Patent Publication Number: US-2019176707-A1

Title: Foldable ladder structure for automobile cargo bed

Description:
(a) TECHNICAL FIELD OF THE INVENTION 
     The present invention generally relates to a foldable ladder structure, and more particularly to a foldable ladder design for mounting to an automobile cargo bed to allow a user to enter or exit the cargo bed without occupying additional space. 
     (b) DESCRIPTION OF THE PRIOR ART 
     Automobiles are a convenient transportation. For some passenger/cargo dual-purpose automobile, such as a pickup truck, off-road performance is excellent so that it can be used as a passenger car for carrying passengers and it also has a cargo bed provided on the rear side to carry cargos, making the use thereof extremely wide and convenient. However, the structural arrangement of the body of such an automobile often present an issue that the height of the cargo bed is considered relatively high for most persons. In addition, the cargo bed also has a depth that is relatively deep and long as compared to the regular sedans. Thus, it is sometimes inconvenient in loading and unloading cargo into and from the cargo bed. Particularly, climbing up and down the cargo bed in loading and unloading cargos appears to be a challenge to physical strength and may causes physical tiredness and exhaustion of the user. One way to handle such a problem is to provide a stepping device having a proper height on the ground to ease climbing up and down the cargo bed. The stepping device, however, is a movable device and is sometimes poor in respect of stability and may get undesired movement as sliding on the ground, leading to fall of the user. In addition, such a stepping device, once placed in the cargo bed for being carried with the automobile, would occupy a certain amount of space of the cargo bed, making it imperfect in use and operation. 
     In view of this, the present invention aims to provide a foldable ladder structure that is directly mountable to a cargo bed of an automobile. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a foldable ladder structure for an automobile cargo bed, which can be directly mounted to and collapsed to store by a sidewall of the cargo bed so as not to occupy cargo storage space of the cargo bed and also to allows efficient expansion upon use to be securely installed between the cargo bed and the ground to allow a user to step thereon for climbing and crawling in order to provide convenience and safety for the user to enter and exit the cargo bed. 
     To achieve the above objective, the present invention provides a foldable ladder for an automobile cargo bed, generally comprising a mounting base, a pivot axle, a frame, extension/retraction bars, and a ladder assembly, wherein the mounting base is mounted to a stop pillar of a gate board at a tail of a cargo bed the sideboard and is pivotally coupled, with a bottom thereof, to a pivot axle by means of a first pivot joint unit. The pivot axle is pivotally coupled to a pivot joint end of the frame to form a second pivot joint unit. The extension/retraction bars are respectively coupled to two side portions of the frame and are extendable outward from an operation end. Ends of the extension/retraction bars are pivotally coupled to a ladder assembly by means of a third pivot joint unit. The ladder assembly comprises at least one rung for stepping thereon. 
     As such, the foldable ladder of the present invention can be collapsed, by means of the pivot joint units, to normally positioned against a sideboard between the stop pillar of the gate board and a wheel arch so as not to occupy a space of the cargo bed and can be efficiently turned and extended to expand and position at the rear side of the cargo bed to make the ladder assembly stably support between the cargo bed and the ground for use. 
     The foregoing objectives and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts. 
     Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of the present invention. 
         FIG. 2  is a perspective view of the present invention in an expanded condition. 
         FIG. 3  is a perspective view of the present invention in a folded condition. 
         FIG. 4  is a schematic view illustrating a state of use of the present invention as being mounted to a cargo bed in a folded condition. 
         FIG. 5  is a schematic view illustrating an expanding operation of the present invention. 
         FIG. 6  is a schematic view illustrating another expanding operation of the present invention. 
         FIG. 7  is a schematic view illustrating a state of use of the present invention as being mounted to the cargo bed in an expanded condition. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following descriptions are exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims. 
     Referring to  FIGS. 1-4 , the present invention provides a structure of a foldable ladder  1 , which generally comprises a mounting base  10 , a pivot axle  20 , a frame  30 , extension/retraction bars  40 , and a ladder assembly  50 . The mounting base  10  is pivotally coupled, by means of a first pivot joint unit  1   a , to the pivot axle  20 , and the pivot axle  20  is pivotally coupled to a pivot joint end of the frame  30  to form a second pivot joint unit  1   b . The frame  30  has two side portions that are respectively coupled to extension/retraction bars  40  that are extendable outward from an operation end thereof. The extension/retraction bars have extension ends that are pivotally coupled, by means of a third pivot joint unit  1   c , to the ladder assembly  50 . 
     The mounting base  10  is made in a plate-like structure that is provided with a plurality of fixing holes  11  formed therein for receiving bolts for fixing to and positioning on a stop pillar  63  that is located at one side of a gate board  62  on a tail part of sideboards  61  of an automobile cargo bed  60 . In the preferred embodiment shown in the drawings, the mounting base  10  further comprises an L-shaped board  12  arranged at one side of the plate thereof and bent inward for being extended in a recessed area behind the stop pillar  63 . The first pivot joint unit  1   a  is arranged at a bottom of the L-shaped board  12  so that the foldable ladder  1  of the present invention can be installed in a manner of being completely positioned against the sideboard  61  (as shown in  FIG. 4 ). Further, to embody the first pivot joint unit  1   a , the L-shaped board  12  so extended is provided with a pivot seat  13  thereon and a pivot joint end of the pivot axle  20  is connected with a pivot sleeve  21  in a radial direction such that a pin  14  is receivable through the pivot seat  13  and the pivot sleeve  21  for pivotal coupling, allowing the pivot axle  20  to rotate in a direction toward the mounting base  10  to be positioned thereon. 
     The frame  30  is provided, on the pivot joint side thereof, with a tube  31  that is directly fit over and coupled to the pivot axle  20  to be fixed together by means of a fastener element  22  to form the second pivot joint unit  1   b , so that the frame  30  is allowed to rotate, by means of the end of the pivot axle  20  pivotally coupled to the pivot seat  13 , in directions toward front and rear sides of a body of the automobile. Further, the extension/retraction bars  40  are directly fit, at the operation side of the frame  30 , into interiors of two side bar members  32  of the frame and are provided with a connection bar  41  coupled between the extension ends thereof. The side bar members  32  have outer side surfaces in each of which a recessed groove  42  is formed with a stop plate  43  mounted to a bottom end of the recessed groove  42 . A side wall each of the two side bar members  32  of the frame  30  is provided, at an open end thereof, with a stop pin  33  that corresponds to the recessed groove  42  and projects inward to constrain and thus prevent the extension/retraction bars  40  from detaching from the frame  30  upon being pulled outward. 
     The ladder assembly  50  comprises at least one rung  51  provided between two side bars and is pivotally coupled to the extension/retraction bars  40  of the frame  30  by means of the third pivot joint unit  1   c  so that the ladder assembly  50  can be positioned flat on the frame  30  through rotation of the third pivot joint unit  1   c . To embody the third pivot joint unit  1   c , a coupling seat  44  is mounted to an external end of each of the extension/retraction bars  40  of the frame  30 . The coupling seat  44  has an end face that forms a slope  45 . An end of the slope  45  is provided with a protrusion plate  47  that comprises a pivot joint hole  46 . The two side bars of the ladder assembly  50  are each coupled, at a pivot joint end thereof, with clamp blocks  52  that correspond to the protrusion plate  47  and the clamp blocks  52  are provided with an axle hole  53  penetrating through lateral sides thereof and corresponding to the pivot joint hole  46  for pivot coupling with a pivot joint element  54  to form the third pivot joint unit  1   c.    
     Referring to  FIGS. 2-4 , the foldable ladder  1  of the present invention uses the mounting base  10  to mount to the stop pillar  63  at one side of the gate board  62  of the automobile cargo bed  60 . In a normal, non-use condition, the ladder assembly  50  is collapsed and laid flat on the frame  30  by means of the third pivot joint unit  1   c , and meanwhile, the extension/retraction bars  40  are retracted back into the interiors of the side bar members  32  of the frame  30 , and then, the frame  30 , together with the ladder assembly  50 , is rotated in a direction toward the front side of the automobile body through 180 degree rotation of the second pivot joint unit  1   b  and finally, rotated through the first pivot joint unit  1   a  to be erected vertically for positioning against the sideboard  61  for storage between the stop pillar  63  of the gate board  62  and a wheel arch  64 . As such, in a non-used condition, the foldable ladder  1  of the present invention occupies hardly any useful operation space the cargo bed  60  and does not interference with the operation performance of the cargo bed  60 . 
     Referring to  FIGS. 4-7 , in an attempt to use the foldable ladder  1  of the present invention, it only needs to make a downward rotation through the first pivot joint unit  1   a  to be horizontally positioned and then a rotation of 180 degrees is made toward the rear side of the automobile body by means of the second pivot joint unit  1   b  and at the same time, the extension/retraction bars  40  of the frame  30  are pulled, together with the ladder assembly  50 , in a rearward direction for extension (as shown in  FIG. 5 ), and then the ladder assembly  50  is turned over by means of the third pivot joint unit  1   c  for expansion (as shown in  FIG. 6 ) to achieve downward positioning for being supported between the gate board  62  at the tail side of the cargo bed  60  and the ground to allow a user to step on and climb or crawl in getting on or off the cargo bed  60  (as shown in  FIG. 7 ). Further, since the third pivot joint unit  1   c  of the foldable ladder  1  of the present invention is provided with a structural arrangement that includes a slope  45  at an end surface of the coupling seat  44  of each of the extension/retraction bars  40 , when the ladder assembly  50  is expanded and set up, sides of ends of the side bars of the ladder assembly  50  are in contact with and restrained by the slopes  45  to demonstrate a proper angle for being set between the gate board  62  and the ground. As such, it is possible to prevent the ladder assembly  50  from hitting the gate board  62  and thus causing damage of the gate board  62  resulting from excessive turning during turning or caused by climbing or crawling, and also allowing the ladder assembly  50  to be set up in an inclined manner, allowing for convenient and stable use by a user for stepping on and climbing. 
     It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. 
     While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the claims of the present invention.