Abstract:
Disclosed is a folding chassis of manually driven carrier vehicles, for example, hand trucks, carts, and strollers, capable of moving over uneven or spongy surfaces and surmounting obstacles. The chassis includes a frame having a first plane, an arm with an axle, and a hub having a plurality of wheels. The arm is rotatably attached to the frame with the hub rotatably disposed onto the axle and each of the plurality of wheels is rotatably attached to said hub around an axis parallel to said axle. The arm is configured to pivot between at least positions of the hub been generally perpendicular to said first plane and the hub been juxtaposed to said first plane.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to manually driven carrier vehicles, such as pushable carts, wheelchairs, barrows, carriages, and strollers and, more particularly, to a folding chassis therefor capable of traversing obstacles. 
       BACKGROUND OF THE INVENTION 
       [0002]    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. 
         [0003]    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. 
         [0004]    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 
       [0005]    The present invention generally focuses on a manually driven and foldable carrier vehicle capable of moving over uneven or spongy surfaces and surmounting obstacles. More particularly, the invention relates to a carrier having a chassis capable of climbing up and down (i.e. “walking”) over curbs, stairs, and other obstacles, 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. Furthermore, the present invention facilitates broader participation in outdoor activities by allowing physically challenged persons to go with the carrier anywhere easily. 
         [0006]    In general, in one aspect, a folding chassis includes a frame having a first plane, an arm with an axle, said arm pivotally attached to said frame; and a hub having a plurality of wheels and rotatably disposed onto said axle. Each of said plurality of wheels is attached to said hub rotatably around an axis parallel to said axle and said arm is configured to pivot between at least positions of said hub being generally perpendicular to said first plane and said hub been juxtaposed to said first plane. Various embodiments and implementations of this aspect of the invention include the following features: 
         [0007]    The arm is configured to pivot around an axis positioned at acute angles in relation to said first plane and to a plane perpendicular to the first plane. The plurality of wheels includes three wheels positioned symmetrically relative to said axle. The arm includes a guard member for preventing interference between a load and said plurality of wheels. The folding chassis may further include a handle configured to extend the frame and a detachable carrier with a rim and a brace, wherein said rim attachable to said handle at a plurality of levels and said brace is pivotally attachable to the frame. 
         [0008]    In general, in another aspect, the invention relates to a folding chassis including a frame having a first plane; an arm with an axle, said arm rotatably attached to said frame; a platform rotatably attached to said frame and linked to said arm and configured to pivot within a predetermined range relative to said first plane; and a hub having a plurality of wheels, said hub rotatably disposed onto said axle. Each of said plurality of wheels is rotatably attached to said hub around an axis parallel to said axle and said arm is configured to pivot between at least positions of said hub being generally perpendicular to said first plane and said hub being juxtaposed to said first plane. Various embodiments and implementations of this aspect of the invention include the following features: 
         [0009]    The arm is configured to pivot around an axis positioned at acute angles in relation to said first plane and to a plane perpendicular to the first plane. The folding chassis further includes a first support and a second support, wherein said first support attached rotatable to said frame, said second support attached rotatable to said platform and said first support, and said first and second supports configured to be fixable relative to one another in at least one position. The plurality of wheels consists of three wheels positioned symmetrically regarding said axle. The folding chassis may further include at least one caster configured to pivot relative to said platform and be fixable relative to said platform in at least one position. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]    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. 
           [0011]      FIG. 1  depicts a perspective view of an embodiment of a cart chassis in unfolded state according to present invention. 
           [0012]      FIG. 2  depicts a perspective view the embodiment shown in  FIG. 1  with the hub on one side not shown. 
           [0013]      FIG. 3  depicts a perspective view of an embodiment of the cart chassis according to present invention. 
           [0014]      FIG. 4  depicts a side view of the embodiment shown in  FIG. 3 . 
           [0015]      FIGS. 5A-7D  depict the hub in various phases of moving over obstacles, according to various embodiments of the present invention. 
           [0016]      FIG. 8  depicts a perspective view of an embodiment of the cart chassis in folded state according to present invention. 
           [0017]      FIGS. 9A and 9B  depict respectively bottom and front views of the embodiment shown in  FIG. 8 . 
           [0018]      FIGS. 10A and 10B  depict respectively bottom and front views in the folded state of the embodiment shown in  FIG. 1 . 
           [0019]      FIG. 11  depicts a perspective view of another embodiment of the cart chassis according to present invention. 
           [0020]      FIGS. 12A-12C  depict respectively perspective, side, and back views of the embodiment shown in  FIG. 11 . 
           [0021]      FIG. 13A  depicts a perspective view of an embodiment of a stroller chassis according to present invention in unfolded state with a bassinet installed. 
           [0022]      FIG. 13B  depicts a perspective view of another embodiment of the stroller chassis according to present invention in unfolded state with a bassinet installed. 
           [0023]      FIG. 14  depicts a perspective view of the embodiment shown in  FIG. 13A . 
           [0024]      FIGS. 15A-15C  depict perspective views of the embodiment shown in  FIG. 13A  at different stages of being folded. 
           [0025]      FIGS. 16A-16B  depict front and side views of the embodiment shown in  FIG. 15C . 
           [0026]      FIG. 17  depicts a perspective view of the embodiment shown in  FIG. 13B . 
           [0027]      FIGS. 18A-18C  depict perspective views of the embodiment shown in  FIG. 1B  at different stages of being folded. 
           [0028]      FIGS. 19A-19B  depict front and side views of the embodiment shown in  FIG. 18C . 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    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. 
         [0030]    Referring to  FIGS. 1-2  and  8 - 10 B, in one embodiment, a frame  110  of a cart  100  includes a lateral member  111  that support parallel studs  112  joined at ends opposite to the lateral member  111  by guides  113 , a latch  114  biased toward a handle  127 , arm brackets  115  and  116 , and support brackets  117  and  118 . Pivot axes of the arm brackets  115  and  116  may be positioned symmetrically and at acute angles to the frame  110  and the symmetry plane. The angles to the symmetry plane may be in a range from about 30 to about 75°, preferably about 60°, and the angle to the frame  110  may be in a range about from 15 to 55°, preferably 35°. An arm  119  with a cantilevered axle  120  and a guard  121  may be rotatably inserted into the arm bracket  115 . Correspondingly, an arm  122  with a cantilevered axle  123  and a guard  124  may be rotatably inserted into the arm bracket  116 . Hubs  125  with wheels  126  may be positioned onto the axles  120  and  123 . The handle  127  may slide trough the guides  113  such that holes  128  may be engaged by the latch  114  when the holes  128  align with corresponding holes (not shown) in the studs  112 . Similarly, pins  129  may engage the arms  119  and  122  at least in predetermined unfolded and folded positions through corresponding holes in the lateral member  111  and in the arms  119  and  122 . 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. 
         [0031]    A platform  150  of the cart  100  includes a bed  151  with a stop bar  152 , a pivot  153 , and bearings  154 . A support  155  may be inserted into corresponding holes in the bed  151  and a support  156  may be inserted into corresponding holes in the support brackets  117  and  118 . A link  157  may connect the support  155  with the support bracket  117 , while a link  158  may connect the support  156  with the pivot  153 . The bearings  154  may be positioned over the lateral member  111  allowing the platform  150  to rotate between positions when the stop bar  152  engages the arms  119 ,  122  and when the platform  150  touches the studs  112 . 
         [0032]    Referring to  FIGS. 3 ,  4  and  8 , in another embodiment, the cart  300  includes a detachable carrier  200  including a rim  201  with hooks  202  and attached pivotally a brace  203  as well as a container  205  (for clarity not shown in  FIG. 3  and shown schematically in  FIG. 4 ). The hooks  202  may be inserted into the holes  128  in the handle  127 . The brace  203  may be placed into nests  204  attached to the ends of the studs  112 . The container  205  may be one of collapsible baskets or folding bags known in the art. Referring to  FIG. 4 , numerals  201   a,    203   a , and  205   a  signify the most, and numerals  201   b,    203   b,  and  205   b  signify the least practically possible inclined positions of the carrier  200 . 
         [0033]      FIGS. 5A-7D  depict the chassis operation, according to some embodiments of the present invention, in various phases of traversing, e.g. rolling over, obstacles. On a flat surface, as shown in  FIG. 5A , the hub  125  may position with two of the wheels  126  supporting the load. When the hub  125  encounters a depression, as shown in  FIG. 5B , the front wheel  126  lowers into the depression and, if it deep enough, stops. Then the hub  125  rotates around an axis of the stopped wheel  126 ,  FIG. 5C , until the next wheel  126  lowers onto the surface as shown in  FIG. 5D . In doing so, the hub  125  rotated one third of a revolution as indicated by a direction of the arrow in the middle of the hub  125 . In effect, the hub  125  “walked” over the depression. Similarly, the hub  125  “walks” over an elevation,  FIG. 6A-D . In case the elevation is significantly higher then a half of diameter of the wheel  126 , the hub  125  may turn two thirds of the revolution as if the elevation of  FIG. 6  followed by the depression of  FIG. 5 . In much the same way, as shown in  FIGS. 7A-D , the hub  125  “walks” over a stairway rotating one third of the revolution for each step of the stairway. A pull force for either of the above described scenarios is a fraction of what it would have been for the conventional carts. This is particularly true when the chassis described herein is utilized for climbing the stairs as shown in  FIGS. 7A-D  where, even to overcome a ledge, the pull force is less than the cart weight. 
         [0034]    Referring to FIGS.  8  and  9 A- 9 B, in one embodiment of the present invention, folding the cart  300  entails rotating the platform  150  up to the studs  112 . By this action, the support  155  is pulled by the link  157  while the support  156  is pushed by the link  158 . In the folded position of the platform  150 , the supports  155  and  156 , as well as the links  157  and  158 , fit within the overall height of the platform  150 . Following that, the folding process includes disengaging the hooks  202  from the holes  128  they were inserted in, unlatching the handle  127  and sliding it until the latch  114  engaged the topmost holes  128 . After that, the brace  203  may be turned around in the nests  204  until the rim  201  with the folded/collapsed container  205  (not shown) would come to rest against the handle  127  opposite to the platform  150 . Finally, the pins  129  may be released to allow the arms  119  and  122  with the hubs  125  to be swung to positions where the hubs  125  may be generally juxtaposed to the studs  112  and the lateral member  111 . 
         [0035]    Referring to  FIGS. 10A and 10B , folding the cart  100 , although similar, may differ from disclosed above with respect to absence of the carrier  200 , which may allow the handle  127  to be retracted at any time after folding the platform  150 . 
         [0036]    Set forth for better clarity in symmetrical structures, like reference characters generally refer to like functioning mirrored parts as well as the same parts. Referring to  FIGS. 11 ,  12 A- 12 C, in another embodiment, a generally symmetrical framework  410  of a cart chassis  400  includes a frame  411  having end branches (not enumerated) disposed at acute angles to the symmetry plane and the framework  410 , a support bar  412  connecting the end branches and having bearings  413  and a bracket  414 , a support  415  fastened to the frame  411  and the support bar  412 , bearings  416  for attaching a handle  417 , and bearings  418  for attaching scissoring links  419  and  420  that may be latched when fully extended by a tab  421  of the link  420 . The handle  417  may pivot in the bearings  416  and be latched in fully extended position by a latch  422 . Arms  430  may be rotatably placed onto the end branches of the frame  411  between support bar  412  and stoppers  424  that affixed to the end branches and may be engaged by pivoting catches  431  of the arms  430 . A distal end  432  of each of the arms  430  may have a cantilevered axle  433  that supports a hub  440  with wheels  441 . A platform  450  includes an exterior rim  451  connected to the frame  411  by the links  419  and  420 , an inner frame  452  connected to the support bar  412  by the bearings  413 , and a support  453  placed rotatable into the inner frame  452  and connected by a link  454  to the bracket  414 . The links  419  and  420  serve additionally as guards for preventing interference between a load and the wheels  441 . 
         [0037]    Referring to  FIGS. 12A-12C , folding the cart  400  entails unlatching the links  419  and  420  by pulling the tabs  421  and rotating the platform  450  up to the framework  410 . By this action, the support  453  is pulled by the link  454  and the links  419 ,  420  are folded. In the folded position of the platform  150  the support  453  and the link  454  fit into the overall height of the platform  150 . Following unlatching the latch  422 , the handle  417  may be rotated up to the support bar  412 . Finally, the catches  431  may be released to allow the arms  430  with the hubs  440  to be swung to and locked again in positions where the hubs  440  may be generally juxtaposed to the framework  410 . A soft bag or a collapsible basket, which for better clarity neither shown nor discussed in this description, could fit into a gap between the framework  410  and the platform  450 . 
         [0038]    A folding chassis discussed above in connection with various embodiments of the invention, may be used in conjunction with a stroller. Referring to  FIG. 13A , in one embodiment, a stroller  500  includes a generally symmetrical chassis  510  and a seat for transporting a child, such as a bassinet  501 . The chassis  510  can be designed as universal and capable of fitting different seats and bassinets interchangeably.  FIG. 13B  shows a stroller  600  according to another embodiment of the invention, which includes a generally symmetrical chassis  610  and a seat represented by a bassinet  601 . As skilled artisans will readily recognize, there is a broad variety of mechanisms known in art for latching the seats  501 ,  601 , adjusting handles  511 ,  611 , and securing the chassis  510 ,  610  in unfolded position, suitable for use with the present invention. For better clarity they are neither shown nor discussed in this description. 
         [0039]    Referring to FIGS.  13 A and  14 - 16 B, in one embodiment, a platform  520  of the stroller chassis  510  includes a frame  521  with fixed gear segments  522  having bearings  523  for supporting a frame  530 . The frame  530  with elongated parts  531  includes pivots  532  that may be at acute angles relative to the chassis&#39; plane of symmetry and a plane perpendicular to it defined by the parts  531 . The angles may be in a range from about 30 to about 60°, preferably about 45°. Blocks  533  are attached to the parts  531  in such a way that bearings  534  coaxial with bearings  523  are centered at axes of the pivots  532 . The pivots  532  may support arms  540  with fixed gear segments  541  meshed with the gear segments  522 . Each of the arms  540  has a cantilevered axle  542  that supports a hub  550  with wheels  551 , which may have grooved hubs  552 . A cam  543  engages an internal mechanism (not shown) of the hub  550  for stopping rotation of the wheels  551  by interacting with the grooved hubs  552 . The internal mechanism, for example, may include a slider biased toward the cam  543  and connected to links capable of latching of grooves of the grooved hubs  552 . A brace  560  may be rotatably placed onto the frame  521  with bearings  561  coaxial to bearings  524 . A seat base  570  includes extensions  571 , bearings  572  that may pivot around a bar  535  of the frame  530 , a lateral member  573  that may pivot relative to the brace  560 , and a locking device  574 . The handle  511  may slide over the extensions  571 . A caster block  580  may pivot over the frame  521  and comprise a stopper  581  and casters  582 . 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. 
         [0040]    Conventionally, when operating a stroller on a rough terrain, people tend to lift front wheels of the stroller, which makes it similar to maneuvering a single axis cart. Subsequently,  FIGS. 5A-7D  may be attributed to the stroller operation, according to present invention, in various phases of rolling over obstacles in the “single axis” mode. 
         [0041]    Referring to FIGS.  13 B and  17 - 19 B, in another embodiment, a platform  620  of the stroller chassis  610  includes a frame  621  with a cranking mechanism  624  and spherical pivots  622  having bearings  623  for supporting a frame  630 . The frame  630  with elongated parts  631  includes bearings  634  coaxial with bearings  623  and pivots  632  that may be at acute angles relative to the chassis plane of symmetry and a perpendicular to it plane defined by the parts  631 . The angles may be in a range from about 30 to about 60°, preferably about 45° to that plane, which, in turn, may be at an angle in range from about 0 to about 20°, preferably about 8° to the elongated parts  631 . The pivots  632  may support arms  640  with spherical bearings  641 . Links  642  constructed for swiveling may connect the spherical pivots  622  of the platform  620  with the spherical bearings  641  of the arms  640 . Each of the arms  640  may have a cantilevered axle  643  that supports a hub  550  with wheels  551 , which may have grooved hubs  552 . A cam  644  may engage an internal mechanism (not enumerated) of the hub  550  for stopping rotation of the wheels  551  by interacting with the grooved hubs  552 . The internal mechanism, for example, includes a slider biased toward the cam  644  and connected to links capable of latching of grooves of the grooved hubs  552 . A brace  660  may be rotatably placed onto the frame  621  with bearings  661  coaxial to bearings  624 . A seat base  670  includes an extension  671 , a bearing  672  that may pivot around a lateral part of the frame  630 , a bearing  673  that may pivot relative to the brace  660 , and a locking device  674 . The handle  611  may hinge in the extension  671 . Mirrored caster blocks  680  may pivot on the frame  621 , each including a linkage  681  and a caster  682 . The linkages  681  may connect to the cranking mechanism  624  capable of self latching at least in unfolded position. 
         [0042]    Referring to  FIGS. 15A-16B , in one embodiment of the present invention, folding the stroller chassis  510  intails unlocking the locking device  574  and pushing the handle  511  towards the platform  520 . By this action, the frame  530  and the brace  560  are pivoted at the bearings  523  and  524  respectively. The arms  540  with the gear segments  541  rotate around the gear segments  522  bringing the hubs  550  generally to a common plane parallel to the plane defined by the parts  531 . In this embodiment, angles of rotation of the frame  530  and the arms  540  preferably about 94° and 109° respectively. The caster block  580  may be rotated and the handle  511  may be slid into folded positions. 
         [0043]    Referring to  FIGS. 18A-19B , in another embodiment, folding the stroller chassis  610 , intails unlocking the locking device  674  and pushing the handle  611  towards the platform  620 . By this action, the frame  630  and the brace  660  are pivoted at the bearings  623  and  624  respectively. The arms  640  with the spherical bearings  641  rotate around the pivots  632  bringing the hubs  550  generally to a common plane parallel to the plane defined by the parts  631 . In this embodiment, angles of rotation of the frame  630  and the arms  640  preferably about 96° and 109° respectively. The cranking mechanism  624  may be rotated pushing the linkages  681  outward that may cause the caster blocks  680  to be rotated into folded positions. The extension  671  may be slid and the handle  611  rotated into folding position as well. 
         [0044]    Consequently, the present invention provides the improved folding chassis for handling all kinds of terrain including curbs and stairs. Furthermore, the invention provides that such chassis folds relatively flat for better handling and storage in the folded state. Moreover, the present invention facilitates greater self sufficiency for physically challenged persons by easy of use including folding/unfolding without detaching any parts. 
         [0045]    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. 
         [0046]    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. 
         [0047]    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. The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one”. As used herein, the term “about” refers to a +/−10% variation from the nominal value. It is to be understood that such a variation is always included in any given value provided herein, whether or not it is specifically referred to. 
         [0048]    As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. It should also be understood that, unless clearly indicated to the contrary, in any methods disclosed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited. In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively