Abstract:
The invention relates to an article of footwear having a hollow heel cavity that is adapted to receive a heel insert. A user can interchange heel inserts of varying thicknesses based on their activity, and is not required to change their footwear when undertaking a new activity. For example, hiking on a dirt trail may require a heel insert with less cushioning and more support, while running on pavement may require a heel insert with more cushioning and less support. The user can simply carry with him multiple heel inserts and replace the heel insert as needed to achieve a desired level of support, cushioning and comfort.

Description:
BACKGROUND 
       [0001]    1. Field 
         [0002]    The present invention relates generally to an improved heel for footwear and, more particularly, to a heel insert for footwear that can be replaced to achieve a desired level of support, cushioning, and comfort. 
         [0003]    2. Description of the Related Art 
         [0004]    Footwear, such as sandals and shoes, designed for walking and other forms of exercising typically include a laminated sole attached to a soft and pliable upper. The laminated sole generally includes a resilient rubber outsole attached to a more resilient sole usually made of polyurethane, ethylene vinyl acetate (EVA), or a rubber compound. When laminated, the sole is attached to the upper as a one-piece structure, with the rear sole being integral with the forward sole. 
         [0005]    The heel of the rear sole is generally the first part of footwear to impact the ground. This heel strike, as it is generally known, places extra stress on the heel and can lead to unnecessary repetitive motion injury. Footwear designers have long recognized that shock absorption and diffusion are necessary to reduce the stress on initial impact of the heel. 
         [0006]    One problem associated with traditional footwear is that it provides the same level of heel support and cushioning regardless of the user&#39;s activity. For example, traditional footwear designed for walking or running usually has cushioned and flexible soles to promote a natural gait on hard surfaces such as asphalt or concrete, while hiking footwear usually has stiffer soles to protect against sharp rocks and other objects typically encountered on the trail. However, a user receives the same level of heel support and cushioning if they choose to wear the same article of footwear for both activities. This may not be ideal as the user may receive too little or too much support and cushioning depending on his activity. 
         [0007]    A solution to this problem would be for the user to buy multiple shoes with different levels of heel support and cushioning, and to change the footwear based on the activity they are participating in. This solution, however, can be expensive as it requires the user to purchase multiple shoes for each activity they are participating in. This can be impractical if the user participates in numerous activities that each requires a different level of heel support and cushioning. 
         [0008]    Furthermore, this solution is cumbersome if the user is hiking, for instance, on paths in the woods, then on a road surface, and finally on the beach, all in one outing. Each of these surfaces requires a different level of heel support and cushioning, thus the user would need to carry three different articles of footwear while they are hiking. 
         [0009]    Thus, there is a need for an improved article of footwear that has an adjustable heel support to provide a proper level of support, cushioning and comfort based on the activity the user is participating in. 
       SUMMARY 
       [0010]    In one embodiment, the present invention relates to an article of footwear comprising: a sole having a smooth top surface adapted for placement of a user&#39;s foot and a treaded bottom surface adapted for placement on a ground surface; a securing device on the top surface of the sole and adapted to receive the user&#39;s foot; a heel portion defining a hollow cavity positioned at the rear portion of the bottom surface of the sole, the heel portion having an upper surface, a lower surface, and two flexible side walls, and the heel portion having an open front portion and a closed rear portion; a plurality of connectors positioned on each side wall connecting the upper surface of the heel portion and the lower surface of the heel portion, the plurality of connectors spaced apart by openings in each side wall; a recessed portion defining a gripping area for fingers positioned at the front portion of the lower surface of the heel portion; and a removable insert placed inside the hollow cavity through the front portion to adjust the level of support provided to the heel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    These and other embodiments of the present invention will be discussed with reference to the following non-limiting and exemplary illustrations, in which like elements are numbered similarly, and where: 
           [0012]      FIG. 1  is a top view of a sandal in accordance with an embodiment of the present invention; 
           [0013]      FIG. 2  is a perspective view of a bottom portion of the sandal of  FIG. 1  in accordance with an embodiment of the present invention; 
           [0014]      FIG. 3  is a bottom view of the sandal of  FIG. 1  in accordance with an embodiment of the present invention; 
           [0015]      FIG. 4  is a side view of the sandal of  FIG. 1  without a heel insert placed inside a heel portion of the sandal in accordance with an embodiment of the present invention; 
           [0016]      FIG. 5  is a side view of the sandal of  FIG. 1  with the heel insert placed inside the rear portion of the sandal in accordance with an embodiment of the present invention; 
           [0017]      FIG. 6  is a top view of a heel insert in accordance with an embodiment of the present invention; 
           [0018]      FIG. 7  is a perspective view of the heel insert of  FIG. 6  in accordance with an embodiment of the present invention; 
           [0019]      FIG. 8  is a side view of the heel insert of  FIG. 6  in accordance with an embodiment of the present invention; and 
           [0020]      FIG. 9  is a bottom view of the heel portion of the sandal of  FIG. 1  with the heel insert placed inside the heel cavity of the sandal in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]      FIG. 1  is a top view of a sandal  1  in accordance with an embodiment of the present invention. Upper surface  2  of sandal  1  is generally composed of rubber, polyurethane, foamed ethylene vinyl acetate (EVA), butadiene, styrene butadiene, isoprene, or any material with comparatively good flexibility. Upper surface  2  is preferably contoured in a concave manner to accommodate the underside of wearer&#39;s foot, and in particular, to provide support and comfort. 
         [0022]    Sandal  1  comprises securing device  3  to secure a user&#39;s foot at a position where a gap exists between the big toe and the adjacent toe when the foot is placed on upper surface  2 . Securing device  3  may be a strap having strap ends  4  and  5  and tab  6 . Tab  6  is fixed to upper surface  2  preferably by a rivet. Strap ends  4  and  5  may be connected to opposite longitudinal sides of upper surface  2  preferably by thermo-compression bonding. However, any suitable means of fastening both tab  6  and strap ends  4  and  5  to upper surface  2  may be utilized. In one embodiment of the present invention, securing device  3  may be laces, a thong strap, a closed-toe covering or any other means to hold the user&#39;s foot securely to the sole of the article of footwear. 
         [0023]      FIG. 2  is a perspective view of a bottom portion (i.e., a sole) of the sandal  1  of  FIG. 1  in accordance with an embodiment of the present invention. Sole  7  of sandal  1  is generally composed of rubber, polyurethane, foamed EVA, butadiene, styrene butadiene, isoprene, or any material with comparatively good flexibility. Sole  7  preferably comprises traction grooves  9  and channels  10  to improve traction and prevent slippage when sole  7  is placed on a ground surface. 
         [0024]    Sole  7  includes front surface  8  and heel surface  11 . Underneath the heel surface  11  is a hollow heel cavity  12 . Heel cavity  12  is adapted to receive a heel insert that allow the user to adjust the level of support and cushioning that is provided to heel surface  11 . Heel surface  11  is preferably flexible and expandable to allow for various sized heel inserts to be placed in heel cavity  12 . Heel surface  11  comprises a recessed center portion  14  to facilitate insertion and removal of heel inserts. Heel cavity  12  has an open front portion  13  where heel inserts can be placed inside heel cavity  12  and a closed rear portion  15  to secure heel inserts within heel cavity  12 . 
         [0025]      FIG. 3  is a bottom view of the sandal  1  of  FIG. 1  in accordance with an embodiment of the present invention.  FIG. 3  depicts heel insert  16  positioned inside heel cavity  12 . Heel insert  16  can be slidably inserted into heel cavity  12  through open front portion  13 , and is secured within heel cavity  12  upon contact with closed rear portion  15 . Heel inserts of various sizes, thicknesses and rigidities can be placed inside heel cavity  12  depending on the user&#39;s desired level of support, cushioning and comfort. For example, a user that weighs over 200 pounds may want a more rigid heel insert than a user that weighs 100 pounds. 
         [0026]      FIG. 4  is a side view of the sandal  1  of  FIG. 1  without a heel insert placed inside a heel portion of the sandal in accordance with an embodiment of the present invention. Heel cavity  12  is defined by side wall  17 , open front portion  13 , closed rear portion  15 , heel surface  11  on the bottom, and rear portion  22  of upper surface  2  on the top. Side wall  17  is further defined by connectors  18  and  19  which are spaced apart by openings  20  and  21  along the perimeter of side wall  17 . Connectors  18  and  19  are preferably flexible to allow heel cavity  12  to expand to accommodate heel inserts of various sizes. Both sides of the sandal  1  may have connectors  18  and  19  which are spaced apart by openings  20  and  21 . 
         [0027]      FIG. 5  is a side view of the sandal  1  of  FIG. 1  with the heel insert  16  placed inside the rear portion  22  of the sandal  1  in accordance with an embodiment of the present invention. Heel insert  16  is slidably inserted into heel cavity  12  through open front portion  13  until heel insert  16  comes into contact with closed rear portion  15 . Heel insert  16  can be seen inside heel cavity  12  through openings  20  and  21  in side wall  17 . Heel insert  16  is not permanently affixed to heel surface  11  or inside heel cavity  12 , but rather temporarily secured within heel cavity  12  and easily removable and interchangeable with another heel insert. 
         [0028]      FIG. 6  is a top view of a heel insert  16  in accordance with an embodiment of the present invention. Heel insert  16  preferably generally has the same shape as heel surface  11 , so that the entire heel area of sandal  1  is supported by heel insert  16 . Heel insert  16  preferably comprises a substantially flat front surface  24  and a semicircular rear surface  25 . A concave recessed groove  26  is positioned at front surface  24 , and includes gripping means  27 . Gripping means  27  may be raised ridges, indentations, grooves, or any other means which improve the user&#39;s finger grip of recessed groove  27 . Recessed groove  26  is used to assist the user in inserting and removing heel insert  16  to and from heel cavity  12 . 
         [0029]    In the preferred embodiment, heel insert  16  is fabricated from a lightweight rigid material, such as rubber, in order to minimize the weight of sandal  1 . Preferably, heel insert  16  is a single piece of molded, durable and hard wearing elastomeric material such as rubber or rubber composition material, although it will be apparent that various other materials of a semi-elastomeric or even slightly rigid material, including various plastic, foam, foam composites, or resinous substances, polymeric materials, and the like, including leather, composite leather, or wood may be employed. However, a somewhat elastomeric and at least partly flexible material is preferred in order to impart to the shoe a flexible, comfortable nature while the user is walking. In one embodiment, heel insert  16  may be an air bag filled with air. The amount of air in the air bag can be adjusted for improved support and comfort. 
         [0030]    Heel insert  16  can be color coded to correspond to a particular activity. For example, a red insert may correspond to a high level of support and less cushioning, while a yellow insert may correspond to a high level of cushioning and less support. A green heel insert  16  may be used for leisure activities. The user can easily determine the appropriate heel insert to use for an activity based on the color. In one embodiment, a first insert may have a hardness of between about 20 and 30 Asker C, a second insert may have a hardness of between about 30 and 40 Asker C, and a third insert may have a hardness of between about 40 and 50 Asker C. 
         [0031]      FIG. 7  is a perspective view of heel insert  16  of  FIG. 6  in accordance with an embodiment of the present invention. Recessed groove  26  is preferably indented in a concave manner to accommodate the user&#39;s finger. Gripping means  27  is positioned along the entire surface of recessed groove  26  to provide a sufficient grip for the user&#39;s finger. A convex side of recessed groove  26  (not shown) is shaped in a convex manner corresponding to the concave surface of recessed groove  26 . The convex side may also contain gripping means. The convex side may be positioned below the concave side when heel insert  16  is positioned inside heel cavity  12 . Recessed center portion  14  allows recessed groove  26  (see also  FIG. 3 ) to be exposed so the user&#39;s fingers can easily insert and remove heel insert  16 . 
         [0032]      FIG. 8  is a side view of the heel insert of  FIG. 6  in accordance with an embodiment of the present invention. Thickness T is the height of heel insert  16 . Heel insert  16  is removable from heel cavity  12 , allowing the user to replace a heel insert with other heel inserts of varying thicknesses, each thickness corresponding to a different level of support, cushioning and comfort. 
         [0033]      FIG. 9  is a bottom view of the heel portion of the sandal of  FIG. 1  with the heel insert  16  placed inside the heel cavity  12  of the sandal  1  in accordance with an embodiment of the present invention. Heel insert  16  is placed within heel cavity  12  through open front portion  13 . Heel surface  11  comprises a recessed portion  14  shaped to accommodate convex portion  28  of heel insert  16 . 
         [0034]    The invention is not limited to sandals and open-toe footwear, and can be employed on various articles of footwear such as shoes, boots, slippers, and other closed-toe articles of footwear. 
         [0035]    While the specification has been disclosed in relation to the exemplary and non-limiting embodiments provided herein, it is noted that the inventive principles are not limited to these embodiments and include other permutations and deviations without departing from the spirit of the present invention.