Abstract:
Apparatus are provided which utilize the tailgate of a vehicle, such as a pick-up truck, to create an aerodynamic windspoiler for the vehicle. In one form, the apparatus includes a housing is pivotally attached to the vehicle, and a rod having a first end supported within the housing and a second end attached to the tailgate, wherein the rod is capable of being slidably extended and retracted from the housing. Ideally, the positioning of the rod relative to the housing is controlled relative to the speed of the vehicle to adjust the inclination of the tailgate. This may be accomplished utilizing either an electrically driven motor or an hydraulic cylinder. In another form, the apparatus includes a rotatable shaft attached to a sheet of stretch resistant material. Upon extending and attaching the sheet of material to the tailgate, a windspoil is created.

Description:
RELATED APPLICATION 
     This application claims priority from provisional application Ser. No. 60/074,452 filed Feb. 12, 1998 and provisional application Ser. No. 60/084,713 filed May 8, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to pick-up trucks and like vehicles which have an open bed and a tailgate. More particularly, the present invention relates to utilizing a conventional tailgate to act as an aerodynamic spoiler to reduce wind drag. 
     By virtue of its very design, pick-up trucks are aerodynamically inefficient. This is due, in large part, to the open bed of the truck which is closed off by a tailgate. Ambient airstreams flow relatively smoothly over the cab down into the bed of the truck, however, the airstream makes an abrupt transition from horizontal flow over the truck bed to a vertical flow when encountering the tailgate. Without a gradual redirection of the airstream, a tremendous amount of drag occurs. This drag increases fuel consumption and reduces available horsepower and vehicle performance. Although wind drag occurs at all speeds, the negative effects become more pronounced as vehicle speed increases. 
     Attempts have been made to remedy or at least alleviate this problem. These attempts can be classified into two areas, namely reconfiguration of the truck bed and reconfiguration of the tailgate. 
     Pick-up truck owners have reconfigured the truck bed by placing a cover over the bed. There are many forms of covers. Some are elevated, making the truck cab and bed into what appears to be a single unit. Other covers are placed over only the bed of the truck. These are oftentimes referred to as tonneaus. Tonneaus may be hard or soft and are usually secured to the upper edge of the truck bed. Although at least partially effective at reducing wind drag, these truck bed covers make it difficult to use the pick-up in its intended manner. Typically, objects are constantly being inserted into and removed from the truck bed, requiring removal of the cover before use. However, removal of the cover eliminates the wind drag reduction benefits. The tonneau must also be stored when removed and then re-secured after the objects are taken out of the truck bed. This practice has been found to be very inconvenient. 
     Other devices have been developed which modify or replace the tailgate itself. Some devices require the manual repositioning or removal of the tailgate and are typically quite cumbersome. Another device mounts spoilers atop the tailgate to direct wind flow. However, this device does not resolve the problem of the drag encountered at the face of the closed tailgate within the bed of the truck. Other devices replace the conventional tailgate with a fabric mesh or pivotal wings. However, these devices drastically alter the appearance of the truck and can also adversely affect the ability to transport items in the bed of the truck. 
     Thus, what is needed is a device which allows a truck owner to reduce tailgate wind drag without having to manually remove a cover or tailgate. Further, a device is needed which reduces wind drag while allowing the truck owner to conveniently place objects in and out of the truck bed. Additionally, a device is needed which utilizes the original equipment manufactured tailgate of the truck, thus retaining the overall look of the truck. The present invention fulfills these needs and provides other related advantages. 
     SUMMARY OF THE INVENTION 
     The present invention resides in apparatus which utilize the tailgate of a vehicle, such as a pick-up truck, to create an aerodynamic windspoiler for the vehicle. In one form, the apparatus comprises, generally, a housing which is attached to the vehicle, a rod having a first end supported within the housing and a second end attached to the tailgate, wherein the rod is capable of being slidably extended and retracted from the housing, and means for controlling the positioning of the rod relative to the housing in relation to the speed of the vehicle. 
     In one illustrated embodiment, the housing is pivotally attached to the vehicle and the rod is pivotally attached to the tailgate by a pivotal joint. The controlling means comprises an electrically driven motor. The electrically driven motor may be manually actuated or activated by a speed sensing logic control unit. 
     In another illustrated embodiment, the housing is pivotally attached to the vehicle and the rod is pivotally and removably attached to the tailgate by a pivotal joint. The controlling means comprises an hydraulic cylinder and spring assembly associated with the housing. The spring normally biases the rod towards the housing, but permits the rod to extend in response to ambient air-flow over the tailgate as the speed of the vehicle increases. 
     In another form of the invention, the apparatus includes, generally, a rotatable shaft attached to a sheet of stretch resistant material which is extendable and retractable from the shaft. A first end of the sheet is attached to the shaft and a second end of the sheet is removably attachable to the tailgate. Upon extending and attaching the sheet of material to the tailgate, a windspoil is created. The sheet has a width substantially the width of the bed of the vehicle and is typically attached to the tailgate with clamps. The shaft may be coupled to a torsional spring which biases the shaft so that the sheet of material is normally wrapped around the shaft when not attached to the tailgate. The shaft is usually attached to the vehicle between the cab portion and wheel wells by frictionally lodging the shaft between opposing bed walls of the vehicle. The apparatus may also include a housing which envelopes the shaft and torsion spring and may be lodged between the walls of the cab. The housing includes a longitudinal aperture through which the sheet passes as it is extended from and retracted back onto the shaft. 
    
    
     Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings illustrate the invention. In such drawings: 
     FIG. 1 is a partial perspective view of the bed of a pick-up truck, illustrating the drag created when wind abruptly encounters a closed tailgate; 
     FIG. 2 is a perspective view similar to FIG. 1, illustrating the spoil effect generated when the tailgate is partially opened; 
     FIG. 3 is a perspective view similar to FIG. 1, showing an hydraulic cylinder apparatus attached to a vehicle and having an extendable rod attached to a closed tailgate; 
     FIG. 4 is a perspective view similar to FIG. 2, illustrating the rod of the hydraulic cylinder apparatus of FIG. 3 in an extended position; 
     FIG. 5 is an enlarged, partially cross-sectional view of the hydraulic cylinder apparatus of FIG. 4, showing pins for setting the position of the rod relative to the apparatus; 
     FIG. 6 is a partial perspective view similar to FIGS.  1  and  3 , showing a motorized apparatus attached to a vehicle and having an extendable rod attached to a closed tailgate; 
     FIG. 7 is a perspective view similar to FIGS. 2 and 4, illustrating the rod of the motorized apparatus of FIG. 6 in an extended position; 
     FIG. 8 is an enlarged view of the motorized apparatus of FIG. 7; and 
     FIG. 9 is a partial perspective view similar to FIGS. 1,  3  and  6 , showing a windspoiler apparatus lodged between opposing walls of the vehicle bed and having a sheet attached to the tailgate. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in the drawings for purposes of illustration, the present invention is concerned with an apparatus which is interconnected between a vehicle  10  and a tailgate  12 , creating a windspoil which reduces wind drag. As shown in FIG. 1, ambient wind created by movement of the vehicle passes over the cab portion of the vehicle and smoothly transitions into the bed  14  of the vehicle. Upon encountering the tailgate  12 , the wind faces an abrupt vertical transition. This abrupt transition creates wind drag which adversely affects vehicle performance. However, when the tailgate  12  is partially opened, as shown in FIG. 2, a windspoil is created and the wind is able to make a smoother transition between the cab  14  and the tailgate  12  which reduces wind drag. 
     In accordance with the invention, and as illustrated in FIGS. 3-8, the apparatus  16  is comprised, generally, of a housing  18  which is attached to the vehicle  10 , an extendable and retractable rod  22  having a first end  24  supported within the housing  18  and a second end  26  removably attached to the tailgate  12 . Additionally, means for controlling the positioning of the rod  22  relative to the housing  18  in relation to the speed of the vehicle  10  is also provided and is typically associated with the housing  18 . The housing  18  may be pivotally attached to the vehicle  10  by a swivel bracket  20 , and the rod  22  may be attached to the tailgate  12  via a pivotal joint  28  in order to allow the tailgate  12  to open and close in response to the extension and retraction of the rod  22 . 
     The apparatus is attached to the vehicle  10  and tailgate  12  by removing the originally equipment manufactured (OEM) latch bolts and strike plates from the tailgate jams as well as the opening latch mechanism and one hinge. Both OEM pivots and one hinge are retained, unaltered. If the apparatus  16  is placed behind a stake post housing  30 , an adequate aperture  32  must be created in the stake post housing  30  to allow the rod  22  to fully pivot. The swivel bracket  20  is attached to one of the vertical cargo bed walls  34  through which the housing  18  is inserted and secured. Enough clearance is left to enable the housing  18  to pivot within the bracket  20  without coming into contact with obstructions of the cab wall  34 . The rod  22  extends out from the housing  18  and through the aperture  32  created in the stake post housing  30 . The rod  20  is attached to the pivotal joint  28  which has been attached to a predetermined site on the tailgate  12 . 
     As vehicle speed increases, the wind drag caused by the ambient wind flow through the bed  14  of the vehicle  10  also increases. To counteract this effect, the rod  22  is extended from the housing  18  and the tailgate  12  is lowered, allowing the wind to flow out of the cab  14  more easily. 
     One illustrated form of the invention, as shown in FIGS. 3-5, utilizes a damped mechanical device  16  shown, for illustrative purposes, as an hydraulic fluid damped, spring biased cylinder which forms the housing  18  to open and close the tailgate  12 . Attached to the first end  24  of the rod  22  is a piston  36  within the hydraulic cylinder. As vehicle speed increases, the force exerted on the tailgate  12  by the ambient wind increases. This force causes the rod  22  to extend from the housing  18  and allows the tailgate  12  to open partially. As the vehicle speed increases, the force from the wind increases and the rod  22  continues to extend from the housing  18 . However, due to the compression of the spring, in the hydraulic cylinder, the rod  22  is normally biased towards the housing  18 . Therefore, as the rod  22  extends the piston  36  within the hydraulic cylinder increasingly compresses the spring within the housing  18  causing the extension of the rod  22  to be increasingly resistive. The tailgate  12  remains open until the vehicle speed and wind force are reduced and the rod  22  is then retracted into the housing  18  by the compression of the hydraulic cylinder until the tailgate  12  is fully closed. 
     A cable  38  may be interconnected between the vehicle  10  and the tailgate  12  to ensure that the tailgate  12  is not allowed to fully open. The cable  38  may be attached to a fastener of the tailgate  12 . The cable  38  and the rod  22  may be removed from the tailgate  12  and the pivotal joint  28 , respectively, in order to either fully open or even remove the tailgate  12  in order to load or unload objects from the bed  14  of the vehicle  10 . The rod  22  may have apertures  40  through which pins  42  can be inserted in order to the tailgate  12  at a predetermined angle or held in a closed position. Typically, the pins  42  come into contact with an obstruction, such as the stake post housing  30 , which impedes further extension of the rod  22 , thus holding the tailgate  12  in place. 
     Another form of the present invention is illustrated in FIGS. 6-8. The housing  18  of this apparatus  16 ′ is associated with an electric motor  44 , preferably a gear head type, which is able to extend and retract the rod  22 . The motor is preferably connected to the electrical system of the vehicle  10 . The motor  44  can be activated manually by an electric switch, such as a toggle switch positioned in the cab of the vehicle, or a remote transmitter switch, such as a key chain radio transmitter. Using the switch, the operator of the vehicle  10  can lower the tailgate  12  to whatever angle is desired at any given speed. This is particularly useful when loading and unloading the bed  14  of the vehicle  10  as the tailgate  12  can be fully opened without disconnecting the rod  22  from the tailgate  12 . The ability to fully open the tailgate  12  is useful while in reverse as the user is able to view small children or other obstructions which would otherwise not be visible. The tailgate  12  may also be locked in not only completely open or closed positions, but at any partially opened position. 
     The electric motor  44  may also be controlled automatically with a logic control circuit designed to discriminate differing vehicle speeds. The logic control circuit  72  is designed to discriminate two velocities, one for deployment and the other for retraction. The logic control circuit  72  can tap into the vehicle&#39;s existing computer to obtain the speed of the vehicle  10 , or can be in circuit with a vehicle speed sensor. Speed sensors are typically comprised of a small magnet trigger affixed to the drive shaft of the vehicle and associated with a receiver placed in proximity of the trigger so as to induce an electromagnetic pulse. This signal is relayed to the logic circuit and vehicle speed is determined. When the vehicle  10  attains predetermined speeds, a relay is tripped and a voltage is supplied to the motor for desired action. The control circuit  72  employs both linear and digital integrated circuit devices addressing multiple function, safety, and product reliability concerns. 
     The motor  44  may be actuated to extend or retract the rod  22  at a given predetermined speed, or incrementally extend or retract the rod  22  at various predetermined speeds. These speeds do not need to be the same value. For example, at 48 m.p.h. the motor  44  may be activated to extend the rod  22  which lowers the tailgate  12  to a predetermined angle, for example 60°; once the vehicle slows to 35 m.p.h. the motor  44  would be activated to retract the rod  22  which would close the tailgate  12 . A redundant system may be employed to prevent unwanted closure of the opened tailgate  12  during vehicle operation in order to protect items placed in the vehicle  10  which are longer than the bed  14 . The tailgate  12  can be locked in a closed position to prevent transported items from falling out of the vehicle as well. 
     The apparatus electronic control allows the user to fully open the tailgate  12  while backing up to view small children or obstructions. 
     FIG. 9 illustrates yet another form of the invention wherein an apparatus  46  is comprised, generally, of a rotatable shaft  52  connected to the vehicle  10  and a sheet  64  of stretch resistant material attached at one end to the shaft  52  and removably attachable to the tailgate  12  at another end. The sheet  64  is extendable from and retractable to the rotatable shaft  52 . The shaft  52  may be coupled with a torsion spring  54  which acts to wind the sheet  64  around the shaft  52 . A housing  48  having an aperture  50  substantially along its axis may envelope the shaft  52  and torsion spring  54 . 
     The sheet  64  of stretch resistant material may have a width approximately equal to the width of the bed  14  of the vehicle  10 . The sheet  64  is manually extendable from the housing aperture  50  and typically attached to the tailgate  12  with clamps  70 , such as hood clamps. A rod may be attached to the sheet  64  to facilitate removal from the housing  48  and also to give stability to the attachment of the sheet  64  to the tailgate  12 . When the sheet  64  is removed from the tailgate  12 , the tensioned torsion spring  54  releases causing the shaft  52  to rotate and the sheet  64  to be rewound about the shaft  52 . 
     The housing  48  may include threaded female ends  56  which are engaged with threaded male shafts  58  having rubber mounting shoes  60 . The male shafts  58  have opposite right and left hand threads. The housing  48  is preferably secured to the vehicle  10  toward the front cab portion of the wheel wells  62  by rotating the cylindrical housing  48  which causes the oppositely threaded male shafts  58  to rotate outwardly and the rubber mounting shoes  60  to come into contact with opposite bed walls  34 , frictionally holding the housing  46  in place. 
     By attaching the sheet  64  to the tailgate  12 , a windspoil is created which results in a smooth wind flow transition between the bed  14  of the vehicle  10  and the tailgate  12 . The windspoil is easily removed by detaching the sheet  64  from the tailgate  12  and allowing the sheet  64  to retract into the housing  48  by scrolling onto the central shaft  52 . The entire apparatus  46  may be removed from the vehicle  10  by rotating the cylindrical housing  48  such that the rubber mounting shoes  60  become dislodged from the vehicle bed walls  34 . 
     The present invention allows a vehicle owner to create a windspoil which reduces vehicle inefficiency due to wind drag. The windspoil may be manually or automatically adjusted to varying vehicle created wind speeds while allowing the vehicle owner to lock the tailgate  12  shut or completely open the tailgate  12 . This control allows the owner to easily place objects into and out of the bed  14  of the vehicle  10  without removing the apparatus. One of the most important aspects of the present invention is that it accomplishes the above results while retaining the OEM tailgate  12 , and thus the original look of the vehicle. 
     Although several embodiments have been described in detail for purposes of illustration, various modifications may be made without departing from the scope and spirit of the invention. Accordingly, the invention is not to be limited, except as by the appended claims.