1. Field
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.
2. Description of the Related Art
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.
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.
One problem associated with traditional footwear is that it provides the same level of heel support and cushioning regardless of the user'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.
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.
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.
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.
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'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'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.
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:
Sandal 1 comprises securing device 3 to secure a user'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's foot securely to the sole of the article of footwear.
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.
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.
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.
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.
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.