since alignment between the mounting structures on the cab and on the truck box must be perfectly matched in order to fit properly with the fairing structure. Second, the cab and the box often behave as two discrete structures. Any differential movement between these two structures can result in cracking or warping of the fairing if the fairing is rigidly attached to both regions of the truck. Finally, the traditional mounting arrangement prevents the use of a conventional truck box cover since the cover is typically attached to the truck box in the same region in which the fairing is mounted. This creates the necessity of constructing a custom truck box cover, or more frequently, utilizing an existing truck box cover but failing to fasten it completely in the area behind the cab. This defeats the purpose of the box cover insofar as it permits moisture, sunlight and dust to enter the otherwise protected cargo area. 
     Examples of conventional pickup truck fairings and covers are shown, for example, in U.S. Design Pat. No. 281,487, issued to Chapman, in which the faired rear portion of the cab abuts the box cover. The fairing shown in the &#39;487 patent could not be easily retrofitted to an existing vehicle, since it would require substantial modification of the body of the cab. U.S. Design Pat. No. 286,143, issued to Lund discloses an air spoiler for pickup trucks which may be easily retrofitted to an existing cab. However, the &#39;143 design interferes with the perimeter of the existing truck box and would, therefore, make the use of an existing box cover impossible. 
     U.S. Design Pat. No. 294,242, issued to O&#39;Neill shows a truck cover incorporating fairing arrangement, in which the fairing and the cover must be custom designed to fit together. Note that the truck cover abuts the fairing, with the fairing also serving as a portion of the cover itself. 
     U.S. Design Pat. No. 295,084, issued to Weber, depicts a retrofittable spoiler which supports a light bar. The mounting arrangement involves fastening a light bar directly to the sidewalls of the truck box, thereby requiring the use of a custom made cover for the box. 
     SUMMARY OF THE INVENTION 
     The present invention addresses some of the shortcomings of previous cab fairings by providing a novel structure which mounts only to the pickup truck cab. Any number of convenient mounting methods maybe used to rigidly attach the fairing to the cab, such as drilling a plurality of holes within the cab and attaching the fairing structure by means of traditional nuts and bolts. The use of rivets, welds, adhesives, magnets, or flexible mounts could also be adapted to secure the present invention to a truck cab. The fairings include two substantially vertical side portions which extend rearwardly of the cab and which approach the sides of the truck box. Unlike previous devices, however, the fairing does not join the sides of the truck box, but rather a small space or gap is preserved in order that a conventional box cover may be attached along the entire perimeter of the truck bed without interference from the fairing structure. Additionally, in order to prevent vibration or unwanted deformations of the fairing, structural members are employed which stiffen and stabilize the fairing. These structural members are attached directly to the cab rather than to the truck bed or any portion of the cargo holding area. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a fairing constructed according to the principles of the present invention, with the truck upon which the fairing is mounted shown in phantom; 
     FIG. 2 is a front elevation of a fairing as shown in FIG. 1; 
     FIG. 3 is a rear elevation of a fairing as depicted in FIG. 1, showing one form of mounting and stiffening; 
     FIG. 4 is a side elevation of a fairing as shown in FIG. 1; 
     FIG. 5 is a top plan view of a fairing as shown in FIG. 1; 
     FIG. 6 is a bottom plan view of a fairing as shown in FIG. 1; 
     FIG. 7 is a perspective view showing details of the stiffening arrangement as utilized in a preferred embodiment of the fairing shown in FIG. 1; and 
     FIG. 8 is a partial rear elevation of a fairing as shown in FIG. 1, showing the relationship of a portion of the fairing with the truck box. 
     FIG. 9 is a partial perspective view of the fairing as depicted in FIG. 1, showing certain details of the installation process. 
     FIG. 10 is a partial right side elevation of the fairing as depicted in FIG. 1, showing a preferred method of supporting the central bar portion of the fairing. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring particularly to FIG. 1, a partial view of a truck cab 1 is showed in phantom. The portion visible in the figure would typically be the driver&#39;s side, with lock 2 being adjacent to door handle 3, both of which are somewhat below window 4. The door 5 is typically mounted on hinges (not shown) which connects the forward perimeter 6 of door 5 to pillar 7, the pillar 7 also serving as a support for windshield 8 and cab roof 9. 
     The rear perimeter 10 of door 5 abuts bulkhead 11 of truck cab 1. Immediately, adjacent into the rear of bulkhead 11 is the truck bed or &#34;box&#34; 12 which includes a left side wall 13 having a top rail 14. 
     The cab fairing of the present invention is shown generally at 15. Although the fairing may take a variety of specific forms, the fairing 15 would generally include a central bar 16 which spans the portion of fairing 15 between left panel 17 and right panel 18. As seen in FIG. 2, a preferred embodiment may be symmetrical with respect to a vertical axis 19, but this does not necessarily have to be the case. Also observable in FIG. 2 is the relatively small frontal area of fairing 15, thereby projecting a relatively low profile surface to be encountered by the relative wind passing over truck cab 1. 
     As seen in FIG. 3, left side wall 13 of truck bed 12 resides beneath the lower portion of left side wall 17. Left lip 20 projects vertically below the surface level of top rail 14, thereby providing additional protection from wind, rain and dust entering the truck bed 12. Due to the symmetry of fairing 15, a similar structure exists on the right hand side of the truck with right top rail 21 residing beneath right lip 22, with right lip 22 projecting somewhat below the horizontal surface of right rail top 23 of right side wall 21. A small gap exists between the bottom of right panel 18 and the top of right rail 23 of right side wall 21, the distance of the gap not being critical and typically varying between 1/8 of an inch and 3 inches. The length of the lip 22 should in most cases be sufficient to overlap side wall 21, and in the preferred embodiment could have a length varying between 1/2 inch and 31/2 inches. 
     Referring particularly to FIGS. 1 and 4, the right side wall 18 of fairing 15 is shown. The fairing 15 is affixed to cab roof 9 by means of mounting hole 24. A series of mounting holes 25, 26 and 27 are used to secure right side wall 18 to cab 1 in the region behind door 5. An additional mounting hole 28 secures a strut (not shown) which is connected to the cab so as to stabilize and prevent vibration of fairing 15. As best seen in FIG. 4, Inlets 29, 30 and 31 are formed within sidewall 18. The particular contours of inlets 29, 30 and 31 maybe chosen to satisfy aesthetic or decorative purposes, but the inlets also serve a useful function in preventing vibration of fairing 15. When the vehicle is in motion, air passing over right side wall 18 produces an area of low pressure over the outer surface of side wall 18, much as air passing over an aircraft wing creates an area of low pressure, since the air passing over the outer surface travels at a relatively high velocity whereas the air passing over the inner surface travels at a relatively low velocity. This low pressure force would tend to pull right side wall 18 away from the truck, that is, to &#34;Bow out&#34;, the amount of force being proportional to the speed of the truck. In order to reduce this tendency, inlets 29, 30 and 31 cause air to press inwardly against inlet side walls 32, 33, 34, 35, 36 and 37, thereby producing a reaction force which presses the entire right side wall 18 inwardly. 
     Front edge 38 of right side wall 18 is formed so as to follow the contour of the rear surface of the truck cab 1, that is, to provide a shape which will permit mounting of fairing 15 but without interfering with the opening and closing of door 5. Typically, this would require that front wall 38 be substantially vertical. Rear wall 39 may be of any shape, but typically will slope at an approximate 45° angle towards the rear of the vehicle, terminating at lower lip 22. Typically, left side wall 17 is formed in a similar fashion. 
     Referring particularly to FIG. 5, other aerodynamic and structural features of the fairing 15 may be observed. Central bar 16 is seen to include several surface contours, including a forward ramped portion 40, a substantially horizontal surface 41, a ramped transition area 42 and a rear platform 43. Since central bar 16 would tend to act as an air foil, creating lift, as the vehicle moves forward, ramped surface 40 and transition surface 42 tend to create a downward reaction force in response to the force of the air deflecting from them. Substantially horizontal surface 41 serves as a mounting area for accessories such as horns, lights and antennas. Rear platform 43 may be extended rearwardly as far as desired, serving to extend the surface area of cab roof 9 and thereby providing additional protection for box 12 (not shown). 
     The manner in which the central bar 16 is fastened to side wall 17 and 18 is best seen by referring to FIG. 6, 9 and 10. In order to simplify the field installation process, side wall 17 and 18 would first be mounted to truck cab 1. As seen in FIG. 9, left side wall 17 is temporarily held in place by tape segments 57 and 58, thereby permitting drilling of holes in cab 1 to align with mounting holes 24, 25, 26 and 27. A similar process is performed with right sidewall 18. Central Bar 16, which is formed as a separate piece, would then be fitted into position and bolted into place. In the preferred embodiment, 41/4 inch by 1 inch bolts are used as fasteners. Bolts 44 and 45 are used to fasten central bar 16 to left side wall 17, whereas bolts 46 and 47 are used to fasten central bar 16 to right side wall 18. In order to reinforce central bar 16, particularly when used as a light bar or horn support, a center support bracket 52 may be employed. A bottom end 53 of bracket 52 is fastened to cab roof 9 by means of bolt 54, whereas top end 55 of bracket 53 is affixed to a suitable mounting hole (not shown) in central bar 16 by means of bolt 56. 
     Referring particularly to FIGS. 7 and 8, the stabilizing arrangement utilized in the present invention can best be seen. In order to preserve the small gap 59 between, for example, right panel 18 and right side rail 21, a direct connection between right panel 18 and right side wall 21 is not possible. Since right panel 18 presents a relatively large surface exposed to the relative wind as the truck moves forward, some means of stabilizing or reinforcing right panel 18 is necessary. In the preferred embodiment, a strut or bracket 48 is rigidly affixed to right panel 18 and the rear surface 49 of truck cab 1. Bracket 48 may be formed in a variety of ways, but typically is a flat bar having a panel end 50 and a cab end 51. Each end 50 and 51 is bent so that it resides in a plane that is substantially parallel to the surface to which it is attached. A mounting hole is drilled in each end, with a hole in panel end 50 being aligned with mounting hole 28 in right panel 18. A mounting hole is drilled in rear surface 49 of truck cab 1 so as to align with a hole in cab end 51. In the preferred embodiment a 3/16 inch by 5/8 inch hex head bolt and &#34;kep&#34; nut is provided to fasten the panel end 50 of bracket 48 to right panel 18. A 1/4 inch by 3/4 inch self tapping bolt is used to fasten cab end 51 to rear surface 49. 
     Those skilled in the art will undoubtedly appreciate the various modifications and additions that may be made in the method and apparatus of the present invention without departing from the central features of novelty thereof, which are intended to be defined and secured by the appended claims.

Technology Classification (CPC): 1