Abstract:
A lift gate assembly particularly adapted for use in a vehicle having a side opening. The assembly includes a platform that folds and pivots to the interior of the vehicle when in a stored mode. When deployed, the platform pivots to the exterior of the vehicle and unfolds. A telescoping column allows movement of the unfolded platform between upper and lower levels. Movement of the platform may be accomplished by employing hydraulic means.

Description:
BACKGROUND OF THE INVENTION 
     This application is a continuation of Ser. No. 09/491,887 filed Jan. 24, 2000. This application claims the benefit of U.S. Provisional Application, Ser. No. 60/156,789, filed on Sep. 30, 1999, in Express Mail Label No. EL359134972US by the same inventors, Ken Rock and Andy Grow, entitled SIDE DOOR LIFT GATE. 
     This invention pertains to methods and apparatuses for lift gates, and more specifically to methods and apparatuses for a lift gate provided on the side of a vehicle. 
    
    
     DESCRIPTION OF THE RELATED ART 
     Lift gates for lifting objects into and out of vehicles are relatively well known. Typically, these lift gates are hydraulically operated and are mounted at the rear of a large vehicle such as a tractor-trailer. The lift gates allow objects to be easily loaded into the vehicle and unloaded from the vehicle by raising and lowering the objects. 
     Some side-door lifting apparatuses have been contemplated in the prior art. For example, U.S. Pat. No. 4,479,753 to Thorley discloses a retrofittable wheelchair lift for passenger vehicles. The lift assembly is hinged on a vertical axis to a door post adjacent the door hinge. When the door opens, the lift assembly pivots away from the door opening. A horizontal carrier slides further outwardly so that the lift assembly clears the side of the vehicle. A single telescoping vertical carrier is deployed by a hydraulic actuator to lower a platform which then rotates away from the vertical carrier along a horizontal hinge located at the lower edge of the vertical carrier. This lifting apparatus requires a horizontal carrier to ensure clearance of the platform from the side of the vehicle. Also, this lifting apparatus is mounted onto the door of the vehicle which restricts both the weight of lifting apparatus and the amount of weight that can be lifted. 
     U.S. Pat. No. 4,456,421 to Robson discloses a lifting apparatus carried in an inoperative compact form within the interior of a vehicle and deployed in an operative position outside the vehicle. A pillar is provided in the interior of the vehicle near either a side or rear door. The disclosed lifting apparatus utilizes a parallelogram linkage to raise and lower the platform. This lifting apparatus is directed to the lifting of wheelchairs. Again, this design restricts the amount of weight that can be lifted. 
     The present invention contemplates a new and improved lift gate construction which is simple in design, effective in use, and overcomes the foregoing difficulties and others while providing better and more advantageous overall results. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention a lift gate is provided which is associated along the side of a vehicle. For instance, the lift gate may be located anywhere along the side of a tractor-trailer. 
     According to another aspect of the current invention, the lift gate folds so as to be recessable within the side of the vehicle. 
     According to another aspect of the current invention, the side lift gate has a platform operatively connected to a telescopic column. The column allows the platform to be raised and lowered so that objects may be loaded into and out of the side of the vehicle. 
     According to another aspect of the invention, a lifting apparatus adapted for use in an associated vehicle having a floor and one upright wall having an opening therein is provided. The lifting apparatus is operable between a stowed mode and a deployed mode. The lifting apparatus comprises a platform having a generally planar loading surface and adapted for movement between a folded position and an open position, elevator means for selectively moving the platform between an upper level and a lower level, first pivot means being operable to pivot the elevator means and the platform while the platform is in the folded position from an interior side of the opening to an exterior side of the opening about a first pivot member having a first axis generally normal to the floor, and second pivot means for selectively pivoting the platform between the folded position and the open position about a second pivot member having a second axis perpendicular to the first axis. 
     According to another aspect of the invention, the lifting apparatus further includes means for controlling the pivotal motion of the platform about the second axis. 
     According to another aspect of the invention, the first pivot member comprises a post adapted for mounting to the floor of the vehicle at a position displaced from the opening. 
     According to another aspect of the invention, the elevator means includes a telescoping member operable along an axis parallel to the first axis wherein a lower portion is adapted to telescope within an upper portion, the telescoping member being spaced from the first pivot member. 
     According to another aspect of the invention, the lifting apparatus further includes a first cross member extending between the first pivot member and the first portion of the telescoping member. 
     According to another aspect of the invention, the lifting apparatus further includes first switching means for activating the elevator means wherein the first switching means is located on the elevator means. 
     According to another aspect of the invention, the lifting apparatus further includes second switching means for activating the elevator means wherein the second switching means is selectively moveable with the platform. 
     According to another aspect of the invention, each of the up and down movements of the platform is accomplished through hydraulic means. 
     According to another aspect of the invention, a method for utilizing a lift gate apparatus is provided. The method includes the step of pivoting the elevator means and platform while the platform is in a folded position from the interior side of the opening to the exterior side of the opening about the first pivot member; pivoting the platform from the folded position to the open position about the second pivot member; and, utilizing the elevator means to lower the platform to the lower level. 
     One advantage of the present invention is that semi-tractor trailers can be retrofitted with the lifting apparatus to provide access to the cargo area via a side door. 
     Another advantage of the present invention is that the lifting apparatus can be carried within the vehicle interior to prevent unnecessary exposure to the elements and corrosive road salt. 
     Still other benefits and advantages of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may take physical form in certain parts and arrangement of parts. A preferred embodiment of these parts will be described in detail in the specification and illustrated in the accompanying drawings, which form a part of this disclosure and wherein: 
     FIG. 1 is a perspective view of the side lift gate in an unfolded and lowered position. 
     FIG. 2 is a perspective view showing the lift gate with the platform nearly flush with the floor of an associated vehicle. 
     FIG. 3 is a perspective view showing the platform of the lift gate in a partially folded position. 
     FIG. 4 is a perspective view showing the lifted gate in its completely retracted position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, which are for purposes of illustrating a preferred embodiment of the invention only, and not for purposes of limiting the invention, FIGS. 1-4 show the preferred embodiment of the invention. The present invention is shown mounted in an opening in the side of a vehicle  12 . The lift gate assembly  10  is shown near one end  14  of the vehicle  12 . It is to be understood that lift gate assembly  10  can be mounted anywhere on the side of the vehicle  12 , as well as at the rear. Vehicle  12  is provided with an opening  13  through which objects may be loaded or unloaded. In a preferred embodiment, the lift gate assembly  10  is received within the opening  13  when not in use. 
     As seen in the drawings the lift gate assembly  10  has a platform  16  that may be made out of any material chosen with sound engineering judgement, but preferably it is made out of aluminum for lightweight and corrosion-resistant qualities. Preferably, the upper surface  20  is corrugated or ridged for traction. 
     With reference to FIGS. 1-4, the lift gate assembly  10  also comprises a telescoping column  18  which operates to raise and lower the platform  16 . In the preferred embodiment, platform  16  is mounted to stabilizing column  24  which is itself attached to a lower portion of telescoping column  18 . Objects placed upon the platform  16  are thereby raised and lowered so that they may be loaded onto and unloaded off of the vehicle  12 . The column  18  telescopes in a vertical direction, indicated by arrow A, to lift the platform  16  and objects thereon. In the preferred embodiment, column  18  includes three telescoping members having nesting hexagonal cross-sectional shapes, although other configurations are within the scope of the present invention. The column  18  extends in the opposite vertical direction, indicated by arrow B, to lower the platform  16  so that objects may be unloaded from the vehicle. The column  18  may be caused to telescope in any manner chosen with sound engineering judgement, however it is preferred that hydraulic means are used to cause the column  18  to telescope and thereby raise/lower platform  16 . In the preferred embodiment, the lift gate assembly includes first switching means  19 , located on the lower back side of an upper portion of column  18  as shown in FIG. 4, to activate the telescoping mechanism. The operation of this first switching means  19  will be discussed in further detail below. Also in the preferred embodiment, second switching means  28  are provided on a post  26  (shown in FIG.  1 ). Post  26  is preferably mounted onto stabilizing column  24  and remains in a vertical position throughout operation of the lift gate assembly  10 . This second switching means  28  is alternately utilized to cause column  18  to telescope and thereby raise/lower platform  16 . An operator chooses which switching means  19 ,  28  to use, depending on his position relative to the platform  16 . 
     With reference to FIG. 2, the platform  16  is shown as almost being fully lifted by column  18  in a direction indicated by arrow A. It is to be understood that for ease of loading and unloading cargo that the fully lifted position of the platform  16  will have the top surface  20  of the platform  16  substantially flush with the plane of the inside floor  22  of the vehicle. Thus an object that, for example, rolls on casters may be easily wheeled from the top of the platform  20  onto the plane of the floor of the vehicle  22 . Likewise, to remove an object from the vehicle  12 , it may easily be wheeled or rolled from the floor  22  of the vehicle onto the platform  16 . 
     With reference now to FIG. 3, the platform  16  of the lift gate assembly  10  is shown in a partially folded condition. When folding, the platform  16  preferably rotates in a direction toward column  18 , indicated by arrow C in FIG.  3 . In the preferred embodiment, the platform pivots about a stabilizing column  24 , best seen in FIGS. 1 and 2. While a stabilizing column  24  is used in the preferred embodiment, any member about which the platform  16  may pivot may be used in the invention, provided that it is chosen with sound engineering judgment. For instance, the platform may merely be hinged to the telescoping column  18 . Thus, rather than having the stabilizing column  24 , a hinge may connect the platform  16  to the telescoping column  18 . As with the telescoping column  18 , the rotation of platform  16  in the direction indicated by arrow C may be performed in any manner chosen with sound engineering judgement. In the preferred embodiment, manual force is utilized to rotate the platform  16  about the stabilizing column  24 , both from the folded position to an open position as indicated by arrow F and from the open position to the folded position as indicated by arrow C. However, it is conceivable that the operation of the platform can be effected by other means, such as a hydraulic mechanism. 
     For ease of illustration, shown only in FIG. 1, the preferred embodiment of the current invention also includes a vertically extending post  26 , which may be utilized as a handrail by an operator riding on the platform  16  as will be explained in further detail below. Second switching means  28  are disposed near an upper end of post  26 . 
     Again with reference to FIG. 3 when the platform  16  is in its fully upright, folded position, the lift gate assembly  10  may be stored in the interior of vehicle  12  by pivoting about the member  30 . In the preferred embodiment, pivotal movement of the telescoping column  18 /platform  16  combination about member  30  is accomplished by manual force. However, it is anticipated that other means, mechanical, hydraulic, etc., may be employed to accomplish the purposes of the invention. 
     As shown in FIG. 4, once the platform  16  is in its fully upright, folded position and the lift gate assembly  10  is fully closed, the lift gate assembly  10  is recessed within the opening  13  inside of the vehicle  12  or alternately, flush with the side. In the preferred embodiment, the lift gate assembly  10  extends approximately only 10 inches into the interior of the vehicle  12  for compact storage. 
     With reference to FIGS. 1-4, it can be seen that the preferred embodiment of the lift gate assembly  10  includes cross members  32  and  34 . These members  32  and  34  extend between the member  30  and the telescoping column  18 . These members provide support for the lift gate assembly  10 . 
     Applicant notes that in the preferred embodiment, the telescoping column  18 /platform  16  combination pivots toward vehicle  12 , indicated by arrow D about member  30 . However, it is to be understood this may be accomplished in any manner chosen with sound engineering judgement. Accordingly, the member  30 , the cross members  32  and  34  may be hingedly connected to the side of the vehicle  12 . Again, as with the other movements of the lift gate assembly  10 , the movement of the lift gate assembly  10  indicated by arrow D may be accomplished in any manner chosen-with sound engineering judgement. In the preferred embodiment, the lightweight construction of the lift gate assembly  10  allows for manual operation. However, this movement could also be accomplished with hydraulic means. 
     With reference to FIGS. 1-4, a method for operating the lift gate assembly  10  from a fully stored position to an open, deployed position will be illustrated. Initially, access to the interior of the vehicle  12  is made by opening a cargo door, not shown. The telescoping column  18 /platform  16  combination is caused to pivot outwardly about member  30  in a direction indicated by arrow E. In the preferred embodiment, this movement is accomplished manually. Once the combination is fully pivoted about member  30 , the platform  16  may be opened from its folded position by pivotal movement about column  24  in the direction indicated by arrow F. Again, in the preferred embodiment, this operation is accomplished manually. 
     Once the platform  16  has been fully pivoted about the column  24  such that it is parallel to the plane  22  of the floor of the vehicle  12 , the column  18  may be caused to extend in the direction indicated by arrow B. This action is preferably accomplished by hydraulic means activated by first switching means  19 . First switching means  19  are located to be easily accessed by an operator standing on the ground. The platform  16  is ultimately completely lowered to the ground. The operator may mount the platform  16 , and utilize second switching means  28  located on post  26  to raise the platform  16  to the upper position where the top surface  20  is level with the floor of the vehicle  12 . From there, the operator can move cargo onto the platform  16  to unload the vehicle  12 . The second switching means  28  can be utilized again to lower the platform  16 , operator, and cargo to ground level. This process can be repeated as often as necessary to fully unload the vehicle  12 . Post  26  may be utilized as a handrail by the operator for safety considerations. After the cargo is removed, the lowered platform  16  may be raised by activating the first switching means  19 . The platform  16  can be manually folded in the direction of arrow C. Thereafter, the lift gate assembly can be repositioned inside the vehicle interior by pivotal motion about member  30 . It is readily apparent that the vehicle  12  can be loaded with cargo by reversing the actions given above. 
     The preferred embodiment of the present invention exhibits the following characteristics: 
     Bed Height Range . . . Up to 56″ 
     Platform Sizes . . . 28″×39″ 37″×48″ 
     Door Opening Requirements . . . Compatible with doors as small as 39″W×66″H 
     Requirements . . . Compatible with doors as small as 39″W×66″H 
     Capacity 
     Lifting . . . 450 lbs. 
     Lowering . . . 1,000 lbs. 
     The invention has been described with reference to the preferred embodiment. Obviously, modifications and alterations will occur to others upon a reading and understanding of the specification.