Cushioning shoe insole with plural, differentiated surface-tension cushioning

Abstract

A shoe insole structure which includes a singular (or plural) acceleration-rate-sensitive, differentiated-softness, bonded viscoelastic cushioning layer(s), joined to the upper surface of which is a low-surface-friction, moisture-wicking fabric overlayer. The overall insole presents to a foot an effective upwardly facing support surface which has an effective surface tension which is lower than (differentiated from) that of the underside of the foot.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation from regular U.S. patent application Ser. No. 10/003,122, filed Nov. 14,2001 for "Cushioning Shoe Insole", which application, as does this continuation application also, claims priority to U.S. Provisional Application Serial No. 60/281,604, filed Apr. 4, 2001 for "Cushioning Shoe Insole". Both of these predecessor and serially copending patent applications are hereby incorporated into this application by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

[0002] This invention relates to a new and advantageous shoe insole, and in particular to an insole which is usable in a medically-related environment as, for example, where shoewear is prescribed or recommended for various medical conditions requiring special uniform and highly topographically conformal cushioning to minimize singular high-pressure points applied to the underside of the foot. Especially, the invention proposes an insole structure that provides (a) superior shock-absorbing qualities, (b) reliable, intimate thermo-conformation (spatial conformation) to the topography of the underside of the foot, (c) efficient moisture wicking and related cooling, and (d) avoidance of uncomfortable, "hard landing" "bottoming out" of the foot within a shoe during walking.

[0003] According to a preferred embodiment of the invention, these important performance behaviors are achieved in an insole structure which preferably is layered in nature, and which includes a cushioning layer structure that carries a bonded overlayer of a low-surface-friction, moisture-wicking fabric material, which material, collectively with the cushioning layer structure, presents to the underside of the foot an effective support surface which exhibits an effective surface tension which is less that the surface tension of the underside of the foot. Such a differentiated surface-tension condition has the important effect of promoting close, topographic, cushioning conformation to the underside of the foot, with the important result of offering a high level of cushioning (softness) comfort. Additionally, where, as is especially proposed by the present invention, the cushioning layer structure therein is formed of an acceleration-rate-sensitive material which is slow to restore itself from a deformed condition, under-foot topographic conformation is significantly enhanced.

[0004] There are a number of different ways in which an appropriate and successful cushioning layer can be constructed and implemented. One such successful way involves a single cushioning layer formed of a uniformly characterized acceleration-rate-sensitive material with one softness behavior nature appropriately surface-covered at the surface intend for foot engagement with a low-surface-tension moisture-wicking fabric.

[0005] Another way involves the use of plural, stacked cushioning layers of such acceleration rate-sensitive materials, each having a different softness behavior, and stacked in a softness-progression manner whereby, as between two vertically adjacent layers, the softer one of the two is the upper layer. Here, too, an overlayer of moisture-wicking fabric is employed.

[0006] Still another approach involves employing a single such cushioning layer which is prepared with an internally varying softness, with the softer regions disposed in the layer above the firmer regions. A moisture-wicking ovelayer is also employed in this version of an insole constructed in accordance with the invention.

[0007] In all embodiments and versions of the invention, the effective surface tension of the uppermost surface region of the insole is preferably less than that of the underside of the usual human foot.

[0008] The various features and advantages that are offered by the insole construction proposed by this invention will become more fully apparent as the description which now follows is read in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a simplified top plan view illustrating an isolated, left-foot, cushioning shoe insole which is constructed in accordance with one embodiment of the present invention.

[0010] FIG. 2 is an enlarged, fragmentary side elevation taken generally along the line 2-2 in FIG. 1.

[0011] FIG. 3 is a view somewhat like that presented in FIG. 2, generally illustrating how the insole of FIGS. 1 and 2 provides anti-spring-like, differentiated-softness, cushioning and shock absorbing in accordance with the present invention.

[0012] FIG. 4 is a view much like FIG. 2, except that FIG. 4 shows a modified form of the invention in which the cushioning layer structure includes plural layers, and specifically two layers.

[0013] FIG. 5 is an enlarged, fragmentary cross-section taken generally along the line 5-5 in FIG. 4.

[0014] FIG. 6 is a view which is very similar to that presented in FIG. 5, except that here what is shown is a modified form of the invention in which the shoe insole of this invention possesses a unidirectional, lateral taper defining a high lateral side and a low lateral side.

[0015] It should be understood that components illustrated in the insole of this invention in FIGS. 1-6 inclusive are not necessarily represented therein to scale.

DETAILED DESCRIPTION OF THE INVENTION

[0016] Turning now to the drawing figures, one of the embodiments of the proposed insole structure of this invention is indicated generally at 10. For the purpose of convenience herein, insole 10 is pictured and described in a form wherein it is employable as a free insert for an already constructed shoe. It should be understood, however, that the insole of this invention could easily be incorporated as a part of initial shoe construction.

[0017] Insole 10 includes a heat-flowable, anti-spring-back, acceleration-rate-sensitive cushioning layer structure 12 formed preferably of a material such as the microcdellular, viscoelastic, urethane material known as PORON.RTM. 400 Performance Urethane, Series 90, Formulation #94, manufactured by Rogers Corporation in Woodstock, Ct.

[0018] Layer structure 12, formed as just described, has a shock-cushioning behavior whereby (a) it deforms in an acceleration-rate-sensitive manner (the greater the acceleration, the slower the responsive deflection), and (b) returns slowly from such a deformation toward an undeformed condition without exhibiting any appreciable spring-like mannerisms. By the way of contrast, an undesirable spring-action response to a deflection occurs where a material effectively reacts to, and tends to return from, a force impact deflection condition with a felt return force, and in a time-frame, that generally match those of the event which has produced the subject deflection. A non-spring-like response, which is characteristic of layer structure 12, takes the form of a return (from a shock-force/impact deflection) that is retarded over time, and characterized by a lowered, overall-felt, return-force behavior. In a sense, a material behaving in a non-spring-like manner tends to "creep" back toward an undeformed condition. This is how layer structure 12 behaves in insole 10.

[0019] Another important advantage which is offered by layer structure 12, formed with materials like those mentioned above, is that it tends to flow (at a creep) with heat and compression, and thus tends to deform gradually to create an upwardly facing, topographically-conforming, foot-support surface which tends to complement and "follow" the configuration of the underside of a supported foot.

[0020] Suitably surface-bonded (as by an appropriate hot-melt adhesive) to the upper surface of layer 12 is a thin, fabric, moisture-wicking, low-surface-friction and abrasion-wear layer structure, or layer, 14. Preferably, layer 14 is formed of a woven-fibre fabric material, such as that material known as HEATERSTONE.RTM., made by Lee Fashion Fabrics, in Gloversville, N.Y. Fabric layer 14 herein has a thickness preferably of about {fraction (1/64)}-inches, and includes elongate, stretch-resistant fibres (see 14a in the figures) that function as tension-active, load-distributing components in the fabric.

[0021] Layer 14 plays several important roles (i.e., cooperative with layer structure 12) in insole 10. One of these involves furnishing a wear surface to protect the longevity of the underlying cushioning layer, and to do so without appreciably diminishing the cushioning and shock-absorbing capabilities of that layer. Another involves furnishing a surface which has a low coefficient of sliding friction, so as to minimize friction heat which develops around the foot of a user during normal shoe use. A third important function for this layer is that it wicks moisture which typically develops in a shoe, and caries this moisture efficiently to the side edges (perimeter) of the insole, where that moisture can quickly evaporate, and in so doing, provide cooling within a shoe. A fourth significant function of layer 14 is that its fibres act as elongate load-distributing elements that aid in spreading localized load events to a broader area within insole 10.

[0022] Layers 12, 14 collectively present to the underside of a foot a surface tension characteristic which is less than that of the undersurface of a foot, whether or not the foot is covered by a sock.

[0023] As was pointed out above, the materials which make up cushioning layer structure 12 respond to shock-force/impact loading in such a fashion that this structure has a tendency to return from a deformation (produced by such loading) in a retarded, slow and low-return-force (non-springy) fashion. This "low return-force" behavior is evidenced by the material returning toward an undeformed (unshockdeformed) condition without displaying anywhere near the same level of local return force or pressure which characterizes the initial loading per se.

[0024] FIG. 3 is presented to highlight this important performance of layer structure 12 in insole 10. In solid lines in this figure, structures 12, 14 are shown representationally shock-deflected to produce the combined deformation generally indicated as a depression at D. Dash-double-dot lines show the undeformed "prior" dispositions of the local upper surfaces of these two layer structures.

[0025] Short, solid downwardly-pointing arrow Ti, and long, shaded, downwardly-pointing arrow Fi represent related time-span and applied-force characteristics respectively, of the shock event which has produced deformation D. Long, solid, upwardly-pointing arrow T2, and short, shaded, upwardly-pointing arrow F2, represent the related time-span and return-force characteristics, respectively, of how layer structure 12, in cooperation with layer structure 14, will try to return from the shock-deformed state. As can be seen, T2 is greater in length than is T1, and F1 is greater in length than is F2. These comparative and differentiated "lengths" represent the differentiated time-span and force-level behavior characteristics which characterize the kind of non-spring-factor cushioning response that produces, respectively, the remarkable shoe-cushioning performance offered by the present invention. Fibres 14a, as indicated by reverse arrows in FIG. 3, cooperatively act to distribute and spread load laterally in the insole.

[0026] The several outwardly pointing arrows which radiate from the letter M in FIG. 1 represent how moisture is wicked by layer 14 to the lateral (perimetral) edges of insole 10--the perimeter of the insole. At the perimeter of the insole such wicked moisture readily evaporates, and introduces effective and noticeable cooling in a shoe equipped with the insole.

[0027] Turning attention now to FIG. 4, here there is shown at 20 a modified form of insole which is made in accordance with the present invention. Insole 20 includes a heat-flowable, anti-spring-back, shock (acceleration)-rate-sensitive cushioning underlayer structure (or layer structure) 22, including upper and lower, suitably bonded-together, material layers 22a, 22b, respectively. Each of layers 22a, 22b is formed preferably of a material like that employed for previously described layer structure 12. Upper layer 22a is softer than layer 22b, and preferably is also thicker than layer 22b.

[0028] In insole 20, layer 22a is specifically formed of PORON.RTM. product number SRS-15188-47-54U-RR, and layer 22b of PORON.RTM. product number SRVF-15118-42-54U-RR. Also, and while different relative dimensions can be employed for these two layers, in the embodiment pictured in FIG. 4, layers 22a, 22b have uniform, though different, distributed thicknesses (see also FIG. 5). The thickness of layer 22a, the upper, softer layer, is about 4-mm, and that of lower, firmer layer 22b is about 3-mm. Thus the overall cushioning layer structure 22 herein can be thought of as having, from top surface to bottom surface, a spatially varied softness characteristic which progresses from softer toward firmer downwardly through this layer structure. It will become apparent to those skilled in the art that different useful structural approaches can be employed to create such a varied softness/firmness layer structure.

[0029] Mentioning some of these useful ways in which variations in this cushioning layer structure can be made, layer 22a could be the same thickness as, or thinner than, layer 22b. The absolute, and relative, softnesses of these layers could be varied. Further, layer structure 22 could include more than two viscoelastic layers, or perhaps it could be infinitely graded.

[0030] Bonding between layers 22a, 22b, preferably created by any suitable contact adhesive, produces a certain level of interfacial telegraphy of the individual properties of each layer to the other, and this bonding contributes to the overall performance of the insole.

[0031] Suitably joined to the upper surface of layer structure 22 is a fabric, moisture-wicking layer 24 which is like previously described layer 14. Layer 24 has strands 24a which are like strands 14a.

[0032] Turning attention now to FIGS. 5 and 6, FIG. 5 helps to illustrate the uniform thicknesses of layers 22a, 22b, and 24. FIG. 5 pictures a modified construction for insole 10 wherein the thickness of layers 22a, 22b are laterally tapered. Such tapering can be beneficial in certain instances, and can be made to "slant" in different degrees and directions, if desired.

[0033] Not specifically shown in a drawing herein is another modification of the invention wherein a single cushioning layer, like previously discussed layer 12, is formed with a varying softness characteristic which graduates from softer toward firmer progressing downwardly through the layer

[0034] The insole thus proposed by the present invention offers some very special advantages in relation to conventional insoles. Its construction is quite simple, and it lends itself readily to initial incorporation, and even retrofitting, in many otherwise conventional shoe designs.

[0035] Heating of layer structures 12, 22 during normal use causes the upper surfaces of these layers to form-fit the underside of a user's foot. This is a very important feature of the invention where insoles 10, 20 are employed in a medical situation. The described behavior, strongly contributed to by the fact that the effective surface tension of the upper engagement surface of the insole is less than that of the underside of the usual foot, causes these insoles to form-fit very closely to the underside of the foot, and this performance minimizes high-pressure points of contact with the foot. Accordingly, the insole of this invention promotes good blood circulation.

[0036] Wicking of moisture by layers 14, 24 promotes cooling, and this is important in various medical situations, such as in a diabetes situation.

[0037] Acceleration-rate-sensitivity in layer structures 12, 22 leads to significant anti-springback behavior, and contributes to a remarkable ability of the insole of the invention to cushion shock loads. Also fabric layers 14, 24 act as low-friction, abrasion-resistant upper surfaces in the insoles, protecting layer structures 12, 22 from undue early wear, and minimizing friction-induced heat build-up as the foot naturally moves around in a shoe.

[0038] Accordingly, while preferred embodiments and certain modifications have been illustrated and/or described herein, other variations and modifications may be made within the scope of the invention.

Claims

We claim:

1. A cushioning insole structure for a shoe, which structure presents to a foot an effective support surface having a surface tension which is less than that of the underside of the foot, said insole structure comprising a cushioning layer structure having upward and lower surfaces, and formed of a material which, following deformation, tends to return naturally to an undeformed condition at a rate which is slower than the rate at which it was deformed, and a low-surface-friction, foot-engaging, moisture-wicking layer joined to the upper surface of said cushioning layer structure, said cushioning layer structure and said moisture-wicking layer collectively presenting to the underside of a foot a support surface which exhibits effectively a lower surface-tension characteristic then that of the foot underside.

2. The insole structure of claim 1, wherein said cushioning layer structure is formed from a non-springy, acceleration-rate-sensitive, cushioning and shock-absorbing material.

3. The insole structure of claim 2, wherein said acceleration-rate-sensiti- ve material is a viscoelastic material.

4. The insole structure of claim 1, wherein said cushioning layer structure is characterized by a structural deformation cushioning nature which varies from softer toward firmer progressing downwardly through the layer structure from its said upper surface toward its said lower surface.

5. The insole structure of claim 4, wherein said cushioning layer structure is formed by at least a pair of differentiated-softness, structural cushioning materials disposed one (upper) above the other (lower), and bonded to each other, with the upper cushioning material being softer than the lower cushioning material.

6. The insole structure of claim 5, wherein each of said materials within said cushioning layer structure is formed from a non-springy, acceleration-rate-sensitive, cushioning and shock-absorbing material.

7. The insole structure of claim 6, wherein said shock-absorbing material is a viscoelastic material.