The present invention relates to footwear and more particularly to an article of footwear with a heel support assembly.
Conventional footwear typically includes two primary elements: an upper and a sole. The upper can be formed of a lightweight and flexible material, for example leather or synthetic materials, and can provide ventilation to the wearer's foot. The sole can include multiple layers, for example an insole, a midsole, and an outsole. The insole is sometimes positioned within the upper to provide added comfort to the wearer's sole. The midsole is generally joined to the upper and provides energy absorption, often in the heel strike area. The outsole is generally formed from a wear resistant material and includes tread elements to provide the desired degree of traction for the intended application of the article of footwear.
Heel support is an important aspect in the design and construction of modern footwear. Insufficient heel support along the upper is known to lead to injuries to the heel and over pronation of the wearer's foot. Heel counters are well known in athletic and other types of footwear, and are typically constructed to provide heel support to an otherwise lightweight and flexible upper. Known heel counters include a curved plastic insert that extends around the heel bone (calcaneus) to cradle each side of the wearer's foot. However, the support provided by heel counters typically comes at a cost, namely discomfort in the heel over extended wear and the lack of a customized fit for differently shaped heels.
Accordingly, there remains a continued need to provide improved heel support for an article of footwear. In particular, there remains a continued need for an article of footwear having a lightweight system of heel support that provides comfort and stability for a range of differently shaped feet.
The present invention provides an article of footwear having a heel support assembly with a memory foam layer situated internally of a heel counter. The heel memory foam layer may have a thickness that is sufficient to embrace the heel of the wearer's foot, potentially cradling the calcaneus, the retrocalcaneal bursa and the base of the Achilles tendon. The heel support assembly may also include a heel cradle extending around an external portion of the upper and including a lasting allowance. The heel cradle may provide torsional support in the arch region (or waist) of the article of footwear, for example when the heel support assembly is incorporated into an article of footwear with a strobel construction.
In one embodiment, the heel memory foam layer is somewhat dome-shaped having a maximum thickness through a center region and tapering gradually thinner toward its peripheral edge. For example, the heel memory foam layer may have a maximum thickness of approximately 10 mm. The maximum thickness may, however, vary from application to application, for example, in the range of about 7 mm to about 30 mm. The heel memory foam layer may be molded and, after molding, laminated to a plastic heel counter. Alternatively, the heel memory foam layer may be molded directly onto the heel counter. For example, the heel counter may be placed within the heel memory foam layer mold prior to molding of the heel memory foam layer so that they become intimately attached as the heel memory foam cures.
In one embodiment, the upper also includes a transitional foam layer integrated into the upper above the heel counter. The transitional foam layer may be situated immediately above the heel memory foam layer to provide a smooth transition along the inside of article of footwear. The thickness of the transitional foam layer may be substantially smaller than the thickness of the heel memory foam layer. For example, the transitional memory foam layer may be approximately 3 mm in thickness. This thickness is merely exemplary and the thickness may be in the range of about 1 mm to about 20 mm.
In one embodiment, the heel support assembly includes an overlay situated over the upper in a region generally corresponding to the heel counter. The overlay may be substantially coextensive with the heel counter. However, it may have a different size and/or shape than the heel counter. For example, the overlay may be somewhat smaller or somewhat larger than the heel counter.
In one embodiment, the article of footwear has a strobel construction in which the upper is closed by a strobel board. The strobel construction may include a generally flexible strobel board that is joined to the lasting margin of the upper by a butt-seam. The strobel construction may provide an athletic-inspired, low-weight article of footwear.
In one embodiment, the heel cradle is disposed at the bottom of the upper around the heel region. The heel cradle provides additional support to the heel to help keep the foot in place. The heel cradle may be manufactured from a relatively rigid and resilient material, such as thermoplastic polyurethane. The cradle may extend forwardly to provide additional torsional control. This additional torsional control may be particularly beneficial when incorporated into footwear with more flexible constructions, such as a strobel construction. The cradle may include a lasting allowance that extends under the upper and is secured to the sole. The lasting allowance may be provided only in the arch region (or waist) of the article of footwear.
The heel cradle may have a shorter section in the rear of the heel. The shorter section may provide improved comfort in some applications by allowing some degree of flexibility in the portion of the heel overlying the retrocalcaneal bursa.
In one embodiment, the article of footwear includes an insole specifically configured to interact with the heel support assembly. In this embodiment, the insole may be manufactured from a material that is highly resistant to compression set. For example, the insole may be manufactured from cast-mold polyurethane having a compression set of ≤5% after 500,000 compressions and a recovery period of 24 hours.
The present invention provides an article of footwear with a heel support assembly that simultaneously provides improved comfort and improved support for the heel. The heel memory foam helps to firmly, yet comfortably, lock the wearer's foot into the article of footwear. The various components of the assembly are configured to collectively provide a unique degree of customized fit without compromising support. The heel memory foam layer is intended to conform to the wearer's foot in and around the rear and sides of the heel. The cradle may be provided to give torsional support in the arch region (or waist) of the article of footwear—particularly when the heel support assembly is incorporated into an article of footwear with a strobel construction.
These and other objects, advantages, and features of the invention will be more fully understood and appreciated by reference to the description of the current embodiment and the drawings.
Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited to the details of operation or to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention may be implemented in various other embodiments and of being practiced or being carried out in alternative ways not expressly disclosed herein. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. Further, enumeration may be used in the description of various embodiments. Unless otherwise expressly stated, the use of enumeration should not be construed as limiting the invention to any specific order or number of components. Nor should the use of enumeration be construed as excluding from the scope of the invention any additional steps or components that might be combined with or into the enumerated steps or components. Any reference to claim elements as “at least one of X, Y and Z” is meant to include any one of X, Y or Z individually, and any combination of X, Y and Z, for example, X, Y, Z; X, Y; X, Z; and Y, Z.
Referring now to
Referring again to
The upper 12 may include various trim, cushioning and reinforcing elements. For example, a toe cap (not shown) may be provided to reinforce the vamp 16. Further, padding may be sandwiched between the layers of the upper 12, such as between the vamp 16 and an internal liner 24. Reinforcing elements may be affixed to the upper 12 to reinforce the portions of the upper 12 that receive the laces. The interior of the upper 12, such as the vamp 16, tongue 18, and quarters 20, may be covered by the liner 24, for example a layer of DriLex, Cambrelle or other lining materials. The liner 24 may be a single layer of material or it may be a combination of materials. For example, the liner 24 may include integrated padding throughout or in select regions, such as around the ankle and the foot opening. The construction of the illustrated upper 12 is merely exemplary, and the present invention may be incorporated into footwear that includes essentially any upper construction.
As noted above and shown in
Referring now to
The heel counter 34 of the heel counter assembly 38 is shaped to conform to the heel of the article of footwear 10 and provide rigid support to an otherwise flexible upper 12. As perhaps best shown in
The memory foam layer 36 of the heel counter assembly 38 is adapted to provide enhanced comfort for the rear and side portions of the wearer's heel. As used herein, a “memory foam layer” means a slow recovery foam element having a two-dimensional or three-dimensional shape such that, when pressure is applied and released, the slow recovery foam element returns to substantially its original shape. The memory foam layer can include viscoelastic polyurethane foam and low-resilience polyurethane foam for example. The memory foam layer 36 is formed as a sheet-like element in some embodiments, while in the illustrated embodiment the memory foam layer 36 can be formed with a three-dimensional shape. For example, a flat or tapered-flat memory foam layer 36 can applied to the interior of the heel counter 34, such that the memory foam layer 36 assumes a convex curvature and is coextensive with the concave inner surface 48 of the heel counter sidewall 42. In other embodiments a pre-shaped memory foam layer 36 is applied to the interior of the heel counter 34, being pre-shaped with a convex surface that is coextensive with the concave inner surface 48 of the heel counter sidewall 42. The memory foam layer 36 is laminated to the concave inner surface 48 of the heel counter sidewall 42 by adhesive in some embodiments, while in other embodiments the memory foam layer 36 is molded directly to the concave inner surface 48 of the heel counter 34 so that they become intimately attached as the memory foam cures.
The thickness of the memory foam layer 36 can be selected to provide optimized support to the rear and side portions of the wearer's heel. As used herein, the “thickness” of the memory foam layer 36 includes the distance between substantially opposing major surfaces of the memory foam layer 36. The memory foam layer 36 may have a maximum thickness that is sufficient to embrace the heel of the wearer's foot potentially cradling the calcaneus, the retrocalcaneal bursa and the base of the Achilles tendon. For example, the memory foam layer 36 may have a maximum thickness of approximately 10 mm. The maximum thickness may, however, vary from application to application, for example, in the range of about 7 mm to about 30 mm. In addition, the memory foam layer 36 can maintain a substantially constant thickness along its height in some embodiments. For example, the thickness at the rearward-most portion of the memory foam layer 36 (in the heel-toe direction) can be relatively constant. More particularly, the thickness can be least 7 mm, further optionally about 10 mm. In other embodiments, the memory foam layer 36 includes a thickness that varies along its height. For example, and as shown in
As noted above, the memory foam layer 36 is situated internally of the heel counter 34 closest to the wearer's heel to form the heel counter assembly 38. The periphery of the memory foam layer 36 can be shaped according to the intended embodiment. In one embodiment, the heel memory foam layer is somewhat dome-shaped having maximum thickness through a center region and tapering gradually thinner toward its peripheral edge. In another embodiment, the memory foam layer 36 can include a rearwardly-chamfered or rearwardly-beveled upper portion 52 that generally follows the contour of the heel counter upper edge 44. In still other embodiments, the memory foam layer 36 can include a flat upper portion 52 that generally follows the contour of the heel counter upper edge 44 and a flat bottom edge 54 that straddles the wearer's heel. The heel counter assembly 38 is positioned between the upper 12 and the liner 24 in the present embodiment, but can be positioned to directly engage the wearer's foot in other embodiments.
The heel cradle 40 is shaped to provide external heel support to the upper while also aiding in the removal of the article of footwear 10. As perhaps best shown in
The heel support assembly 32 is described above as including a heel counter assembly 38 (heel counter 34 and memory foam layer 36) and a heel cradle 40, but can include greater or fewer elements that provide support to the heel area of the upper 12. For example, the heel support assembly 32 can include only the heel counter assembly 38 in some embodiments. In other embodiments, the heel support assembly 32 can include an overlay 66 that extends around the sides and back of the heel portion of the upper 12, being layered between the upper 12 and the heel cradle 40. This overlay 66 is generally depicted in
Referring again to
The article of footwear 10 can also include an insole 70 specifically configured to interact with the heel support assembly 32. The insole 70 can be manufactured from a material that is highly resistant to compression set. For example, the insole 70 can be manufactured from a material having a compression set of ≤5% after 500,000 compressions and a recovery period of 24 hours. Example insole materials include cast-mold polyurethane, pour molded polyurethane, and expanded thermoplastic polyurethane, available under the name Infinergy from BASF.
To reiterate, the article of footwear 10 of the current embodiment includes a heel support assembly 34 with a memory foam layer 36 incorporated into the heel counter 34. The memory foam layer 36 may be laminated to the interior of the heel counter 34 and may have a thickness in the range of 7 mm to 30 mm. The upper 12 may include a transitional foam layer 68 that is disposed above the heel counter 34 to assist in fitting a wearer's foot into the interior of the article of footwear 10. The transitional foam layer 68 may be configured to provide a gradual entry into the memory foam 36 of the heel counter 34. The transitional foam layer 68 may be tapered to increase in thickness as it approaches the heel counter 34, generally shown in
An article of footwear incorporating a heel support assembly in accordance with a current embodiment can be formed according to the following steps, discussed individually below: a) joining a memory foam layer to a heel counter to form a heel counter assembly; b) securing the heel counter assembly to a heel portion of an upper; c) joining an overlay to the heel portion of the upper; d) positioning a heel cradle having a lasting allowance over a base of the upper; and e) securing a sole to the upper, such that the lasting allowance is disposed between the upper and the sole. While the foregoing manufacturing steps are recited in connection with the illustrated embodiments, the manufacturing steps can vary from application to application as desired, such that greater or fewer method steps can be used in connection with other embodiments.
Joining a memory foam layer to a heel counter includes fixedly attaching the memory foam layer to the concave interior surface of the heel counter. This step can include, for example, laminating the memory foam layer to the heel counter by adhesive. Also by example, this step can include molding the memory foam layer directly to the heel counter. Still further by example, this step can include positioning an intermediate adhesive layer between the heel counter and the memory foam layer, such that that the memory foam layer is indirectly attached to the heel counter. The memory foam layer is fixed with respect to the heel counter in these examples, such that that the memory foam layer cannot be removed without damaging the integrity of the memory foam layer. As noted above, the memory foam layer can be a flat foam sheet. For example, a flat memory foam layer can be applied to the interior of the heel counter, such that the memory foam layer assumes a convex mating surface that bonds with the concave inner surface of the heel counter sidewall. Alternatively, the memory foam layer can be molded with a three-dimensional contour. For example, a pre-shaped memory foam layer can be applied to the interior of the heel counter, being pre-shaped with a convex mating surface that is coextensive with the concave inner surface of the heel counter.
Securing the heel counter assembly to a heel portion of an upper includes gluing the heel counter assembly to the upper in the current embodiment. For example, the heel counter assembly can be glued between a portion of the upper and a liner. In this position, the upper can be strobel lasted such that the upper is closed by a strobel board, thereby providing flexibility in the upper, while the heel counter assembly is securely positioned therein. Joining an overlay about the heel portion of the upper includes attaching the overlay to the exterior of the upper, for example using an adhesive. The overlay can be substantially coextensive with the heel counter or can have a different size and/or shape than the heel counter. In addition, the overlay is formed from the same material as the upper in the current embodiment, but can be formed from a material different from that of the upper in other embodiments as desired. For example, the overlay can be formed from synthetic leather, nylon, or other materials.
The steps of positioning a heel cradle over a base of the upper and securing the sole to the upper provide an article of footwear having a reinforced heel. The heel cradle is rigid in the current embodiment, being molded from thermoplastic polyurethane having u-shaped construction that extends around the heel region of the upper. The heel cradle is also molded to have a shortened intermediate portion that provides a shelf to aid the wearer in removing the article of footwear with downward pressure. The sole can be secured to the upper according to any desired technique, for example by gluing a midsole to the strobel board. Optional further manufacturing steps can include positioning an insole within the upper and over the strobel board, the insole being specifically configured to interact with the heel support assembly. The insole can be manufactured from a material that is highly resistant to compression set. For example, the insole may be manufactured from a material having a compression set of ≤5% after 500,000 compressions and a recovery period of 24 hours. Suitable insole materials include cast-mold polyurethane, pour-molded polyurethane, and expanded thermoplastic polyurethane, for example.
Directional terms, such as “vertical,” “horizontal,” “top,” “bottom,” “upper,” “lower,” “inner,” “inwardly,” “outer” and “outwardly,” are used to assist in describing the invention based on the orientation of the embodiments shown in the illustrations. Further, the terms “medial,” “lateral” and “longitudinal” are used in the manner commonly used in connection with footwear. For example, when used in referring to a side of the shoe, the term “medial” refers to the inward side (that is, the side facing the other shoe) and “lateral” refers to the outward side. When used in referring to a direction, the term “longitudinal direction” refers to a direction generally extending along the length of the shoe between toe and heel, and the term “lateral direction” refers to a direction generally extending across the width of the shoe between the medial and lateral sides of the shoe. The use of directional terms should not be interpreted to limit the invention to any specific orientation. As used above, the term “arch region” (or arch or midfoot) refers generally to the portion of the footwear or sole assembly corresponding to the arch or midfoot of the wearer's foot; the term “forefoot region” (or forefoot) refers generally to the portion of the footwear forward of the arch region corresponding to the forefoot (for example, including the ball and the toes) of a wearer's foot; and the term “heel region” (or heel) refers generally to that portion of the footwear rearward of the arch region corresponding to the heel of the wearer's foot.
The above description is that of current embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. This disclosure is presented for illustrative purposes and should not be interpreted as an exhaustive description of all embodiments of the invention or to limit the scope of the claims to the specific elements illustrated or described in connection with these embodiments. For example, and without limitation, any individual element(s) of the described invention may be replaced by alternative elements that provide substantially similar functionality or otherwise provide adequate operation. This includes, for example, presently known alternative elements, such as those that might be currently known to one skilled in the art, and alternative elements that may be developed in the future, such as those that one skilled in the art might, upon development, recognize as an alternative. Further, the disclosed embodiments include a plurality of features that are described in concert and that might cooperatively provide a collection of benefits. The present invention is not limited to only those embodiments that include all of these features or that provide all of the stated benefits, except to the extent otherwise expressly set forth in the issued claims. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.