Patent Application
20140290098
The present invention relates to footwear and more particularly to a sole assembly for an article of footwear.
The technical performance of shoes, boots, sandals and other articles of footwear is dependent in large part on the sole assembly. The sole assembly not only provides a protective barrier between the wearer's foot and the ground, but can also play an important role in the way that energy is utilized by the wearer. The construction of a sole assembly is complicated by the fact that the human gait cycle transitions through four different phases. Although gaits vary to some degree between different people and different activities, a typical human gait includes the following phases: (1) heel impact (or heel strike), (2) heel to toe transition, (3) forefoot compression and (4) toe off. The soles in many shoes suffer in that they are configured to focus only on absorbing force during heel strike and providing cushioning to the forefoot region.
A variety of conventional sole assemblies are reported to collect energy and return that energy during different phases of the gait cycle. For example, some existing sole technologies include a longitudinally extending flexible plate that is incorporated into the sole. Generally speaking, the plate bends to store energy during the forefoot compression phase of the gait cycle, and then straightens during the toe off phase of the gait cycle to return the stored energy. As another example, a variety of sole technologies are available with a flexible and resilient spring in the heel region. Unlike foams, which compress, these springs are configured to bend under a load and to return to their original shape as the load lessens. The size, shape and configurations of these types of springs vary. Generally speaking, these types of springs are intended to store energy during heel impact and to return that energy during the heel to toe transition and forefoot compression phases of the gait.
Although there are a variety of existing sole technologies that utilize a flexible plate or a heel spring, the performance characteristics of a sole assembly can vary dramatically depending upon the specific way in which these technologies are implemented in a sole. If not implemented properly these technologies can prove to be a detriment rather than an aid.
The present invention provides a sole assembly that includes a combination of components that are configured to provide assistance through all four phases of the gait cycle. In one embodiment, the sole assembly generally includes a heel spring and a flex plate. The heel spring may be disposed beneath the heel region of the sole. The flex plate may extend from the rear of the sole forwardly through the arch region into the forefoot region. For example, the flex plate may extend to a point roughly below the metatarsal heads of the wearers foot. In one embodiment, the heel spring and flex plate are part of a single sole component. For example, the sole component may be molded from TPU or other relatively hard plastic materials.
In one embodiment, the sole component may also include a heel cup that is shaped to closely receive a heel. The heel cup may be integral with the heel spring and flex plate. In one embodiment, the heel cup is an extension of the flex plate and it includes a heel extension that extends upwardly along a gradual curve to embrace the wearer's heel and provide an enhanced forefoot lever. The heel cup may have upper flanges that extend forwardly in an arcuate path selected to closely follow the expected shape of the wearer's heel. In one embodiment, the heel extension follows a gradual curve that is undercut in the sense that it curves back in a forward direction above a portion of the wearer's heel to help resist separation of the wearer's foot from the sole component.
In one embodiment, the heel spring is an elliptical spring having upper and lower arched segments joined at opposite ends. A portion of the upper arched segment may be generally coextensive with the flex plate. In one embodiment, the elliptical spring may be cantilevered in a rearward direction beyond the flex plate and heel cup. In one embodiment, the upper arched segment and/or the lower arched segment may be shaped to provide controlled rigidity in different directions. For example, in one embodiment, the lower arched segment may in lateral cross section be shaped to define a central rail that extends in the longitudinal direction to provide the lower arched segment with enhanced longitudinal stiffness.
In one embodiment, the elliptical spring may include one or more resilient stoppers disposed within the internal void of the spring. The stopper(s) may extend into the internal void from the upper arched segment or the lower arched segment. In use, the resilient stopper(s) prevent the upper arched segment from bottoming out against the lower arched segment. The resiliency of the stopper(s) may be selected to provide the desired resistance to further compression. In those embodiments that include stoppers, the elliptical spring may include a plurality of resilient stoppers spaced apart from front to rear in a longitudinal direction. The height of the stoppers may be selected for functional reasons. For example, taller stoppers will allow the spring to collapse less before engagement with the stoppers. The relative height of the stoppers may also vary for functional purposes. For example, in one embodiment, the height of the stoppers may increase toward the rear of the sole. In one embodiment, the elliptical spring may include two rows of stoppers. For example, the elliptical spring may include a first row of stoppers along the lateral side of the sole and a second row along the medial side of the sole. In one embodiment, each row of stoppers includes three stoppers spaced-apart along an arcuate path.
In one embodiment, the sole assembly includes a heel outsole disposed under the resilient spring, and the resilient stopper(s) are extensions of the heel outsole that are fitted up through corresponding apertures in the elliptical spring. Although the stoppers may be an integral part of the outsole, they may alternatively be separately manufactured.
In one embodiment, the sole assembly includes a forefoot outsole disposed under the forward end of the flex plate. For example, an article of footwear incorporating the present invention may include a forefoot region into which the forward end of flex plate extends. The forefoot outsole may cover the undersurface of the forefoot region, including a significant portion of the forward end of the flex plate. In one embodiment, the central or arch region of the sole component may be uncovered by the outsole, thereby making it readily visible.
The sole assembly of the present invention may be incorporated into essentially any footwear construction and may be combined with other sole components, such as a midsole, insole or footbed. In one embodiment, the sole component and associated outsole parts are cemented or otherwise secured to the undersurface of upper having a closed bottom. A footbed may be fitted into the upper.
The present invention provides a sole assembly that is capable of providing high performance throughout all four stages of a typical gait cycle. During the heel strike phase, the elliptical spring compresses and undergoes deformation, which among other things cushions the impact and stores some of the impact energy. If deformation of the spring is great enough, the spring engages the resilient stoppers, which provide increasing resistance to further deformation. During the heel-to-toe transition phase, the elliptical spring “bounces” back propelling the foot forward. If compressed, the resilient stoppers may also return energy during the heel-to-toe transition phase. During the forefoot compression phase, the flex plate bends along its length (particularly in the forward section) to store energy as the foot flexes. During the toe-off phase, the bent flex plate returns to its original non-deformed shape, thereby returning the stored energy. Depending on the momentum and angle of toe-off, this energy may help to propel the wearer forward when running or upward when jumping. In use, the present invention may provide enhancements to both speed and jumping. The heightened heel section of the flex plate provides a substantial lever to aid in compression (e.g. bending) of the flex plate during the forefoot compression phase. The resilient stoppers provide enhanced performance in part because they do not impede initial compression of the elliptical spring, but only become relevant after the elliptical spring has compressed an amount that can be predetermined. The present invention can be readily tuned for a variety of different application by adjusting the characteristics of the various sole assembly parts. For example, the rigidity and resiliency of the material forming the elliptical spring, the flex plate and the stoppers can be adjusted to provide different sole characteristics. The real and relative heights of the stoppers can be adjusted to also impact the performance characteristics of the sole assembly.
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.
An article of footwear in accordance with an embodiment of the present invention is shown in
Although the present invention is illustrated in the context of an athletic shoe. It may, however, be incorporated into essentially any type or style of footwear, including shoes, boots and sandals. It should be noted that 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 (i.e. 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(s).
For purposes of disclosure, the present invention is described in the context of an athletic shoe 10 having an upper assembly 12 formed using a strobel construction. A sole assembly 14 in accordance with the present invention may, however, be combined with essentially any type or style of upper construction capable of being suitably joined with the sole component 20. The upper assembly 12 of the illustrated embodiment includes an upper 15 formed from one or more layers of material that are shaped to form an enclosure of roughly the size and shape of a wearer's foot. The upper 15 of this embodiment may include quarters that form the sides and a vamp that closes the top. Foxing and other trim or extra material may be added to the upper 15 as desired for functional or aesthetic reasons. In this embodiment, the upper 15 includes a tongue 38 and a closure system 40 to facilitate fitting and removal of the shoe 10 on a wearer's foot. The tongue 38 and closure system 40 are generally conventional and therefore will not be described in detail. The upper 15 may include a heel counter. The heel counter may be a generally conventional heel counter configured to provide control and stability to the wearer's heel. For example, the upper 15 may include a rigid or semi rigid insert that forms a sidewall in the heel region to seat the wearer's heel. In some embodiments, the heel counter may be eliminated from the upper 15. In such embodiments, the heel cup 28 (described in more detail below) of the sole component 20 may function as a heel counter. In the illustrated embodiment, the bottom of the upper 15 is closed using an insole board 16 (the upper surface of which is represented by a phantom line in
As noted above, the sole assembly 14 of shoe 10 generally includes a footbed 18, a sole component 20 and an outsole 22. The footbed 18 of this embodiment is a generally conventional footbed that is manufactured from a soft resilient material, such as EVA, PU or a gel material. The footbed 18 may be configured to be removably fitted into the upper 15 atop the insole board 16. Alternatively, the footbed 18 may be secured to the top of the insole board 16, for example, by cement or adhesive. The size, shape and configuration of the footbed 18 may vary from application to application. Although referred to as a footbed, footbed 18 may alternatively be referred to as an insole or inner sole. In addition or as an alternative to the footbed 18, the sole assembly may include a midsole (not shown) or other sole component disposed below the footbed 18. In embodiments that incorporate a midsole, the midsole may be disposed above or below the flex plate 18, or the flex plate 18 may be embedded or partially embedded in a midsole (not shown).
The sole component 20 of the illustrated embodiment generally includes a flex plate 24, a heel spring 26 and a heel cup 28. In this embodiment, the flex plate 24, heel spring 26 and heel cup 28 are formed as a single unitary component. However, they could be separately manufactured, if desired. In the illustrated embodiment, the flex plate 24 is a longitudinally extending plate-like component configured to generally correspond with the shape of the undersurface of a wearer's foot. The flex plate 24 may extend from the heel region of the sole assembly 14 to the forefoot region of the sole assembly. The peripheral edge of the flex plate 24 in the forefoot region is represented by broken line P in
In the illustrated embodiment, the shape of the flex plate 24 varies from region to region. In this embodiment, the flex plate 24 may include a forefoot region 42, an arch region 44 and a heel region 46. As shown, the forefoot region 42 of the flex plate 24 may be generally planar following a relatively slight curve configured to correspond with the general shape of undersurface of a wearer's forefoot (See
In the illustrated embodiment, the heel cup 28 is an extension of the flex plate 24. As shown in
As noted above, the sole component 20 also includes a heel spring 26. The heel spring 26 is generally disposed beneath the flex plate 24 and/or heel cup 28 in the heel region of the sole component 20. As shown, the heel spring 26 may extend higher than the forefoot section 32 of the flex plate 24 to provide a raised “shelf” for the heel of the wearer's foot. The heel spring 26 may be an elliptical spring that is disposed in the heel of the shoe 10 generally below the heel of the wearer's foot. In the illustrated embodiment, the heel spring 26 includes an upper arched segment 60 and a lower arched segment 62. The two arched segments 60, 62 are joined at opposite ends to provide a closed cross sectional shape. Although referred to as an “elliptical” spring, it should be understood that the heel spring need not be precisely elliptical in cross section. In fact, the heel spring may have essentially any alternative shape, including shapes that are not elliptical. For example, the heel spring may be have a closed shape, such as circular, oblong, square, hexagonal, triangular, or “∞”-shaped, or an open shape, such as “C”-shaped, “S”-shaped, “Z”-shaped or sinusoidal. In the illustrated embodiment, the flex plate 24, heel spring 26 and heel cup 28 are integrally formed as a single unitary component. In the embodiment, the upper arched segment 62 is an extension of the flex plate 24. For example, as shown, a forward portion of the upper arched segment 60 may be defined by and be essentially coextensive with the flex plate 24. The shape of the arched segments 60 and 62 may vary from application to application for functional or aesthetic reasons. For example, the shapes of upper and lower arched segments 60 and 62 may be selected to provide the desired resilient compression. In the illustrated embodiment, the upper and lower arched segments 60 and 62 cooperatively define an irregular ellipse. For both the upper and lower arched segments 60, the radius of curvature may vary along the segment. For example, in the illustrated embodiment, the upper arched segment 60 and the lower arched segment 62 increase in radius toward the rear of the sole component 20. As a result, the elliptical spring 26 is somewhat oblong with the rear end being larger than the front end. The upper arched segment 60 and the lower arched segment 62 may or may not be symmetrical with respect to one another. As perhaps best shown in
In the illustrated embodiment, the heel spring 26 is cantilevered beyond the rearward end of the flex plate 24. The amount of cantilever may vary from application to application to vary the performance characteristics of the sole assembly 14. Alternatively, the heel spring 26 may not be cantilevered, but may instead co-terminate with the flex plate 24.
The elliptical spring 26 of this embodiment defines a central void 36 and includes resilient stoppers 30 positioned in the void 36. In use, the resilient stoppers 30 function primarily to prevent the upper arched segment 60 from bottoming out against the lower arched segment 62 under load. When the elliptical spring 26 has been sufficiently deformed by a load, the upper and lower arched segments 60 and 62 will “close onto the stoppers 30 and the stoppers 30 will provide enhanced resistance to further compression of the heel spring 26. The resiliency of the stoppers 30 may be selected to provide the desired resistance to further compression. The number, size, shape and configuration of the stoppers may vary from application to application. In those embodiments that include stoppers, the elliptical spring may include a plurality of resilient stoppers 30 spaced apart from front to rear in a longitudinal direction. In the illustrated embodiment, the elliptical spring 26 includes two rows of stoppers 30. As shown, the elliptical spring 26 may include a first row of stoppers 30 arranged near the lateral side of the sole component 20 and a second row of stoppers 30 arranged near the medial side of the sole. In the illustrated embodiment, each row of stoppers 30 includes three stoppers 30. As perhaps best shown in
In the embodiment of
In the illustrated embodiment, the stoppers 30 are manufactured from the same material (e.g. the outsole material). In alternative embodiments, the stoppers 30 may be manufactured from different materials to allow the performance characteristics of the sole assembly 14 to be tuned. For example, stoppers 30 positioned closer to the rear of the shoe may be harder than those positioned closer to the front. As another example, the medial row of stoppers may have a different hardness than the lateral row of stoppers to control pronation or supination.
In the illustrated embodiment, the stoppers 30 extend into the internal void 36 from lower arched segment 62. The stopper 30 may, however, extend from the upper arched segment 60 and/or the lower arched segment 62.
In the illustrated embodiment, the sole component 20 is manufactured from thermoplastic polyurethane elastomer (“TPU”), nylon or a polymer blend that includes nylon and/or TPU. The sole component 20 may, however, be manufactured from essentially any relatively hard polymer, such as nylon or an elastomer, or from other materials capable of providing the desired functional characteristics, such as fiber-reinforced polymers. Suitable elastomers may include thermoplastic elastomers or thermoset elastomers. Examples of suitable fiber reinforced polymers may include epoxy, polyethylene or polyester thermosetting plastic reinforced with carbon, glass and/or aramid fibers.
As discussed above, the sole assembly 14 of the illustrated embodiment includes an outsole 22 disposed below the sole component. The outsole 22 is intended to provide a ground engaging surface and may have essentially any configuration. In the illustrated embodiment, the outsole 22 includes a forefoot section 32 and a heel section 34. The outsole 22 may, however, include essentially any number of parts. For example, the outsole 22 may be a single component that extends the full length of the sole. On the other hand, the outsole 22 may include even more than two separate parts. In the illustrated embodiment, the forefoot section 32 of the outsole 22 is secured to the undersurface of the upper 15 and the undersurface of the forefoot section 32 of the flex plate 24. For example, the forefoot section 32 of the outsole 22 may be cemented or otherwise secured to the bottom of the upper 15 and the sole component 20 in the forefoot region of the shoe 10. The size, shape and configuration of the forefoot section 32 of the outsole 22 may vary, but in the illustrated embodiment the forefoot section 32 defines a rectangular cutout 66 that exposes the flex plate 24 well into the forefoot region.
In the illustrated embodiment, the heel section 34 of the outsole 22 is secured to the undersurface of the heel spring 26. More specifically, the heel section 34 may be cemented or otherwise secured to the undersurface of the lower arched segment 62 of the heel spring 26. In this embodiment, the stoppers 30 are formed integrally with the heel section 34 of the outsole 22. For example, the heel section 34 may be formed with protrusions that are configured to be fitted through the apertures 70 in the lower arched segment 62 into the void 36 to form the stoppers 30. Although not shown, each stopper 30 may be larger in diameter than the corresponding aperture 70 and may therefor include an intermediate shoulder that engages the upper surface of the lower arched segment 62. To facilitate installation, each stopper 30 may have a reduced diameter neck (not shown) that is configured to be seated in the aperture 70 when the stopper 30 is properly fitted into place. The height of the neck may be roughly equal to the thickness of the lower arched segment 62. This provides a mechanical interlock between the stoppers 30 and the heel spring 26. In use, the intermediate shoulder (not shown) rests upon and distributes the forces created by downward loads onto the lower arched segment 62, thereby preventing those loads from being communicated through the apertures 70 to the underlying outsole 22.
The outsole 22 may have essentially any desired tread pattern. In the illustrated embodiment, the forefoot section 32 includes a plurality of lugs 76 or other tread details arranged inside the periphery of the forefoot section of the flex plate 24. These lugs 76 may help to communicate forces between the ground and the flex plate 24. In the illustrated embodiment, the heel section 34 of the outsole 22 includes a plurality of circular lugs 78 or other tread details positioned immediately below the stoppers 30.
In the illustrated embodiment, the sole assembly 20 is configured so that the heel section 34 of the outsole 22 projects roughly 2.0 mm below the projected ground line G, as shown by reference line B in
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.
