A shoe includes an upper and a sole each with a forward region with a forward center of loading and a rear region with a rear center of loading. The sole includes an insole, a midsole, and an outsole. Two integrated suspension elements include an upper suspension arm and a lower suspension arm that are joined at respective ends. The integrated suspension elements are disposed between at least a portion of the midsole and the outsole. The integrated suspension elements each have a center of compression generally aligned with the forward center of loading and the rear center of loading. The integrated suspension elements extend substantially laterally across a width of the midsole and the outsole.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates generally to a shoe that includes one or more suspension elements.

Description of Prior Art

Shoes traditionally include an upper that receives a foot of a wearer (also represented by a last) and a sole connected to the upper. The sole generally includes an insole underneath the foot/last, as well as a midsole and/or an outsole that form a bottom portion of the shoe.

When a wearer walks or runs within a shoe, the load of the wearer's body is exerted on a heel portion of the shoe with a downward force from the heel of the wearer. The downward force is exerted from a center of the wearer's heel through a center of the heel portion of the shoe, or a rear center of loading. As the wearer progresses through the movement, the load of the wearer's body is transferred, and exerted on a forefoot portion of the shoe with a downward force from the ball of the foot of the wearer. The downward force is exerted from a center of the wearer's ball of the foot through a center of the forefoot portion of the shoe, or a forward center of loading.

Using shoes for an extended period of time can cause fatigue to the wearer as the shoe materials break down from the downward force of the wearer's body weight and force applied to the shoe components. The resulting fatigue can include fatigue to the muscles, tendons, ligaments, and/or cartilage of not only the feet and legs of the wearer, but also the torso and other parts of the body.

To reduce or eliminate fatigue to the wearer's body, as well as improve longevity and integrity of shoes, various improvements have been made to shoe components to reduce impact forces from a change in loading when a wearer uses a shoe, or to reduce “bottoming out” of conventional shoe materials. Once such improvement is shown in U.S. Pat. No. 7,334,351 (“the '351 patent”), which is incorporated herein by reference. The '351 patent provides a shoe with a suspension element to improve efficiency of the shoe and reduce neuromuscular fatigue.

The present invention provides a shoe preferably with two suspension elements that improve performance over existing shoes, such as over the shoes described in the '351 patent. The subject shoe preferably includes carbon fiber suspension element(s) with a mechanical midsole that is more efficient in whole body systemic oxygen consumption than conventional foam midsole shoes. The subject suspension element(s) efficiently compress and improve timing of heel-to-toe energy transfer when a wearer uses a shoe to walk or run, particularly in an athletic shoe.

SUMMARY OF THE INVENTION

The present invention provides a shoe that includes an upper and a sole. The upper and the sole each include a forward region with a forward center of loading and a rear region with a rear center of loading.

The sole generally includes an insole, a midsole, an outsole and two integrated suspension elements. The integrated suspension elements each preferably include an upper suspension arm and a lower suspension arm that are joined at respective ends. The integrated suspension elements are disposed between at least a portion of the midsole and the outsole. The integrated suspension elements each have a center of compression. Each center of compression is generally aligned with the forward center of loading and the rear center of loading, respectively. The integrated suspension elements extend substantially laterally across a width of the midsole and the outsole. The midsole and the outsole include a plurality of layers and material adjacent to the integrated suspension elements.

The two integrated suspension elements preferably include a forefoot suspension element and a heel suspension element. The forefoot suspension element preferably includes a length that is greater than a length of the heel suspension element; and the heel suspension element preferably includes a height that is greater than a height of the forefoot suspension element.

The material of the midsole surrounds at least a portion of the upper suspension arm. The material of the outsole surrounds at least a portion of the lower suspension arm. At least one integrated suspension element includes two intersecting arcs defined by the upper suspension arm and the lower suspension arm forming a mandorla, defining a hollow suspension region therebetween. At least one integrated suspension element also preferably includes a joint that joins the upper suspension arm and the lower suspension arm at respective ends of the upper suspension arm and the lower suspension arm. The joint may include at least one elastomer, polymer, or mechanical hinge. At least one integrated suspension element may include a carbon suspension core. The carbon suspension core includes variably-arranged polypropylene fibers.

The two integrated suspension elements of the shoe may include a forward integrated suspension element disposed below the forward region of the upper and the sole, and a rear integrated suspension element disposed below the rear region of the upper and the sole. Each of the forward integrated suspension element and the rear integrated suspension element include a hollow, mandorla-shape defined by the upper suspension arm and the lower suspension arm joined by at least one joint configured to join the upper suspension arm and the lower suspension arm at respective ends of the upper suspension arm and the lower suspension arm.

The forward integrated suspension element includes a center of compression generally aligned with the forward center of loading. The midsole of the shoe includes an openable cavity extending a lateral width of the forward integrated suspension element disposed between a portion of the midsole and a portion of the upper suspension arm of the forward integrated suspension element. The openable cavity extends longitudinally from an end of the upper suspension arm of the forward integrated suspension element, to another point along a length of the upper suspension arm. The midsole also includes a fabric border extending along a perimeter of the openable cavity. The fabric border abuts a portion of midsole and the upper suspension arm of the forward integrated suspension element.

The rear integrated suspension element includes a center of compression generally aligned with the rear center of loading. The rear integrated suspension element preferably includes a compressible layer disposed between a portion of the outsole and the lower suspension arm of the rear integrated suspension element. The compressible layer extends along a length of the lower suspension arm.

The sole of the shoe preferably includes at least one cavity disposed across a portion of a lateral width of the rear integrated suspension element disposed between a portion of the sole and a portion of the upper suspension arm of the rear integrated suspension element. The sole may include a plurality of cavities disposed generally equidistant across the lateral width of the midsole disposed between a portion of the sole and a portion of the upper suspension arm of the rear integrated suspension element.

Another object of the invention can be attained, at least in part, through a shoe including an upper with a forward region with a forward center of loading and a rear region with a rear center of loading, an insole, and a midsole that includes at least one convex suspension arm integrated with a portion of the midsole. The at least one convex suspension arm includes a composite material having a greater resistance than the plurality of layers and materials of the midsole.

According to one embodiment, the shoe also includes an outsole with at least one concave suspension arm integrated with a portion of the outsole. The at least one concave suspension arm has a composite material having a greater resistance than the plurality of layers and materials of the outsole. A first end of the at least one convex suspension arm is joined with a first end of the at least one concave suspension arm, and a second end of the at least one convex suspension arm is joined with a second end of the at least one concave suspension arm. The at least one convex suspension arm and the at least one concave suspension arm are configured to form a mandorla-shaped suspension element integrated between the midsole and the outsole. At least one joint element secures the first and second ends of the at least one convex suspension arm with the first and second ends of the at least one concave suspension arm.

The at least one joint may include an elastomer disposed therebetween at least one pair of the first ends and the second ends. The at least one joint may also include a bead of silicone disposed adjacent to an overlap of at least one pair of the first ends and the second ends. The at least one joint may further or alternatively include a polymer hinge with a first insert and a second insert. The first end or the second end of the at least one convex suspension arm plugs into the first insert, and the first end or the second end of the at least one concave suspension arm plugs into the second insert. The at least one joint may also include an elastomer hinge where the first end or the second end of the at least one convex suspension arm can plug into a portion of the elastomer hinge, and where the first end or the second end of the at least one concave suspension arm can plug into another portion of the elastomer hinge.

The at least one concave suspension arm may include a suspension bumper aligned with the center of compression. The suspension bumper protrudes into a hollow interior of the mandorla-shaped suspension element. The mandorla-shaped suspension element may include a suspension booster in a hollow interior of the mandorla-shaped suspension element aligned with the center of compression. The suspension booster is operatively attached to a portion of the at least one convex suspension arm and extends to a portion of the at least one concave suspension arm. The mandorla-shaped suspension element may further include a retaining rod extending laterally across at least one of the convex suspension arm and the concave suspension arm, and a plurality of links to connect to the retaining rod through the center of compression and protrude into a hollow interior of the mandorla-shaped suspension element.

Yet another object of the subject invention can be attained by a shoe with an upper including a forward region with a forward center of loading and a rear region with a rear center of loading, an insole including a high density sock layer, a midsole including a plurality of layers and materials, and an outsole including rubber.

The shoe also includes a first mandorla-shaped suspension element with an upper suspension arm and a lower suspension arm. The shoe further includes a second mandorla-shaped suspension element with an upper suspension arm and a lower suspension arm. The outsole of the shoe may include a two-piece outsole, where a portion of the two-piece outsole is removable, and where the second mandorla-shaped suspension element is replaceable with another mandorla-shaped suspension element.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a shoe having a pair of improved integrated suspension elements. The shoe of the subject invention improves lateral (torsional) stability in carbon fiber composite elliptical suspension elements. At least one previous shoe design uses generally longitudinal fiber to create a suspension effect, but said suspension effect causes shoes to roll excessively, to varying degrees. The present invention is directed to a shoe having a substantially higher degree of lateral stability.

FIG. 1shows a shoe100according to one embodiment of this invention. The shoe as shown includes an athletic shoe, although the present invention may be applied to any number or variety of shoe-types. The shoe100generally includes an upper102and a sole104. The upper102can house a last (not shown) to generally represent a wearer's foot that may fit inside the shoe100. The shoe100includes a forward region106, generally represented by a front portion of the shoe100, where the ball of the foot and toes of a wearer would go. The shoe100also includes a rear region110, generally represented by a rearward portion of the shoe100, where the heel of a wearer would go. In a preferred embodiment of this invention, the shoe100is modeled on an anatomical last.

The sole104of the shoe100includes an insole104a, a midsole104b, and an outsole104c, as shown inFIG. 2. The insole104aincludes a portion of the shoe closest to the last (or the wearer's foot). The outsole104cincludes a portion of the shoe closest to the ground. The midsole104bis displaced between the insole and the outsole. The sole also includes one or more integrated suspension elements114,116. In the embodiment shown inFIG. 2, the sole includes a forefoot suspension element114and a heel suspension element116. The forefoot suspension element114is in the forward region106of the shoe, aligned with a forward center of loading108. The forward center of loading108is defined by an area of pressure and force for when a wearer is in a portion of a stride where the weight of the wearer is occurring in the forward region of the shoe.

The heel suspension element116is in the rear region110of the shoe, aligned with a rear center of loading112. The rear center of loading112is defined by an area of pressure and force for when a wearer is in a portion of a stride where the weight of the wearer is occurring in the rear region of the shoe.

In comparison with the prior art, the forefoot suspension element114according toFIG. 2is preferably significantly larger than the prior art, or oversized, and is designed to have much greater torsional lateral stability than earlier, smaller suspension elements. With an oversized forefoot suspension element, the shoe provides greater linearity of suspension loading and more energy transfer from heel to forefoot. Other embodiments of the invention may further include modifying the sizes and/or quantities of the suspension element(s).

FIG. 3shows a bottom view of the outsole104c. Both the forward center of loading108and the rear center of loading112are shown across the intersection of a centerline of the outsole105and cross-sectional lines B and D, respectively.

FIG. 4Ashows a lateral side view of the sole104of the shoe. Additional details of the integrated suspension elements114,116are seen here. Each of the suspension elements114,116include an upper or convex suspension arm118and a lower or concave suspension arm120. The upper suspension arm118is adjacent to, and surrounded by, layers126of the midsole104b. The lower suspension arm120is adjacent to, and surrounded by, layers128of the outsole104c. The upper suspension arm118and lower suspension arm120connect to form a suspension element114,116that is a mandorla shape. The terms “convex” and “concave” are intended to be defined relative to a generally planar walking or running surface.

The mandorla shape that forms a suspension element according to the present invention may comprise include an almond, marquise, vesica piscis, or other similar shape that is generally formed by two arcs (in this case, a convex arm and a concave arm) that connect at respective pointed ends to form the mandorla shape therebetween.

The mandorla shape includes a hollow suspension region138between the suspension arms118,120. The hollow region138extends through a lateral width W of the outsole and midsole (shown inFIG. 6), through to the medial side of the sole104as shown inFIG. 4B. Each suspension element114,116preferably includes a center of compression124. The center of compression124is aligned with a respective center of loading108,112.

In one embodiment of the invention, the forefoot suspension element is preferably greater than 65 mm long from front to rear, between the ends that join the upper and lower suspension arms. The forefoot suspension element is also preferably more than 9 mm high through a center of the hollow suspension region between the lower suspension arm and upper suspension arm. In one embodiment a forward suspension element includes a length of at least 60-100 mm, with a height of at least 7-20 mm.

In one embodiment of the invention, the rear suspension element is preferably at least 65 mm long from front to rear, between the ends that join the upper and lower suspension arms. The rear suspension element is also preferably at least 14 mm high through a center of the hollow suspension region between the lower suspension arm and upper suspension arm. In one embodiment a rear suspension element includes a length of at least 60-95 mm, with a height of at least 12-30 mm. As such, the forefoot suspension element114preferably includes a length130that is greater than a length132of the heel suspension element116. The heel suspension element116preferably includes a height136that is greater than a height134of the forefoot suspension element114.

FIGS. 5A and 5Bshow close-up cross-sectional lateral views of the forefoot or forward suspension element114. As shown, the midsole104bincludes an openable cavity144between a portion of the midsole104band a portion of the upper/convex suspension arm118of the forefoot suspension element114. The openable cavity144extends laterally a width146(seeFIG. 6) of the suspension element114and extends longitudinally from an end122aof the upper suspension arm118to another point148along a length158of the upper suspension arm118. When a wearer engages the forward center of loading108, by placing his/her weight on the ball of the foot, the forward suspension element114is engaged, and the openable cavity144can open (as shown inFIG. 1).

To maintain the integrity of the openable cavity144, the midsole104balso includes a fabric border150that extends along a perimeter152of the openable cavity144. The fabric border150abuts a portion of the midsole104band a portion of the upper suspension arm118of the forward integrated suspension element114. The fabric border150preferably includes a tightly woven fabric or polymer sheet approximately 0.25 mm thick, although other thicknesses may be used. By outlining the perimeter152of the openable cavity, the fabric border150forms a v-shape (as shown in the detail view ofFIG. 5A) in a cross-sectional or side view of the sole104.

FIG. 6shows a partially-transparent top view of the shoe100according to one embodiment of the invention. Here, a portion of the sole104includes at least one cavity160disposed across a lateral width of the rear integrated suspension element116, at the rear region110of the shoe100. In some embodiments of the invention, the shoe100may include a plurality of cavities160disposed generally equidistant across the lateral width of a portion of the midsole. The plurality of cavities160are preferably arranged between a portion of the sole104and a portion of the upper suspension arm118of the rear integrated suspension element116.

The plurality of cavities160are preferably arranged at a leading edge of the rear region110of the shoe. As shown inFIG. 6, the plurality of cavities160may include four evenly spaced suspension flex pockets to the leading edge of a heel portion of the midsole104b. These pockets or cavities are preferably about 12 mm wide by 13-15 mm deep and 6 mm high at one end. The three-dimensions may vary across each individual cavity. The cavities may generally be rectangularly-shaped as shown, although other shapes may be used as well. The cavities allow the upper suspension arm of the rear suspension element to flex more evenly and symmetrically in tandem with the lower suspension arm of that suspension element.

Both the at least one cavity160of the rear region110of the shoe, as well as the openable cavity144of the forward region106of the shoe are shown in the cross-sectional view of the sole104ofFIG. 7. The midsole104band the outsole104ceach include a plurality of layers126,128within the shoe100. A portion of such layers are similarly shown in the toe or front view of the sole104ofFIG. 8, or the heel or rear view of the sole104ofFIG. 10.

Additionally,FIG. 9shows a cross-sectional view of the sole104from cross-sectional line D shown inFIGS. 3-7.FIG. 11shows a cross-sectional view of the sole104from cross-sectional line B shown inFIGS. 3-7.FIG. 12shows a cross-sectional view of the sole104from cross-sectional line C shown inFIGS. 3-7. Such views include representations of the multiple layers126,128and materials of portions of the sole104according to various embodiments of the invention.

One embodiment of the present invention includes a suspension-specific anatomic last. This last places the big toe of a wearer in a position where the toe can essentially “roll off” of a forefoot suspension element so that the big toe (and the rest of the foot following) can land in a more powerful, anatomically aligned position when compared to the prior art. This leads to a more powerful toe-off portion of a stride when a user is walking or running.

FIG. 13Ashows a cross-sectional top view of a conventional last (a foot representation) according to the prior art. Such a conventional last misaligns forefoot anatomy by putting lateral pressure on a side of the big toe and pinky toes, leading to improper toe-off tracking. A conventional last pushes the big toe towards the midline of the foot which loses both energy transfer and stability in completing a stride. When the big toe is shoved over towards the midline, this encourages and can cause pronation of the ankle. This can cause plantar, ankle, knee, hip or iliotibial pain. This also causes a less efficient transfer of energy during the critical toe-off portion of a stride and can lead to instability during a subsequent heel strike. As a result, it is common for runners to have large calluses on the medial side of their big toes.

FIG. 13Bshows an anatomic last with a forefoot suspension accommodation according to one embodiment of the invention. Here, a surface area A of the last allows for room to splay out toes, correcting the toe-off tracking of the prior art. A forward suspension element according to one embodiment is preferably aligned with a knuckle of a user's big toe. Forward alignment of the big toe is enabled by the larger toe box of the anatomic last. There is ample room for the big toe to plant itself naturally and firmly during a toe-off portion of a stride.

The last according to the embodiment shown inFIG. 13Bworks integrally with a hinge and forefoot suspension to guide a force of suspension energy release through the big toe and into the ground efficiently. This leads to conservation in an energy path of a stride of a wearer, from a heel-in through a toe-off portion of a stride.

The anatomic last according to the subject invention also contributes to a medial/lateral suspension area balance. By treating the shoes “flight dynamics” more like a boat or airplane, the shoe according to the subject invention can improve lateral pressure distribution on suspension elements along a midline of a foot, running from the second metatarsal to the heel calcaneus bone. This distribution measures and equalizes an area of suspension on either side of the second metatarsal to calcaneus line.

This is unlike lasts according to the prior art which encourage placing suspension elements in a position that creates a dynamically unbalanced medial/lateral pressure loading. Such lasts, such as those discussed in the '351 patent, are deficient on the medial side of the shoe. The result is excessive pronation of the ankle and knee with patellar pain and iliotibial band pain.

Another object of the subject invention that is an improvement over the prior art includes medial side suspension elements107that preferably protrude from an outside of a footprint of the sole to create a centering effect, such as shown inFIG. 14B. In the prior art, as shown inFIG. 14A, the area of a footprint of the sole is different on the medial side versus the lateral side of the foot. In the subject invention, according toFIG. 14B, the area A of the footprint is equalized on both sides. This is particularly beneficial in a woman's shoe, and such a shoe can have a greater area on a medial side of the shoe to accommodate a woman's hip q-angle.

Women's shoes according to the subject invention will preferably have an increased medial/lateral loading balance on the medial side of a shoe to provide better stride stability for a more acute femur to patella “Q-angle.” This provides an additional value in reducing torsional stress in joints during running. The medial/lateral loading balance may further be modified to ensure better stride stability for a variety of types of shoes, whether particularly designed for men, women, children, a particular shape or size of foot, a unique condition, or any combination thereof. The loading balance may be modified to suit an individual's needs to provide a better stride stability for any type of wearer.

FIGS. 15Aand B show versions of isolated suspension elements according to the prior art. Such versions are further shown and explained in FIGS. 22 and 25 of the '351 patent.FIG. 15Ashows a suspension element with primarily longitudinal fibers, coupled with a small amount of lateral fibers142a. This suspension element, according to the prior art, contains less than 5% of lateral fibers, whereas suspension elements of the claimed invention preferably include 20% or more lateral fibers.

FIG. 15Bshows a suspension element with all longitudinal fibers142b. This suspension element, according to the prior art, contains at least 95% longitudinal fibers, whereas suspension elements of the claimed invention preferably include less than 80% longitudinal fibers.

Suspension elements according to embodiments of the subject invention may include a totality of fibers biased at angles and amounts so as to create resistance to lateral collapse, or increased torsional lateral stability.

FIGS. 16Aand B show versions of isolated suspension elements114,116according to the present invention. Each of the suspension elements114,116shown, include a lateral width146that extends through a portion of the sole when inserted into a shoe.FIG. 16Ashows polypropylene fibers142(or similar) wrapped longitudinally around apex joints140of the suspension element114,116. This reduces or eliminates epoxy micro-cracking from concentrated stress in these joint areas of the suspension elements. A two-piece suspension element (including upper and lower suspension arms) also aids in reducing or eliminating epoxy micro-cracking in the fibers of the suspension element.

As such, the material(s) of the suspension element(s) according to the subject invention, preferably closely mimic properties of toughened epoxy matrix resins. One such example includes high-modulus polypropylene fibers wrapped longitudinally around the inside and outside of a carbon suspension core. The polypropylene fibers reinforce toughened epoxy and resist onset of micro cracking of the epoxy, which also prevents zipper fiber failures across the suspension element. As shown inFIG. 16B, the polypropylene fibers142for the suspension element may be laid up as unidirectional fiber, fabric, filament wound on a mandrel, or other constructions as well.

FIGS. 17A-Cshown additional details of a suspension element114,116according to the subject invention.FIG. 17Ashows a suspension element114,116with an upper suspension arm118and a lower suspension arm120. Ends122a,122bof the upper suspension arm118are joined with ends122c,122dof the lower suspension arm120, as shown inFIG. 17B. The respective ends of the suspension arms are joined at joints140with an elastomer162(discussed further below inFIG. 18A). The elastomers162are preferably made of natural rubber, approximately 1.5 mm thick, although other materials and thickness may be used. The upper suspension arm118is preferably made of 10 layers of alternating biased unidirectional carbon fiber.

FIG. 17Aalso shows the suspension element with biased fibers142c. Suspension elements according to the prior art contained less than 5% of biased fibers, whereas suspension elements of the claimed invention preferably include up to 100% of biased fibers. The biased fibers of the claimed invention are preferably biased against one another at varying angles of 10°-40°, more preferably 20°-30° in order to maximize torsional lateral stability. The angles of the fibers are determined relative to a longitudinal heel-to-toe direction representing an angle of 0°. The biased fibers may be biased at consistent angles, or they may also be biased at varying, different angles, throughout areas of the suspension element(s).

A top view of the upper suspension arm118is further shown inFIG. 17C. Here, the lateral width146of the suspension element is observed. Also shown are additional fiber reinforcements141that may be placed at desired regions of the suspension element. As shown, these reinforcements141may be ideally placed on areas of the suspension element most prone to stress and wear, such as a center109of a suspension arm and/or at the respective ends122a-dof a suspension arm as shown. In addition, the upper and/or lower suspension arms of a suspension element may include near-flat centers109with a modest radius. These near-flat centers reduce or eliminate suspension position sensitivity (or “hot spots”) for the wearer. These centers also allow the shoe to accommodate a wider range of foot anatomy due to a less critical foot positioning.

To further improve the integrity of suspension elements in the subject invention, the two-piece design (including the upper/convex suspension arm joined with the lower/concave suspension arm) may be joined in a variety of ways. One such example of a two-piece apex joint hinge design140includes an elastomer162as shown inFIG. 18A(as also shown inFIGS. 17A-Babove). The elastomer162preferably includes latex rubber and may also include a type of glue to attach respective ends of the suspension arms.FIG. 18Bshows another joint hinge design140that includes a silicone bead164. In this example, fiber to form the upper and lower suspension arms is cut to leave overlapping tabs that bear an opposing carbon. These overlapping tabs can be configured to attached to one another and include the silicone bead164to maintain said attachment.

FIG. 18Cshows yet another joint hinge design140that includes a polymer hinge166. The polymer hinge166is preferably a live hinge, made of nylon, polypropylene or similar material. The hinge166includes a first insert168and a second insert170. The inserts168,170are arranged so that an end122bof one suspension arm118plugs into the first insert168, and an end122dof another suspension arm120plugs into the second insert170.

FIG. 18Dshows another joint hinge design140that includes an elastomer hinge172. The elastomer hinge172is preferably a live hinge made of a rubber material, or another material with similar properties. The elastomer hinge172includes a first portion174that accepts an end of a suspension arm, and a second portion176that accepts another end of a suspension arm.

By separating the suspension elements of the subject invention into upper and lower halves with apex joint elastomers, polymers or mechanical hinges, flex patterns and ratios can be altered between upper and lower halves (arms) of suspension elements, and the hinge area can flex naturally with little energy loss. The joints that connect the suspension arms may be mechanical, elastomeric, polymer live-hinges, or any other suitable hinge design.

One such flex pattern/altered ratio according to an embodiment of the subject invention includes the suspension element116shown inFIG. 19. The heel suspension element116includes an upper suspension arm118that has a composite stiffness that differs from a lower suspension arm120. The suspension arms118,120have an asymmetrical composite stiffness to balance total stiffness of the sole104of the shoe. This balance is achieved as the upper suspension arm118is less stiff and/or more flexible in comparison to the lower suspension arm120because layers126of the midsole104bpreferably include EVA, which adds overall stiffness.

The upper suspension arm118of the suspension element116is nested into the midsole104band thus is correspondingly stiffer overall than the lower suspension arm120. The stiffness of the upper suspension arm118is therefore reduced compared to the lower suspension arm120, to achieve an equal spring rate from both arms in conjunction with the sole104. This reduces or eliminates unbalanced failure stresses between the upper and lower arms of suspension elements throughout the shoe.

Another advantage of the shoe of the subject invention over the prior art, includes an improved variable drop with regard to including oversized suspension elements. A conventional foam shoe has a higher heel than toe height. This is referred to as “drop”. A variable drop is shown inFIGS. 20A and 20B.FIG. 20Ashows the shoe100with a forefoot and heel suspension element114,116where the forefoot suspension element114is partially compressed (where weight is pressed on the forward region106of the shoe100).FIG. 20Bshows the shoe100where the heel suspension element116is partially compressed (where weight is pressed on the rear region110of the shoe100).

Compressing the rear region110or heel portion of the shoe during stride entry (or landing), can drop the heel of the shoe by approximately 3-15 mm. The actual drop of the heel will vary according to each individual wearer of the shoe. This “variable drop” is accomplished by a compressible travel of one or more of the oversized suspension elements114,116. By compressible travel, a height of a suspension element is capable of being reduced, reducing the area of the hollow suspension region138. Preferably, the variable drop varies between the forefoot and heel suspension elements, in conjunction the varying sizes (in length and in height) between the forefoot and heel suspension elements. An example is discussed below atFIG. 28B.

The “variable drop” geometry of one or more of the suspension elements aids a foots motion through a stride, resulting in a smoother and more efficient stride when running or walking. By minimizing abrupt stride dynamic “starts and stops” the lower leg/foot is better guided through a stride with less energy loss and greater stability.

To further improve energy transfer and lateral stability, embodiments of the invention can include a reduced foam/fabric thickness in portions of the sole, as shown inFIG. 21. Localized areas X, Y of the sole104around the suspension elements114,116can be modified with a lower ride height. A lower ride height provides increased efficiency through more direct energy transfer from a wearer's metatarsal and calcaneus bones to the forefoot114and heel116suspension elements. Shoes according to the prior art include 10-12 mm of foam between a wearer's foot and suspension elements. InFIG. 21, this material thickness is decreased down to preferably 5-8 mm for increased lateral stability and increased energy transfer to the suspension elements.

FIG. 22shows an isolated view of the heel suspension element116. The heel suspension element116includes an outsole104cof rubber layer(s)128and an additional compressible shear layer154. The compressible layer154sits between the outsole104cand the lower suspension arm120of the heel suspension element116. The compressible layer154extends along a length156of the lower suspension arm120. The layer154is preferably a soft, compressible layer that shears or displaces laterally to reduce and spread contact abrasion loads on the rubber outsole104c. The material of the layer154preferably includes a very low durometer and is laterally stretchy, and is generally made from EPDM or a neoprene elastomer, although other materials may be used. The function of this layer is to decelerate the heel upon ground contact and smooth the heel entry into a walk/run stride.

The compressible layer154may be made a bright or contrasting color, in comparison with the other adjacent shoe components. As such, this colored layer can act as an outsole wear indicator. The appearance of the layer can indicate to the wearer that repair or replacement of the outsole of the shoe is needed.

Energy transfer to the suspension elements of the shoe is further enhanced with a high-density sock liner186, as shown inFIG. 23. The insole104aincludes the sock liner186, to sit underneath a last/foot in the upper of the shoe. The liner preferably includes a high-density foam with a low compressibility to more efficiently transfer energy from a foot through to at least one suspension element.

In another embodiment of the invention, as shown inFIG. 24, a suspension element114,116includes a suspension bumper178. The suspension bumper178protrudes from at least a portion of the lower suspension arm120and is preferably made from EVA foam. The bumper178limits suspension compression and possible damage from heavier wearers landing on curbs and other hard-edged surfaces. The suspension bumper178may include a single protrusion that extends through a portion, or all of the suspension element. The suspension bumper178may also be a small, isolated protrusion in a center of the suspension element, or the suspension element may include multiple suspension bumpers displaced throughout various portions of the hollow interior of the suspension element. In any case, the suspension bumper is preferably round, as shown inFIG. 24, although other desirable shapes and/or sizes may be used as well.

In another embodiment of the invention, as shown inFIG. 25, a suspension element114,116includes a suspension booster180. The suspension booster180is aligned with the center of compression124of the suspension element, attached from a portion of the upper suspension arm118to a portion of the lower suspension arm120. The booster180preferably extends through a center of the hollow interior138of the suspension element, appearing essentially perpendicular to the ground, although a variation of positions and angles of orientation may be used as well.

The suspension booster180is preferably an EVA or urethane component provided to increase load capacity and/or ride quality of the shoe. The suspension booster can firm up the respective suspension element for heavier runners or those needing firmer suspension on the medial side of the shoe to reduce pronation, for example.

The suspension booster may be inserted to fit into a desired suspension element or may be affixed with integrated hangers or self-stick into the interior of the suspension element. Additionally, suspension boosters with varying spring rates and/or other properties may be provided and inserted into medial and lateral sides of the suspension elements, adjusted to customize the shoe for an individual wearer.

In another embodiment of the invention, as shown inFIGS. 26A and 26B, a suspension element114,116includes a retaining rod182that extends through the center109of a portion of the lateral width146of the upper suspension arm118. The retaining rod182includes a plurality of links184that extend from the retaining rod182, perpendicular to the retaining rod, through the hollow interior138of the suspension element. The links184preferably include a stainless steel cable to pull the upper and lower arms of the suspension element towards each other.

The retaining rod and corresponding links can be added to one or more suspension elements of a shoe to pre-load a static spring rate into the shoe. For example, in one embodiment of the shoe without a retaining rod and links, a suspension element with a height of 25 mm includes a spring rate of 640 lb/in. This suspension element could be modified to 28 mm in height for a spring rate of 25.2 lb/mm Using a retaining rod and links to reduce the height of the suspension element back to 25 mm, the resulting suspension element still maintains 640 lb/in in spring rate, while also having 25.2 lb/mm by 3 mm in height reduction, resulting in 75.6 lb of preload. This results in a stride with higher energy and a greater “snap” when pressure is applied and let off of the suspension elements. In some embodiments the links may be asymmetrically adjusted to allow for tuning of gait stability and to best support an individual wearer's anatomical characteristics.

Another embodiment of the invention includes modifications to a hinge operation angle with the forefoot suspension element.FIG. 27shows a schematic representation of a hinge activation angle111, pronation, neutral orientation, and medial extension107achieved with a forefoot suspension element in the forward region106of the shoe. By varying this identified hinge operation angle the shoe can compensate, and correct, for overpronation by steering the forefoot into correct alignment with the forefoot suspension element.

The various properties of the suspension elements of the present invention as discussed above, contribute to a variety of benefits over the prior art.FIG. 28Ashoes a side view of a shoe according to the prior art. As shown, this shoe has almost no angle of incidence—spacing between the heel and/or toe portions of the shoe and the ground. A forward suspension element according to this shoe includes a length of 65 mm by a height of 9 mm, with 4 mm of compressible travel. A rear suspension element according to this shoe includes a length of 65 mm by a height of 14 mm, with 7 mm of compressible travel. As further discussed in the '351 patent, such suspension elements were created with little awareness of the need for torsional lateral stability, and they also reduced total energy storage potential by a significant degree.

As such, the present invention provides improved suspension elements with increased energy storage by modifying the sizes of the suspension elements, as well as the materials and construction. Suspension elements include a radius on a bottom of the shoe, known as a “rocker”. In the prior art, the rocker radius is approximately 35 inches. In the present invention, the shoe preferably includes a rocker radius of approximately 20 inches. The lower rocker radius benefits smoothness of energy transfer of the shoe during a stride by accommodating better leg movement geometry compared to the prior art.

FIG. 28Bshows a side view of a shoe according to an embodiment of the present invention. By increasing the sizes and lateral stability of suspension elements, the shoe of the present invention includes a much smaller radius rocker contour with a much larger angle of incidence113(preferably 6° or more) in comparison with the prior art.

The prior art (such as the shoe shown inFIG. 28Aand the '351 patent) includes a heel suspension element that is parallel to the ground. The heel suspension element of the present invention is inclined to properly initiate ground contact during a running or walking stride. The angle of heel inclination is preferably 6° as shown, although other angles may be desirable as well.

A forward suspension element114according to the shoe shown inFIG. 28Bincludes a length of 60-100 mm or more, preferably 95 mm, by a height of 7-20 mm or more, preferably 16-18 mm. When engaging the forward suspension element, the height includes a compressible travel of 5-10 mm or more, preferably 8 mm of travel.

A rear suspension element116according to this shoe includes a length of 60-95 mm or more, preferably 90 mm, by a height of 12-30 mm or more, preferably 25 mm. When engaging the rear suspension element, the height includes a compressible travel of 8-15 mm or more, preferably 13 mm of travel.

FIG. 29shows an embodiment of the present invention where the shoe100includes replacement suspension elements. The shoe may include a replaceable rear suspension element116by including a two-piece outsole104c. The outsole104cincludes a first piece188and a second piece190. The second piece190of the outsole occurs below the rear suspension element116. If/when the rear suspension element116needs to be replaced, the second piece190of the outsole104ccan be removed from the shoe, where the suspension element can then be removed, and replaced with a new suspension element.

To separate and replace a suspension element and/or a portion of the outsole, the outsole may include a fastening material such as a3M dual lock or various hook and loop closures. Other types of fasteners could be used as well such as electrically or chemically releasable adhesives.

Replacement of one or more suspension elements of a shoe according to the present invention may be desired for a variety of reasons. A wearer may desire to change a suspension element to adjust the loading rate of the stock or default suspension element. For example, a heavier wearer (with a weight of 200 lb or greater), may desire to change a “standard rate” suspension element with a “heavy duty” suspension element. This would allow the wearer an ability to tune the shoe for their weight or carrying choice (such as if a wearer was carrying a backpack or other heavy item).

Further suspension element modifications may include different versions tuned to minimize pronation or supination, or may include versions tuned to have greater overall stability compared with standard weight and/or stability suspension. Worn suspension elements or outsole pieces can be replaced with new ones, and outsole pieces can be traded for outsole pieces suited to different terrain (such as a road tread outsole versus a trail tread or winter outsole).

The shoe of the present invention facilitates and optimizes for an entire chain of events to happen during a walk or run stride—from a higher amount of energy storage during heel entry compared to the prior art, to properly timed transfer of that energy during a mid-foot transition, rolling from mid foot to toe-off at completion of the stride.

Additional factors that may be incorporated into the subject shoe include precision-measured last locating of forefoot metatarsals and heel calcaneus, a hinge position relative to metatarsals and a suspension element, timing of heel entry, midfoot, hinge, and forefoot to toe-off relative to energy transfer, a rearward set of heel angles of inclination, as well as modifying forefoot length, width, height, and other mechanics.

The invention illustratively disclosed herein suitably may be practiced in the absence of any element, part, step, component, or ingredient which is not specifically disclosed herein. While in the foregoing detailed description this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purposes of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.