ARTICLES OF FOOTWEAR HAVING LINES OF FLEXION

Abstract

The invention herein is directed toward footwear containing a central flex zone comprised of a novel combination of a central flex channel with a central flex element that imparts either bidirectional or multi-directional flexion to the shoe, according to various embodiments, thereby allowing more natural flexibility and allowing all surface contacting members to independently engage and disengage from the contact surface of the user as the wearer's weight shifts. The flex zones also naturally adapt to the amount of stress put on the sole from ground elements, such as rocks or branches that the sole encounters during wear and to adjust to different terrain due thereby being particularly useful in applications such as construction boots and athletic footwear.

Description

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The present invention was not developed with the use of any Federal Funds, but was developed independently by the listed inventor.

BACKGROUND

1. Field

The present invention relates to the field of footwear. More particularly, the invention is directed to a new shoe sole construction wherein the shoe includes a midsole welted between an upper structure and the bottom outsole and wherein the outsole comprises an extruded channel spanning preferably centrally from forefoot to heel area and comprising a shock absorbing cushion that extends and protrudes through the channel within the outsole.

2. Background

Industry reports indicate that as of 2010, the apparel footwear and accessory industry had a market capitalization of approximately fifty-seven billion US dollars. The shoe market evolves continuously to meet the varied needs of the consumers. Conventional articles of footwear traditionally include two primary elements, an upper structure and a sole structure. The upper structure provides a covering for the foot that securely receives and positions the foot with respect to the sole structure. The sole structure is secured to a lower surface of the upper structure and is generally positioned between the foot and the ground in order to cushion and protect the foot while walking. The sole structure may in addition provide traction and control of foot motion.

The upper structure (the “upper”) forms a void on the interior of the footwear for receiving the foot. The void has the general shape of the foot, and access to the void is provided by an ankle opening. Accordingly, the upper extends over the instep and toe areas of the foot, along the medial and lateral sides of the foot, and around the heel area of the foot. A lacing system may be incorporated into the upper to selectively increase the size of the ankle opening and permit the wearer to modify certain dimensions of the upper, particularly girth, to accommodate feet with varying proportions. In addition, the upper may include a tongue that extends under the lacing system to enhance the comfort of the footwear, and the upper may include a heel counter to limit movement of the heel.

The sole structure (the “sole”) is designed to address the particular functionality and use of a shoe. It became one of the objects of the footwear industry to create a sole structure to reduce and control ground reaction forces to the wearer. Lug soles were created as a type of outer sole found on heavy-duty and utility shoes such as hiking boots or work boots. Lug soles are typically thick and designed with deep indentations to improve stability and traction. The pattern of lug soles varies to include indentations such as V-shaped and diamond shaped indentations. Lug soles are most frequently found on construction, fishing, hunting, logging, hiking, and other utility boots. Lug soles are typically made of rubber and some may be injected molded from thermoplastic polymers such as polyvinyl chloride (PVC) or polyurethane (PU). Lug soles are generally slightly wider than the perimeter of the shoe. Though lug soles offer improved traction and stability, they are limited in flexibility and control. Lug soles also have a tendency to accumulate mud in the deep indentations and they can be messy and difficult to clean.

Athletic shoes are a generic name for footwear that is primarily designed for sports or other forms of physical exercise and have come to be used for casual everyday activities. They are also known as sneakers, sneaks, sports shoes, trainers, cross-trainers, jogging shoes, daps, gym shoes, running shoes, runners, tennis shoes, rubber shoes, canvers and other names commonly adapted to particular localities. Attributes of an athletic shoe include a flexible sole with appropriate tread for the function ability to absorb impact. As the industry and design have expanded, the term “athletic shoes” is based as much on the design of the bottom or sole of the shoe as the aesthetics of the top or upper of the shoe. Today's designs include sandal, elevated, and Mary Jane styles suitable for running, dancing and jumping. The shoes themselves are made of flexible compounds, typically featuring a sole made of dense rubber. While the original design was basic, manufacturers have since tailored athletic shoes for the differing purposes for which the shoe can be used. A specific example of a particular design is the spiked shoe developed for track running. Hiking, climbing and mountaineering shoes have become a niche in the athletic shoe industry. Such shoes combine elements of traditional athletic shoes together with elements requiring a more rugged traction and stability.

In addition to functionality, shoes are also designed in different shapes suited to different foot types and gait. Generally, such shoes, especially running shoes, are divided into neutral, over-pronation and under-pronation (supination) shoes to fit the respective foot strike of the wearer. As athletic shoes become more advanced, amateur joggers, as well as marathon runners, are beginning to purchase shoes based on their running or walking style and foot arch. This is often important for injury prevention, as well as to increase athletic efficiency and comfort.

A common form of footwear construction, referred to as welt construction, incorporates a “welt”, which is a strip of leather, rubber, or plastic that is stitched to the upper and the insole of a shoe as an attach-point for the sole. The space enclosed by the welt is then filled with cork or some other filler material (often either porous or perforated, for breathability), and the outsole is both cemented and stitched to the welt. Shoes with other types of construction may also have welts for finished appearance, but they generally serve little or no structural purpose.

Other sole designs have been introduced in order to reduce the welt while rendering flexibility to the wearer. For example, U.S. Pat. No. 6,163,982 discloses a the structure of a conventional shoe sole that has been modified by having its sides bent up so that their inner surface conforms to a shape nearly identical but slightly smaller than the shape of the outer surface of the sides of the foot sole of the wearer, instead of the shoe sole sides conforming to the ground by paralleling it, as is conventional. The shoe sole sides are sufficiently flexible to bend out easily when the shoes are put on the wearer's feet and therefore the shoe soles gently hold the sides of the wearer's foot sole when worn, providing the equivalent of custom fit in a mass-produced shoe sole.

In subsequent construction of footwear, a midsole was introduced that is positioned between the upper and the sole of the shoe in order to render greater comfort to the wearer along with other desirable advantages. For example, U.S. Pat. No. 6,763,609 to Robert Su disclosed a midsole that permits molten outer sole material to flow through the midsole during the molding process and fill the space between the insole and the midsole and thus sandwich the midsole. This technique forms outer soles to be durably and flexibly attached to the upper structure without use of traditional adhesives. The term “outsole” was coined to differentiate the midsole structure from the bottom-most sole structure that comes into contact with the ground.

Numerous designs of footwear have been created that attempt to incorporate a variety of elements into the design and functionality of the shoe to improve flexibility and comfort. U.S. Pat. No. 6,854,198 to Jeffrey Brooks discloses a design having medial, lateral and arch regions that is based on the shape of the toes of the foot in attempting to mimic a foot's natural outline and mobility. U.S. Pat. No. 5,012,597 to Robert Thomasson discloses an athletic shoe sole with a twist flex region positioned below the ball portion of the foot that attempts to construct a flex function which allows the wearer to twist the foot for athletic activities. U.S. Pat. No. 7,124,519 to James Issler discloses a shoe sole having a plurality of adjacent sections made of different materials in order to improve flexibility. U.S. patent application Ser. No. 11/338,601 of Hazenberg et. al. discloses a shoe having a number of fluid-filled chambers in one or more flexion zones of the sole. U.S. Pat. No. 7,650,707 to Campbell et. al. discloses an outsole with flex lines that improve the flexibility functionality of the shoe. U.S. Pat. No. 7,350,320 to Chandler et. al. discloses a shoe with a central flexing point that is focused on a suspension system which allows the heel portion to act as a shock absorber cushioning element. Conversely, U.S. Pat. No. 7,707,748 also to Derek Campbell discloses a shoe with a design that enables the flexing of the forefoot portion of the foot while inhibiting heel movement for improved twisting or swinging action in golf shoes.

The previous examples demonstrate the great focus that has been placed in the shoe industry on either the flexibility of the footwear or the durability of the footwear in its construction. Despite the tremendous size of the shoe industry, it continues to be desirable to create a shoe structure wherein the upper, midsole and the outsole structure operate cooperatively to provide comfortable footwear that is suited for a wide variety of ambulatory activities, such as walking, running, and jumping, as well as being rigid enough for other activities such as hiking, mountaineering and/or utility work among others and wherein the shoe is particularly suited to the specific gait and pressure points of each person. The present invention addresses a number of issues in the shoe industry. The invention features a novel structural configuration of the upper, midsole and outsole structures that allow greater mobility to the foot of the wearer based on the particular movement of the foot of each individual while at the same time allowing traction, control and rigidity for more rugged functionality and use as discussed in greater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary and the following detailed description of the invention will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

FIG. 1 is an illustration of an article of footwear of the invention.

FIG. 2 is a bottom view of the outsole of an article of footwear of the invention.

FIG. 3 is side view of the sole elements of an article of footwear of the invention.

FIG. 4 is a rear view of the sole of an article of footwear of the invention and a rear view of the sole showing the lateral directional flexion of the sole.

FIG. 5 is an alternative illustration of the sole of an article of footwear of the invention.

DETAILED DESCRIPTION

The following detailed description of the invention is made in reference to the accompanying drawings, which form a part hereof, and which show by way of illustration various example structures of the invention. It is to be understood that other specific arrangements of parts, example structures, and embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the present invention. Also, while certain terms may be used in this specification to describe various example features and elements of structures the invention, for example, “heel”, “forefoot”, “midfoot”, these terms are used herein as a matter of convenience, e.g., based on the example orientations shown in the figures and/or a typical orientation during use. The terms “zones” and “regions” are used interchangeably herein. The term downward-facing surface refers to a surface area that is directed and oriented toward the ground.

“Footwear” is used interchangeably herein with “shoe” and means any type of product worn on the feet, and this term includes, but is not limited to all types of shoes, boots, sneakers, sandals, flip-flops, mules, scuffs, slippers, sport-specific shoes (such as golf shoes, tennis shoes, baseball cleats, soccer or football cleats, ski boots, etc.), and the like. Footwear may protect the feet from the environment such as rocks and the weather, and/or enhance a wearer's performance, whether physically, physiologically, medically, or otherwise.

Footwear (10) is depicted in FIG. 1 and includes an upper element (20) and a sole structure (30). Upper (20) is formed from various material elements that are stitched or adhesively bonded together to form an interior void that comfortably receives a foot and secures the position of the foot relative to sole structure (30). Sole structure (30) is secured to the downward-facing surface or lower portion of upper (20) and provides a durable, wear-resistant component for attenuating ground reaction forces as footwear (10) impacts the ground.

For purposes of reference, footwear (10) is divided into two general regions: the exterior lateral zone (80) and an interior or medial region (90), as defined in FIG. 2. Further depicted on FIG. 2, footwear (10) comprises a toe or forefoot region (12), a midfoot region (14) and a heel or rearfoot region (16). Aforesaid regions (80), (90), (12), (14) and (16) are not intended to demarcate precise areas of footwear, but rather are intended to represent general areas of footwear (10) that provide a frame of reference during the following discussion.

Various materials may be utilized in manufacturing the upper element (20). Flexibility, durability and/or temperature regulation of the upper element of a shoe may be regulated by incorporating multiple material layers that include an exterior layer, a middle layer, and an interior layer. A variety of materials are suitable for the upper, including the materials that are conventionally utilized in footwear uppers. Accordingly, the upper may be formed from combinations of leather, synthetic leather, natural or synthetic textiles, polymer sheets, polymer foams, mesh textiles, felts, non-woven polymers, or rubber materials, for example. Portions of the upper can form coextensive layers of material that are stitched or adhesively bonded together. Various layers within the upper element may be joined with adhesives, and stitching may be utilized to join elements within a single layer or to reinforce specific areas of the upper element.

In athletic footwear, materials forming the exterior layer of the upper element may be selected based upon the properties of wear-resistance, flexibility, and air-permeability, for example. The exterior layer of the upper may be formed, therefore, from numerous material elements that each imparts different properties to specific areas of the upper. For example, certain embodiments directed more toward athletic use may have an upper element having a configuration that provides ventilation, thereby cooling the foot and removing perspiration. In footwear intended for rugged activities such as construction or trekking, materials such as leather or canvas elements may be added to the design of the upper. Further, the toe area and the heel area of the shoe may be formed of materials such as leather, synthetic leather, or a rubber material to impart a relatively high degree of wear-resistance. Leather, synthetic leather, and rubber materials may not exhibit the desired degree of flexibility and air-permeability. Accordingly, areas of the exterior of the upper may be formed from synthetic textiles imparting such characteristics if desired in the particular design.

The mechanism for adjusting the fit of upper (20) and accommodating various foot dimensions can be accomplished either by incorporation of a tongue, with separate lacing or by other mechanisms known in the art.

In some embodiments of the invention, the portion of upper (20) in the heel region (12) may incorporate a conventional heel counter formed of a semi-rigid polymer material, for example, to ensure that the heel remains properly positioned with respect to the upper. The heel counter may be located on an exterior of the upper or within the various material elements forming the upper. However, the configuration of the upper and the sole structure (30) does not necessitate the presence of a heel counter. The shoe of the invention may include additional structures or elements, including conventional structures and/or elements known and used in the art, such as securing systems (e.g., laces, buckles, hook-and-loop fasteners, zippers, etc.); heel counters; insole members; interior booties; sock liners; additional impact-attenuating elements; impact-attenuating foam columns; gas-filled bladders, and various others.

The sole structure (30) of the footwear of the invention comprises a layered configuration demonstrated by FIG. 3 that includes an insole (40), a midsole (50), and a shock absorbing cushion structure (60) that is integrally connected to a surface-contacting outsole (70) that together provide both flexibility and abrasion-resistance and traction.

The insole of the invention (40) is a structure that is conventionally a thin, comfort-enhancing member located within the upper and adjacent the plantar (lower) surface of the foot usually added to footwear in order to enhance footwear comfort. Often the insole is formed of a moisture-wicking textile that removes perspiration from the area immediately supporting the bottom of the foot.

A middle layer of the sole of the footwear of the invention, the midsole (50) structure is generally integrally connected to insole (40) illustrated in FIG. 3. A conventional footwear midsole is a unitary, polymer foam structure that extends throughout the length of the foot and may have stiffness or inflexibility that inhibits the natural motion of the foot. The midsole herein has a conventional articulated structure that imparts relatively high flexibility and articulation. The flexible structure of the midsole (in combination with the structure of upper 20) is configured to complement the natural motion of the foot during various activities.

Midsole (50) includes an upper midsole surface (52) and an opposite bottom midsole surface (54). Upper surface (52) is positioned adjacent to the upper (20) and may be secured directly to it, thereby providing support for the foot. Upper midsole surface (52) may, therefore, be contoured to conform to the natural, anatomical shape of the foot. Accordingly, the area of upper midsole surface (52) that is positioned in the heel region (12) may have a greater elevation than the area of upper midsole surface (52) in the forefoot region (14). In addition, the midsole may form an arch support area in midfoot region (16), and peripheral areas of the midsole may be generally raised to provide a depression for receiving and seating the foot. In other embodiments, the midsole may have a non-contoured configuration.

Midsole (50) may be formed from resilient materials such as a lightweight polymer foam material that helps to absorb ground reaction forces and protects the foot from objects that may contact the upper element while simultaneously supporting the outsole. Stability devices can be incorporated into the polymer foam material of the midsole to control the degree of rotational movement of the foot. Examples of stability devices are found in U.S. Pat. No. 4,255,877 to Bowerman; U.S. Pat. No. 4,287,675 to Norton et al; U.S. Pat. No. 4,288,929 to Norton et al; U.S. Pat. No. 4,354,318 to Frederick et al.; U.S. Pat. No. 4,364,188 to Turner et al; U.S. Pat. No. 4,364,189 to Bates; and U.S. Pat. No. 5,247,742 to Kilgore et al. In addition to stability devices, conventional midsoles may include fluid-filled bladders, as disclosed in U.S. Pat. Nos. 4,183,156 and 4,219,945 to Rudy, for example.

The Shock Absorbing Cushion

The footwear of the invention comprises a shock absorbing cushion element (60) that according to the invention functions together with outsole (70) in a novel configuration and design in order to render superior foot motion control while rendering shock absorption, durability and traction. The shock absorbing cushion (60) is recessed between the midsole (50) and the outsole (70). As illustrated in FIG. 2 and FIG. 4, in the preferred embodiment of the invention, the shock absorbing cushion element (60) comprises one central protruding flex zone segment, the central flex element (62) that extends longitudinally from the forefoot portion or toes (14) (e.g., at or near the toe area of the sole (30)) to the rearfoot portion or heel (12) (e.g., at or near the rear heel area of the sole (30)). Central flex element (62) is integrally recessed within the central flex channel (72) forming two halves or regions of outsole structure (70).

Midsole (50) and the shock absorbing cushion of the invention (60) are preferably joined through a mechanical interface rather than an adhesive or chemical interface. The primary element of a conventional midsole is a resilient, polymer foam material, such as polyurethane or ethylvinylacetate, which extends throughout the length of the footwear. The properties of the polymer foam material in the midsole are primarily dependent upon factors that include the dimensional configuration of the midsole and the specific characteristics of the material selected for the polymer foam, including the density of the polymer foam material. Similarly, suitable polymer foam materials for the shock absorbing cushion element (60) of the invention include ethylvinylacetate (“EVA”) or polyurethane (“PU”) that compress resiliently under an applied load to attenuate contact surface reaction forces. Conventional polymer foam materials are resiliently compressible, in part, due to the inclusion of a plurality of open or closed cells that define an inner volume substantially displaced by gas. By varying these factors throughout the midsole, the relative stiffness, degree of ground reaction force attenuation, and energy absorption properties may be altered to meet the specific demands of the activity for which the footwear is intended to be used.

Depending on a desired design aesthetic, the shock absorbing cushion (60) of the invention may be either open and exposed to the external environment, such that it is distinctly visible and identifiable from the side view of the shoe; or it may be hidden within another material (such as in impact-attenuating material) or partially hidden in such a material, without departing from this invention. The thicknesses of the midsole and of the shock absorbing cushion are depicted graphically in FIG. 3 as thickness dimension (55) and (65), respectively.

The Outsole

The outsole of a shoe is generally the sole layer that is in direct contact with the ground. The outsole (70) of the invention is secured to a lower surface of the shock absorbing cushion (72) to provide wear-resistance. As in conventional outsoles, the outsole of the invention (70) is fashioned from a durable, wear-resistant material. Suitable materials for outsole (70) include abrasion-resistant materials such as any of the conventional rubber materials that are utilized in footwear outsoles, such as carbon black rubber compound, blown rubber, or a combination of blown and carbon rubbers.

The outsole (70) sometimes includes texturing in order to improve traction of the footwear, illustrated in FIG. 5. Likewise, the outsole (70) of the invention forms the ground-contacting element of the footwear of the invention. In the preferred embodiment of the invention, the outsole (70) is divided longitudinally into two regions or halves extending from the forefoot (12) to the heel (16). As illustrated in FIGS. 2 and 5, the region of the shoe closest to the exterior of the foot shall be termed the lateral region (80) and the region of the shoe closer to the interior of the foot shall be termed the medial region (90). The line or area of division between the two halves or regions of the outsole (70) forms the central flex channel (72) of the invention through which protrudes the central flex element (62) of the invention and extends from the forefoot (12) to the heel (16) and illustrated in FIGS. 2 and 5 or as will be discussed hereinbelow.

The thickness of the outsole is defined as the dimension that extends between the shock absorbing cushion (60) and the outer bottom surface of the outsole (70) that is in contact with the ground. The thickness of the outsole may vary along the longitudinal length of the midsole. The thickness is depicted graphically in FIG. 3 as thickness dimension (75). One skilled in the relevant art will recognize that a variety of thickness dimensions and variations will be suitable for the outsole depending on the use for which the footwear is contemplated and designed.

The Central Flex Zone

The shock absorbing cushion element of the invention (60) is designed such that it protrudes between the two longitudinal regions of the outsole, the lateral region (80) and the medial region (90) through the central flex channel (72) thereby creating the central flex element (62). The central flex element is visible from the bottom view of the shoe as illustrated in FIG. 5. Together, the central flex channel (72) and the central flex element (62) form the central flex zone which provides a line of flex in the sole (30) and divide outsole (60) into the lateral region (80) and the medial region (90). The central flex zone acts as the center flexing point for the sole. Whereas the conventional footwear outsole is usually a unitary element of polymer foam, the central flex channel (72) of the invention forms a flexion line in the outsole and, therefore, imparts a direction of longitudinal flex in the sole. The manner in which the sole structure (30) is consequently able to flex or articulate as a result of the novel central flex zone disclosed herein, is graphically depicted in FIG. 4. The central flex zone acts as a live hinge for the sole allowing the sole to move in a birdlike flapping motion of its wings.

In general, during the time that the foot is in contact with the ground, the motion of the foot during walking is such that the foot typically rolls from the outside or lateral side to the inside or medial side, a process called pronation. That is, normally, the outside of the heel strikes first and the toes on the inside of the foot leave the ground last. The separation of footwear (10) into the lateral (80) and medial (90) regions creates a structure that allows the lateral and medial zones to move independently of each other allowing each of the regions of the outsole to bend in response to elements on the ground and thereby imparting bidirectional flexibility and flexion.

The welt has always given boots its tough and durable trait. However the welt takes away from a boots overall flexibility and ultimately adds to the overall weight of the boot. Cement construction in is widely used by the athletics footwear market for its flexibility and light weight. The problem with cement construction is that it does not impart toughness and durability. In order to address the limitations presented by the welt, the outsole of the invention utilizes the strength and durability found in the welt. Thereby, in contrast to conventional footwear of the prior art, footwear of the invention directed to applications such as construction boots and trekking boots can handle the toughness and durability required on the construction site and yet imparts a more natural flexibility and comfort to the footwear. The central flex zones allow the shoe to feel more like an extension of the foot, flexing in places at which the foot naturally wants to flex rather than fighting the foot's natural motion which is the problem with common construction and trekking boots. Further, the footwear of the invention is able to adjust to different terrain due to its ability to flex.

In one preferred embodiment of the invention, the weight of the welt is countered by using a polyurethane injection molded midsole. This design eliminates the weight that is traditionally tacked on by the standard solid rubber lug outsole. Adding the strength of the good year welt construction to the design combines the best qualities of athletic and occupational footwear.

In the preferred embodiment, the lateral and medial regions form two separate segments on the outsole of the footwear of the invention. However, in yet another embodiment of the invention, lateral region (80) and medial region (90) are connected at the heel (16) of the footwear thereby forming one continuous segment. In another embodiment, lateral region (80) and medial region (90) are connected at the forefoot segment (12) of the footwear thereby also forming one continuous segment. Also contemplated is an embodiment where the lateral and medial regions are connected at both the heel (16) and toe (12) regions.

Though preferably the individual central flex channel (72) and the corresponding central flex element (62) creating the line of flex extend completely from the forefoot (12) to the rearfoot (16) regions, embodiments are contemplated where the central flex element (72) extends and protrudes only partially through the central flex channel (72) i.e., the length of the central flex element (62) being less than the length of the central flex channel (72) along the outsole of the shoe.

Optionally, central flex element (62) comprises a longitudinal central flex groove which imparts yet additional longitudinal bidirectional flexibility and flexion. The flexible footwear of the types described above allow independent movement of the lateral and/or medial segments of the outsole member (e.g., independent movement or rotation with respect to one another about the lines of flex) to thereby allow more of the outsole to remain in contact with the ground e.g., as compared to support structures that do not include such flexibility and independently and relatively movable regions, which may improve safety and functionality during operation on a construction worksite and advantages during certain sporting activities such as for example during a golf or baseball swing (or other swinging activities) as weight tends to shift, and the wearer's center of gravity moves from the center or medial side to the lateral side and/or moves from the lateral side to the medial side. Moreover, the increased lateral stability and/or decreased lateral flexibility as compared to the medial side's stability and/or flexibility characteristics provide excellent support and/or comfort during various moving, twisting or swinging actions.

According to some embodiments of the invention, central flex element (62) (and central flex channel (72)) is positioned not precisely within or toward the longitudinal center of the foot but either more laterally toward the lateral region (80) or more medially toward the medial region (90), respectively. A configuration wherein central flex zone (62) is positioned medially provides a shoe where the lateral side of the foot is made less flexible and/or more stable than its medial side. Such a design may be particularly useful for individuals having specific gait characteristics, for example those individuals who tend to place more weight toward the lateral part of the foot as they walk.

Embodiments of the invention are provided wherein the thickness of the outsole (70) differs throughout the length of the shoe particularly where the thickness of the lateral region (80) differs from the thickness of the medial region (90). The variation in the thicknesses between the lateral and medial regions of the outsole with respect to one another allow for yet further control and comfort to the wearer, such as, for example, for individuals having specific preferences or medical requirements for the height of their foot arches.

The central flex channel (72) may extend for any desired length in the outsole without departing from the invention. The channel may run along the entire length of the shoe or along only a partial length of the shoe. The width of the central flex channel is from about 2 to about 20 mm wide, illustrated as dimension (75) in FIG. 4, preferably from 4 mm to about 14 mm wide. Though preferred, not all of the central flex channel (72) and the corresponding central flex element (62) in a given shoe need have the same dimensional characteristics. The invention herein will be operable as long as the dimensions of the central flex channel (72) are greater than the dimensions of the central flex element (62) such that the central flex element (62) is able to protrude through the central flex channel (72). However, in the preferred embodiment, the dimensions of the central flex channel and the central flex element are approximately equal so as to prevent rocks, soil or other ground materials to accumulate in the central flex channel which may cause discomfort to the wearer and potential puncture of the sole structure at the recessed central flex channel.

The thickness of the central flex element (62) is preferably approximately equal to or less than the thickness of the outsole of the shoe. The thickness of the central flex zone may vary along its longitudinal length. The thickness is depicted graphically in FIG. 4 as thickness dimension (63). For example, dimension (63) in the forefoot region (12), may be, for example, approximately 4 mm to 15 mm. One skilled in the relevant art will recognize, however, that a variety of thickness dimensions and variations will be suitable for the central flex element.

The width of the central flex element (62) of the invention is defined by dimension (65) demonstrated in FIG. 4 and is preferably typically approximately equal to the width of the central flex channel (72) in order for the central flex element (62) to protrude through the central flex channel (72). The width of the central flex element is preferably between 2 mm and 20 mm, more preferably between 4 mm and 15 mm, and more preferably between 6 mm and 10 mm. A relatively thin thickness of the central flex element will, in general, possess more flexibility than flex element having a greater thickness. Variations in the thickness may, therefore, be utilized to modify the flexibility of the sole structure in specific areas of the foot. For example, the forefoot region may be configured to have relatively high flexibility by forming a central flex element with a lesser thickness while a relatively low flexibility may be imparted to the midfoot region by forming the central flex element with a greater thickness. Similarly, an intermediate flexibility may be imparted to the heel region by forming a central flex element with a thickness that is between the thicknesses of the forefoot region and the midfoot region.

In other embodiments of the invention, multiple central flex elements may be introduced dividing the outsole of the shoe into various regions, for example, further separating and subdividing each of the lateral region (80) and the medial region (90). In an example structure, provided is a shoe comprising three central flex elements, as illustrated in FIG. 5, having subdivided forefoot sub-lateral zones (82) and (84) and sub-medial zones (92) and (94), wherein each of the zones provide discrete areas of the sole structure such that they are each individually movable about the lines of flex (64) and (66) with respect to one another to allow the various regions to independently engage and disengage from a contact with the ground elements. The dimensions of the central flex channel (72) and corresponding central flex element (62) may vary along the overall length, width, and/or depth of an individual zone segment.

While referred to as extending in the “longitudinal direction”, the central flex zone need not extend exclusively in a direction of a longitudinal center line of the sole structure. Rather, as shown in FIG. 2, the term “longitudinal direction”, as used herein in this context, means that the central flex channel (72) and the corresponding central flex element (62) creating the line of flex defined thereby extend predominantly in the longitudinal direction, e.g., generally from the shoe's front or toe (12) toward its back or heel (16), and may optionally extend in a curved manner in order to, for example, to correspond to the location(s) of a typical foot's lines of flex and/or flexibility in the longitudinal direction or simply for a desirable fashion element. When such multiple longitudinally extending central flex elements are present, the various segments need not be parallel to one another and they need not extend in precisely the same directions, in the same arch or curvature, or at the same dimensions (e.g., to the same depth in the base level, at the same width or length, etc.)

Similarly, while referred to as extending in the “lateral direction”, the central flex channel (72) and the corresponding central flex element (62) creating the line of flex need not extend exclusively in a direction laterally across the sole structure. Rather, as shown in the figures, the term “lateral direction”, as used herein in this context, means that the central flex channel (72) and the corresponding central flex element (62) creating the line of flex defined thereby extend predominantly in the lateral direction (e.g., generally from the shoe's lateral side toward its medial side), optionally in a curved manner (e.g., to correspond to a typical foot's lines of flex and/or flexibility in the lateral direction), as illustrated in FIGS. 2 and 5. Additionally, if desired, it is not necessary for an individual central flex channel (72) and the corresponding central flex element (62) to extend completely across the sole. They may extend any desired distances. When multiple laterally extending central flex channels are present (e.g., additional central flex channels in the heel and forefoot portions, etc.), the various central flex channels need not be parallel to one another and they need not extend in precisely the same directions, in the same curvature, or at the same dimensions (e.g., to the same depth in the base level, at the same width or length, etc.). Optionally, if desired, the central flex elements and lines of flex in the outsole structure may correspond to typical areas of flex or joints in a wearer's foot. Also, if desired, lines of flex may be provided in the heel area in at least some example sole structures. Such designs allow the wearer to adjust more naturally to a particular terrain, where for example the lateral side may flex more than the medial side and vise versa. Such footwear allows more of the sole to remain in contact with the ground providing a solid base for support for movement and activity.

Additional Elements

The footwear according to some examples of this invention may include additional features or structures. If desired, some portions of the shock absorbing cushion (60) and/or of the outsole (70) may be at least partially filled with another material, e.g., a material softer than a material making up a major portion of the shock absorbing cushion or the outsole, to further promote the flexibility characteristics of the shoe's structure while preventing wearer feel of ground elements.

The footwear further may include plural ground penetrating traction elements, commonly referred to as “traction lugs” (78), illustrated in FIG. 5. The shape of the traction lugs is determined by the positions of the various treads, or spaces that extend upward into the outsole material and extend between the sole elements forming an articulated configuration of the bottom ground-facing surface of outsole. For example, the outsole (70) may include one or more traction lugs in its forefoot or heel portions, extending in the lateral or longitudinal directions on the bottom surface of the outsole. Preferably the traction lugs will be placed at locations corresponding to natural foot flexibility, to provide additional flexibility and lines of flex and to further improve traction capability in desired applications. Typical embodiments of the invention will comprise outsoles having a “breasted” heel with lateral tread to render improved traction to the shoe, thus allowing full range of motion such as walking, running or climbing. Accordingly, tread marks are formed and distributed over the bottom surface of the outsole to selectively vary the degree of stretch and flexibility in specific portions of the outsole. In addition to functionality, the traction lugs and tread marks are often applied to vary the overall aesthetics (e.g., color) of the outsole of the shoe as desirable to consumers.

Additional traction elements, such as golf spikes, may be attached at various locations on the exterior surface of the outsole. These traction elements may be mounted to the outsole member in any desired manner, including via threads, other retaining systems, etc., including through the use of conventional mounting systems that are known and used in the art. Any type or arrangement of traction elements may be used without departing from the invention. Such traction elements may be included as part of the sole structure in any desired manner without departing from the invention, such as by integrally molding them into the sole structure along with other portions of the sole or by attaching them to the sole structure (e.g., by adhesives, cements, screws, clasps, retaining elements, other mechanical connectors, etc.) If desired, according to at least some examples of this invention, traction elements of the types and/or in the arrangements shown in U.S. Pat. Nos. 6,817,117 and/or 6,705,027 may be used without departing from this invention, each of which is incorporated herein by reference. Additionally or alternatively, if desired, any indentations, weld areas, or other recessed structures on the exterior surfaces of the outsole may include additional support structures, such as plastic supports (e.g., PEBAX® (a polyether-block co-polyamide polymer available from Atofina Corporation of Puteaux, France), which can help make the lateral side more stable and less flexible than the medial side. In addition, other ways of providing lateral support and/or medial flexibility may be used, in place of or in combination with the various examples described above, without departing from the invention. Also, if desired, various types of heel units, midsole elements, or impact-attenuating elements or structures may be provided without departing from the invention, such as conventional foam or other impact-attenuating materials, columnar shock absorbing type elements and the like.

It is one advantage of the invention that if components of the sole (30) of the invention becomes worn or otherwise damaged, the damaged component may be replaced without the necessity of replacing the undamaged component, and the damaged component may be more easily recycled. For example, since the outsole will be generally formed from a polymer material, following significant use, the polymer foam material may experience compression set or otherwise degrade or become significantly worn. Rather than dispose of the footwear (10), either the shock absorbing cushion (60) or the outsole (70) may be properly recycled and replaced with an alternate component, respectively, thus extending the lifespan of the footwear. In the event that the lateral region (80) of the outsole becomes punctured, only the lateral outsole component can be replaced, without replacing the medial region (90) of the outsole and in lieu of replacing the entire outsole. Furthermore, the outsole may be interchanged with alternate components to suit a particular activity or a preference of an individual.

Manufacturing

A number of manufacturing methods are suitable for forming the sole elements of the invention. Conventional footwear construction generally follows two methods, welted construction and molded construction. In the invention herein, the outsole may be formed as a unitary element with the central flex channel (72) subsequently formed through an incision process, for example. The outsole may also be molded such that the central flex channel is formed during the molding process. Suitable molding methods for the outsole, the shock absorbing cushion, and the midsole include injection molding, pouring, or compression molding, for example. In each of the molding methods, a blown polymer resin is placed within a mold having the general shape and configuration of the desired structural element. The mold includes thin blades that correspond with the positions of the flex channels. The polymer resin is placed within the mold and around each of the blades. Upon setting, the structural element is removed from the mold, with the desired dimensions being formed during the molding process.

The central flex channel (62) of the invention may be provided in the outsole (60) structure during the manufacturing process, such as during a sole member molding process, by a cutting action (e.g., using knives, blades, lasers, etc.), and/or in any other manner, including in conventional methods known and used in the art for the manufacture of outsoles. Any desired types of materials may be used for the structures of the shock absorbing cushion (60) and central flex element (62) and the outsole (70) structures, including rubber or polymeric materials (such as thermoplastic polyurethanes), including materials that are known and conventionally used in the art. As some more specific examples, the outsole material may be constructed from a rubber material, e.g., having a hardness of 60 to 90 Shore A (and in some examples, 64-70 Shore A), and the shock absorbing cushion (60) material may have about the same level of hardness, or perhaps a bit softer (optionally made from rubber or a thermoplastic polyurethane material). The material of the shock absorbing cushion (60) and central flex element (72) need not be the same material as the outsole (70), and can be made of either a harder or a softer material. Of course, a wide variety of materials, hardness, combinations of materials, and/or combinations of hardness may be used without departing from the invention.

As discussed above, the sole (30) is permanently secured to the lower portion of the upper (20). A variety of attachment techniques may be utilized for permanently securing the outsole to the sides of the upper, including stitching, adhesive bonding, thermobonding, or a combination thereof, for example.

The various structural features and the various aspects of the invention described above may be used in any desired combinations, permutations, and sub-combinations without departing from the invention. It will be apparent to those skilled in the art that various modifications may be made to the present invention without departing from the intended scope of the invention since it is not considered limited to the specific embodiments described in the specification and drawings.

Claims

1. An article of footwear having a forefoot region, a midfoot region, a heel region, a lateral region, a medial region, an upper structure and a sole structure, the sole structure comprising:

a midsole positioned along the longitudinal length of the downward-facing surface of the upper structure and connected thereto; and

a shock absorbing cushion integrally connected to the downward-facing surface of the midsole; and

an outsole integrally connected to the downward-facing surface of the shock absorbing cushion, said outsole comprising at least one flex channel in the form of an aperture in the outsole; and

wherein the shock absorbing cushion extends downward and protrudes through and along said flex channel of the outsole forming a corresponding flex element.

2. The article of footwear of claim 1, wherein the flex channel is oriented in a longitudinal direction of the footwear from the forefoot region to the heel region.

3. The article of footwear of claim 2, wherein the flex channel extends substantially centrally in the longitudinally direction of the footwear.

4. The article of footwear of claim 1, wherein the flex channel is oriented in a substantially lateral direction of the footwear from the medial region to the lateral region of the footwear.

5. The article of footwear of claim 1, wherein the footwear comprises a plurality of flex channels in the outsole with corresponding flex elements.

6. The article of footwear of claim 3, wherein the medial region and the lateral region are partially connected to one another.

7. The article of footwear of claim 6, wherein medial region and the lateral region are connected to one another at the heel or at the toe or both.

8. The article of footwear of claim 1, wherein the outsole extends partially upward from the sole structure to the upper structure to form the welt of the footwear.

9. The article of footwear of claim 1, wherein the thickness of the shock absorbing cushion varies along the forefoot region, the midfoot region, the heel region, the medial region and/or the lateral region.

10. The article of footwear of claim 1, wherein the width of the flex element is approximately equal to the width of the flex channel.

11. The article of footwear of claim 1, wherein the thickness of the flex element is approximately equal to the thickness of the flex channel.

12. The article of footwear of claim 1, wherein the thickness of the shock absorbing cushion is from about 4 to about 15 mm.

13. The article of footwear of claim 1, wherein the thickness of the flex element is from about 8 to about 10 mm.

14. The article of footwear of claim 1, wherein the shock absorbing cushion comprises polyurethane or ethylvinylacetate.

15. The article of footwear of claim 1, wherein the outsole further comprises traction lugs.