Cushioning sole for an article of footwear

Disclosed herein is a shoe construction for providing increased cushioning effects. The shoe includes a sole, a footbed, and a layer of a plurality of deformable protrusions disposed between at least a portion of the sole and the footbed, particularly in the heel and the forefoot area of the shoe. Each of the protrusions includes a tip facing and freely movable with respect to a lower surface of the footbed. Each of the protrusions also includes a base fixedly attached to the sole so that the base does not move relative to said sole. The protrusions provide cushioning by bending when a foot presses down upon them. An alternate embodiment shows the cushioning sole adapted for use in a sandal.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the construction of an article of footwear and more specifically to a cushioning construction for the sole of an article of footwear.

2. Background of the Invention

The human foot is a complex and remarkable piece of machinery, capable of withstanding and dissipating many impact forces. The natural padding of fat at the heel, as well as the collapsibility of the arch, help to cushion the foot. Throughout the course of an average day, the feet and legs of an individual are subjected to substantial impact forces. Running, jumping, walking, and even standing exert forces upon the feet and legs of an individual which can lead to soreness, fatigue, and injury.

Although the human foot possesses natural cushioning and rebounding characteristics, the foot may need extra support to overcome many of the forces encountered during extended periods of activity. Unless an individual is wearing shoes which provide proper cushioning and support, the soreness and fatigue resulting from even low levels of activity on unnatural surfaces is acute, and its onset accelerated. The discomfort for the wearer that results may diminish the incentive for further activity. Equally important, inadequately cushioned footwear can lead to injuries such as blisters; muscle, tendon and ligament damage; and bone stress fractures. Improper footwear can also lead to other ailments, including back pain.

In light of these problems, numerous attempts have been made to incorporate into the sole of a shoe improved cushioning and resiliency. For example, attempts have been made to enhance the natural elasticity and energy return of the foot by providing shoes with soles which store energy during compression and return energy during expansion. These attempts have included the formation of shoe soles that include springs, gels or foams. However, these solutions are expensive, and tend to lose their effectiveness over time.

SUMMARY OF THE INVENTION

Accordingly, disclosed herein is a shoe construction for providing increased cushioning effects. The shoe includes a sole, a footbed, and a layer of a plurality of deformable protrusions disposed between at least a portion of the sole and the footbed, particularly in the heel and the forefoot area of the shoe. Each of the protrusions includes a tip facing and freely movable with respect to a lower surface of the footbed. Each of the protrusions also includes a base fixedly attached to the sole so that the base does not move relative to said sole. The protrusions provide cushioning by bending when a foot presses down upon them.

DETAILED DESCRIPTION OF THE INVENTION

Specific embodiments of the present invention are now described with reference to the figures, where like reference numbers indicate identical or functionally similar elements.

Referring now toFIG. 1, a shoe100according to the present invention is shown in cross-section, the section taken lengthwise (from toe to heel) at the center of shoe100. A left foot shoe is shown, but it will be apparent to one of ordinary skill in the art that a right foot shoe is merely a mirror image thereof.

Shoe100generally includes three basic components, an upper102, a sole103, and a footbed110. Upper102can be of any material or design known to one of ordinary skill in the art. Common materials used for upper102include leather, woven materials such as canvas, and synthetic materials such as vinyl.

In one embodiment sole103includes an outsole104, a midsole106, and a plurality of protrusions108. Outsole104is constructed of a resilient, durable material such as rubber. Outsole104is intended to provide traction as the ground-engaging surface of shoe100. In the embodiment shown inFIG. 1, outsole104covers the entire lower-most surface of sole103. It will be apparent to one skilled in the art that outsole104may cover only portions of sole103, or could be eliminated entirely.

As shown inFIG. 1, midsole106is disposed between outsole104and footbed110. Midsole106provides structure to sole103, as well as additional padding between a wearer's foot and the ground. However, midsole106is generally constructed of a material that is less dense than that used for outsole104, so that the thickness of sole103may be increased, while keeping down the weight of shoe100. Examples of materials appropriate for midsole106include rubber, ethyl vinyl acetate (EVA), polyurethane (PU), and thermoplastic urethane (TPU).

In one embodiment midsole106is disposed along the entire length of sole103. In one embodiment midsole106is shaped to include depressions in the heel section and the forefoot section of sole103, as shown inFIGS. 1 and 2. These depressions create space for the insertion of cushioning protrusions108so as to minimize the thickness and bulk of sole103. It will be apparent to one of ordinary skill in the art that these depressions may be altered in length, such as to extend the full length of sole103, depth, and shape, or even eliminated entirely.

Cushioning protrusions108are disposed between midsole106and footbed110. Protrusions108may be disposed in the heel region of sole103, the forefoot region of sole103, along the entire length and width of sole103, or a combination of these configurations. In the embodiment shown inFIG. 1, with protrusions108located in a heel region and forefoot region of sole103, with no protrusions108in an arch region of sole103. Instead, an insole layer105is stretched across the width of sole103in the arch region to increase the stability of shoe100. The placement of protrusions108will depend upon the desired location of cushioning.

Referring now toFIG. 2, protrusions108are shown in cross-section taken along line2—2in FIG.1. As can be seen clearly inFIG. 2, each protrusion108includes a tip212and a base214. In one embodiment, a vertical axis216of protrusions108passing through tip212is set at a right angle to base214, i.e., protrusions108do not slant towards either a toe region or a heel region of shoe100. Although other alignments of protrusions108are possible, this alignment of protrusions108facilitates the proper bending thereof.

Tip212touches but is moveable with respect to a lower surface of footbed110. In the embodiment shown inFIG. 2, base214is fixedly attached to midsole106. In this embodiment, protrusions108are formed on a sheet, so that the sheet may be trimmed to an appropriate size to be inserted into the depressions created in midsole106. However, protrusions108could also be individually formed and attached directly to midsole106, although this process would be very labor intensive and achieving a uniform layer of protrusions could be difficult without skilled technicians. In either case, base214of protrusion108is attached to midsole106, either directly or indirectly as part of the sheet, so that base214does not move with respect to midsole106. In one embodiment, base214is permanently affixed, such as by cement, although base214may alternatively be more temporarily affixed, such as by a temporary adhesive or by hook and loop fasteners such as Velcro®. Such a temporary attachment would allow for custom designs for changing the hardness of protrusions108upon demand or to allow for easy replacement of protrusions108.

In addition to attaching protrusions108to an upper surface of midsole106, protrusions108may be molded as an integrated part of midsole106, as shown in FIG.5. In another embodiment, shown inFIG. 6, protrusions108are attached to or integrally molded with outsole104so that tips212face or even touch footbed110. Midsole106may still be used in this embodiment, where protrusions108would project through coordinating windows or holes cut into midsole106to touch a lower surface of footbed110.

Protrusions108are formed of a softer material than that of midsole106, as the cushioning is a result of the ability of protrusions108to bend and deform in response to the application of a downward force, such as a step, as will be described in greater detail herein. Appropriate materials are similar to those mentioned above with respect to midsole106, such as rubber, EVA, thermoplastic rubber (TPR), silicone, thermoplastic elastomers such as SEBS, and urethane, although the density of the materials must be chosen to allow for the cushioning effect from the bending of protrusions108. If the material is too hard, then protrusions108will not bend to a sufficient degree to cushion; if the material is too soft, then protrusions108will spread outwardly or crush (as opposed to bending), and the material will wear too quickly. In one embodiment, the durometer for the material in the present invention is in the range of 45-75 on the Asker C scale. However, if protrusions108are situated closer to the foot, e.g., if a thin footbed is used, then the material will be softer, so that the bottom of the foot is not irritated.

In one embodiment, protrusions108are conical in shape, with tip212(i.e., the apex of the cone) facing the bottom surface of footbed110. Other shapes for protrusions108are also possible.

Referring again toFIG. 1, the height of protrusions108must be sufficient to allow for bending. For the example durometer range noted above (45-75 on the Asker C scale) of the material, a range of the height of protrusions108is between 5 mm to 9 mm. Shorter than 5 mm and protrusions108may not bend. Greater than 9 mm and sole103becomes prohibitively bulky. However, it will be apparent to those skilled in the art that heights outside of this range are acceptable, such as if a shoe with a platform or otherwise thick sole is being designed or if materials outside of the noted durometer range are used.

The width of protrusions108will vary with the height, so that appropriate bending may occur. For the embodiment described above using cone-shaped protrusions, a range of appropriate diameters of base214is from approximately 3 mm to 6 mm. Again, this dimension will vary widely, depending upon the shape of protrusions108, the material used, and the desired amount of bending.

The number and arrangement of protrusions108will vary depending upon the dimensions thereof and the level of desired cushioning. Protrusions108must be spaced far enough apart so that the bending of protrusions108is not inhibited. For the purposes of example only, in one embodiment protrusions108are arranged in symmetrical rows. If each conical protrusion108is approximately 6 mm high and the diameter of base214is approximately 4 mm wide, then the concentration of protrusions108is slightly greater than one per centimeter.

Footbed110is disposed above protrusions108. Footbed110reduces the tactile sensation of tips212of protrusions108on the wearer's foot. In one embodiment, footbed110includes several layers. In one embodiment, main layer107is made of a resilient material, such as PU, with a felt or other soft material as the uppermost layer109. The heel of footbed110may include a heel cup111made of a harder, more rigid material to provide additional reduction of the point sensation caused by the tips212of protrusions108. Such materials include plastic, rubber, non-woven synthetic or natural materials or a tightly woven or knitted material.

In one embodiment, footbed110is removable, i.e., footbed110is not fixedly attached to shoe100or sole103at any point, but it is merely inserted into shoe100and held in place by frictional forces. Alternatively, footbed110may be attached to shoe100or sole103along the periphery thereof, such as by cementing or stitching. However, tips212of protrusions108should still be freely movable with respect to footbed110.

The cushioning mechanism of protrusions108will now be described with reference to FIG.2. As a wearer steps down, pressure is applied to footbed110. Footbed110translates this force to protrusions108, in particular, those protrusions108in the vicinity of the force. As tips212of protrusions108are not attached to footbed110, protrusions108are free to bend and deform to cushion the step. Footbed110is sufficiently thick and the bottom material is sufficiently stiff to reduce or eliminate the irritating tactile sensation of tips212on the sole of the wearer's foot. However, a massaging sensation due to the movement of protrusions108beneath footbed110may remain.

Referring now toFIG. 3, an alternate embodiment of the present invention is shown.FIG. 3shows a lengthwise cross-sectional view of a sandal300including the cushioning sole of the present invention. The construction of sandal300is slightly different from that of shoe100(as shown in FIG.1).

Sandal300includes an upper302and a sole303. As is readily apparent to one of ordinary skill in the art, upper302is similar to upper102in the embodiment discussed above with respect toFIG. 1, although with a relatively open design.

Sole303includes one or several layers. In one embodiment with multiple layers, as is shown inFIG. 3, an outsole304is a relatively thick layer made of a resilient material such as rubberized or durable EVA. Outsole304provides most of the thickness of sole303. An insole board306is typically a non-woven material disposed between hard outsole304to cushioning protrusions308, such as PU or EVA. Insole board306helps to control excessive motion of the foot for greater stability. For additional stiffness and stability, sole303may also include in the heel and arch regions a rigid plate (not shown) made of a material such as plastic or metal.

It will be apparent to one of ordinary skill in the art that insole board306may be eliminated altogether. For such a sole design with only one layer, sole303is made of a resilient but lightweight material, such as rubberized EVA, PU, or blown rubber.

Protrusions308are similar to protrusions108, described above with respect to the embodiment shown inFIG. 1, in that protrusions308may be disposed in the heel region of sole303, the forefoot region of sole303, along the entire length and width of sole303, or a combination of these configurations. In the embodiment shown inFIG. 3, protrusions308are located along the entire length (and width, not shown) of sole303.

As may be with protrusions108, in one embodiment protrusions308are formed as a sheet, so that the sheet may be cemented to insole board306. Protrusions308are formed of the same materials as described above with respect to protrusions108, namely rubber, EVA, and urethane, with a hardness in one embodiment in the range of 45-75 on the Asker C scale. Also similar to protrusions108, protrusions308are in one embodiment conical in shape, with a height in a range of 5 mm to 9 mm. All of the variations discussed above with respect to protrusions108apply equally to protrusions308, such as molding protrusions308integrally with sole303or insole board306or altering the shape of protrusions308.

Finally, a wrapping310is attached to outsole304around the periphery thereof. Wrapping310completely covers protrusions308and insole board306. Wrapping310provides many of the same features as footbed110, described above with respect to FIG.1. Wrapping310adds an aesthetic and tactile effect, as in a sandal wrapping310is more visible than a footbed would be in a closed shoe. Wrapping310is in one embodiment made of a non-woven material, such as leather, to provide the same force transfer and tactile-sensation reduction as provided by footbed110. Also, in one embodiment, a separate layer of material is affixed to wrapping310to reduce further the tactile sensation of protrusions310on the wearer's foot. The attachment of wrapping310to outsole304can be of any method known in the art, such as by stitching or cementing.

The cushioning mechanism of protrusions308is the same as that described above with respect to protrusions108in the embodiment shown in FIG.2.

Referring now toFIG. 4, a further alternate embodiment of the present invention is shown. A shoe400includes an upper402, a sole403, and a footbed410. Upper402is comparable in form, structure, and materials with upper102, described with respect to FIG.1. Similarly, footbed410is comparable to footbed110, described above with respect to FIG.1.

In one embodiment sole403includes an outsole404, a midsole406, and a plurality of protrusions or ridges408. Outsole404is constructed of a resilient, durable material such as rubber. Outsole404is intended to provide traction as the ground-engaging surface of shoe400. In the embodiment shown inFIG. 4, outsole404covers the entire lower-most surface of sole403. It will be apparent to one skilled in the art that outsole404may cover only portions of sole403, or could be eliminated entirely.

As shown inFIG. 4, midsole406is disposed between outsole404and footbed410. Midsole406is similar in form and function to midsole106, described above with respect to FIG.1. Examples of materials appropriate for midsole406include rubber, ethyl vinyl acetate (EVA), polyurethane (PU), and thermoplastic urethane (TPU).

In the embodiment shown inFIG. 4midsole406is disposed along the entire length of sole403. In this embodiment, midsole406is shaped to include depressions in the heel section and the forefoot section of sole403. These depressions create space for the insertion of ridges408so as to minimize the thickness and bulk of sole403. It will be apparent to one of ordinary skill in the art that these depressions may be altered in length, such as to extend the full length of sole403, depth, and shape, or even eliminated entirely.

Ridges408are fin-like protrusions extending transversely across shoe400. Ridges408bend in response to pressure from a wearer's foot to cushion the step, much like the bending of protrusions108, described above. Ridges408could be straight, wavy, curved, set at acute or oblique angles to a longitudinal axis of shoe400, or any combination of these features. As with protrusions108, ridges408are attached directly to midsole406or are formed as a sheet which is attached to midsole406. In another embodiment where midsole406is eliminated from the design, ridges408are attached to outsole404. The attachment of ridges408is by any of the methods described above with respect to protrusions108, such as by cementing or co-molding.

In cross-section, ridges408have a tip412, which is freely movable with respect to footbed410, extending to a base414, which is fixedly attached to a midsole406. In one embodiment, a vertical axis416of ridges408passing through tip412is set at a right angle to base414, i.e., ridges408do not slant towards either a toe region or a heel region of shoe400. Although other alignments of ridges408are possible, this alignment of ridges408facilitates the proper bending thereof.

The height and width of ridges408is comparable to those of protrusions108. Ridges408, however, extend nearly the entire width of shoe400. Arranged in rows, the concentration of ridges408is similar to that of protrusions108, slightly more than one per centimeter. The materials used for ridges408are similar to those used for protrusions108, namely such as rubber, EVA, thermoplastic rubber (TPR), silicone, thermoplastic elastomers such as SEBS, and urethane. The hardness of these materials is also comparable to that of the materials used in protrusions108, having a durometer in the range of 45-75 on the Asker C scale. As with protrusions108, this range will depend upon the dimensions of ridges408as well as the placement of ridges408in relation to the wearer's foot, e.g., a thinner footbed410requires a softer material for ridges408.

It will be appreciated by those skilled in the art that the features of the invention may be altered to tailor the characteristics of shoe100, sandal300, or shoe400. For example, the layers of sole103, sole303, or sole403(e.g., outsole104, midsole106, and projections108) may be made of a variety of materials, including but not limited to plastic, foam, and rubber. The various layers may be secured to each other using any one of the many well known methods in the art, such as cementing, welding, or stitching.

Construction of the various layers of sole103, sole303, or sole403may be accomplished by any one of the many methods known in the art. For instance, the layers may be formed by injection molding, compression molding, or other suitable methods. Also, it is contemplated that the different layers of sole103, sole303, or sole403described herein can be replaced by one single layer of material, in which the density, flexibility, and pliability may differ throughout the material, or a single material may be used.

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. All patents and publications discussed herein are incorporated in their entirety by reference thereto.