Abstract:
The arched multi-segmented ramp assembly of the present invention has the advantageous qualities of being portable, lightweight, easily deployable and storable. Identical step links have keystone-shaped sides that abut adjacent members and are joined one to the other by knuckle-like hinges, both of which structural features impart to the unrolled assembly a gently arcuate contour, thereby enhancing the ramp&#39;s strength to weight characteristics compared to ramps of the prior art. The hinge connections further permit the ramp to be rolled up for easy transport and storage. Because of its modular design, the arched ramp may be assembled using varying numbers of component step-links, thus providing a user with the flexibility to form a ramp assembly with lengths suitable for different particular applications.

Description:
FIELD OF THE INVENTION 
   The present invention is directed to load bearing structures which permit loading and access to be accomplished in a simple and effective manner. Still further, the subject invention pertains to load bearing structures which may be used to load weights from a base surface to a surface which is vertically displaced from the base surface. Still further, this invention is directed to a load bearing structure which may be interfaced with a ground surface on one end and a vehicle or a platform on the other end to allow loading of weights from the ground surface to the elevated surface. More in particular, this invention is directed to a ramp type structure which on one end may interface with the ground surface and on the other end, interface and be contiguous with a vertically displaced surface, as of a platform or of a vehicle for loading weighted material from the ground surface into the vehicle. More in particular, this invention is directed to a ramp structure which is portable and may be deployed upon the desire to load a weight onto a vehicle or platform. Further, this invention relates to a deployable arched ramp type structure which is formed in multi-segments for easy deployment for loading of a pet or other type animal from a ground surface to a vertically displaced surface. 
   Additionally, the subject invention pertains to a multi-segmented deployable arched ramp structure which may be rolled or folded into a compact volume when not in use. Still further, the subject invention is directed to a portable ramp structure which attains an arched or arcuate contour between a base surface and a vehicle surface to aid in its load bearing properties. Additionally, the subject invention directs itself to a multi-segmented deployable arched ramp which is formed of interdigitated segmental fingers or lug elements which are at least partially rotatable each with respect to the other to permit the arched ramp structure to be rolled into a compact volume. 
   Still further, the subject invention directs itself to a deployable arched ramp structure which permits ease in the loading or entry of a pet or other animal from a base surface which is vertically displaced from the vehicle surface or platform onto which the pet or other animal is being loaded. Additionally, the subject invention system is directed to a deployable arched ramp structure which is formed of lightweight plastic material members for ease of transportation of the arched ramp structure. 
   BACKGROUND OF THE INVENTION 
   Loading and unloading of domestic animals from vehicles is a somewhat difficult project for both the animal and the person who is loading the animal. A number of factors contribute to the difficulty of loading the animal into a vehicle or onto an elevated surface, which includes the weight of the animal; the elevation of the entryway; the age and mobility of the animal; the age and mobility of the animal owner; and the terrain from which the loading/unloading is taking place. Additionally, once loaded onto the vehicle or platform, there exists a need for compacting of the volume of the loading structure. The compaction of the volume allows for more space of the animal in the loaded vehicle and allows the loading structure to be transported to another site where the animal is to be removed from the vehicle. 
   There exists a need for a compact, lightweight, and structurally capable loading structure to assist in the loading and unloading of animals from vehicles or other such surfaces. 
   PRIOR ART 
   Ramps for permitting the loading and unloading of animals from mutually vertically displaced surfaces is known in the art. Some known ramps are currently available to assist an animal owner with loading and unloading tasks. However, a number of these prior art systems have limitations and still prove difficult for the animal owner in the loading and unloading process. 
   Some prior art loading ramps are rigid one or two-piece units fabricated from board planking or aluminum extrusions. In some cases, plastic fabricated loading ramps formed from plastic compositions with steel reinforcing rods for structural support have been used. 
   Single piece units are generally long, heavy and difficult to store when not in use and cannot be conformed to a low volume compact package. 
   Two-piece units may fold and are easier to store than single piece ramp structures; however, they still are heavy and cumbersome in their use. 
   The best prior art known to the Applicant includes U.S. Pat. No. 6,463,613; No. 6,430,769; No. 6,398,479; No. 6,322,310; No. 6,269,508; No. 6,116,839; No. 6,119,634; No. 5,870,788; No. 5,347,673; No. 5,062,174; No. 4,815,155; and, #D440,717. 
   U.S. Pat. No. 6,463,613 is directed to a portable and collapsible ramp system. However, the load bearing portion of the ramp is formed by a multiplicity of slats which are pivotally connected to one another by several flexible straps. Rigid support of the central ramp portion of this prior art system is provided by braces. However, this prior art portable ramp is severely limited in its load bearing capabilities and provides for a substantially planar extension of the portable ramp. 
   U.S. Pat. No. 6,430,769 is directed to a wheelchair ramp which includes a pair of ramp sections joined by a keyway joint connecting the ramp sections. This prior art system is representative of a rigid ramp structure which may be folded upon itself to bring some compactness to the overall volume, however, does not permit a rolling up of the ramp structure to minimize the storage volume. Additionally, this ramp is further representative of a planar extending ramp structure which does not utilize the arcuate or arched concept to increase the load bearing capabilities as provided in the subject system. 
   U.S. Pat. No. 6,398,479 is directed to a still further prior art lifting platform which is used generally for transporting a wheelchair passenger into and out of the rear door of a vehicle. This type of prior art ramp or platform is another example of a folding type platform which extends in a planar direction during use and does not include any arched or arcuate extension to aid in absorbing the load imparted thereto. 
   Thus, there still exists a need for a ramp type structure which is lightweight, is structurally capable of accepting the loads imparted thereon, which is lightweight for ease of deployment and has the ability of being rotatably compacted to allow storage in a small volume. 
   SUMMARY OF THE INVENTION 
   The need for a portable, lightweight, easily deployable and storable ramp is met by the arched multi-segmented structural walkway ramp provided in the present invention. 
   The arched ramp structure of the present system includes a concatenation of substantially identical structural sections or step links. Each of the links has a mechanism for hinged connection to adjacent sections. Structural stop features on the hinge elements are provided which impinge upon the adjacent sections when deployed. The assembled array of step links has the capability of pivoting and rolling up freely in a unitary direction, however, the ramp assembly  10  becomes a rigid arched bridge structure when unrolled and deployed into its operative position. 
   The load-carrying features of the arched structural walkway include a pair of opposing keystone-shaped side wall members formed on each step link that are designed specifically to cam up onto the identical features on adjacent step links, thereby providing load-bearing support. Additionally, each of the longer transverse sides of each step link has formed thereon a plurality of hinged knuckle members. 
   When fully deployed, the assembly is contoured into an arched form with concomitant improvement in strength-to-weight ratio compared to other foldable and rollable ramps. Each step link of the assembled structure has a shaped walking surface that may be textured for improved traction by the user such as the animal being loaded into the vehicle. 
   The ramp assembly is designed as an intermediate structure between a ramp and a ladder with raised cleat portions on the upper surfaces of the link steps adapted to provide an animal with an improved frictional surface to push against while walking up or climbing the ramp structure and alternatively, to support the animal&#39;s weight when the animal is descending from the vehicle. Each of the structural step links for the ramp assembly is envisioned in one embodiment as an injection molded plastic component for ease of manufacture and for minimizing the manufacturing costs. Alternative materials may be used to construct such an assembly with the important factor being that the materials used must have sufficient structural integrity to support the loads applied thereto. 
   The step links are connected each to the other along their respective extended or long transverse sides by interdigitation of the knuckle members within the hinge elements. The connection between adjacent step links is further stabilized by the use of an extruded hinge tube such as a plastic tubing—substantially flexible or rigid—that is passed through the channel formed by the openings of the substantially cylindrical knuckle members or knuckles. The open ends of a hollow extruded hinge tube are covered with an injection molded end cap that is seated in the openings of the channel formed by the co-linear knuckles on each transverse side of an assembly. 
   The first and last step link of the assembly include the knuckle-containing sides covered with a bumper or synonymously a foot portion, formed from an extruded elastomer and which may be secured adhesively to the ends of the assembly. 
   When deployed, the assembly forms an arched structure with a gentle convex arcuate profile or contour which imparts to the assembly a relatively increased weight-bearing capability while maintaining the weight of the structure in a minimized condition. This relatively increased weight-bearing of the assembly may be attributable at least in part to the keystone-like shape of each of the compression members. Rather than sagging in the middle as weight is applied to a flat ramp typical of the prior art, the ramp assembly  10  disperses the force of the applied weight by transferring that force through the compression members  25  along adjacent step links  20  and maintaining an arcuate contour  71 . 
   The modular component design of the present invention permits freedom to manufacture assemblies to suit particular applications. For example, an assembly of fifteen step links can provide ingress/egress from most automobiles. Alternatively, in another preferred embodiment, an assembly of nineteen step links may be used for ingress/egress from a larger SUV-type vehicle. 
   Assemblies of different lengths defining different numbers of step links may be manufactured or fabricated at the factory and may be sold as a given length for a given end use. 
   In another preferred embodiment, an extension kit permits an end user with a first number of sections assembly to add a further set of sections assembly and extend the concatenation of step links. 
   In another preferred embodiment, the assembly may be formed from a stronger material such as die cast aluminum alloy. In a still further alternative embodiment, such assembly may be used in pairs to form a stronger roll-up ramp to be used for loading and unloading of all-terrain vehicles, garden tractors, wheelchairs, and the like onto and off of a vehicle such as a pickup truck. 
   As an example, the width of each link and therefore the width of the assembly may be in the range of approximately 6—18 inches. The preferred embodiment of this invention supports a weight load of approximately 200 pounds, at least. Individual arched ramp assemblies may be designed to support various loads that exceed the 200 pound limit, insofar as the weight carrying capacity of the ramp assembly is a function of the basic materials used in its manufacture. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a perspective view of the deployed multi-segmented arched ramp showing an animal being loaded onto a pickup truck; 
       FIG. 1B  is an elevational view of the multi-segmented deployed arched ramp of the subject invention; 
       FIG. 2A  is a perspective view of three joined step links of the subject deployable arched ramp including a blowout of a hinge pin; 
       FIG. 2B  is a perspective view of the arched ramp partially in a rotated position; 
       FIG. 3  is a bottom view of three joined step links of the deployable arched ramp of the subject invention; 
       FIG. 4  is a cross-sectional elevational view of a step link taken along the cross-section Line  4 — 4  of  FIG. 2A ; 
       FIG. 5  is a perspective view, partially cut-away, of an end step link and a bumper member of the subject invention system; 
       FIG. 6  is an elevational view of the multi-segmented deployable arched ramp of the subject invention in a rolled or compacted condition; and, 
       FIG. 7  is a perspective view of two multi-segmented deployable arched ramps in deployment from a base surface to the bed of a vehicle. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to  FIG. 1A , there is shown multi-segmented deployable arched ramp assembly  10  for aiding in the loading of animal  17  from a base surface  11  which may be the ground to the bed base surface  13  of vehicle  15 . Animal  17  may be loaded in directly into the bed of vehicle  15  or guided easily into cage  19  mounted on the bed base surface  13  of vehicle  15 . 
   As can be seen in  FIGS. 1A and 1B , multi-segmented deployable arched ramp assembly  10  when in the fully deployed contour or condition is arcuately directed or assumes a gently arched profile as depicted by arcuate directional arrow  71 . As will be seen in following paragraphs, the deployment of deployable arched ramp  10  permitting the arcuate profile permits the load from one step link member  20  to be absorbed somewhat and imparted to adjacent step link members  20  to increase the load bearing capability of the overall assembly  10 . The arched structure of the unfolded or deployed assembly  10  shown in  FIGS. 1A and 1B  provides for an increased weight-bearing capability to ramp assembly  10  improving the strength-to-weight ratio of the present invention compared to prior art ramp assemblies. 
   It is to be understood that two important objectives of the present invention are to provide both a weight bearing ramp suitable for loading pets and/or other such animals onto a vehicle and further has the objective of being foldable, portable, and providing material qualities which allow for a lightweight overall assembly  10 . The arched or arcuate form of the ramp assembly  10  in its deployed state may be further appreciated by reference to the side-views of  FIGS. 1A ,  1 B, and  7 , and is achieved by limiting the extent to which each component step link member  20  can be rotated with respect to its adjacent step link members  20 ′. The particular elements of the present invention that constrain the limitation of rotation of one step link member relative to its adjacent step link members will be discussed in greater detail below. 
   Further illustrated in  FIGS. 1A and 1B  is the segmental nature of the ramp assembly  10 , which is comprised of a concatenation of step link members  20  that are hingedly joined along their adjacent longitudinal sides. 
   The nature of each component step link  20  may be appreciated by reference to  FIGS. 2A ,  2 B, and  3 , in which three step links are shown joined together. All component step link members  20  are substantially identical in the preferred embodiment. A step link member  20  functions as a stepping surface, which in the preferred embodiment has a roughly rectangular shape, with one step link member  20  connected to adjacent step link members  20 ′ along the longer side of the rectangle. Each step link member  20  is comprised of an upper surface  23  and a lower surface  24 , which in the preferred embodiment are two opposite sides of a unitary piece. The step link member  20  of the preferred embodiment has formed on its upper surface  23  a cleat  27  for improving the traction of the surface on which a pet  17  would be walking. The raised cleat  27  on the arcuate deployed assembly  10  accomplishes this improved traction by functioning to some extent as a ladder step whereon an animal  17  may place its paw on the raised cleat  27  and push off it so as to advance successively from one step link member  20  to the next step links. 
   On either side of the step link member  20 , that is, on its opposing transverse sides, compression members  25  are formed that extend upward in a substantially perpendicular orientation relative to the upper surface  23  of the step link member  20 . 
   Each compression member  25  has a roughly horizontal upper side  51  substantially parallel to a lower side  53  that are both connected to the two roughly vertical abutment sides  55 . The length of the upper side  51  is greater than the length of the lower side  53 , thereby imparting a roughly keystone shape to the profile of the compression member  25 , as illustrated in  FIG. 4 . The compression member sides  51 ,  53 ,  55  need not be straight but may be formed with an arcuate contour; in such cases the distance between the vertices where the upper side  51  connects with the vertical abutment sides  55  is greater than the distance between the vertices where the lower side  53  connects with the vertical abutment sides  55 . 
   The compression members  25  connect to opposite transverse sides of the step link member&#39;s  20  upper surface  23  along the compression member&#39;s lower side  53 . In a preferred embodiment of the ramp assembly  10 , the compression members  25  are formed with a plurality of truss elements  57  that connect the upper side  51  and the lower side  53  in an oblique manner, dividing the recess formed by the compression member sides  51 ,  53 ,  55  into roughly triangular shaped spaces. There is also provided in the preferred embodiment an inner wall element  58  that further defines a compression member recess and connects all of the compression member sides  51 ,  53  and  55 . The inner wall element  58  may be omitted or modified in other embodiments of the present subject invention. 
   It may be further appreciated with reference to  FIGS. 2A and 4  that by having the upper side  51  longer than the lower side  53  the abutting of adjacent vertical abutment sides  55  of the step link members  20  in the course of deploying the ramp assembly  10  prevents the step links  20  from assuming a co-planar relationship and imposes thereby the arched or arcuate profile  17 . 
   The hinge elements of each step link member  20  are formed along each of the longitudinal sides of a step link member  20  and comprise a plurality of substantially cylindrical shaped knuckle members  21 . The number of knuckles of the hinge mechanism of ramp assembly  10  may be varied according to a particular embodiment; in the preferred embodiment there are eight knuckles  21  on each articulating longitudinal side of a step link member  20 . This number of knuckles  21  is illustrated in  FIG. 3 ; a hinge mechanism with the four knuckles  21  shown on the other illustrated step link members represents an alternative embodiment and is not in any way meant to constrain or limit the number of knuckles formed on a step link member  20 . 
   The knuckle members  21  are regularly spaced along the longitudinal sides of a step link member  20 , and oriented longitudinally so that their substantially cylindrical central bores  31  are in alignment. As may be further appreciated by reference to the Figures, the different positioning of the knuckles  21  distinguishes one longitudinal side of a step link member  20  from its opposite longitudinal side, whereby the positioning of the regularly spaced knuckle members  21  is adapted so that the knuckle members  21  of one step link member  20  may complementarily interdigitate with the knuckle members  21 ′ of an adjacent step link member  20 ′. When juxtaposed, as seen in  FIG. 2B , the interdigitating knuckle members  21  form a channel  31  that constitutes an axis of rotation for one step link member  20  relative to an adjacent step link member  20 ′. 
   There is formed on each knuckle member  21  a transversely oriented protrusion stop member  22  which is also seen in  FIG. 4 . When a step link member  20  is rotated in an unfolding direction relative to its adjacent step link member  20 ′, the range of excursion is limited by the abutment of protrusion stop member  22  with upper surface  23 ′ of the adjacent step link member  20 ′. The placement of the protrusion stop members  22  is in a location to partly constrain the unfolding rotation of the ramp assembly  10  and results in an arched, non-co-planar contiguous relationship between adjacent step link members  20 ,  20 ′. This non-co-planar relationship between adjacent step links  20  is mildly convex up, and imparts to the unfolded ramp assembly  10  its arcuate profile. In contradistinction to the unfolding condition, a folding rotational movement of adjacent step link members  20  is not constrained by the protrusion stop members  22 , thereby permitting the ramp assembly  10  to be rolled into the portable compact condition illustrated in  FIG. 6 . 
   The transverse channel  31  formed by the co-linear interdigitated knuckle members  21  houses a hinge pin  30 , seen in  FIG. 2A , which maintains the contiguous relation between adjacent step link members  20  during rotational movement. Without the hinge pin  30  holding adjacent step link members  20  in contiguous relation, the step link members  20  would separate upon the folding rotation as described above. In the preferred embodiment, the hinge pin  20  is comprised of a lightweight hollow plastic tube and has seated in each of its open ends an end cap  35 . 
   The lower surface  24  of each step link member is illustrated in  FIG. 3 , showing two step link members  20 ,  20 ′ hingedly joined on the left and a third step link member  20 ″ aligned so as to permit the hinging connection of that third step link member  20 ″ to the middle step link member  20 ′. The interdigitation of the knuckle members  21  is permitted by this alignment and hinge pin  30  is shown in alignment with the channel  31  formed by the co-linear cylindrical knuckle members  21  and further indicated in  FIG. 3  by an interrupted dotted line. 
   In the preferred embodiment illustrated, the lower surface  24  of each step link member  20  has formed thereon a plurality of support ribs  26  that are truss elements which give strength and augmented weight-bearing capability to the step link members  20 . In the preferred embodiment as illustrated in  FIG. 3 , each of the support ribs  26  extends in a substantially longitudinal direction, extending from a longitudinal side contiguous with the knuckle member  21  to its opposite side. Alternating support ribs  26  are seen to be approximately parallel to each other in this preferred embodiment, but other arrangements of the support ribs  26  may be provided in other embodiments, or omitted altogether depending on the materials used and the anticipated function of the ramp assembly  10 . 
   The arched form of the ramp assembly  10  in its open deployed state is accomplished both by the action of the protrusion stop members  22  to constrain rotation of adjacent step link members  20 , as well as by the abutting of the vertical abutment sides  55  of adjacent compression members  25  one to the other. The difference in lengths between the upper side  51  and the lower side  53  of each compression member  25  constrains the opening or, equivalently, the deploying rotation of the step link members  20  by the abutting juxtaposition of a pair of vertical abutment sides  55  of the compression members  25  of one step link member  20  with the adjacent pairs of vertical abutment sides  55 ′ of compression members  25 ′ of step link members  20 ′. It can thus be appreciated that the ramp assembly  10  in its deployed state is constrained to its gently arched form by two important elements of the preferred embodiment, namely, the keystone shape of abutting compression members  25  as well as the positioning of the protrusion stop members  22  formed on the outer surfaces of the knuckle members  21 . 
   The ramp assembly  10  in its deployed condition has one end resting on a base surface  11  and the other end on the vehicle bed surface  13 . Since the assembly  10  in its preferred embodiment is made of a relatively hard plastic, or in other embodiments even harder material, the ends are fitted with elastomeric bumpers  40  that fit onto the step link ends. By fitting the ramp&#39;s ends with these bumpers, it is less likely that use of the ramp assembly  10  may scratch or mar either of the surfaces bridged by the ramp assembly  10 . Furthermore, by making an elastomeric bumper  40  the element in contact with these surfaces, it is much less likely that the ramp assembly  10  can slip out of proper position which would endanger an animal  17  using the ramp  10  as well as possibly damage the vehicle  15  and or floor  11 . 
     FIG. 5  illustrates the location and function of a bumper  40 , a unitary piece formed and adapted to fit in a contiguous protective manner over the row of knuckles  21  formed on an end step link member  20 . In the preferred embodiment, such a bumper  40  is made of a resilient elastomeric material. The upper and lower bumpers provide the contact surfaces at the two ends of each arched ramp assembly  10  where the arched ramp assembly  10  makes contact with the two surfaces that it is bridging. Bumpers  40  in the preferred embodiment are adhesively joined to the end step link members  20 , but other ways of securing the bumpers  40  in a contiguous relationship to the knuckle-bearing longitudinal sides are not precluded for other embodiments. 
   An important objective of the present invention is a ramp that is portable. By making the ramp  10  with rotatable step links, a user may unroll the ramp when desiring to transfer an animal  17  into or out of a vehicle  15 . Once this has been accomplished, the ramp assembly  10  is easily rolled back into the compact condition for ease of transport and efficiency of storage.  FIG. 6  illustrates the rolled-up condition of a ramp assembly  10 , the state in which the ramp assembly  10  is to be stored or carried. In a preferred embodiment, the folded rolled-up ramp assembly  10 , with bumpers  40  and nineteen joined step link members  20 , assumes a roughly cylindrical shape with an outer diameter of approximately 15″. The ramp assembly  10  with fifteen joined step link members  20 , has an approximately 13″ outside diameter when in a rolled-up condition. 
   While the preferred embodiment of the present invention is directed to its use for transferring animals  17  to and from vehicles  15 , the structure may be applied with insubstantial modifications for other tasks requiring greater weight bearing capability, but modified dimensions to suit other intended functions. For example, stronger materials may be used for moving heavier objects or animals, but those stronger materials usually weigh more than plastic; the intended function may not require the same width as the preferred embodiment however, so narrower ramps  10  may be used that serve the purpose and keep the weight at a minimum. 
   The preferred embodiment of the present ramp assembly  10  is formed with a relatively hard plastic, except for the bumpers  40  that are made from an extruded piece of EPDM or similar elastomer. In another possible embodiment the component step link members  20  of the ramp assembly  10  may be formed from a stronger material, such as die cast aluminum alloy, and further formed so as to make the width of each step link member  20  approximately 8″. When used in pairs, such a narrower and stronger ramp assembly is suitable for loading and unloading all-terrain vehicles, garden tractors, or the like, onto and off of a pick-up truck or the like. This alternative embodiment is illustrated in  FIG. 7 . 
   In another preferred embodiment, the present invention encompasses a mounting bracket to permit a user to firmly affix one end of the ramp the end or underside of a table or platform, so as to permit a user to roll the deployed ramp into the compacted condition and to reversibly strap or otherwise secure the rolled up ramp under the table or platform in a manner that makes it convenient and easy to re-deploy the arched ramp assembly as needed. 
   An alternative embodiment of the present invention is formed with means for reversibly joining two or more such arched ramp structures side-by-side so as to permit a user to assemble an arched ramp structure with a width equal to the number of component arched ramp structures times the width of an individual arched ramp structure. Such means may encompass a clip, a Velcro™-type system, or other reversible joining means. 
   While the present invention has been shown and described in terms of a preferred embodiment thereof, it will be understood that this invention is not limited to this particular embodiment and that many changes and modifications can be made without departing from the true spirit and scope of the invention as defined in the appended claims. In addition, as used herein and in the claims, such words as “upper”, “lower”, “top”, “bottom”, and “side”, and the like are used in conjunction with the Drawings for the purposes of clarity, and it will be appreciated that they do not limit the device to a particular orientation.