Abstract:
A tailgate lift assistor that provides for a reduced force required to rotate or pivot a tailgate of a pickup truck or the like upwardly from a generally horizontal open position to a generally vertical closed position and in one embodiment the lift assistor is combined with a dampening mechanism that dampens the opening of the tailgate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This Application claims priority of U.S. Provisional Patent Application Ser. No. 61/024,744 filed on Jan. 30, 2008. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention is directed to device for assisting in the movement of the tailgate of a truck or the like from an open to a closed position and more particularly in one embodiment of the invention to such an assistor combined with a dampener for damping movement of the tailgate from an upper to a lower position 
       BACKGROUND OF THE INVENTION 
       [0003]    Pick-up trucks typically have a tailgate that prevents material, objects, etc. from escaping from the bed of the truck when in the closed position. The tailgate is typically opened using a hand latch that allows the tailgate to swing in a downward position and provide horizontal access to the bed. Once the tailgate is lowered to a generally horizontal position, lifting of the tailgate to its former upright position requires physical exertion. This physical exertion can be difficult for an individual depending upon their physical capability. Therefore, a tailgate lift assistor would be desirable. In addition, most tailgates have a restraining mechanism that prevents the tailgate from lowering below the horizontal position. However, these mechanisms typically do not prevent the tailgate from opening in a free fall fashion and coming to an abrupt stop when the restraining mechanism has permitted the tailgate to reach a permitted lower position. The opening of the tailgate in such a free fall fashion can damage and wear relevant parts associated with the tailgate as well as the restraining mechanism itself. Therefore, including a tailgate opening dampening mechanism in combination with a lift assistor would also be desirable. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention includes a tailgate lift assistor that provides for a reduced force required to rotate or pivot a tailgate from a generally horizontal position up to a generally vertical position. As such, the present invention has utility as a tailgate component. In addition, the tailgate lift assistor can be combined with a dampening mechanism that dampens the opening of a tailgate on a pick-up truck. 
         [0005]    The tailgate lift assistor includes a torsion rod that is placed under torsional stress during the lowering of the tailgate from an upright position to a down position. The torsion rod is provided with a tab, lever, catch, and the like that exerts a generally upward force on the tailgate when the tailgate is in the down position. The generally upward force on the tailgate thereby reduces the force required to pivot, or sometimes referred as to “lift”, the tailgate from the generally horizontal position to the generally upright position. If included, the dampening mechanism includes a housing with a tailgate shaft and a dampening device that applies resistance to the rotation of the tailgate shaft. The tailgate shaft can be fixedly attached to the tailgate with resistance on the shaft providing a smooth and controlled opening and closing of the tailgate. In some instances, the torsion rod can be attached in series with the dampening mechanism. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    A better understanding of the present invention can be had upon reference to the following drawings in which; 
           [0007]      FIG. 1  is a fragmentary perspective view of a pickup truck illustrating a tailgate suitable for use with the present invention; 
           [0008]      FIG. 2  is a fragmentary perspective view partially in section of an embodiment of the present invention; 
           [0009]      FIG. 2A  is a fragmentary cross sectional view of the torsion rod of the tailgate assistor of the present invention; 
           [0010]      FIG. 3  is a diagrammatic view of a portion of the structure of the tailgate assistor of the present invention illustrating the tail gate in an upper, closed position; 
           [0011]      FIG. 4  diagrammatic view similar to  FIG. 3  but illustrating the position of the tailgate assistor when tail gate is moved to a position between a closed position and an open position; 
           [0012]      FIG. 5  is a diagrammatic view similar to  FIG. 3  but illustrating the position of the tail gate assistor when tail gate in a lower open position; 
           [0013]      FIG. 6  is a view similar to  FIG. 2  but illustrating another preferred embodiment of the present invention; 
           [0014]      FIG. 7  is an exploded perspective view of the tailgate dampening mechanism of the present invention; 
           [0015]      FIG. 8  is an end elevational view of the housing shown in  FIG. 7 ; 
           [0016]      FIG. 9  is a at op elevational view of the shaft insert shown in  FIG. 7 ; 
           [0017]      FIG. 10  is diagrammatic view illustrating the damping effect provided by the dampener mechanism; 
           [0018]      FIG. 11  is a cross-sectional view of another dampener of the present invention; and 
           [0019]      FIG. 12  is a cross-sectional view taken substantially along line  12 - 12  of  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    Referring now to  FIG. 1 , a bed  10  and a tailgate  20  of a pick-up truck are shown. The tailgate  20  can be pivotally attached by conventional means to the pick-up truck proximate the bed floor  12  of the bed  10 . The tailgate  20  is shown in the lower open position in  FIG. 1 . 
         [0021]    Turning now to  FIG. 2 , a larger view of the tailgate  20  is shown wherein an embodiment of the present invention is illustrated. The embodiment includes a torsion spring  100  that is located at least partially within the tailgate  20 . In some instances, the torsion spring  100  can be in the form of a torsion rod  110  extending through the tailgate  20 . The rod  110  includes a first end  130  and a second end  140 . The first end  130  can be inserted within an aperture (not shown) of one of the sidewalls  14  of the bed  20  and be operable to rotate within said aperture. In contrast, the second end  140  is a fixedly attached to another sidewall  14  of the bed  20  and thus, does not rotate. Attached to the torsion rod  110  is a tab or lever  120 . 
         [0022]    As can best be seen in  FIG. 2A  the torsion rod  110  is of conventional construction with mating tubes  110   a  and  110   b  mounted to axially separately rotate and joined by an internal spring  110   c  which resists relative axial movement between the tubes  110   a  and  110   b.  The end  140  of tube  110   b  is fixed to the sidewall  14  and the end  130  of the tube  110   a  is free to axially rotate with respect to the sidewall  14  resisted only by the spring  110   c.  The tab  120  is attached to the tube  110   a  of torsion rod  110 . 
         [0023]    Turning now to  FIGS. 3-5 , a housing  150  not shown in  FIG. 2  can be present as part of and/or within the tailgate  20  with the tab  120  of the torsion spring  100  located at least partially within the housing  150 . The housing  150  can have a first side  152  and a second side  154 . The housing  150  is fixedly attached to the tailgate  20  such that when the tailgate  20  pivots in the first direction  1 , ( FIG. 4 ) so does the housing  150 . Thus, as illustrated in  FIG. 4 , with the tailgate  20  moving in the first direction l,from the upper closed position of the tailgate  20  shown in  FIG. 3  the second side  154  of the housing  150  will eventually come into contact with the tab  120 . Upon further rotation of the tailgate  20  in first direction  1 , for example when the tailgate  20  is lowered to a lower open position as illustrated in  FIG. 5 , the second side  154  applies force to the tab  120 , thereby causing the tab  120  and the tube  110   a  of the torsion rod  110  to rotate in the first direction  1 , as shown in  FIG. 5 . Rotation of the torsion rod  110  against the bias of the spring  110   c  ( FIG. 2   a ) creates an opposite force upon the second surface  154  in the second direction  2 . It is appreciated that the force applied by the tab  120  upon the second surface  154  is such that the tailgate  20  can be lowered to the down position and will remain there until lifted by an individual. It is also appreciated that upon lifting of the tailgate  20  by an individual, the force of the tab  120  on the second surface  154  will result in a reduced force required by an individual to move the tailgate from the generally horizontal position. It is still yet appreciated that the resistance applied to the second surface  154  by the tab  120  when the tailgate  20  is being moved from an upright position to a down position can provide a dampening effect to the lowering of the tailgate. Although illustrated as a spring biased torsion rod  110  the necessary rotational bias could also be in the form of a wound spring, a hydraulic cylinder, and the like. 
         [0024]    In some instances, the torsion rod  110  can be connected in series with a tailgate shaft dampening mechanism  200  as illustrated in  FIG. 6 . As best seen in  FIG. 7  the dampening mechanism  200  preferably includes a housing  210  and a shaft insert  220 . The housing  210  can have a mount plate  215  and a cavity region  217 . The shaft insert  220  includes a tailgate shaft  222 , a paddle surface  224 , a housing shaft  226  and a flat surface  228 . The shaft insert  220  can be inserted within the cavity region  217  of the housing  210  such that the tailgate shaft  222  extends therefrom. The tailgate shaft  222  is freely rotatably mounted in the sidewall  14  opposite the end  140  of the torsion rod  110 . 
         [0025]    Within the cavity region  217  of the housing  210  are divider plates  212  ( FIG. 8 ) providing a first chamber  214  and a second chamber  216 . As can best be seen in  FIG. 7  the tailgate shaft  222  extends from a bottom region of the shaft insert  220  and the housing shaft  226  extends from a top region. The top region includes the paddle surface  224  and two flat surfaces  228  ( FIG. 9 ) adjoining the bottom region and the top region. 
         [0026]    Referring now to  FIG. 10 , the dampening mechanism  200  is shown in an assembled condition. with the shaft insert mounted within the housing  210 . As shown in the drawing, the paddle surface  224  and the housing shaft  226  fit between the two dividers  212 . A clearance  230  is provided between the inside surface of the cavity region  217  and the paddle surface  224 . In addition, one of the dividers  212  includes a one-way valve  219 . 
         [0027]    Upon insertion of the shaft insert  220  within the housing  210 , a viscous fluid is provided within the cavity region  217 . The viscous fluid (not shown) prevents an unrestrained rotation of the shaft insert  220 . In addition, the clearance  230  between the paddle surface  224  and the inner surface of the cavity region  217  affords for a desired restrained rotation of the shaft insert  220 . 
         [0028]    In operation, the tailgate shaft  222  is fixedly attached to the first end  130  of the torsion rod  110 . Upon lowering of the tailgate  20  from the closed position to the open position, the shaft insert  220  rotates in a clockwise or counter-clockwise position depending upon the location of the dampening mechanism  200 . Upon rotation of the shaft insert  220 , the viscous fluid within the first chamber  214  and second chamber  216  resists the movement of the paddle surface  224 . However, the clearance  230  between the paddle surface  224  and the inner surface of the cavity region  217  affords a restrained rotation of the shaft insert  220  and therefore a restrained lowering of the tailgate  20  from the closed position to the open position. Upon closing the tailgate from the open position to the closed position, the one-way valve  219  affords for the flow of the viscous fluid between the first chamber  214  and the second chamber  216 . By allowing the flow of the viscous fluid between the two chambers, the extent or magnitude of the restraint on rotation of the shaft insert  220  experienced during the raising of the tailgate  20  is not experienced. In addition, the torsion spring  100  provides a decrease in the force required to lift the tailgate from the generally horizontal position. In this manner, the tailgate  20  can be closed in a timely manner without excessive force. It is appreciated that the housing  210  with the shaft insert  220  inserted therein is mounted on the sidewall of the bed  210  in such a location to afford for the proper mounting of the tailgate  20  onto the pick-up truck. 
         [0029]    Turning now to  FIGS. 11 and 12 , another embodiment of a shaft dampening mechanism is illustrated at reference numeral  300 . The shaft dampening mechanism  300  can include a housing  310  and a shaft  320 . The housing  310  can include a mounting plate  315  and a cavity region  317 . The shaft  320  has a tailgate end  322  and a housing end  324 . The tailgate end  322  can be fixedly attached to the first end  130  of the torsion spring  100 . It is appreciated that the tailgate end  322  of the shaft  320  and the first end  130  of the torsion spring  100  can be attached with a clutch mechanism that provides a desired slippage therebetween. 
         [0030]    The housing end  324  is dimensioned such that it can be received by the cavity region  317 . An optional bearing  326  can be included to afford for improved rotation of the shaft  320 . The shaft  320  also includes a shaft plane  325  that extends in a radial direction from the shaft  320 . Extending from the shaft plate  325  is a torsion spring lever  323 . The torsion spring  330  is provided and can be attached to the shaft  320  and the torsion spring lever  323  as illustrated in  FIG. 12 . When attached to the shaft  320  and lever  323 , the torsion spring  330  affords restraint on the rotation of the shaft  320 . As observed in  FIG. 12 , the torsion spring  330  would afford restraint on the counter-clockwise rotation of the shaft  320 . 
         [0031]    Optionally included is at least one shear plate  340  which can be located adjacent to the shaft plate  325 . A clearance  342  is provided between the shear plate  340  and the shaft plate  325 . In addition, a plurality of shear plates  325  can be provided with the clearance  342  included therebetween. Within the cavity region  317  a fluid reservoir  312  can be provided wherein a viscous fluid can be contained. In addition, a seal  350  can be included such that the viscous fluid does not leak from the reservoir region  312 . Upon rotation of the shaft  320  with the shear plate  340  attached thereto the viscous fluid can restrain the rotation. 
         [0032]    In operation, the restraint on the rotation of the shaft  320  and thus the tailgate  20  can be afforded by a combination of the torsion spring  330  and the shear plate  340  with viscous fluid between shaft plate  325  and shear plate  340 . In this manner, dampening of the lowering of the tailgate  20  is provided. In additional, attachment of the torsion spring  100  to the shaft dampening mechanism  200  and/or  300  affords for a generally upward force to be applied to the tailgate when said tailgate is in the generally lowered horizontal position. Therefore, less force is required by an individual to raise the tailgate  20  from the horizontal position and into the upright position. It is appreciated that the length, diameter, shape, material, and the like of the torsion spring  100  can be adjusted and/or altered such that a desired upward force on the tailgate  20  is applied. 
         [0033]    It is also appreciated that the present invention includes any type of shaft rotation dampening mechanism and/or tailgate lift assistor wherein a shaft fixedly attached to a tailgate experiences a desired restrained rotation and/or desired upward force as the tailgate is moved from the closed position to the open position and then from the open position to the closed position, respectively. The various components of the tailgate lift assistor and/or the shaft dampening mechanism can be made from any material known to those skilled in the art, illustratively including metals, alloys, plastics, ceramics, and combinations thereof. The viscous fluid can include any fluid having suitable viscosity, illustratively including water, oil and other organic and/or non-organic fluids. 
         [0034]    The foregoing drawings, discussion and description are illustrative of specific embodiments of the present invention, but they are not meant to be limitations upon the practice thereof. Numerous modifications and variations of the invention will be readily apparent to those of skill in the art in view of the teaching presented herein. It is the following claims, including all equivalents, which define the scope of the invention.