Abstract:
A convertible cart a back frame assembly, a collapsible platform pivotally attached to the back frame assembly, a plurality of wheels rotatably attached to at least one of the back frame assembly and the collapsible platform, and a collapsible container attached to the back frame assembly and the collapsible platform. The back frame assembly, the collapsible platform and the collapsible container define a partially enclosed region.

Description:
RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/474,344 entitled “Shopping Cart and Platform Cart”, filed Jun. 2, 2003, hereby fully incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to foldable four wheeled handcarts that can be easily converted to a four-wheeled container cart. More particularly, the invention pertains to a convertible carrier that can be used as a platform cart, a shopping cart or utility cart, and then collapse the carrier to compact dimensions for storage and/or transport.  
       BACKGROUND OF THE INVENTION  
       [0003]     Various types of handcarts and dollies have been developed to assist in moving large items from one location to another. Such handcarts are used in factory, office, warehouse, store and home environments and can be of various size and shape, dependent upon the load that is to be transported. However, such handcarts are not practical for transporting numbers of smaller items at one time. For example, use of a handcart or dolly is not an efficient or practical way to transport groceries, laundry, toys and the like. A cart or wagon used to transport numbers of smaller objects generally has sidewalls and a closed bottom forming a container in which the smaller items cant be placed.  
         [0004]     At different times, it may be necessary to transport a mixture of items; both large items and a number of smaller items. As a result, more than one type of handcart may be required to move the various sized items. It would be advantageous to have one such handcart that could be easily converted from one type of handcart resembling a dolly or platform cart, to a handcart more closely resembling a shopping cart or laundry cart. More particularly, it would be advantageous to have one handcart that could be configured to transport most any type of item. Further, it would be desirable if the handcart could also be folded into a compact configuration for storage, for hand carrying, or for transport in a vehicle, such as an automobile trunk.  
         [0005]     A variety of foldable, wheeled carts have been developed in order to try to meet the needs of the marketplace. Examples of prior art foldable handcarts of varying description may be found in U.S. Patent Nos. 2001/0011802A1 to Meabon; U.S. Pat. No. 2,767,996 to Seyforth; U.S. Pat. No. 3,194,576 to Kunkle; U.S. Pat. Nos. 3,743,312; 4,136,889 to Middleton; U.S. Pat. No. 4,448,434 to Anderson; U.S. Pat. No. 4,570,961 to Chateauneuf et al.; U.S. Pat. No. 6,053,515 to Kelley; U.S. Pat. No. 6,152,462 to Barrett; U.S. Pat. No. 6,267,393 to Mengrone et al.; and U.S. Pat. No. 6,419,244 to Meabon; all of which are hereby fully incorporated by reference.  
         [0006]     Prior art wheeled handcarts typically include a pair of upright frame members, each having a handle and a wheel at opposite ends. Many of these carts have only two wheels, which necessitates balancing the load on the cart while wheeling the cart. The handles and wheels extend in the same direction from the upright frame. A load carrying plate or bracket extends from the wheel-end of the frame members, in the direction opposite the wheels and handles. There may be a number of braces extending between the upright frame members to provide additional support to the load being transported on the handcart or dolly.  
         [0007]     To be able to use the upright handcart as a transporting receptacle, the handcart is often placed in a horizontal position and additional structures must be added to the basic handcart. For example, in U.S. Patent Nos. 2001/0011802A1 and U.S. Pat. No. 6,419,244 an additional wheel must be added to the cart chassis, if the cart is to be used in the horizontal position as a transport container. In addition, a handle may need to be added so that the handcart can be maneuvered when the handcart is oriented in a horizontal configuration.  
         [0008]     In U.S. Pat. No. 3.743,312, a dolly-type handcart can be reconfigured to a wheelbarrow-type transport container by the addition of the wheelbarrow tub. The wheelbarrow tub may already have a wheel secured to its forward bottom section or the wheels of the handcart can be reconfigured and used to drive the cart.  
         [0009]     U.S. Pat. No. 4,136,889 similarly provides for a dolly-type handcart that has upright frame members and bars that can be adjusted to effectively shift the position of the wheels when the reconfigured frame is in a horizontal position. A receptacle can then be mounted on the horizontal frame and the unit can be used as a wheelbarrow-type cart.  
         [0010]     A dolly-type handcart in the prior art that is collapsible and convertible to a container-type cart is described in U.S. Pat. No. 4,448,434. The dolly-type handcart also has two elevated, load-carrying brackets connected to and positioned between the upright frame members of the cart, proximate the handles. When in use, the brackets are rotated to extend outwardly from the upright frame members on the side opposite the handles and wheels. Each bracket has an extension pivotally attached to the bracket such that the extension nests over the upper surface of the bracket. A soft container such as a sack can be positioned over the bracket and held in place by the bracket extension.  
         [0011]     The above-noted dolly-type handcarts, although convertible to horizontally-oriented container-type carts, require various additional structural pieces to effect the conversion. The added pieces can include wheels or wheel assemblies, a receptacle, a handle and the like. In addition, the dollies and some of the container carts have only two wheels. Therefore it is necessary to be able to balance the load on the dolly or in the receptacle when transporting the load.  
       SUMMARY OF THE INVENTION  
       [0012]     In preferred embodiments of the invention, a collapsible four-wheeled container cart is convertible into a four-wheeled platform cart (or vice-versa), without the addition of structural parts or the need for tools to effect the conversion. The platform of the cart is hingedly attached to a back frame assembly, the platform being supported by two wheel assemblies distal to the back frame assembly.  
         [0013]     The back frame assembly, comprising an extended U-shaped handle, two vertical arms positioned proximate the outer surface of the handle upright members and connected to the handle via a top plate, and a back panel positioned intermediate the two vertical arms, has a spaced-apart pair of wheels at its lower end. The bottom of a leather or fabric container is removably attached to the platform of the cart.  
         [0014]     The container has a side support that diagonally traverses the container sides and crosses the front of the container. The side support is hingedly attached to the cart back frame assembly such that when the bottom of the container is disengaged from the platform, collapsed, and folded vertically proximate the back frame assembly, the side support provides some support to keep the fabric container in place.  
         [0015]     The container cart is thus converted into a platform cart. To convert the platform cart to its storage configuration, the platform is folded up to a vertical position proximate the back frame assembly, with the folded container positioned intermediate the back frame assembly and the vertically positioned platform.  
         [0016]     A feature and advantage of the invention is that the conversion of the container cart to a platform cart, or from a platform cart to a container cart, requires no tools and no additional parts. The convertible cart is completely self-contained. Hence, the cart can be converted between its two operational configurations at any time and at any place.  
         [0017]     A further feature and advantage is that the cart is collapsible for transport or storage without the need of tools to effect the change in configuration. The collapsed cart can fit inside the typical automobile trunk and requires little storage space.  
         [0018]     A further feature and advantage is that the cart can be made of plastic material, which weighs less than metal, does not rust, and does not make noise during use as compared to metal/wire container/shopping carts. The use of plastic results in an easily transportable, relatively lightweight cart.  
         [0019]     A further feature and advantage is that the platform cart and the container cart configurations have four wheels and do not require balancing the load on just two wheels during transport.  
         [0020]     A further feature and advantage is that the capacity of the container on the cart is greater than the capacity of the average collapsible shopping cart.  
         [0021]     A further feature and advantage of the invention is that the mechanisms whereby the container cart is formed or the platform cart is collapsed are easily deployed. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0022]      FIG. 1  is a perspective view of a collapsible cart in an unfolded configuration.  
         [0023]      FIG. 2  is a perspective view of the cart in a collapsed configuration.  
         [0024]      FIG. 3  is a perspective view of the collapsible cart in a platform cart configuration.  
         [0025]      FIG. 4  is an exploded view of an undersurface of a platform for the collapsible cart.  
         [0026]      FIG. 5  is a perspective view of a locking mechanism when the collapsible cart is in an operational configuration.  
         [0027]      FIG. 6  is a side plan close-up view of a top section of the locking mechanism.  
         [0028]      FIG. 7  is a close-up side plan view of a bottom section of the locking mechanism.  
         [0029]      FIG. 8  is a side plan view of the locking mechanism when the collapsible cart is in the collapsed configuration.  
         [0030]      FIG. 9  is an exploded view of the collapsible cart.  
         [0031]      FIG. 10  is a perspective view of a top plate and a lock assembly for the collapsible cart.  
         [0032]      FIG. 11  is a close-up exploded perspective view of the lock assembly. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0033]     Referring to  FIGS. 1-3 , the invention includes a collapsible cart  1  that is configured as a container/shopping cart and, alternatively, as a platform cart. The collapsible cart  1  comprises a platform  20 , a flexible container  10  and a back frame assembly  30 .  
         [0034]     A bottom of the container  10  rests on the top of the platform  20  when the container  10  is extended and operational. When the container  10  is not operational, the container  10  is folded and stored vertically, abutting the back frame assembly  30 . When the cart  1  is collapsed for storage and/or transport, the platform  20  folds up to a vertical position, abutting the back frame assembly  30  and sandwiching the folded container  10  therebetween.  
         [0035]     The platform  20  shown generally in  FIGS. 1-4  has a pair of wheel assemblies  40  attached to the underside of the platform  20 , distal to the back frame assembly  30 . Each wheel assembly is comprised of a left swivel wheel  41 , a right swivel wheel  42 , a wheel support bracket  43  and a connector pin  44 . The wheel support bracket  43  is positioned intermediate the left swivel wheel  41  and the right swivel wheel  42  such that the hole in the wheel support bracket  43  aligns with the hole in the center of the left swivel wheel  41  and the hole in the right swivel wheel  42 . The pin  44  passes through the left swivel wheel  41 , the wheel support bracket  43  and the right swivel wheel  42 , such that the wheels are concentrically aligned. A press-fitted cap (not shown) is preferably affixed onto the pin  44  to secure the various parts of the wheel assembly into a complete unit.  
         [0036]     The underside of the platform  20  has two pins  240  integrally formed with the platform  20 , one pin  240  in each corner that is proximate the distal edge of the platform  20 . The pins  240  are positioned substantially perpendicularly to the underside of the platform  20 . The tubular end of the wheel support bracket  43  of the wheel assembly  40  is placed over a pin  240  and is secured with a press-fitted cap.  
         [0037]     Two spaced-apart pivot-bars  150  are located along either side of the length of the platform  20 , on the underside of the platform  20 . Two spaced apart connecting bars  160  are oriented perpendicularly to the pivot-bars  150 , between the two pivot-bars  150 . Screws  260  affix opposite ends of each connecting bar  160  to the pivot-bars  150 . One connecting bar  160  is preferably located proximate the end of the pivot-bars  150 , opposite the wheeled edge of the platform  20 . The second connecting bar  160  is preferably located proximate the wheeled edge of the platform  20  as compared to the first connecting bar  160 . A total of four screws  250 , two in each connecting bar  160 , preferably join each connecting bar  160  to the underside of the platform  20 .  
         [0038]     Each pivot bar  150  contains a tab extension located at the end of the bar distal to the wheeled end of the platform  20 . The tab contains hole  152 . In addition, a hole  151  is located in the side of each pivot-bar  150 , between the two connecting bars  160 . Hole  21  is located on each side panel of the platform, distal from the wheeled end of the platform  20 .  
         [0039]     As shown in  FIG. 9 , the back frame assembly is comprised of a back frame panel  90 , two vertical arms  120 ,  130 , and an extended U-shaped handle  60 . The back panel  90  is positioned intermediate the two vertical arms  120 ,  130 , and affixed to the arms. A bracket  290  at the top of each vertical arm  120 ,  130 , is aligned with a hole at the top of the back panel  90 , and a screw  91  is threaded through the panel hole and the bracket, thus securing the back panel  90  to each of the vertical arms  120 ,  130 .  
         [0040]     Each vertical arm  120 ,  130  contains an integral pin located at the base of the arms  120 ,  130 , and oriented perpendicularly to the outer surface of the arms  120 ,  130 . A rear wheel  50  is inserted over each pin and secured to the arms  120 ,  130  via a press-fitted closing cap. The ends of a stop-bar  170  are inserted into cavities formed in the interior side of the base of the two vertical arms  120 ,  130 . The lower portion of the back panel  90  is attached to the stop-bar  170  via two screws  92 .  
         [0041]     The extended U-shaped tubular handle  60  is attached to the two vertical arms  120 ,  130  via brackets  140  affixed to the top and extending from the vertical arms  120 ,  130 . The free ends of the brackets  140  are secured to the top plate  80  portion of the U-shaped handle via a set of screws.  
         [0042]     As shown in  FIGS. 5, 6 , and  9 , two guiders  270  are inserted into the lower tubular ends of handle  60 , further extending the length of the handle  60 . Two pins  280  are press-fitted into holes  63  in the handle  60  and pass through the slots  271  at the top of the guiders  270 , thus securing the guiders  270  to the extended handle  60 .  
         [0043]     As best shown in  FIG. 7 , tabs at the lower end of the guiders are connected to hinges  100  by pins passing through holes  101 . Alternatively, the upright members of the handle  60  can be extended to connect to hinges  100 . The holes  102  at the lower end of the hinges are aligned with holes  152  of the pivot-bars  150  and secured by pins, thus connecting the hinges  100  to the pivot-bars  150  and, consequently, to the platform  20 . This last link completes the connection of the handle  60  to the platform  20 , via the guiders  270 , the hinges  100 , and the pivot-bars  150 . The back panel  90  contains two cut-outs at its lower edge to accommodate the hinge  100  portion of the connective linkage. This entire mechanism is best shown in  FIG. 5 .  
         [0044]     As best shown in  FIGS. 10 and 11 , the upright members of U-shaped handle  60  pass through two holes or round openings in the top plate  80 , such that movement of the members is allowed through the openings. The top plate  80  is secured to the two arms  120 ,  130  by two brackets  140  and screws. The top plate  80  contains an integral grab handle  81  that provides support when the platform cart is collapsed closed.  
         [0045]     A locking mechanism is attached to the top of the right opening of the top plate  80  and includes a lock  110 , a torsion spring  190  and a molded steel plate  200 . The torsion spring  190  creates a counter-clockwise torsion force that keeps the molded steel plate  200  in constant contact with a surface of the handle  60  during opening and closing of the cart. A shoulder screw  310  connects the lock  110  and the torsion spring  190 , allowing the lock  110  to rotate about its vertical axis. The locking mechanism secures the platform  20  in position when the cart is unfolded and operational, or collapsed for storage and/or transport.  
         [0046]     To open the cart  1  from its collapsed (storage) configuration, the lock  110  is rotated about its vertical axis, disengaging the molded steel plate  200  from contact with an upright member of the handle  60 . The handle  60  is then pulled vertically in an upward direction, moving the upright members of the handle  60  upward through the openings in the top plate  80 . The linear motion of the handle is converted to radial motion as the upright members of the handle  60  pull up the guiders  270 , which in turn pull up the top end of the hinges  100  causing the elbow of the hinges to pull backwards and slightly upwards, resulting in the platform  20  unfolding to a horizontal position.  FIGS. 8 and 5  show the configuration of the handle  60  and the attached linkages when the platform  20  is in a horizontal, operational position and when the platform  20  is in a vertical, storage position.  
         [0047]     To secure the cart  1  in the operational configuration, when the cart  1  is unfolded, the molded steel plate  200  is automatically inserted into slot  62  on the handle  60 , by the torsion force created by the spring  190 . Concurrent with the platform unfolding to a horizontal position, the container  10 , along with its side support  180 , also unfolds to its upright, operational position. The bottom of the container  10  is removably attached to the platform  20 , such that when the platform  20  unfolds, the container  10  also unfolds and opens by following the platform  20 . The container  10  is connected to the back frame assembly by way of the two vertical arms  120 ,  130 . Openings in the right and left side edges of the container align with openings in the vertical arms  120 , 130  and pins or screws connect the two surfaces.  
         [0048]     The container  10  further has a side support  180  diagonally traversing the sides and crossing the front of the container  10 . The side support  180  is pivotably coupled to the base of the arms  120 ,  130  and provides structure to the fabric or leather container  10 . The operational configuration for the container cart is shown in  FIG. 1 . To configure the collapsible cart  1  into a platform cart, the container bottom is disengaged from the platform  20  and folded up, such that the folded container and side support are positioned vertically abutting the back frame assembly  30 .  
         [0049]     The platform cart  1  is collapsed for storage by pulling the lock  110 , such that the molded steel plate  200  disengages from slot  62 . The handle  60  is pushed downward, such that pin  280  reaches and engages the lower surface of slot  271 . The downward force is then transmitted from slot  271  to the guiders  270  and on to the hinges  100 , resulting in the hinges  100  moving forward. The hinges  100  are attached to the pivot-bars  150 , and the downward and forward force causes the pivot-bars to pivot around point  21  and lift the platform to an upright position abutting the back frame assembly  30 .  FIG. 8  shows the platform cart in the collapsed, upright position, such that the change in position of the handle  60 , guiders  270 , hinges  100  and platform  20  are demonstrated, as compared to  FIG. 5 . The cart  1  is locked in this position via inserting the molded steel plate  200  into slot  61 .  
         [0050]     The cart of the present invention has important advantages over the prior art carts. The cart is convertible from the storage, to the container cart, to the platform cart configurations without the need of tools or the need for additional parts. The cart may be made of various plastic components, making the cart reasonably lightweight so that it can be carried or rolled to its destination for use or storage. And, in addition, the cart easily transitions among the three configurations.  
         [0051]     It is contemplated that features disclosed in this application, as well as those described in the above applications incorporated by reference, can be mixed and matched to suit particular circumstances. Various other modifications and changes will be apparent to those of ordinary skill.