Abstract:
Disclosed is a folding chassis of manually driven carrier vehicles, for example, hand trucks, carts, and strollers, capable of moving over uneven, soft or spongy surfaces and surmounting obstacles. The chassis includes a frame having a reference plane and an arm having a first axis and a second axis, said arm being attached rotatable around the first axis to said frame and configured for attaching rotatable, around the second axis, a wheel arrangement having a diameter at least equal to a half of a width of said frame. Said arm is configured to pivot between at least a first and a second positions of said wheel arrangement, wherein, in the first position, said wheel arrangement is generally perpendicular to said reference plane and wherein, in the second position, said wheel arrangement is adjacent and parallel to said reference plane.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part under 35 U.S.C §120 of U.S. Ser. No. 13/575,007, filed Jul. 24, 2012 and published on Nov. 22, 2012 as US20120292889 A1, the entire content of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to manually driven carrier vehicles, such as carts, hand trucks, dollies, and strollers and, more particularly, to a folding chassis therefor capable of traversing obstacles. 
     BACKGROUND OF THE INVENTION 
     Various manually driven carrier vehicles, for example, hand trucks, carts and strollers, are commonly used for moving objects that are otherwise inconvenient for a person to carry due to size and/or weight, or for transporting infants and toddlers. Often, these carts and strollers have foldable chassis for ease of storage and transportation when not in use. These carriers typically have a telescoping or folding handle, a folding chassis, and wheels set into a predetermined position. Such carts and strollers often have limited capability to traverse rough or uneven terrain because the portability requirement in the folded state limits the range of possible wheel diameters, which, in turn, limits suspension responsiveness. This is because the efforts of moving a cart or a stroller at a given coefficient of friction depend inversely on ratios of wheel to axle diameters and the wheel diameter to height of an obstacle. Other carriers, besides having a telescoping or folding handle and a folding chassis, utilize removable wheels of relatively large size as means to improve terrain trafficability, yet reduce overall dimensions in the folded state. However, removing the wheels requires additional time and complicates handling and storage of the carrier, particularly after use on wet or muddy surfaces. 
     Thus, conventional folding carts and strollers, in addition to be able to transport a predetermined load, are designed primarily for convenient handling and portability when folded. However, these known carts and strollers, independently of any trade-offs between the convenience of use and the size in the folded state, are difficult to handle when moving over an irregular terrain, curbs, stairs, and other obstacles. Carrier chassis better capable of dealing with uneven surfaces are inconvenient to store or transport when folded. 
     Therefore, it is desirable to provide a folding carrier chassis capable of moving over a rough terrain, including curbs, stairs, and spongy soil. Additionally, it is desirable to have such carrier chassis be foldable relatively flat to provide for ease of storage and transportation. Further, such chassis should preferably be easily folded without disassembling. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a manually driven carrier vehicle having a foldable chassis configured for moving over uneven, soft or spongy surfaces and surmounting obstacles as well as climbing up and down (i.e. “walking”) over curbs, and stairs, that is easy to handle, convenient to use, and folds flat. Particularly, in its various embodiments and implementations, the invention provides for a decreased pressure applied by the chassis onto an underlying terrain, improved stability, decreased pull/push forces especially for moving over the irregular terrain, and improved portability when folded. As a result, when implemented, the carrier according to various embodiments of the present invention facilitates broader participation in outdoor activities by enabling physically handicapped persons to transport their belongings anywhere easily. 
     Generally, in one aspect, the invention focuses on a folding chassis that includes a frame having a reference plane, an arm having a first axis and a second axis, said arm being attached rotatable to said frame around the first axis and configured for attaching rotatable, around the second axis, a wheel arrangement having a diameter at least equal to a half of a width of said frame, wherein said arm is configured to pivot between at least a first position and a second position of said wheel arrangement, wherein, in the first position, said wheel arrangement is generally perpendicular to said reference plane and wherein, in the second position, said wheel arrangement is adjacent and parallel to said reference plane. 
     In some embodiments, said first axis is positioned at acute angles to said reference plane and to a plane perpendicular to said reference plane. For example, said first axis can be positioned at a first angle to said reference plane in a range from about 15 to 55° and at a second angle to a plane perpendicular to said reference plane in a range from about 30 to 75°. 
     In some embodiments, said wheel arrangement includes at least one wheel. In other embodiments, said wheel arrangement includes a plurality of wheels rotatable around axes parallel to said second axis. For example, said plurality of wheels may include three wheels positioned symmetrically relative to said second axis. Also, in various embodiments, said wheel arrangement in the second position is positioned such that it does not exceed a height of said frame. 
     In some embodiments, the folding chassis includes a platform configured to pivot from been generally perpendicular to said frame to been generally adjacent and parallel to said frame. Said arm and said platform can be configured to pivot simultaneously from the first position of said wheel arrangement and said platform been generally perpendicular to said frame to said wheel arrangement and said platform been generally adjacent and parallel to said reference plane and said frame respectively. Said arm and said platform can be connected by gear segments. 
     In some embodiments, the folding chassis further includes a support pivotally attached to said platform and linked to said frame and said platform, wherein said support configured to pivot between supporting said platform been generally perpendicular to said frame and been generally adjacent and parallel to said platform been generally adjacent and parallel to said frame. For example, said support can be biased to pivot from an intermediate position to one of the end positions. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. 
         FIGS. 1A and 1B  depict respectively a perspective view of an embodiment of a cart chassis in unfolded state according to present invention and magnified partial view of elements of the chassis. 
         FIGS. 2A-2C  depict respectively perspective, back, and side views of the embodiment shown in  FIG. 1A  in a partially folded state. 
         FIGS. 3A-3D  depict respectively perspective, magnified partial, back, and side views of the embodiment shown in  FIG. 1A  in a folded state. 
         FIG. 4  depicts perspective view of another embodiment of the cart chassis in unfolded state according to present invention. 
         FIGS. 5A-5C  depict respectively perspective, back, and side views of the embodiment shown in  FIG. 4  in a folded state. 
         FIGS. 6A and 6B  depict respectively a perspective view of an embodiment of hand-truck chassis in unfolded state according to present invention and magnified partial view of elements of the chassis. 
         FIGS. 7A-7D  depict respectively perspective, magnified partial, back, and side views of the embodiment shown in  FIG. 6  in a partially folded state. 
         FIGS. 8A-8D  depict respectively perspective, magnified partial, back, and side views of the embodiment shown in  FIG. 6  in a folded state. 
         FIG. 9  depicts a perspective view of yet another embodiment of the cart chassis in unfolded state according to present invention. 
         FIGS. 10A-10D  depict respectively perspective, magnified partial, back, and side views of the embodiment shown in  FIG. 9  in a folded state. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, for purposes of explanation and not limitation, representative embodiments disclosing specific details are set forth in order to provide a thorough understanding of the present teachings. However, it will be apparent to one having ordinary skill in the art having had the benefit of the present disclosure that other embodiments according to the present teachings that depart from the specific details disclosed herein remain within the scope of the appended claims. Moreover, descriptions of well-known apparatuses and methods may be omitted so as to not obscure the description of the representative embodiments. Such methods and apparatuses are clearly within the scope of the present teachings. Set forth for better clarity in symmetrical structures, like reference characters may generally refer to like functioning mirrored parts as well as the same parts. 
     Referring to  FIGS. 1A-3D , in one embodiment, a generally symmetrical chassis  110  of a cart  100  includes a bridge  111  that supports a telescoping frame  112  with a handle  113  and has knuckles  114  and  115  at its opposite ends. The knuckles  114  and  115  are mirror images of each other and may be integral parts of the bridge  111  or separate components attached thereto. Each of the knuckles  114  and  115  includes an element  117  for pivoting a platform  118  and an element  119  holding axles  120  that are pivoting axes of respectively arms  121  and  122 . The elements  117  and  119  may be holes or pins as integral parts of each of the knuckles  114  and  115  or attached components. The elements  117  are coaxial and the axles  120  in the elements  119  form acute angles with a reference plane (not shown) of the frame  112 , the symmetry plane, and the platform  118 . As used herein, the reference plane is a plane defined by axes of the elements  117  and general proximity to the frame  112  surface. For example, although the frame  112  is shown as a flat structure it may be not so, in which case the reference plane would be a design feature defining dimensions of the cart  100  in the folded state. For a flat frame, the reference plane may be parallel to the frame surface. The angle to the platform  118  as shown in  FIGS. 1A and 1B  may be in a range from about 30 to about 75°, preferably about 60°, and the angle to the reference plane of the frame  112  may be in a range about from 15 to 55°, preferably about 35°. 
     With continued reference to  FIGS. 1A-3D , gear segments  123  attached to the platform  118  coaxially with the elements  117 . A support  124  may be hinged at a distal end of the platform  118 . Links  125  may connect the support  124  with levers  126  attached pivotally to the platform  118  and connected to the bridge  111  by links  127 . The links  125  and  127  are connected to the levers  126  pivotally as well. In the unfolded state of the chassis  110 , three pivot axes of the levers  126  and the links  127  are aligned in a straight line that prevents the platform  118  from folding. Springs  128  may be placed between the bridge  111  and the links  127  in such manner that the platform  118  and the support  124  through the links  127  and the levers  126  would be biased from an intermediate position to one of either folded or unfolded positions. 
     The arms  121  and  122  are mirror images of each other and each may comprise hinge elements, for example holes, defining an axis of pivoting around the axle  120 , a gear segment  129  meshed with the corresponding gear segment  123 , an element  130  for attaching a wheel arrangement  135  and a catch  131  for engaging the platform  118  in the unfolded position. The element  130 , as an axis of rotation, may be a stationary or rotational axle, a flange or, as shown in this embodiment, a boss with a hole and a latch  132  for a quick disconnect of an axle  133  inserted rotatable through side plates  134 . Multiple wheels  136  may be arranged rotatable between the side plates  134 , constituting a wheel arrangement  135  having a diameter. As used herein, the diameter of the wheel arrangement  135  is understood to mean a diameter of the smallest circle circumscribing the outer reach of the wheels in the wheel arrangement when rotated about the axle  133 . Methods and means of fixing positions of one part relative to another well known in the art so, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function described above. 
     In order to fold the chassis  110 , the support  124  is pushed toward the bridge  111  that, through the links  125 , rotates the levers  126  bringing the common pivot of the levers  126  and the links  127  out of alignment and rotates the platform  118  toward the bridge  111 . Rotation of the platform  118  causes rotation of the arms  121  and  122  toward the bridge  111  through gear segments  123  and  129 . In the folded state, the arms  121  and  122  are generally aligned with the bridge  111  with the wheel arrangements  135  positioned side by side and adjacent and parallel to one side of the bridge  111  while the support  124  is generally adjacent and parallel with the platform  118 , which is generally adjacent and parallel to another side of the bridge  111 . It should be noted that the elements  130  with the wheel arrangements  135  relative to the knuckles  114  and  115  may be positioned higher in the folded state than in unfolded. 
     Referring to  FIGS. 4-50 , in another embodiment, the cart  200  differs from the cart  100  described above in that respect that each of wheel arrangements  201  may consist a single wheel placed on the axle  133  and an optional support extender  202  may be added to the support  124  in order to level the platform  118 . 
     Referring to  FIGS. 6A-8D , in yet another embodiment of the present invention, a generally symmetrical chassis  310  of a hand truck  300  comprise a bridge  311  that supports a telescoping frame  312  with a handle  313  and has knuckles  314  and  315  at its opposite ends. The knuckles  314  and  315  are mirror images of each other and may be integral parts of the bridge  311  or attached components. Each of the knuckles  314  and  315  comprise an element  317  for pivoting a platform  318 , a rotatable gear segment  323 , and an element  319  holding axles  320  that are pivoting axes of respectively arms  321  and  322 . The elements  317  and  319  may be holes or pins as integral parts of each of the knuckles  314  and  315  or attached components. The elements  317  are coaxial while the axes  320  in the elements  319  form acute angles with a reference plane (not shown) of the frame  312 , the symmetry plane, and the platform  318 . As used herein, the reference plane is a plane defined by axes of the elements  317  and general proximity to the frame  312  surface. 
     The angles to the platform  318  as shown in  FIGS. 7A and 8B  may be in a range from about 30 to about 75°, preferably about 60°, and the angle to the reference plane of the frame  312  may be in a range about from 15 to 55°, preferably about 35°. Positions of the knuckles  314  and  315  relative to the bridge  311  are mirror images of respective positions of the knuckles  114  and  115  relative to the bridge  111  in the previous embodiments. 
     The platform  318  includes rockers  324  with cam followers  325  positioned symmetrically and configured to engage slotted levers  328  attached to the gear segments  323 . The rockers  324  are attached to extensions  326  with stoppers  327 , which may interact with the knuckles  314  and  315  and the arms  321  and  322  respectively. 
     The arms  321  and  322  are mirror images of each other and each may include hinge elements, for example holes, defining an axis of pivoting around the axle  320 , a gear segment  329  meshed with the corresponding gear segment  323 , an element  330  for attaching a wheel arrangement  335 , and a stopper  331  for engaging the frame  312  in the unfolded position. The element  330 , as an axis of rotation, may be a stationary or rotational axle, a flange or, as shown in this embodiment, a boss with a hole and a latch (not shown) for a quick disconnect of an axle  333  inserted rotatable through side plates  334 . Multiple wheels  336  may be placed rotatable between the side plates  334 . A diameter of the wheel arrangement  335  is understood to mean a diameter of the smallest circle circumscribing the outer reach of the wheels in the wheel arrangement when rotated about the axle  333 . Methods and means of fixing positions of one part relative to another well known in the art so, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function described above. 
     In the unfolded position, the elements  317  may stop extensions  326  that limits pivoting of the platform  318  to being generally perpendicular to the frame  312 , and, with the elements  330  generally coaxial, the arms  321  and  322  are set between the stoppers  327  of the platform  318  from one side and the frame  312  from another. In order to fold the chassis  310 , the platform  318  is rotated toward the frame  312 . Rotation of the platform  318  causes rotation of the arms  321  and  322  toward the bridge  311  through the cam followers  325 , the levers  328  and the gear segments  323  and  329 . In the folded state, the arms  321  and  322  are generally aligned with the bridge  311  with the wheel arrangements  335  positioned side by side and adjacent and parallel to one side of the bridge  311  while the platform  318  is generally adjacent and parallel to another side of the bridge  311 . It should be noted that the elements  330  with the wheel arrangements  335  positioned relative to the knuckles  314  and  315  lower in the folded state than in unfolded. 
     Referring to  FIGS. 9-10D , in yet another embodiment of the present invention, a generally symmetrical chassis  410  of a cart  400  includes a frame  412  with a handle  413  and has knuckles  414  and  415  at its opposite ends. The knuckles  414  and  415  are mirror images of each other and may be integral parts of the frame  412  or attached components. Each of the knuckles  414  and  415  includes an element  417  for pivoting a platform  418  and an element  419  holding axles  420  that are pivoting axes of respectively arms  421  and  422 . The elements  417  and  419  may be holes or pins as integral parts of each of the knuckles  414  and  415  or attached components. The elements  417  are coaxial and the axles  420  in the elements  419  form acute angles with a reference plane (not shown) of the frame  412 , the symmetry plane, and the platform  418 . As explained previously with reference to  FIGS. 1A-3C , as used herein, the reference plane is a plane defined by axes of the elements  417  and general proximity to the frame  412  surface. The angles to the platform  418  as shown in  FIGS. 10A-10D  may be in a range from about 30 to about 75°, preferably about 60°, and the angle to the reference plane of the frame  412  may be in a range about from 15 to 55°, preferably about 35°. 
     Gear segments  423  attached to the platform  418  coaxially with the elements  417 . A support  424  may be attached pivotally to the platform  418  and to links  425  that as well attached pivotally to the frame  412 . In the unfolded state of the chassis  410 , three pivot axes of the support  424  and the links  425  are aligned in a straight line that prevents the platform  418  from folding. The platform  418  may be biased from an intermediate position to one of either folded or unfolded positions through the support  424  and/or the links  425 . 
     Links  426  attached pivotally to the frame  412  and the handle  413  define positioning of the handle  413  while a latch  427  may lock the handle  413  in unfolded state. 
     The arms  421  and  422  are mirror images of each other and each may comprise hinge elements, for example holes, defining an axis of pivoting around the axle  420 , a gear segment  429  meshed with corresponding gear segment  423 , an element  430  for attaching a wheel arrangement  435 , and a catch  431  for engaging the platform  418  in the unfolded position. The element  430 , as an axis of rotation, may be a stationary or rotational axle, a flange or, as shown in this embodiment, a boss with a hole and a latch (not shown) for a quick disconnect of an axle  433  inserted rotatable through side plates  434 . Multiple wheels  436  may be arranged rotatable between the side plates  434 , constituting a wheel arrangement  435  having a diameter. As used herein, the diameter of the wheel arrangement  435  is understood to mean a diameter of the smallest circle circumscribing the outer reach of the wheels in the wheel arrangement when rotated about the axle  433 . Methods and means of fixing positions of one part relative to another well known in the art so, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function described above. 
     In order to fold the chassis  410 , the support  424  is pushed toward the frame  412 , which rotates the link  425  bringing the pivot axes of the support  424  and the links  425  out of alignment, and rotates the platform  418  toward the frame  412 . Rotation of the platform  118  causes rotation of the arms  421  and  422  toward the frame  412  through gear segments  423  and  429 . In the folded state, the arms  421  and  422  are generally aligned with the frame  412  with the wheel hubs  435  positioned side by side and adjacent and parallel to one side of the frame  412  while the support  424  may be generally adjacent to the platform  118 , which may be generally adjacent and parallel to another side of the frame  412 . It should be noted that, relative to the knuckles  414  and  415 , the elements  430  with the wheel hubs  435  may be positioned higher in the folded state than in unfolded. Following unlatching the latch  427 , the handle  413  may be rotated about 180° with the links  426  rotated about 270° to overlap the platform  418 . 
     Consequently, in its various embodiments, the present invention provides the versatile folding chassis for easily moving over all kinds of terrain, traversing curbs, as well as ascending or descending stairs. Furthermore, the invention provides that such chassis folds relatively flat for better handling and storage in the folded state. 
     While several inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. For example, a removable track may be fitted over the wheels  151  of each of the hubs  150  for moving over a sandy or spongy terrain. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto; inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure. 
     Accordingly, as indicated above, the foregoing embodiments of the invention are examples and can be varied in many ways. Such present or future variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be apparent to one skilled in the art are intended to be included within the scope of the following claims. 
     All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.