Abstract:
A modular shoe separates into components. The components may be interchangeable to provide versatility without requiring a large number of single use shoes. Each shoe component may also be collapsible to provide for convenient packing in a travel bag or other location where space is limited.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   The present application is a divisional of U.S. patent application Ser. No. 11/368,768, filed Mar. 6, 2006 now U.S. Pat. No. 7,284,344, which is a continuation of U.S. patent application Ser. No. 10/844,302, filed May 12, 2004, issued as U.S. Pat. No. 7,010,872, which claims the benefit of the filing date of U.S. Provisional Application No. 60/471,418, filed on May 16, 2003, the entire disclosures of which are hereby incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   A pair of shoes is typically adapted for a specific use, with a person owning a number of different types of shoes for different purposes. 
   For example, different shoes may be used for walking, for hiking, for athletic activities, or for formal occasions. Even within each type of shoe category, a number of pairs of shoes may be required, such as a pair of hiking shoes suitable for snow, a pair for wet terrain, and a lightweight pair designed for greater comfort on long hikes over dry terrain. Similarly, formal footwear may include different colors and styles of shoes for different clothing, and different types of occasions. 
   The useful variety of available footwear poses particular problems for the traveler, who is frequently faced with the task of packing a variety of gear into one or two bags suitable for carrying. This problem is made worse by the fact that each shoe may be bulky and rigid, requiring significant space in a travel bag, and adding significant weight to the bag once it has been packed. 
   There remains a need for footwear that offers versatility to travelers in a compact form. 
   SUMMARY OF THE INVENTION 
   A modular shoe is provides which separates into components. The components may be interchangeable to provide versatility without requiring a large number of complete shoes. Each subcomponent may also be collapsible to provide for convenient packing in a travel bag or other location where space is limited. 
   In one embodiment, the shoe of this invention comprises the following components: a foot enclosure for receiving a foot, a chassis adapted to fit beneath the foot enclosure, and a shell surrounding the chassis and foot enclosure for engaging the foot while in use. These components are removable and replaceable to provide a variety of options for the wearer. 
   In another embodiment, the modular shoe of this invention includes a foot enclosure, a chassis and a shell, wherein the lower surface of the chassis has treads which protrude through one or more openings in the bottom of the shell. 
   In a further embodiment, the shoe of this invention includes a weatherproof barrier for protecting the foot of the wearer against adverse weather conditions, such as those resulting from rain, water, mud or snow. 
   In accordance with another embodiment of the present invention, an article of footwear is provided. The article of footwear comprises a shell and a chassis. The shell provides an opening for receiving a foot therein. The shell includes a ground contacting surface on a bottom thereof and a cinching mechanism for securing the foot within the opening. The chassis is adapted for removable insertion within the opening of the shell. The chassis provides a support surface for the foot, a rear surface connected to a heel section of the support surface, and a fold line for collapsing the chassis by folding along the fold line. 
   In one alternative, the fold line is disposed between the rear surface and the support surface. In another alternative, the rear surface of the chassis includes a protrusion thereon positioned for a facing arrangement with a rear portion of the shell. In this case, the rear surface of the chassis may comprise a rigid back surface that is collapsible along the fold line so that the chassis may be removed from the shell. 
   In accordance with a further embodiment of the present invention, an article of footwear is provided. The article of footwear includes a chassis and a shell. The chassis provides a support surface for a foot. The chassis including a protrusion thereon. The shell surrounds the chassis, and is adjustable to maintain the chassis in operative engagement with the foot while in use. The shell includes an opening in a heel area thereof. The chassis and the shell are removable and replaceable with respect to one another. The protrusion is suitable for gripping to apply a force to the chassis to disengage the chassis from the shell. The opening in the heel area of the shell is configured to engage with the protrusion on the chassis when the chassis is engaged with the shell. 
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     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objects and advantages of the invention will be appreciated more fully from the following further description thereof, with reference to the accompanying drawings, wherein: 
       FIG. 1  is a perspective view of a modular shoe. 
       FIG. 2  is a bottom view of a modular shoe. 
       FIG. 3  is a perspective view of modular shoe with a foot enclosure partially disengaged, depicting the disengagement of the shoe by a user. 
       FIG. 4  is a perspective view of a modular shoe without a foot enclosure. 
       FIG. 5  is a perspective view of a modular shoe with a chassis partially disengaged and depicting disengagement of the chassis. 
       FIG. 6  is a bottom view of a modular shoe with a chassis partially disengaged. 
       FIG. 7  is a top front view of the components of a modular shoe. 
       FIG. 8  is a front side view of components of a modular shoe. 
   

   DETAILED DESCRIPTION 
   To provide an overall understanding of the invention, certain illustrative embodiments will now be described, including a modular shoe with three components: a foot enclosure, a chassis, and a shell. However, it will be understood that the footwear systems described herein may have utility as a different number of components and subcomponents, such as treads, shell, chassis, and foot enclosure, and may employ components and subcomponents adapted for any number of aesthetic or functional purposes. All such footwear designs are intended to fall within the scope of the systems described herein. 
     FIG. 1  depicts a modular shoe. The shoe  100  may include a shell  102  with a cinching mechanism  104 , a chassis (not visible), and a foot enclosure  106 . 
   The shell  102  may be formed of conventional shoe materials, such as leather, vinyl, suede, woven material, rubber, or plastic, or combinations of these. The materials for the shell  102  may also be selected according to conventional footwear design constraints including aesthetics, durability, flexibility, or comfort. In general, the shell  102  may be any component providing an exterior surface to the shoe  100  described herein. Thus a number of shells may be carried by a traveler, with each shell serving a particular aesthetic or functional role for the traveler. 
   The cinching mechanism  104  may be shoe laces, Velcro straps, buckles or any other device or devices for securing the shoe  100  about the foot of a wearer. The cinching mechanism  104  of the shell  102  may be tightened to securely engage the shell  102 , the foot enclosure  106 , and the chassis about the foot of the wearer while the shoe  100  is in use. The cinching mechanism  104  may be loosened to permit removal and disassembly of the shoe. 
   The chassis, which will be discussed in further detail below, may provide a supportive bottom surface beneath the foot enclosure  106 , such as a rigid, semi-rigid, or flexible support surface, and may include padding along its top surface for the comfort of a wearer of the shoe  100 . In general, the chassis may be any component providing rigid support to the overall shoe  100  described herein. 
   The foot enclosure  106  may be positioned within the shell  102 , and is generally adapted to receive a foot of a wearer. In general, the foot enclosure  106  may be any component adapted to receive a wearer&#39;s foot. Where the foot enclosure  106  comes directly in contact with the foot, the foot enclosure  106  may have an interior surface comfortable for such direct contact. The foot enclosure  106  may include a padded bottom surface. The foot enclosure  106  may be formed of any suitable material including natural or synthetic woven materials, breathable membranes that are permeable to water vapor but not liquid, and/or an elastic material that stretches to adapt to the shape of a foot. The foot enclosure  106  may also include additional padding or a wear guard directly beneath the cinching mechanism  104  to provide additional comfort at this pressure point within the shoe, and/or to reduce wear on the foot enclosure  106  during repetitive tightening and loosening of the cinching mechanism  104 . 
   Although it is expected that the foot enclosure  106  will remain fixed within the shell  102  when a user&#39;s foot is inserted into and removed from the shoe  100 , the foot enclosure may further include a zipper (not shown) or other mechanism to facilitate insertion and removal of a foot directly from the enclosure  106  so that the foot enclosure may additionally serve as a slipper apart from the shell  102 . In one embodiment, the foot enclosure  106  may be positioned above the chassis. However, it will be appreciated that the foot enclosure  106  may instead enclose the chassis, in which case the chassis would preferably present an upper surface that comfortably engages the foot of the wearer. Further, while the foot enclosure  106  is depicted as a slipper or sock-like component that encloses most of a foot, other types of foot enclosures may be used, such as a strap or band of elastic material, a sandal-like configuration that slides between the toes, around the ankle, or some other portion or portions of the foot, or any other arrangement that operates to hold the foot securely within the shoe  100 . All such structures and configurations are intended to fall within the scope of the term “foot enclosure”  106  as that term is used herein, except where specifically described otherwise. 
   Each of the foot enclosure  106 , the chassis, and the shell  102  may be removable and replaceable so that the shoe  100  may be disassembled and reassembled. Or, one of the components may be removed and replaced with a different component. For example, a user may change from a brown shell  102  to a black shell  102  to match a change in clothing. Or the user may change to a chassis with a more aggressive tread before an off-road hike. Or the user may insert a new foot enclosure  106  or chassis after a day&#39;s use. 
   It will be readily appreciated that any number of different or additional components may be included with the shoe  100  described herein, and that the components may be differently arranged. For example, the chassis may be positioned within the foot enclosure  106  rather than between the foot enclosure  106  and the shell  102 , with suitable adaptations of padding, surface materials, and attachment mechanisms. All such arrangements are intended to fall within the scope of the footwear described herein. 
     FIG. 2  is a bottom view of a modular shoe. The shoe  200  may be the shoe  100  described above with reference to  FIG. 1 . As visible from this perspective of the shoe  200 , the chassis  202  may form a portion of a bottom surface of the shoe  200 . The shoe  200  may include treads  204  on the chassis  202  and/or treads  206  on the shell  208 . The treads  204  may be of various shapes and sizes, with various gripping surfaces according to intended uses of the shoe  200 . For example, the treads  204 ,  206  may be adapted for wet slippery surfaces as in a deck shoe, for comfortable use on dry level surfaces as in a walking shoe, or for traction on off-road terrain as in a hiking shoe. The bottom surfaces of the shell  208  and the chassis  202  may be formed of any conventional material used in a shoe outsole, such as molded rubber or plastic, or any other material suitable for use in a shoe outsole and treads. The chassis  202  may be friction-fit into the shell  208  or otherwise securely but removably affixed to the shell  208 , along with a gasket to seal a seam between the chassis  202  and the shell  208  to render the seam watertight. 
   It will be appreciated that, although not depicted here, in certain embodiments more or less of the surface of the bottom surface of the shoe  200  may be formed from the chassis  202 . In certain embodiments, the chassis  202  may not protrude through the shell  208  at all, with the shell  208  forming the entire bottom surface of the shoe  200 . However, combining treads  204  with the chassis  202  in an integrated subcomponent permits the nature of the treads  204  to match any interior padding in the chassis  202  so that both the interior cushioning and the treads may be conveniently matched to a particular use of the shoe, such as hiking. 
     FIG. 3  depicts a modular shoe with a foot enclosure partially disengaged. The shoe  300  includes a shell  302 , a chassis  304 , a foot enclosure  306 , a first attachment device  308 , and a second attachment device  310 . A tool  312  that mates with a groove  314  in the shell  302  may be provided to assist with disassembly of the shoe  300 . The shoe  300  may be any of the shoes described above. 
   The first attachment device  308  and the second attachment device  310  may include any mechanism for securing the foot enclosure  306  within the shell  302  and/or the chassis  304 . For example, the devices  308 ,  310  may include mating Velcro strips on the foot enclosure  306  and the shell  302 , or a similarly positioned button and button hole, or a button and snap, or other device or mechanism for securing the foot enclosure  306  within the shoe  300 . Once the devices  308 ,  310  have been detached from one another, the foot enclosure  306  may be withdrawn from the shell  302  as depicted. When the foot enclosure  306  is inserted into the shell, the devices  308 ,  310  may be reattached to secure the foot enclosure  306  in place. Although the precise placement and nature of the devices  308 ,  310  is not essential, it is preferred that the devices  308 ,  310  are of the same type, and in the same location for different shells and foot enclosures, so that the modular nature of the shoe  300  is maintained. 
   The tool  312  may provide a surface against which a downward pressure may be conveniently exerted while pulling upward to withdraw the foot enclosure  306  from the shell  302 . The tool  312  may be generally U-shaped, and the groove  314  in a heel area of the shell  302  may mate with the tool  312  so that the tool  312  horizontally slides onto and off of the groove  314 . Any other tool or technique that provides a suitable surface for applying force counter to withdrawal of the foot enclosure  306  may be similarly employed. 
     FIG. 4  depicts a modular shoe without a foot enclosure. The shoe  400  may be any of the shoes described above, and may include a chassis  402 , a tab  404 , and a shell  406 . With the foot enclosure (not shown) removed, an upper surface of the chassis  402  is visible. The upper surface of the chassis  402  may be suitably padded, such as by provided extra padding in the heel area to absorb shock during walking. The tab  404  or other protrusion may extend from the chassis  402  in a manner suitable for gripping and pulling to withdraw the chassis  402  from the shell  404 . In lieu of a tab  404 , the protrusion may include a hook or other mechanical device suitable for gripping and withdrawal with an appropriate tool, although such a mechanical protrusion would preferably be positioned and configured to avoid discomfort to a wearer of the shoe  400 . 
     FIG. 5  depicts a modular shoe with a chassis partially disengaged. The shoe  500  may be any of the shoes described above, and may include a shell  502  with a groove  504  in the heel area and a chassis  506  with treads  508 , a gasket  510 , and a tab  512 . A tool  514 , such as the tool  312  described above with reference to  FIG. 3 , may be provided that mates with the groove  504  to assist with disassembly of the shoe  500 . 
   The treads  508 , as noted above, may be configured to protrude through openings (not shown) in the shell  502  to provide a gripping surface while the shoe  500  is in use. As noted above, the tread type may vary according to an expected use for the chassis  508 , such as for sporting, outdoor, casual, or formal use. Any suitable padding or cushioning, such as foam or an air or gas bladder (or interconnecting or isolated groups of bladders) may be included in the chassis  506  to cushion areas, such as the heel for the user&#39;s foot. 
   The chassis  506  may also include uniform or varying reinforcements, or layers of stiff material, in order to impart a desired degree of stiffness to the entire chassis  506 , and individual areas thereof. For example, a stiff heel area may be desired to distribute the shock across a padded area of the chassis  506  when the heel strikes a surface during walking, whereas a more flexible area may be desired further forward in the shoe where the foot naturally flexes during walking motion. 
   The gasket  510  may be, for example, a rubber bead attached to the chassis  506  where the chassis  506  mates with the shell  502 . The frictional engagement of the chassis  506  to the shell  502  may secure the chassis  506  within the shell  502 , and provide a watertight seal to a bottom surface of the shoe  500 . 
   The tab  512  may align and further secure the chassis  506  within the shell  502  by mating with a corresponding slot (not shown) in the shell  502 . 
     FIG. 6  is a bottom view of a modular shoe with a chassis partially disengaged. The shoe  600  may be any of the shoes described above. From this perspective, two openings  602 ,  604  are visible in the shell  606 , once the chassis  608  has been removed. The openings  602 ,  604  are configured to receive tread portions of the chassis  608 , and include edges that mate with the gasket (not shown) on the chassis  608 . It will be appreciated that other arrangements of this construction are possible. For example, more or less openings may be provided in the shell  606 , and other securing and sealing mechanisms may be used, such as a gasket on the shell  604  instead of the chassis  608 . 
     FIG. 7  is a top front view of components of a modular shoe. The shoe  700  may be any of the shoes described above, and may include a shell  702 , a chassis  704 , and a foot enclosure  706 . Certain features of the shoe  700  are now described in more detail. 
   From this perspective, a slot  708  is visible on the rear surface of the shell  702 . A corresponding tab  710  is visible on the chassis  704 . In operation, the tab  710  is urged into an interlocking engagement with the slot  708  by a rigid back surface  712  of the chassis  704  when the chassis  704  is inserted into the shell  702 . In order to disengage the chassis  704  from the shell  702 , the rigid back surface  712  may be pressed toward the front of the shoe  700  so that the tab  710  releases from the slot  708  in the shell  702 . The heel portion of the chassis  704  may then be drawn upward and out of the shell  702 , as described above. 
   It will also be noted that a reinforced area  714  is provided on the foot enclosure  706 . This may prevent chaffing when this region of the foot enclosure  706  is aligned with laces  716  of the shell  702 . The reinforced area  714  may be rigid to distribute the pressure exerted by the laces  716  (or other cinching mechanism) against the foot enclosure  706  when the shoe  700  is in use. 
     FIG. 8  is a front side view of subcomponents of a modular shoe. The shoe  800  may be any of the shoes described above, and may include a shell  802 , a chassis  804 , and a foot enclosure  806 . In addition to many of the features described above, this view illustrates the treads  808  and lower surfaces  810  that protrude from the chassis  804  to fill mating openings in a bottom surface of the shell  802 . 
   Other additions and modifications may be made to the modular shoes described herein that are not depicted in the above drawings. For example, an optional or supplemental layer may be provided to be worn under certain weather conditions. This weatherproof layer may present a barrier to, for example, water, snow, or wind, so that a shoe additionally employing the weatherproof layer is specifically adapted for use in water, snow, or mud, or on surfaces such as ice, or in particular inclement conditions. The weatherproof layer may also be designed for other weather conditions, such as by fashioning the layer of an absorbing or wicking material for use in hot weather. The weatherproof layer may be disposed about the outside of the shell to provide an exterior barrier to such elements or conditions, or the weatherproof layer may be disposed between layers of the shoe, such as between the shell and the chassis, or between the chassis and the foot enclosure, or more generally anywhere between the shell and the foot enclosure of the shoes described above. The weatherproof layer may also be a sock, bootie, or similar sheath that serves as a foot enclosure in place of, or in addition to, the foot enclosures described above. 
   In certain embodiments, the components of the shoe may be collapsible to permit convenient stowage, such as in a travel bag or other location where space is limited. Non-rigid components may be collapsible in any convenient fashion. Relatively rigid components may include grooves, creases, or hinges to permit folding along certain lines into a more compact geometry suitable for packing or other stowage. Any one or more of the components may be collapsible in this fashion. 
   In various embodiments, the modular shoe described herein may provide a number of advantages over existing shoes. The modular shoe may be compact and lightweight, while providing the functional and stylistic variety of a number of different shoe types and colors. The relatively low weight and small size, when compared to numerous pairs of shoes that might otherwise be required or desired, may provide particular advantage to a traveler with limited luggage space for footwear. Furthermore, the shoe may be separated into components that may be more easily cleaned and dried, and components such as the foot enclosure or chassis may be refreshed and replaced conveniently to avoid wearing the same footwear over a number of days. 
   In certain embodiments, some or all of the components of the shoe may be washable to permit cleaning of shoes in a sink or, if machine washable, with other laundry. To this end, some or all of the components may be made of washable materials that can be cleansed with water and soap or other detergents or cleaning agents. Such materials may include a washable leather or any of a number of synthetic materials. The material(s) may be hydrophobic to facilitate drying and relatively quick reuse. 
   While the invention has been disclosed in connection with the preferred embodiments shown and described in detail, it will be understood that the invention is not to be limited to the embodiments disclosed herein, but is to be understood from the following claims, which are to be interpreted as broadly as allowed under the law.