FOOTWEAR SOLE STRUCTURE

Abstract

A dynamic footwear midsole has an upper layer and a lower layer that are connected by a group of heel slats and a group of forepart slats, each slat being connected at hinge regions to the upper and lower layers. The slats in each group are arranged in generally paralleling planes with the heel slats and forepart slats being arranged to cause one group to collapse as the other group expands. An arch support is provided at the midportion of the upper layer is constructed to enable the upper layer to rock about the arch support.

Description

FIELD

The present invention relates to sole structures for footwear and, particularly to footwear having an improved midsole structure.

BACKGROUND

Many types of footwear typically are formed on a last, a foot-shaped form. In a common construction an insole is temporarily attached to the bottom of the last and an upper is draped and stretched over and about the last and the margins of the upper are attached to the peripheral margins of the insole. An outsole then is attached to the shoe bottom. In many types of footwear, for example only, in athletic shoes, a midsole may be provided between the insole and outsole. The midsole may function to provide stability and cushioning for the user's foot, to enhance comfort, reduce risk of injury or to serve other functions. Midsoles commonly are formed from resilient polymeric materials and may have varying degrees of compressibility, resilience and other characteristics depending on the combinations of materials used, midsole shape and geometry.

It is among the general object of the present invention to provide an improved midsole construction and improved footwear embodying an improved midsole structure.

SUMMARY

A midsole is provided to have an upper layer and a lower layer spaced below the upper layer, each layer having a peripheral contour approximating a human footprint. The upper layer, which is relatively stiff longitudinally, has an arch support formed in its mid-region. The upper and lower layers are connected by a plurality of slats that extend transversely of the midsole. The slats are arranged in two groups, including a forepart group located between the arch support and the toe region and a heelward group located between the arch and heel end of the midsole. The slats in the forepart group are inclined in an upward and toeward attitude, and are in generally paralleling planes and the slats in the heelward group are inclined in an upward and heelward attitude, and also are in a generally paralleling planes. The junctions of the slats with the upper and lower layers are formed to define hinge regions that enable the upper layer to move relative to the lower layer as the user walks or runs. The region beneath the arch support is reinforced to be more resistant to heightwise compression so that it can function in a fulcrum-like fashion to support the foot as it pivots to transfer weight from heel to toe in a walking or running gait.

THE DRAWINGS

The objects and advantages of the invention will be apparent more fully from the following description, with reference to the accompanying drawings in which:

FIG. 1 is a somewhat diagrammatic side view of a shoe having a midsole in accordance with an embodiment of the invention;

FIG. 2 is a plan view of the midsole as seen from 2-2 of FIG. 3;

FIG. 3 is a side view of the midsole;

FIGS. 4A and 4B are views of heel slats as seen along the lines 4A-4A and 4B-4B of FIG. 2;

FIGS. 4C and 4D are views of forepart slats as seen along the lines 4C-4C and 4D-4D of FIG. 2;

FIG. 5 is a somewhat diagrammatic, longitudinal section of the midsole when a runner's weight is on the heel, as shown in FIG. 5A:

FIG. 5A illustrates a runner with weight on the heel of the midsole;

FIG. 6 is a somewhat diagrammatic, longitudinal section of the midsole when a runner's weight is on the arch as shown in FIG. 6A:

FIG. 6A illustrates a runner with weight on the arch of the midsole;

FIG. 7 is a somewhat diagrammatic, longitudinal section of the midsole when a runner's weight is on the forepart, as shown in FIG. 7A; and

FIG. 7A illustrates a runner with weight on the forepart of the midsole;

FIGS. 8A and 8B are illustrations similar to FIGS. 4A and 4B of heel slats in a modified embodiment; and

FIGS. 8C and 8D are illustrations similar to FIGS. 4A and 4B of forepart of the invention, slats in a modified embodiment; and

FIG. 9 is an diagrammatic illustration of a user's foot with the user's weight on the forepart of the midsole in the region of a modified forepart slat.

ILLUSTRATIVE EMBODIMENTS

As shown in FIG. 1, an illustrative article of footwear, such as an athletic shoe, has an upper 10, an insole (not shown), a midsole 12 and an outsole 14. The midsole 12, also shown in FIGS. 2-5, has an upper layer 16 and a spaced lower layer 18, both of which have a peripheral edge 20 in a general outline of a human footprint.

The midsole may be formed from any of a variety of commercially available polymers, as by injection molding or by using additive manufacturing techniques (e.g., 3-D printing) and may be considered to have a heel portion 22, a forepart portion 24 and a midportion 26 between the heel and forepart portions 22, 24. The upper and lower layers 16, 18 are connected together by a plurality of inclined slats, including a group of forepart slats 28 and a group of heel slats 30. The upper layer 16 is provided, in its midportion 26, with an arch support 32. As described in more detail below, the arrangements of heel slats and forepart slats allow the heel and forepart regions of the midsole to be resiliently compressed, alternately, while also permitting some relative longitudinal movement of the layers in response to the shifting weight of the user when walking or running. In the embodiment shown in FIGS. 2 and 3 the slats 28, 30 may extend transversely the full width of the midsole from the inner (medial) side M to the outer (lateral) side L or may be modified as described below. As shown in FIG. 2, the slats 28, 30 may be oriented at an angle A to the midsole centerline 31 (extending between the heel and toe extremities of the midsole), preferably between about ten to about twenty degrees with the medial ends of the slats being disposed toeward of their lateral ends as I have found this to provide a more comfortable configuration. The principles of the invention, however, are not limited to any specific angle, and in some cases the slats could extend closer to perpendicular to the centerline.

The slats within each group are disposed in generally paralleling planes and are attached to and extend between the upper and lower layers 16, 18 at upper and lower hinge regions 34, 36, respectively. The hinge regions and materials from which the midsole is formed should provide for a cumulative, desired degree of resilience to provide cushioning as weight is applied as well as contributing to forward propulsion as the weight is transferred from heel to toe. It will be appreciated that the arrangement of any pair of adjacent slats and the segments (16a, 16b, . . . 16n and 18a, 18b, . . . 18n) of the upper and lower layers that connect to that slat pair define and function as a four-bar linkage that encloses a variable, prism-shaped cell or void 38.

Although the slats in each group are generally parallel to each other, the slats 30 of the heel group are not parallel to the slats 28 of the forepart group. Thus, as shown, the forepart slats 28 are inclined in an upward and toeward orientation; the heel slats 30 are inclined in an upward and heelward orientation. This orientation of the slats 28, 30, coupled with the compressive resistance of the arch support region of the midsole, provides a dynamic action in which, the upper layer 16 can rotate about the arch support 32, which functions as a fulcrum, as the user's weight shifts progressively from heel to toe. Thus, as shown in FIGS. 5 and 5A, as a runner's heel engages the ground, the heel region of the midsole is compressed against the resilience of the heel region, causing the heel slats 30 to rotate within the midsole (counterclockwise as seen in FIG. 5). That, in turn, causes the forepart portion 24 of the relatively stiff upper layer 16 to pivot relative to the lower layer and about the arch support, causing the forepart of the upper layer to move away from the lower layer 18 with the forepart slats 28 rotating (also counterclockwise) as the spacing between the forepart portions of the upper and lower layers increases. As the runner's weight unloads from the heel portion 22 and shifts to the midportion 26 (FIGS. 6 and 6A) and then to the forepart portion 28 (FIGS. 7 and 7A) of the midsole, the heel slats 30 and forepart slats 28 rotate within the midsole (clockwise), the stored restorative resilient force of the heel portion may aid the runner as weight is transferred forwardly to cause resilient compression of the forepart region. As the runner's stride continues and the forepart is unloaded, the stored restorative resilient force of the forepart portion resilience may aid in the runner's forward motion.

The arch support is contoured to support the arch region of the user's foot and, preferably, may be formed integrally as a unit with the upper layer. The upper layer should be relatively stiff along the length of the midsole, sufficiently so that the slats and their connecting segments of the upper and lower layers function as a four-bar linkages as described above, without significant distortion of the slats and connective segments (16a, 16b . . . 16n and 18a, 18b, . . . 18n) of the layers. The stiffness can be achieved by various combinations of material selection, dimensional adjustments, and embedded stiffeners, as will be familiar to those skilled in the art. The arch support should be the least compressible portion of the midsole to facilitate its function as a fulcrum. To that end the arch support may extend from the junction region of the most toeward slat 30h of the heel group to the most heelward forepart slat 28f, both of which may be thicker and have more robust hinge regions to provide support for the arch. Additional supports may be included as supplemental support below the arch as, for example, by one or more heightwise and longitudinally extending support braces extending between the underside of the arch and the lower layer, the forward and rearward ends of the brace(s) being attached to the support slats 30h and 28f.

FIGS. 8, 8A, 8B, 8C and 8D illustrate modified embodiments of slats in which the one or both of the end regions of the slats may be modified by eliminating some end portions of some of the slats. In this modifications, selected ends of selected slats may have cut-away portions CA that have the effect of varying the degree of medial-lateral support provided by the midsole. For example, FIG. 8D illustrates an example of a slat configuration with a greater cut-away on the medial end M of the slat than on the lateral end L so that the user's foot will tend to cant as shown in FIG. 9. It will be appreciated that the configurations of the slats, as well as other parts of the midsole may be modified to provide a midsole having support characteristics tailored and customized to a particular user, for example, to provide enhanced performance, greater comfort, an appropriate corrective function or other characteristic. Commercially available gait analysis systems may be employed to analyze a user's gait so as to inform making of such customized midsoles.

Midsoles in accordance with the invention are not limited to use in athletic footwear but may be used with other types of footwear such as conventional shoes, sandals, hiking and other boots, flip-flops, among others. It should be understood that the foregoing description of the invention is intended merely to be illustrative thereof and that other embodiments and modifications may be apparent to those skilled in the art without departing from the principles of the invention.

Claims

1. A footwear midsole comprising:

an upper layer;

a lower layer;

each of the layers having a heel portion, a midportion and a forepart portion; an arch support at the midportion of the upper layer; a plurality of generally planar heel slats extending transversely between and hingedly connected to the heel portions of the upper and lower layers; a plurality of generally planar forepart slats extending transversely between and hingedly connected to the forepart portions of the upper and lower layers; the arch support being of sufficient strength to present greater resistance to heightwise compression than the heel and forepart regions;

2. The midsole as defined in claim 1 further comprising:

the heel slats being inclined in an upward and heelward direction; and

the forepart slats being inclined in an upward and toeward direction.

3. The midsole as defined in claim 1 further comprising:

the upper and lower layers and the slats being formed as a unitary, one-piece structure.

4. The midsole as defined in claim 2 further comprising:

the upper and lower layers and the slats being formed as a unitary, one-piece structure.

5. The midsole as defined in claim 2 further comprising:

the arch support extending between the most toeward slat of the heelward group and the most heelward slat of the forepart group

6. The midsole as defined in claim 5 further comprising:

the most toeward slat of the heel group and the most heelward slat of the forepart group being attached, respectively, to the upper layer at the toeward and heelward regions of the arch support.

7. The midsole as defined in claim 6 further comprising:

the most toeward slat of the heel group and the most heelward slat of the forepart group being thicker and having less flexible hinge regions than the other slats.

8. The midsole as defined in claim 6 wherein the support structure for the arch support further comprises:

at least one longitudinally and heightwise extending support brace connected between the upper layer and the lower layer and between the most heelward slat of the forepart group and the most toeward slat of the heel group.

9. The midsole as defined in claim 1 and having a centerline extending between the heel and toe extremities and further comprising:

the slats extending at a non-perpendicular angle to the centerline with the medial ends of the slats being toeward of the their lateral ends.

10. The midsole as defined in claim 9 wherein the angle is between about ten and twenty degrees.

11. The midsole as defined in claim 2 wherein the slats in each group are arranged in generally paralleling planes.

12. The midsole as defined in claim 1 wherein the upper and lower layers and longitudinally spaced slats define a plurality of hollow prism-shaped cells, each being defined by a pair of adjacent slats and a segment of each of the upper and lower layers.

13. The midsole as defined in claim 2 wherein the upper layer is sufficiently stiff to enable the upper layer to rock about the region of the arch support in heelward and toeward directions.

14. The midsole as defined in claim 12 wherein the upper layer is sufficiently stiff to prevent distortion of the segments of the upper layer in response to rocking of the upper layer about the arch region.

15. An article of footwear comprising:

an upper;

a midsole as defined in claim 1 attached to the upper; and

an outsole attached to the lower layer of the midsole.